NIST Special Publication 840

Proceedings of the 4th

U.S.-Japan Workshop on

Earthquake Disaster Prevention

for Lifeline Systems

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NIST Special Publication 840

Proceedings of the 4th

U.S.-Japan Workshop on

Earthquake Disaster Prevention

for Lifeline Systems

Held at the Biltmore Hotel

Los Angeles, California

August 19-21, 1991

Edited by

Ronald T. Equchi

Dames & Moore

United States

Publication Coordinator

Robert D. Dikkers

Building and Fire Research Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899

Sponsored by

National Science Foundation

United States

Public Works Research Institute

Japan

U.S. Department of Commerce

Barbara Hackman Franklin, Secretary

Technology Administration

Robert M. White, Under Secretary for Technology

National Institute of Standards and Technology

John W. Lyons, Director

August 1992
National Institute of Standards and Technology Special Publication 840

Natl. Inst. Stand. Technol. Spec. Publ. 840, 468 pages (Aug. 1992)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1992

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402-9325
FOREWORD

ACKNOWLEDGMENTS

TABLE OF CONTENTS

PAGE

vii

X

I. SOIL EFFECTS

Performance of Water Supply Pipelines in Liquified Soil 3

K.A. Porter, C.R. Scawthorn, D.G. Honegger,

T.D. O'Rourke, F. Blackburn

A Proposal of Practical Earthquake Response Analysis 1

Method of Cylindrical Tunnels in Soft Ground

Y. Shiba, S. Okamoto

Visual information System for Seismic Ground Hazard 35

Zoning

K. Tokida, H. Matsumoto, Y. Sasaki

II. SEISMIC DESIGN AND ANALYSIS: TRANSPORTATION

Seismic Risk Identification and Prioritization in the 55

CALTRANS Seismic Retrofit Program

B. Maroney, J. Gates

An Old Bridge Gets a Seismic Facelift 77

G.M. Snyder, C.E. Lindvall, R. P. Lyons

Seismic Inspection and Seismic Strengthening of Highway 91

Bridges in Japan

K. Kawashima, S. Unjoh, H. lida

Recent Advances in Seismic Design and Retrofit of 1 25

California Bridges

J.E. Roberts

IIL SEISMIC DESIGN & ANALYSIS: PIPEUNES & TUNNELS, PART ONE

Repair and Rehabilitation of Buried Water and 1 39

Sewer Lifelines

LR.L Wang, H. Kennedy

iii
Investigations on External Force Evaluation in the 1 55

Seismic Deformation Method

N. Takahashi, M. Takeuchi, K. Irokawa

Estimation of System Reliability for Lifeline Standards 1 69

and Example Using the City of Everett, Washington Lifelines

D. Ballantyne

Dynamic Response of Twin Circular Tunnels during 1 81

Earthquakes

T. Okumura, N. Takewaki, K. Shimizu, K. Fukutake

Development of Seismic Design and Construction Standards 1 93

for Lifelines

R. Dikkers

IV. SEISMIC DESIGN & ANALYSIS: PIPELINES & TUNNELS. PART TWO

Data Base of Pipeline Failures, Loma Prieta Earthquake, 201

October 17. 1989

L. Lund

Behavior of Flat Underground Structures during Earthquakes 207

and Seismic Loads Acting on Them

S. Mori, T. Ikeda, K. Matsushima, H. Tachibana

Seismic Response of Super-Deep Vertical Shaft with 21

9

Circular Cross-Section

N. Ohbo, K. Hayashi, K. Ueno

Seismic Design Method of Shield Tunnels with Axial 229

Prestressing by Means of Rubber and PC Bar

K. Matsubara, K. Urano

Seismic Isolation for Underground Structures 245

K. Ono, S. Shimamura, H. Kasai

V. SEISMIC RISK ANALYSIS

Performance of AWSS and PWSS of San Francisco During 263

and After Loma Prieta Earthquake

M.M. Khater, C.R. Scawthorn, T.D. O'Rourke, F. Blackburn

iv
Seismic Reliability Analyses of Large Scale Lifeline 277

Networks Taking into Account the Failure Probability

of the Components

T. Sato, K. Toki

Earthquake Damage Analysis on Telecommunication Conduits 293

K. Yagi, S. Mataki, N. Suzuki

Regional Risk Assessment of Environmental Contamination 307

from Oil Pipelines

S.D. Pelmulder, R.T. Eguchi

Damage Assessment of Lifeline Systems in Japan 321

M. Hamada

VL POST-EARTHQUAKE RESPONSE/DAMAGE DETECTION

Data Acquisition and Emergency Response System for 337

City Gas Pipeline Operation During a Major Earthquake '

Y. Yoshikawa

Damage Inspection Systems Immediately after an Earthquake 349

K. Kawashima, H. Sugita, K. Kanoh

Estimation of Degree of Anxiety Felt by People in 365

Underground Urban Spaces During Earthquakes

E. Saito, H. Ikemi, H. Nakano, M. Nakamura

Performance of Lifeline and Emergency Response in 381

Watsonville, California to Loma Prieta Earthquake

J. Isenberg

Strategies for Repair and Restoration of Seismically 391

Damaged Gas Pipeline Systems

M. Shinozuka, M. Murata, T. Iwata

VII. SOCIOECONOMIC IMPACTS

Lifeline Earthquake Hazard Zonation in Socio-economic 409

Aspects

E. Kuribayashi

Organizational Features of U.S. Lifeline Systems and 423

their Relevance for Disaster Management

K.J. Tierney

V
A Methodology for Assessing the Risk of Hazardous

Materials Release Following Earthquakes - A Demonstration

Study for the Los Angeles Area

H.A. Seligson, R.T. Eguchi, K.J. Tierney

WORKSHOP RESOLUTION

APPENDICES

Workshop Program

Workshop Participants

Photos

vi
FOREWORD

The future of lifeline earthquake engineering depends, in large part, upon our ability

to develop and communicate new concepts and ideas for design, construction, operation,

and post-event restoration of lifelines. For the past several decades, the governments

of Japan and the United States have shared the belief that the exchange of information

and resources is integral in improving the seismic performance of lifeline systems in both

countries. Both countries have supported opportunities to meet in technical meetings to

discuss the development of technologies to mitigate seismic effects on lifeline systems.

One ongoing activity has been to meet under the auspices of the U.S. -Japan Natural

Resources (UJNR) program.

To date, there have been three previous workshops organized by the Panel on

Wind and Seismic Effects of the UJNR program with specific focus on the seismic

performance of lifelines:

U.S. -Japan Workshop on Lifeline Systems, Washington, D.C, 1984

Second U.S.-Japan Workshop on Seismic Behavior of Buried Pipelines and

Telecommuncation Systems, Tsukuba, Japan. 1984

Third U.S.-Japan Workshop on Earthquake Disaster Prevention for Lifeline

Systems, Tsukuba, Japan, 1989

The following proceedings document the results of the Fourth U.S.-Japan

Workshop on Earthquake Disaster Prevention for Lifeline Systems. This workshop was

jointly sponsored by the National Science Foundation (NSF) of the United States, and by

the Public Works Research Institute (PWRI) of Japan. Additional financial support for this

workshop was provided by the National Institute of Standards and Technology (NIST)

and the Metropolitan Water District of Southern California. The workshop was held at the

Biltmore Hotel in Los Angeles, California, between August 19-21, 1991, and was

organized by Task Committee F, "Disaster Prevention Methods for Lifeline Systems,"

UJNR Panel on Wind and Seismic Effects. Mr. Ronald T. Eguchi of Dames & Moore, Mr.

Robert Dikkers of NIST, Professor Henry Lagorio and Dr. S.C. Liu of NSF, and Drs. Y. Sasaki and K. Kawashima of PWRI led the organization of this workshop.

vii
The theme of this workshop focused on "Future Directions for Research,

Application and Design of Lifeline Systems." Developing this theme required an

examination of past research activities, an assessment of current research efforts, and

recommendations for future directions for seismic vulnerability assessment and design,

and emergency response and planning. It is intended that collectively, these papers will provide the basis for establishing priorities for future joint activities between both

countries.

In this workshop, a broad range of technical topics were discussed. These

included:

Effects of Soils on Lifeline Components;

Seismic Design and Retrofit of Lifeline Facilities;

Dynamic Response and Analysis of Lifeline Facilities;

Repair and Rehabilitation of Lifeline Systems;

System Reliability Methods for Lifeline Systems;

Post-Earthquake Damage Detection Procedures;

Socio-Economic and Environmental Impact of Lifeline System Failures;

Emergency and Disaster Response Management of Lifeline Systems.

In total, thirty papers were presented in the two days of plenary sessions; 16

papers from Japan and 1 4 papers from the U.S.

In addition, the workshop was highlighted by:

Active Question and Answer periods after each session;

A full-day field trip to the Ralph's Grocery Company Automated Warehouse

Distribution Center, the Metropolitan Water District of Southern California's

Joseph Jensen Filtration Plant and several CALTRAN's facilities; and

Resolutions fully supported by the participants of both countries that identify

future research priorities and cooperative activities between the two

countries.

viii
The materials in this proceedings are presented as follows: (1 ) all technical papers

that were presented during the workshop are provided in their order of presentation;

(2) resolutions that were unanimously adopted by the participants during the closing

session of the workshop, and (3) appendices that include the workshop program, list of

participants, and photos to commemorate the workshop.

ix
ACKNOWLEDGMENTS

The organizers of the workshop would like to thank the National Science

Foundation and the Public Works Research Institute for sponsoring the workshop and its

activities. In addition, the organizers would like to acknowledge the Metropolitan Water

District of Southern California for sponsoring dinner activities, and the National Institute

of Standards and Technology for its support in the printing of this document.

At the National Science Foundation, we would like to thank Professor Henry J. Lagorio and Dr. S.C. Liu for their guidance and support in this effort.

We extend our sincere appreciation and thanks to the members of Dames &

Moore who helped to organize the workshop and who assisted in the actual meeting of

the workshop participants. In particular, we would like to acknowledge the efforts of Ms.

Julee Mon of Dames & Moore who worked many extended hours to insure the success

of the workshop. Special thanks are also extended to Ms. Susan D. Pelmulder, Ms. Mary

Jean Koontz, and Ms. Carmela Valeric, all members of Dames & Moore.

Ronald T. Eguchi

Dames & Moore

Kazuhiko Kawashima

Public Works Research Institute

Workshop Organizers

X
I. SOIL EFFECTS

"Performance of Water Supply Pipelines in Liquified Soil"

K.A. Porter, C.R. Scawthorn, D.G. Honegger,

T.D. O'Rourke, F. Blackburn

"A Proposal of Practical Earthquake Response Analysis

Method of Cylindrical Tunnels in Soft Ground"

/. Shiba, S. Okamo to

"Visual Information System for

Seismic Ground Hazard Zoning"

K. Tokida, H. Matsumoto, Y. Sasaki

PERFORMANCE OF WATER SUPPLY PIPELINES IN LIQUEFIED SOIL

K.A. Porter, C. Scawthorn, D.G. Honeggeri, T.D. G'Rourke^, F. Blackburn^

ABSTRACT

Reliable performance of underground water supply pipe in earthquakes is a matter of critical importance, to support immediate firefighting and assure potable water supply. Existing approaches to estimating water pipe

breakage, based primarily on estimated MMI, may underestimate major pipe

damage concentrated in regions of large liquefaction-induced permanent

ground deformations. A recent study {San Francisco Liquefaction Study)

necessitated estimation of pipe breakage in areas of potential large

permanent ground deformations associated with liquefaction and lateral

spreading. Data from the 1906 San Francisco and 1989 Loma Prieta

earthquakes were used to correlate pipe break as a function of permanent

ground deformation. The results tend to agree with previous studies from

the 1971 San Fernando and several Japanese earthquakes. The major

finding is that normalized pipe break rate is nonlinear with permanent

ground displacements. Relatively small displacements cause significant

initial pipe breakage; at larger displacements additional breaks occur, but at a relatively smaller rate.

1 INTRODUCTION

The vulnerability of buried water supply pipe due to earthquake is of critical

significance, both for post-earthquake fire as well as for continued potable water supply.

It has long been recognized that, while earthquakes cause pipe breakage over wide areas, damage is especially concentrated in areas where liquefaction and lateral spreading have

produced large permanent ground deformations (Schussler, 1906). A number of studies

have examined water supply piping in earthquakes, but most have relied on gross regional

performance, producing correlations with seismic intensity measures such as Modified

Mercalli Intensity (MMI), or peak ground acceleration (PGA). While these measures may

be adequate for overall estimates of regional performance, they tend to underestimate

damage concentrated in regions subject to liquefaction and lateral spreading. Other

studies have developed analysis techniques that provide failure criteria for pipe subjected

to simplified models of ground displacements, well specified with regard to location and

dimensions of ground deformation (eg, Eguchi, 1983a; O'Rourke et al, 1985). These

1 Project Engineer, Vice President and Project Manager (respectively),

EQE Engineering, Inc., San Francisco CA 94105

2. Professor of Civil Engineering, Cornell University, Ithaca NY

3. President, PWSS Ltd. Inc., San Francisco CA

3
methods generally cannot yet be used for water system vulnerability assessments, since

currently feasible geotechnical engineering methods only permit estimation of area-wide

trends of ground settlement or lateral spreading. A need therefore exists, where area-wide

quantified trends of ground settlement or lateral spreading is feasible, but vulnerability measures of underground piping subjected to these deformations are lacking.

In an attempt to fill this need, this study addresses the estimation of damage to buried

water pipe subjected to estimated (ie, quantified, although imprecisely) permanent ground

displacements. This work grew out of a recent study ("San Francisco Liquefaction Study,"

Harding Lawson et al 1991) which necessitated the development of relationships for the

estimation of water pipe damage in regions of potential ground failure. Specifically, this

paper describes the development of correlations between gross water pipe break rate and

general magnitude of permanent ground displacement, regardless of pipe orientation.

2 LITERATURE REVIEW

This section briefly reviews key literature on water pipe seismic vulnerability, as a function of seismic intensity, fault offset, ground movement and joint type.

2.1 WATER PIPE DAMAGE CORRELATED WITH GROUND SHAKING INTENSITY

Kubo and Isoyama (1980), as well as Katayama, Kubo, and Sato (1975) provided damage

rates based on gross regional performance of pipe subjected primarily to JMA V (MMI

Vn-Vni) ground shaking. In the 1978 Miyagi-Ken-Oki Earthquake, and in the 1923

Kanto and 1968 Tokachi-oki earthquakes, failure ratios in JMA V ground shaking ranged

between 0.012 and 0.379 failures per 1000 feet of pipe, depending on material. Cast iron

pipe failure ratios ranged between 0.17 and 0.40 breaks per 1000 feet of pipe, not

including "joint loosenings," whose definition Katayama et al could only conjecture.

Eguchi (1983b) summarized pipe break rate versus MMI for several United States

earthquakes, developing a bilinear semilogarithmic curve for cast iron pipe subject to ground shaking effects only (Figure 1). He found that damage rates increase rapidly with

MMI, and then more slowly as MMI exceeds VIII.

2.2 WATER PIPE DAMAGE CORRELATED WITH FAULT OFFSET

Duryea et al (1907) describe damage to cast and riveted iron pipeline crossing fault

offsets in the 1906 earthquake. They indicate that cast and riveted iron pipe fractured

wherever it crossed a fault offset of several feet. Photographs of the damage indicate

that riveted iron pipe fractured at riveted joints, through shear of the rivets.

Eguchi (1981) presents damage to buried cast iron water pipe near faulting during the

1971 San Fernando Earthquake. He correlated damage with fault displacement and

distance from the predominant line of fault rupture (Figure 2). Ground shaking effects

accounted for relatively little breakage.

Eguchi also evaluated the effect of joint type on break rate in the Sylmar fault area. He

found that breaks rates were similar for pipes with caulked joints and pipes with rubber

gasket joints, and that the predominant modes of failure for pipe in these areas were joint

4
failure, pipe ruptures, and splits. Cement-caulked joints had a tendency to shatter while

pipes with rubber gasket couplings tended to pull apart.

2.3 PIPE DAMAGE CORRELATED WITH LIQUEFACTION-INDUCED GROUND

MOVEMENT

Several authors provide data or correlations between pipe breakage and degree of

permanent ground deformation. O'Rourke et al (1989) describe ground movement as well

as pipe breakage in San Francisco's Sullivan Marsh and Mission Creek in the 1906 San

Francisco earthquake. Pipe breakage data is taken from Schussler (1906), who provided a map showing water main breaks identified in the three months following the earthquake

(Figure 3). Using photographs and other records, O'Rourke mapped ground movements in

the Embarcadero and South of Market (e.g.. Figure 4).

In later work, O'Rourke et al (1990) provided ground settlement contours in the Marina

District in the 1989 Loma Prieta earthquake, and overlaid pipe breakage records on the

settlement map (Figure 5). The data from 1906 San Francisco and 1989 Loma Prieta

earthquakes are used in the present paper to develop break rate relations for water pipe

in liquefied soil. Hamada (1989) described Noshiro City gas pipe damage that occurred in liquefied soils in

the 1983 Nihonkai-Chubu earthquake. Damage to cast iron gas pipe reached

approximately 21 breaks per 1000 feet of pipe, where displacements were on the order of

2 feet.

Eguchi (1983b) provides a constant figure, 1.8 break per 1000 feet for cast iron pipe

subjected to landslide, and 1.0 breaks per 1000 feet for cast iron pipe subjected to liquefaction and lurching, regardless of displacement.

2.4 AFFECT OF JOINT TYPE ON PIPE DAMAGEABILITY

Shaoping et al (1983) studied the contribution of joint damage to overall pipe damage.

They point out that joints are the weakest points in segmented pipe, and that lead filled

joints were superior to cement filled joints, since the latter are brittle and cannot sustain even small deformation. In the Tangshan Earthquake, where break rates in the

mezoseismal area reached 10.0 per km (3.0 per 1000 ft), the rate of damaged joints was

79.6%. In Haicheng, approximately 60% of breaks were associated with joints.

3 PIPE TYPES AND BREAK DATA

3.1 SAN FRANCISCO WATER SYSTEMS AND PIPE TYPES

San Francisco possesses three water supply systems: two specifically for firefighting use and one for both fire fighting use and municipal use (potable water). The two

firefighting systems are the truck-borne Portable Water Supply System (PWSS), and the

underground Auxiliary Water Supply System (AWSS). Both are owned and operated by

the San Francisco Fire Department (SFFD). The Municipal Water Supply System (MWSS)

is owned and operated by the San Francisco Water Department (SFWD).

5
The two systems incorporate a variety of pipe materials and construction. The pipe can

be roughly classified into 7 types: bell and spigot cast iron, double-spigot cast iron with

heavy walls, ductile iron with rigid joints, ductile iron with flexible joints, riveted steel,

gas welded steel, and arc welded steel.

Bell and Spigot Cast Iron Pipe

The majority of MWSS water mains are of this type. Until the 1930's, pipe was vertical

pit cast iron, 12 feet long, typically exhibiting brittle mechanical properties with tensile

strengths on the order of 15 ksi (Ahmed, 1990). Joints were sealed with an oakum gasket

and packed with lead caulk. Restraint was typically provided at dead ends and branch

installations. After 1930, centrif ugally cast iron came into wide use in water systems.

Also brittle, this material nonetheless exhibits strengths on the order of 35 ksi. The

advantage of stronger material may be offset to some degree by the stiffer joint

construction to which SFWD switched at around the same time. Around the 1930s, SFWD

began to seal joints with a rubber gasket and dry mortar caulk.

Virtually all the water mains affected in the Marina District by the October 17, 1989

Loma Prieta earthquake were of the pre-1930 construction, as were all mains 24 inches in

diameter or smaller in the 1906 San Francisco earthquake.

Double Spigot. Heavy Wall Cast Iron Pipe

This is the type of pipe used for the AWSS. Four characteristics tend to make AWSS cast iron pipe stronger and more flexible than MWSS cast iron pipe: double spigot joints, heavy

walls, extra restraint, and fewer lateral connections. Each of these characteristics might

be expected to reduce AWSS pipe vulnerability relative to cast iron water pipe described

above.

Double spigot joints use cast iron or cast steel sleeves, sealed with lead and oakum, as shown in Figure 6. This type of construction allows twice as much joint rotation as does

bell and spigot construction with a similar lead/oakum seal. The Schedule H pipe used in

the AWSS has walls typically 60% thicker than those of the MWSS cast iron pipe. Since

the AWSS operates at higher pressure than MWSS, extra restraint is employed. Rods

connect as many as 10 pipe segments at turns, tee joints, hills and other points of likely

stress, as opposed to the restraint of one joint in MWSS tees. Finally, since AWSS contains no service connections (it is a dedicated firefighting only system), laterals occur only at hydrants and branches. Laterals provide restraint and may act as concentrated load

points on a water main, potentially resulting in additional pipe damage.

Ductile Iron Pipe with Rigid Joints

After about 1960, ductile iron was used for MWSS pipe of 16 inch or smaller diameter,

with geometry and construction similar to the cast iron it replaced, but cast centrif ugally

in 18 foot lengths. SFWD continued to use gasket and grout joints in new ductile iron

pipe construction until 1989.

Ductile Iron Pipe with Flexible Joints

Since 1989, SFWD pipe joints have employed U.S. Pipe's Field Lok Gasket, an elastomeric

gasket fitted with mechanical teeth that provide longitudinal restraint (Figure 7). The

gasket requires no packing, thereby allowing significant rotational flexibility.

6
Riveted and Welded Steel

Pre-1930 MWSS pipe larger than 24 inch diameter is of riveted iron or steel construction.

Longitudinal joints were shop riveted; circumferential joints were riveted in the field.

Gas welding came into use around 1930; during the 1940s, arc welding found widespread

use. After about 1960, pipe larger than 20 inch diameter was of welded steel. Joints were

bell and spigot with fillet welds at the lap joint. Pipe less than 24 or 30 inches in

diameter received a single fillet weld on the outside. Pipe 30 or 36 inches in diameter or

larger were welded inside and outside. Weld leg size was equal to pipe thickness.

3.2 1906 PIPE DAMAGE AND GROUND MOVEMENTS

Records of water main damage within San Francisco were not kept during the few

months following the 1906 earthquake. The only source of data is a map supplied by

Schussler (1906), who recorded 300 main breaks and over 23,000 service breaks by July

1906. Broken mains of all diameters from 2 or 3 inches up are indicated in Schussler's

map. As Schussler noted, it is likely that this record is incomplete; many streets were still covered with debris at the time the map was prepared, and no doubt more pipe damage

was uncovered as the restoration process continued. Pipe breakage data from the 1906

earthquake therefore must be employed with caution.

Where no breaks or occasional breaks appear on the map, no conclusion can be drawn,

since breaks may have remained buried beneath rubble. More confidence may be placed

in the completeness of the record for individual blocks that had numerous breaks. One

may conclude that on these blocks, breaks were found by restoring service pressure over

that block. Restoration of service pressure would have required identification and repair

of most or all the breaks.

3.3 1989 PIPE DAMAGE AND GROUND MOVEMENTS

The 1989 Loma Prieta earthquake resulted in over 160 MWSS pipe breaks, approximately

3/4 of which were located in the Marina District. Breaks within the Marina were

concentrated in the regions of hydraulic fill created circa 1906-1917. Locations of water

main and service breaks are shown in Figure 8, which is based on SFWD records. In the

next section, these will be correlated with liquefaction-induced ground settlements.

Lateral spreading as large as 7 inches over 100 feet is known to have occurred in the

Marina in 1989 (Harding Lawson Associates et al, 1991), but lateral movements have not

been mapped.

4 ANALYSIS

4.1 BELL AND SPIGOT CAST IRON PIPE

In order to develop estimates of pipe breakage resulting from area-wide permanent

ground deformation, break rates in San Francisco water mains was correlated with

amount of ground settlement observed in the Marina in 1989, and lateral spreading

observed in Sullivan Marsh and Mission Creek areas in 1906. Marina data was used

primarily to develop break rate estimates at low permanent ground displacements; the

1906 data included displacements up to 6 feet.

7
Because records of settlement are available in the Marina, and records of lateral

movement are available in the Sullivan Marsh and Mission Creek, our analysis equates

vertical settlement with permanent lateral ground displacement. This was done despite it being generally known that lateral displacements of the same order of magnitude as vertical displacements are known to have occurred in the Marina (good lateral

displacement data however are lacking). As a result, our analysis may underestimate total

displacements in the Marina.

Low Displacement/1989 Marina Data Analysis

To develop a break rate relationship for low displacements, breaks within the area of the

Marina that experienced settlement were aggregated to the nearest street intersection. The

number of breaks at each intersection was then divided by the average length of pipe

associated with an intersection. No differentiation was made for pipe diameter or pipe

orientation relative to ground movement. The resulting break rate and settlement data

per intersection were then used to correlate breaks per 1000 linear feet of pipe with

permanent ground displacement (ie, settlement).

Large Displacement/ 1906 Data Analysis

Ground movements as large as nine feet occurred in several parts of San Francisco in the

1906 earthquake, causing widespread damage to pipe of the same construction as existed

in the Marina in 1989. Five locations were selected and data taken from Schussler's map

and O'Rourke's ground movement records of the 1906 earthquake (O'Rourke et al, 1990).

Data were only drawn from locations where both the damage record and ground

movement record appear to be complete. It should be noted that the assumptions

regarding completeness of the pipe break record (described above) may tend to bias

damage data toward atypically high break rates. The potential for this bias cannot be

clarified without more complete information on 1906 pipe damage.

Regressions of the data were performed on both sets of data, and a combined set. The

best fit was found as follows: (a) the 1989 data was treated as one set, and a regression was performed to fit a line with zero intercept over the domain 0 to 5 inches of

displacement; (b) the 1906 data were treated as a separate set, and a regression was

performed to produce a best fit line over the domain 5 inches to 9 feet; (c) a bilinear

break rate curve resulted, as shown in Figure 9. A null hypothesis test indicates that a correlations exists with at least 95% confidence (Crow et al, 1960). These correlations and

resulting curve apply only to bell and spigot cast iron pipe with lead and oakum joints.

4.2 VULNERABILITY OF OTHER PIPE TYPES

Detailed damage data is unavailable for the other six classes of pipe. To develop break

rates for these other classes, the break rate for bell and spigot cast iron was multiplied by

a "relative vulnerability" factor R. Relative vulnerabilities were determined based on a review of the literature, as well as engineering judgment.

8
4.3 DOUBLE SPIGOT, HEAVY WALL CAST IRON PIPE

Relative vulnerability R for this class of pipe was arrived at by multiplying factors to account for joint rotational capacity (J), wall thickness (W), extra restraint (B for bolts),

and laterals (L):

R=}*W*B*L

The use of double spigot joints doubles joint rotation capacity, so J was assigned a value

of 0.5. Since AWSS pipe walls are 8/5 as thick as those of bell and spigot MWSS cast iron,

W was assigned a value of 0.625. It is difficult to assess that benefit of added restraint in

AWSS pipe. The section properties of restrained joints are only slightly greater than those

of unrestrained joints, so bolting is considered to add little overall pipe strength. B was

therefore assigned a value of 1.0. L was assigned considering the damage associated with

service connections in Marina District MWSS pipe in 1989. Approximately 25% of main

breaks in the Marina were associated with services. Since the number of laterals in AWSS

pipe is negligible next to that of MWSS, L was assigned a value of 0.75. R is therefore

approximately 0.25.

4.4 DUCTILE IRON PIPE WITH RIGID JOINTS

This type of construction was used in San Francisco between about 1960 and 1989. It was

assumed to be similar to pipe ductile iron pipe damaged in the in the Miyagi Prefecture

in the 1978 Miyagi-Ken-Oki earthquake. The failure ratios reported by Kubo and

Isoyama for ductile iron and cast iron water pipe were 0.04 and 0.17 failures per km,

respectively. The ratio of these figures equates with R. For simplicity, R has been

assigned a value of 0.25.

4.5 DUCTILE IRON PIPE WITH FLEXIBLE JOINTS

Hard data were unavailable on the relative performance of cement caulked joints as compared with lead/oakum joints. The ultimate compressive strength of the two materials

is probably comparable, although the strains at ultimate vary greatly. Lead flow

plastically while cement mortar will chip out as rotation occurs (ie, brittle failure). It is estimated that Field Lok Gaskets allow joints in bell and spigot ductile iron pipe to rotate

approximately twice as much as similar pipe with mortar-caulked joints. Therefore, a value of 0.125 has been assigned to R.

4.6 GAS WELDED STEEL PIPE

Hamada (1983) compared cast iron pipe breakage with steel gas pipe breakage in the 1983

Nihonkai-Chubu earthquake, and concluded that the rate of damage to cast iron pipe was

two to three times that in the case of steel pipe. Eguchi describes gas-welded steel pipe in

faulting regions as 30% as vulnerable as cast iron. In landslide, the factor is 61%, and in

liquefaction and lurching, 70%. Based on these observations, R = 0.50 was assigned.

4.7 RIVETED STEEL PIPE

Little data is readily available describing the performance of riveted steel pipe. Judging

from photos presented by Duryea, it appears that the failure mode of riveted pipe is shear

of the rivets. It is unlikely that significant local deformation can occur around rivet

holes because these are most likely fabricated from iron boiler plate. We consider that

9
riveted joints were designed to develop pipe body yield stresses with a marginal safety

factor. It was reasoned that riveted steel pipe would perform similarly to pipe

construction that immediately succeeded it (ie, gas-welded steel pipe) and therefore the same R = 0.50 was assigned.

4.8 ARC WELDED STEEL PIPE

Eguchi describes Grades A and B arc-welded steel gas pipe in fault rupture areas as 5.8%

as vulnerable as cast iron. In landslide, the factor is 11%, and in liquefaction and

lurching, 15%. The material properties of welded steel water pipe are fairly similar to those of contemporary gas pipe. Using these data, arc-welded steel water pipe was

assigned a relative vulnerability R = 0.125.

5 DISCUSSION

Break rate functions developed using the methods discussed here are presented in Figure

10. These relationships indicate a trend of break rate increasing from 0 to 6 breaks per

1000 feet of pipe as permanent ground displacement increases from 0 to 6 feet. The trend

and order of magnitude of damage tend to agree with Eguchi's data on pipe damage near

fault rupture in 1971 San Fernando. In that earthquake, damage ranged from 0.4 to 5 breaks per 1000 feet near fault offsets as fault displacement increased from 3 to 98

inches. The figures developed for the present study are somewhat larger than Eguchi's

figures for pipe damage in regions of liquefaction and landslide.

Hamada's data on the 1983 Nihonkai-Chubo earthquake indicate break rates in cast iron

gas pipe reach as high as 21 breaks per 1000 feet, but it may be supposed that the higher

magnitudes could result from stiffer joint construction. The order of magnitude is also

supported by the Tangshan earthquake data presented by Shaoping et al.

The high initial break rate agrees with Miyajima's conclusion that pipe damage can be

caused even by an average ground strain of less than 1 percent. Eguchi's relationship

between break rate and MMI shows a similar trend, with the logarithm of damage

increasing at a slower rate as MMI exceeds VIII.

6 CONCLUDING REMARKS

Damage data from the 1906 San Francisco and 1989 Loma Prieta earthquakes have been

used to estimate break rates for cast iron water pipe subjected to permanent ground

displacement. A bilinear curve was fitted to the data. The first segment (0 to 5 inches

displacement) was based on water pipe damage in the Marina District in the 1989 Loma

Prieta earthquake. The second segment (5 inches to 6 feet) was based on records of

damage to similar pipes damaged in the 1906 San Francisco earthquake.

Damage rates for other types of water pipe were developed by applying a relative

damageability factor, R, to the function developed for cast iron water pipe. The factors were developed for each type of water pipe used by the City of San Francisco for feeder

and distribution water mains. Where possible, the factors were based on data presented in

the literature. Where such data were unavailable, engineering judgment was employed to

10
estimate relative damageability. As a result, the damage functions for several different

types of San Francisco water pipe are similar bilinear curves differing by a factor R.

The major observation is that normalized pipe break rate is nonlinear with permanent

ground displacements. Relatively small displacements produce initial pipe breakage; at larger displacements, break rates increase at a smaller rate. A possible explanation for the

nonlinearity is that damage initiates at low magnitudes of permanent ground

displacement, breaking the original pipe network into shorter segments that are relatively

free to move with the surrounding soil. Relatively larger displacements are required to cause further breaks in the remaining intact network segments.

Data presented in the literature tend to verify the trend of relatively small displacements

causing significant initial pipe breakage, while larger displacements result in additional

breaks, but at a relatively smaller rate. The magnitude of break rates developed here

tend to lie within the range of break rates recorded for gas and water pipe in other

earthquakes under similar conditions.

Additional research is needed on this topic, including for example: (a) careful collection

of post-earthquake survey measurements of vertical and lateral displacements in areas of

liquefaction and/or high pipe breakage, and (b) small-scale laboratory experimental

investigation of pipe break as a function of displacement.

ACKNOWLEDGEMENTS

This work benefitted from data provided by Mr. Tom Dickerman (San Francisco Water

Department), and Mssrs. Andrew Nielsen and Steve Van Dyke (San Francisco Fire

Department - their cooperation is very much appreciated. The opportunity to participate

in the San Francisco Soils Study project, provided by Mr. Charles Ng. (San Francisco Dept.

of Public Works), Mr. Henry Taylor (HLA, Inc.) and Mr. Robert D. Darragh (Dames &

Moore) is sincerely appreciated. Discussions on aspects of this with Mssrs. Don

Ballantyne, Michael Laderman and Daniel Seidel (KJC, Inc.) are also acknowledged and

appreciated. Lastly, portions of this work were supported by grants from the National

Center for Earthquake Engineering, SUNY-Buffalo, which support is very much

appreciated.

REFERENCES

Ahmed, I., 1990, "Pipeline Response to Excavation-induced Ground Movements," Ph.D.

dissertation, Cornell University

Crow, E.L., Davis, F.A., and Maxfield, M.W. (1960) Statistics Manual, Dover Publications,

New York.

Duryea, E., CD. Marx, F. Riffle, A.L. Adams, and W.W. Harts, 1907, "The Effects of the

San Francisco Earthquake of April 18th, 1906, on Engineered Constructions," ASCE

Transactions, Vol LIX, Paper 1056

11
Eguchi, R. T., 1981, "Earthquake Vulnerability of Water Supply Systems," Lifeline

Earthquake Engineering, the Current State of Knowledge 1981, Am. Soc. Civil Engrs., New

York.

Eguchi, R. T., 1983a, "Seismic Risk and Decision Analysis of Lifeline Systems," Lifeline

Earthquake Engineering: Performance, Design and Construction, Am. Soc. Civil Engrs.,

New York.

Eguchi, R. T., 1983b, "Seismic Vulnerability Models for Underground Pipes," Earthquake

Behavior and Safety of Oil and Gas Staorage Facilities, Buried Pipelines and Equipment,

Am. Soc. Mech. Engrs., pp 368-373

Hamada, M., 1989, "Damage to Buried Lifelines due to Liquefaction-Induced Ground

Displacements," Proceedings of the Third U.S.-Japan Workshop on Earthquake Disaster

Prevention for Lifeline Systems

Harding Lawson Asssociates, Dames & Moore, Kennedy/Jenks/Chilton, and EQE

Engineering, 1991, "San Francisco Liquefaction Study," a report prepared for the City and

County of San Francisco Bureau of Engineering

Katayama, T., K. Kubo, and N. Sato, 1975, "Earthquake Damage to Water and Gas

Distribution Systems", Proceedings of US National Conference on Earthquake Engineering

1975, pp. 369-405

Kubo, K., and R. Isoyama, 1980, "Damage to Buried Utility Pipes in the 1978 MiyagikenOki Earthquake," Proceedings of the Seventh World Conference on Earthquake

Engineering, Vol 8, pp 225-229

Miyajima, M., and M. Kitaura, 1989, "Effects of Liquefaction-induced Ground Movement

on Pipeline," Proceedings of the Second U.S.-Japan Workshop on Liquefaction, Large

Ground Deformation and their Effects on Lifelines, NCEER, pp. 386-400

O'Rourke, T.D., Grigoriu, M. and Khater, M., 1985, Seismic Response of Buried Pipelines,

Pressure Vessel and Piping Technology 1985 - A Decade of Progress, ed. by C. Sundararajan,

Pressure Vessels and Piping Deivision, Am. Soc. Mech. Engrs., New York.

O'Rourke, T.D. and P. A. Lane, 1989, "Liquefaction Hazards and their Effects on Buried

Pipelines," NCEER-89-0007

O'Rourke. T.D., T.E. Gowdy, H.E. Stewart, and J.W. Pease, 1990, "Lifeline Performance and

Ground Deformation in the Marina During 1989 Loma Prieta Earthquake," Proceedings of

the Third Japan-U.S. Workshop on Earthquake Resistant Design of Lifeline Facilities and

Countermeasures for Soil Liquefaction, NCEER

Schussler, H., 1906, "The Water Supply of San Francisco, California, Before, During and

After the Earthquake of April 18, 1906 and the Subsequent Conflagration," Spring Valley

Water Company

Shaoping, S., A. Zongpei, and H. Ganyl, 1983, "Pipeline Damage and its Relationship with

Joints", Proceedings of 4th National Conference on Pressure Vessel and Piping

Technology, pp. 374-377

12
Figure 1: Damage data for shaking effects only

(after Eguchi 1983, appended by Harding Lawson et al , 1991)

(Numerals indicate maximum

fault offset, in inches)

150 300 450

DISTANCE FROM PREDOMINANT

LINE OF FAULT RUPTURE (FEET)

600

Figure 2: Effect of fault rupture

(Eguchi, 1983)

13

c) Zone B

Figure 4: 1906 ground movements in Mission Creek

(O'Rourke, 1989)

Figure 5: 1989 Marina settlement contours

(O'Rourke, 1990)

15
Figure 6: Double spigot joint

Figure 7: Field Lok Gasket

(U.S. Pipe)

LEGEND: WATER SYSTEM

I 1 1

I I 1

1

1

1

1

1

1

1

1 I 1 1 1 1 I r

Figure 8: 1989 Marina water system breaks

16
o

ooo

0>Q.

(0£

CD

O

Q.

20 40 60 80 100

Permanent Ground Displacement inches

120

Figure 9: 1906 and 1989 cast iron water pipe damage

(D S

o

o

0)

OSS

m

o

a. a.

10 20 30 40

Permanent Ground Displacement inches

Figure 10; Estimated water supply pipe damage

17

A PROPOSAL OF PRACTICAL EARTHQUAKE RESPONSE ANALYSIS

METHOD OF CYLINDRICAL TUNNELS IN SOFT GROUND

by Yukio Shiba and Susumu Okamoto

Research Engineer, Earthquake and Wind Engineering Group,

Technology Research Center, Taisei Corporation

ABSTRACT

This paper proposes a simple method for the earthquake response analysis of the cross section of cylindrical tunnels in homogeneous soft ground. In this method, the tunnel lining is modeled as a simple ring-on-elastic-support and is subjected to two kinds of seismic forces, i.e. the ground displacements and the ground shear stresses which are estimated from the freefield earthquake response. The seismic stresses induced in the tunnel lining are thus described

by mathematical formulae that can be calculated easily by means of a personal computer.

Accuracy of the method is almost comparable to that of FEM. For designers convenience,

approximate formulae for estimating roughly the seismic stresses are also proposed in this

paper.

INTRODUCTION

In recent years, most urban tunnels for lifeline facilities and transportation systems in

Japan have been constructed by shield tunneling method, which forms a cylindrical tunnel

fabricating segmented lining members in a tunnel boring machine. Because of effective use

of underground space, the diameter and depth of these tunnels tend to be large and deep.

Until now, the influence of earthquakes on tunnels in soft ground has been discussed

mainly with regard to the longitudinal direction. However, unhke buried pipes with small

diameters such as gas pipelines, it is also necessary to examine the seismic stability of the

cross section of tunnels with large diameters, which are supposed to be largely deformed by

shear strain in soft ground during earthquakes. In these days, FEM (Finite Element Method)

or the Seismic Deformation Method, which uses a beams-and-springs model of tunnel-ground

systems, are employed as earthquake response analysis methods for cross sections of very

large and important tunnels. However, since these analysis methods are time and labor

consuming, and moreover, since tunnels are thought to be safe from earthquakes, usually

the earthquake response analysis of cross sections is not executed in the design process

for ordinary shield tunnels. It is desirable to develop a rational and yet simple method of

analysis. In this paper, a simple method to analyze the earthquake response of cross sections

of cyHndrical tunnels is proposed.

19
METHOD OF EARTHQUAKE RESPONSE ANALYSIS

Object of Analysis

The object of earthquake response analysis in this paper is the cross section of a cylindrical tunnel as the one shown in Fig.l. The tunnel has radius R and its center is located

at depth H. The surrounding ground consists of two layers: a soft surface layer and a rigid

base layer. The surface layer, with thickness Hg, is assumed to be homogeneous.

Model of Tunnel-Ground System

Fig. 2 shows the general concept of the proposed method. The tunnel hning is modeled

as an uniform ring with unit length along the tunnel axis. In the case of a shield tunnel, the

tunnel lining, which is segmented in the circumferential direction, can also be modeled as a uniform ring with an equivalent rigidity taking the joint effect into consideration.

The interaction spring, which represents interaction effect between the tunnel lining and

the surrounding ground, is distributed continuously around the ring. The interaction spring

in the present model is not of the Winkler type but of the coupled type, which mutually

acts on the radial and tangential directions of the ring; the characteristics of the interaction

spring are detailed later. The model of the entire tunnel-ground system is therefore a ringon-elastic-support.

Seismic Forces

From the results of many earthquake observations on underground structures and shake

table tests on their scale models, it has been concluded that seismic stresses induced in un- derground structures are governed principally by surrounding ground strain, i.e. differential

ground displacement. Based on this idea, the Seismic Deformation Method, which is the most

widely used earthquake response analysis method for underground structures, calculates seismic stresses and deformations by statically subjecting the structure model, supported with

interaction springs, to ground displacement. According to the Seismic Deformation Method,

Uh Ground Surface

Displacement

He

Tunnel Lining

E,A,I, AT

Soft Layer

Base Layer

Fig. 1 Object of Earthquake Response Analysis

20
seismic stresses in a cylindrical tunnel lining can be obtained by statically displacing the

end of the interaction spring of a ring-on-elastic-support model to the position of the ground

displacement as determined from the free-field earthquake response.

However, the Substructure Method [Ref. 3] which is an efficient method for soil- structure interaction analysis, suggests theoretical seismic forces for underground structures

as follows:

(1) In case of using free-field motion, seismic forces should be the product of the displacement and the interaction spring constant, and the ground stress along the position of

the tunnel-ground interface.

(2) In case of using scattered-wave motion (i.e. motion of the free surface along the

position of the tunnel-ground interface when considering that the tunnel has been removed),

the seismic force should only be the product of the displacement and the interaction spring

constant.

It is obvious that although the Seismic Deformation Method uses free-field motion, it does not take ground stress into consideration.

The present method takes both ground displacement and stress into account as seismic

forces. As shown in Fig.2, these seismic forces are determined from earthquake response

displacement and shear stress along the tunnel-ground interface in the free field. Ground

displacement acts on the ring through the interaction spring, and stress acts directly on the

ring.

Stress \^^^in Ground

Tunnel / ^ Position-.

Disp. in Ground

Earthquake Response of Free Field

Seismic Forces

Stress iTM Stress Components \^S't'i^ Ground

Tunnel (Lining

] interaction

;Ringy Spring

Wg

Disp. Components

Ring - on - elastic - support Model

and Seismic Forces

Fig. 2 Concept of the Proposed Method

21
Assumptions and Restrictions

In addition to the assumptions included in the modehng process of the tunnel-ground

system, the following assumptions are used to formulate the tunnel behavior during earthquakes :

(1) The theory of curved beam is used for the analytical description of the ring behavior.

(2) The soft surface layer is supposed to oscillate in the 1st mode

(3) The influence of inertia force of the tunnel hning on the tunnel stresses is supposed

to be negligible.

(4) The nonhnear characteristics of lining and soil are not taken into consideration.

(5) The depth of tunnel crown should be much larger than the diameter of the tunnel,

and the tunnel invert should not be close to the rigid base layer.

For the description of the ring behavior during an earthquake, the following notation is

Hg : Thickness of the surface layer.

G : Shear modulus of the surface layer.

p : Mass density of the surface layer. u : Poisson's ratio of the surface layer.

Uh : Displacement amplitude at the ground surface. * * H : Depth of the tunnel center.

R : Radius of the tunnel.

E : Young's modulus of the lining.

A : Sectional area of the curved beam (per unit length along the tunnel axis).

/ : Moment of inertia of the curved beam (per unit length along the tunnel axis).

K : Section modulus of curved beam defined as Eq.(l).

FORMULATION OF TUNNEL BEHAVIOR

Notations

used.

(1)

where y expresses the distance from the centroid of the cross section.

The following notation is shown in Fig. 3.

(f)

: Angle from crown of the ring.

w{<f)),v{(f>) : Displacement in radial and tangential directions of the ring; subscript g of

w and V denotes displacement in the free-field.

22
Fig. 3 Coordinate System of Ring

M(0), N{<f>), Q{(f>) : Bending moment, normal force and shearing force in the ring per

unit length along the tunnel axis, respectively.

<r(<^),r(<^) : Seismic forces in radial and tangential directions acting on the ring.

Subscript g expresses the ground stress and subscript i expresses the seismic force as the product of the displacements and the interaction spring constants.

The positive directions of (f>, w, v, M, N^Q.a^r are also shown in Fig. 3.

Governing Equations

The following equations are derived as the governing equations of the ring from equilibrium and stress-strain equations.

M=-E-A'K-{—^w) (2.a)

N = E-A

N = -^-R-a,-R-a, (2.d)

Q = -j^ + R-T, + R^Ti (2.e)

Modeling of Interaction Spring

Modehng of the interaction spring is very important to obtain the displacements and

stresses in the ring using Eqs.(2.a)~(2.e). Currently there is not an appropriate model of

the interaction spring. Based on the theory of elasticity, a coupled type interaction spring

model is proposed here.

23
Consider the cylindrical cavern in the homogeneous infinite media when the tunnel

has been removed as shown in Fig. 4. The stress- displacement equations for the interaction

spring model are derived from the relation between the displacements along the cavern free

surface and the reactions of the homogeneous media. Suppose that the radial and tangential

displacements along the cavern surface are expressed as a Fourier series as follows,

^{<f>) = Y1 ^n- sin(n • (f>) n=l

oo ^{^) = SI ^^n • COs(n • (f))

(3.a)

(3.b)

n=0

where the symmetric condition of the displacement distribution in the cavern surface has been

considered, and k;„ and express Fourier components of radial and tangential diplacements

in the nth Fourier mode. The reactions of the homogeneous infinite media are derived using

the theory of Airy's stress functions. Eqs.(4.a) and (4.b) are the results using the restriction

that the horizontal stress component in the first Fourier mode derived by reactions <t,- and

T, is equal to zero.

n )

• sin(n • (f)) n=l

oo

ri{(l>) = E {I<n • Vn + K ^n) ' COs( <t>)

(4.a)

(4.b)

n=0

Kn and K'^ correspond to the interaction spring constants which are defined for each

Fourier mode of displacements along the cavern surface as follows,

2G :n = 0

:n = 1 2n + 1 - 2u{n + 1)

3-4i/

(5.a)

Homogeneous

Infinite Media

Reactions

W '

Displacement

Fig.4 Tunnel-Ground Interaction

( The second Fourier Mode

)

24
0n + 2-2i/(n + l)

3-4i/

:n = 0,1

:n > 2

(5.b)

In the Seismic Deformation Method, the Winkler's springs are generally used as the

interaction springs. However the springs proposed here (i.e. coupled type springs) have two

remarkable different characteristics compared with the Winkler's springs:

(1) Spring constants and K'^^ are defined for each Fourier mode of displacement.

(2) By enforcing radial displacement on cavern surface, not only radial reactions but also

tangential reactions occur in the homogeneous infinite media. Also, by enforcing tangential

displacement, the radial and tangential reactions occur. In case that K'^ is equal to zero, mutual effects of radial and tangential springs are ignored. Thus, in this condition interaction springs are equivalent to the Winkler's springs.

The results using the Winkler's springs are described later.

Formulation of Deformations and Stresses in Tunnel Lining

The displacement and shear stress distribution in the free field for the fundamental

oscillation mode as shown in Fig. 5 are given by Eqs.(6) and (7),

U{z) = UH-cos{y^) (6)

The radial and tangential components of the ground displacement and the ground shear

stress at the position of the tunnel are derived as a function of the angle 4> from Eqs.(6) and

(7) as shown in Eqs.(8.a)~(8.d).

Uh

Fig. 5 Displacement and Stress in Free Field

under 1st Mode Vibration

25
"^gW = • cos I

• sin

rr !

tt {H - R cos<f>) \

Vg{<f>) = Uh ' cos

I

^ — J

• cos (f)

IT • {H — R • cos (j))

rg{<f>) =

T'G-Uh

2Ha

sin

2H.

sm 1 —

K • [H — R - cos (f)) 2H9

{H - R- cos <f))

sin 2(?!)

cos 2(f>

(8.a)

(8.b)

(8.C)

(S.d)

Deriving the seismic forces cr,- and r,, the ground displacements and u„ in Eqs.(4.a)

and (4.b) are replaced by the difference between the ground displacements and the displacements of the ring, {wgn — Wn) and {vgn — Vn), respectively. Here Wgn and Vgn express the

results of Fourier series expansion which include the first kind Bessel functions of Wg and Vg

in Eqs.(8.a) and (8.b). By substituting cr, and r,-, and the Fourier series expansion of ag and

Tg into Eqs.(2.a)~(2.e), the radial displacement of the nth Fourier mode of the ring, Wn, can be expressed as follows.

Fn

Uh ~ n6 - (2 - «^n)n4 + + 2k^0"' - '^^^ + (1 + '^)^" + ' ^n)

Where, = . { {n^ + n -f AC . + ^;)} • {{^n - (3'n)

• Jn-1 + • (^) • Jn-2}

(9.a)

Pn =

' (_i)(n+i)/2 . cos(-^^):„ is odd

(-ir/^'sin(^^) :n is even

^ 2Hg^

R-G

E- A'K f3n =

R' • Kn

E-A-K E- A-K

(9.b)

(9.C)

(9.d)

In the above equations, J„ denotes the nth mode of the first kind Bessel functions

Jn(7r • R/2Hg). Substituting Wn into Eqs.(2.a)~(2,e), the displacements and stresses in the

ring are derived as follows.

v{4>)

jj^

' sin(n • (f>) n=l

(lO.a)

TT • R.

{Jn+2 - Jn-2)}} • COs(n • 0) (lO.b)

26
E-A-K-U,

-^^^ -l)-;^-sm(n.0)

n=2

= 2. n . (n^ - 1) cos(n . 0)

oo

(lO.c)

n=2

(lO.e)

n=l (7^

^2^) • ('^'^+2 - Jn-i)]] • sm(n .

Approximate Formulae for Calculation of Seismic Stresses

c o

E^s.(10-c)~(10.e) are the accurate solutions of the stresses in the tunnel. The inclusion

of Bessel functions m these solutions makes it a Httle difficult to calculate the stresses in

the tunnel. Therefore approximate formulae, that are easier to compute than the accurate

solutions, are proposed by simpHfying Eqs.(10.c)~(10.e) mathematically.

The series expansion of the first kind Bessel functions is given by,

oo

where x = % • R/2Hg

^21 b)

Generally the depth of the tunnel crown is much larger than the diameter of the tunnel. Thus X in Eq.(ll.b) is neghgible compared to one and the terms of (x/2)^, (x/2)^... in

Eq.(ll.a) are neglected. After this approximation, only Jq and Ji in Bessel functions are

effective in Eqs.(10.c)~(10.e),

Jo(^) « 1 (12.a)

_ ,7r • i?. 1 ,T • R.

2^) " 2

• ( (12.b)

M^)''0 >=>2 (12.C)

In Eq.(13) /c is defined as an approximate formula using radius i?, area A and moment

of inertia / of the ring.

^-j:^ (13)

In case that the term including k is negligible compared with the other terms, it can

also be neglected.

27
After these mathematical approximation, only the terms of the 2nd Fourier mode in

Eqs.(10.c)~ (lO.e) are effective for calculating the seismic stresses in the ring. Thus the maximum bending moment and normal force occur at the diagonal direction of the tunnel, and

the maximum shearing force occurs at the crown and invert of the tunnel. Eqs.(14.a)~(14.c)

express the maximum seismic stresses in the tunnel lining as given by the approximate

formulation.

Qmax —

J-N'max =—

37r • EI

2R H,

Stt • EI

Uh-

•H, 2H,

37r • EI

Uh

. ,r-H

H,

)-C

)-C

.1 c

c =

4:{l-u)-G-R'

(3 - 2i/) • G • + 6(3 - 4z/) • • /

(14.a)

(14.b)

(14.C)

(14.d)

Eqs.(14.a)~(14.c) correspond to the seismic stresses in the ring for the case in which

the ground shear strain is uniform (i.e. displacement distribution of the free field is hnear).

The value of the uniform strain is equal to the shear strain at the position of the center of

the ring when the ground is oscillating in the fundamental mode.

VERIFICATION OF THE PRESENT METHOD BY FEM

Analysis Cases

In order to verify the present method, comparative analyses with the FEM(Super

FLUSH) have been carried out. Four cases, as shown in Table 1, have been analyzed.

Case 1 is the fundamental case. In case 2, the tunnel is located close to the base layer. In case 3, the diameter of the tunnel is changed to a small one. And in case 4, the surface layer

is made more rigid.

In FEM, only the left half of the area was analyzed considering the symmetry of the

system, and the tunnel lining was modeled by 36 beam elements. The material properties of

the tunnel lining are listed in Table 2. Fig. 6 shows the FEM meshes. The input earthquake

for each case is a harmonic wave with natural frequency equal to that of the 1st oscillation

mode of the surface layer, and with amplitude of 100 Gals at base layer outcrop. In the

present method, the displacement amphtude at the ground surface, Uh, as shown in Fig. 7,

was determined from the results obtained by FEM (see also Table 3).

Table 1 Analysis Cases

Tunnel Surface Layer

No. Diameter

2R

(m)

Thickness

h

(m)

Depth

H

(m)

Thickness

Hg

(m)

Density

P , (t/m')

Velocity

Vs

(m/s)

Poisson's Ratio

V

Damping

Factor Natural Frequency

(Hz)

1 16 0.8 25 50 1.6 120 0.45 0.02 0.6 2 16 0.8 40 50 1.6 120 0.45 0.02 0.6 3 6 0.3 25 50 1.6 120 0.45 0.02 0.6 4 16 0.8 25 50 1.8 240 0.40 0.02 1.2

28
Table 2 Material Properties

Properties

Tunnel

Lining Base

Layer

Mass Density ( t / ) 2.6 2.0

Young's Modulus ( G Pa

)

34.3 0.86 S - wave Velocity ( m/ s

)

2370 400

Poisson's Ratio 0.17 0.35 Damping Factor 0.02 0.02

60 m

H

1 1

25 m

16 m

1

40 m

16 m

520 nodes

480 elements

( a ) Case - 1 , Case - 4

518 nodes

474 elements

(b) Case -2

6 Orn- ——

h-1—

'

1—

m —1

1

1 H

1

25 m

6m

Fig. 6 FEM Meshes

551 nodes

510 elements

( c ) Case - 3

29
t— Uh = 0.2500 m

50 m •

N

U

/

h

—

r

-4

1

25 m

16 m

60 m -I

Fig. 7 An Example of Displacement Diagram by FEM (Case 1)

Results

Fig. 8 illustrates the comparison of stress distributions induced in the tunnel lining

obtained by the proposed method and by the FEM. The maximum stresses are summarized

in Table 3. From Fig. 8 and Table 3, the following can be noted:

(1) Except in Case 2, both the maximum values and the distribution patterns of seismic

stresses calculated by the proposed method show good agreement with those obtained by

FEM. The difference in maximum values between the two methods is of a few percents.

(2) In Case 2, in which the tunnel is located close to base layer, the shearing force at a region in the neighborhood of the tunnel invert differs with that obtained by FEM. The

reason for the difference is supposed to be that the interaction spring in the proposed method

is modeled uniformly along the tunnel ring, while kinematic interaction effects, in fact, vary

with distance between the tunnel and the surface/bottom boundary of the ground layer.

Therefore, when using the present method, it is necessary to pay attention to the location

of the tunnel.

(3) In case a Winkler type interaction spring is used for the analytical model, as illus- trated with broken lines in Fig. 8, normal force in all cases, and other stresses in Case 4, were underestimated. This indicates that interaction forces which mutually act on radial

and tangential direction of the ring have considerable influence on seismic stresses, and that

the coupled type interaction spring used in the proposed method is quite appropriate.

(4) Approximate formulae underestimate seismic stresses. According to the detailed

examination of the approximate formulae, they underestimate seismic stresses at most 20%

of those by exact solutions (10.c)~(10.e) [Ref. 1, 2]. Although the approximate formulae

have hmits of accuracy, they are of great use for making rough estimates.

30
Legend

FEM

Proposed

Method

.... Winkler's

Hypothesis

Case -

Case -2

Case -3

Case -4

kN/m

0 1000

314kN-m/in

kN-m/m <// 0 200

kN/m

0 100

372kN- m/m

mikif/m.

kN/m

0 1000

1754kN/m

kN/m

0 2000

kN/m

0 400

Bending Moment Shearing Force Normal Force

Fig. 8 Comparison between the Present Method and FEM

31
Table 3 Comparison of Tunnel Stresses

Ground Response Tunnel Stresses Case

No.

Acc. Disp.

Uh

Max. Bending Moment

( kN • m / m

)

Max. Shearing Force (kN/m)

Max. Normal Force (kN/m)

(Gal) (cm) FEM Proposed Approx. FEM Proposed Approx. FEM Proposed Approx.

1 367 25.00 23 1

3

2365

( 1.02)

2240

( 0.97

)

608

624

(1.03) 560

(0.92) 1470

1458

( 0.99

)

1312

( 0.89

)

2 371 25.37 3214

3091

(0.96)

3058

(0.95) 951 784

( 0.82

)

764

(0.80) 1784

1838

(1.03) 1791

(1.00)

3 368 25.18 314 324

(1.03)

318

( 1.01

)

216

221

(1.02) 212(0.98)

529

516

(0.98)

496

(0.94)

4 178 2.77 372

363

(0.98) 333

(0.90) 98

97

(0.99) 83( 0.85

)

676

643

(0.95) 587(0.87)

( ) : Ratio to F E M

CONCLUSIONS

A simple method for earthquake response analysis of cross sections of cylindrical tunnels

in homogeneous soft ground has been developed. The general idea and peculiarity of this

method can be summarized as follows :

(1) The tunnel-ground system is modeled simply as a ring-on-elastic-support.

(2) The interaction spring as elastic support in the model is not of the Winkler-type

but of the coupled type, which mutually acts on the radial and tangential direction of the

ring. In case that the Winkler-type ground spring is employed in the model, seismic stresses,

especially normal force, in the tunnel are underestimated.

(3) The seismic forces for the model are the displacement and shear stress evaluated from

the free-field earthquake response along the position of the tunnel-ground interface, whereas

only the displacement is taken into account in the Seismic Deformation Method, which is the most widely used earthquake response analysis method for underground structures.

(4) The deformation and stresses in the tunnel are thus described by mathematical

formulae using a series of Bessel functions, that can be calculated easily by means of a

personal computer.

(5) Accuracy of the method is almost comparable to that of FEM under the condition

that the depth of the tunnel crown is much larger than the diameter of the tunnel and that

the tunnel is not too close to the rigid base.

Besides the above-mentioned exact solution of seismic stresses, approximate formulae

are also presented. Although the approximate formulae underestimate the stresses by at most 20% of the exact values, they are useful for making rough estimates.

32
FUTURE DIRECTIONS

As a result of this study, a method to examine the seismic stability of cross sections of

cylindrical tunnels was developed for a considerably idealized tunnel-ground system.

In order to establish a seismic design method of cross sections of large scale sheild tunnels, it is necessary to advance the study to a more practical stage considering the following:

(1) In this study, the surface layer of the tunnel-ground system is assumed to be elastic

and homogeneous. In practice, however, behavior of the ground during large earthquakes

shows non-linear characteristics due to material non-linearity of the soil. Furthermore, when

a shield tunnel with large diameter and large depth at urban site is planned, the case of

the cross section of the tunnel lying across a boundary line between soft Alluvial and hard

Diluvial stratum is often encountered. It is therefore necessary to improve the proposed

method into a more practical one as far as it is preserved simple.

(2) In addition to improving the earthquake response analysis method, we should ex- amine the characteristics of seismic stresses induced in the tunnel lining in comparison with

static stresses due to earth and water pressures, and discuss the total stability of the tunnel.

ACKNOWLEDGEMENTS

This study was carried out as one part of "A Cooperative Research in Development

of Seismic Design of Underground Structures." The authors express their sincere appreciation to the cooperative research colleagues : Public Works Research Institute, Advanced

Construction Technology Center, Okumura Corporation, Kajima Corporation, Konoike Construction Corporation, Shimizu Corporation, Tobishima Corporation, Hazama Corporation,

and Fujita Corporation, for their useful advises and animated discussions.

REFERENCES

1) PWRI, ACTEC, Okumura Corporation, Kajima Corporation, Konoike Construction

Corporation, Shimizu Corporation, Taisei Corporation, Tobishima Corporation, Hazama

Corporation, Fujita Corporation, "Development of Seismic Design of Underground Structures", Cooperative Research Report of PWRI, 1991.

2) Shiba, Y., Okamoto, S.,"A Practical Evaluation Method of Seismic Stresses Developed in the Cross Section of Shield Tunnels," Proceedings of Japan Society of Civil Engineers,

(submitted).

3) Wolf, J. P.,"Dynamic Soil-Structure Interaction," pp. 369~375, Prentice- Hall, 1985.

33

VISUAL INFORMATION SYSTEM

FOR SEISMIC GROUND HAZARD ZONING

Ken-ichi TOKIDA", Hideo MATSUMOTO''' and Yasushi SASAKI

Earthquake Disaster Prevention Department

Public Works Research Institute

Ministry of Construction

Tsukuba Science City, Japan

ABSTRACT

Because most lifeline facilities are installed underground and have the potential

to be damaged by ground movement during earthquakes, seismic ground hazard

zoning is very effective for understanding and estimating the damage of

underground structures over a large region.

Seismic zonation in the past has been generally done for only a certain magnitude

of seismic intensity of an area. It usually does not consider different magnitudes

of earthquakes and locations of epicenters. A system which is capable of

assessing the ground hazard against any earthquake which might affect the area is

very useful for making a rapid inspection and for implementing urgent restoration

measures against damage to structures. This is because information about seismic

ground motion and ground hazard is essential to understanding the damage to

buried structures.

In this paper, the dynamic visual information system for seismic zonation of

ground hazard which is being developed at the Public Works Research Institute

(PWRI) is introduced.

DHead, Ground Vibration Division, PWRI

2) Research Engineer, Ground Vibration Division, PWRI

3) Director, Earthquake Disaster Prevention Department, PWRI

35
INTRODUCTION

Because damaging earthquakes affect structures over a wide area when they hit

urban regions, it generally takes a considerable amount of time and labor to

understand the damaged state of facilities immediately after the occurrence of

large earthquakes. Correct information on damage should be gathered quickly to

take action as soon sa possible for restoration just after an earthquake. In

addition, the rapid collection of useful information from various information

transferred in a confused state is necessary. The type and cause of the damage

need to be estimated and to given to the people who work on damage restoration.

For this purpose, a visual display of the distribution of the seismic intensity in

an area, even though it might be an estimated one, and the result of assessed

ground hazard is thought to be a very effective aid to rapid restoration work

just after an earthquake.

Although the underground structures for lifeline systems such as water pipes, gas

pipes, and so forth may be severely damaged during earthquakes, it is difficult to

directly find the damage because the structures are buried in the ground. It is

necessary and effective to estimate the damage of underground structures

indirectly with use of ground hazard zoning because the structures are easily

affected by the dynamic behavior of ground. Because the causes of damage to

underground structures are seismic ground motion, soil liquefaction and so on,

the zonation of ground motion and ground hazard is effective for evaluating the

hazard of lifeline systems extensively.

In this paper, the seismic ground hazard information system, which is being

developed to estimate the ground hazard and damage of underground structures

quickly and correctly with use of a computer system, is introduced. The system

is being developed as a pilot-system to investigate the usefulness of

visualization methods in sieving correct information effectively out of various

information which is reported just after the event. This is done by using a digitized map which has various information such as ground and structure

condition, ground hazard, structural damage and location of structures.

SEISMIC INFORMATION RELATED TO GROUND HAZARD

The purposes of establishing the information system of seismic ground motion and

hazard are twofold (see Table. 1):

1. To make possible the urgent and rapid inspection and restoration of

earthquake hazards just after an earthquake. Then, action can be taken

based on the actual or rationally estimated distribution of seismic ground

motion, and actual or rationally estimated ground hazard and actual damage

of structures.

2. To be utilized for strengthening the structures against future earthquakes

based on the rationally estimated distribution of seismic ground motion,

ground hazard and damage of structures.

36
Although there are several kinds of indices of earthquake ground motion and

hazard types, the ones of interest in this study are those related to the

earthquake-induced damage of structures, especially underground structures.

They are as follows:

1) Seismic intensity of ground motion.

2) Soil liquefaction.

3) Lateral ground spread induced by soil liquefaction.

The flow of seismic information of ground motion, ground hazard and structure

damage during the earthquakes can be summarized as shown in Fig. 1. The topics

related to the seismic information in this study can be classified as follows:

1) Fundamental data of earthquake and induced-ground motion and hazard.

2) Estimated data of seismic ground motion and hazard.

3) Quantitative estimation methods of seismic ground motion and hazard.

4) Data base needed for seismic zoning of ground hazard.

5) Actual data of earthquake-induced damage of (underground) structures.

6) Quantitative estimation methods of earthquake-induced damage of (underground) structures.

7) Data base needed for estimating damage of structures by ground hazard.

In this paper, the research results on the above subjects of 1) to 4) will mainly

be shown.

Fundamental Data of Earthquake and Induced-Ground Motion and Hazard

The information related to seismic ground motion and hazard which can be

recorded and collected just after an earthquake can be considered as follows.

1) Epicentral location of actual or estimated earthquake.

2) Magnitude of actual or estimated earthquake.

3) Seismic ground motion recorded by seismographs.

4) Ground hazard found at the site.

Because the location and Richter-Scale Magnitude of an earthquake are reported

in Japan by the Japan Meteorological Agency (JMA) just after an earthquake, these

fundamental data of an earthquake can be obtained easily through mass media.

When the earthquake observation system is improved as an on-line system, the

seismic ground motion records can be obtained without delay just after an

earthquake and used for actual seismic zoning of ground hazard. Furthermore,

the ground hazard which is estimated by indirect information can be corrected

with use of the actual hazard which is observed at the site and reported after the

earthquake.

Estimated Data of Seismic Ground Motion and Hazard

Although the fundamental data of an earthquake and the recorded ground motion

37
are very useful, they can not necessarily yield enough information on the ground

motion at every site of interest. Thus it is necessary to supplement the

fundamental information with analyzed data for urgent and rapid inspection and

restoration of earthquake-induced damage of structures. The information related

to ground hazard which is needed and useful to supplement the fundamental

information for restoration just after an earthquake can be classified as follows:

1) Seismic ground motion estimated at a site of interest in an area and its

distribution.

2) Soil liquefaction potential at a site of interest in an area and its

distribution.

3) Potential magnitude of lateral ground spread by soil liquefaction and its

distribution.

Quantitative Estimation Methods of Seismic Ground Motion and Hazard

Reasonable methods for analyzing the original data from of an earthquake and the

ground condition have been investigated and established. The following methods

are necessary for estimating the secondary information quantitatively.

1) Method for estimating the attenuation of seismic ground motion.

2) Method for estimating the soil liquefaction potential.

3) Method for estimating the lateral ground flow induced by soil liquefaction.

Data Base Needed for Seismic Ground Hazard Zoning

It is necessary to establish a data base to indicate and analyze the original

information before an earthquake occurs. The following data base should be

established for seismic ground hazard zoning:

1) Mapping data which draw the fundamental information such as the coastline,

boundaries of cities, locations of highways and rivers and so on.

2) Ground group information to estimate the seismic ground motion and soil

liquefaction potential.

3) Soil profile, geology and topographical ground condition to estimate the

soil liquefaction potential.

4) Contours of elevation to estimate the lateral ground spread by soil

liquefaction.

Attenuation of Seismic Ground Motion

The maximum acceleration of the ground surface can be estimated with the use of

equation (1) according to the ground group at the site of interest [Ref. 1] .

METHODS TO ESTIMATE QUANTITATIVE GROUND HAZARD

- 87.4x10'

232. 5x 10' ^ 403. 8x 10'

,0. 2 1 I5M [Ground Group 1]

[Ground Group 2]

[Ground Group 3]

,,31 3r.-i X (A +30)

- 1 , 2 13

(1)

38
where a m^x is maximum acceleration of the ground surface (gal), M is the

Richter-Scale Magnitude of an earthquake and A is the epicentral distance (km).

The Richter-Scale Magnitude is reported by JMA just after an earthquake and the

epicentral distance can be calculated from the location of an earthquake. The

Ground Groups 1, 2 and 3 are rock or diluvial ground, alluvial ground, and soft

alluvial ground or reclaimed ground, respectively [Ref. 2] .

The Seismic Intensity on the JMA scale is also estimated based on the maximum

acceleration of the ground surface calculated with the use of equation (1) as follows.

(gal) 0.8 ~ 2.5 ~ 8.0 ~ 25 — 80 ~ 250 ~ 400

Seismic Intensity

Soil Liquefaction Potential

The sandy layers at a site of interest with the following conditions can be

considered to be vulnerable to liquefaction during earthquakes, and their

liquefaction potential should be examined [Ref. 3] :

1) The layer is a saturated alluvial sandy layer.

2) The layer is within 20 m from the ground surface.

3) The ground water level is within 10 m from the ground surface.

4) The DcQ-value is between 0.02 mm and 2.0 mm for grain size accumulation curve.

As for sandy soil layers judged to be vulnerable to liquefaction, liquefaction

potential can be examined based on the liquefaction resistance factor Fl defined

by the following equation (2) [Refs. 2 and 3] . Soil layers with a liquefaction

resistance factor Fl less than 1.0 are judged to liquefy during the earthquake

considered.

Fu = R / L (2)

where Fl is the liquefaction resistance factor, R is the resistance of soil

elements to dynamic loads and L is the dynamic load applied to the soil elements.

R and L are estimated simply with use of the following equations:

R = Ri +R2 +R3 (3)

Ri = 0.0882^^N/((7 v'+0.7 ) (4) — 0.19 (0.02mm ^Deo^ 0.05mm)

R2 = 0.2251ogiu(0.35/DEQ) (0.05mm < Dcq^ 0.6 mm) (5) ^ - 0.05 (0.6 mm <Dsg^ 2.0 mm)

p 0.0 { 0 % £ Fc £ 40 %) ^ 0.004Fc-0.16 (40 % < Fc^lOO %) ^

'

L = r.i k:^ {a v/(7 v') (7)

rd = 1.0 - 0.015Z (8)

39
k^- = Cti Cg-Ci ksD (9)

where Ri is the resistance based on relative density, R3 is the resistance based on

Dc.o-values, Ra is the resistance based on fine contents, N is the blow count by

standard penetration test, Ded is the mean grain size (mm), F.: is the fines content

(%), z is the depth from the actual ground surface (m), ks is the seismic

coefficient for evaluating liquefaction, Cz is the seismic zone factor, Co is the

ground condition factor, Ci is the importance factor, ko is the standard seismic

coefficient (= 0.15), a „• is the total overburden (kgf/cm'^) and o •./ is the effective

overburden pressure under static conditions (kgf/cm'^).

In the system in this study, the seismic coefficient (Ks) is assumed to be estimated

by equation (10) instead of equation (9).

where a is the maximum acceleration of the ground surface estimated by

equation (1) and g is the gravity acceleration (= 980cm/sec"^).

In this study, the liquefaction potential at the site of interest is defined with

two indices : the total thickness of liquefiable layers with the Fu-Value less than

1.0 (H/^s) and the topographical ground condition. Based on experience in past

earthquakes, the topographical ground conditions can be used as one of the

indices to roughly estimate the liquefaction potential. The topographical ground

conditions are classified into three groups as shown in Table 2 [Ref. 4] . The

liquefaction potential of a site of interest can be classified into one of three

groups as shown in Table 3.

Group-A : Site/Zone with high liquefaction potential.

Group-B : Site/Zone with low liquefaction potential.

Group-C : Site/Zone with negligible liquefaction potential.

Method to Estimate the Lateral Spread of Ground by Soil Liquefaction

The lateral ground spread (flow/movement) induced by soil liquefaction has been

investigated by the Public Works Research Institute [Refs. 5 and 6] and is being

included as one ground hazard in the seismic information system. Because the

simplified method to estimate lateral ground spread quantitatively is now under

investigation, equation (11), which has been proposed empirically in past

earthquakes, has been tentatively plugged into the pilot-system in this study [ Ref. 7] .

where D is the maximum lateral displacement of the ground surface (m), H is the

thickness of liquefied layers (m) and 6 is the maximum slope of the ground surface

or of the lower boundary of the liquefied layer (%).

Ks =a x/g (10)

D = O.TSvTH^v^e (11)

40
VISUALIZATION OF GROUND HAZARD

Information about the seismic ground motion, ground hazard and the damage of

structures should be summarized simply for the urgent and rapid inspection and

restoration of works after an earthquake disaster. Because graphically displayed

information with the use of a computer system is very understandable, the

visualization of actual and analysed information with a computer system is very

helpful for people who work on earthquake disaster remediation. In this section,

the visual information system, which has been developed as a pilot-system to

investigate the methods to display information visually over the past few years at

the Public Works Research Institute, is introduced using one case study. The

above-mentioned methods to estimate the seismic ground motion and ground hazard

are applied in the pilot-system.

Case Study Model Area for the Visual Information System

The case study model area for the visual information pilot-system is the Southern

Area of Kanto-District around Tokyo-Bay in Japan. The map of the model area can

be displayed on the computer-monitor with three kinds of scale according to

their purpose as follows ( each map is overlaid with grid lines which form

rectangular cells):

Map A : This map indicates the wide sized area (of 158 km x 130 km) with 14 x 14 = 196 cells each of which is same size as the entire Map B. Map B : This map indicates the middle sized area (of 11.3 km x 9.25 km) with 20x

20 = 400 cells each of which is same size as the entire Map C. Map C : This map indicates the narrow sized area of 566 m x 466 m scale.

It is possible to select a cell of interest in Map A and B, and to display it as Map

B and C respectively.

Example of Display in the Visual Information System

Typical examples of the display in the visual information pilot-system are shown

in Photos. 1 to 9.

The hardware for the visual information pilot-system is composed of a memory

apparatus, a display apparatus, a keyboard with a mouse, a printer and a mainframe computer with a map displayed as shown in Photo. 1. The system can be

worked with a key or a mouse by selecting the menus shown on the display or

inputting the necessary data.

The earthquake conditions, such as the epicentral location (longitude and

latitude) and Magnitude (M) (which are reported by JMA just after an earthquake

or estimated as a future earthquake), are necessary to be input as shown in Photo.

2. Furthermore, the seismic intensity reported at typical cities where JMA

offices are located can also be input.

41
The maximum acceleration and the converted seismic intensity on JMA scale can be

estimated with the use of the earthquake conditions above-mentioned by equation

(1) and can be displayed on Maps A, B and C. Photo. 3 shows the display for Map

A. Based on this visual information on the distribution of seismic ground motion,

it is possible to estimate the location and size of heavily damaged areas for rapid

and appropriate action just after an earthquake. Furthermore, it is possible to

easily understand which areas have a high potential for ground hazard problems

in future earthquakes included in the earthquake disaster prevention plan.

The data base of ground groups and topographical ground conditions

above-mentioned in equation (1) and Table 2, respectively, should be established

in advance in order to be able to estimate the seismic ground motion by equation

(1) and the total liquefaction potential defined in Table 3. Photo. 4 shows the

zoning of ground groups for each cell in Map B. The ground igroup has been

determined with the use of typical boring data for each cell based on Seismic

Design Specifications [Ref.3] . Photo. 5 also shows the zoning of topographical

ground conditions for each cell in Map B. The topographical ground condition

has been determined by the average condition of the topography at each cell.

The liquefaction potential defined in Table 3 can be displayed with three kinds of

colored grids added to the objective cell. As shown in Photo. 6, the cell of

Group-A with high liquefaction potential is displayed with a red grid and the one

of Group-B with low liquefaction potential is with a green grid. Furthermore, the

Group-C with negligible liquefaction potential is colorless. Based on these visual

information, it is possible to estimate the area with high liquefaction potential

easily and widely for both rapid and appropriate action just after an earthquake

and for future plans against earthquake disaster.

The lateral ground spread estimated by equation (11) can be displayed with

red-colored arrows for each cell as show in Photo. 7. The magnitude of ground

spread can be shown with the length of the arrow and the direction of it is shown

with the direction of the arrow. The thickness of the liquefied layer (H) at each

cell in equation (11) is determined from the results of calculations of

liquefaction resistance factor (Fu) defined by equation (2) with typical boring

data. On the other hand, the maximum slope of the ground surface (9 ) at each

cell is defined as the maximum slope between the cell of interest and the eight

cells around the cell of interest which is calculated from the average height at

the center of each cell.

The detailed location of the structures of interest can be displayed in Map C as shown in Photo. 8. The epicentral distance, ground group and total liquefaction

potential of Map C can also be displayed. When the data base of structural

conditions for each structure is introduced in advance, the conditions of

structures can be extracted from the data base and the damage conditions of

structures reported after earthquakes can also be input in Map C. The damaged

structures can be visualized to a larger scale in Map B as shown in Photo. 9. This

scale is very useful for comprehending the distribution of damaged structures.

42
FUTURE VIEW

1. Because lifeline systems are located over a large region under the ground,

seismic zoning is very effective for both seismic inspection and restoration

action just after earthquakes and for disaster prevention programs for future

earthquakes.

2. Although seismic zoning of ground motions and ground hazards has been

described in this paper, further investigation is needed to establish a simple

but rigorous method to quantitatively estimate the magnitude of liquefaction

induced lateral spread of the ground in the future.

3. Because various damage of underground structures such as lifeline facilities is

caused by various ground hazards, it is necessary to investigate the relation

between these ground hazards and the damage level of lifeline facilities in

order to create useful seismic zoning.

4. The visual information system with the use of a computer system is very useful

for people who work on earthquake disaster prevention so that they can

understand the seismic information and data rapidly and adequately.

5. For establishing the useful zoning of seismic ground hazard and induced-damage

of structures, fundamental data on the ground and structures is needed.

Estimates of the ground hazard and damage of structures should be established

in advance.

ACKNOWLEDGEMENT

The authors wish to express their sincere gratitude to Prof. T. Katayama of Tokyo

University and other members of the committee to study the visual information

system of ground hazard. The authors also wish to express their sincere gratitude

to the cooperation in constructing the pilot-system given by research engineers

of the System Division of Public Works Research Institute.

REFERENCE

1) Arakawa, T. , Kawashima, K. , Aizawa, K. and Takahashi, K., "Method to Estimate

Maximum Ground Motion and Seismic Response Spectrum (No. 3)", Technical Note of

PWRI, No. 1864, Public Works Research Institute, 1982 (in Japanese).

2) Iwasaki, T. , Kawashima, K. and Hasegawa, K.,"New Seismic Specifications for Road

Bridge in Japan", 22nd Joint Meeting, U.S. -Japan Panel on Wind and seismic

Effects, U.J.N.R., Washington, B.C., May, 1990.

3) Japan Road Association, "Part V Seismic Design of Design Specifications for

Highway Bridges", February, 1990 (in Japanese).

4) Tokida, K., Fukui, J. and Matsumoto, H. , "Simplified Procedure for Inspecting

Earthquake Resistant Potential of Highway Bridge Against Liquefaction", 23rd

Joint Meeting, U.S. -Japan Panel on Wind and seismic Effects, U.J.N.R., Tsukuba,

May, 1991.

5) Sasaki, Y., Tokida, K., Matsumoto, H. and Saya, S., "Experimental Study on

Lateral Flow of Ground Induced by Soil Liquefaction", 22nd Joint Meeting,

43
Lateral Flow of Ground Induced by Soil Liquefaction", 22nd Joint Meeting,

U.S. -Japan Panel on Wind and seismic Effects, U.J.N.R., Washington, D.C., May, 1990.

6) Sasaki, Y., Tokida, K., Matsumoto, H. and Saya, S., "Experimental Study on

Lateral flow of Ground Due to Soil Liquefaction", Second International

Conference on Recent Advances in Geoteciinical Earthquake Engineering and Soil

Dynamics, St. Louis, March, 1991.

7) Hamada, M., Yasuda, S., Isoyama, R. and Emoto, K., "Study on Liquefaction-Induced

Permanent Ground Displacement and Earthquake Damage", Proceedings of Japan

Sciety of Civil engineering. No. 376, PP.221 — 229, December, 1986 (in Japanese).

Tabic 1 Application of seismic ground motion and hazard during earthquakes.

1) Urgent and Rapid Inspection and Restoration Just After Earthquakes. — (1) Actual Distribution of Seismic Ground Motion.

Based on (2) Estimated Distribution of Seismic Ground

Motion and Hazard.

(3) Estimated Damage of Structures, Especially

Underground Structures Induced by Ground

Motion and Hazard.

2) Planning of Earthquake Disaster Prevention in Future Earthquakes.

Based on —

(1) Estimated Distribution of Seismic Ground

Motion and Hazard.

(2) Estimated Damage of Structures, Especially

Underground Structures Induced by Ground

Motion and Hazard.

44
Table 2 Relation between topographical ground

condition and liquefaction potential.

Liquefaction

Potential Geograpliical Conditions

(A) Highly Possible

to be Liquefied

Existing Channel, Existing I^iver Bed,

Old Channel, Old River Bed, Lowland between

Sand Hills, Reclamation of Old Water Surface

(Reclaimed Area of Seashore, Lal<e-shore,

Paddy Eield, etc.)

(B) Possible to be

Liquefied

Ilinter Wet Land, Natural Banl<, Sand Hill,

Sandbar, Sandy Beach, Other than the above

(A) and below (B)

(C) Not Easily to

be Liquefied

Plateau, Hill, Eand Land

Table 3 Simplified method for estimating

liquefaction potential.

Topographical

Ground

Condition

Thickness of Liquefiable Layer (m)

0 ^ Has ^ 2 2 ^ Has ^ 5 5 ^ Has ^ 20

I B A A

n C B A

m C C B

(Note) A : Site/Zone with High Liquefaction Potential

B : Site/Zone with Liquefaction Potential

C : Site/Zone with Negligible Liquefaction Potential

45
Seismic Ground Motion

Observation Data

(Acceleration etc.)

Earthquake Characteristics

(Location, Magnitude etc.)

Observed Data

In Actual EQ.

Estimated Condition

In Future EQ.

1) ATTENUATION CHARACTERISTICS

OF SEISMIC GROUND MOTION

Map

1 Ground Group i

Distribution of Seismic Ground Motion

2) SOIL LIQUEFACTION POTENTIAL

CHARACTERISTICS OF GROUND

3) LATERAL GROUND SPREAD

CHARACTERISTICS INDUCED BY

SOIL LIQUEFACTION

Information of

Seismic Hazard

of Ground In Actual EQ.

Soil Profile

Geological Condition

Above the Sea Level

Distribution of Seismic Ground Hazard

4) DAMAGE CHARACTERISTICS OF

STRUCTURES INDUCED BY

SEISMIC GROUND MOTION AND

HAZARD

Information of

Damage of

Structures In Actual EQ.

Structural Condition

of Structures (Lifeline Facilities etc.)

Occurrence/Distribution of Damage of

(Underground) Structures

Seismic Zoning NOTE:

Urgent Inspection and

Speedy Restoration of

Earthquake Hazard

In Actual Earthquakes

Planning of Earthquake

Disaster Prevention

in Future Earthquakes

Information from the

Site In Earthquake

I Data Base Prepared |

Establlsliment of

Estimation Method

Fig. 1 Flow of information related to seismic ground motion/hazard

and induced-damage of structures.

46
Photo. 1 External appearance of visual Information pilot-system.

Photo. 2 Input of earthquake location (longitude and latitude), RichterScale Magnitude and Seismic Intensity reported by JMA.

47
Photo. 3 Display of maximum ground surface acceleration and Seismic

Intensity estimated in Map A (Southern-Area of Kanto-District

: 158km X 130km, 196 cells).

Photo. 4 Display of Map B on the ground groups estimated

from actual ground data to estimate maximum ground

surface acceleration.

48
Photo. 5 Display of Map B on the topographical ground conditions

to estimate liquefaction potential.

Photo. 6 Display of Map B on the liquefaction potential estimated

for each cell (Group-A : Red grid added, Group-B: Green

grid added, Group-C : Not colored grid).

49
Photo. 7 Display of Map B of the magnitude and direction

of maximum lateral spread of ground for each cell.

Photo. 8 Display of Map C of the location of structures

and liquefaction potential.

50
Photo. 9 Display of Map B on the location of damaged

structures reported from sites.

51

II. SEISMIC DESIGN AND ANALYSIS:

TRANSPORTATION

"Seismic Risk Identification and Prioritization

in the CALTRANS Seismic Retrofit Program"

B. Maroney. J. Gates

"An Old Bridge Gets a Seismic Facelift"

G.M. Snyder, C.E. Lindvall, R.P. Lyons

"Seismic Inspection and Seismic Strengthening

of Highway Bridges in Japan"

K. Kawashima, S. Unjoh, H. lida

"Recent Advances in Seismic Design and Retrofit

of California Bridges"

J.E. Roberts

53

SEISMIC RISK IDENTIFICATION & , PRIORITIZATION

IN THE CALTRANS SEISMIC RETROFIT

PROGRAM

BRIAN MARONEY^ & JAMES GATES"

^Senior Bridge Engineer, Seismic and Structural Analysis

California Department of Transportation, Sacramento, California.

"Supervising Bridge Engineer, Seismic and Structural Analysis

California Department of Transportation, Sacramento, California.

ABSTRACT

The procedure used by the California Department of Transportation

in the State's Seismic Retrofit Program to identify and prioritize

the bridges most vulnerable to collapse due to large earthquakes is

presented in this paper. A risk analysis is developed in which

expert judgements replace a typically large statistical database.

The result is a risk analysis based on expert knowledge gained from

past earthquakes and bridge characteristics which can be applied

quickly to a decision making process. Brief comments on project

classification and projected project dates are included for

completeness. Proposed future objectives and modifications to the

procedure are discussed.

55
INTRODUCTION

The 1971 San Fernando earthquake exposed a number of deficiencies

in the bridge design specifications of that time. The bridge

design specifications were modified to correct the deficiencies and

a seismic retrofit program was started to address the various

deficiencies of the structures in place. The initial objective of

the seismic retrofit program was to insure continuity at all of the

bridge superstructure joints to prevent drop-type failures. Using

55 million dollars of state funds approximately 1,300 bridges were

retrofitted. Typical methods used were to add restraining cables

or rods at piers and hinges and shear keys at abutments and

bearings. In 1987, shortly after the Whittier earthquake, 64

million dollars of state funds were made available for additional

retrofitting. These funds were to be directed toward the retrofit

of structures with single column bents, as they were perceived to

be less redundant and therefore at higher risk. This effort was

underway when the Bay Area of California was rocked by the Loma

Prieta earthquake on October 17, 1989.

CALTRANS has received specific direction in response to the Loma

Prieta Earthquake. Following the Loma Prieta Earthquake, Senate

Bill No. 36 {1} was passed which appropriated 80 million dollars

immediately, and potentially a significantly greater amount for

future seismic retrofit projects. This bill identified Caltrans as

the lead agency for inspection and retrofit if necessary for all

publically (i.e., local and state) owned bridges throughout the

state, except for those bridges not on the state highway system in

the counties of Los Angeles and Santa Clara, in which cases the

respective counties are designated as the lead agencies. The

Governor's Board of Inquiry on the 1989 Loma Prieta Earthquake {2}

stated in a list of recommended actions, specific goals of

this policy shall be that all transportation structures be

seismically safe and that important transportation structures

maintain their function after earthquakes." With this direction

and funding, CALTRANS has been charged with the task of providing

safety to the travelling public through necessary retrofit

modifications to any transportation structures which may not be

adequate during a large earthquake.

CALTRANS is responding to these directions. Figure 1 illustrates

the strategy adopted within the Division of Structures to identify

and prioritize, group into projects, and submit to design bridge

structures to be retrofitted.

There are some 23,000 (approximately 11,000 state and 12,000 city

or county) bridges in the state of California (see Figure 2) that

CALTRANS is responsible for in some capacity threatened by over 200

faults (see Figure 3) . It was and still is economically

unrealistic to suggest every structure be immediately retrofitted

to withstand large magnitude earthquakes without some damage. A

retrofit philosophy was adopted at the start of the seismic

retrofit program which offers reasonable direction.

56
It is CALTRANS philosophy to first retrofit those structures which

are at greatest risk and are the most vital. The ultimate goal is

to see that all of the bridges in the state are capable of

surviving large earthquakes. Some damage is inevitable but

collapse is believed to be preventable with proper retrofitting.

The exception to this is in the case of lifeline structures. If

undue stress or hardship may be place on a community due to a structure being temporarily out of service the structure should be

made to withstand even the maximum level earthquake and remain in

service

IDENTIFICATION & PRIORITIZATION

Identification of bridges likely to sustain damage during an

earthquake is an essential first step in a retrofit program. What

can be classified as a level one risk analysis was employed as the

framework of the process which led eventually to a consensus list

of prioritized bridges.

A conventional risk analysis determines a probability of failure or

survival. This probability is derived from a relationship between

the load and resistance sides of design equations. Not only is an

approximate value for the absolute risk determined, but relative

risks can be obtained by comparing determined risks of a number of

structures. Such analyses generally require vast collections of

data to defined statistical distributions for all or at least the

most important elements of some form of analysis, design, and/or

decision equations. The acquisition of this information can be

extremely costly if obtainable at all. Basically, what is

typically done is to execute an analysis, evaluate both sides of

the relevant design equation, and define and evaluate a failure or

survival function. All of the calculations are carried out taking

into account the statistical distribution of every variable

throughout the entire procedure.

To avoid such a large questionable investment in resources and to

obtain result which could be applied quickly as part of the seismic

retrofit program, an alternative was recognized and developed.

What can be called a level one risk analysis procedure was used.

A similar risk evaluation to identify and prioritize bridges for

retrofitting was used in the single column retrofit program {3}.

The difference between a conventional and level one risk analysis

is that in a level one risk analysis expert judgements take the

place of data supported statistical distributions.

The level one risk analysis procedure employed can be summarized in

the following steps:

1) Survey the available expert database to identify and weight

high risk structural and transportation characteristics,

2) Define preweight scoring schemes.

57
3) Calculate bedrock accelerations at all bridge sites,

4) Identify high risk soil sites which possess the capacity to

liquify or substantially amplify bedrock accelerations, and

5) Prioritize bridges by summing weighted bridge structural and

transportation characteristics.

Step 1 was performed by surveying experts in the fields of bridge

design, maintenance, and construction; and geotechnical and

geological sciences. Typically, bridge structural and

transportation characteristics with high correlations to past

earthquake bridge damage would be used to identify variable

components of a risk evaluation. Due to the absence of a substantial database of maximum credible California earthquakes and

their effects on California bridge structures and transportation

systems, an alternative database was identified and tapped. Expert

judgements by professionals in the field of bridge engineering were

used to derive and calibrate a risk algorithm. The survey requested

which characteristics would have high correlations to bridge damage

or cost to public transportation and what their relative

correlations would be. This panel of experts represented hundreds

of years of bridge experience. The result of this step is

illustrated in Figure 4

.

Preweight scoring schemes were developed in step 2. These were

developed using engineering judgement considering what data were

available, their form, and engineering/mechanical relationships

between the particular characteristic and typical structural or

transportation system responses. Each preweight score is a number

between 0.0 and 1.0. A number close to 0.0 reflects a relatively

low risk and a number close to 1.0 reflects a relatively high risk.

A typical preweight scoring scheme is presented in Figure 5.

Step 3 was carried out by consulting the California Division of

Mines and Geology. A team of seismologists and engineers identified

seismic faults believed to be the sources of future significant

events. Selection criteria included location, geologic age, time of

last displacement (late quarternary and younger) , and length of

fault (10 km minimum) . Each fault was evaluated for style, length,

dip, and area of rupture surface in order to estimate potential

earthquake magnitude. Fault locations were digitized. An

appropriate attenuation model was developed by Mualchin of the

California Division of Mines and Geology to be used throughout the

state. It is a weighted average of several published models.

These two efforts combined to produce a method for determining the

maximum credible peak bedrock acceleration at the site of each

state and locally owned bridge in California. This is achieved by

attenuating maximum credible bedrock accelerations from the closest

fault to the bridge site. This is greatly simplified with Map Sheet

#45 by Mualchin of the California Division of Mines and Geology

{4} . This map is effectively a map of maximum credible peak bedrock

58
accelerations throughout the state of California.

Top CALTRANS engineering geologists from throughout California

collaborated to complete step 4 . A knowledge base constructed by

years of studying and working with the geologic strata of

California was thus made available to the Division of Structures.

The team of engineering geologists, working with 26 geologic maps,

identified high risk soil sites which possess the potential to

liquify and/or substantially amplify bedrock accelerations. The

identified high risk soil sites were then digitized for computer

use

Step 4 is the process of combining the previous efforts via a logical, dependable, and repeatable algorithm which can be

computerized. This was performed with a graphical interface system

by ULTIMAP at CALTRANS. A final single risk number for each

structure was calculated by summing the products of risk algorithm

weights and each structure's preweight scores, producing a numerical measure of relative risk between 0.0 and 1.0. An example

calculation is included in the appendix of this paper. An indepth

description of each component and each preweight scoring scheme is

presented in another paper by Maroney {5}. Figure 6. illustrated

the distributed of assigned risk numbers to state and local

bridges

DATA COLLECTION

Acquisition of the bridge structural and transportation data was a formidable task. The CALTRANS Structures Maintenance database was

relied upon heavily. The database is a federally mandated library

of records which describe a variety of structural, transportation,

and economic bridge data. However, any single source of information

cannot be relied upon alone. Parallel information seeking efforts

were initiated to gather the best available information on all

state and locally owned bridges. These additional efforts include

a solicited Seismic Retrofit Inventory (SRI) survey of locally

owned bridges and a state wide General Plan (GP) review of all

bridges, and a collection of special knowledge on selected

structures which engineers state wide are identifying as

threatened

The SRI forms requested local agencies to field survey their

structures and return to CALTRANS data which would assist in

evaluating their potential need for retrofit. An SRI form is

included in the appendix of this paper. All fifty-eight counties

and over 300 cities have completed approximately 12,000 SRI forms

in 18 months. Approximately 100 forms are outstanding and 700 forms

have been received that do not match any existing records at the

writing of this paper. CALTRANS processed, corrected if necessary,

and entered the returned form's information into a database. This

information is serving as a vital element in the retrofit program.

The GP review utilized engineers examining the general plan for

59
every structure CALTRANS has plans for in its archives. The goals

of this effort were twofold. The first was to remove all structural

types from the retrofit program which have proven to be not

susceptible to catastrophic failure due to earthquakes. These

kinds of structures include: modern bridges designed since 1980

without outrigging knee joints, flat slab, timber, single-span

monolithic, typical two-span monolithic, and well-seated singlespan bridges. This effort reduced the number of bridges which

required a more detailed review or analysis. The second reason for

the GP review was to serve as a check for bridge identification and

database quality. This proved valuable in cases in which bridge

structures had been replaced, renamed, or renumbered. Included in

the appendix are the GP seismic review data sheet and the detailed

seismic review data sheet. It should be noted that the data sheets

were modified as new conditions were encountered which suggested

modification. Approximately 9000 state and 4000 locally owned

bridge GPs have been reviewed. Over 2000 detailed seismic reviews

have been performed.

Special knowledge pertaining to bridge structures throughout the

state has proven valuable. The Division of Structures maintains an

open door policy for engineers and professionals to contribute to

the effort in identifying high risk structures through special

knowledge of structures or site characteristics which they have

gained through professional experience with a bridge or site in the

state of California.

In order to respect previously committed time schedules, the bridge

plan review effort has two levels of review. They are the GP

review discussed earlier and a detailed seismic review which is

providing an opportunity to remove a large number of bridges from

the retrofit program by investigating the structural plans and

details. Such details would include support widths, column

reinforcement, footing reinforcement, bearing type, etc.... The

detailed review will also allow reviewers to take advantage of

additional knowledge gained from recent retrofit structural

analyses. This review is taking place before and following the

assignment of the risk values.

It is recognized that certain structures on the state

transportation system can be identified as having unusually high

levels of risk associated with them. Examples include: structures

with rigid outrigger bents, structures with leased airspace below,

structures spanning faults, and structures on routes which can be

categorized as lifeline arteries. These structures are being

identified by numerous methods and will be appropriately analyzed,

and if necessary retrofitted.

PROJECT CLASSIFICATION

Identified bridges are being grouped into projects. The total

inventory of bridges is separated first into three groups

respecting the three lead agency jurisdictions and then further by

60
the results of the GP review effort. Respective lists were provided

to the state, and Santa Clara and Los Angeles counties with seismic

risk factors associated with all bridges. Methods employed to

oversee the retrofitting of the bridge structures at the project

level in the counties is the responsibility of the respective lead

agencies. Each of the bridge structures which fall under CALTRANS

jurisdiction not eliminated by the GP review will be assigned a seismic risk factor. The risk factors will be used to prioritize

the bridges

,

Project grouping considers ownership, number of bridges, estimated

costs, and geographic locations. All bridges in any single project

are owned by the same city or county. The maximum number of bridges

in any one project is 20. (It is estimated that 50% of these will

usually be eliminated in a detailed final screening. Maximum

estimated costs per project do not exceed $4 million. Reasonable

geographic limitations are used to group bridge sites into

projects

Each project is prioritized. Projects are assigned a Seismic

Project Priority Number (SPPN) . The SPPN is the average of each

bridge; s risk factor in a project weighted by each respective

bridge's estimated retrofit construction cost. It is estimated

that project prioritization will be completed in 1991.

FUTURE OBJECTIVES

The seismic retrofit program is currently underway and is based in

part on an identification and prioritization program which employed

the best available resources of the time and good engineering

judgement. These resources can be improved and the results

enhanced through data collection and relatively simple research.

Some of the areas targeted for refinement include:

1) improvement of the dataset,

2) hazard mapping,

3) documentation of structural sensitivity by class,

4) identification of lifeline refinement,

5) calibration procedure refinement,

6) transformation of risk model from additive model to

multiplicative model,

7) higher level risk analysis, and

8) sensitivity study of model weights.

Any decisions or judgements made based on data are dependent on the

61
quality and quantity of the supporting data. Though the dataset

available to CALTRANS is large it can and should be enriched.

Fault data will be enhanced by the processing of data which will

facilitate the assignment of additional fault characteristics such

as mechanism, depth, orientation, projection, and probable

frequency content and return periods. With a more comprehensive

fault dataset Caltrans will be poised to develop, evaluate, and

thereby consider probability of seismic events if necessary. With

such data organized, maps illustrating maximum credible and

probable event responses are a natural by-product.

Processing and refinement of soil data will be a high priority.

CALTRANS maintains boring logs and driving records for nearly every

state bridge. These logs contain information which could be used

to predict soil and structure response to an earthquake. This data

is not presently accessible by automated means. However, an effort

is underway to facilitate electronic access to such date.

Structural data could be enhanced by including superstructure seat

widths and locations, design accelerations and Z factors, column

heights and/or stiffness variations, etc... Transportation data

could be enhanced by including local input to identify lifeline

corridors which must be kept open in the event of a major

earthquake (e.g., a bridge on the sole route leading to a community

hospital)

.

The present risk model was calibrated from the response of a survey

sent to qualified experts. Though this surveyed was an effective

and efficient method of calibration, some iterative and personal

interaction would certainly improve the calibration scheme. A

conference is planned to provide technical interaction through

sharing of ideas and perspectives toward refinement of the risk

model calibration.

The risk model is to be transformed from an additive to a

multiplicative model. That is, from the form of

n i?=5^ [ {weighty) {pie-weightscoze^)]

to the form of

m n i?=JJ [{macioweight^) (J^ {microweightj) ipre-weightscorOj) ) j^] 2=1 j=l

This will allow structures which have high risk structural and

transportation characteristics to be excused more easily (i.e., via

automation) from the retrofit program if their seismic hazard is

low. It should be noted this will also required very precise fault

62
information

Higher level risk analyses could be implemented. The present

analysis produces a measure of relative risk. If resources are made

available, future analysis could produce measures of absolute risk

or probabilities of damage or impact to the state or local

communities

Judgements made in risk evaluation will be investigated through a sensitivity study. The algorithm component weights will be varied

and the variation in the resulting distribution will be analyzed.

There exists an infinite number of combinations for the weighting

scheme. It is anticipated that structures built before 1980 will be

evaluated respecting only hazard, then respecting only structural

characteristics, and then only transportation characteristics.

SUMMARY

Past earthquakes have exposed potentially threatening deficiencies

in California bridges. CALTRANS recognized this situation as early

as 1971 and immediately initiated a retrofit program. However,

modest state funding of the program limited its scope to high

potential areas. The Loma Prieta Earthquake brought attention to

the program. And with legislation, and recommendations from the

Governor's board of inquiry, CALTRANS is being directed to

accelerate the seismic retrofit program. Important initial steps to

the strengthened program are to identify and prioritize bridge

structures which possess a probability of server damage in a maximum credible earthquake. This is currently underway at CALTRANS

using what can be termed a level one risk analysis. The risk

analysis employs an expert knowledgebase and good engineering

judgement to produce a prioritized list of bridges which will be

grouped into projects and released for design and construction. The

risk analysis program is an ongoing effort to identify potentially

catastrophic and functional failures in the California

transportation system. As additional and more accurate

incorporated, the program's evaluations will mature in accuracy and

precision.

63
FIGURES

i

64
SEISMIC RETROFIT PROJECT FLOWCHART

STPUCTLFS'S

AJKHIVES

SEJSUIC RETROFIT

INYENTCPY rOFIUS

TYPED INTO DATABASl AAO INVESTlOATED

-a-£CX UAINTENANCE-

-CP'S

-TEL£. TO rim.D

UAINTENAKS

DATABASE

GP

ULTIUAP FOR

PRIORITIZATION

PART or LIST

IS E1.IU1NATED

RALPH SOMARIYA

I) GROLP INTO PROJECTS

H3 OnjDBK 90KS OUT wnnajr cam

USCKim AT ZTM aF

erTAJLa

Mm tuiamTtD.

orTAZua njH mvaat. yam rmjcrums

CARRCCL HARRIS

1) OPOLP INTO PROJECTS

ZJ PRIORITIZE

PROJECTS

MO BKtoaK text CUT LOOKOm AT ZTM m

OUT TO BRIDGE DESIGN

AHJ^Cn CONSULTANT

OUT TO BRIDGE DESIGN

AJ^CyCR CONSULTANT

Figure 1. Program Flowchart

65
PHASE II RETROFIT

Figure 2, State of California Bridges

66
PHASE II RETROFIT
SK ALGORITHM

R = ^[(wt )*(pre-wt )]

ABUT TYPE

DETOUR , ncy^

RTE TYPE (5.0%^ - ^

FAC X-ED (6.0%)

SKEW (7.0%)

HEIGHT (7.0%)

(8.0%)

EXPOSURE (10.0%)-^

SINGLE COL

(13.0%) YEAR CONST

(12.0%) ACCEL

(12.0%) SOIL

(11.0%) HINGES

Figure 4. Prioritization Weights

68
Figure 5. Example Preweight Function

69
I

Histogram of Bridge Seismic Risk Values

state & Local

600

Risk Value

Figure 6. Prioritized Bridge Distribution

70
FUTURE RISK ALGORITHM

Figure 7. Probable Form of Future Risk Algorithm

71
APPENDIX

72
RISK ALGORITHM EXAMPLE ^^^^ ' °^ ^

RISK RATING EXAMPLE:

GIVEN : 80 ft 80 ft

21 ft

SfiSsJasi end diaphram

abutment

single column bent

YEAR DESIGNED

-- PEAK BEDROCK ACCELERATION

HIGH RISK SOIL SITE

# OF HINGES

-- COLUMNS /BENT

-- ADT ON BRIDGE

f --HEIGHT - LENGTH

" SKEW

- FACILITY CROSSED

I - ROUTE TYPE

" DETOUR LENGTH

! ~ ABUTMENT TYPE

I,

I

i

I

i

1955

0.45g

not in a high risk soil zone

0

1

veh

20,000 day

21 ft (SRI form calls out 20 - 30 ft)

160 ft

15 degrees

U.S. route

county route

10 miles

end-diaphragm
RISK RATING EXAMPLE: continued page 2 of 2

COMPONENT

YEAR DESIGNED

PEAK BEDROCK ACCEL

HIGH RISK SOIL SITE

0.1 3* (1-0)

0.12* (4^)

- # OF HINGES

-- COLUMN/BENT

- TRAFFIC EXPOSURE

HEIGHT

- SKEW

FACILITIES X-ED

ROUTE TYPE

DETOUR LENGTH

- ABUTMENT TYPE

7g

0.12 *(0)

0.11 *(0)

0.10* (1.0)

0.08 * (20000

^* "^60 ft = 3.2* 10^ ==> 0.0317)

see TRAFFIC EXPOSURE PREWEIGHT CURVE

0.07 * (0.995)

if height available use HEIGHT PREWEIGHT CURVE

if height not available use length to estimate height

In this case SRI form is the best available data,

and an average for the 20-30 ft range is used.

0.07 * (0.025)

see SKEW PREWEIGHT CURVE

0.06 * (0.8)

U.S. route crossed

0.05 * (0.5)

county route on bridge

0.05* (0.1)

see DETOUR PREWEIGHT CURVE

0.04 * (0)

monolithic

0.13

0.077

0.0

0.0

0.1

0.0025

0.07

0.0018

0.048

0.025

0.005

0.0

RISK RATING ==> X= ^-^^

74
RISK ALGORITHM

YEAR CONSTRUCTED

PEAK ROCK ACC.

SOIL AT SITE

# OF HINGES

COLUMNS PER BENT

TRAFFIC EXPOSURE

(length & ADT on deck)

HEIGHT (length)

SKEW

FACILITY CROSSED

ROUTE TYPE

(on structure)

LENGTH OF DETOUR

ABUT. TYPE

0.13 * (0.0 -> yr >71; 0.5 -> yr<=45; 1.0-->45<yr<=71)

0.1 2 * (MCE acc, normalized to 0.7g)

0.1 2 * (0.0 --> low risk site; 1 .0 --> high risk site)

0.1 1

* (0.0 --> 0; 0.5 --> 1 ; 1.0 -> 2 or more)

0.10 * (0.5 --> multi-col; 1 --> single col)

0.08 * (neg. parabola, normalized to 2*10^ ADT*LENGTH))

0.07 * ((LOCAL) neg. cubic, normalized to 30)

((STATE) 0.0 -> 0-300; 0.5 -> 300-600; 1.0 -> >600)

0.07 * (pos. parabola, normalized to 90)

0.06 * (same as RTE TYPE, STREAM = 0.8)

0.05 * (INTERSTATE ~> 1.0;

U.S. ROUTE ~> 0.8; STATE ROUTE -> 0.8;

RAILROAD ~> 0.7;

FED. FUNDED CO. ROUTE OR CITY ST. -> 0.5;

NON-FED. FUNDED CO. ROUTE OR CITY ST. -> 0.2;

FED LAND, STATE LAND, & UNDEFINED ~> 0.0)

0.05 * (linear, normalized to 100)

0.04 * (0-0 --> monolithic; 1.0 --> nonmonolithic)

THE SUM OF THESE WILL BE BETWEEN 0.0 AND 1 .0

all preweights are between 0.0 and 1 .0

75

AN OLD BRIDGE GETS A SEISMIC FACELIFT

Gary M. Snyder, M. ASCE, Chief Engineer of the Metropolitan Water

District of Southern California, Los Angeles

C. Eric Lindvall, President of Lindvall, Richter & Associates, Los Angeles.

Robert P. Lyons, M. ASCE, Senior Engineer with the Metropolitan Water

District of Southern California, Los Angeles.

ABSTRACT

Elastomeric bearings are used to retrofit 28 supports for a 50-year-old 1010-foot

(308 m) long bridge and pipe. The structure is an essential part of The Metropolitan

Water District's feeder system to the Southern California area. Use of the bearings

insures that the structure will behave elastically and safely during the controlling

maximum expectable event, a magnitude 7.0 earthquake originating on the

San Jacinto fault 11 miles (18 km) distant. The bearings were economical and easily

installed with minimal shut down time.

77
INTRODUCTION

The Santa Ana bridge carries the Upper Feeder pipeline, which here is a 116 in. (259 cm) inside-diameter steel cylinder. The 1,010 ft. (308 M) bridge consists of two

types of structures, one being three, 180 ft. (55 m) long steel trusses, and the other, a

series of concrete piers on 50 ft. (15.3 m) centers with the pipe spanning between

them (See Figs. 1 and 2).

The pipeline is part of the 700 miles (1130 kms) of distribution pipeline used by the

Metropolitan Water District of Southern California (MWD) to import water from the

Colorado River and northern California. MWD feeds over 2 million acre-feet

(2.5 billion cu. meters) of water a year to almost half of southern California's 15 million

people.

Immediately following the area's 1971 earthquake in San Fernando, MWD began

intensively examining its system to identify segments that might not survive a major

earthquake. The bridge was found to be one such segment.

A pseudo-static analysis indicated that the bridge's trusses and pipe-support

pedestals, as well as some individual truss members and connections, could be highly

overstressed during a major earthquake. So MWD hired Lindvall, Richter & Associates

(LRA) to do a more detailed seismic stability analysis.

ISOLATION BEARINGS

As a result of LRA's analysis, the bridge has been retrofitted with isolation bearings at

all truss piers and pipe piers (See Figs. 3, 5, and 6). The bearings are rectangular

blocks of natural, ozone-resistant rubber with cylindrical cores of pure lead. Inside

each bearing, closely spaced horizontal sheet steel lamination (shims), bonded to the

rubber during fabrication (vulcanization by heat), provide vertical stiffness to the

bearing by inhibiting side bulging (See Fig. 3).

Under small lateral loads and movements, the lead provides most of the lateral

stiffness and behaves elastically. However, under sufficiently large loads the lead

yields, and the bearings' lateral stiffness is then provided by the rubber alone. At the

Santa Ana River Crossing, the bearings were sized so the lateral force on each

bearing is about 1 5% of the vertical load when the pipe is full of water. This lateral

force is about twice the maximum windload the pipe will experience. The lead core begins to yield when the bearing has displaced 5/8 in. (16 mm) laterally.

78
This thinking led to bearings from 12 in. to 20 in. (305 mm to 508 mm) square in plan,

and from 9 to 11 1/2 in. (229 mm to 292 mm) high. Their lead cores have diameters

from 4 1/2 to 7 in. (114 mm to 178 mm)

Lateral properties of the bearings came from design guidelines and test data supplied

by bearing supplier Dynamic Isolation Systems, Inc., of Berkeley, Calif.

COMPUTER MODEL

The Santa Ana bridge and its isolation bearings were modelled by feeding truss and

beam elements into the SAPV program developed at the University of California,

Berkeley, and modified at the University of Southern California, Los Angeles, and the

ADENA program developed at MIT.

The program performed linear and nonlinear analyses, respectively. In the latter, the

bearings were modelled as kinematic hardening bilinear truss elements in the

horizontal directions, as linear truss elements in the vertical.

The mathematical model representing the bridge and motions it will undergo is highly

sophisticated. Each member of the three trusses was represented explicitly, and

where stability or secondary bending effects were important, the pieces of each

member were modelled individually.

The pipe skin was represented in the mathematical model as a cylindrical Vierendeel

truss. The water was represented by assuming the Vierendeel truss was internally

supported by a beam running down the pipe axis, with radial spokes at the terminus

of each finite element in the model.

Shear and flexural behavior of the pipe were represented by modifying the Vierendeel

truss skin to eliminate the effects of the axial area of the longitudinal elements. Inertia

and shear properties in the plane of these skin elements were selected to match the

theoretically calculated bending and distortion behavior of the steel pipe. Longitudinal

properties were represented entirely by the centralized axial beams. The expansion

joint in the pipe near the bridge's mid-span was modelled by deleting one of the

centralized axial beams.

LOADING CONDITIONS

The bridge was analyzed for gravity, earthquake, thermal, hydraulic and wind loads.

Because of the inertial effects of water in the pipe and the proximity of major faults,

wind loads are subordinate to the earthquake loads. Hydraulic loads, from a 464 ft. head, produce a hoop tension on the pipe equal to 49% of yield.

79
The thermal load conditions give rise to rather complex behavior. The pipe is fixed

along its axis at the two bridge abutments; an expansion joint makes the pipe

discontinuous near bridge midspan. Further, each truss is fixed along its axis to one

of its supporting piers. To take gravity loads, the pipe is supported by rocker

supports along the bridge trusses. Lateral stability of the pipe is assured by hinged

ties affixed to the trusses. Spaced at 36 ft. (1 1 m) on center, these vertical and lateral

supports permit differential thermal longitudinal motion of pipe and truss.

Seismicity at the bridge is dominated by the San Andreas and San Jacinto faults

(See Fig. 4). The former is capable of producing the greater magnitude event, but the

latter is closer, 11 miles (17.7 km) away vs. 17 (27.4 km). That, and the fact that the

more recent significant seismic activity has been along it, makes the San Jacinto Fault

dominant.

A maximum expectable earthquake on the San Jacinto fault was defined as a Richter

magnitude 7.0 event. For this event the peak ground acceleration at the bridge is 0.35 g, and the duration of strong ground shaking is about 20 sec. To respond

satisfactorily, the supporting bearings must maintain a stability factor of safety of at least two.

A maximum credible event on the San Jacinto fault would have a Richter magnitude of

7.5. This event would produce a peak ground acceleration of 0.40 g at the bridge,

with a strong shaking duration of 30 sec. For this event the bridge and pipe structure

was permitted to sustain some damage, but it must remain in service with no risk of

collapse.

Ground motions were constructed on the computer to represent both maximum

credible events. These motions were synthesized from the records obtained during

the 1952 earthquake in Kern County, Calif., at the Taft Lincoln School. The modified

records have response spectra that compare well with those from the 1971 San

Fernando and 1979 Imperial Valley earthquakes. Three uncorrelated components, two

horizontal and one vertical, were constructed to represent both the maximum

expectable and maximum credible events.

DYNAMIC ANALYSIS

The ADENA program was used to analyze the bridge-pipeline's behavior with and

without the new bearings. A step-by-step Newmark integration procedure was

deployed, with constant average accelerations in each 0.02 sec time-step interval.

Energy dissipation was introduced into the model by using mass proportional

damping. The proportionality constant for the damping matrix was selected so that

modal damping close to 5% of critical was realized throughout the linearalized period

range of interest.

This damping value of 5% is appropriate for most steel structures subject to strong

ground shaking.

80
The maximum expectable earthquake produced a wholly satisfactory response in the

bridge and pipe. Only the elastomeric bearings experienced yielding, and by doing so

they limited the extreme lateral force experienced by the bridge to less than 20% of its weight. In contrast, for the pre-retrofit condition, the potential lateral force was equal

to the structure's full weight, which could have resulted in significant failures or even

collapse of the bridge.

Two factors gave rise to the structure's much improved seismic response. The use of

soft, yielding lateral supports shifted the fundamental period of the structure from

about 0.6 sec to about 1.0-1.5 sec. This in turn reduced accelerations and lateral

forces felt by the bridge and pipeline. Secondly, and more important, the bearings

increased the rate of energy dissipation to a value equal to that for a 40% damped

oscillator.

The earthquake lateral force felt by the structure was reduced 80%, and extreme

displacements were modestly reduced. Most of the displacements were in the

bearings themselves, with the supported bridge and pipe moving together much as a

single lobe over its 1,010 f. (308 m) length. The extreme lateral displacement was 4.3

in. (109 mm).

RETROFIT STOPS

After completing the installation of the elastomeric bearings at the trusses, the first phase of construction, the trusses were monitored for longitudinal movement due to

thermal expansion and contraction. The initial assumption that the trusses would

thermally expand and contract longitudinally in place proved to be incorrect. Due to

horizontal forces imposed on the bearings from the pipe rocker supports, which

canted when the warm steel pipe was filled with cold water and contracted, the

bearings distorted and moved the south truss north 2-1/2" over several days.

Because of the location of the pipe expansion joint (See Fig. 2), the north and center

trusses moved south 1" and 1-1/2" respectively in the same time frame. The

movement of the trusses was stopped by welding temporary shear plates to the top

and bottom bearing plates of both bearings at one end of each truss.

Returning the trusses to their original positions was accomplished by removing the

temporary shear plates and installing sandwiched plates, that could be locked using

high strength friction bolts, on all of the truss bearings. The trusses were "walked"

back to their original positions by alternately locking and unlocking the plates in the

early morning and late afternoon to take advantage of the warm days and cold nights.

When the trusses returned to their original positions, one end of each truss was

locked.

81
A permanent stop consisting of a beam spanning along the widtin of tine concrete pier,

between the elastomeric bearings, with a hinged center support was installed on the

north end of the north and center trusses and the south end of the south truss (See

Fig. 7). The ends of the beam were welded to the top bearing plates. The hinged

support at the center of the beam was anchor bolted to the concrete pier.

Longitudinal distortion of the bearings due to rocker-induced loads is restrained, yet

lateral distortion of the bearings during a seismic event will be uninhibited.

The second phase of construction consisted of replacing the rigid pedestal supports

with elastomeric bearings at the pipe piers. It was decided to design stops to limit the

longitudinal distortion of the elastomeric bearings supporting the pipe (See Fig. 8) at

the piers due to rocker-induced loads caused by thermal expansion and contraction of

the pipe. Like the stops installed on the trusses, these stops will limit longitudinal

bearing distortion, yet permit lateral distortion of the bearings during a major

earthquake.

CONCLUSION

The use of elastomeric bearings in lieu of rigid pedestals to support the Santa Ana

River Crossing has increased the period of the structure and the rate of energy

dissipation. Consequently, the design earthquake lateral forces will be reduced to

20% of what the structure would have experienced prior to modification. Use of these

bearings, in combination with stops that prevent creep and rocker induced loads from

distorting the new bearings longitudinally, has mitigated the risk of significant damage

to the Santa Ana River Crossing, due to a major earthquake, while permitting the

structure to function as originally designed.

POSSIBLE FUTURE RESEARCH

Since the Santa Ana River Crossing is seismically instrumented, the ground,

Pier No. 8, and the truss acceleration, velocity, and displacement will be known after a major earthquake. This data could be used to compare the actual response of the

structure with design predicted response.

82
AERIAL VIEW OF SANTA ANA RIVER CROSSING

FIGURE 1

83
84
ELASTOMERIC BEARING - SCHEMATIC VIEW

^ CUT AWAY SHOWING THICK

OUTER STEEL SHIMS AND

THIN INNER STEEL SHIMS

FIGURE 3

85
86
RETROFIT ELASTOMERIC BEARING - FIGURE 6

87
TRUSS RETROFIT STOP - FIGURE 7

PIPE SUPPORT BEARING AND BEARING STOP - FIGURE

88
REFERENCES

Bathe, K. J., Wilson, E. L, and Pederson, F. D., "SAPIV, A Structural

Analysis Program for Static and Dynamic Response of Linear Systems,"

Earthquake Engineering Research Center, University of California,

Berkeley, 1974 - since modified as "SAPV," University of Southern

California, 1978.

Buckle, Ian G., and Mayes, Ronald L., Personnel Communication

regarding elastomeric bearings.

Computech Engineering Services, Inc., letter report dated September 6,

1985.

Computech Engineering Service, Inc., letter report dated October 10,

1985.

Dynamic Isolation Systems, Inc., "Seismic Base Isolation Using LeadRubber Bearings," Berkeley, California, 1983, and revised January, 1984.

Lindvall, Richter & Associates, Draft, Phase Hi Seismic Stability Analysis,

1010' Santa Ana River Crossing of the Upper Feeder with Elastomeric

Bearings, November 1985.

Schnabel, P. H., and Seed, H. B., 1973, Acceleration in Rock for

Earthquakes in the Western United States: Seismological Society of

America Bulletin, v. 63.

89

SEISMIC INSPECTION AND SEISMIC STRENGTHENING

OF HIGHWAY BRIDGES IN JAPAN

BY

Kazuhiko KAWASHIMA"

Shigeki UNJOH^

and

Hiroyukl IIDA^

1) Head, Earthquake Engineering Division, Public Works Research

Institute, Ministry of Construction, Tsukuba Science City,

Ibaraki-ken, Japan

2) Research Engineer, ditto

3) Assistant Research Engineer, ditto

ABSTRACT

This paper presents a state of practice of seismic inspection and seismic

strengthening of highway bridges in Japan. Description is firstly given to the

history of seismic inspection and seismic strengthening of highway bridges in

Japan. An inspection method of existing highway bridges based on a statistical

analysis of past seismic damage is presented. Practical seismic strengthening

methods for vulnerable highway bridges are described. Finally, current

research efforts for developing seismic inspection and seismic strengthening

methods of reinforced concrete bridge piers with termination of main

reinforcement at mid-height are presented.

91
INTRODUCTION

Highways in Japan consist of Expressways (3,721 km), National Highways (46,661

km), Prefectural Roads (128,202 km), and Municipal Roads (925,138 km). Along the

highways and roads, excluding the Municipal Roads, there are about 60,000

bridges with span lengths (deck length between two adjacent substructures) of

15 m or longer.

Although the number of bridges constructed per year depends on the year and

span length, it is about 6,000 for concrete bridges and 2,000 for steel bridges

with a length of 15 m or longer.

Located along the Pacific Seismic Belt, Japan is one of the most seismically

disastrous countries in the world and has often suffered significant damage

from large earthquakes. Fig. 1 shows the largest magnitude of the earthquakes

which occurred in the past'\ It is recognized that the earthquakes with

magnitude over 8 have occurred with rather short recurrent period in and

around Japan in the past. It should be noted that seisraicity is especially high

along the Pacific coast. Cities large in population and industrial products such

as Tokyo, Osaka and Nagoya are located in this region.

Table 1 shows the highway bridges which suffered damage in the past

earthquakes since the Kanto Earthquake of 1923. It should be noted that

although there were many bridges which suffered damage due to earthquakes,

the number of bridges which fell down was only 15.

Fig. 1 Largest Magnitude of Earthquakes in the Past

92
Based on surveys of the damaged bridges, it is pointed out that the three major

factors which contributed to the damage of bridges are^' :

a) weakness of substructures

b) weakness of bearing supports, and

c) weakness of surrounding subsoils.

From such factors, the following types of damages were most often developed in

the past:

a) substructure : tilting, settlement, sliding, cracks, and overturning

b) superstructure : movement, buckling and cracks near the supports, and

falling of girder

c) bearing supports : failure of supports, and pull-out or rupture of

anchor bolts

Although these kinds of damage are the ones commonly observed in the past

earthquakes, the damage t3T)es have been changing as shown in Table 2 in

accordance with the progress of seismic design methods and improvements in

construction practice^^

Table 1 Damage of Highway Bridges in the Past since Kanto Earthquake of 1923

DATE EARTHQUAKE MAGNITUDE NUMBER OF BRIDGES DAMAGED

NUMBER OF BRIDGES WHICH

FELL DOWN

1923. 9. 1 KANTO 7.9 1.785 6

1946.12.21 NANKAI 8.1 346 1

1948. 6.Z8 FUKUl 7.3 243 4

1949.12.26 IMAICHI 6.4 1 0

1952. 3. 4 TOKACHI-GKI 8.1 128 0

1962. 4.30 MIYAGI-KEN-HOKUBU 6.5 187 0

1964. 6.16 NIIGATA 7.5 98 3

1968. 2.21 EBING 6.1 10 0

1968. 5.16 TOKACHI-OKi 7.9 101 0

1978. 1.14 IZU-OHSHIMA 7.0 7 0

1978. 6.12 MIYAGI-KEN-OKI 7.4 95 1

1982. 3.21 URAKAWA-OKI 7.1 5 0

1983. 5.26 NIHON-KAI-CHUBU 7.7 176 0

1984. 9.14 NAGANO-KEN-SEIBU 6.8 14 0

TOTAL 3.191 15

93
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94
This paper presents pre-earthquake measures for mitigating earthquake hazards

of highway bridges in Japan. Development of seismic inspection and seismic

strengthening methods for existing highway bridges are presented.

HISTORY OF SEISMIC INSPECTION AND SEISMIC STRENGTHENING

OF HIGHWAY BRIDGES IN JAPAN

The nationwide seismic inspection of highway bridges with span length longer

than 15 m was made in 1971, 1976. 1979 and 1986 by the Ministry of Construction.

Overcrossings in city area are also included in "bridges". Table 3 shows the

inspected items of the past seismic inspections of highway bridges. The first

inspection in 1971 and second inspection in 1976 were to detect deteriorated

highway bridges susceptible to falllng-off of superstructures during

earthquakes. The third and fourth seismic inspection in 1979 and 1986 was to

clarify structural resistance of highway bridges against falling-off of

superstructures during destructive earthquakes.

Table 3 Inspection Items Considered in the Past Seismic Inspection of

Highway Bridges in Japcin

Year Inspection Items

1971 • Deterioration

• Bearing Seat Length S for Bridges supported by Bent Piles

1976 Deterioration of Substructures. Bearing Supports and Girders/Slabs

• Bearing Seat Length S and Devices for Preventing Falling-off of Superstructure

1979 • Deterioration of Substructures and Bearing Supports

• Devices for Preventing Falling-off of Superstructure

Effect of Soil Liquefaction

• Bearing Capacity of Soils and Piles, and Strength of RC Piers

• Vulnerable Foundations fBent Piles and RC Frame on Two Independent Caisson Foundation)

1986 • Deterioration of Substructures, Bearing Supports and Concrete Girders

• Devices for Preventing Falling-off of Superstructure

• Effect of Soil Liquefaction

• Strength of RC Piers fBottom of Piers and Termination Zone of Main Reinforcement)

• Bearing Capacity of Piles

• Vulnerable Foundations (Bent Piles and RC Frame on Two Independent Caisson Foundation)

Note) Deterioration includes cracks of concrete members, excessive inclination, slip and subsidence of foundations, and scouring of surrounding soils of foundation.

95
For those bridges which were judged vulnerable to destructive damages during

earthquakes, seismic strengthening works have been made. Table 4 shows the

number of highway bridges inspected and the budget spent for the seismic

strengthening works. For those bridges consisting of several spans for

crossing rivers and valleys, a whole group of bridges is counted as "a bridge"

in Table 4. Therefore actual number of bridges is much larger than the number

presented in Table 4. Because bridges inspected in the past also require the

latest inspection, the number of bridges inspected and strengthened includes

duplication. In the latest 1986 inspection, about 40,000 bridges were inspected

and about 11,700 bridges were found to require seismic strengthening. Most of

the bridges require installation of the device for preventing superstructure

from falling-off from the substructures as shown in Fig. 2'^'

. In the past four

seismic strengthening programs by 1989 fiscal year, 23,466 bridges were

strengthened. As of 1989, about 300 billion Yen was spent for the seismic

strengthening works including bridges.

Table 4 Number of Highway Bridges Inspected by the Past Seismic Inspection

in Japan^' ^

Year Inspected

Require

Strengthening

Strengthened

1971 17,970 3,200 1.441

1976 24,504 7,110 2,742

1979 34,712 16,011 13,580

1986 40,370 11,764 5,703

Fig. 2 Devices for Preventing Superstructure from Falling

96
VULNERABILITY INSPECTION OF HIGHWAY BRIDGES

Seismic inspection methods to detect highway bridges vulnerable to earthquakes

have been developed and amended several times to reflect progress of bridge

earthquake engineering and lessons learned from the past seismic damage. The

most important requirement for the inspection method was to be able to assess the vulnerability of a number of highway bridges at site without complex

calculations. The latest seismic inspection method"' which was referenced in the

1986 seismic inspection was formulated on the statistical analyses of 124

bridges damaged in the past earthquakes'^^

.

In the statistical analyses, factors which are likely to affect the seismic

vulnerability of highway bridges were firstly studied with use of the Type II quantification analysis. The rank of damage degree was classified into high

vulnerability (Rank A), moderate vulnerability (Rank B) and low vulnerability

(Rank C) as shown in Table 5. From the analysis of the past seismic damage, 15

items, as shown in Table 6, were selected as the factors likely to affect seismic

vulnerability. The 15 items consists of four principal factors, i.e., intensity of

earthquake ground motions, properties of superstructure and substructures,

devices for preventing falling-off of superstructure from substructures, and

ground condition. Each item was further divided into several categories.

Table 5 Definition of Seismic Vulnerability

Rank Vulnerability ol Seismic Damage Rank of Damage Degree

Rank A —

High Vulnerability

Possibility for suffering damage

or damage degree is high

5 Falling-off of Superstructure or 4 Extensive Damage

Rank B —

Moderate Vulnerability

Possibility for suffering damage

or damage degree is moderate

3 Moderate Damage

Rank C —

Low Vulnerability

Possibility for suffering damage

or damage degree is low

2 Slight Damage or

1 Minor Damage or 0 No Damage

Predicted damage rank y; was assumed to have a form of

yi = 2 2 5 i jk • xjK ^ (1)

J k

in which xjk represents a weighting factor for the k-th category of the j-th

item, and d rjk represents a variable corresponding to the category k in the

item j of the i-th bridge. The variable 5 ijk was so defined that it takes a value of 1 if the characteristics of the i-th bridge correspond to the category

k in the item j, and is 0 otherwise. The weighting factor Xjk was determined so

as to minimize the sum of square of the difference between the predicted damage

rank and the actual damage rank.

97
Table 6 Items and Categories which Affect Seismic Vulnerability of Highway

Bridges

Hem Category

Seismic Damage Rank Results of Statistical Analysis

0 No Damage

1 Minor Damage2 Slight Damage3 Moderate Damage

4 Extensive Damage

5 FallingOil ol 5 up6rstructure

Normalized Score Range

Partial Correlation

Coellicient

^Intensity ol Peak Ground

Acceleration ama. |cm/sec^)

1

( 5%) 1 ( 5%) 0.169

1 219 0.343

200sama< <3(X) lo \ Do /o

)

*; / AO'*/ \ 0 ( 1<! /o) Ju [ DJ /of 8 ( 40%) 1 1 r J /o) — 0 283

SOO^arnax <400 5 ( 26%) 5 ( 42%) 18 ( 33%) 10 ( 50%) 6 ( 75%) 4 ( 40%) 0.176 400£ama <500 2 ( 17%) 1 ( 2%) 1 ( 5%) 1

( 13%) 2 ( 20%) 0 936

500 § ama. 4 ( 40%) 0,616

©Design

Speciiicalions

lyiib or i9oy 1 ( 5%) 6 { 11%) 6 { 30%) 5 ( 63%) 7 ( 70%) 0.517

lyjD or 1^04 17 ( 89%) 6 ( 50%) 41 ( 75%) 1 1 ( 55%) 3 ( 38%) 3 ( 30%) -0 223 0 740 0.319

1Q71 nw 1QQn ly/i or lyou 1

( 5%) 6( 50%) 8 (15%) 3 ( 15%) 0.284

©Type ol Superstructure

Gerber or Simply Supported

Girder (2 or More Spans)

12 ( 63%) 7( 68%) 40 ( 73%) 17 ( 85%) 8 (100%) 10 (100%) 0.081

0.390

- - -

0 161 One- span Simply Supported

Girder, or Countinuous Girder

with 2 spans or More

5( 26%) 3 ( 23%) 1 1 ( 20%) 2 ( 10%) -0 232

Arch. Frame. One-span Continuous Girder. Cable-stayed

Bridge. Suspension Bridge

? r 1 1 % 1 ? r 17%1 4 / 7%1 1 ( 5%) — 0 308

©Shape ol Superstructure

Skewed or Curved 3( 16%) 1 ( 8%) 4 ( . 7%) -0.396

0 424 0.122

Straight 16 ( 84%) 11 ( 92%) 51 ( 93%) 20 (100%) 8(100%) 10(100%) 0 027

©Materials ol Superstructure

RC or PC 7 ( 37%) 5 ( 42%) 22 ( 40%) 7 ( 35%) 1 ( 13%)

7 ( 88%)

6 ( 60%) -0,141

0.233 0.131

Steel 12 ( 63%) 7 ( 58%) 33 ( 60%) 13 ( 65%) 4 ( 40%) 0 092

©Slope in BrirJge Axis 6% or Steeper 1

( 2%) 1( 13%) 1( 10%) 0 919

0.941 0. 161 Less than 6% 19 (100%) 12 (100%) 54 ( 98%) 20 (100%) 7 ( 88%) 9 ( 90%) -0.023

©Device to Prevent Fallingoil ol Superstructure

None 1

( 5%) 1{ 8%) 20 ( 36%) 8 ( 40%) 6 ( 75%) 10 (100%) 0,459

One Device 16 ( 83%) 6( 50%) 28 ( 51%) 11 ( 55%) 2 ( 25%) -0 181 1.106 0 358

Two Devices or More 2( 11%) 5 ( 42%) 7 ( 13%) 1

( 5%) -0.647

©Type ol Substructure

Single-line Bent Pile 1( 5%) 5( 9%) 2 ( 10%) 3 ( 30%) 0 292

Reinlorced Concrete Frame 1( 5%) 1( 8%) 9( 16%) 8 ( 40%) 4 ( 50%) 4 ( 40%) 0.259 0.411 0.178

Others 17 ( 89%) 11 ( 92%) 41 ( 75%) 10 ( 50%) 4 ( 50%) 3 ( 30%) -0,119

©Height ol P^er H

10m sH 4( 21%) 5 ( 42%) 12 ( 22%) 8 ( 40%) 2 ( 25%) 3 ( 30%) 0 172 5ms H<10m 7 ( 37%) 3 ( 25%) 29 ( 53%) 7 ( 35%) 6 ( 75%) 5 ( 50%) -0.038 0.284 0.125 H<5m 8 ( 42%) 4 ( 33%) 14 ( 25%) 5 ( 25%) 2 ( 20%) -0 112

©Ground

Condition

Extremely Soil in Group 4 1 ( 5%) 1

( 5%) 2 ( 25%) 0,523

0.983 0 273

Group 4 5 ( 26%) 2( 4%) 1 1 ( 35%)

6 ( 30%)

4 ( 50%) 7 ( 70%) 0 224

Group 3 3( 16%) 8 ( 67%) 33 ( 60%) 1

( 13%) 3 ( 30%) 0 040

Group 2 1( 5%) 1 ( 8%) 8 ( 15%) 1 ( 5%) 0.112

Group 1 9 ( 47%,) 3 ( 23%) 12 ( 22%) 1 ( 5%) 1

( 13%) -0.461

©Irregularity ol Supporting Ground

Irregular 1 ( 8%) 1

( 2%) 4( 20%) 1

( 13%) 0.307

0.420 0.104

Almost Unilorm 19 (100%) 11 ( 92%) 54 ( 98%) 16 ( 80%) 7 ( 88%) 10 (100%) -0.024

©Ellecl ol Soil Liquelaction

Liqueliabie 4 ( 7%) 2( 10%) 2 ( 25%) 6 ( 60%) 0 724 0.816 0.255

Non-liqueliable 19 (100%) 12 (100%) 51 ( 93%) 18 ( 90%) 6 ( 75%) 4 ( 40%) -0.092

©Ellect ol Scouring

Recognized 1 ( 5%) 0.312

0.315 0.033 None 19 (100%) 12 (100%) 55 (100%.) 19 ( 95%) 8 (100%) 10 (100%) -0.003

©Materials ol Substructure

Plane Concrete in Accordance

with 1926 Specs, or 1939

specs.

1 ( 5%) 2 ( 20%) 0.995

1.020 0.167

RC. PC, Steel or Unreinlorced Concrete in Accordance with Specs, in 1956 or Later 19(100%) 12(100%) 55 (100%) 19 ( 95%) 8 (100%) 8 ( 80%) -0.025

©Type ol Substructure

Timber, Brick. Masonry.

Other Old Unknown Materials 1( 8%) 1( 2%) 1 ( 5%) 1 ( 13%) 4 ( 40%) 0.383

0.697 0.171 RC Piles. Pedestal Piles or

Pier Supported by Two

Independent Caissons 2( 11%) 1 ( 8%) 9( 16%) 4 ( 20%) 2 ( 25%) 2 ( 20%) -0.314

Foundations Designed by Specs, in 1971 or Later 17 ( 89%) 10 ( 83%) 45 ( 82%) 15 ( 75%) 5 ( 63%) 4 ( 40%) 0.034

98
From the weighting factors presented in Table 6, the effects of each item were

found as shown in Table 7. The following considerations were subsequently

included in the statistical analysis to formulate an inspection method.

a) Because the objectives of the inspection method are to assess the seismic

vulnerability of highway bridges subjected to ground shalting of JMA Intensity

V or larger (peak ground acceleration larger than 0.25 g), the Intensity of Peak

Ground Acceleration amax is dropped from the evaluation item assuming that

amax is larger than 0.25 g.

b) Evaluation of the strength of reinforced concrete piers at the

mid-height where main reinforcement is terminated was introduced.

c) Because collapse, such as falling-off of superstructure, generally

occurred because of excessive relative movements between the superstructure

and the substructures, and failure of substructures due to inadequate

strength, the evaluation of the seismic vulnerability for both the relative

movement and for the strength of substructures should be made.

d) Even if there are some unsatisfactory conditions in the evaluation, final

evaluation may not consider them to be critical if the remaining factors are in

good evaluation. Consequently, it was decided that those bridges with at least

one "critical" or "safe" condition are to be considered to have either high or

low seismic vulnerability. Below are some examples of evaluation of such

specific types of structure :

• Those designed in accordance with the 1980 Specifications shall be

classified into Rank C (safe) unless appreciable deterioration is

detected.

• Those constructed by timber, brick, masonry, or old unknown materials

shall be classified into Rank A (vulnerable).

• Those supported by single-line bent piles foundation which are

constructed on loose alluvial sandy layer vulnerable to liquefaction or

very loose clayey deposits shall be classified into Rank A (vulnerable).

• Single-span simply supported girder bridges with the span length less

than 15 m shall be classified into Rank C (safe).

The procedure of seismic inspection and an inspection sheet are shown in Fig. 3

and Table 8, respectively^' The evaluation of the seismic vulnerability is

made in accordance with the points which reflect the vulnerability to excessive

relative movement between superstructure and substructures (point X), and the

strength of substructures (point Y) as shown in Table 9.

99
Table 7 Factors which Affect Seismic Vulnerability of Highway Bridges

Items Seismic Vulnerability © Design Specifications Tfiose designed in accordance with 1926 or 1939 Specifications have

higher vulnerability © Type of Superstructure • Gerber or simply supported girders with 2 or more spans have

higher vulnerability • Arch. Irame, continuous girders, cable-stayed bridges or suspension bridges have lower vulnerability © Sliape of Superstructure Skewed or curved bridges do not necessarily have higher

vulnerability than straight bridges © Pflaterisis of Superstructure Reinforced concrete bridges or preslressed concrete bridges have

lower vulnerability than steel bridges although the difference is small © Slope in Bridge Axis Bridges with slope in bridge axis have higher vulnerability ® Device lor Preventing Falling-off

of Superstructure

Bridges with devices lor preventing lalling-oll of superstructure have

lower vulnerability © Type of Substructure Bridges supported by single-line bent piles or by reinforced concrete frame placed on two separate caisson loundations have higher

vulnerability © Height of Piers Bridges supported by higher piers have higher vulnerability © Ground Condition Bridges constructed on solt soil have higher vulnerability @ Effect of Soil Liquelaction Bridges constructed on sandy soil layers susceptible to liquelaction have higher vulnerability @ Irregularity of Supporting Soil Condition Bridges constructed on soils with irregularity ol supporting

conditions have higher vulnerability @ Effect of Scouring Bridges where the surlace soils are scoured have higher

vulnerability

(n) Materials of Substructures Bridges supported by plane-concrete substructures designed in accordance with 1926 or 1939 specifications have higher

vulnerability @ Type of Foundation Bridges supported by timber, brick, masonry or other old unknown

type substructures have higher vulnerability ® Intensity of Ground Motion Bridges subjected to higher intensity of ground acceleration have

higher vulnerability. In particular, vulnerability becomes quite high when the bridges are subjected to peak ground acceleration larger than 400 gal |0.4g|

100
( Slort )

Designed by 1980^

Yes ^-^Specificatiors 7

'Wooden, Mason ry ^Yes

or Brick Moteriol' <

, One-row Bent Pile Substructures, Embede^on^ yp<; very Soft Soils including ">-i^

Soilj^ith Higti LiquefoctCTi ^fttentioL?--^

.One-Span Bridq?with, ^pon Large of I5m_ ^^or less?-

Rank-A

Superstructure |

Number of Devices to Prevent Oislodgement

Yes

Pa = I

2 or more^

No]

Inspection Item

(A), Pa

I Substructure!

^CoTitinuolis-^ No

-RC Column-^ No

'iles?..

Circular Cross-Section

''or Rectangular wilh"^^No

Section Ratio ~~^of l/4or less'

_Soft Soils (including. Liquefaction

Potential

Substructures such fOne-Row Bent Pile's^ 2 Coissons, or RCXfomes rigid

.Substructures with^ Scour Deterioration

or Permanent Deformation?-^

-~^Yes

Yes

-\Yes

--\Yes

Inspection Item

(8), Pb

Inspection Item (D),Pd

X = Pa X Pb

Y = Pc X Pq

Fig. 3 Procedure of Seismic Inspection for Highway Bridges

101
Table 8 Inspection Sheet for Seismic Vulnerability of Highway Bridges

Point o( Inspection Foctors ol Inspection Evaluation © Design Specilicalions

4.0: 1926 Specs 2:0: 1956 Specs. 1.0: 1971 Specs,

or i?j3 opecs. or luo^ opecs. or laou opecs.

Inspection

l^ormat (A) (D Superstructure Type

3.0: Gerber Girder or 1.5: Simply-supported 1.0: Arch. Flame, ConSimply-supported Girder or Continuous tinuous Girder (One

Girders with Two Girders Consisting ol Span), Cable-stayed Spans or More T«(o Spans or More Bridge. Suspension

Bridge

Inspection lor Deformation ol (5) Stiape ol Superstnjclure 1.2: Skewed or Curved Bridge 1:0: Straight Bridge

Superstructure ® Materials ol Superstructure 12:RcorPC 1 0: Steel

Inspection lor @ Gradient 1 2: 6% or Steeper 1 .0: Less Than 6%

Vulnerability

to Develop Excessive

Oelormation

(6) Falling-oil Prevention Device 2 0: None 1 0: One Device

Pa = ®x@x(Dx®x(Dx(6) Pa=

(7) Type ol Substructure 2 0: Single-line Bent Pile Foundation 1.0: Others

(8) Height ol Pier H 2.0:Ha10m 1.5: 5sH<10m 1.0: H<5m

Inspection

t^ormat [a) (D Ground Condition 5 0: Extremely Solt 2.5: Group 4 2.0: Group 3 -12: Group 2

in Group 4 1.0: Group 1

Inspection tor Deformation ol Substructure ® Ellects ol Liquelaclion 2 0: Liqueliable 1.0: Non-liqueliable @ Supporting Ground Condition 1.2: Irregular 1.0: Almost Uniform @ Scouring 15: Recognized 1.0: None

PB = @x(Dx(Dx@x(n)x@ Pb= @ Shear Span Ratio (h/D) 20:1<h/D<4 1.0:h/D24 0.5:h/Ds1

Inspection

rUMIIdl [K^f @ Tension Cracks In Flexure at Terminated Point ol Main

Reinlorcemenl

2.0: Cracks Wil Occur 1 .0: Cracks Will Possibly 0.3: Cracks wilt Not Occur Occur

Inspection lor Strength ol RC Pier at Termination ol

® Safety Factor lor Yield Strength at Teiminaled Seclion

ol Mam Reinlorce- menl

(HJ) Sin aoSmgl.l 2.0: 1.1<Si„<1.5 0.5:Sina1.5 CT52) Smn 30 Smngl.l 2 0: 1.1<SmT,Sl.3 1.0: 1.3<Smn<1.5

• 0.5: Se1.5

Reinlorcemenl ® Shear Stress a (tl/m') 3 0: 0245 2 0:30s<;<45 1.0: 15s<j<30 0.5:ff<15

Inspection lor Vulnerability

to Develop

Failure Due

to Inadequate

Pc = @x(R)x<3535 xCllJ)"® Pc = @ Failure ol Fixed Supports and

Proximity

5.0: Extensive Failure 2.0: Small Failure 1.0: None ® Extraordinary Damage ol Pier 5.0: Extensive Damage 2.0: Small Damage 1.0: None

Strengtfi ol Substructure

Inspection Formal (D)

Inspection lor Strenglli ol

® Materials ol Substruclure

2 0 Plane Concrete Older Than 1926 Excluding 1.0: Others

Gravity-type Abutment @ Construction method ol Foundation

2 0 Timer Pile. Masonry, 1.5: RC Piles. Pedestal 1.0: Foundation Designed

RrirL nthor CiiH Piloc Pior QiinnnrtoH hu 1Q71 QnDrc snrl DMLK, Ulllcl vlu riles, riei oUppUllCU Uy lijf I OpcCb. dllU Construction Methods by Two Independent Other Later Specs. Caissons

Substructure ® Foundation Type

1.5: RC Flame Supported by Two 1.0: Others Independent Caisson Foundations @ Extraordinary Failure ol Foundation

2 0: Recognized 1.0: None

Po = ®x(iDx@x(g)x@x@ Po =

Evaluation of Delormation and Strengtti X = PaxP8= and y = PcxPo=

Table 9 Evaluation of Seismic Vulnerability

Rank of Seismic

Vulnerability

Evaluation Points

X

Y

Pc = 1.0 PC 7^1.0 A—Vulnerable XS60 YglOO

B—Moderate 20 g X < 60 5gY<10 50gY<100

C—Sale X<20 Y<5 Y<50

Note) Gut ol two ranks obtaintJ Irom X-point and Y-point. higher rank (A is the highest) should be taken as the linal ranking ol the bridge inspected. For

obtaining evaluation points X and Y. reler to Table 8.

102
SEISMIC STRENGTHENING OF HIGHWAY BRIDGES

Table 10 shows the feasibility of seismic strengthening against the 16 factors

which would affect the seismic vulnerability of highway bridges (refer to Table

7). Among the 16 factors, ® Devices for Preventing Falling-off of the

Superstructure, (D Type of Substructure, ® Effect of Soil Liquefaction, ®

Effect of Scouring, ® Materials of Substructures, ® Types of Foundation, and

® Effect of Termination of Main Reinforcement at Mid-height are the factors for

which countermeasures for strengthening the bridge are feasible.

Countermeasures against for the remaining 9 factors can not be made unless the

whole bridge be replaced.

Table 10 Feasibility of Seismic Strengthening for 16 Factors which Affect

Seismic Vulnerability of Highway Bridges

items

Feasibility of Seismic Strengthening

Principles of Countermeasures O Design Specifications X

© Type of Superstructure X

© Shape of Superstructure X

© iVIaterials of Superstructure X

© Slope in Bridge Axis X

© Device for Preventing Falling-off

of Superstructure o Installation of Devices © Type of Substructure o Strengthening of Substructures © Height of Piers X

© Ground Condition X

® Effect of Soil Liquefaction o

Strengthening of Fundations or Strengthening of Surrounding Soils @ Irregularity of Supporting Soil Condition X

@ Effect of Scouring o

Treatment for Prevention of Scouring, or Strengthening of Foundations @ IVIaterials of Substructures o Strengthening of Substructures @ Type of Foundation o Strengthening of Foundations @ Intensity of Ground Motion X

® Effect of Termination of r/lain Reinforcement at Mid-height o Strengthening of Substructures

Note O Items for which seismic strengthening is feasible X Items for which seismic strengthening is not feasible

103
Fig. 4 shows how the countermeasures can be made for the above described 7

factors. Installation of devices for preventing falling-off of superstructure,

strengthening of foundations, and strengthening of piers and abutments are the

main measures of seismic strengthening.

Seismic

Retrofit

Installation of Falling-off Prevention Devices

Strengttiening of Foundation

Strengthening of Substructures

© Devices for Preventing

Falling-off of Superstructure

@ Effect of Soil Liquefaction ® Effect of Scouring

® Type of Foundation

- © Type of Substructures

- @ Materials of Substructures

'— ® Effect of Termination of Main Reinforcement at Mid-height

Connection between Superstructure and

Substructures

Stopper

Extension of Seat Length

Replacement of Soil

Enlargement of Footing

Increase of Number of Piles

Installation of Lateral Beams

Concrete Covering of Ground Surface

Steel Plates/Piles for Guarding

Foundation

Placing of New Concrete Surrounding

Old section

Steel Jacket

Placing of Wall

Increase of Number of Piles

Fig. 4 Selection of Seismic Strengthening Measures for Highway Bridges

Figs. 5, 6 and 7 show the methods for selecting the installation of the stoppers

at movable supports, falling-off prevention devices, and elongation of seat

length Se and bearing seat length S as measures of seismic strengthening for

existing bridges. The methods are based on a number of practices in the past'^'

.

Figs. 8 and 9 show measures for strengthening foundations and strengthening

substructures for existing bridges, respectively.

The seismic inspection and strengthening methods of transportation facilities

including highway bridges were compiled and published from the Japan Road

Association in the form of the "Guide Specifications for Earthquake Hazard

Mitigation for Transportation Facilities - Pre-Earthquake Countermeasures

in 1987'^'

.

104
105
106
Chipping-^

Anchor Bor (SD 30)

Injection of Resin

Concrete Brock

7777777777777,

Anchor Bolt

Resin Bonding

•Steel Bracket

Fig. 7 Elongation of Seat Length Se and Bearing Seat Length S for Existing

Highway Bridges

107
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— , .Cl-^ Zl^UJZD

UJ ^ O

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Z.^ Q <I h;zzt3 O =5— Z

cc I— «5 H-U-— UJ

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be

108
EXAMPLE OF SEISMIC STRENGTHENING

Fig. 10 shows an example of seismic strengthening of reinforced concrete frame

supporting a bridge, constructed in 1968, on the Tomei Expressway of Japan

Highway Public Corporation"-"'". The frame was strengthened so that the

seismic safety be ensured against the Tokai Earthquake which is anticipated to

occur with the magnitude over 8 in the Tokai area. The piers were strengthened

by placing new reinforced concrete with thickness of 17 cm. Reinforcing bars

were anchored into the footing. They were bent at the base of piers with

anchorage length of 112 cm (35 times the diameter of reinforcing bars) being

provided to prevent pulling-out from the footing. Photo 1 shows the completion

of the strengthening work.

Photo 1 Seismic Strengthening of RC Frame by Placing New Reinforced Concrete

Fig. 11 shows an example of seismic strengthening of foundation constructed in

1952. To increase bearing capacity of the foundation, number of piles was

increased by enlarging the foundation'^'.

Fig. 12 shows an example of seismic strengthening of bent piles which was

constructed in 1959. Because bent pile has small stiffness to inertia force in

longitudinal direction, it was judged vulnerable. A unique strengthening

method was adopted in this bridge'^\ Instead of strengthening each bent pile,

only two abutments at both ends of the deck were strengthened by constructing

new cast-in-place concrete piles, and the top of the bent piles was tied to a

steel beam which was newly placed on both sides of the deck.

109
110
Ill
112
RESEARCH FOR DEVELOPING SEISMIC STRENGTHENING METHODS

Various research efforts have been paid to develop rational seismic inspection

and strengthening method. Because current efforts are being concentrated to

develop an inspection and strengthening method of reinforced concrete piers

with termination of main reinforcement at mid-height, research progress for the

termination zone is introduced.

The importance for this type of damage became apparent when a bridge was

critically damaged during the Urakawa-oki Earthquake in 1982'^'. The Shizunai

bridge which is of five-span continuous girders and reinforced concrete piers

suffered destructive damage at the piers as shown in Photo 2.

Significant shear failure was found at mid-height of reinforced concrete piers,

where some of main reinforcement were terminated. Photo 3 shows the similar

damage during the 1978 Miyagi-ken-oki Earthquake'^'. Although the damage was

not so serious as the Shizunai Bridge, it was found that this type of failure

occurred widely in the past earthquakes. Because wall type piers were commonly

constructed in the past, shear failure developed by the inadequate anchorage

length of main reinforcement did not become so pronounced in the past. Single

columns with smaller concrete sectional area are likely to be adopted in recent

years, and it is considered important to investigate failure mechanism of this

type of damage for developing seismic inspection and strengthening method.
i

Photo 3 Damage of Sendai Bridge during Miyagi-ken-oki Earthquake in 1978

Before the Design Specifications of Highway Bridges was revised in 1980,

anchorage length of main reinforcement terminated at tension zone was only 20

- 30 times a diameter of reinforcing bars. It was increased in 1980 to effective

width of the piers plus 20 times the diameter or the termination has to be made

upper than the point where the stress of the reinforcing bar becomes half of

the allowable stress.

For investigating failure mechanism, a series of loading test were made at the

Public Works Research Institute as shown in Photos 4 and 5^^\ Fig. 13 shows a method proposed based on the tests at PWRI for identifying the vulnerability at

the termination zone. The inspection is made by two parameters, i.e., failure

mode factor Sv and safety factor at termination zone r y , which are defined as

Sv = FvVFv^ (2)

Fy"^ = My^/M"^ (3)

Fy^ = My^/M^ (4)

where

Sy : failure mode factor

Fy^, Fy^ : safety factor representing strength of pier in terms of

bending moment at termination point and base, respectively

M"^, : bending moment developed at termination point and base,

respectively, when pier is subjected to a lateral inertia force

during earthquakes (tf m)

My^, My^ : yielding bending moment at termination point and base,

respectively (tf m)

114
Photo 4 Loading Tests of RC Pier with Termination of Main Reinforcement

at Mid-Height (Square Section)

Photo 5 Loading Tests of RC Pier with Termination of Main Reinforcement

at Mid-Height (Circular Hollow Section)

115
START

Yes Seismic Strengthening

END

Fig. 13 Seismic Inspection for Reinforced Concrete Piers with Termination of

Main Reinforcement at Mid-Height

In Eqs. (2) and (3), the failure mode factor Sv is used to identify where failure

is likely developed firstly at either termination zone or base, and safety

factor Fv^ represents redundancy to failure at the termination zone. With use

of Sy and Fy^, the decision is made in accordance with Table 11 by following a flow chart as shown in Fig. 13. Check of shear stress is also made as shown in

Fig. 13.

Fig. 14 shows the effectiveness to identify where the failure was developed by

means of the failure mode factors Sy. Failure is likely to be developed at the

termination zone when Sy ^ 0.9, while, flexural failure at the base tends to be

developed when Sy is larger than or equal to 1.1 as shown in Table 11.

Fig. 15 shows how the safety factor Fy^ is effective to assess the damage

degree. The damage degree is defined as the failure which is possibly developed

at the loading stage of 5 times the yielding displacement {5 5 y). From Fig. 15, it

is clear that significant failure including rupture of main reinforcements tends

to be developed when Fy^ < 1.2.

116
Table 11 Estimation of Seismic Vulnerability on the Strength of Termination

Zone by Failure Mode Factor Sy and Safety Factor Fy^

(a) Estimation of Failure Mode

Failure Mode Factor Sy Failure Mode

Sy^l.l Flexural Failure at Base Sy< 1.1 Vulnerable to Failure at Termination Zone

(b) Estimation of Damage Degree (In Case of Sy < 1.1)

Safety Factor Fy

Damage Degree at Termination Zone

at the Loading Displacement of 5(5y

Fy<1.2

Rupture and Serious Buckling of Main

Reinforcement

Fy^1.2

Diagonal Cracks. Spalling-off of Cover

Concrete. Slight Buckling of Main

Reinforcement

FAILURE MODE

Failure was developed ot termination zone.

Although slight damage was

developed at termination zone,

final failure was developed

at base.

Failure was developed

at base

Shizunai Bridge

(P3Pier)

j

I

^^^Shin-Eai Bridge P3 Pier

I lA

LEGEND

Square

Section

Circular Section Wall Type The numbers represent shear span ratios of specimens.

0.5 j.O

Failure Mode Factor Sy

Fig. 14 Estimation of Failure Mode by Sy

1.5

117
DAMAGE DEGREE AT TERMINATION ZONE

Rupture of Moin Reinforcement

Serious

Slight

Buckling of Main Reinforcement

Spolling-off of Cover Concrete

Cracks

No Damage

Over 30cm

0~30cm

Almost

Significant Moderate

O

LEGEND

A 5.4"

9.9

. Square

Section 5.6. O 4.9

Circulor Section + 7.) Wall Type The numbers represent shear span ratios of specimens.

^ 4-

Shizunoi Bridge (P3 Pier)

Serious Damoge

-Shin-Eai Bridge (P3 Pier)

A

0.4 0.6 0.8 1.0 1.2

Sofety Foctor Fy

1.4 1.6

Fig. 15 Relation between Safety Factor Fy^ and Damage Degree at the Loading

Displacement of 5 5 o

Seismic strengthening methods for the termination zone are being developed at

various organizations""'"^''. There are several possible ways for strengthening

the termination zone. One is to place new reinforced concrete section around

the existing section. However, in this method, increase of the mass of the pier

for requires additional increase of the foundation, and noise and air pollution

during tipping of cover concrete make it difficult to be adopted in urban area. To avoid such difficulties strengthening by means of a steel jacket wrapped

around the existing pier seems promising. Another wrapping by means of carbon

fiber is also being studied'^'.

A series of dynamic loading tests of specimens strengthened by a steel jacket

are being made at the Public Works Research Institute jointly with the

Metropolitan Expressway Public Corporation and Hanshin Expressway Public

Corporation Parameters considered in the tests are length and thickness

of steel jacket, and injection material between steel jacket and concrete.

Tests are being made for circular, square and wall type piers.

According to the past tests, steel jackets were effective to strengthen piers

vulnerable to shear failure at the termination zone. The minimum length of the

steel jacket may be 1.5 to 2.0 times the pier width D. Epoxy resin seems better

than concrete mortar as an injection material, because separation of steel

jacket from concrete surface is more restricted.

Based on the test results, about 20 piers each were strengthened at the

Metropolitan Expressway Public Corporation'^^ and Hanshin Expressway Public

Corporation Figs. 16 and 17, and Photos 6 and 7 show seismic strengthening

of reinforced concrete piers. The piers were covered fully from the top to the

bottom by steel jackets with thickness of 6 mm and epoxy resin was used

injected.

118
Photo 6 Seismic Strengthening of RC Piers on Metropolitan Expressway

by Steel Jackets

Photo 7 Seismic Strengthening of RC Piers on Hanshin Expressway

ji by Steel Jackets

119
120

CONCLUDING REMARKS

Because seismic design for highway bridges was initiated in 1926, and because

revision and amending of seismic design codes have been made based on bitter

experiences learned from a number of seismic damage in the past, seismic

performance of highway bridges designed by the current seismic design code is

considered adequate. However, there are a number of existing bridges

vulnerable to seismic effects, which were designed by the past design practices.

By the great efforts in the past seismic strengthening works, installation of

falling-off prevention device is now almost being completed for important

bridges, but seismic strengthening of foundations and piers have been made for

few bridges. Therefore it is now facing to a time to initiate seismic

strengthening of foundations and piers. For this purpose, it is absolutely

important to develop a reliable seismic inspection method of existing highway

bridges. Further research efforts for improving reliability and accuracy of

seismic inspection method is required as well as development for seismic

strengthening method.

FUTURE DHiECTION

It is required to develop various subjects for seismic inspection and seismic

strengthening including the following issues :

a) Level of Seismic Strengthening

There is no wonder to require strengthening for those bridges vulnerable to

developing critical failures such as falling-down during an earthquake.

However, from the view of importance of highway bridges as a vital component of

transportation facilities, a certain type of bridges requires to keep their

function without causing damage even after a destructive earthquake. On the

other hand, there may be bridges which were constructed in old time and are

now in use for a few amount of traffic. Depending on importance, impact causing

indirect damage, difficulty for repair and service time left before replacement,

an appropriate evaluation method for deciding priority of seismic

strengthening and for deciding the target level required for strengthening is

important.

b) Improvement of Reliability of Seismic Inspection

It is required to have more reliable evaluation on the seismic performance of

bridges for spending a big amount of budget such as for seismic strengthening

of foundations. The point required in the seismic inspection is not to loiow

whether the design of a highway bridges is appropriate in accordance with the

current design specifications, but to know whether the bridge could perform in

a way expected in accordance with the target of seismic strengthening during

an anticipated earthquake. Much more improvement on the structural

122
performance is required.

c) Development of Seismic Strengthening Method for Vulnerable Highway Bridges

Because there are several possible modes which lead to critical failure of

highway bridges, development of seismic strengthening method is required for

them. These includes the strengthening method for bent pile foundation,

reinforced concrete frame on two independent caisson foundations and plain

concrete piers. Strengthening method of reinforced concrete piers with

termination of main reinforcement with inadequate anchorage length is also

important. Strengthening methods by applying new materials such as carbon

fiber and fiber reinforced plastic, and new technology such as connection of

adjacent girders or slabs, non-destructive inspection method and devices for

preventing falling-off of superstructure with energy absorbing capability are

also to be developed.

REFERENCES

1) Arakawa, T. and Kawashima, K. : Seismicity and Maximum Possible Earthquakes

around Japan for Application to Seismic Risk Analysis, Technical Note of

PWRl, Vol. 2098, Public Works Research Institute, Ministry of Construction,

1984

2) Iwasaki, T. , Penzien, J. and Clough, R., W. : Literature Survey - Seismic

Effects on Highway Bridges, Report No. EERC 71-11, Earthquake Engineering

Research Center, University of California, Berkeley, 1972

3) Kawashima, K. : Seismic Design, Seismic Strengthening and Repair of Highway

Bridges in Japan, U.S. -Japan Workshop on Seismic Retrofit of Bridges, Public

Works Research Institute, Tsukuba, Japan, December 1990

4) Ministry of Construction : Economic Surveys of Road Traffic, 1971- 1990

5) Ministry of Construction : The Construction White Papers, 1971-1990

6) Japan Road Association : Part V Seismic Design, Design Specifications of

Highway Bridges, February 1990

7) Japan Road Association : Countermeasures for Roads against Earthquakes,

March 1986

8) Kawashima, K. and Unjoh, S. : An Inspection Method of Seismically Vulnerable

Existing Highway Bridges, Structural Eng. /Earthquake Eng., Vol.7, No.l,

Proc. Japan Society of Civil Engineers, April 1990

9) Japan Road Association : Guide Specifications for Earthquake Hazard

Mitigation for Transportation Facilities - Pre-Earthquake Countermeasures

-, February 1987

10) 0kawa, S., Maeda, Y., Kawashima, K. and Saeki, M. : Large Earthquake

Countermeasures for Tomei Expressway Bridges, 4th Joint U.S. -Japan

Workshop on Bridge Engineering Performance, Strengthening, and Innovation,

San Diego, California, USA, May 1988

11) Tsubouchi, T., Ohashi, K. and Arakawa, K. : Large Earthquake Countermeasures

for Bridge Substructures on the Tomei Expressway, U.S. -Japan Workshop on

Seismic Retrofit of Bridges, Public Works Research Institute, Tsukuba, Japan,

123
December 1990

12) Kawashima, K., Unjoh, S. and Azuta, Y. : Examples of Seismic Strengthening of

Highway Bridges, Technical Note of PWRI, Vol.2674, Public Works Research

Institute, Ministry of Construction, October 1988

13) Narita, N., Murakami, M. and Asanuma, H. : Report of the Investigation on

Earthquake Damage to Shizunai Bridge, 15th Joint Meeting, U.S. -Japan Panel

on Wind and Seismic Effects, UJNR, Tsukuba, Japan, May 1983

14) Public Works Research Institute : Disaster Caused by the Miyagi-ken-oki

Earthquake of 1978, Report of PWRI, Vol.159, March 1983 (in Japanese)

15) Kawashima, K., Unjoh, S. and lida, H. : Seismic Inspection and Seismic

Strengthening of Reinforced Concrete Bridge Piers with Termination of Main

Reinforcement at Mid-Height, U.S. -Japan Workshop on Seismic Retrofit of

Bridges, Public Works Research Institute, Tsukuba, Japan, December 1990

16) Akimoto, T., Nakajima, H. and Kogure, F. : Seismic Strengthening of

Reinforced Concrete Bridge Piers on Metropolitan Expressway, U.S. -Japan

Workshop on Seismic Retrofit of Bridges, Public Works Research

Institute, Tsukuba, Japan, December 1990

17) Matsuura, Y., Nakamura, I. and Sekimoto, H. : Seismic Strengthening of

Reinforced Concrete Bridge Piers on Hanshin Expressway, U.S. -Japan

Workshop on Seismic Retrofit of Bridges, Public Works REsearch Institute,

Tsukuba, Japan, December 1990

18) Matsuda, T., Sato, T., Fujiwara, H. and Higashida, N. : Effect of Carbon Fiber

Reinforcement as a Seismic Strengthening Measure for Reinforced Concrete

Bridge Piers, U.S. -Japan Workshop on Seismic Retrofit of Bridges, Public

Works Research Institute, Tsukuba, Japan, December 1990

19) Yamamoto, T., Ishibashi, T. , Otsubo, M. and Kobayashi, S. : Experimental

Studies on Seismic Resistant of a Pier with Reinforcement Terminated in a

Tension Zone, Proc. Japan Society of Civil Engineers, Vol.348/V-l, August

1984

20) Miyamoto, M. , Ishibashi, T. and Saito, T. : Experimental Studies on Seismic

Strengthening Method of Existing Bridge Piers by Steel Jackets, Technical

Note of Japan Railway Corporation, Vol.89, Institution of Japan Railway

Facilities, March 1987

21) Kawashima, K., Ichimasu, H. and Kodera, J. : Basic Principle/ Ichimasu, H.,

Kodera, J. and Kawashima, K. : Design Details/ Kawashima, K., Ichimasu, H. and

Kodera, J and Tanaka, Y. : Example of Applications/ Kawashima, K., Ichimasu,

H. and Ohuchi, H. : Seismic Strengthening, International Workshop on Seismic

Design and Retrofitting of Highway Bridge, Bormio, Italy, April 1991

22) Roberts, J., E. : Bridge Seismic Retrofit Program for California Highway

Systems, Proc. 3rd U.S. -Japan Workshop on Earthquake Disaster Prevention

for Lifeline Systems, Public Works Research Institute, Tsukuba, Japan, May

1989

23) Priestley, M., J., N. : Seismic Retrofitting of Bridge Columns for Enhanced

Shear Strength and Flexible Ductility, Proc. 3rd U.S. -Japan Workshop on

Earthquake Disaster Prevention for Lifeline Systems, Public Works Research

Institute, Tsukuba, Japan, May 1989

124
RECENT ADVANCES IN SEISMIC DESIGN AND RETROFIT OF

CALIFORNIA BRIDGES

James E. Robert s , F . ASCE^

ABSTRACT

This paper describes the damage and lessons learned from the most

recent major earthquakes, the resulting bridge seismic design and

detailing changes and the seismic retrofit program implemented by

the California Department of Transportation after the 1971 San

Fernando Earthquake and accelerated after the 1989 Loma Prieta

earthquake. The goal of the program is to reinforce most of the

bridges designed and constructed prior to acquiring the current

levels of knowledge of seismic loading and structure response

(about 1978) to improve their structural ductility and resistance

to the major factors which contributed to damage and collapse in

the San Fernando and Loma Prieta events. The program has been

executed in two phases. The initial phase, completed in 1988 at a total cost of $54 million, provided reinforcement to superstructures of 1260 bridges by connecting all narrow expansion

joint seats with hinge restrainers and anchoring girders and other

superstructure elements to the substructure. The $3.4 billion

single and multiple column retrofit phase, now under active

implementation, is designed to reinforce substructure elements and

create ductile members by increasing confinement. A Risk Analysis

procedure was developed to prioritize the bridges for seismic ~ upgrading so that highest risk bridges are retrofitted first.

Legislation was recently enacted to require the Department of

Transportation to also take the lead role in seismically

retrofitting all locally owned bridges in the state. Research has

been conducted, and is currently underway, at the University of

California, San Diego to test and confirm the validity of several

proposed design solutions for seismic retrofitting of existing

bridge single column bent substructure elements. Since the Loma

Prieta earthquake additional research is being conducted at the

University of California at Berkeley, San Diego, Irvine and Davis

to develop and test retrofit techniques for multiple column bents

and double level structures, including abutment and footing

details. Some full scale testing was completed on a standing

portion of the Cypress Street viaduct in Oakland to determine its

fundamental response characteristics and to test some techniques

which may be applied to the double deck structures in San

Francisco and on complex structures with outrigger supports and

other non standard support configurations throughout the state.

BACKGROUND

The 1971 San Fernando earthquake caused substantial damage to

recent bridge construction and exposed' a number of deficiencies in

the bridge design specifications of that time. These deficiencies

have the potential to impact dramatically on transportation lifelines and the traveling public today. Bridge design specifications

were immediately modified to correct the identified deficiencies on

Chief, Division of Structures, California Department of Transportation, P.O. Box 942874, Sacramento, CA 94274-0001

125
newly designed bridges. Structures in-place however, have served to

be a substantially more challenging problem. Research was undertaken

both in the United States and overseas to improve analytical techniques, and to provide basic data on the strengths and deformation

characteristics of lateral load resisting systems for bridges.

Damage to long multiple level bridges from the October, 1989 Loma

Prieta earthquake showed the need to more carefully consider

longitudinal resisting systems because earthquake forces cannot be

carried into abutments and approach embankments as they can on

shorter briages

.

The initial phase of the Bridge Seismic Retrofit Program

involved installation of hinge and joint restrainers to prevent deck

joints from separating. This was the major cause of bridge collapse

during the San Fernando earthquake and was judged by Caltrans

engineers to be the highest risk to the traveling public. Included

in this phase was the installation of devices to fasten the

superstructure elements to the substructure to resist vertical

accelerations and also to prevent superstructure elements from

falling off their supports. This phase was essentially completed in

1989 after approximately 1,260 bridges on the State Highway System

had been retrofitted at a cost of over 55 million dollars.

While the hinge and joint restrainers performed well, shear

failure of columns on the I-605/I-5 separation bridge in the

moderate Whittier Earthquake of October 1, 1987 reemphasized the

inadequacies of pre-1971 column designs. Even though there was no

collapse, the extensive damage resulted in plans for basic research

into practical methods of retrofitting bridge columns on the

existing pre-1971 bridges. The research program was initiated in

early 1987 and is currently being conducted at the University of

California at San Diego. Funding levels for implementation were

increased four fold after the Whittier earthquake.

The Loma Prieta earthquake of October 17, 1989 again proved the

reliability of hinge and joint restrainers but the tragic loss of

life at the Cypress Street Viaduct on 1-880 in Oakland emphasized

the necessity to immediately accelerate the column retrofit phase

with a higher funding level for both research and implementation.

Other structures in the earthquake affected counties performed well,

suffering the expected column damage without collapse. With the

exception of an outrigger column-cap confinement detail, those

bridges using the post-1971 design specifications and confinement

detail changes performed well. Research and analysis subsequent to

the Loma Prieta event have shown conclusively that a column pedestal

detail unique to the Cypress structure was the main cause of the

total collapse. The effect of the response of deep soft soils in

the structure foundations also proved to be a contributing factor

which must be analyzed and included in future design procedures,

especially for long, tall structures with relatively high periods of

vibration

.

PRE AND POST 1971 COLUMN DESIGN

Bridge columns designed before the 1971 San Fernando earthquake

typically contain very little transverse reinforcement. A common

detail for both circular and rectangular columns consisted of #4

(12.7 mm diam.) transverse peripheral hoops at 12 inch to 18 inch

126
(300 mm to 450 mm) centers, regardless of column size and area of

main reinforcement. Also, it was common practice to extend short

lengths of dowel or tails on the footing reinforcing steel out of

the footing and lap splice the main column reinforcing steel cage at

that point. As a consequence of these details, the ultimate

curvature capable of being developed within the potential plastic

region is limited by the strain at which the cover concrete starts

to spall. The result is flexural failure resulting from inadequate

ductility capacity, or shear failure due to lack of adequate shear

reinforcement. Tests conducted at UC San Diego confirm this theory.

Several bridges suffered column shear failures due to the elastic

design philosophy under which they were designed prior to 1971.

Columns designed since 1971 contain a slight increase in the

main column reinforcing steel and a major increase in confinement

steel over the pre-1971 designs. All new columns, regardless of

geometric shape, are reinforced with one or a series of spiral wound

circular cages. The typical transverse reinforcement detail now

consists of #6 (19 mm diam.) hoops or spiral at three inch (76 mm)

pitch. This provides approximately eight times the confinement

reinforcing steel in columns than what was used in the pre 1972

non-ductile designs. All main column reinforcing is continuous into

the footings and superstructure. Splices are mostly welded or

mechanical, both in the main and transverse reinforcing. Transverse

reinforcing steel is designed to produce a ductile column by

confining the plastic hinge areas at the top and bottom of columns.

RETROFIT PHILOSOPHY

There are some 24,000 highway structures for which the State of

California is responsible in some capacity. It is economically

unrealistic to suggest that every structure be immediately

retrofitted to withstand maximum magnitude earthquakes without some

damage. The retrofit philosophy adopted at the start of the

Restrainer Retrofit Phase of the program offers reasonable direction

to the remaining phases of the Retrofit Program.

It was and still is Caltrans philosophy to first retrofit those

structures which pose the greatest risk to the public and are the

most vital to the transportation system. The ultimate goal is to

see that all of the bridges in the state will be capable of

surviving maximum credible earthquakes without collapse. Some damage

is inevitable but, with proper retrofitting, it is believed that

collapse is preventable and, further, it is believed that damage can

be held to a minimum, to the ' extent that the critical elements of

the transportation system can remain open and functioning during a civil disaster or during repair. As we get into the actual analysis

and design it is becoming apparent that retrofitting many older

structures to this standard may not be cost effective. It is highly

probable that we may have to accept some period of closure on many

structures to effect repairs . It is also apparent that some

structures will be replaced rather than retrofitted simply as an

economic decision. Time and further analysis will bring this

problem to the decision makers. As a direct result of the one month

loss of the San Francisco-Oakland Bay Bridge during the Loma Prieta

earthquake, it has been recommended that major transportation

structures be designed for higher elastic seismic force levels and

longer shaking periods to reduce the damage to non structural type.

127
To accomplish this goal a new "importance factor" will be introduced

into the design and retrofit criteria. This represents a major

change in the seismic design criteria for bridges.

PRIORITIZATION PROCEDURE

Identification of bridges likely to sustain damage during an

earthquake was an essential first step in the Bridge Seismic

Retrofit Program. Damage analysis after the San Fernando earthquake

led the caltrans bridge engineers to the conclusion that unconnected

joints at hinges, bents and abutments posed the highest threat to

collapse. It was also determined that single column supported bents

posed the next highest threat. These judgements were documented as

policy in 1973 and have been confirmed by performance of both

retrofitted and non retrofitted bridges in several subsequent

earthquakes. The overwhelming evidence from Loma Prieta supports

the priority of retrofit that had been established in 1973 after

analysis of bridge damage caused by the San Fernando earthquake.

After the hinge restrainer phase of the retrofit program was

completed, the department began to prioritize the single and

multiple column supported structures for sequence of upgrading.

What can be classified as a level one risk analysis was employed as

the framework of the process which led to a consensus list of risk

prioritized bridges.

A conventional risk analysis produces a probability of failure

or survival. This probability is derived from a relationship

between the load and resistance sides of a design equation. Not

only is an approximate value for the absolute risk determined, but

relative risks can be obtained by comparing determined risks of a number of structures. Such analyses generally require collections

of large quantities of data to define statistical distributions for

all or at least the most important elements of some form of

analysis, design and/or decision equations. The acquisition of this

information can be costly if obtainable at all. Basically, what is

done is to execute an analysis, evaluate both sides of the relevant

design equation, and define and evaluate a failure or survival

function. All of the calculations are carried out taking into

account the statistical distribution of every equation component

designated as a variable throughout the entire procedure. To avoid

such a large time consuming investment in resources and to obtain

results which could be applied quickly as part of the Single Column

Phase of the Retrofit Program, an alternative was recognized.

What can be called a level one risk analysis procedure

was used. The difference between a conventional and level

one risk analysis is that in a level one analysis judgements

take the place of massive data supported statistical

distributions

.

* This level one risk analysis has been revised several times and

will be continually improved with time and more information. The

bridges, especially those in the mid-range of the risk list, will be

repriorit ized and the risk lists revised. Meanwhile, we were able

to identify the most critical or highest risk bridges and get

retrofit contracts underway. With the prediction of activity on

nearby faults within three to seven years, Caltrans did not have the

128
luxury of time to conduct a conventional risk analysis. The level

one risk analysis procedure we used can be summarized in the

following steps

1 . Identify major faults with high event probabilities

(priority one faults)

,

This step was carried out by consulting the California Division

of Mines and Geology and recent US Geological Survey studies . A

team of seismologists and engineers' identified seismic faults

believed to be the sources of future significant events. Selection

criteria included location, geologic age, time of last displacement

(late quarternary and younger), and length of fault (10 km min . )

.

Each fault recognized in step 1 was evaluated for style, length, dip

and area of faulting in order to estimate potential earthquake

magnitude. Known faults were placed in one of three categories;

minor (ignored for the purposes of this project), priority two

(mapped and evaluated but unused for this project) , or priority one

(mapped, evaluated, and recognized as immediately threatening)

.

Despite the fact that we use Maximum Credible events for analysis of

a typical bridge, we have completed a form of probabilistic approach

in the above procedure. On major structures a comprehensive hazard

analysis, using the probabilistic approach is conducted. After

identification of single column supported bridges close to priority

one faults the single column program was initiated. After the Loma

Prieta earthquake it was decided that all remaining structures were

to be evaluated equally, regardless of whether they were affected by

priority one or priority two faults.

2 . Develop attenuation relationships at faults identified in

step 1

.

An average attenuation model was developed by Mualchin of the

California Division of Mines and Geology to be used throughout the

state. It is the average of several published models. Mualchin, a well known seismologist, is now a member of the Caltrans Office of

Earthquake Engineering

3. Define the minimum ground acceleration capable of causing

severe damage to bridge structures

.

The critical (i.e., damage causing) level of ground acceleration

was determined by performing nonlinear analyses on a typical highly

susceptible structure (single column connector ramp) under varying

maximum ground acceleration loads. The lowest maximum ground

acceleration that demanded the columns to yield (provide a ductility

ratio of 1.3) was defined as the critical level of ground

acceleration. That level of ground acceleration was 0.5g. Loma

Prieta proved this assumption to be wrong and adjustments have been

made in current evaluations. Based on input from our Geologists and

the type of material over the bedrock, an acceleration level as low

as 0.25g could be critical.

4 . Identify all the bridges within high risk zones defined

by the attenuation model of step 2 and the critical

acceleration boundary of step 3.

129
The shortest distance from every bridge in California to the two

closest priority one faults was calculated. Each distance was

compared to the distance from each respective level of magnitude

fault to a 0.5g decremented acceleration boundary. If the distance

from the fault to the bridge was less than the distance from the

fault to the 0 . 5g boundary, the bridge was determined to lie in the

high risk zone and was added to the screening list for

prioritization. The prioritization procedure is described below.

The Caltrans Division of Structures has developed a computerized

data base which has the coordinates of all 24,000 State, County and

City bridges stored. We can produce a map of the entire state or

any portion of the state showing the bridges, the major faults and

an overlay of the combinations. These maps can be viewed on the

computer screen or printed for use by designers in screening to

identify high risk bridges. The procedure is quite simple, using the

computer data base

.

1 . Locate all Highway Bridges on the State System

2. Locate all Earthquake Faults

3. Determine those structures that are in a high risk zone.

5 . Prioritize the threatened bridges by summing weighted

bridge structural and transportation characteristic

scores .

This step constitutes the process used to prioritize the bridges

within the high risk zones to establish the order of bridges to be

investigated for retrofitting. It is in this step that a risk value

is assigned to each bridge. A specifically selected subset of bridge

structural and transportation characteristics of seismically

threatened bridges was drawn from the California Department of

Transportation structures computer database. Those characteristics

were

Ground Acceleration

Route Type-Major or Minor

Average Daily Traffic (ADT)

Column Design-Single or Multiple Bents

Confinement Details of Column (relates to age)

Length of Bridge

Skew of Bridge

Availability of Detour

After evaluating the results of the 1989 Loma Prieta earthquake,

Caltrans engineers modified the Risk Analysis Algorithm by adjusting

the weights of the original characteristics and adding the following

new characteristics to the list. A total of 18 different characteristics are now evaluated. One of the most important new factors is

the soil type at the site; this is due to the significant influence

of deep soft soils on structure performance during the Loma Prieta

event . The addition of exposure and type of facility crossed

recognize the higher damage and loss effects of long structure

failure and those on high volume traffic routes.

130
Soil Type

Hinges, Type and Number

Exposure (Combination of Length, Height & ADT)

Abutment Type

Type of Facility Crossed

All of the components listed above were considered in the

Caltrans risk evaluation, A team of experts representing hundreds

of years of experience in the fields of bridge design, construction

and maintenance engineering and geotechnical and geological sciences

were employed to identify and weight appropriate risk components.

Normalized preweight characteristic scores from 0.0 to 1.0 were

assigned based on the information stored in the database for each

bridge. Scores close to 1.0 represent "high risk structural" characteristics or "high cost of loss" transportation characteristics. The

preweight scores were multiplied by prioritization weights. Postweight scores were summed to produce the assigned prioritization

risk value

.

In summary, an evaluated risk number is calculated respecting

source, distance, local geologic site conditions, bridge structural

components and what is at risk in addition to the bridge.

Determined risk values are not to be considered exact. Due to

the approximations inherent in the judgements adopted, the risks are

no more accurate than the judgements themselves . The exact risk is

not important. Prioritization list qualification is determined by

fault proximity and empirical attenuation data and not so much

judgement. Therefore, a relatively high level of confidence is

associated with the risk ranking and identified bridges on the

initial list of threatened bridges. Relative risk is then used to

establish the order of bridges to be investigated in detail for

possible need of retrofit by the designers . The risk analysis

offers consistency in applying the judgements adopted to all bridges

in the state.

A number of assumptions were made in the process of developing

the prioritized list of seismically threatened bridges. This is

typical of most engineering projects. These assumptions are based

on what is believed to be the best engineering judgement available.

It seems reasonable to pursue verification of these assumptions some

time in the future to insure that we have not missed anything. Two

steps seem obvious: (1) monitoring the results of the design

engineer's retrofit analyses, and (2) executing a higher level risk

analysis where necessary and better data are available.

Important features of the prioritization procedure are the ease

and minimal cost with which it was carried out and the database,

highlighting bridge characteristics, to identify structures in need

of retrofit. This database will serve as part of the statistical

support for the current risk analysis and of any future conventional

risk analysis. The additional accuracy inherent in a higher order

risk analysis will serve to verify previous assumptions, provide

very good approximations of actual structural risk, and develop or

evaluate postulated scenarios for emergency responses . In the

interest of getting the job accomplished the shorter procedure has

been used and the entire 24, 000 bridge inventory has been risk

analyzed. More detailed analyses can now be utilized to fine tune

131
the list but it is reasonable to analyze only selected structures

for this purpose. The original lists of 12,000 local and 12,000

state bridges were reduced to 4000 local and 7000 state bridges

which require more detailed review and, in many cases, dynamic

analysis. In the next step a manual screening process is being used

which includes review of "AS-Built" plans by three engineers to

identify bridges with column and footing details that appear to need

upgrading. Some structures were eliminated based on details,

location and other judgement factors. In the final analysis, our

designers and field maintenance and construction engineers are being

asked to just look at bridges with which they are familar and alert

us to any they question. No risk algorithm will replace common

sense and judgement, however, it is an excellent method of screening

large numbers of bridges to begin the process.

DESIGN

The California Department of Transportation implemented the

single column phase in 1986 and the multiple column phase (covering

all remaining bridges) of the Bridge Seismic Retrofit Program in

1990. In the current program entire structures may be subject to

modification to reduce the likelihood of catastrophic failure during

a large earthquake . The main goal of the program is to prevent

collapse, but a secondary goal is to increase serviceability by

reducing damage to a level that can be repaired without closing the

structure to traffic. This is a goal that may have to be modified

as cost-benefit considerations are evaluated. Special attention is

being focused on overall structure response. Two key items are

recognized as being primary in achieving this goal: (1) providing

continuity in superstructures at joints to prevent supported

elements from collapsing, and (2) increasing ductility at certain

locations throughout the structure and specifically in columns and

column-superstructure and column-footing joints. The key to the

column retrofit phase is ductility provided by the supplemental

external confinement and improvements to foundations and abutments.

Currently, that external confinement consists of steel shells

designed to resist the column shear forces and provide confinement

of main column reinforcing at the plastic hinge location. Other

techniques for wrapping with cables or fiber reinforcing are also

being tested. Foundations and abutments are being reinforced with

additional piles, confinement reinforcement, soil anchors, pile

shaft retainers, bolster walls and other details to improve seismic

resistance

.

Design engineers have been assigned the final task of verifying

or discrediting the prioritized bridges' need for retrofitting and

then, if necessary, developing retrofit contract plans. Verification of the need for retrofit is necessary due to the possibility

of prioritized bridges already being capable of withstanding the

maximum credible earthquake. This can only be determined by

additional analysis and will be the case when judgements made in the

prioritization process prove to be too conservative. Emphasis is

being placed on evaluation of the total bridge during this design

phase. In most cases a dynamic analysis is necessary before the

final decision to retrofit or not can be made. Results from current

research and analysis indicate that we have been too conservative in

the strength assessment of existing non-ductile structures. It is

probable that application of higher allowable ductility factors in

132
the analysis of these older structures will reduce the total number

that must be retrofitted or that the amount of retrofitting on each

structure can be reduced.

A number of structure modification schemes are under consideration in the bridge seismic retrofit program (since the Loma

Prieta earthquake the Single and Multiple Column phases of the

program have been combined with the old superstructure phase into

the single, "Bridge Seismic Retrofit Program" with no phases) . Restrainer and superstructure retrofit techniques which have proven

to be successful during recent earthquakes will continue to be used

to effectively force superstructures to act more like single units.

The problems associated with preventing the type of substructure

failures seen at San Fernando, Whittier and Loma Prieta are

complicated. If all columns are made to carry earthquake loads,

then so must the footings and the pile groups. This is not an

acceptable solution economically. Some columns may be allowed to

pin at a point of contraf lexure under dynamic loading while selected

retrofitted columns and the abutments absorb the seismic energy and

continue to hold the damaged bridge up, preventing bridge collapse.

Substructure modifications are currently being evaluated by

researchers at the University of California, Berkeley and San Diego.

The conclusions drawn from their work will be used to standardize

retrofit design schemes. All retrofit designs are subjected to

intense scrutiny by a group of experienced design supervisors,

seismologists, geologists and dynamic analysis experts in a "strategy meeting" where the project designer must justify design

assumptions and retrofit schemes. These sessions often require

several hours and may result in major redesign to achieve an

acceptable solution. In addition. Seismic Safety Peer Review Panels

of acknowledged experts in structural engineering and seismology are

utilized to review the design criteria, assumptions and final plans

on major, complicated structures

.

RETROFIT DETAILS

Some typical superstructure retrofit methods used to date have

been to add restraining cables or rods at piers and hinges and add

shear keys at abutments . In some cases new, longer hinge and

abutment bearing seats had to be installed. Where this was not

practical heavy duty pipe hinge extenders were installed to resist

both horizontal and vertical seismic forces. Additionally, these

hinge extenders carry the supported portion of a bridge in the

unlikely event it were to move off the narrow hinge bearing seat . The continuing Legislatively mandated Bridge Seismic Retrofit

Program will include this type of retrofitting on all state and

other publicly owned bridges (i.e. County, City, Transit Systems,

Other State agencies) . Column ductility will be increased by the installation of

external confining jackets to provide the concrete confinement now

provided internally in new design details by the spiral reinforcing

cages. These external jackets are primarily structural steel but we

have tested and will begin using fiberglass wrapped jackets and

possibly prestressing strand if construction details for wrapping

around small diameter members can be developed. On single column

supported bents the columns and footings must both be retrofitted to

provide resistance to overturning from lateral forces , Most footings

133
on the older structures must be rebuilt with the addition of top

reinforcing steel mats and additional piles or soil anchors to

provide the required additional overturning resistance. In many

cases "super bents" must be constructed in areas that are accessible

and out of the way of traffic. These bents are designed to take

most of the lateral forces and preclude or reduce the need for

retrofit on columns near traffic lanes.

Work is beginning on the multiple column structure retrofit as

research results become available. On most of the multiple column

supported structures hinges can be allowed at the top of footing and

this precludes the need for footing reinforcement. Most of the

details are similar to those used on single column supports. The

total program will consist of retrofitting approximately 4500

bridges on the state system and 1500 bridges on the local city and

county systems. Priority of funding and implementation will be

given to the 750 bridges on the state system and 180 bridges on the

local system which must be under contract by December 31, 1993 to

meet the current Seismic Safety Criteria. The remaining bridges

will be retrofitted primarily to reduce future damage and will be

programmed over the last half of the decade. During this period we

will go back and look at all original phase I bridges again to

insure that none are missed by the initial screening processes.

RESEARCH AND PROOF TESTING

Work at the University of California at San Diego was funded in

1987 and consisted of half scale model testing of the various single

column bent retrofit techniques. Theoretical calculations and

research work previously conducted in New Zealand by Doctor Nigel

Priestley showed that enclosing the columns in steel casings could

significantly increase their shear strength and ductility by

providing the additional confinement at the hinge areas. A series

of tests have been completed on round columns with outstanding

results. Based on this work, the first contracts for bridge column

retrofit were advertised in January, 1990 and work is underway in

the Los Angeles area on more than 100 bridges. By the end of 1991

we will have approximately 277 bridges under contract for retrofit

statewide. A second series of tests was begun in February, 1990 on

rectangular single column bents and the results are being

implemented now. Both series of tests include models of the

prototype columns with the pre-1971 reinforcing details without

retrofitting, retrofitted columns using the steel shell confinement

and a post damage retrofitted column using the steel shell to

determine whether a non-retrofitted damaged column can be salvaged

after an earthquake. Typical displacement ductility factors on

retrofitted undamaged columns are 6 to 8 . On the post damage

retrofitted column a ductility factor of 2 was achieved. Even

though displacement ductility factors of 6 to 8 have been common in

these first tests, our analysis procedure is based on moment

ductility demand no greater than 4 . Tests have recently been

conducted on columns retrofitted by wrapping pre-stressing strand

and fiber reinforced sheet wrapping similar to the technique used on

large concrete tanks and industrial smoke stacks. Initial results on

the fiber wrapped technique are encouraging and contracts will be

advertised to test the construct ibility and cost effectiveness of

this procedure. Additional tests are scheduled to be conducted on

these and other retrofit techniques and specific details.

134
Work has recently been funded at both UC San Diego and UC

Berkeley to build and test half scale models of column cap outrigger

bent joints and will be available this summer (1991) . The most

complex model test of the series will be conducted during the summer

(1991) on half scale models of the edge beam-column connections

proposed for strengthening the double deck viaducts in San

Francisco. One of the major problems which will be addressed in

this model construction is construct ibility of the complex joints.

Work at UC Berkeley is also funded and was started in November,

1990 to test retrofit techniques on other types of multiple column

bents. These substructure configurations are more complex and

difficult to retrofit but they have not demonstrated as high a risk

as do single column supports. During the aftermath of the Cypress

Street Viaduct cleanup efforts a three span segment of the standing

portion of the viaduct was instrumented and tested by the University

of California researchers to determine its fundamental period.

Column jacketing retrofit techniques proposed for use on the double

deck viaducts in San Francisco were tested to prove their

theoretically calculated value and actual reliability in increasing

column ductility and shear capacity. This was a unique opportunity

to test full scale structure frames to yield, apply several

retrofitting techniques and retest the upgraded structure. The

results have been published by the University and offer some degree

of confidence for use in very specific applications. Lateral load

tests of several new types of foundation piles are also scheduled,

especially in the San Francisco area where soft soils pose a problem

in developing uplift capacity to resist overturning moments.

Lateral load capacity tests of large diameter piles up to seven feet

will also be conducted at the sites of new construction.

SUMMARY

The procedure used by the California Department of

Transportation to identify and prioritize seismically threatened

bridges to be investigated for possible retrofit has been presented.

The original decision to retrofit deck joints first and columns

later was based on experience from the 1971 San Fernando earthquake.

Subsequent earthquakes, including the recent Loma Prieta event, have

proved the validity of this decision. Several hundred bridges with

only the deck joint restrainers in place have performed well during

these earthquakes. The level one risk analysis used to prioritize

the structures in the single column phase was discussed in which

decisions were made based on reasonable judgement instead of massive

statistical data. The level one risk analysis offers a procedure to

consistently apply knowledge gained from past earthquakes and known

characteristics of bridges throughout the state which can be carried

out quickly without developing a large, more sophisticated

statistical database. Steps will be taken to verify assumptions

made in the risk analysis in an attempt to improve confidence in

this analysis . A modification of this risk analysis procedure will

be used to prioritize the more complex bridges remaining in the

program as the candidate list is screened. Research on column

retrofit techniques will be continued to refine and improve those

techniques. Research on the effects of soft foundation materials

and the effects of variable foundation material response on long

structures will also be continued.

135
^ Finally, the legislative direction and funding is being made available to accelerate the California Bridge Seismic Retrofit

program for all publicly owned bridges which require upgrading to

meet modern Seismic Safety Standards.

136
III. SEISMIC DESIGN & ANALYSIS:

PIPELINES & TUNNELS,

PART ONE

"Repair and Rehabilitation of Buried Water and Sewer Lifelines'

L.R.L. Wang, H. Kennedy

"Investigations on External Force Evaluation in the

Seismic Deformation Method"

N. Takahashi, M. Takeuchi, K. Irokawa

"Estimation of System Reliability for Lifeline Standards and

Example Using the City of Everett, Washington Lifelines"

D. Ballantyne

"Dynamic Response of Twin Circular Tunnels during Earthquake

T. Okumura, N. Takewaki, K. Shimizu, K. Fukutake

"Development of Seismic Design and

Construction Standards for Lifelines"

R. Dikkers

137

REPAIR AND REHABILITATION OF BURIED WATER AND SEWER LIFELINES

Leon R.L. Wang

Professor of Civil Engineering

Old Dominion University

Norfolk, VA 23529, USA

and

Harold Kennedy

Vice President of research & Development

EBAA Iron Inc. Eastland, TX 76448, USA

ABSTRACT

Buried water and sewer pipelines have been damaged heavily by recent earthquakes that

included the 1985 Mexico City earthquake, the 1987 Whittier, California earthquake and

the most recent Loma Prieta earthquake of October 17, 1989. Existing buried pipelines are unsafe even under moderate earthquakes, because most existing water and sewer

pipelines have been built without seismic considerations.

The paper describes an ongoing research on repair and rehabilitation of buried water and

sewer pipelines for seismic resistance. The project is sponsored by the National Science

Foundation and co-sponsored by EBAA Iron Inc., an industry that contributes to the

testing program of pipe joints and participates in the overall study. The objectives of the

research are (1) to review/synthesize current methods for inspection/detection of

damaged/deteriorated pipelines;(2) to document/develop cost-effective methodologies for

repair and restoration of damage pipelines and to (3) develop/recommend guidelines/

strategies for effective rehabilitation and strengthening of vulnerable pipelines.

INTRODUCTION

Earthquakes are perhaps the most devastating and destructive in nature. They are unpredictable at the present time and can be violent. Due to the increase of population

and the concentration of inhabitants in urban areas, the need to protect human lives and

to mitigate the economic loss become increasingly urgent.

Buried lifelines which include water, sewer, gas and oil pipelines have been damaged

heavily by earthquakes including the 1985 Mexico City earthquake[1], the 1987 Whittier,

California earthquake[2] and the most recent Loma Prieta earthquake[3] of October 17,

1989. Existing buried lifelines are unsafe even under moderate earthquakes.

d:uJnr91.rrT

139
Because of the importance of lifelines to the health, supply, and safety of the public,

lifeline earthquake engineering has drawn the attention of the engineering profession in recent years. Since there is still no codified seismic provision to design buried lifelines,

most water and sewer pipelines, including relatively new ones, have been built without

adequate earthquake protection. Damages to water and sewer pipelines during

earthquakes are unavoidable and economic loss can be substantial. Effective repair

methods under emergency situations and for a permanent basis must be developed. Due

to the fact that the replacement of all existing water and sewer pipelines is very

expensive, if not impossible, the development of effective rehabilitation techniques and

strategies is urgently needed.

BACKGROUND

In general there are four causes of seismic hazards to buried water and sewer pipelines,

namely:

a) soil straining induced by seismic ground shaking, (i.e. wave propagation effect);

b) differential ground movement/rupture along fault zone, lateral soil spreading or

landslides;

c) soil liquefaction induced by ground shaking;

d) earthquake induced internal hydrodynamic surge pressure in water pipes.

Over all, the most frequent failure modes as reported by several investigators [4, 5] were

pulled-out of joints and/or cnjshing of pipe bodies due to seismic shaking in the

longitudinal direction; shear and/or bending failures (cracks or fractures) due to soil lateral

spreading/ground movement in the transverse direction; longitudinal cracks and bursting

holes due to internal pressure and uplift/sinking due to soil liquefaction.

One of the most important elements for repair and rehabilitation of buried water and

sewer pipelines would be the pipeline joints/couplings or junctions. However seismic

resistant characteristics and energy absorption capability of commonly used joints, bends

and junctions are not well understood.

This project also intends to carry out experimental evaluations (statically and dynamically)

of some typical (commonly used and newly developed) pipe joints, bends and junctions

that can be used effectively for repair and rehabilitation of buried pipelines.

ISSUES CONCERNING REPAIRS AND RETROFIT

Repairs of lifelines may be classified into two categories, a) emergency or temporary

repairs and b) permanent or complete repairs. Various temporary and permanent repair

methodologies should be developed and transferred to the users for implementation. In fact some repair methods for leaks due to weathering or aging in the normal maintenance

routine may be applicable for earthquake damage repairs. This study will conduct a

survey of all existing repair methods for pipeline damages. They will be analyzed and

synthesized on a comparative basis of their seismic resistant performance, availability,

d:ujnr91.rrr 140
simplicity of operation, durability, and cost.

The retrofitting of existing lines for seismic resistance is urgent needed in seismic zones. However, the replacement of existing water or sewer pipelines is very expensive, if not

impossible. The difficulty lies in the facts that a) most water and sewer lines are buried

under congested streets and b) many lines are in need of retrofitting. The opening of a

street for repair at an isolated location is very difficult and expensive, the opening of all streets for replacing all existing lines at one time is out of the question. At this time, no

effective systematic retrofitting method has been developed. Guidelines for small utilities to retrofit their existing facilities do not exist. Two types of retrofit issues need to be

considered: a) low-cost modifications that would be applied by a utility for its everyday

maintenance program and b) moderate cost retrofit projects as permanent solutions.

OBJECT and SCOPE

The overall objective of this project is to provide an effective repairs guidance and

rehabilitation strategy for seismic resistance of buried lifelines.

The scope of this paper covers, but is not limited to, the following items:

• Assessment of Pipeline damage behavior

Assessment of available methods for inspection/detection of damaged

water and sewer pipelines

• Assessment of available methods for repair and restoration of damaged

pipelines

• Assessment of available methods for retrofitting/strengthening of vulnerable

existing systems

Testing and evaluation of currently available and/or newly developed pipe

joints, bends and junction for repair and retrofit purposes

• Developing repair/rehabilitation guidelines and strategies

These tasks will be studied in detail during the course of the investigation. Some

preliminary findings are given below:

ASSESSMENT OF PIPELINE DAMAGE BEHAVIOR

In order to develop effective repair/retrofit methodologies for buried pipelines against

earthquakes, one must understand the seismic damage behavior of these pipelines. The

types of damage of buried pipelines (water and sewer) from past experiences in the

United States[2, 3, 5], Japan[4] and other parts of the world[1 ,5] can be summarized as

follows.

a) Pipeline as a whole b) Pipe Body

.Waving of center line .Circumferential cracks

.Uplift .Longitudinal cracks

d:ujnr91.rrr

141
.Settlement

.Buckling (beam or shell)

.Breaking of pipe body

.Soil deposit into pipe

c) Joint/Junction

.Shear break

.Bending opening

.Pulling off wall

.Rubber ring displacement

.Mortar seal breaking away

.Loosening and leakage

d) Manhole (Sewer)

.Breakage of top cup

.Breakage of inclined wall, vertical

and base wall

.Breakage of mortar joint

.Breakage of pipe connection

.Breakage at intersection

With the experiences learned from earthquakes from the United States, Japan and China,

the following general conclusions can be made.

Rigid joints (such as lead caulked joints) failed more than flexible joints (such as

rubber gasket joints)

With ordinary push-on rubber gasket joints, the joint is weaker than the pipe

body itself with respect to longitudinal ground motions.

• Pipe failed more in weaker soil.

• More failures occurred at the connection between manhole or heavy structure

and pipe.

Notice that the damage behavior of buried pipelines listed above may be caused by the

seismic shaking, large fault movements/ground displacements, soil liquefactions, internal

pressure or combination (old pipelines are affected by erosion also). Thus, the

repair/rehabilitation of buried pipelines should consider both external (ground/soil)

environments and the internal (pipe body/joints or junctions) design parameters of the

pipelines.

One should also note that damage to sewer pipelines may continue to appear for several

years after the earthquake because the initiation of cracks due to an earthquake may not

have been or can not be detected immediately after the earthquake. The assessment of

the effectiveness of current methods of inspection/detection of damage of buried

pipelines, particularly sewer lines will be an important task.

In order to develop effective repair methods and rehabilitation strategies this task is to

conduct a thorough survey and analysis of existing methods for inspection/detection,

repairs/restoration and retrofitting/strengthening of buried pipelines, including those from

the United States, Japan and perhaps other countries when possible.

Inspection/Detection of Damage

ASSESSMENT OF INSPECTION/DETECTION AND

REPAIR/RESTORATION METHODS

diuJnrSl.rrr 142
In general, inspection and detection of damage may be done in two ways. The first step

is an emergency survey/quick inspection for the purposes of quick repair. Then, a

thorough damage survey and inspection is needed for systematic restoration of the

system. Please note that the damage of water system is easily recognizable because of

water flow and pressure drops. However, the survey and inspection of damages of sewer

pipeline/manhole need special tools and are laborious. !t is important to prepare in advance for the possible types of damage caused by an earthquake.

Following discussions apply mainly to sewer systems, while some to water systems.

Check Points for Emergency Survey/Quick Inspection

The purpose of the emergency survey/quick inspection is to prevent the propagation of

a minor damage to a major disaster. The main effort is to limit the effect of the damaged

component to the surrounding facilities. The emergency survey/inspection should include

main lines, distribution lines, and treatment and disposal plants. Check points for

emergency survey/quick inspection are suggested as follows:

.Whether there are unusual or abnormal sign of operations in the

pumping stations and/or disposal facilities;

.Whether there are unusual phenomena in manholes and the surrounding

area of the pipeline;

.Whether there are leaks from water pipelines or from water storage tanks;

.Whether there are inflows of dangerous materia! (gas, oil, sandy

soil, etc.) into the conduits or manholes;

.Whether there are damages of conduits, manholes, etc.; .Whether there is any deterioration of pumping capability;

.Whether there is any outflow of sewerage from the manhole.

l\/lethods of Emergency Survey/Quick Inspection

The emergency survey/quick inspection is to obtain information for the purpose of quick

repair and restoration of the system.

One method of the emergency survey/inspection is by sight and the other is by

instrument. It is also important to observe and record the road condition, manhole

condition, and their surrounding environments which may show signs of damage of water

or sewer systems. It is also important to inspect the treatment plants and pumping

stations. For emergency survey, it is very important to keep a record of inspection

supplemented with photography. Sometimes, it is useful to use a helicopter for a quick

sun/ey.

Methods of Thorough Survey for Complete Restoration

The damage survey should include inspection of cracks (width, length and depth) of pipe

body, damage to joints (breakage or separation), misalignment of pipe axis (vertical and

d:u]nr91.rrr 143
horizontal) and settlement or floating of pipeline or manholes.

The thorough survey/inspection method for buried pipelines can be classified into two

types, namely: direct and indirect methods. When possible, it is desirable to use the

direct method to find out the exact location and intensity of the damage. The direct

method is to examine the damage point by eye or by a remote control camera. Some

available direct survey/inspection methods [6] are listed below:

.Actual observation by eye

.Laser beam to check misalignment of pipes (see Figure 1)

.Radar

.Robotics inspection by a video, special water-proof camera, or

rolling TV camera with a motor (See Figure 2)

In general, for larger diameter pipes (greater than 150 cm) and manholes, direct visual

observations and/or direct measurements by various survey instruments will be

preferable. For small diameter-pipes (less than 100 cm), survey by remote control

camera, TV camera and/or video, laser beam etc. would be used for these

survey/inspection methods. Safety precaution should be made to protect the safety of

the workers and instruments during the survey and repair process.

The indirect survey/inspection method is used when the direct method is not available for

some reasons or when it is difficult to assess the damage by the direct method. The

principle of the indirect method is to observe the flow condition by using some type of

instrument. Some of the available indirect survey/inspection method [6] for sewer lines are listed below:

.Smoke test (see Figure 3)

.Added water test for manhole damage

.Air pressure test for pipe and/or joint damage (see Figure 4)

.Stopping water test

.Flow-rate test

.Water quality test

.Relative leakage test

.Infiltration in sewers by pumping water between manholes

In addition, when necessary the cleaning of the pipelines can serve as survey/inspection

of damage. One may note that these tests are to measure the status of leakage.

Unfortunately these tests can not locate exactly the spot of damage or degree of damage.

However, the results can be as a guide to select repair method(s).

ASSESSMENT OF REPAIR & RESTORATION METHODS

Emergency Repair/Restoration Measures

diuJnrSl.rrr 144
During and just after the earthquake, it is difficult sometimes to carry out all emergency

measures because of insufficient manpower and material. Therefore, it is necessary to set the priority of the regions or the tasks that need emergency measures, such as

survey/inspection, repair and restoration. The emergency measures should be carried

out for the areas where urgency needs exist.

When it is decided that emergency repair and restoration should be carried out, the

following measures should be considered according to the intensity or the effects of the

damage.

.Stop leakage from pipes/conduits using repair clamps/sleeves

.Drain excess water or waste water using portable pumps

.Set-up temporary conduits or pipes

.Dredge sand/soil in conduit pipe and/or manholes

.Repair gaps between manholes and roads

.Fence the rupture places on damaged roads

.Set-up signs warning of road settlement and/or ruptures

.Fill sinking holes with sand

.Set-up traffic control for the dangerous regions

The best repair technique is one that puts the system back into proper functioning order

in the shortest amount of time. For emergency repair, it is to stop leakage from

pipes/conduits as quickly as possible. Currently, some known methods (note that some

methods are applicable to sewer pipes only) of repair for leakage are as follows:

• Caulking

• Injection of epoxy

• Sealing

• Grouting chemically

• Rubber band on outside surface of pipe

• Rubber band on inside surface of pipe

• Water stopping flexible joint

•Insertion of a new pipe inside damgaged one

• Others

For this assessment program, a clear and concise questionnaire of repair/maintenance

practices will be developed and be sent to water and sewer utilities in seismic regions in US, China and Japan. The questionnaires for repair and rehabilitation will include

materials/components used, time and labor for installation, strength and durability if available, and cost, etc.

All methods of emergency repair will be analyzed and/or compared on the basis of their

seismic resistance performance, availability, practicability, durability and cost. Some

d:ujnr91.rrr 145
methods of repair can only be applied to some type of pipelines. They will be identified

and classified for easy usage. Advantages or disadvantages of each repair method will be discussed.

Some of these methods are related to the behavioral damage environments such as soil

conditions, ground water level, buried depth or construction methods, comparison of their

functional operations of the repairs will be evaluated.

Permanent Repair and Restoration l\/letliods

The purpose of permanent repair and restoration is to rebuild water and sewer system

to its original form. As to complete or permanent repairs/restorations of damaged

pipelines, some methods are used to repair/restore a damaged pipeline to its original

strength while other methods are used to correct misalignment which is important

particularly to sewer pipelines.

a) Some methods of repair/restoration to its original strength are given

below:

Replacement of damaged pipes with new pipes

Replacement of damaged pipe joint with a new joint/junction

Reuse of old pipes

Adding concrete around damaged pipe

Injection of epoxy

Caulking

Encasement of pipe

Others

b) Some methods of correcting misalignment of sewer pipeline are:

Leveling Techniques

Injection of epoxy

Grouting with cement

Replacement with new pipe

Others

For a complete coverage on various cases, practices in California, Japan and China will be surveyed. Those methods for permanent repair/restoration will be analyzed, and

compared on the basis of their seismic performance, availability at the site, applicability,

durability, simplicity of operation and cost.

REHABILITATION STRATEGY

d:ujnr91.rrr 146
As discussed earlier, the replacement of all existing lines is very expensive, if not

infipossible. Other important facts are that 1) so many uncertainties, such as exact soil

properties, seismic intensities, etc. are involved in a retrofitting project and 2) no effective

retrofitting method has been yet developed. Therefore, the replacement of all existing

buried pipelines is not recommended by most experts in the lifeline earthquake

engineering field.

Old pipelines made-up of cast iron, clay, asbestos or plain concrete material with cementor lead-caulk joints are very brittle and corrosive. They are most vulnerable to seismic

hazards. Criteria or strategies to retrofit or replace them must be developed.

The low-cost retrofitting strategy at the present time is to upgrade the existing system

during routine maintenance or disaster repair works. Following items are to be

considered.

• Replace current brittle pipes with more ductile material pipes

• Replace current rigid joints with more flexible and/or restrained joints

• Replace current pipes that have been weakened by corrosion

• Repair cracks with strong epoxy

Insertion of a new pipe inside the damaged one

For an important project such as a single large pipeline at a critical fault zone, retrofitting,

repair and/or replacement of pipelines may be necessary. Some suggested methods of

strengthening the environment are as follows:

• Add drainage around existing pipes or add anchorage to pipeline

• Inject chemical (or epoxy) or cement into potential soil liquefaction region

• Drive piles at junction between pipeline and interconnected structures

• Density soils surrounding the pipeline

• Install flexible joints/junctions at strategic locations

Insetrion of new pipe inside the damaged one

It is noted that the above suggested rehabilitation methods for seismic resistance of

buried pipeline structures are by no means completed. Further survey from the U.S.,

Japanese and Chinese practices would be necessary.

In this task, it is necessary to perform technical and economic analyses on various

rehabilitation methods in order to determine the cost-effectiveness of a particular method.

The in-depth study on the cost-benefit of new materials including composite materials and

new flexible joints should be conducted. This project also studies the necessity and costbenefit to strengthen the surrounding environment.

d:ujnr91.riT 147
TESTING AND EVALUATION PROGRAM AT EBAA '

Joint resistance characteristic plays a major role in the seismic resistance of buried

pipelines. To mitigate the earthquake damage to buried pipelines, flexibility rather than

stiffness of the pipeline system is most important. Pipelines need to be designed to move

with the ground rather than to resist the ground movement from the earthquake. Flexible

expansion pipe joint system can be effectively used to reduce the risk of pipe failure due

to sudden ground movement during earthquakes as can be seen in Figures 5 to 6.

Currently, conventional joints and seals have not been thoroughly studied for performance

during an earthquake. A further study of empirical data and analysis results would

improve the characterization of stresses and deformations that can occur as a result of

ground shaking, ground distortion at joints, bends, tees, and fittings.

The project will conduct static and dynamic testings of several commonly used

joints/bends/junctions to determine their resistance (strength) and flexibility

(expansion/contraction or rotation capability) characteristics, which are crucial to seismic

performance of buried pipelines.

The project will perform at least but not limited to the following tests and evaluations:

Evaluation of the performance of existing pipe joint systems with reference

to pull-out (axial expansion and contraction) capabilities.

Evaluation of the performance of existing pipe joint systems with reference

to angular deflection and rotation.

Evaluation of the performance of devices used to prevent pull-out.

Categorization and cataloging of existing joint systems by type according

to pull-out, restraint, and deflection performance.

Development and recommendation of a classification system tying

cataloged joint types to seismicity zones or known seismic hazard levels.

Recommendations for areas of improved seismic design for pipe joints and

fittings.

Retrofit solutions for areas of existing lifeline seismic problems as pertains

to pipe joints, valves, and fittings.

Similar to a Japanese work [7], a classification of joints for seismic resistance will be

developed. The seismic resistant classification of joints/junctions extended from the

Japanese work will consist of three criteria, namely flexibility (extension/contraction or

rotational angle), strength (maximum axial force or bending movement resistant) and

energy dissipation capabilities. EBAA Iron Co. program (an industrial

participation/contribution) will provide the flexibility and strength while ODU program

described below provide energy dissipation information of some commonly used

d:ujnrd1.rrr 148
joints/junctions in the United States.

To create a statistical data base, each test will be repeated at least three times. Three

different commonly used diameters (i.e. 6", 12" and 18") of pipe joints will be tested in

order to establish the performance correlation with respect to the size of the pipe.

TESTING PROGRAM AT ODU

This task is the extension of EBAA's task to evaluate and test the same pipe joints by

cyclic and dynamic loads. The main objective of this part is to compare the static and

dynamic resistant characteristics of these pipe joints and to study their energy absorption

capabilities. The investigators have conducted a valuable investigation [8] on "Energy

Dissipation and Resistant Characteristics of a Flexible Joint" (Figure 7). The tests have

been performed at Old Dominion University using its MTS Dynamic Testing Machine.

Dynamic stiffness and equivalent damping have been obtained by the semi-empirical

means.

For earthquake engineering applications, the hysteretic characteristics of pipe joints will be tested using the MTS Dynamic Testing System at ODU in order to determine the

energy dissipation capabilities of these joints. Low frequency cyclic loads varying from

0 Hz (static load) to 3 Hz at and increment of 0.5 Hz will be applied. An electronic data

acquisition system will be used to record the load-displacement (load cell - LVDT) curves

(hysteresis curves). The area under the hysteresis, which can be automatically calculated

by the data acquisition system, will be established as a measure of energy dissipation

capacity of the joint.

Experiences from earthquakes in the United States, Japan, and China suggest that new

types of flexible-restrained joints would help improve the seismic performance of

segmented and jointed pipelines by allowing larger displacement and absorption of more

energy during seismic shaking, liquefaction, and fault movement.

Upon completion of the testing programs at EBAA and ODU, joint classification in terms

of seismic resistance will be developed for repair and rehabilitation purposes. The

guidelines to select proper joint/junction will depend on the seismic environment (shaking,

liquefactions, fault movements, etc.), site condition (soil, geology, etc.) and pipe material

used.

SYNTHESIS AND GUIDELINE DEVELOPMENT

Upon the completion of previous tasks effective repair methodologies and effective

retrofitting strategies will be developed. There is no unique solution because of the

variation of conditions about pipes, joints, surrounding environments, seismicities etc. Nevertheless guidelines for effective repairs and rehabilitation strategies should be

provided to utilities in order to reduce economical losses due to disastrous earthquakes.

d:u|nr91.rrT

149
Development of Repair Guidelines

The project is to cover nearly all the methods of repair for buried water and sewer

pipelines along with their economical, and technical information on these methods.

Specifically the technical information about the seismic performance of joints, bends,

junctions and other items related to repair and/or retrofit of buried water/sewer pipelines

will be analyzed and synthesized.

The comparison would be based on several indicators, namely: a) seismic performance,

b) cost of installation, c) time required to complete the repair, d) labor/man-power needed,

e) durability, f) availability, g) expected life, h) environmental impact, and i) other factors.

It is expected that upon the completion of the task, clear and concise guidelines for

selecting repair methods under various conditions will be established and simple but

cost-effective repair method(s) will be recommended for future practice.

Development of Rehabilitation Strategies

Effective permanent repairs can be considered as acceptable rehabilitation means.

However, rehabilitation of buried lifelines needs more than just repairs of damage. To

develop effective strategies for a rehabilitation program, one needs to know the whole

field of lifeline earthquake engineering, the damage history and economical loss due to

the disastrous earthquakes, the limitations of the repair/retrofit methods, the damage

survey and inspection techniques, the current operation and monitoring system etc.

One simple example is that old cast-iron pipelines built before 1930 may be too corroded

or with insufficient service capacity to be considered for retrofitting. It may be more

cost-effective to plan a new line instead of retrofitting the old network. Some other

measures must be prepared before the new line is completed. Another example is that

a relatively sound transmission line located in a region previously thought with low

seismicity may be required to be retrofitted because of the consequence of potential

disasters.

Listed previously are several low-cost retrofitting plans by replacing older brittle pipes with

newer ductile pipes, older brittle joints with newer flexible joints etc. during normal

maintenance routines. However, locations have higher seismic risks must not wait too

long to retrofit the entire system because a disastrous earthquake may come at anytime

and lifeline losses and consequence could be substantial. Effective retrofitting strategies

must be developed and actions must begin right away. The development of effective

rehabilitation program will include at least the following schemes:

a) Scheme for inspection and identification of weak components

b) Scheme for evaluation of the effects of the damage to system performance

d:ujnr91.rrr 150
c) Scheme for economic evaluation of the cost of upgrading/replacement of

weak components or adding parallel, redundant pipelines, where applicable

d) Scheme for setting priorities for upgrading/replacement of weak

components

This task of the project develops the procedures and guidelines on each of the schemes

indicated above. The effective strategy would be to combine the normal maintenance

along with committed rehabilitation funds to upgrade the entire system in shortest possible

time. In this task, the guidelines to determine the period of time to complete the

rehabilitation program will be established.

The effective repair methods will be used for rehabilitation purposes. Unless pipe material

is deteriorated, upgrading of the system at strategic locations may only be necessary.

SUMMARY AND CONCLUSIONS

This paper describes an on-going research project on "Repair and Rehabilitation of

Buried Water and Sewer Lifelines" at Old Dominion University, supported by the National

Science Foundation supplemented by an industrial firm, EBAA Iron Inc. of Eastland,

Texas has contributed to the project with their internal funds to conduct the static testing

program on commonly used and newly developed pipe joints at their facilities and in-kind

services to carry out other tasks of the project.

The project consists of three major tasks. The first task is conduct surveys and

assessments of pipeline damage behavior, inspection/detection techniques, emergency

repair/restoration measures and permanent/complete repair/restoration methods from

practices in U.S., Japan and China. The aim of this task is primarily for repair/restoration

of damaged pipelines.

The second major effort will concentrate on the testing of commonly used and newly

developed pipe joints. The testing will include both static and dynamic behavior with

reference to pull-out and angular/rotation capabilities, energy dissipation and

resistant/restraint characteristics. It is to develop a classification system tying cataloged

joint types to seismic zones. The aim of this task would be to search for proper pipe

joints/fittings that will be suitable for retrofitting/strengthening existing

vulnerable/deteriorated pipelines, repairing/restoring damaged pipelines and

designing/constnjcting new pipelines against earthquake hazards.

The third major task would be to develop repair guidelines and rehabilitation strategy.

Synthesis and analysis pipeline damage behavior, current repair practices, strength and

flexibility of commonly used and newly developed pipe joints fitting along with other

technical and economic considerations will be performed. Ranking of various method

against various seismic condition (seismic shaking, large faulty displacement, liquefaction

d:u]nr91.rrr 151
etc) will be established.

ACKNOWLEDGEMENTS

The authors wishes to thank the National Science Foundation in which Dr. Henry

Lagario is the Program Director and EBAA Iron, Inc. in which Mr. Earl Bradley is the

President for this financial and technical support.

REFERENCES

1. G.M. Lee, "The 1985 Mexico Earthquakes: Effects on Water Supply Systems" The

Mexico Earthquake 1985-Factor Involved and Lessons Learned, ASCE, 1987.

pp.364-367

2. L.R.L. Wang, "A New Look Into the Performance of Water Lifeline Systems From

Whittier Narrows, California Earthquake of October 1, 1987," Tech. Report ODU

LEE-05, Department of Civil Engineering, Old Dominion University, January 1990.

3. L. Benuska, et al., "Lifelines-Loma Prieta Earthquake Reconnaissance Report",

Supplement to Vol. 6, EERI, may 1990, pp.239-338.

4. R. Isoyama, and T. Katayama, "Seismic Performance Evaluation of Water Supply

Systems," Proceedings of the Review Meeting of US—Japan Cooperative Research

on Seismic Risk and Lifelines, January 1981, pp. 173-205.

5. L.R.L. Wang, S.P. Sun and S.J. Shen, "Seismic Damage Behavior of Buried Lifeline

Systems During Recent Severe Earthquake in U.S., China and Other Countries,"

Tech. Report ODU-LEE-02, Department of Civil Engineering, Old Dominion

University, December 1985.

6. S. Okamoto, "Manual for Repair Methods or Civil Engineering Structures Damaged

by Earthquakes" (Dec. 1986 in Japanese) English version by NCEER, May 1988.

7. Kubota Ltd., "Earthquake-Proof Design of Buried Pipelines", Pipe Research

Laboratory, Kubota Ltd. 1981.

8. I. Ishibashi, L.R.L. Wang and H. Kennedy, "Energy Dissipation and Resistant

Characteristics of A Flexible Joint," PVP-Vol. 162, Earthquake Behavior of Buried

Pipelines, Storage, Telecommunication and Transportation Facilities, ASME, July

1989, pp. 111-119.

d:ujnrd1.rrr 152
Recorder

Fig.1 Checking Misalignment of Pipes

by Laser Beam

Power Generator TV Monitor ^ ^ '

\b

t 'iww^r' V

VJ3WL

TV Camera

Fig. 2 Inspection of Pipeline Damage

by Remote TV Camera

Air Blower

0 ;

Smoke

Source Breakage,,

Air Plug Air Plug

Fig.3 Smoke Test for Breakage of Pipe

Compressor

Control Panel

Compressor

Air Pressure

Air Plug Air Plug

Fig.4 Leakage Test for Pipe and Joint by Air Pressure

d:ujnrd1.rrr 153
- 260 FECT

Fig.5 Pipeline with Flexible Joints in a Liquefaction Zone

Fig. 6 Flexible Joint for Pipe-Structure Connection

H-EX-TEND

R-EXIBLE EXPANSION JOINfT

STANDARD UNIT HAS 4 INCHES OF EXPANSION AND CONTRACTION

CAPABIUTY (MORE EXPANSION AND CONTRACTION

Fig. 7 A Flexible Joint Cross Section

d:u]nrd1.rrr 154
INVESTIGATIONS ON EXTERNAL FORCE EVALUATION IN SEISMIC DEFORMATION METHOD

Naoki Takahashi , Mikio Takeuchi and Kunihiko Irokawa

Okumura Corporation

ABSTRACT

Investigations were made on the methods for evaluation of the

external forces acting along the transverse direction of the

structures in the seismic deformation method. Assuming rectangular cross-sections for the structures and uniform ground properties, two-dimensional FEM dynamic analysis was first implemented

using the rigidity, mass and depth of the structures as parameters to ascertain the characteristics of external forces acting

on the structures. Investigations were then made on the appropriate values for the external forces along the transverse direction for use in the seismic deformation method using the results

of the two-dimensional FEM dynamic analysis as the norm. The

results of these investigations may be summarized as follows.

1) The bending moment generated by the dynamic shear force acting

on the external faces of the structure accounts for over 50% of

the total bending moment.

2) The inertia force of the structure has little effect on the

generated bending moment .

3) The calculation results in the seismic deformation method will

agree fairly closely with the dynamic FEM analysis results, so

long as the dynamic earth pressure acting on the side walls of

the structure and the dynamic shear forces on the external faces

of the structure are taken into account and the ground spring

constants were evaluated appropriately.

I NTRODUCT I ON

Investigations on the longitudinal forces on structures occupy

the central role in seismic design of underground structures such

as the lifelines and detailed investigations are not usually made

on transverse forces. The increasing depths and cross-sections of

underground structures in recent years accompanying the increasing intensity of land use, however, have given rise to a need to

review the conventional methods for seismic design.

The investigations reported here were made with the purpose of

establishing a method for evaluation of the external forces that

should be made to act in the transverse direction in the seismic

deformation method, the method most widely used in the seismic

design of underground structures. The procedure adopted in the

155
investigations was as follows.

1) The structures were assumed to have recteingular cross-sections

and the ground properties assumed to be uniform. Two-dimensional

FEM dynamic analysis was implemented using the rigidity, mass and

depth of the structures as parameters for obtaining the vibration

characteristics of the structures and the characteristics of the

external forces acting on the structures

2) Responses of the structures were calculated for various structural models and external forces acting on them by the seismic

deformation method. The ground spring constant for the seismic

deformation method is calculated from the relationship between

the static external forces in the two-dimensional FEM and the

ground displacement.

3) Comparison was made between the calculation results in the

seismic deformation method and the FEM analysis results and

considerations made on the appropriate external forces that

should be made to act on the structures in the seismic deformation method.

CONDITIONS OF INVESTIGATIONS

(1) Analysis Conditions for FEM Dynamic Analysis

Large dyncimic earth pressure will act on the sides of the structure , if its rigidity and mass are significantly different from

those of the ground. If the deformation characteristics and mass

of the structure are the same as those of the surrounding ground,

the structure will show the same behaviour as the ground and the

dynamic earth pressure acting on the walls of the structure will

be minimal. In view of this, the analysis here was carried out by

first establishing the two standard models of the "ecpiivalent

rigidity structure" and "equivalent mass structure." As shown in

Fig.l, the equivalent rigidity structure is defined as that in

which the displacement 6a of the top of the structure when a load

whose value per unit width is P is applied to the top of a rigid

frame (height: H, width: L) simply supported at its base, equals

the displacement under a similar load at the top of the ground

element with the same volume as that of the soil removed to

accommodate it. The equivalent mass structure, on the other hand,

is defined as the structure with the same mass as that of the

soil removed to accommodate it. The equivalent rigidity and mass

are termed "G" and "M" in this report. The analysis model, physical properties of the ground and cross-sectional performance of

the structure, and ajialysis cases are shown in Fig. 2, Table 1

and Table 2, respectively.

In the analysis model, the ground as uniform elastic ground with

a rigid base was represented by plane strain elements, while the

structure was represented by beam elements with 15 m square

cross-sections. For the boundary conditions, the base of the

model was made fixed, while the sides were supported by horizontal rollers. The analysis was conducted on one half of the symmetrical model. The standard model in the analysis cases had

equivalent rigidity and mass and a depth of 15 m. The input waves

156
Fig. 2 Finite Element Idealization of Cross-Section for Numerical Analysis

Table 1 Material Properties (Ground and Structure)

Shear wave veloci ty Vs (m/sec) 2 0 0 . 0

Shear modulus G (tf/rrf) 6 5 3 0 . 0 GROUND Poisson' s ratio V 0 . 4 5

Dumping constant h 0 . 0 5

Uni t wei ght 7 af/m) 1 . 6 0

Sectional area A (m) 1 . 2 0 STRUCTURE

Young' s modulus E* '(tf/m') 9. 313 X 10'

Moment of inertia of a cross-section I 0 . 1 4 4

Damping constant h 0 . 0 5

Unit we i gh

7

• ^(tf/m') 4 . 6 0

Note. H ; equivalent rigidity (G) . *2 ; equi valent mass (M)

Table 2 Parameters of Numerical Models

Rigidi ty 0. 01 * G 0. 1 * G 1. * G 10. * G 100. * G

Mass 0. OOOltM 0. 1 * M 1. *M 2. * M 3. * M

Depth 0. 0 m -15, 0 m

Note. G; equivalent rigidity , M; equivalent mass

157
were 20 sinusoidal waves (maxinium acceleration amplitude: 100

gal) with a primary natural frequency (eigen value analysis

result: 1 Hz) which is the prevalent mode in the ground.

(2) Calculation Conditions for Seismic Deformation Method

As shown in Fig. 3, the ground structure system was replaced by a

plane skeleton structural model, with the structure being represented by becim elements and the ground by springs. The analysis

cases are shown in Table 3.

Although the results obtained by the seismic deformation method

are affected by the ground spring constants, there is at present

no standard method for evaluation of the ground spring. In the

investigations reported here, a uniformly distributed load was

applied to the width which is equivalent to the width of each

sides of the structure, using a FEM model of the ground system

and the ground spring constant was calculated from the relationship between the load and displacement as shown in Fig. 4. The

distribution of the normal spring along the side walls of the

structure, and the shear spring along the walls is shown in Fig.

5. Average values for each face, however, were used in the calculations here because of the possibility of effects from the

accuracy of element divisions and corners. The ground spring

values used are listed in Table 4.

The external forces acting on the structure and the methods for

calculating them were as follows.

(a) External Force due to Response Displacement of Free Field

As shown in Fig. 6(a), this external force is obtained by multiplying the displacement of the free field applied to the structure by the ground spring (normal and shear spring). The displacement here is the relative displacement of the free field in

relation to the base of the structure .

(b) Dynamic Shear Force around Structure

As shown in Fig. 6(b), this seismic load is obtained by multiplying the dynamic shear stress of the free field at the depths at

which the members of the structure are located by the unit surface area of each member .

(c) Inertia Force of Structure

As shown in Fig. 6(c), this seismic load is obtained by multiplying the mass of each member of the structure by the horizontal

acceleration of the free field at the depths at which each member

is located . The values for the external forces calculated according to the

procedures described above are given in Table 5.

ANALYSIS RESULTS

(1) FEM Dynamic Analysis Results

(a) Variation in Rigidity of Structure (Equivalent Mass Structure)

158
Kv Kv Kv l^v K\i

Kv -m,

K T Y I » Vi

Kv -WV\}

K V V » T Vi

Kv -m>r

Ks^

Kv Ks^

Ks^ .^Ks^Ks^Ks^Ko^Ks^Ks

Ocafii (.'Icmcnl.

-g/VYKv ^W-Kv

^VV^ Kv

Ks'i K; Ks T Ks 1 Ks 1 Ks T T

^

WV-Kv Kv ; Normal Spring Constant

Ks ; Shear Spring Constant

KvKvKvKvKvKv

Fig. 3 Calculation Model (Seismic Deformation Method)

Table 3 Calculation Cases in Seismic

Deformation Method

Rigidi ty 0. 1*G 1. *G 10. *G

Mass 1. *M

Depth 0. 0 m -15.0 m

Finite Element Model Finite Element Model

1

D

;

Deformation

l\ V = Pv,/6hi

= Psi/(5vi

K V

Ks,

6 H i 6 V i Pv,

Ps.

Normal Spring Constant

Shear Spring Constant

Displacement in Horizontal Direction

Displacement in Vertical Direction

Load in Horizontal Direction

Load in Vertical Direction

Fig. 4 Calculation Method for Ground Spring Constant

159
Depth : 15 m Depth : 0 m

Di sir i bu t i on

of K's 2 (xlO=) 1-

2 1 0

Side

5 2 I 0

(xlO^)

'

Cci

Di s tr i bu I i on

of I\v

1 ing

BoUom

1 (xIO')

0 1 2

Side

0~] ^

•3 (xlO')

4

•5

45

Di sir i but i on

of Ks

(X 10')

i 0

Cei

Side

2 \ 0

(xio')

'

Di sir i but i on

of Kv

1 ng (X 10') 0 1

Side

Bot torn

0 i 5

1 (xio') 2

3

Kv ; Normal Spring Constant

Ks ; Shear Spring Constant

Fig. 5 Ground Spring Distribution (tf/m^)

Table 4 Coefficient of Ground Spring (tf/m^)

Depth Bottom Side Cei 1 ing

Normal spring constant

0 m 1853 664

15 m 2897 994 1009

Shear spring constant

0 m 1090 641

15 m 13C3 1224 861

160
(a) External Force due to Response

Displacement of Free Field

(b) Dynamic Shear Force around Structure

f c f c

P = Ks X (5, Q 1 = Kv X (5 i Kv ; Normal Spring Constant

Ks ; Shear Spring Constant

(5 i = u U b U I

U b

r b

r s

m 1

a b

f c

f b (c) Inertia Force of Structure

Fig. 6 External Force in Seismic Deformation Method

Response Displacement of Free Field in Horizontal Direction

Response Displacement of Free Field in Horizontal Direction

on Bottom of Structure

Relative Displacement on Ceiling

of Structure

Dynamic Shear Stress of Free Field

on Cei 1 ing

Dynamic Shear Stress of Free Field

on Bottom

Averaged r c and r b rs=( rc + V b ) / 2

Inertia Force of Structure

f 1 = m i X a 1 Response Acceleration of Ground

Mass of Structures Distribution

to each Nodal Point

Response Acceleration of Grounds

of Free Field on Cei 1 ing

Response Acceleration of Grounds

of Free Field on Bottom

Inertia Force of Structure on Ceiling

Inertia Force of Structure on Bottom

Table 5 External Forces in Seismic Deformation Method

0 m 15 ra

Exlcrnal Force due to Response OispUcemcnt

of Free Field

Side 180 C56

Ceiling 1057

Dynamic Shear Force around Structure

Bottom 383 742

Side 190 582

Cei ling 427

Inertia Force of Structure 378 297

161
The deformation of the structure at a depth of 15 m is shown in

Fig. 7. Shown in Fig. 8 are the vertical response displacement

distribution along the side walls of the structure, distribution

of the relative displacement in relation to the free field and

distribution of the lateral dynamic earth pressure (normal stress

of the ground element in contact with the right-hand wall of

structure)

.

It can be seen from Fig. 7 that the structure shows a similar

behaviour to the ground. While the structure shows rotational

displacement as a rigid body when the rigidity of the structure

exceeds that of equivalent rigidity, shear and bending deformation prevails in the behaviour when it is smaller than the equivalent rigidity. Fig. 8 shows that the direction in which the

dynamic earth pressure acts on the side walls of the structure is

reversed at a certain point as the depth increases and at the

equivalent rigidity as the rigidity increases.

The above indicates that the dynamic earth pressure acting on

side walls of the structure is closely associated with the relative displacement between the structure and the free field and,

when the rigidity of the structure is greater than the equivalent

rigidity, this tends to result in increased displacement of the

structure, while rigidity smaller than the equivalent rigidity

will tend to reduce the deformation of the structure. This may be

interpreted as meaning that the kinds of external forces that

would encourage the structure to follow the displacement of the

free field are found acting on the structure.

(b) Variation in Mass of Structure( Equivalent Rigidity Structure)

Shown in Fig. 9 are the vertical response displacement distribution along the side walls of a 15 m deep structure, distribution

of the relative displacement in relation to the free field and

distribution of the lateral dynamic earth pressure (normal stress

of the ground element in contact with the right-hand wall of

structure). Unlike in (a) above, there is no vertical variation

here in the deformation amplitude characteristics and the variation in the parallel movement only is shown.

(c) Variation in Depth of Structure

The values corresponding to those shown in Fig. 8 and 9 for when

the depth of the structure was altered to 0 m are given in Fig.

10 and 11. The response characteristics are basically the same at

0 m as at 15 m. The greater response acceleration of the structure at 0 m, however, means that the variation in the response

with the variation in the mass of the structure cannot be neglected.

(d) Dynamic Shear Force on External Faces of Structure

The distribution of the dynamic shear stress acting on the external faces of the structure when the 15 m deep equivalent mass

structure was given varying rigidities is shown in Fig. 12, and

the dynamic shear forces discretely integrated along the top,

side and bottom faces of the structure are shown in Fig. 13

according to parameters concerned.

The dyncimic shear force acting on the external faces of the

structure increases with the rigidity. This is for the Scime

162
Response Displacement

Or Aw u. 01 fu 0. iTLi AL—

i

1. 0+G n in n+n o 100. 0+G

Transition of Deformation

Pattern with Change in Rigidity of Structure

(Depth : 15 in)

80. -60. To (cm)

-40. -20. 0. 20. 40. 60. 80. 10 20 30

'

Fig. 8 Transition of Distribution Patterns of Response

Displacement and Dynamic Earth Pressure Acting

on Side Walls of Structure with Change in Rigidity

of structure (Depth : 15 ra)

Response Displacement

0. GOOHM O 0. m

o l.OtM A 2. 0+M

3.0tM

Relative Displacement

i

-5. 0-2.5 '-ti:0 2.' 5 b.O (cm) Dynamic Earth Pressure

Tension

Coripression

-5

Fig

-40. -20. 0. 20. 40.

115 3?) To (cm) (tf/m^) 9 Transition of Distribution Patterns of Response

Displacement and Dynamic Earth Pressure Acting

on Side Walls of Structure with Change in Bulk

Specific Gravity of Structure (Depth : 15 m)

163
Response Displacement ^———-^nRelative Displacement

-5'

Fig. 10

(tf/m^)

40

r

11

J f. /

I'/

-5. 0 -2.5 (i:irr5~5:o

(cm)

Dynamic Earth Pressure

-3C20. -10." O: 10. 20. (tf/mM

30.

1!^ 0. HG

o 1.0»G A lO.OtG

10 20 30 40 (cm) Transition of Distribution Patterns of Response

Displacement and Dynamic Earth Pressure Acting

on Side Walls of Structure with Change in Rigidity

of structure (Depth : 0 in)

(tf/m^) — 0. HG

••••• 1.0+G — 10. OtG o Free Field

Fig. 12

Response Displacement

Or

Relative Displacement

Difference in Distribution

Patterns of Dynamic Shear

Stress around Structure

according to Changes in Rigidity of Structure

(tf) 1000

5,in

(cm) Dynamic Earth Pressure

-30. -20 10. 0, TCT

(tf/m^) o : 0. HM

A : 1.0»M

; 2.0m

0. ItG l.OtC 10. OtG

Rigidi ty of Structure

100. 0*G

Fig. 11

10 20 30 40 (cm) Transition of Distribution Patterns of Response

Displacement and Dynamic Earth Pressure Acting

on Side Walls of Structure with Change in Bult( Specific Gravity of Structure (Depth : 0 m)

Fig. 13 Relationship between Rigidity

of Structure and Dynamic Shear Force around Structure

164
reason as why the dynamic earth pressure acting on the side walls

varies with the rigidity. As the rigidity increases, the deformation of the structure becomes smaller than that of the surrounding ground and the external forces will move in the direction of

encouraging deformation in the structure.

(e) Bending Moment Generated in Structure

The bending moments generated on the top and side faces of the

structure are shown in Fig. 14. As with the behavioural characteristics of the structure, the variation is greater with the

variation in rigidity than with that in mass. The variation due

to variation in mass, however, is greater at smaller depths.

(2) Comparison of Seismic Deformation Method Calculation Results

and FEM Analysis Results

(a) Deformation of Structure

Comparison is made in Fig. 15 between the relative displacement

of the side walls of the structure and the free field as obtained

by the seismic deformation method and FEM dynamic analysis. When

the rigidity of the structure is smaller than the equivalent

rigidity, shear deformation and bending deformation predominates

in the structure, while with greater rigidity than the equivalent

rigidity, the structure will show a rotational behaviour. These

response characteristics are the same as those obtained by FEM

dynamic analysis and Fig. 15 also indicates the close agreement

between the seismic deformation method calculation results and

the FEM d3mamic analysis results.

(b) Bending Moment Generated in Structure

Comparison is made in Fig. 16 between the bending moment on the

top and side faces of the structure as obtained by the seismic

deformation method and FEM dynamic analysis. The ratios of the

bending moments under each external force obtained by seismic

deformation method calculations to those obtained by FEM dynamic

analysis are shown in Fig. 17. The following conclusions may be

drawn from these f ig.

1) Although the seismic deformation method calculations depend on

the evaluation of the ground spring constants, the results obtained are generally close to those obtained by FEM dynamic

analysis, the errors being within around 10%.

2) The bending moment due to dynamic shear forces acting on the

external faces of the structure accounts for as much as 50% of

the total bending moment, indicating the necessity of taking the

dynamic shear force acting on the external faces in seismic

deformation method calculations.

3) While the effect of the inertia force of the structure on the

overall bending moment is generally small, it may account for as

much as 20% in shallow structures and care needs to be taken over

this point in calculations for structures at small depths.

165

6. 4. 2. 0.-2.-4.-6. 3. 2. 1. 0. -l.;2.-3. 6. 4. 2. 0.-2.-4.-6. (xlO^ tf-m) (^10' tf-m) (xlO' tf-m)

O : FEM Analysis : Seismic Deformaliori Method

Fig. 16 Comparison of Distribution Pattern of Bending

Moment with FEM Results

eo

s

External Force due to Response Displacement of Free Field (sides) External Force due to Response Displacement of Free Field (ceiling)

Dynamic Shear Force around Structure (ceiling and bottom)

Dynamic Shear Force around Structure (sides) Inertia Force of Structure

0. UG

1.0+G

10.0+G

FEM analysis

0. HG

1.0*G

lO.OtG

0-0 0. 2 0.4 0. r. 0.

Fig. 17 Proportion of Each External Force in Total

Bending Moment in Structure (Bottom Right Corner

of Structure)

1.0

167
CONCLUSION

Two-dimensional FEM dynamic analysis was carried out using the

rigidity, mass and depth of underground structures as parameters,

for the purpose of investigating the basic transverse dynamic

response characteristics and the results from this were used in

making considerations on the validity of external force evaluation in the seismic deformation method. The following conclusions

were drawn from these investigations.

1) The external forces acting on structures will vary with the

rigidity of the structure in the direction that would encourage

the structure to follow the behaviour of the free field.

2) While the variation in rigidity has a great influence on the

response displacement and bending moment generated in the structure, the effect of the variation in mass is relatively small.

3) In seismic deformation method calculations, the bending moment

due to the dynamic shear forces acting on the external faces of

the structure accounts for over 50% of the total bending moment.

4) The results of seismic deformation myethod calculations will

agree fairly closely with the FEM analysis results so long as the

dynamic earth pressure acting on the side walls of the structure

and the dynamic shear forces on the external faces of the structure are taken in to account.

F»OSTSCRI F»T

The investigations reported here concerned with structures with

square cross-sections in uniform ground. Investigations are being

conducted at present on the validity of external force evaluation

proposed here when applied to structures with horizontal and

vertical sides of differing lengths.

Principal tasks for the future include the following.

1 ) Investigations on methods of calculating the ground spring

constants in the seismic deformation method.

2 ) Investigations on limits of application of seismic deformation

method with change in ground conditions and structure dimensions.

The study reported here was conducted as a part of the Comprehensive Research Project "Cooperative Research in Development of

Seismic Design of Underground Structures".^

REFERENCE

l)Public Works Research Institute, Advanced Construction Technology Centre et al . , "Development of Seismic Design of Underground

Structures, Cooperative Research Report of PWRI",

1990

168
ESTIMATION OF SYSTEM RELIABILIFY FOR LIFELINE STANDARDS

and

EXAMPLE USING THE CITY OF EVERETT, WASHINGTON'S LIFELINES

Donald Ballantyne, P.E., Kennedy/Jenks Consultants

ABSTRACT

A standard to evaluate lifeline system reliability should be an element of a lifeline system

earthquake code. That element is included in a proposed standard being planned by the

National Institute of Standards and Technology, NIST, for water and sewer systems (Ballantyne,

1991a).

Earthquake loss estimates for six types of lifeline systems serving the City of Everett,

Washington, were made for three earthquake scenarios (Ballantyne, 1991b). Lifeline systems

included water, sewer, electric power, natural gas, telephone, and highways/bridges. System

component damage was estimated by earthquake lifeline experts. Post-earthquake system

functionality was appraised. Lifeline system operators evaluated the time to restore the system

to be operable. Secondary losses, resulting from business interruption due to lack of lifeline

service, were estimated.

The Everett study provides an example of the lifeline system evaluation process using current

methodologies and damage estimating data. This paper discusses conclusions about the system

reliability evaluation process that can be drawn from the Everett study. It proposes

recommendations that should be included in the proposed NIST standard, and for future lifeline

research.

INTRODUCTION

A standard to estimate lifeline system reliability should be a key element of seismic code for

lifeline systems. Lifeline system reliability is the key component differentiating lifeline system

standards from building standards. This consideration is of current interest because the United

States Congress has given NIST the charge of developing a plan for the development of

recommended standards for lifeline systems (Dikkers, 1991). One of the considerations in

developing those standards is reaching consensus on an approach to assess post-earthquake

lifeline system reliability.

169
A proposed standards approach should include five elements (Ballantyne, 1991a):

1. Policy Statement

z. oystem i^.vaiuation

3. Component Design/Evaluation

4. Equipment and Material Standards

5. Emergency Planning and Response.

The focus of this paper is on Element 2, System Evaluation.

"Earthquake Loss Estimation of the City of Everett, Washington's Lifelines," the Everett study,

provides an example of system evaluation for six types of lifeline systems for three earthquake

events (Ballantyne, 1991b). Lifeline systems included water, sewer, power, natural gas,

telephone, and highways/bridges.

The methodology applied in the Everett study provides an example of what a standard evaluation

procedure could entail. Conclusions and recommendations are presented from consideration of

the Everett study in light of the standards evaluation procedure.

EARTHQUAKE LIFELINE WATER SYSTEM STANDARDS

Five elements of the standard would provide a rational step-by-step approach to water system

design to reduce earthquake imparted disfunction. Element 1, Policy Statement, would define

expected levels of system operability. Element 2, System Evaluation, would provide a procedure to assess earthquake performance and resulting post-earthquake system operability.

Element 3, Component Design/Evaluation, and Element 4, Material and Equipment Standards,

which already exist for many water system components, would define procedures and criteria as described by their respective element names. Element 5 is a separate topic, and will not be

discussed in this paper

Policy Statement

The policy statement would define post-earthquake system operating expectations. For example,

for a "design" earthquake, fire protection capability could be required for areas with a real estate density exceeding some given level. Supply for drinking water could be required within three

days, even if it was provided through temporary facilities. Full resumption of service would be

required within seven days.

170
The policy statement would provide guidance on a schedule for meeting the policy requirements.

It would be expected that those schedules would be based on risk. For example, California

facilities would have a shorter time to reach compliance than those in New York State.

System Evaluation

The system evaluation standard would include a procedure and evaluation data to assess the

system's expected performance for comparison against the policy statement. Both facility

component loss estimates and repair times would be included.

For example, application of the standard approach could answer the question, "Will the system

be capable of providing adequate fireflows to given areas following a particular earthquake

event?" Another example would be, "Can the service be restored to a particular residential area within seven days following the defined major earthquake?"

The standard would establish standard component function loss estimating methodologies in the

form of empirical fragility curves, structural calculations, or other approaches. Data from

component design and material and equipment standards would be used when available.

Approaches to establish system functionality using component functionality would be defined.

Techniques to estimate system restoration times would be incoi^rated.

Componeiit Design/Evaluation and, Material and Equipment Standards

Component design/evaluation and material and equipment standards would be used both to design and specify new/replacement facilities as well as conduct detailed assessments of the

vulnerability of existing facilities.

Component design codes are found in such documents as the Uniform Building Code and the

American Water Works Association's DlOO, Standard for Welded Steel Tanks for Water

Storage. Additional standards can be developed where they do not exist, such as seismic

resistant design of pipelines. Examples of material and equipment standards are for pipe, as developed by AWWA, and electrical equipment, as developed by NEMA. They can be

supplemented for seismic considerations where needed.

171
DISCUSSION - SYSTEM EVALUATION ELEMENT

Need for System Evaluation Element

The interaction of system components, should differentiate lifeline earthquake system design

standards from buUding design standards.

System evaluation is not required in building design, as there is no interrelationship between

buildings, new or existing. As new buildings are constructed in accordance with seismic design

codes, the overall vulnerability of real estate is decreased.

Lifeline system vulnerability is not necessarily reduced as new system components are constructed. Most lifeline systems already exist. Many have key components that will last for

many years before replacement would be warranted based on non-seismic performance criteria.

In many cases, such as cast iron pipe in liquefiable areas, those components are highly

vulnerable to earthquake. Some pipe could last, as it has in the past, for centuries without

replacement. In many cases, failure of those components would mean failure of the system as a whole. Therefore, system component earthquake standards may not result in the overall

system achieving the criteria identified in the policy statement. Therefore, a system evaluation

standard should be incorporated in the proposed NIST standard.

Another advantage of the system evaluation approach is its ability to identify systems that are inherentiy weak, at a system level. Simplistic examples would be identification of systems that

had single water sources or transmission lines, on which the entire system depended.

If the system evaluation approach is not incorporated in lifeline standards, there would be a great concern that the vulnerability of lifeline systems could remain high for many years, even though

new/replacement facilities were being designed in accordance with seismic resistant standards.

Intent of System Evaluation Provisions

The intent of a system evaluation element is to require consideration of seismic criteria in water

system planning. Typically, water systems are modified on a continuing basis to:

• Accommodate growth by providing increased water supply

• Replace corroded pipelines with high maintenance requirements and/or reduced

flow capacity

• Replace/upgrade treatment facilities required to meet more stringent water quality

requirements

172
• Replace/upgrade pump stations and storage with high maintenance requirements

or with those that are inefficient to operate.

It is the plan that by taking seismic vulnerability into consideration during the planning process

for the considerations listed above, the additional cost specifically for seismic upgrade would be

minimal.

Several examples of this intent can be provided. First, many water purveyors replace pipelines on a regular basis. The criteria for replacement typically includes maintenance history and flow

reduction from corrosion. Seismic considerations could be added, promoting the replacement

of, for example, cast iron pipe in liquefiable soil areas. Second, assume a water purveyor

delivers all their water through a transmission line passing through a liquefiable area. Because

of increasing demand, the purveyor requires a second transmission line. If earthquake system

evaluation requirements were in place, an option to design a new pipeline sited outside the

liquefiable area, and with a capacity to replace some of the original vulnerable pipeline's

capacity, might be more favorable.

CITY OF EVERETT, WASHINGTON LIFELINES STUDY

Introduction

The Everett lifeline study evaluated system vulnerability and estimated earthquake losses to six

lifelines systems serving the city. Donald Ballantyne was the principal investigator and Bill

Heubach, project engineer (Ballantyne, 1991b).

The City of Everett, with a population of 70,000, is located about 20 miles north of Seattle.

The city is quite self reliant with major employers including Boeing at their 747/767 assembly

plant and a Scott Paper Company mill.

The city is on a peninsula bounded on the west by Possession Sound, a branch of Puget Sound

and on the north and east by the Snohomish River. The area around the Snohomish River and,

to a lesser degree, along Possession Sound is highly liquefiable.

Lifeline Systems

Each of the six systems was studied by lifeline experts who are some of the best in the country

in their respective fields. Each expert worked closely with the respective system owners. The

lifeline systems, owners, and experts are shown in Table 1.

173
Project Methodology

The project proceeded through the following stq)s:

11. Earthquake Hazard Definition

2. System Inventory/Replacement Cost Estimate

3. Data Review/Site Visit v

4. Component Vulnerability Assessment/Loss Estimate

5. System Vulnerability/Functionality Assessment

6. Repair Time Estimate

7. Secondary Loss Estimate.

Earthquake Hazard Defmition

Three post-earthquake events were defined and hazards mapped by C.B. Crouse of Dames &

Moore and are shown in Table 2.

Two of the three earthquakes scenarios were very large, one in 400 years, events resulting in

mapped areas of Modified Mercalli Intensity as high as DC. Liquefaction probability was also

mapped. Earthquake intensity and liquefaction probability was provided to each of the lifeline

experts.

System Inventory, Data Review/Site Visit

Each lifeline expert worked closely with the system owner in developing the system inventory,

estimating direct losses (repair/replacement costs), and gathering design information. Repair

costs were based on repair time estimates for each repair, labor, equipment, and material costs. Replacement costs were based on original construction costs (when available) escalated to current

costs or comparing the costs to other facilities with a known value. Typically, a system owner

representative joined the lifeline expert in site visits.

It should be noted that the study considered the entire water, sewer, and highway/bridge system,

while only the local intertie (substation) and distribution systems were considered for electric

power, telephone, and natural gas. This likely had an affect on the reported results.

174
ComponentVulnerabiUtyAssessment/Ix)ss Estimate, andSystemVulnerabiUty/Functionality

Assessment

Each lifeline expert estimated the extent of damage to each system component based on fragility curves and/or engineering judgement. The extent of damage was estimated for both repair

replacement and functionality. Damage assessment fragility curves and engineering judgement

for each lifeline was based on each lifeline expert's experience in previous studies. In many

cases, it was found that because of the linear nature of the systems that system outage could be

estimated without the use of a system network analysis. The impact on the functionality of each

system was then assessed with input from the system owner. Direct losses (repair/replacement)

for the M8.25 Benioff Interplate Earthquake are shown on Table 3.

Repair Time Estimate

System owners were provided with estimated system component damage from each lifeline

expert. System owners then estimated the time to repair their system based on expected

available resources. Those system outage duration times are shown for the M8.25 Benioff

Interplate Earthquake on Table 3.

One important consideration of the study was that damage information for each system was

provided to all system owners simultaneously, in order for them to account for the impact of

other system disfunction on the repair of their own systems. One example was the impact on

access for repairs limited by bridges being out of service.

Secondary Loss Estimate

Business interruption (secondary) losses were estimated taking into account the gross city

product, outage duration for each particular lifeline, and a economic dependency factor on the

particular lifeline. Secondary losses from fire were not estimated in this project. Those business

interruption losses are shown for the M8.25 Benioff Interplate Earthquake on Table 3.

Everett Study Conclusions

The study showed that business interruption losses were less than direct losses. However, these

results were skewed by the high direct cost of bridge replacement. If bridges are excluded, the

average ratio of business losses to direct losses is approximately 2 to 1. The business/direct loss

ratios for each system are shown for the MS.25 Benioff Interplate Earthquake on Table 3.

175
The loss ratio ranges from (-0. 1) to 76. This extreme range may be the result of several systemspecific considerations. Lifeline systems are inherendy different in their repair costs versus the

cost of losing service. Bridge spans are extremely expensive to repair compared to repairing a pipeline break. Both failures may have the same order of magnitude impact on a business.

The telephone system was evaluated as having extreme differences between the dollar loss and

function loss fragility curves. Other lifelines had curves that more closely matched.

Another reason for the range of business to direct losses may be related to lack of

standardization in loss estimation approaches.

The study shows that direct damage estimates do not adequately represent total losses expected

as a result of earthquake lifeline failure.

CONCLUSIONS AND RECOMMENDATIONS

The Everett study demonstrates that it is feasible, using currentiy available methodologies and

data, to evaluate lifeline system post-earthquake functional reliability. Estimation of functional

reliability is the focus of Element 2, System Evaluation, in the proposed lifeline standard.

In addition to functional reliability, system outage duration, direct losses, as well as secondary,

business interruption, losses can be estimated.

The effect of the interaction of system disfunction can be incorporated into the system

disfunction and outage duration estimates, resulting in a more realistic model.

There is a significant variability among the lifelines evaluated between the estimated magnitude

of direct losses and secondary losses. The inherent differences between different lifeline

system's design and operation may account for some of these differences.

However, the methodologies and data available to develop Element 2, System Evaluation, with an acceptable level of reliability, lags compared to the other proposed standards elements.

Looking beyond the scope of the Everett study, in retrospect, there may be inconsistencies

between the findings of that study and actual earthquakes. Even following the two large

earthquakes scenarios proposed in Everett, system outages were as low as zero hours. There

is some concern, that, for example, compared to the smaller Loma Prieta event, resulting system

disfunction may be more severe for some of the lifelines studied.

Recommendations resulting from the consideration of the Everett study as an example of lifeline

system evaluation are as follows:

• System evaluation should be included as an element in a lifeline earthquake

standard.

176
• Better earthquake damage data from which to enhance fragility curve development

should be developed on a continuing basis. This includes improved methods for

quantification of earthquake hazards.

• A more consistent approach to loss estimation should be developed across the

industry. This can be achieved in the standards development process.

• Better education of the system owners in understanding the effects of earthquakes

on their lifeline systems should be undertaken.

ACKNOWLEDGEMENTS

The author would like to thank the National Institute of Standards and Technology working

through the American Society of Civil Engineers Technical Council on Lifeline Earthquake

Engineering for support in developing the NIST Draft Plan (Ballantyne, 1991a). Appreciation

also goes to the United States Geological Survey for support in conducting the Everett study

under award number 14-08-0001-G1804 (Ballantyne, 1991b).

A special acknowledgement goes to each of the Everett study teams presented in the text,

including both the lifeline experts as well as lifeline system owner representative.

177
REFERENCES

Ballantyne, Donald B., "Draft Plan for the Development of Design & Construction Standards

for Water & Sewer Facilities," draft, to be presented at a NIST Workshop, Denver, CO,

September 25-27, 1991.

Ballantyne, Donald B., Heubach, William. F., "Earthquake Loss Estimation for the City of

Everett, Washington's Lifelines" funded by USGS award number 14-08-0001-G1804,

Kennedy/Jenks/Chilton, Federal Way, WA, May 1991.

Dikkers, Robert D., "Development of Seismic Design Standards for Lifelines" National Institute

of Standards and Technology, presented at the U.S. -Japan Workshop on Earthquake Disaster

Prevention for Lifeline Systems, August 19-21, 1991, Los Angeles, CA.

178
TABLE 1

LIFELINES/OWNERS/LIFELINE EXPERTS

Lifeline Owner

Water City of Everett

Sewer

Electric Power

Telephone

Natural Gas

Highways/Bridges

Lifeline Expert

Donald Ballantyne, Kennedy/Jenks

Donald Ballantyne, Kennedy/Jenks

Dennis Ostrom, S. California Edison

Felix Wong, Weidlinger Associates

Ron Eguchi, Dames & Moore

Stu Werner, Dames & Moore

City of Everett

Snohomish County PUD

GTE

Washington Natural Gas

WASHDOT

TABLE 2

EARTHQUAKE EVENTS

Source Zone

Puget Trough

Benioff Interplate

Benioff Intraplate

Magnitude

6.5

7.0

8.25

Return

Interval(yrs)

403

58

452

Hypocentral

Distancefmi')

7.5

32

46

Focal

Depth (mi)

25

9

179
TABLE 3

EVERETT STUDY RESULTS

Lifeline

Direct

Losses

(million"i

Outage

Duration

fdavs)

Business

Losses

Cmillion")

Business/

Direct

Losses

Water $4.8 6 $44.3 9.2

Sewer 6,2 6 44.3 7.1

Electric Power 0.3 0.1 0.5 1.7

Telephone 31.7 0 (-3.2) (-0.1)

Natural Gas 0.2 2 15.1 76

Highwav/Brid^es 171 7 35.3 \

Total $214.2 $136.3

180
DYNAMIC RESPONSE OF TWIN CIRCULAR TUNNELS

DURING EARTHQUAKES

Toshihiko OKUMURA*, Naonobu TAKEWAKI*, Katsumi SHIMIZU**

and

Kiyoshi FUKUTAKE*

* Ohsaki Research Institute, Shimizu Corporation,

Tokyo, JAPAN

Institute of Technology, Shimizu Corporation,

Tokyo, JAPAN

ABSTRACT

This paper presents the dynamic behavior of twin circular tunnels subjected to the vertically incident SV wave. Using the

two dimensional finite element method, the interaction effects

of the twin tunnels on the response of the lining are evaluated

by comparing the results of the twin-tunnel and single-tunnel

cases. The results show that the shearing force on the adjacent

side of the lining increase due to the interaction between the

two tunnels. The degree of the interaction is sensitive to the

distance of the tunnels and the shear wave velocity of the soil

surrounding the tunnels, although the depth of the tunnels does

not affect the results. However, the interaction effects are

discovered to be negligible when the distance between the two

tunnels is greater than two times the diameter of the tunnel.

INTRODUCTION

Because of the difficulty in obtaining large and continuous

lands for new construction projects in metropolitan areas such

as Tokyo, subterranean spaces will be increasingly utilized in

the near future for the construction of railroads, highways,

etc

.

Under the circumstances, "A Cooperative Research in Development

of Seismic Design of Underground Structures" has been carried

out by Public Research Institute, Advanced Construction Technology Center, and eight other institutions as a part of the Comprehensive Research Project entitled "Technology Research and

Development Regarding Use of Underground Spaces." This study is

a part of the cooperative research mentioned above.

Regarding the seismic resistant design of a tunnel, only the

longitudinal direction has been examined in most cases. Howev181
er, when the size of a tunnel becomes larger, the crosssectional direction should also be examined since the displacement at the top relative to the bottom is greater than that of

small tunnels, resulting in the larger resultant force of the

lining. In addition, the dynamic behavior of twin tunnels has

not been thoroughly studied, although such twin tunnels has been

and will be constructed.

In this study, dynamic response analyses of twin tunnels are

carried out by using the two-diment ional finite element method,

and the dynamic interaction effects of the twin tunnels are examined. The results obtained in this study will provide useful

information in the development of seismic design of underground

structures

.

SCOPE OF THIS STUDY

This study deals with the dynamic behavior of twin circular

tunnels subjected to the vertically incident SV wave. For this

purpose, the two-dimensional finite element method in the

frequency domain is utilized to calculate the shearing force,

axial force, and bending moment of the tunnel lining.

The interaction effect of one tunnel to the other is examined by

comparing the numerical results (transfer functions, response

time histories, and maximum response distribution along the

lining) of the single tunnel with those of the twin tunnels with

various distance, while other parameters such as shear wave

velocity of the ground and depth of the tunnels are fixed.

From the comparison, the location where the interacton effect

appears most noticeably is identified first. Next, the degree

of increase in the shearing force, axial force and bending

moment at these places are evaluated. Then, the relation

between the degree of the interaction effect and the distance of

the two tunnels is developed. The contribution of the shear

wave velocity of the surrounding soil and the depth of the

tunnels to the interaction effect is also studied.

The flow of this study is summarized in FIGURE 1.

ANALYSIS MODEL

FIGURE 2 depicts the summary of the analysis model used in this

study. The finite element models have the viscous boundary at

the bottom and the energy-transmitting boundary on the side to

represent the half-space vertically and laterally. Beam

182
elements are used to model the lining (concrete shield) of the

tunnels.

Throughout this study, the diameter of the tunnels and the

properties of the lining are fixed. The two tunnels are also

assumed to be identical in size, depth and lining.

The following parameters are considered to be variables:

Distance between two tunnels (D): 5m, 10m, 20m and oo (single)

Depth of tunnels (H): 20m, 35m and 50m

Shear wave velocity of soil (Vs): lOOm/s, 200m/s and MOOm/s

RESULTS AND DISCUSSIONS

Transfer Functions

First, the interaction effect of the two tunnels on the bending

moment and axial and shearing forces of the tunnel lining is

examined in the frequency domain.

FIGURES 3> 4 and 5 show the transfer functions of the bending

moment, axial force, and shearing force, respectively, at

several points on the lining of the (right) tunnel, and compares

the results of the single and twin tunnels. These points on the

lining are selected for each figure because the maximum forces

appear at these points when a tunnel is subjected to the

shearing deformation. These results are for the shear wave

velocity of soil = 200m/s, and the depth of the tunnels = 50m.

It is seen in FIGURE 3 that the interaction effets on the

bending moment appear especially on the side adjacent to the

other tunnel. When the distance between the two tunnels is 5m,

the bending moment on this side is approximately 20% larger in

the very low frequency range than that of the single tunnel.

However, the interaction effect is negligible on the farther

side of the tunnel.

In FIGURE the interaction effect on the axial force is not as

remarkable. Even when the distance between the tunnels is 5m,

the increase in the axial force is at most ^0%.

On the contrary, as seen in FIGURE 5, the interaction effect on

the shearing force is clear on the side adjacent to the other

tunnel. When the two tunnels are 5m apart, the shearing force

at 0=-9O° is approximately kO% greater than the single tunnel.

However, the degree of the interaction effect decreases as the

distance between the two tunnels increases. When the distance

is 20m, the result is almost identical to that of the single

tunnel. It should be noted that the ratio of the amplitude of

the twin tunnel to single tunnel is almost identical, at least

in the low frequency range (0 to H Hz).

183
Time Histories of Response

FIGURE 6 compares the time histories of the shearing force at

the two different points (9=-90° and 90°) on the lining when the

N-S component of 19^0 El Centre record is used as the input

earthquake ground motion. In each figure, the solid line

represents the result of the twin tunnel with distance of 5m and

the dotted line corresponds to the single tunnel.

At the point adjacent to the other tunnel (0 = -9O°) , the shearing

force of the twin tunnel is magnified due to the interaction of

the two tunnels. On the other hand, the difference is not

noticeable at 6=90°. The increases in the maximum value of the

time history are 39^ at e=-90° and only 2% at 9=90°.

Maximum Response Distribution

The distributions of maximum response on the lining are drawn in

FIGURE 7 by plotting the maximum value of the time history at

each of the points (every 7.5°) on the lining.

The largest difference appears on the distribution of the

maximum shearing force near 9=-90°. It agrees with the results

shown in FIGURES 5 and 6. The distributions of the maximum

axial and shearing forces of the twin tunnels shift slightly to

the right on the figures. This suggests that the deformation of

the tunnels is slightly slanted.

In order to measure the interaction effect quantitatively, the

interaction coefficient is introduced in this study. The

interaction coefficient is defined as the increase in the peak

value of the maximum response distribution normalized by the

value of single tunnel. In FIGURE 7, the coefficient is

calculated as a/b. The range of the angle in which the

coefficient is evaluated is shaded in the figure. In the case

shown (D = 5m, Vs = 200m/s, and H = 50m), the interaction

coefficients are O.m, 0.08 and O.Ml, respectively, for the

bending moment, axial force and shearing force.

FIGURE 8 compares the distribution of the maximum responses of

the twin tunnels for the different input ground motions. The

solid and dotted lines correspond to the N-S component of 19^0

El Centre record and N-S component of Hachinohe record of 1968

Tokachi-oki earthquake, respectively. Although the Hachinohe

record causes the greater responses, the shapes of the

distribution of responses are quite similar to each other,

meaning that the difference in the frequency contents of input

motion does not affect the degree of interaction. This fact is

also supported by the transfer functions (FIGURES 3 to 5) where

the ratio of twin tunnels to single tunnel is almost constant

throughout the frequency range.

184
Relation between Interaction Effect and Distance

The interaction coefficient which was defined previously is

calculated for various conditions, i.e., the shear wave velocity

Vs= 100, 200 and MOOm/s, and the depth H = 20, 35 and 50m. In

all of the above cases, the distance between the two tunnels D

is changed from 5 to 20m.

The interaction coefficients for the depth 20, 35 and 50m are

shown in FIGURE 9. The shear wave velocity is fixed to 200m/s

in the calculation. This figure clearly shows the way in which

the interaction coefficients decreases as the distance between

the tunnels increases. It is also apparent that the depth of

the tunnels does not affect the degree of interaction.

FIGURE 10 shows the interaction coefficients for Vs = 100, 200

and MOOm/s, where the depth is fixed to 50m. In contrast to

FIGURE 9, the interaction coefficient is found to be very

sensitive to the shear wave velocity of soil surrounding the

tunnels. Given the same tunnel distance, the interaction

coefficient is almost proportional to Vs, e.g., the coefficient

for Vs = MOOm/s is nearly twice as much as that for Vs = 200m/s,

and almost four times that for Vs = lOOm/s. However, even for

the case with Vs = MOOm/s, the interaction effect is negligible

when the distance of the tunnels is 20m, i.e., twice the

diameter of the tunnel.

CONCLUSIONS

In this study, the dynamic interaction effect of twin circular

tunnels subjected to incident SV wave is examined numerically.

Major results derived in this study may be summarized as

follows:

(1) The interaction effect appears most clearly on the shearing

force of the lining on the side adjacent to the other

tunnel. On the contrary, the effect on the axial force is

small

.

(2) The degree of interaction is not sensitive to the frequency

contents of input ground motion.

(3) The degree of interaction decreases exponentially as the

distance between the tunnels increases. The effect is

negligible when the distance is more than two times the

diameter of the tunnel.

(4) The interaction coefficients defined in this study is

almost proportional to the shear wave velocity of the soil

185
when other parameters are fixed. However, the difference

in the depth does not change the coefficient.

FUTURE DIRECTIONS

This study is still on-going. The following subjects are to be

studied in the future so that the results of this study are

reflected in the development of seismic design of underground

structures.

(1) The interaction coefficient may be expressed as a function

of the distance between the tunnels (D), diameter of the

tunnel (d) and shear wave velocity of soil (Vs).

Additional parameter studies will be necessary to develop

the form of the function.

(2) The interaction effect when the twin tunnels are

constructed vertically or diagonally should also be

examined

.

ACKNOWLEDGMENT

This study is carried out as a part of the "Cooperative Research

in Development of Seismic Design of Underground Structure,"

186
2-D FEM

r

Comparison of Results

Transfer Functions

frequency

Time Histories

Relation between Distance

and Interaction Effect

c«

IS

Vs = 400

Vs = 200

Vs=100

distance between tunnels

FIGURE 1 FLOW OF THIS STUDY

Surrounding soil S-wave velocity ( Vs) = 100, 200 and 400 m/s

Unit weight =1.7tf/m^

Poisson's ratio = 0.35

Depth (7f) = 20, 35 and 50 m Distance between

two tunnels (D) = 5, 10,20 m

and single tunnel

Lining (beam elements)

Shear modulus = 9X10^ tf/m^

Unit weight = 2.5tf/m^

Poisson's ratio =0.1667

Thickness = 0.5m

(Viscous Boundary)

FIGURE 2 ANALYSIS MODEL

187
30.0

^ 24.0

O W3 18.0

.5 g 12.0

03 6.0

0.0

0

1 1 Twin(D =

1

= 5m) e

1 = -45° ~ Twin(D == 10m)

Twin(D == 20tn)

.0 2.0 4.0 6.0 8.0 10

30.0

24.0 -

c

1 5,18.0

Frequency (Hz)

30.0 - 24.0

P cd |-|18.0

.5 1 12.0

c

03 6.0

0.0

1 1 Twin(D =1 = 5m) 0 =1 = -135° - Twin(D == 10in)

Twin(D == 20m)

^^^^^

Single

1—>^ .

I Twin(D = 5in) 0 = 45° Twin(D=10m)

Twin(D = 20m)

Single

^Il2.0 h

c

CQ

0.0 2.0 4.0 6.0 8.0

Frequency (Hz)

10.0

30.0

c 24.0

B « Si 18.0

•— o 12.0

C <-> 0) ^

n 6.0

0.0

1 1 i i Twin(D = 5m) 0 = 135°

---- Twin(D=10m) -- Twin(D = 20m)

Single

,0 2.0 4.0 6.0 8.0

Frequency (Hz)

10.0 0.0 2.0 4.0 6.0 8.0

Frequency (Hz)

10.0

FIGURE 3 TRANSFER FUNCTIONS OF BENDING MOMENT

(Vs=200m/s, depth=50m)

1.00

0.80

Twin(D = 5ni) 0 = -45° Twin(D = 10ni)

Twin(D = 20m)

Single

1.00

0.80

fe-SO.60

II 0.40 < ^

0 .0 2.0 4.0 6.0 8.0 10.0

Frequency (Hz)

1.00

0.80

13 0.60

l|o.40

< ^

0.20

0.00

—I r

1 Twin(D = 5m) 0 = -135° Twin(D = 10m)

Twin(D = 20m)

Single

0.00

1 i Twin(D =i 1 = 6m) 0 = 45° - Twin(D == 10m)

Twin(D == 20m)

- Single

0.0 2.0 4.0 6.0 8.0

Frequency (Hz)

10.0

l.GO

0.80 |- Twin(D=10m)

Twin(D = 20in)

Single

T

1 \ Twin(D = 5m) 0 = 135°

0.0 2.0 4.0 6.0 8.0 10.0

Frequency (Hz)

0.0 2.0 4.0 6.0 8.0

Frequency (Hz)

10.0

FIGURE H TRANSFER FUNCTIONS OF AXIAL FORCE

(Vs=200m/s, depth=50m)

188
0.10

-|0.08 —\ \ r r

Twin(D = 5ni) 9 = 0° Twin(D= 10m)

Twin(D = 20m)

Single

0.0

I Twin(D = 5in) 9 = -90° Twin(D = 10m)

Twin(D = 20m)

Single

2.0 4.0 6.0

Frequency (Hz)

0.00

8.0 10.0

0.10

"I 0.08 - 0.06

[S 0.04

I 0.02 ^ 0.00

1 1 Twin(D =1 1

= 5m) 0 = 90° ~ Twin(D == 10m) ^ Twin(D == 20m)

-\ Single

0.0 2.0 4.0 6.0

Frequency (Hz)

0.0 2.0 4.0 6.0 8.0

Frequency (Hz)

10.0

0.00

\ \

i Twin(D = 5m) 9 = 180° Twin(D=10m)

Twin(D = 20m)

Single

0.0 10.

0

2.0 4.0 6.0 8.0

Frequency (Hz)

FIGURE 5 TRANSFER FUNCTIONS OF SHEARING FORCE

(Vs = 200m/s, depth = 50ni)

8 n

Twin(D = 5iti), Max = 6.36, 0= -90°

Single, Max = 4.49

Twin(D = 5ni), Max = 4.43, 9 = 90°

Single, Max = 4.34

:;)o

0123456789 10 CSEC]

FIGURE 6 TIME HISTORIES OF SHEARING FORCE

189
^ 2000

^ 1500

§ 1000

10.0

14-> 7.5

Q>

<JUo

fc- 5.0

be

0 2.5

0)

0.0

1 1 1 1 1 1 1

' Twin(D = 5m) _ Single Bending Moment _

a ^<-\

b / \ / \

Y 1 1 1 180 -90 0 90

Angle 9 (deg.)

n I \ \ \ Twin(D = 5m)

Single Shearing Force

60.0

180

0.0

-180

1 \ 1 \ r

Twin(D = 5m)

Single Axial Force

-90 0 90

Angle 9 (deg.)

0=0'

e=-45'^-^*-^ 9 = 45'

= _9o*i 1/ *e=

0=-135

9 = 180"'

90"

9 = 135°

-180 -90 0 90 180

Angle 9 (deg.)

FIGURE 7 COMPARISON OF DISTRIBUTIONS OF MAXIMUM RESPONSE

(SINGLE AND TWIN TUNNELS)

180

B 2400

1800

CO 0

12.0

I 9.0

6.0

3.0

0.0

180

1 \ 1 \ 1 r

El Centre Bending Moment

Hachinohe

180 -90 0 90

Angle 9 (deg.)

1 \ r—I1 r

El Centro Shearing Force Hachinohe

180

60.0

0.0

1 r

180

El Centro Axial Force Hachinohe

-90 0 90

Angle 9 (deg.)

9=0"

e=_45° ^-J^-v. 9 = 45°

0=-90°/^ 90° |9 =

9=_135°^-~«—'^0 = 135°

9 = 180°

180

180

-90 0 90

Angle 9 (deg.)

FIGURE 8 COMPARISON OF DISTRIBUTIONS OF MAXIMUM RESPONSE

(EL CENTRO AND HACHINOHE RECORDS)

190
0.80

0) g 0.60

0) ^0.40

o

"i 0.20

S 0.00

1 ©-1 —

1 1 H = 50m

A- —A H=35in

X-- -x H = 20m

Bending Moment

1

^0.80

{§0.60

o

«0.20

a> hSo.oo

1 1 o o

1 1 11 = 50m

A A H = 35m

X X H = 20m

Axial Force

0.0 5.0 10.0 15.0 20.0 25.0

Distance between Tunnels (m)

0.0 5.0 10.0 15.0 20.0 25.0

Distance between Tunnels (m)

-0.80

c

0) {§0.60

30,40

o

CO U. i£U u

V

So. 00

1 r 1 1 o——

H = 50m

A- —A H=35m

X - --X H = 20m

Shearing Force

1 J

0.0 5.0 10.0 15.0 20.0 25.0

Distance between Tunnels (m)

FIGURE 9 COMPARISON OF INTERACTION COEFFICIENTS

FOR VARIOUS DEPTH

0.80

CaSO0)o

o

u

0)

40

20

^0.00

g 0.80

{§ 0.60

^0.40

o

ca0.20 u

03 So.oo

1 A1 1 1 —A Vs = 400m/s

C9——O Vs = 200nVs

X- - ---X Vs = 100m/s

Bending Moment

0.0 5.0 10.0 15.0 20.0 25.0

Distance between Tunnels (m)

T

T

A A Vs = 400m/s

Q O Vs = 200niys

X Vs=100m/3

Shearing Force

S 0.80

(1> 0.60

OI ^0.40

o

50.00

! I rA A Vs = 400m/s

© O Vs = 200m/s

X- X Vs=iOOm/s

Axial Force

0.0 5.0 10.0 15.0 20.0

Distance between Tunnels (m)

25.0

0.0 5.0 10.0 15.0 20.0 25.0

Distance between Tunnels (m)

FIGURE 10 COMPARISON OF INTERACTION COEFFICIENTS

FOR VARIOUS SHEAR WAVE VELOCITIES

191

DEVELOPMENT OF SEISMIC DESIGN AND CONSTRUCTION STANDARDS FOR LIFELINES

Robert D. Dikkers

Group Leader, Structural Evaluation

Building and Fire Research Laboratory

National Institute of Standards and Technology

Gaithersburg, Maryland

ABSTRACT

Section 8(b) of the National Earthquake Hazards Reduction Program Reauthorization

Act, which was approved on November 16, 1990, requires the Federal Emergency

Management Agency (FEMA) , in consultation with the National Institute of

Standards and Technology (NIST) , to submit to the U.S. Congress, not later than

June 30, 1992, a plan for developing and adopting, in consultation with

appropriate private sector organizations, design and construction standards for

lifelines. This paper discusses the process, participants, and schedule being

utilized to prepare the lifelines standards development plan. Lifeline systems

being addressed are electrical power, gas and liquid fuel, telecommunications,

transportation, and water and sewer. The plan will include the following

information for the various lifeline systems: seismic vulnerability; current

design and construction practices and standards; available knowledge to improve

existing practices; recommended standards to be developed for new and existing

construction; and recommended research to fill identified knowledge gaps.

INTRODUCTION

Earthquake Hazards Reduction Act of 1977

In October 1977, the U.S. Congress enacted Public Law 95-124, the Earthquake

Hazards Reduction Act of 1977. Passage of this Act reflected a growing

recognition that all 50 States are vulnerable to the earthquake hazard, and 39

States are subject to major or moderate seismic risk^^^ . The purpose of the Act

is to reduce the risks to life and property in the United States from future

earthquakes through the establishment and maintenance of an effective earthquake

hazard reduction program. The objectives listed in the Act for the National

Earthquake Hazards Reduction Program (NEHRP) include:

o Conduct earthquake hazard- identification and vulnerability analysis;

o Develop seismic design and construction standards;

o Develop an earthquake prediction capability;

o Prepare plans for mitigation, preparedness, and response activities;

o Conduct fundamental and applied research into the causes and

implications of earthquake hazards ; and

193
o Educate the public about earthquake hazards.

In regard to the second objective (i.e., development of seismic design and

construction standards) , a key accomplishment relating to building structures has

been the publication, dissemination, and adoption of the principles contained in

the NEHRP Recommended Provisions for Development of Seismic Regulations for New

Buildings ^^^

.

Abatement of Seismic Hazards to Lifelines: An Action Plan

In 1985, the Federal Emergency Management Agency (FEMA) asked the National

Institute of Building Standards (NIBS) , the parent organization of the Building

Seismic Safety Council (BSSC) , to prepare a plan to reduce seismic hazards to new

and existing lifelines^^^ . Under the direction of a BSSC Action Plan Committee,

specialists in all lifeline categories and in legal/regulatory, political,

social, economic, and seismic risk aspects of lifeline hazard mitigation were invited to prepare issue papers. Forty- two issue papers were circulated among

peers and were the basis of discussions by the 65 participants at a workshop held

November 5-7, 1986, in Denver, Colorado. The major product of the workshop was an action plan titled Abatement of Seismic Hazards to Lifelines: An Action

Plant^l .

The Action Plan recommended actions in four areas: (1) public policy, legal and

financial strategies; (2) information transfer and dissemination; (3) emergency

planning; and (4) scientific and engineering knowledge. Of the almost $29

million required for the recommended activities, about $21 million was for

scientific and engineering knowledge (e.g., improve geotechnical knowledge;

increase knowledge of performance of specific components; develop improved

equipment and material for use in seismic resistant construction; develop design

criteria, codes and standards of practice for design, construction, and

retrofitting of seismic resistant lifeline facilities; etc.).

In 1989 a NIBS ad hoc Panel on Lifelines recommended that FEMA undertake a nationally coordinated program to mitigate the effects of earthquakes and other

natural hazards on lifelines'-^^ . Recommended activities included: awareness and

education; vulnerability assessment; design criteria and standards; regulatory

policy; and continuing guidance.

NEHRP Reauthorization Act of 1990

Section 8(b) of the National Earthquake Hazards Reduction Program Reauthorization

Act, Public Law 101-614, which was approved on November 16, 1990, requires the

Director of the Federal Emergency Management Agency (FEMA) , in consultation with

the National Institute of Standards and Technology (NIST) , to submit to the U.S.

Congress, not later than June 30, 1992, a plan, including precise timetables and

budget estimates, for developing and adopting, in consultation with appropriate

private sector organizations, design and construction standards for lifelines.

The plan is also required to include recommendations of ways Federal regulatory

authority could be used to expedite the implementation of such standards.

194
LIFELINES STANDARDS DEVELOPMENT PLAN

Need for Design and Construction Standards

Experiences in the 1971 San Fernando, California and the 1989 Loma Prieta,

California earthquakes and other earthquakes show that the successful performance

of lifeline systems (water and sewage, transportation, gas and liquid fuels,

electrical power, and communications) is vital for prevention of severe human and

economic losses'^^. Except for design standards for new highway bridges, dams,

and nuclear reactor facilities, no nationally recognized standards are available

in the United States for the design and construction of new lifelines or for the

assessment and strengthening of existing lifelines.

The development of design and construction standards, as mentioned above, has

been an important objective of the NEHRP since its inception in 1977. Although

significant progress has been made in the development of improved seismic

standards for new buildings, there is considerable research and work remaining

to be done to achieve a comparable status with respect to lifelines.

Recommendations which have been presented during the past 5 years for the

development of standards for lifelines, along with the U.S. congressional mandate

of 1990 for a lifelines standards development plan will establish a starting

point from which similar progress can be made in lifeline systems.

As indicated by the NIBS ad hoc Panel on Lifelines, "design criteria and

standards for lifeline hazard mitigation provide consistent minimum recommended

levels of facility engineering design and construction practice. They identify

natural hazard abatement techniques and practices for those responsible for all

phases of lifeline design, construction, and operation and serve as the basis for

model code provisions, which can be considered by local, state, and federal

regulatory bodies for adoption into ordinances and regulations.'^^"

Plan Development Process and Scope

The overall lifelines standards plan development process presently being

implemented has been established with the advice of a Steering Group organized

by FEMA. The Group, chaired by Dr. Ronald Eguchi, Chairman, ASCE Technical

Council on Lifeline Earthquake Engineering (ASCE TCLEE) , includes representatives

from FEMA, NIST, Department of Energy, Federal Energy Regulatory Commission,

National Center for Earthquake Engineering Research (NCEER) , and several members

from various private sector organizations. During its first meeting in March,

1991, the Steering Group approved a strategy for the lifelines standards

development process. The strategy included using lifelines experts to prepare

and review draft plans for the development of design and construction standards

for the various lifeline systems. The experts identified by the Steering Group

and selected to author the draft plans are:

o Water & Sewer Systems -- Mr. Donald Ballantyne,

Kennedy/J enks/Chilton, Federal Way, Washington.

195
o Transportation Systems -- Dr. Ian Buckle, NCEER, Buffalo, New York.

o Gas and Liquid Fuel Systems -- Dr. Douglas Nyman, D.J. Nyman &

Associates, Houston, Texas.

o Electrical Power Systems -- Dr. Anshel Schiff, Stanford University,

Palo Alto, California.

o Telecommunication Systems -- Mr. Alex Tang, Northern Telecom Canada

Ltd., Ontario, Canada.

o Federal Implementation & Other Issues --Mr. Crane Miller, Attorney,

Washington, DC. '.

In each of the above areas , five expert reviewers have also been identified and

selected. These individuals will review the draft plans and participate in a discussion of the plans at a workshop to be held in Denver, Colorado, on September 25-27, 1991. Approximately 85% of the key individuals involved in the

plan development process described above are active m the ASCE TCLEE.

In general, the plan will include the following information for the various

lifeline system categories: seismic vulnerability; current design and

construction practices and standards; available knowledge to improve existing

practices; recommended standards to be developed for new and existing

construction; and recommended research to fill identified knowledge gaps. It

will also contain recommended timetables and budget estimates and recommendations

of ways Federal regulatory authority could be used to expedite the implementation

of such standards. The BSSC Action Plan^^^ and NIBS ad hoc Panel report^^^ are being used as background resource documents.

The current scheduled completion date for the final draft lifelines standards

development plan is January 1, 1992. After this date, the draft plan will be

submitted by FEMA to the Office of Management and Budget for review prior to its

submission to the U.S. Congress not later than June 30, 1992.

REFERENCES

[1] National Earthquake Hazards Reduction Program. Five Year Plan for 1989-

1993 . Federal Emergency Management Agency, National Bureau of Standards,

National Science Foundation, United States Geological Survey.

[ 2

] NEHRP Recommended Provisions for Development of Seismic Regulations for

New Buildines . Building Seismic Safety Council, 1985 (Revised 1988).

[3] "An Evaluation and Planning Report -- The Lifelines Segment of the FEMA

Earthquake Program," FEMA, September 1989.

[4] Abatement of Seismic Hazards to Lifelines: An Action Plan . Building

Seismic Safety Council, FEMA- 142, August 1987.

196

I
"Strategies and Approaches for Implementing a Comprehensive Program to

Mitigate the Risk to Lifelines from Earthquakes and Other Natural

Hazards," A Report to FEMA, Prepared by the Ad Hoc Panel on Lifelines,

National Institute of Building Sciences, June 1989.

"Seismic Standards for Lifelines," Prospectus, National Civil Engineering

Research Needs Forum, January 28-30, 1991, Washington, D.C.

197

IV. SEISMIC DESIGN & ANALYSIS:

PIPELINES & TUNNELS,

PART TWO

"Data Base of Pipeline Failures, Loma Prieta Earthquake,

October 17, 1989"

L. Lund

"Behavior of Flat Underground Structures during

Earthquakes and Seismic Loads Acting on Them"

S. Mori, T. Ikeda, K. Matsushima, H. Tachibana

"Seismic Response of Super-Deep Vertical Shaft with

Circular Cross-Section"

N. Ohbo, K. Hayashi, K. Ueno

"Seismic Design Method of Shield Tunnels with

Axial Prestressing by Means of Rubber and PC Bar"

K. Matsubara, K. Urano

"Seismic Isolation for Underground Structures"

K. Ono, S. Shimamura, H. Kasai

199

DATA BASE OF PIPELINE FAILURES

LOMA PRIETA EARTHQUAKE

OCTOBER 11, 1989

Le Val Lund, P.E., M. ASCE

Civil Engineer, Los Angeles, CA

ABSTRACT

The American Society of Civil Engineers, Technical Council on

Lifeline Earthquake Engineering was awarded a grant by the

National Science Foundation (NSF) to develop a data base of

pipeline failures from the Loma Prieta Earthquake, October 17,

1989. The purpose of the project is to preserve information on

the location, pipe size, pipe material and type of pipeline

failures for the engineering, geological and seismological

community and as well as future seismic risk and lifeline

researchers. The resulting data base and methodology will be

available in a public depository, in disk format, for personal

computers, to the engineering and scientific community at the

cost of duplication.

INTRODUCTION

Lifelines

Lifelines are those services vital for people and the

functioning of an urban and industrialized society. They are

also necessary for emergency response and recovery of a community after a disaster such as an earthquake. Lifelines

include power, communication, transportation, water, sewage,

gas and liquid fuel systems.

Loma Prieta Earthquake

On Tuesday, 17 October 1989 at 5:04 p. m. (PDT) an earthquake,

magnitude Ms 7.1, occurred along the San Andreas fault in the

Santa Cruz Mountains of California. The epicenter was located

16 km (10 miles) northeast of Santa Cruz and 100 km (60 miles)

south of San Francisco, California. This large; however of

moderate magnitude, moderate event killed 62 people, injured

3, 757 people, destroyed 367 businesses and left more than

12,000 homeless. The strong shaking lasted less than 15

seconds and it is estimated to have caused more than $7 billion

in damage

.

The Loma Prieta earthquake affected the performance of almost

201
every type of lifeline system in the San Francisco and Monterey

Bay areas. The most significant were in transportation,

especially the loss of the Cypress Street Viaduct on Interstate

880 and the collapse of a linking span on the San FranciscoOakland Bay Bridge. The more significant damage to pipelines

occurred in the Marina and south of Market Street areas of San

Francisco, areas along the the San Francisco Bay in Oakland and

Alameda and areas along the San Lorenzo River in Santa Cruz

.

Underground pipelines were affected in unstable ground areas,

especially subjected to liquefaction. In a few cases the

inability of the these pipelines to function affected the

emergency response and recovery activities.

American Socie'ty of Civil Engineers

The American Society of Civil Engineers (ASCE) - Technical

Council on Lifeline Earthquake Engineering (TCLEE) participated

in the Earthquake Engineering Research Institute (EERI)

preliminary reconnaissance survey of the Loma Prieta

earthquake, October 17, 1989. TCLEE members of the Earthquake

Investigation Committee investigated the performance of

transportation, power, gas, communications and water and

sewage facilities and prepared a report on these lifelines

which was published in the Earthquake Engineering Research

Institute professional journal. Earthquake Spectra, Supplement

to Volume 6, May 1990.

National Science Foundation

The American Society of Civil Engineers, Technical Council on

Lifeline Earthquake Engineering was awarded a grant (BCS9011325) by the National Science Foundation (NSF) to develop a data base of pipeline failures from the Loma Prieta Earthquake,

October 17, 1989. The purpose of the project is to preserve

information on the location, pipe size, pipe material and type

of pipeline failures for the engineering, geological and

seismological community and as well as future seismic risk and

lifeline researchers. The resulting data base will be

available in a public depository, in disk format for personal

computers, to the engineering and scientific community at the

cost of duplication.

OBJECTIVES

Functional seismic performance of pipelines is necessary to

permit the emergency response and recovery of a community after

an earthquake. Water supply is necessary for public fire

fighting purposes, sewer pipelines are necessary to carry waste

202
away and prevent a situation of pollution which could cause

illness or disease to the public and gas supplies are critical

for heating and cooking for essential facilities such as

hospitals. Gas and liquid fuels are essential for operation of

emergency vehicles and equipment, and electric power generation

to

provides electricity for emergency services. Also, the loss of

lifeline services could result in a economic loss to business

and industry.

The objectives of the project is to preserve data that may be

lost, to place into a form useable by the research community

and make available the data and methodology that may never be

published.

SCOPE OF PROJECT

1. Establish advisory group to review objectives of the

project and to determine the type of data to be preserved.

2. Collect the data on pipeline damage from agencies.

3. Convert location of pipeline damage into latitude and

longitude coordinates.

4. Enter location and other statistical information into

existing commercially available software into data base

program adaptable for use on the personal computer.

5. Place data in disk form and methodology in a public

depository available for use by future researchers.

Data Collection

In the process of contacting more than 35 water, sewage, gas

and liquid fuel agencies it has become evident that a number of

them have documented the location of damage to underground

pipelines. Also some them have identified the size, pipe

material, type of damage and other features of the damage. In

contrast, there are a number of agencies who have concentrated

on restoring the lifeline service and have minimized the

documentation of the damage and mainly concentrating on the

cost of repair. The cost information is necessary for

completing the Federal Emergency Management Agency (FEMA)

Damage Survey Report (DSR) which may permit reimbursement of

the cost of repair for public agencies.

203
The Advisory Group recommended collecting the following basic

information on the damaged pipelines:

Lifeline conveyed - Water, sewage, storm water, natural gas

or liquid fuels.

Size - Diameter and thickness

Material - Steel, cast iron, ductile iron, plastic, copper,

concrete (reinforced or unreinforced) , concrete

cylinder, etc.

Pipe or fitting - Pipe, valve, elbow, tee, reducer, etc.)

Joint type - Bell and spigot, welded (gas or electric arc) , rubber gasket, bolted, mechanical coupling, butt strap,

etc

.

Age - Year of installation.

Type of damage - Tension, compression, bending, corrosion,

etc

.

Leak or Break - Leak - Lifeline continued to function with

minimum loss of service. Break - Lifeline damaged with

complete loss of function.

Other desirable information, but not always available.

Method of Repair - Repair clamp, welding, coupling, replace

pipe or fitting, etc.

Water Table - Elevation or depth to water from ground

surface.

Foundation Material - Description of bedding or trench

material

.

Coating and Lining - Cement mortar lining or coating, coal

tar enamel lining or coating, multiwrap coating, etc.

Cathodically Protected - Yes or no. -

Coordinate Conversion

Location of pipeline damage is plotted from the information

provided by the lifeline agency on maps published by the United

States Geological Survey (USGS) or equivalent maps which show

latitude and longitude coordinates. USGS publishes maps both on

15 minute (1:24,000 scale) and 30 minute (1:100,000 scale) with

latitude and longitude coordinates.

204
Computer Program

The computer program was developed using FoxBASE+ on the

Macintosh computer. This program generates a source code that

is compatible with dBASE . dBASE is available on both Macintosh

and IBM or IBM compatible personal computers.

Problems

There is a significant difference in the amount of damage

information available. Not all agencies keep detailed records

of the type of damage

and method of repair. Most public agencies keep records on the

cost of repair for possible reimbursement by FEMA. This

reimbursement is not available to private agencies; however,

they may be eligible for low interest loans if the earthquake

impact area is declared a "disaster area" by a state and

federal governments.

Some agencies either because they acquired old systems,

newly created organization assembled from a group of

agencies or have no technical staff resources have

information on their existing system.

In the Loma Prieta earthquake a flyer with a check sheet was

distributed by the TCLEE Earthquake Investigation Committee

(EIC) to a number of lifeline agencies after the event

requesting they collect the information described above under

data collection. The agencies were informed a TCLEE EIC

representative would be contacting them in about 30 days to

collect damage information for placing into a report on the

performance of lifelines in the earthquake. In reality only a very few followed these suggestions.

In the future in domestic USA earthquakes the flyer and check

sheet should be distributed; however, it should be recognized

there may be very compliance.

DISSEMINATION

Provide computer program (floppy disk) and report on

methodology for permanent storage in a public depository, such

as, the National Information Service for Earthquake

Engineering, University of California, Richmond, CA; National

Earthquake Engineering Research Center, Buffalo, NY; Southern

California Earthquake Center, University of Southern

California, Los Angeles, CA; and other locations, and available

to any researcher for the cost of duplication.

205
CONCLUSIONS

The data would be used by geotechnical researchers to determine

damage as related to different geological conditions or

seismicity. Seismic risk researchers would use the

information for seismic risk analysis of lifeline systems. The

would be used to improve the performance lifeline systems.

The methodology could be used on future earthquakes, collecting

data in the same manner and the damage data into the same data

base, so that accumulation of data can be placed in a data

bank representing different magnitudes, geological and

topographical conditions.

ACKNOWLEDGEMENTS

The author appreciates the representatives of the many lifeline

agencies who took the time to provide the data and to Anschel

Schiff the Coprincipal Investigator.

REFERENCES

Earthquake Engineering Research Institute, Loma Prieta

Earthquake Reconnaissance Report, Earthquake Spectra,

Supplement to Volume 6, May 1990, El Cerrito,CA

Personal contacts with lifeline agencies by Le Val Lund.

Prepared for the Fourth U.S. - Japan Workshop on Earthquake

Disaster Prevention for Lifeline Systems, Los Angeles, CA,

August 19 -21, 1991.

LL 8-7-91

206
BEHAVIOR OK FLAT UNDERGROUNT) STHRUCTURES

DURXNG EARXHQUAIiES

AND SEISVUC UOADS AOrXNG ON THEM

Shin 'Ichiro MORI

Senior Research Engineer, Registered Engineer

Taka'aki IKEDA

Research Engineer

Ken'ichi MATSUSHIMA

Manager

Hideo TACHIBANA

Manager, Registered Engineer

TOBISHIMA Corporation, Technological Dept.

ABSTRACT

Anticipating the future construction of underground urban facilities,

such as underground roads and shopping centers, the authors have been

conducting a study of seismic design methods for flat underground structures.

During an earthquake, all faces of an underground structure receive

lateral and shear forces from the surrounding ground.

However, seismic load as defined under the seismic deformation method, a seismic design method for underground structures, is relative lateral

displacement between the structure and the ground along the sides of the

structure. Hence, other forces including shear force that should act

laterally on the structure are ignored, and stresses occurring in the

structure are underestimated.

Therefore, the same structure was analyzed using both a dynamic FEM

model and a static frame model supported by Winkler springs. Then, seismic

loads on underground structures that should be assumed were considered by

comparing the results of those analyses.

As a result, it was confirmed that a major part of seismic load

acting on a flat underground structure was shear force acting on the top

and bottom slab of the structure, and that tendency became more pronounced

as the width of the structure increased.

These results indicate that seismic loads assumed for the seismic

design of a flat underground structure should include shear forces acting

paralelly on faces of the structure in addition to lateral seismic loads on

the sides of the structure as assumed by the seismic deformation method.

207
Int roduct ion

In anticipation of the future construction of underground urban

facilities, such as roads, streets, shopping centers, parking lots and

factories, the authors have been conducting a study of seismic design

methods for relatively flat and wide large-scale underground structures

(hereafter called "flat underground structures" ). ^^"^^ Seismic load as defined under the seismic deformation method, a today's seismic design method of underground structures, is a relative

lateral displacement between the ground and the structure, due to ground

deformation, acting on the sides of the structure. However, there will be

not only normal components, but also shear components of loads acting on all faces (the sides and the top and bottom) of an underground structure.

In a flat underground structure, in particular, shear force acting on the

top and bottom of the structure is considered to constitute the major part

of seismic load, because of the characteristic configuration, of the structure. Hence, this study is aimed at (1) analyzing seismic load acting on flat underground structures, and (2) studying the applicability of the con- ventional seismic deformation method and a few improved methods.

In this paper, characteristics of the behaviors of a flat underground

structure and the surrounding ground during earthquakes are discussed, and

influences of the construction depth and the width-height ratio on various

stresses occurring in the structure are investigated through two-dimensional dynamic FEM analysis'*^ and one-dimensional multiple reflection

analysis^^ (hereafter called "1-D MR analysis"). Based on the responses of

the ground and stresses in the structure obtained from the dynamic FEM

analysis, the loads acting on the structure during earthquakes are divided

into smaller elements. By comparing them with the results from static

analysis of frames supported by soil springs, seismic loads that should be

applied in the static seismic design of the flat underground structure are analyzed. All analyses are performed assuming the linearly of the materials .

Ground Conditions and Structure model

The following basic configurations were assumed in this study.

1. A 40 meter subsurface ground layer with a primary natural frequency of

1 Hz,

2. A horizontally stratified two-layer ground with an impedance ratio of

about 1/3, and

3. A multiple box cellular structure consisting of a number of 5 meter

high, 10 meter wide box shaped hollow modules arranged side by side.

These ground conditions are shown in Fig. 1. The influences of

width/height ratios were then examined for structures with widths of 10,

30, 100, and 300 meters constructed at a depth of 10 meters to the foundation slab. Similarly influences of the construction depth were examined

for a structure 100 meters wide constructed at depths of 5, 10, and 30

meters. It was assumed that the thickness of the walls and top and bottom

slabs was 80cm, for all structures. The study of the width/height ratio is

shown in Fig. 2.

208
Ground surface

Subsurface layer

Unit weight

Shear wave velocity

Poisson' s ratio

Damping factor

7=1.7 tf/m*

Vs=160 m/s

v=0. 45 h=0.02

Unit weight

Shear wave velocity

Poisson' s ratio

Damping factor

7=2.0 tf/m'

Vs=400 m/s

i/=0. 35 h=0.02

Fig.l Model of ground

I I I I Underground structure

(a) 10m (b) 30m (c) lOOm

(unit module) (3 modules) (10 modules)

1 1 ] I I r 1 1 1 I T T I r I 1

3 0 0 m

1 1 I I 1 I

I

1 1 1 1 1 1

1mH 1

(d) 300m

(30 modules)

Fig. 2 Models of underground structures of various width

Frequencies considered in the analyses were between 0 Hz and 8 Hz.

Changes of the ground surrounding the structure under the influence of the

structure were regarded as responses on the ground directly above the

center of the structure (hereafter called "central ground surface"). Input

seismic waves used in the analyses were El Centre 1940 NS components, Taft

1952 EW components, and Hachinohe 1968 NS components. It was also assumed

that the input seismic waves SV waves as upward incident waves.

Influences of Width-Height Ratio and Construction Depth

The influences of width/height ratio

The influence of a width/height ratio were studied and results are summarized in Fig. 3.

These figure indicates that all responses increase as the width increases, and that the changes in stresses are closer to the changes of

maximum acceleration response spectrum values than to those of maximum

acceleration values.

Fig. 4 shows changes of the mean value of the ratio of the acceleration response spectra of the central ground surface to those of the ground

surface of the free field for the three waves, in relation to the width of

the structure. Some changes can be observed in frequency ranges corresponding to the 2nd and 3rd modes for the subsurface ground. In particular, maximum responses on the central ground surface become predominant

around the 2nd natural frequency range of the subsurface ground.

209
.2 1. 4

CO

t-i

«3

1. 2

1. 0

-1—I—I I 1 1 1

1

|

1—I—I I 1 1 1

1

1

Input earthquake

not ions • El centro A Taft Hachinohe

_i I

I 1 f I 1 1

1

_i I

I 10 100

Structure' s width (m)

(a) Relationship bewteen structure's width

and ratio of maximum acceleration

(Central ground surface / Ground surface of the free field)

OS

o

D.

co

a.

1. 4

1. 2

1. 0

T I I 1 M 1 l{ 1 1 ( 1 1 1 1

1

1 1 1 1

Input earthquake

mot ions • El centro ^ 'A A A Taft Hachinohe

' Ill 1 1 1 1 1 1 1 1

1 10 100

Structure'

s

width (m)

(b) Relationship bewteen structure's width and ratio

of maximum acceleration response sprctrum value

(Central ground surface / Groung surface of the free field)

I

1. 4 o

c

JO

1. 2 -

1. 0 -

I I 1 I I I I I -l—I I I 1 1 1

1

Input earthquake

mot ions

El centro A A Taft Hachinohe

_i I I I I 1 1

1

1 I 1 I 1 1 1 1

1

1 I 1

to 1 10 100

Structure' s width (m)

(c) Relationship between structure's width and

ratio of maximum bending moment at the right-bottom

corner of structure to unit module structure

Fi&.3 Relationship between structure's width and some dynamic responses

210
o

CDQ.

atn

03

1. 4

1. 2

1. 0

0. 8

.2 0. 6

1—I—I—I I 1 1

1

I I 1 1 1 1 1

1

~1 1—I—I I I I L

Structure' s »idth

I 0 m

3 0m

10 0m

3 0 0 m

0. 1 1 10

Natural period (sec.

)

Fig-. 4 The influence of structure's width

on acceleration spectrum(10ni in depth)

[Central ground surface / Ground surface of the free field]

Influences of the construction depth

Influences of the construction depth were investigated for the width

of lOOm. Fig. 5 shows similar changes of the mean value of the acceleration response spectrum ratio for the three waves, indicating considerable

variations depending on construction depths. The fact that responses at

the central ground surface become greater or smaller depending on construction depths suggests that the construction depth is an important factor.

<aQ.

CO

<1> I

d)

.2 1. 0 w

l_

<D<D8 0. 8

o

o

0. 6

0. 1 1 10

Natural period (sec.

)

Fig. 5 The influence of structure's construction

depth on acceleration spectrum (lOOra in width)

(Central ground surface / Ground surface of the free field]

211
study of the Applicability of One-Dimensional Multiple Reflection

Analysis Method and Influence of the Rigidity of Structure

Applicability of 1-D MR analysis

In order to determine the cause of the variation of responses at the

central ground surface depending on the widths and depths of the structure,

an assumed, 100m wide structure was replaced with a layer with the apparent

weight and the apparent shear stiffness of the structure and was subjected

to 1-D MR analysis. Fig. 6 shows the transfer functions for the central

ground surface obtained from FEM analysis and 1-D MR analysis for the

construction depth of 5ra. The FEM model was meshed so that frequencies of

up to 32Hz could be considered. In the FEM analysis, marked input loss

effects^^ due to ground confinement by side walls were observed at frequencies of 14Hz and above, but the results of these analyses agreed well at

frequencies between OHz and 8Hz. This revealed that 1-D MR analysis is an effective method for examining the behaviors of flat underground structures

and surrounding grounds during earthquakes.

Confidence range of frequency

in the FEM analysis

OHz 8Hz

3

o

_ 1 1 1 1 1 1 1 1 1 h 1 i \

1 1 1 1 1 1 1 1

1

1 1 1 1 1 1 J 1

one-<Ji«ensional eultiple

reflection analysis FEM analysis Mm

\ A

1 1 1 1 1 1 1 1 1 t 1 1 1 I 1 r 1 1 1 1 1 1 1 1 t"'! 1 0 10 20 30

Frequency (Hz)

Fig. 6 Comparison of transfer functions between one-dimensional

multiple reflection analysis and two-dimensional FEM analysis

Influences of the rigidity of structure

Influences of the ratio of apparent impedances of the subsurface

ground to those of the structure on the responses at the central ground

surface were examined through 1-D MR analysis. Fig. 7 shows the ratios of

the amplification factors of the transfer function for the central ground

surface in relation to the ground surface of the free field, to the apparent impedance ratios of the structure to the ground. From this, it can be

said that the above-mentioned amplification results from dynamic interaction due to the apparent shear stiffness of the structure of 0.62 and the

impedance ratio of 0.55. This indicates that responses of the overburden

soils can be reduced by increasing the thicknesses of elements of the

structure and raising the apparent impedance of the structure to a level

higher than that of the subsurface ground.

212
o >> c o

tt-c 0)

<D CD <D

CO

-l-> (-

03 CO

O

Q.

C/3 O) -oO o

00

•o

1. 4

1. 2 o

.'^ 1. 0 -

0. 8

"1 I I I

I

I I I I ]

I—I—I—I—

I—I—I—I—

r

#- 1st --A 2nd -- 3rd

-J—I—I I I I I 'III

0. 0 0. 5 1. 0 1. 5 2. 0 w Apparent impedance ratio of

underground structure to subsurface layer

Fig. 7 Influence of apparent stiffness of structure

on dynamic response characteristics

at the central ground surface

Determination of the designable structure and dynamic 2-D FEM analysis

of a soil-structure system

Determination of designable structure

With the structures considered earlier, if they were to be constructed at deep levels, dynamic responses of soil above those structures would

be amplified and substantial shear reinforcement needed to be considered at

the design stage because of the thinness of elements of the structure in

relation to the width of the box module. Therefore, analyses similar to

those performed for ordinary structures could be conducted by keeping the

apparent impedance ratio at 1.0 or above or modifying the structure so that

it could be designed ordinarily as under ordinary stationary load. The

modified structure was a multiple cellular box structure consisting of a series of 5m high, 7.5m wide hollow rectangular modules set side by side.

The thickness of all elements of the structure was set at 1.0m. Structures

of widths of 7.5m, 22.5m, and 75ra, corresponding to 1, 3, and 10 modules

respectively, were considered, and the construction depth was assumed to be

10m. If the width of the structure is 75m, then the apparent impedance

ratio is 1.25, indicating, according to Fig. 7, that responses of soil

above the structure are smaller than those of the ground surface of the

free field.

Model of d3niamic 2-D FEW analysis of a soil-structure system

Fig. 8 shows an analytical model for the width of structure of 75m.

Since the soil-structure system was symmetric, only the right half of the cross section was analyzed, and the degree of vertical freedom on the leftside boundary was fixed. The lower boundary are assumed a viscous boundary^^ and the right-side boundary are assumed an energy transmitting boundary by various depth method. The semi infinity of the ground was considered, but out-of-plane dissipation of waves was not. This model was sufficiently accurate at frequencies between OHz and 8Hz. Through the FEM

analysis, responses of the ground and responses of various stresses occurring in the structure were examined, and seismic loads acting on the structure were considered.

213
Center of analysis model

Horizontal

rol ler

boundary

(Axi-symmetric

condition)

87.5

42.5 5_.0,

Underground stracture

40.0

Viscous boundary

Energy transmitting

boundary

Free field

(Semi-inf ini te visco-elastic

soil layer)

Unit:meter(s)

O Investigate point of element stresses Fig. 8 2-dimensional FEM model (75ra in width and lOra in depth)

Static Frame Analysis under (Equivalent) Seismic Load

Objective of analysis

Seismic loads that were expected to act on underground structures

during earthquakes were divided by causes and components into smaller

elements. Those load elements were then assumed to act on a planar frame

model having panel points supported by soil springs in the vertical and

shear directions. The stresses thus obtained were compared with the results

from FEM analysis, and the seismic loads that would be assumed to act on underground structures were considered.

Component of seismic load divided by factors

Table 1 shows loads divided by factors, and seismic loads in four

cases with different combinations of divided loads. In Case 1, lateral

relative displacements of the ground to the structure were assumed to work

through soil springs on the sides of the structure; these loads correspond

to those obtainable from the conventional seismic deformation method. In

Case 2, in addition inertia force was added. In Case 3, shear forces were assumed to act on the top and bottom of the structure. For Case 4, shear

forces were also assumed to act on the sides of the structure. Inertia

force was calculated based on the acceleration of the ground of the free

field. Shear force was calculated as summation of shear stress occurring

in the ground at the depth of the structural member in question times the

area to be covered by panel points. Soil spring values were calculated

through static analysis using an FEM model.

Table 1 Combination of seismic loads for static analysis

with frame model supported by soil springs

Factors and components of seismic loads

Combination of seismic loads

Case-l Case-2 Case-3 Case-4

0 Relative lateral displacement

acting on the side wall

O o O o

(2) Inertia force acting on the structure o O o

0 Shear force acting on the upper

and lower slabs of structure

O o

® Shear force acting on the side wall o

214
Contribution of each factor and component of seismic load

Fig. 9 shows stresses at end corners obtained from the static analysis, in terms of ratios to the stresses obtained from the FEM analysis.

Stresses obtainable from Case 1 accounted for only 10%-20% of the results

of the FEM analysis. These ratios became lower as the width of the structure increased. This means that the use of the lateral displacements of

the ground acting on the sides of the structure alone, will result in an under estimation of the seismic loads. There are no substantial differences if inertia forces are added to horizontal displacements acting on the

sides of the structure. The stresses obtained in Case 3 could be shown to

be much closer to the results of the FEM analysis by Introducing shear

forces acting on the top and bottom slab of the structure. For a 7.5ra wide

structure, about 70% of bending moments and shear forces, and about 90% of

axial forces could be expressed. As the structure became wider, these

ratios approached 100% and exceeded 80% when the width of the structure was

75m. It is thought, therefore, that the shear forces acting on the top and

bottom of the structure constitute the major part of seismic loads on flat

underground structures and have a considerable affect on the member stresses produced. It was confirmed that by introducing all loads that were

considered to act on a flat underground structure in Case 4, seismic loads

could be expressed as accurately as by the FEM method. It was also con- firmed that this tendency did not depend on the types of seismic waves.

Note, however, that axial forces were slightly overestimated.

215
Imput earthquake motions

Narrow

Structure' s width

El centro Taft Hachinohe

^Wide

2 3 CASE

Case of 7. Sm width

2 3 CASE Case of 22. Sm width

1 2 3 CASE

Case of ,75. Om width

(a) Response of bending moment at the lower end of the side wale

2 3 CASE Case of 7. 5m width

1 2 3 CASE Case of 22. 5ra width

(b) Response of shear force at the lower end of the side wale

1.6

1.4

2 3 CASE

Case of 75. Om width

2 3 CASE Case of 7. 5m width

2 3 CASE

Case of 22. 5m width

2 3 CASE

Case of 75. Om width

(c) Response of axial force at the right end of the bottom slab

All graphs are plotted as ratio of stress [frame analysis/FEM analysis]

Case-1:® Relative lateral displacement acting on the side wall Case-2:Case-i + (2) Inertia force acting on the structure Case-3:Case-2 + (3) Shear force acting on the upper and lower slabs of structure Case-4:Case-3 + ® Shear force acting on the side wall

(D Relative lateral displacement

acting on the side wall

Inertia force acting on the structure

Shear force acting ® Shear force acting

on the upper and lower the side wall slabs of structure

Fig. 9 Element stress ratio at the right lower corner of

static analyses of frame model to dynamic analyses of FEM model

216
Conclusions

(1) Responses of the overburden soil above the structure and responses of

various member stresses of the structure increase when the apparent

impedance of the structure is smaller than that of the ground. Hence,

such responses can be reduced by increasing the apparent impedance of

the structure.

(2) The responses of a relatively flat underground structure and its over- burden soil can be evaluated by one-dimensional multiple reflection

analysis

.

(3) Analysis of static frames supported by earth springs in the vertical

and shear directions revealed that if the consideration is limited to

the horizontal displacement and inertia forces acting on the sides of

a structure the stresses will be underestimated. By applying shear

forces on all faces of the static frame model, the stresses can be

evaluated as accurately as by FEM analysis.

(4) Major seismic loads for a flat underground structure are shear forces

acting on the top and bottom slab of the structure.

Future Directions

This study revealed characteristic behaviors of a flat underground

structure and surrounding ground during an earthquake, along with major

seismic loads acting on the structure.

In order to establish a seismic design method for flat underground

structures, which is the ultimate goal of this study, there is a need for

further investigation of behavioral differences depending on the irregularity of the ground and construction depth, as well as simple methods for

calculating seismic load, and methods for calculating soil spring constants .

Acknowledgments

These studies were conducted as a cooperative research into the

development of seismic design method of underground structures through the

technology research and development regarding use of underground space in a comprehensive research project.

We would like to express our appreciation to Dr. K. KAWASHIMA of

P. W.R.I. (Public Works Research Institute) and committeeman in the working

group for valuable discussion.

We would like to thank K. MASUBUCHl, director of Tech. Dept. and

S. OHGAWARA, director of Tech. Dept., TOBISHIMA Corporation, for valuable

supports.

REFERENCES

1) TOBISHIMA Corporation: 5th chapter, 2nd paragraph. Behavior of flat

underground structures and surrounding ground during earthquakes and

seismic loads acting on the upper and bottom slab of structure. Development of Seismic Design of Underground Structures, Cooperative Research Report of PWRl, 1990.3, pp.l91-242(In Japanese).

217
2) Shin* Ichiro Mori and Taka'aki Ikeda: Behavior of flat underground

structure and surrounding ground during earthquake, Proc. of the 45rd

Annual Conference of the Japan Society of Civil Engineers, 1, 1990.10,

pp.ll74-1175(In Japanese).

3) Shin'ichiro Mori, Taka'aki Ikeda, Ken'lchl Matsushima and Hideo

Tachlbana: Behavior of flat underground structures during earth quakes

and seismic loads acting on thera, Proc. of the 21th JSCE Earthquake

Engineering Syniposiura-1991, 1991.7, pp.473-476(In Japanese).

4) Lysmer, J., Udaka, T., Tsai, C.-F. and Seed, H. B.: FLUSH - A Computer

Program for Approximate 3-D Analysis of Soil-Structure Interaction

problems, Earthquake Engineering Research Center, University of California, Berkeley, Report No. EERC 75-30, November, 1975.

5) Schnabel, P. B. , Lysmer, J. and Seed, H. B. :SHAKE-A Computer Program

for Earthquake Response Analysis of Horizontally Layered Sites, Earthquake Engineering Research Center, University of California, Berkeley,

Report No. EERC 72-12, December, 1972.

6) Shin'ichiro Mori, Shigeru Miwa, Masato Muto and Koichiro Tani: Interaction between soils and underground structure observed in seismic motion

and in raicrotreraor, Proc, of the 7th Japan Earthquake Engineering

Symposium, December 1986., pp925-930(In Japanese).

7) Lysmer, J. and Kuhlemeyer, R. L. : A Finite Dynamic Model for Infinite

Media, Jour. Engineering Mechanics Division, ASCE, Vol. 95, No. EM4,

pp. 859-877, August, 1969.

8) Chen, J.C., Lysmer, J. and Seed, H.B.: Analysis of local vibrations in

free field seismic ground motion. Report No. EERC 81-03, Earthquake

Engineering Research Center, University of California, January 1981.

218
SEISMIC RESPONSE OF SUPER-DEEP VERTICAL SHAFT WITH CIRCULAR CROSS-SECTION

By

Naoto OHBOD, Kazuo HAYASHI2), and Kenj i UEN02)

1) Senior Research Engineer

2) Research Engineer

Kajima Institute of Construction Technology

and

Kunihiko KATO

Japan Sewage Works Agency

ABSTRACT

In order to clarify the deformation of super-deep vertical structure due to

earthquake, the earthquake observation is carried out at a super-deep vertical

shaft with a circular cross-section having a 22 ra outer diameter and 99 m depth.

It was found that deformation of the EW component of the shaft is predominantly

first vibration mode, and that of the NS component is predominatly second vibration mode. The difference of the deformation of the horizontal component of the

super-deep vertical shaft is closely related to the connected shield tunnel

direction.

INTRODDCTION

There is a great demand for a development of super-deep underground urban space

in Tokyo Metropolitan area. In the Tokyo Metropolitan area, subway tubes and

other underground structures are crisscrossed, therefore it is difficult to con- struct underground structures without interfering with such existing structures.

Consequently it is necessary to construct the underground structure deeper than

existing structure foundations and tunnels in the ground.

A construction technology of super-deep continuous underground wall has been

developed to apply to earth retaining wall for large scale excavation and wall

thickens by a super-deep diaphragm wall method. In the near future, the construction of the super-deep vertical shaft as a starting shaft for a shield tunnel or ventilation of super-deep tunnel by using super-deep continuous underground wall will be increasing. However, a seismic response behavior of superdeep vertical structures is not clear so far, moreover, observed records of

219
shafts during earthquakes are limited in number (Refs. 1,2).

The earthquake resistant design of underground structure was made by the response

displacement method to compute stresses and strains on the structure due to a fundamental deformation of the surrounding ground during earthquakes. In superdeep underground structure such as a vertical shaft, the most important thing is

to evaluate fundamental deformation of the surrounding ground. However, the

deformations of the super-deep shaft due to surrounding ground conditions and

earthquake characteristics, such as seismic wave propagation of bed rock,

epicentral distance, magnitude and frequency components, have not yet been sufficiently clarified.

In order to develop rational and economical earthquake-resistant design for

super-deep vertical structure, it is necessary to understand seismic response behavior of the shafts. The purpose of this paper is to clarify the deformations

of the super-deep shaft and surrounding ground due to observed three earthquakes

that have different epicentral distance.

OBSERVATION STRUCTURE, SITE AND SYSTEM

The observation site is located in the West of the Tokyo Metropolitan area. Figure 1 shows a vertical section in NS directional of the super-deep vertical

shaft with circular cross-section, soil profiles and location of instruments.

The shaft was constructed using super-deep continuous reinforced concrete underground wall, which was constructed by a slurry-assisted excavation method and a diaphragm wall method. The shield tunnel is at the depth of 50.8 m because of

the shield tunnel have to pass through under foundation piles. The depth of

shaft is 99 m for shutting off underground water in the shaft. The shaft has

circular cross-section with outer diameter of 22 m and the thickness of the wall

is 1. 2 m.

The surrounding soil layers consist of alluvial silt and sand, diluvial clay,

gravel and mudstone. The values of the Shear Wave velocity are assumed by using

relation between an N Value of standard penetration test and Shear Wave velocity.

These values are good corespondent to seismic wave propagation time delay from

observed records.

As shown in Fig. 1, seismographs were installed at three different depths (K1;GL48m, K2;GL-24m and K3;GL-7m) in the shaft, and at four locations of surrounding

ground. At surrounding ground, seismographs were installed at two different

depths (at the bottom of the shaft (Gl;GL-99m) and G2;GL-48m), and at two surface

points (G3, G4;GL-lm). Velocity servo seismographs, which provide high signalto-noise ratios in the measurement of long-period components, were used, and wave

220
forms of velocity amplitudes have been being observed. Total components are 21

components for velocity wave forms and 11 components for acceleration wave forms

from, mainly, the ground. These components are being observed simultaneously.

The observation system uses telephone lines for reporting the outbreak of

earthquakes and collecting earthquake data.

OBSERVED EARTHQUAKES

More than twenty earthquakes have been observed since the installation of the instruments. So far ten earthquakes (four of which had a maximum acceleration

amplitude of 10 gal or more) with a maximum surface velocity amplitude of 0.1

kine (cm/sec) or above have been observed. Three of these with relatively larger

magnitude and deference of epicentral distance, such as short epicentral distance

(15 km), middle (146 km) and distant (842 km), have been taken as examples.

Table 1 summarizes a characteristic of earthquakes and maximum amplitudes of

three earthquakes. The location of observation site and epicenter of three

earthquakes in Table 1 are shown in Fig. 2. The location of epicenter of Event

No. 2 earthquake is out of the Fig. 2, so, the symbol indicating this Event is

just showing the relative position to the earthquake wave propagation direction.

RESPONSE OF SHAFT AND FREE-FIELD SOIL

Figure 3 shows an example of recorded EW component velocity time histories at the

ground (observation points G3 and G2) and in the shaft (observation points K3 and

Kl) due to Event No. 1 and No. 2 earthquakes. Event No. 1 had a short epicentral

distance and Event No. 2 had a distant one. In Event No. 1, a short period component can be seen and a duration is very short. Moreover, the amplitude of the

shaft is smaller than that of the ground. On the other hand, in the response of

the shaft and the ground for the distant earthquake, which have long period com- ponent and long duration, the time histories of the shaft and the ground are

similar.

Figure 4 shows a superimposed Fourier Spectra, which are obtained by the velocity

time history of the horizontal component in the shaft (observation point K3) and

on the ground (observation point G3) for Event No. 1 and No. 2. A solid line cor- responds to the ground and the dash line corresponds to the shaft. Event No. 2

may be regarded as an example of a distant that usually contain considerably

strong power in low frequency region. The Fourier Spectra of EW and NS com- ponents of the shaft and the ground has a similar shape. Moreover, a peak

frequency of the shaft and ground is almost same. On the other hand. Event No.

1

shows a typical feature of the short epicentral distance. Very high frequency

component is predominant in this earthquake as shown in Fourier Spectra for both

shaft and ground in Fig. 4. NS component of the ground has a single dominant

frequency at around 6 Hz, and EW component of the ground has two dominant

221
frequencies at around 4 and 6 Hz. However, EW and NS component of the shaft have

not so clear dominant frequency. It appears that the dominant frequency and

amplitude of the ground due to the short distance earthquakes different from

those of the shaft. However, response of the ground and the shaft in distant

earthquake is almost same.

A vibration characteristic of the shaft can be recognized by frequency response

function of the velocity at the top of the shaft with respect to input motion at

the bottom. The frequency response function of the horizontal component at the

top of the shaft, K3, corresponding to Fourier Spectra of input motion, Gl, for

three earthquakes are shown in Fig. 5. On the basis of Fig. 5, the vibration

characteristics of the shaft during different epicentral distance earthquakes

have the dominant frequencies of 1.0 and 2.0 Hz in the EW component and NS component. The frequency around 1. 0 Hz is most predominant in EW component, and the

frequency around 2.0 Hz is predominant in the NS component. The frequency of 1.0

Hz is corresponding to fundamental vibration mode of the shaft, and that of NS

component is around 2.0 Hz which correspond to second mode of the shaft. It seems that the difference of the predominant frequency of the shaft depends on

the connection of the shield tunnel in NS direction.

Figure 6 shows a distribution of three components of amplitude ratio for Event

Nos. 1, 2 and 3, which are based on amplitude ratios at each observation point in

the ground and the shaft corresponding to the maximum amplitude of earthquake mo- tion observed at point Gl. The distribution of the amplitude ratio of horizontal

component of the ground is independent of difference of epicentral distance of

three earthquakes, and corresponds to fundamental mode shape. On the contrary,

UD component on the ground, the distribution and amplification ratio are different from the three earthquakes. The amplitude ratio of the shaft is smaller

than that of the ground. EW component corresponds to fundamental mode shape,

while NS component is different. This may be explained by the connecting the

shield tunnel to the shaft.

CONCLUSIONS AND REMARKS

Through the observation of the dynamic behavior of the super-deep vertical shaft

and its surrounding ground due to earthquake, the deformation of the shaft was

investigated. The results can be summarized as follows:

1. It is found that the deformation of the shaft is affected by the earthquake

epicentral distance and frequency spectra of the input motion.

2. The deformation of the shaft shows an influenced by a connecting of the shield

tunnel.

The authors intend to continue seismic observation, and based on accumulated

data, investigate the relationships between the magnitude of earthquakes and in222
put earthquake motion, and the behavior of the ground and shafts during

earthquakes.

FUTURE DIRECTIONS

In this paper, these are conclusions drawn from the observed three typical

earthquake motions. These results show the necessity of the earthquake array observation consisting of more than two or three seismometers installed in the

shaft and the surrounding ground. In order to investigate relation of deformation of the vertical shaft and surrounding ground, it is necessary to install the

seismograph and measure the reinforcing-bar stress of the shaft.

In the seismic design point of view, it is necessary to investigate the deformation of the super-deep vertical shaft and surrounding ground due to dynamic

analysis by axisymmetric dynamic finite element method and seismic design of a very simple cylindrical vertical structure.

Final stage of this earthquake observation of this super-deep vertical shaft is

to develop rational and economical earthquake-resistant design for super-deep

vertical structures.

REFERENCES

1. Ohbo N. , Hayashi K. and Ueno k. , Seismic Response of Shaft and Shield Tunnel

(in Japanese), Proc. of the 44th Annual Conference of the JSCE, 1120-1121,

(1990)

2. Kaizu N. , Seismic Response of Shaft for Underground Transmission Line,

Proceedings from the Third Japan-U. S. Workshop on Earthquake Resistant Design

of Lifeline Facilities and Countermeasures for Soil Liquefaction, 513-525,

(1990)

Table 1 Earthquake Event Information and Related Data

Event

No.

Origin

Time

M

Focal

Depth

(km)

Epicentral

Distance

(km)

Maximum Amplitude

Acc(gal) Vel(kine)

1 91:03:01 3.8 35 15 29.6 0.93 n

2 91:05:03 6.8 482 842 2.8 0. 20 n

3 91:07:14 5.2 190 146 11.5 0.67 m

* : JMA Intensity at Tokyo

223
*I600 V TPt4.00

G4

super-deep continuous underground woll —

50.8m r

shield tunnel

K3T

C K2T

Kl T

bose

20000

* 22 400"

7m

24m

G3t1 Im

G2T 48m

GIT 99m

Depth m

Nome Hm

P

t/m' Vs m/s

-3.95

-23.10

-29.3

Alluvial sand

Alluviol silt

__^.95

19 15

1.7

1.6

173

153(1)

200(11)

Alluvial sill 6.2 1 .8 275

-34 Alluvial silt 4.7 1.9 245

-502

Alluvial sand 16.2 1.9 294

-676

Diluvial Cloy 17.4 1.8 310

-78

-99

Grovel 104 1.8 584 (1) 600(11)

Muds lone 21 1.8 584(1)

525(11)

Fig. 1 Vertical Section of Shaft, Soil Profile and Location of Instrument

/ 1 p

1

V -1 1-^-^

-1

i

\ S \

37" DEPTH

01 0< 30

30 s 0< (SO

60 i a<

n4 M5 Md m f18 A ^ ^ A\ o o o O O

CD

3(5"

4x observation site

35"

34"

138" 139° cm ]

141*

50

14:

100 KM

Fig 2. Location of Epicenter and Observation Station

224
0. 8-r . GROUND GL-lin(G3) flMP=0.P2P Cklne]

SHAFT GL-7in(K3)

GROUND GL-48ni(G2)

flMP=0.157 Cklne]

0.4

0.4

flMP=0.356 Cklne]

-0.4

SHAFT GL-/18in(Kl)

J I I I 1 I L

flMP=0.l53 Cklne]

J I L 0

0.2-r

5 10

TIME C SEC ]

(a) Event No. 1 (Epicentral Distance 15 km)

GROUND GL-liii(G3) - flriP=0.202

1 5

C k Ine ]

SHAFT GL-7in(K3) nMP=o.09P Cklne]

-0.2

0. 1 -r GROUND GL-48in(G2) nMP=0.0d3 Cklne]

0. 1 0. 1 -r

-0. 1

SHAFT GL-zlSmCKl) flMP=0.04<5 Cklne]

I I I I I I I I I I I I I I I I

I I I I I I—I—I—I—I—I—I—I—

I

0 10 20

TIME C SEC ]

30

(b) Event No. 2 (Epicentral Distance 842 km)

Fig, 3 Comparison of EW Component Velocity Time Histories of the Shaft and Ground

225
XIO' FRQ=1.22CHZ) RRTIO= A. 67 .XIO* FRQ=2.10CHZ] RnTIO= 4.76

24(58

FREQUENCY C HZ ] 10 02468

FREQUENCY C HZ

]

(a) EW Component (b) NS Component

Event No. 1 Earthquake (Epicentral Distance 15km) -

XIO' FRQ=1,04CHZ] RnTI0=3.65 ,X10' FRQ=2,28CHZ] RRTI0=3.P0

24(58 FREQUENCY CHZ]

10 02468

FREQUENCY C HZ

]

(a) EW Component (b) NS Component

Event No. 2 Earthquake (Epicentral Distance 146km)

.XIO- FRQ=1.39CHZ3 RflTI0=4.03 .XIO' FRQ=2.21CHZ] RRTI0=3.17

2468

FREQUENCY CHZ]

10 02468

FREQUENCY CHZ]

(a) EW Component (b) NS Component

Event No. 3 Earthquake (Epicentral Distance 842Km)

Fig. 5 Horizontal Component Frequency Response Function of K3/G1

for Three Earthquakes

226
0.1A6

0.148

GROUND 0.172

SHAFT

GROUND

SHAFT

24(56 FREQUENCY C HZ 3 10 02468

FREQUENCY CHZ3

(a) EW Component (b) NS Component

Event No. 1 Earthquake (Epicentral Distance 15km)

GROUND O.iop _ , GROUND

SHAFT - SHAFT

2 4 6 8

FREQUENCY CHZD

(a) EW Component

10 2 4 d 8

FREQUENCY CHZD

(b) NS Component

Event No. 2 Earthquake (Epicentral Distance 842km)

Fig. 4 Comparison of Fourier Spectra from Shaft and Ground

10

Amplitude Ratio

0 12 3 4 Amplitude Ratio

0 12 3 4

Amplitude Ratio

0 12 3 4 5

I 00

(a) EW Component (b) NS Component (c) UD Component

Fig. 6 Spatial Distribution of Amplification Ratio for Three Component

of Shaft and Ground for Three Earthquakes

227

SEISMIC DESIGN METHOD OF SHIELD TUNNELS WITH

AXIAL PRESTRESSING BY MEANS OF RUBBER AND PC BAR

Katsumi Matsubara and Kazuhiko Urano

Technical Research Institute,

Hazama Corporation, Saitama, Japan

Abstract

This report proposes a method to introduce axial prestress to

the primary lining of the shield tunnel by using rubbers and PC

bars as the method for improving the axial seismic performance.

And the seismic effect of prestressing is verified by the axial

alternative loading test and by the calculation of the seismic

deformation method based on the analysis of the test results.

Introduction

During a large earthquake, a large axial tensile strain is introduced to a shield tunnel from the surrounding ground. This

tensile strain concentrates on the ring joints so that joints

plates deform plastically and the chance of water leakage is increased. As a countermeasure for this problem, a method for improving the axial seismic performance by introducing axial

prestress to the primary lining of the shield tunnel, can be considered . In this study, a method to introduce prestress to each ring

using PC bars by inserting rubbers between the segments is

proposed as a means for securing more improvement of the seismic

performance by this prestressing, and the effect of prestressing

is verified by the axial alternative loading test using a RC segment model. After that, the test results are analyzed and at the

same time, based on the results of the analysis, the response of

the shield tunnel is calculated by the seismic deformation

method

.

Concept of axial prestressing method

using rubbers and PC bars

Fig.l shows the concept of the axial prestressing method using

rubbers and PC bars. Using this Fig.l, this method is explained

as follows:

(1) Before introducing prestress, segment rings are assembled and

at the same time rubbers are inserted in grooves provided between

segment rings.

(2) The segment rings are prestressed every a ring by PC bars,

and rubbers are given a compressive strain until the ends of the

concrete segments come into contact. The purpose of bringing the

concrete segment ends to contact under the prestressed condition.

229
is to receive a jacking thrust during shield driving of excavation by means of the compressive reaction of the concrete segments . (3) When tensile strain is taken from the surrounding ground

during a large earthquake, this tensile strain is absorbed by a large compressive strain which was given to rubbers precedingly

by pres tress ing . Also, as the compressive strain is large enough,

the compressive stress will remain in the rubbers even during a large earthquake so to maintain the water cut-off performance.

Outline of the experiment

Purpose of the experiment

Purposes of this experiment are as follows:

(1) To verify that a large compressive strain can be introduced

to the rubbers that are between the rings using PC bars, and

using a full-scale RC segment model.

(2) To verify that, even for a tensile displacement corresponding

to the axial strain level (2.0x10-3) which can thoroughly cover

large earthquakes as well, the strain of rubbers between rings is

on the compression side and presents a large compressive reaction

to afford a high cut-off performance.

(3) To verify that, for similar large tensile displacements,

stress of PC bars is below the yield stress to secure the safety

performance of the PC bars.

Testpieces and loading apparatus used for the experiment

Fig. 2 shows the concept of the shield tunnel with a big diameter

which was supposed in the experiment.

Fig. 3 shows a general view of the RC segment testpieces used in

the experiment. Each of the RC segment testpieces was cut out

from a part of the primary lining between the 2 rings of the

full-scale shield tunnel in Fig. 2. The length of the segment in

the axial direction and the thickness of the primary lining were

set to be 1500mm and 650mm, respectively the same as those of the

supposed full-scale shield tunnel, giving consideration so the

same behavior as that of the full-scale structure could be obtained against an axial load.

Fig. 4 show the front view of the loading apparatus.

Table. 1 shows the specification of rubber, PC bar and testpiece

concrete used in the experiment.

Loading conditions

Loading conditions were given based on the following concepts:

(1) In pres t res s ing , prestress of 17tf per PC bar (57.4tf of

yield load) is introduced and, concrete ends are brought to contact by compressing a 38.5mm thick rubber by 8.5mm (5.7xl0"3 in

an average axial strain of the tunnel) which are adhered to

grooves between rings.

230
(2) After prestressing , each testpiece is left still for 24hrs to

converge stress alleviation of the rubber, and then 184tf of compressive force is acted and released to the testpiece, so to

simulate shield driving beforehand the loading test.

(3) The loading test is performed by an alternative loading of

the axial tension and compression. Incidentally, the maximum load

is set to be that before the yield of the PC bar.

Fig. 5 shows the loading cycle.

Measurement items

Major measurement items of the loading test include (1) relative

displacement of the joint, (2) rubber pressure, (3) total displacement, (4) change in prestress, (5) PC bar stress, (6) stress

of tensile reinforcing bars at rubber grooves.

Results of the axial alternative loading test

( 1) Load-relative joint displacement relationship

Fig. 6 shows the relationship of load and relative joint displacement. According to Fig. 6, a relative joint displacement 3mm

corresponds to the average axial tensile strain 2.0x10 and is

included within a smaller range compared with a compressive displacement introduced to the rubber by prestressing. Therefore, it

can be expected that the tensile strain acting from the surrounding ground during an earthquake can be thoroughly absorbed by the

compressive strain which was introduced before by prestressing to

the shield tunnel. Also, from the relative joint displacement between the rings showing a near linear behavior, it is understood

that the residual joint displacement is almost zero.

According to Fig. 6, a fact that the relative joint displacement

does not occur up to around lOtf of the tensile load can be considered, which is due to about lOtf of the prestress which was

introduced as a compressive strain into testpieces at the end of

prestressing. For this reason, contact of segment ends occurred

around 24tf despite the target prestressing load of 34tf.

(2) Load-axial displacement relationship

Fig. 7 shows the relationship of load and axial displacement. According to the figure, axial displacement presents almost the

same tendency as that of the relative joint displacement between

rings. From this fact, the axial displacement of testpieces can

be considered to have been caused by the relative joint displacement between rings.

(3) Load-PC bar stress relationship

Fig. 8 shows the relationship of load and PC bar stress. According to the figure, PC bar stress corresponding to average axial

tensile strain 2.0x10-3 is 5400kgf/cm2, and it is within the the

yield stress 10 , 500kgf /cm^ . From this fact, it can be understood

that the safety of PC bars can also be secured sufficiently even

during large earthquakes. Incidentally, the PC bar stress at the

start of the loading test after prestressing was 2 , 908kgf /cm^

.

(4) Load-rubber compressive stress relationship

231
Fig. 9 shows the relationship of load and rubber compressive

stress. According to the figure, the rubber compressive stress

corresponding to the axial average tensile strain 2.0x10"^ is

4.9kgf/cm2, indicating that a high water cut-off performance can

also be maintained even during large earthquakes. Also, the rubber compressive stress presents near-linear behavior, showing

that it returns to the initial value when the load is returned to

zero. Incidentally, rubber compressive stress at the start of the

loading test after prestressing is 9.5kgf/cm2.

Analysis of the results of axial alternative loading test

Outline of test results analysis

To calculate the axial seismic stress of the shield tunnel using

the seismic deformation method, the relationship of the axial

load and axial displacement is required. Here, based on the

results of axial alternative loading tests, a simplified axial

stiffness evaluation model is set for the shield tunnel with the

axial prestressing. And, through comparison with the test results

in terms of axial displacement, relative joint displacement, PC

bar stress and rubber compressive stress, the applicability of

the model is studied.

Estimation of elasticity modulus of rubber

on the compression side

The elasticity modulus of rubber is estimated from the

pr e s t re s

s - r e 1 a t ive joint displacement relationship and the

prestress-rubber ' s compressive stress during prestressing. First

the target value of the rubber's elasticity modulus was set at

75kgf/cm2, but is was not possible to estimate the influence of

the rubber's shape effect to the elasticity modulus correctly, so

the estimation of the elasticity modulus is done from test

resul ts . From an average value of the rubber's compressive stress

(measured by an earth pressure gauge) at a time point when both

relative joint displacement cg and rubber's compressive stress

<7 G become almost fixed (which vary only slightly) during

prestressing (at 24.2tf of prestress), elasticity modulus Eg of

rubber are determined as follows:

EG=(TG/eG= 10.33/0.194= 53.2kgf/cm2 (1)

Fig. 10 shows the result of the above-mentioned calculation. The

figure shows that the calculation value and experiment value

nearly correspond with each other. Therefore, Eg= 53.2kgf/cm2 is

used as the rubber's elasticity modulus for the results of the

following studies.

Study on axial alternative loading test

(l)Model of axial stiffness evaluation

232
It is assumed that the segment ends come into contact at a prestressing force Po during pres tress ing , and that prestress is introduced to Ppc. Also, it is assumed that the rubber's compressive stress will not increase after the contact of segment ends • In this case, as the axial stiffness models representing the

contact and non-contact of segment ends, the ones shown in Fig. 11

are considered. That is, for the contact of segment ends, a model

consisting of the concrete segments and PC bar springs as parallel springs. Also, for the non-contact of segment ends, a model

consisting of segments and rubbers springs connected serially and

PC springs are assembled in parallel with the former, and these

are considered.

(D Equivalent axial stiffness

An axial force Po at the contact of segment ends is determined

by the following formula:

Po= ap Ap- ctgAg (2)

Where, ap: PC bar stress at the start of the test

Ap : Sectional area of PC bar

G : Rubber copressive stress at the start of test

Ag: Sectional area of rubber

When the acting axial force P is equal or less than Po (When P ^ Po), the equivalent axial stiffness (EA)eq^ is obtained as

f ol lows

:

(EA)eq^= E s A s +

1 E p A (3)

Where, Es

As

Is

Ep

Ip

When P ^ Po,

(EA)eq =

Elasticity modulus of segment concrete

Sectional area of segment concrete

Length of segment concrete

Elasticity modulus of PC bar

Length of PC bar

(EA)eq" is obtained as follows:

+ EpAp

1 +

E s As 1 1 (4)

Where , Eg

I'G Re lat ionship

When P ^ Po : P = ( E A )

When P ^Po: P = ( E A )

E G A G 1 s Elasticity modulus of rubber

Length of rubber

of load and axial displacement

eq

eq

Is

6

Is

I- P o { 1 - ( E A) e q

( E A) eq

(5)

(6)

Where, 6: axial displacement

This relationship is plotted as shown in Fig. 12.

(3) PC bar stress and rubber's compressive stress

An increment of PC bar stress A ap by loading are

233
determined as follows:

When P^Po: A a p = Ep , ^ f (7)

When P^Po: Aap= -f^Ep { , ^ ^ ^

. + ^ ^ ~ f

^

} (8)

IP ( E A) eq' ( E A) eq"

And a decrement of rubber's compressive stress A (^oby loading

are determined as follows:

When P ^ Po : A a G = o ( a G = c on s t ) ( 9 )

When P^ Po: A G =^^^-^ „{ ^ \ , }(10) A G ( E A ) "

J ^

E s A s 1 G E G A G i s (2) Specification and calculation conditions of test materials

The specification of test materials is shown in Table. 1. Incidentally, prestress Ppc , PC bar stress cr p and rubber's compressive stress a G at the start of the alternative loading test are

as follows

Ppc= 34.2 (tf)

(Tp= 2,787 (kg/cm2)

a G= 8.8 (kg/cm2)

Therefore, Po is determined by formulas (2), as follows:

Po= 11.29 (tf)

(3) Comparison of experiment results and calculation results

0 Equivalent axial stiffness

The calculation formula of the equivalent axial stiffness is

obtained using formulas (3) and (4). Table. 2 shows the comparison

of calculation value and experiment value about equivalent axial

stiffness

.

(2) Relationship of load and axial displacement

The load-axial displacement relationship obtained from experiment results is shown in a solid line in Fig. 7. Also, the calculation values by formulas (5) and (6) are shown in the same

figure using broken lines, for a comparison with experiment

values. Likewise, the load-relative joint displacement relationship is shown in Fig. 6.

(3) PC bar stress and rubber's compressive stress

The load-PC bar stress determined from the experiment results

is shown in Fig. 8 using a solid line. Also, calculation values by

formulas (7) and (8) are shown in the same figure using broken

lines, for comparison with experiment values.

Likewise, the load-rubber's compressive stress relationship is

plotted in Fig. 9 using values calculated by formulas (9) and

(10).

Calculation of seismic stress

by the seismic deformation method

234
Analysis method

The seismic deformation method determines the maximum crosssectional force generated in the tunnel, supposing that the tunnel is a beam on an elastic floor supported by a ground spring,

and giving a ground displacement (supposing the distribution of

axial displacement of the tunnel as a sine curve) for the tunnel

depth to the spring end. A conceptual view of the analysis model

by seismic deformation method is shown in Fig. 13.

Analysis conditions

(1) Velocity response spectrum used for the seismic deformation

method

A velocity spectrum Sv necessary for calculating the response

displacement is set by the following formula, based on an acceleration spectrum Sa shown in Fig. 14:

SA(T,h)-T

Sv(T,h)= (11)

2

Where, T: Natural period, h: Damping coefficient

(2) Analysis cases

In calculating, specifications including the elasticity modulus

of segments and rubber are set to be the same values in the test.

With an aim to study the response characteristic of the tunnel,

depth, diameter, etc. of the tunnel are varied, and 8 cases are

shown in Table. 3 and the analysis models in Fig. 15. In this

analysis , 5 G / 1 G = 0.2 and Ip/ls = 0.9.

Where, 6 g : Decrement of rubber's length by prestressing

Analysis results

Under the above-mentioned analysis conditions , the seismic

response analysis of the shield tunnel is performed. The

analysis results are shown in Table. 4.

From the table, the following can be concluded:

(1) According to the analysis results performed under these conditions, PC bar stress is within the yield stress

( 10 , 500kgf /cm^ ) , and the safety of PC bars is secured.

(2) For stress generated in rubbers as well, all cases present

compressive stress.

(3) For relative joint displacement. Case 3 with a smaller

diameter and smaller thickness of lining presents the largest

value (1.28mm). It is because an axial stiffness of the tunnel

was smaller than ground stiffness, and that increased the transfer ratio of ground displacement.

(4) For the compressive stress of rubber inserted between segments. Case 8 with smaller rubber thickness presents the largest

drop of stress at maximum tension. It is because, while relative

joint displacement is slightly smaller in Case 8 than in Case 3

235
where it is the largest, the smaller rubber thickness increased

the drop of stress in the same relative joint displacement.

(5) For PC bar stress, stress at maximum tension is the largest

in Case 5 where the rubber's cross-section area increases. It is

because a larger PC bar stress was required in giving the same

compressive displacement to the rubber during prestressing

.

Conclusions

In this study, the following can be summarized.

(1) From the results of the experiment, it is possible to absorb

the axial tensile strain supposing a large earthquake by compressive strain of rubbers introduced by prestressing within the

yield stress of the PC bars. Also, for axial tensile strains up

to 2.0xl0"3 or so as well, rubbers can keep their high compressive stress to afford a high water cut-off performance.

(2) For the contact of segment ends, a proposed model is consisting of the concrete segments and PC bar springs as parallel

springs. Also, for the non-contact of segment ends, the model is

consisting of segments and rubbers springs connected serially and

PC springs are assembled in parallel with the former.

(3) From the results of the seismic response analysis by the

seismic deformation method, the effect of prestressing like (1)

can be verified.

Future Directions

After this report, the following will be researched.

(1) We will progress in studying the response characteristics of

the shield tunnel by the seismic deformation method, and make the

chart of the structural design based on the conclusion of the

seismic response analysis.

(2) We will investigate the maximum water pressure at which the

water cut-off performance can remain by prestressing on condition

that the relative joint displacement happens by the experiment.

(3) We will verify the applicability of this proposed method by

introducing prestress to the shield tunnel on site in order to

make the method the practical use.

Acknowledgement

This research is conducted as a part of the Comprehensive Research Project ''Technology Research and Development Regarding

Use of Underground Space ( The Cooperative Research in Development of Seismic Design of Underground Structure)''. The authors

wish to thank all members of this Comprehensive Research Project

for their advice in the preparation of this paper.

236
References

1. Kawashima , K . , Obinata,N., Shiba,Y., Kanou,T., rSeismic Resistant Design Procedure of Shield Tunnels, Part 1, Application of

Seismic Deformation Method Based on Equivalent Stiffness of

Shield Segments, No. 2262, Technical Memorandum of PWRI , 1985

2. Arakawa,T., Kawashima , K .

, : Determination procedure of input

ground motions for earthquake response analyses of structures,

Civil Enginering Journal, Vol.26, No . 3 , pp. 126-131, 1984

237
Joi nt displacement

Rubber JL

Segment

PC bar

\ \

Contact of the segment ends

Joi nt

di sp I acement

V//

1

Compressive stress remain

(Water cut-off performance remain)

Before Prestressing After prestressing Dur i ng a I ar ge Ear t hquake

(Tensi le strain 2.0x10"^)

Fig.1 Concept of the axial prestressing method

using rubbers and PC bars

PC bar <i> 26

3911 651|

NTrimn ! Ill

1

iiil

1 1 1 1 1 -rri I

Dr i vi n9 di r ect 1 on

Primary lining

Outer dianetsr 13900 nn

Inner diameter 12800 nm

Ihi ckness 650 mm

Sectional area 27.057 m'

Length 1500 mm

E 1 aat i ci ty itodul U9 3.75xlO« tf/cm'

Fig. 2 Concept of the shield tunnel with a big diameter

which was supposed in the experiment

238
h9

1500 1500

Rubber

Plate PC bar

Plate for ViiO

PC anchor age \^

^^jS. A.

Detailed drawine of A

M - 2 6 - 2 0

S B P B 6 6 / 1 1

21 \e;2BXI3Bxl

Concr ete seement

Fig. 3 General view of the RC segment testpieces

used in the experiment

Reaction beam (fixed) 3502S isoo

\

Support

Testpiece 650x1300x1500

1500 25350

Reaction beam (movable)

Center hole Jack

Fig. 4 Front view of the loading apparatus

Table 1 Specification of materials

used in the experiment

Material Specification

Natural

rubber

Hardness (deg.) 41

Thichness (mm) 38.5

Kidth (mm) 80

Dianeter (mm) 26

PC bar (type B)

Length (mm) 2184

Yield stress (kgf/cm') 10500

Elastici ty modulus (kgf/cmM 2.075X10'

Compressive strength (klf/cm') 434

Concrete Elasticity modulus (kgf/cm') 3.12X10'

lensi le strength (kgf/cm') 32.4

-50 tf

Fi g.5 Loadi ng cycle

95 tf

239
Calculation value

Calculation value

10.0

I

Fig. 6 Load-relative joint displacement Fig. 7 Load-axial displacement relationship

r e I at i onsh i p

Calculation value

Fig. 8 Load-PC bar stress relationship Fig. 9 Load-rubber compressive stress relationship

240
"e 1 2

-

Relative joint displacement (mm)

Fig. 10 Rubber compressive stress

- relative joint displacement relationship

Segment spring

r-A/WV\An

EsAs

Segment spring Rubber spring

I—VWWW— —

I

EsAs EgAq

Is I 0

I—AWW^

PC bar spr i ng Ep Ap —WWWPC bar spring

Ep Ap

Contact of segment ends

( P ^ Po )

Non-contact of segment ends

( P ^ Po )

Fig. 11 Axial st i f f ness m o de

I

Load P

Table 2 Equivalent axial stiffness

Calculation

value

Exper i mena

1

va 1 ue

( E A) '

( Contact of segment ends ) 2.67X10' 1.69X10*

(E A) „"

( Non-contact of segment ends ) 3 .8 0 X 1 0' 3.61X10'

( t f

)

Fig. 12 Load-axial displacement relationship

241
Propagation direction

g. 13 Concepti onal vi ew

of the analysis model

by seismic deformation method

0.1 0.20.30.50.71 2 3

Natural period T (sec)

Fig. 14 Acceleration response spectral curve

Fig. 15 Ana 1 y si s mo de I

242
Table 3 Analysis cases

No. I 1L

1

0

k i;0

c

0 7 00

Di ameter D(ffl) tR n R n 0 . u 1R n 1R n tR n 1 R n 1 U . u

1 R n 1 0 . u

Thickness of 1 ining D,(m) n Q u . 0 n D ft 1 n 0 ft 0 U.B ft 0 0.8

Depth Z(m) 9ii n. u OR ft OR ft OR ft OR ft OR ft

Tunnel Ar/A, (xio-^) 1 .25 1 .25 1 .25 1 71 1 7'i

Ag/A, 0.25 0.25 0.25 0.25 0.50 0.25 0.25 0.25

Pp 0 /Pp oo 1.2 1.2 1.2 1.2 1.2 1.5 1.2 1.2

Thickness of rubber lo (mm) 38.5 38.5 38.5 38.5 38.5 38.5 38.5 26.0

Surface

layer

S wave velocity Vs(m/s) 200 200 200 200 200 200 100 200

Unit weight rt(t/n') 1.8 1.8 1.8 1.8 1.8 1.8 1.6 1.8

Table 4 Analysis results

No. 1 2 3 4 5 6 7 8

Introduced force for prestress Ppc(tf) 1219.4 1219.4 171.5 1219.4 2439.8 1524.3 1219.4 1219.4

Maximum compressive axial force Pi(tf) -23504.0 -10208.0 -8925.1 -23352.0 -23351.0 -23336.0 -16412.0 -23484.0

Maximum compressive axial force Pii(tf) 108.1 583.9 183.9 1631.4 1385.1 1378.0 970.5 1133.0

Maximum compressive strain (XIO-") ei

-1.945 -0.849 -5.276 -1.942 -1.941 -1.940 -1.364 -1.952

Maximum tensi le strai

n

(XIO-") £11

6.777 2.948 8.542 5.969 6.557 6.741 5.926 6.690

Stress under the maximum compressive

force Os'=P'/As(tf/m^)

-615.3 -267.2 -1611.4 -611.3 -611.3 -610.9 -426.6 -614.8

Stress under the maximum tensile

force as"=P"/As(tf/m2)

28.3 15.3 34.2 42.7 36.3 36.1 25.4 29.7

PC bar stress under the maximum compressive force ap'(tf/m^)

21031.0 23579.0 13371.0 8332.7 46596.0 27447.0 22390.0 21035.0

PC bar stress under the maximum

tensile force crp"(tf/m*)

41160.0 32333.0 45189.0 26529.0 66236.0 47462.0 39189.0 40960.0

Rubber stress under the maximum compressive force aG'(tf/m^)

-106.4 -106.4 -106.4 -106.4 -106.4 -106.4 -106.4 -106.4

Rubber stress under the maximum

tensile force (Ja''(tf/m*)

-92.4 -100.3 -88.8 -94.

r

-92.9 -92.5 -94.2 -86.0

Relative joint displacement ffnCmm) 1.02 0.442 1.28 0.895 0.987 1.01 0.889 1.00

243

Seismic Isolation For Underground Structures

K.Ono, S.Shimamura and H.Kasai

Dept. of Civil Engineering, Konoike Construction Co., Ltd.

3-6-1, Kitakyuhoji-machi, Chuo-ku, Osaka 541 Japan

ABSTRACT

Underground structure such as shield tunnel, shaft, pipe line, etc. strains during

earthquakes due to deformation of the surrounding ground. Ground strain caused by earthquake in

soft subsurface layer or interface between two different layers with large difference in stiffness is easy to be amplified. Therefore, it should be taken a great care for underground structures to be

constructed in such a ground.

First of all, this paper introduces a technique of seismic isolation applied to a shield tunnel

under the sea bed. Then, the authors present a unique and yet reasonable idea to protect shield

tunnel or shaft from large strain during earthquakes. The idea is to enclose a shield tunnel and a

shaft entirely by a cushion material. This cushion is expected to absorb strains mobilized by the

deformation of the surrounding ground during earthquakes. The effect of the cushion was

evaluated analytically for a shield tunnel £ind its shaft.

INTRODUCTION

Use of underground space has been attracted in Japan to supply additional land. In

particular, underground space in metropolitan areas is getting more precious due to high cost of

land caused by concentration of population. However, since underground in metropolitan areas

already contain many facilities, deeper part of the ground in these areas has to be utiUzed.

Underground space in metropolitan areas has been mainly used for shopping malls,

parking lots, lifelines of electricity, gas, telecommunications, water supply or drainage. It has been

also used for subway system or flood control system. Demand for usage of underground space is getting larger and larger.

Therefore, construction of shafts and shield tunnels will also continue to increase. Since

the ground in Japan is very complicated in general, shafts and tunnels sometimes have to be

constructed through an interface zone between two different layers such as soft alluvium and hard

diluvium. Large strain concentration occurs in such zone during earthquakes. It would be one of

the effective techniques to isolate structure from the surrounding ground by a cushion material and

to absorb seismic strains by this material. This absorption of seismic strains would result in the

increase of the seismic resistance of the structure.

APPLICATION OF SEISMIC ISOLATION TO SHIELD TUNNEL

In the last two decades, the authors have been engaged in seismic design of shield tunnels

and their shafts constructed in various ground conditions. Through these experiences, it has been

clarified to be more practical to adopt seismic isolation for these structures in stead of strengthening

themselves. Following are examples of seismic isolation applied to a shield tunnel.

245
Seismic Isolation by Elastic Washer

When seismic wave applies to a shield tunnel as shown in Figure 1 , compressive and

tensile strain and stress are induced into the tunnel. Compressive stress is normally within a level

of the strength of the tunnel itself. However, tensile strain caused by the level of design earthquake is easy to exceed the

limiting value of the tunnel, particularly with reinforced concrete segment. Excess of tensile strain

has to be absorbed by joints of the tunnel. If joint of a shield tunnel is subjected to tensile strain,

the connecting bolts and plates of the joint box are easy to be damaged. Therefore, leaking water

from the joint and local failure of the tunnel would cause functional problem in the tunnel after the

earthquakes.

Figure 2 shows a shield tunnel constructed under the sea bed. According to the results of

the seismic analysis of the tunnel subjected to the earthquake of 150 gal at the base ground of op200m, joints bolts longer than 50 cm are required for the tunnel. The diameter of the bolts adopted

in the analysis is 24mm and this size is minimum allowable in terms of fastening the bolt in the

construction. Therefore, length of 50 cm is minimum requirement. However, this length is too

long to install. If flexible segments through which longitudinal movement is free is adopted, they have to be installed at the interval of every 10 to 20 m. Since flexible segment is very expensive in

general, adoption of a large number of flexible segment will result in very high cost of the

construction. However, very high strain concentration occurs at the joint of shield tunnel and the

shaft due to the rocking behavior of the shaft and different vibration mode of the tunnel and shaft. Therefore, flexible segment as shown in Figure 3 was installed at the joint.
l:i 00 m

P+ 1.50

2,130m 13.60m

P- 33.20

(a) Geologic Pronie

RCsegment

Gas ripe('/>750mm)

RCsegment ; B=900inm,li=200mm

Ringejointbolt; 16-M24

Invert Concrete

Unit = mm

(b) Tunnel Section

Figure 2 Section of the Shield Tunnel

Primary Water Proof Rubber

zSecondary Water

Pr-oof Rubber

1^ "n"

Durable Sleeve L I / Inner Covering Rubber

(a) Contraction

(b) Extension

Flexible Segment

(c) Shear

Figure 3 Flexible Segment

247
In order to overcome above problems, the authors developed new type of washer called

"KRS elastic washer". KRS washer is installed between joint plate and nut of the connecting bolt as shown in Figure 4. The KRS washer adopted for the tunnel is a ring type with 4) 26 mm of inner diameter, cj) 44

mm of outer diameter and 13 mm of thickness as shown in Figure 5. This washer mainly consists

of epoxy resin. It is very easy to select a specified Young's modulus and yielding strength of the

washer by adjusting the content of epoxy resin and the hardener. For this tunnel, 250,000 tf/m2

of Young's modulus and 12,000 tf/m2 of yielding strength are chosen for the washer. Figure 6

shows the stress-strain curve of the washer.

According to the results of seismic analysis of the tunnel with KRS washer installed at each

joint, the bending stress of the plate at the joint is found to reduce almost proportional to the

reduction of the longitudinal stiffness. In this case, the bending stress reduces to one third of the

value induced in the plate without KRS washer. The tunnel is found to be safe against the design

earthquake. Experimental verification was carried out to check the effect of KRS washer in

reduction of the longitudinal stiffness using model tunnel. Model of the tunnel consist of 5 rings

and is identical with the real tunnel except for the nonexistence of the surrounding soil. Figure 7 shows the model and experimental set up. The tunnel is made of ductile

segments. The outer diameter is 5.4 m and the height is 5.0 m. Axial tensile force was applied to the model by 12 jacks set at the top of the model. Most of the measurements were focused on the

middle ring to avoid local effect which might be induced into the boundary rings.

Figure 8 shows obtained force-elongation relationship for the model with and without KRS

washers. In this case, about 40% of the reduction in tensile longitudinal stiffness was observed by

the use of KRS washers.

Therefore, same amount of tensile force reduction is expected at each joint of the actual

tunnel if KRS washers are used.

KRS washer is also expected to be adopted in the construction of Trans-Tokyo Bay

Highway. In this case, the size of the KRS washer will be the order of the size shown in Figure 9.

;i|

rigure 4 Seismic Isolation Figure 5 The KRSwasher

Using KRSwasher u^^^ die Tunnel

248
0)

l-i &,

S

oU

10 lO 30 40 50

Strain (%)

Figure 6 Stress-Strain Curve of KRSnasher

Figure 7 Model of the Tunnel

300

without KRSwasher with KRSwasIier

(|)77

NS^Piain Washer^

;i;^KRSwa$ller;S^

Elongation of the Middle Ring (mm) Plain Washer

CM

o

CO

00

CO

CD

Unit = mm

Figure 8 Tensile Force-Elongation Curve Figure 9 KRSwasher for

Trans-Tokyo Bay Highway

249
SEISMIC ISOLATION BY CUSHION MATERIAL

KRS washer is not capable of reducing a large strain arisen at such a particular zone of the

interface between soft ground and hard ground within the limiting value of the tunnel. Similar

strain concentration occurs in shaft at such interface zone. In these cases, enclosure of the shaft or

the tunnel by soft cushion material would be one of effective methods to release large seismic strain as shown in Figure 10.
Case Study for Shaft

Figure 11 shows an outline of a shaft employed for the case study. The shaft of

reinforced concrete is 10m in diameter, 90m long and its wall thickness is Im. Seismic analysis

is also done for the case without the isolation layer and the case where the ground is uniform to be

alluvial clay. The isolation layer is 0.5m thick and its Young's modulus is 20 tf/m2. This isolation

layer is covering the shaft for 20m.

Three-dimentional axisymmetric finite element method is employed for the response

analysis. Figure 12 shows the finite element model. Material properties of the shaft, the ground

and the cushion material are shown in Table 1. Figure 13 and 14 show input accelerogram with

the maximum acceleration of 126.2 gal on the model base of GL-lOOm and its velocity response

spectrum, respectively. In the analysis, the damping factor of each mode is assumed to be 10%.

Figure 15 shows the calculated maximum bending stresses and maximum shear stress arisen in the shaft. According to the case study, large stress concentration occurs in the shaft

around the interface zone. The stress concentration factor reaches about 3.5 in this case. Bending

stresses both in concrete and steel bars will surpass their limiting values although the shear can be

supported easily by installing stirrups. The cushion isolation reduces the stress concentration by

20%, which is not so sufficient.

However, this case study indicates that such a cushion isolation could be come more

effective if more rational installation and more effective material are developed.

CDO

CD

Ln

E

CD

il £

ITT

CD

= lOm

77? Alluvial Clay

r = 1.5 cf /m'^

m

V. = 50m/s

Cushion Material (t=0.5m)

777

Diluvial Sand

• T = 2.Q t:f /m^

Vj = 200nn/s

Rigid Base

Figure 11 Ground and Shaft Profile

251
0.0

5U.0

00.

0

L

5.0m

73

co

CO

395 nodes

360 elements

E00

i5om

Figure 12 Finite Element Model

Table 1 Material's Properties

Properties Alluvial

clay

Diluvial

sand Shaft

Cushion

Material

Unit Weight (tf/m3) 1.5 2.0 2.5 1.8

Young's Modulus (tf/m2) 1,140 24,300 3,000,000 20

Poisson's Ratio 0.49 0.49 0.167 0.49

252
150.0

13

I'

0.1 1 10

Period (sec)

Figure 14 Velocity Response Spectrum of Input

Accelerogram on the Model Base

253
without seismic isolation

with seismic isolation

uniform ground (Ac) without seismic isolation

Bending Stress (tf/m2) Shear Stress (tf/m2)

Figure 15 Maximum Bending and Shear Stress along Shaft

Case Study for Shield Tunnel

Figure 16 shows a tunnel and two different ground layers employed for the case study.

The tunnel is composed of 0.4m thick reinforced concrete segments and the diameter is 10m.

The tunnel is modeled as beam elements and the surrounding ground is modeled as lumped

mass springs. Interaction springs are also installed in the model to link the ground masses and

tunnel beam elements . The analytical model is shown in Figure 17. The cushion material

covering the tunnel for 40m in the diluvial layer is expressed by spring elements. Young's

modulus of the cushion is assumed to be 1/100 of the value of the diluvial sand. Input data for the

tunnel and the ground are shown in Table 2 and Table 3, respectively. Same seismic load as used

in the analysis of the shaft is also employed in this study. Properties of accelerogram are shown in

Table 4. The time history analysis is done by the direct integration method. Damping factor of

each mode is assumed to be 10%.

Figure 18 and Figure 19 show the calculated maximum axial force and bending moment

arisen in the tunnel. The cushion isolation reduces their peak values by about 30% in this case. Larger reduction effect could be possible by increasing the thickness of cushion and using

appropriate cushion material.

Installation of such cushion isolation is also big problem to be solved. Figure 20 and 21

show rough idea of installation. For tunnel, cushion material made by mixing liquid agent with

hardener is injected between outer surface of the tunnel and the ground through the grouting hole.

For shafts, seismic isolation cushion as mat state is installed together with the reinforcing bar cage

of the diaphragm wall.

254
/// ///

Alluvial L-lay Dilu vial Sand

r = 1.5 tf /m'' r = 2.0 Cf /m-'' Vs=50m/s 150m/s

E

o 1

( 0

/10m ^ \ MOm

Cushion Material

Rigid Base

Figure 16 Ground and Tunnel Profile

Figure 17 Analysis Model

255
Table 2 Properties of the TunFiel

Unit Weight (tf/m3) 2.5

EA (If) 1,810,000

EI (tfm2) 41,800,000

Table 3 Properties of Ground Masses

Properties Alluvial Clay Diluvial Sand

Interval between , s Ground Masses ' 4.0 10.0 20.0 4.0 10.0 20.0

Mass m (tfs2/ni/m) 24.8 62.0 124. 33.1 82.7 165.

Klx.Kly (tf/m/m)

c

• K2x (tf/niym) Spnng ^ ' Constants K2y (tf/m/ni)

K3x,K3y {iilmJm)

4,600

11,500

3,880

61.2

11,500

4,620

1,550

153.

23,000

2,310

776.

306.

55,100

134,000

46,500

783.

138,000

55,500

18,600

1,850

275,000

27,800

9,300

3,700

These parameters refer to Fig. 17

Table 4 Parameters of Input Earthquake Motion

Parameters

Axial Force

Calculation

Bending Moment

Calculation

Superficial Ground Alluvial

Clav

Diluvial

Sand

Alluvial

Clay

Diluvial

Sand

Maximum Response of , . the Ground Surface 0.0688 0.0228 0.0973 0.0323

Wave Length (m) 453 325 320 230

Input Max. Acc. , of the Model Base ^^aij 282 353 367 453

256
2.000

1,500 -

0)o

iu

-a<

-without seismic isolation

I with seismic isolation

Alluvial Clay 0 Diluvial Sand

Distance from the Interface (m)

Figure 18 Maximum Axial Force of Tunnel

5,000

4,000

§ 3,000

B

o

I 2,000 \-

^ 1,000

4,929 (1.00)'

3,347 (0.68)

Cushion Material

without seismic isolation

I with seismic isolation

Alluvial Clay 0 Diluvial Sand

Distance from the Literface (m)

Figure 19 Maximum Bending Moment of Tunnel

500

257
258
CONCLUSIONS

Large stress concentration occurs at the joint of shield tunnel itself or at the joint of tunnel

and the shaft during earthquakes. These stress concentration will be released by the installation of

the proposed elastic washer and installation of flexible segment. Particularly, installation of the

elastic washer is very efficient technique to release the longitudinal tensile strain of the tunnel since

the washer is relatively inexpensive and it is easy to install. At an interface zone between two different layers with large difference in stiffness, larger

stress concentration occurs so that it can not be released by the technique of elastic washer or

flexible segment alone. Enclosure of the tunnel or shaft by cushion material at near the interface zone looks effective to release the stress concentration. This technique should be discussed more

before getting into the practical use.

FUTURE DIRECTIONS

Use of elastic washer Uke KRS and cushion isolation could improve the seismic resistance

of shield tunnel and the shaft. Therefore, improvement and development of these techniques

should be done as the future works. Installation technique of cushion isolation should also be

studied. Effect of combined use of KRS washer and cushion isolation should also be examined.

ACKNOWLEDGEMENTS

This study was conducted as a part of study on "A Cooperative Research in Development

of Seismic Design of Underground Structures" in "Technology Research and Development

Regarding Use of Underground Space" of "A Comprehensive Research Project". The authors

wish to express their thanks and appreciation to Dr. Kawashima, Public Works Research Institute,

Ministry of Construction and to the cooperative research colleagues.

refp:rences

1) PWRI, ACTEC, Okumura Corporation, Kajima Corporation, Konoike Construction

Corporation, Shimizu Corporation, Taisei Corporation, Tobishima Corporation, Hazama

Corporation, Fujita Corporation, "Development of Seismic Design of Underground Structure",

Cooperateve Research Report of PWRI, 1991.

2) Tamura, C, S.Okamoto and M.Hamada, "Dynamic Behavior of a Submerged Tunnel during

Earthquakes", Report of Institute of Industrial Science, Univ.of Tokyo, Vol.24, No.5.

259
1
V. SEISMIC RISK ANALYSIS

Performance of AWSS and PWSS of San Francisco

During and After Loma Prieta Earthquai<e"

M.M. Khater, C.R. Scawthorn, T.D. O'Rourke, F. Blackburn

"Seismic Reliability Analyses of Large Scale

Lifeline Networks Taking into Account

The Failure Probability of the Components"

T. Sato, K. Toki

"Earthquake Damage Analysis on

Telecommunication Conduits"

K. Yagi, S. Mataki, N. Suzuki

"Regional Risk Assessment of Environmental

Contamination from Oil Pipelines"

S.D. Pelmulder, R.T. Eguchi

'Damage Assessment of Lifeline Systems in Japan"

M. Hamada

261
i
PERFORMANCE OF AWSS AND PWSS OF SAN FRANCISCO

DURING AND AFTER LOMA PRIETA EARTHQUAKE

M.M. KHATER

PRINCIPAL RESEARCH ENGINEER, EQE, INC. SAN FRANCISCO, CA

C.R. SCAWTHORN

VICE PRESIDENT, EQE, INC., SAN FRANCISCO, CA

T.D. O'ROURKE

PROFESSOR, CORNELL UNIVERSITY, ITHACA, NY

AND

F. BLACKBURN

FIRE PROTECTION CONSULTANT, SAN FRANCISCO, CA

ABSTRACT

The performance of the Auxiliary Water Supply System (AWSS) and the Portable Water

Supply System (PWSS) of San Francisco following the 1989 Loma Prieta earthquake is discussed in this paper with reference to the initiation and suppression of the fire in the

Marina. The computer program GISALLE (Graphical Interactive Serviceability Analysis

of LifeLines for Engineering) is used to simulate observed damage to water mains and

hydrants immediately after the earthquake. The results of the computer program,

GISALE, are compared with actual performance, and recommendations are made for

improving AWSS reliability.

263
INTRODUCTION

The October 17, 1989 Loma Prieta earthquake (Ms 7.1) was the largest event to occur in

northern California since 1906. This event demonstrated that earthquakes can still cause

severe damage to modern urban areas - although only few building were actually

destroyed, major lifelines and vital services were lost. The critical importance and seismic

vulnerability of utility systems was strongly emphasized in the Loma Prieta earthquake.

In order to understand this vulnerability this paper briefly describes the damage and

performance of the San Francisco Auxiliary and Portable Water Supply systems, during

the Loma Prieta, earthquake. A graphical interactive computer program GISALLE

(Graphical Interactive Serviceability Analysis of LifeLines for Engineering) has been used

to simulate the Performance of the Auxiliary Water Supply System (AWSS) of San

Francisco during the Loma Prieta earthquake.

SYSTEMS DESCRIPTION

Auxiliary Water Supplv System (AWSS): The AWSS is one of only a few high pressure

system of its type in the U.S. It is separate and redundant from the municipal water

supply system (MWSS) of San Francisco, and is owned and operated by the San Francisco

Fire Department (SFFD). It was built in the decade following the 1906 San Francisco

earthquake and fire, primarily in the north-east quadrant of the City (the urbanized

portion of San Francisco in 1906 and still the Central Business District), and has been

gradually extended into other parts of the City, although the original portion still

constitutes the majority of the system.

The AWSS supplies water to dedicated street hydrants by a special pipe network with a

total length of approximately 125 miles of buried pipe, with nominal diameters ranging

from 10 - 31 inches. Nearly 100 miles of the system is cast iron, to which about 25 miles

of ductile iron pipe have been added during the past several decades. The system, which

is shown in Figure 1, is intended to augment the city's existing fire fighting capacity by

providing a supplementary network that would work independently of, and in parallel

with, the MWSS. It is separated into upper and lower pressure zones. Each zone operates

nominally at a pressure of about 150 psi, which is approximately 2.5 times the pressure in

the municipal system.

264
The main source of water for the AWSS system under ordinary conditions is a 10 million

gallon reservoir centrally located on Twin Peaks, the highest point within San Francisco

(Figure 2). Water from this source supplies two zones: the Upper Zone, and the Lower

Zone where the pressure is controlled at Ashbury Tank (0.5 million gallon) and Jones St. Tank (0.75 million gallon) respectively.

The Twin peaks reservoir supply may not be adequate under emergency conditions. Two

pump stations exist to supply water from San Francisco Bay (each has four diesel pumps)-

Pump Station No. 1 is located at 2nd and Townsend Streets, while Pump Station No. 2 is located at Aquatic Park - each has 10,000 gpm at 300 psi capacity. Both pumps were

originally steam powered but were converted to diesel power in the 1970's. The pipe

network has five manifold connections along the City's waterfront, in order to permit the

City fireboat Phoenix to act as an additional "pump station", drafting from San Francisco

Bay and supplying the AWSS. The Phoenix's pump capacity is 9,600 gpm at 150 psi.

Lastly, in addition to the above components, San Francisco has 151 underground cisterns,

again largely in the northeast quadrant of the City These cisterns are typically of

concrete construction (a few are brick and predate the 1906 earthquake) 75,000 gallons

capacity (about one hour supply for a typical fire department pumper) and are located at

street intersections, accessible by a manhole. They are highly reliable and extremely low

maintenance. The cisterns are completely independent of all piping and are filled by hose

by fire department pumpers supplied from hydrant. In the event of water main failure,

water may be drafted from these cisterns via the manhole. In 1986, due to a recognition

that these cisterns are mostly only in the northeast quadrant of the City, a bond issue was

passed for construction of an additional 95 cisterns, in outlying portions of the City.

Control of the AWSS is centered at Jones Street tank house, where gauges provide pressure

readings at a limited number of locations in the network. A limited number of gate valves can be remotely operated from Jones Street tank house via land lines, the Lower Zonepressure can be increased by opening valves at the tank house, and the Twin Peaks

pressure Zone-can be "cut-in" by remotely operating valves located at Ashbury tank.

However, many other gate valves in the system must be operated manually.

In 1906, San Francisco had sustained major ground failures (leading to water main breaks)

in zones generally corresponding to filled-in land and thus fairly well defined. Because it was anticipated these ground failures could occur again, these zones (termed "infirm

areas") were mapped and the pipe network was specially valved where it entered these

265
infirm areas. Under ordinary conditions, all of the gate valves isolating the infirm areas

are closed, except one, so that should water main breaks occur in these infirm areas, they can be quickly isolated. On the other hand, should major fire flows be required in these

areas, closed gate valves can be quickly opened, increasing the water supply significantly.

Portable Water Supply System (PWSS): While the AWSS provides high assurance of

firefighting water supply in the northeast quadrant of San Francisco, major fires can and

do occur at large distances from the AWSS pipe network. In recognition of this, and to provide greater flexibility in deployment and to further extend the "reach" of the AWSS,

the San Francisco Fire Department has developed in recent years the Portable Water

Supply System (PWSS). The basic components of the PWSS are:

- Hose Tenders, trucks capable of carrying 5,000 ft. of large diameter (5

inch) hose, and a high pressure monitor for a master stream,

- Hose Ramps, which allow vehicles to cross the hose when it is charged,

- Gated Inlet Wye, allowing water supply into large diameter from standard

fire hose,

- Gleeson valve, a pressure reducing valve,

- Portable Hydrants, that allow water to be distributed from large diameter

hose

The large diameter (five inch) hose is carried on the hose tenders, together with portable

hydrants, pressure reducing Gleeson valves and other fittings. Each hose tender carries

almost one mile of hose, and is capable of laying this in about twenty minutes. Hose

lengths are intermittently fitted with the portable hydrants, permitting water supply at many locations along the hose, which can be gridded and in effect provides an above

ground water main, (Figure 3). At the time of the Loma Prieta earthquake, SFFD had

four PWSS hose tenders, and has since requested acquisition of an additional eleven.

PERFORMANCE OF WATER SUPPLY SYSTEMS

The locations of pipeline repairs after the 1989 Loma Prieta earthquake are shown in

Figure 4. Zones of potential soil liquefaction, based on maps by Youd and Hoose (1975)

and Hovland and Darragh (1981) are also shown. The most serious damage in the AWSS

was the break of a 12" diameter cast iron main on 7th St. between Mission and Howard

Sts. This location is on the boundary of Infirm Area No. 3 and, moreover, the AWSS pipe

at this location crosses over a sewer line. Soil settlements in this area are thought to have

266
occurred prior to and also as a result of the earthquake, causing the AWSS pipe to bear on

the sewer line, and break. Water flow through this break, supplemented by losses at broken hydrants, emptied the Jones St. Tank. Loss of this supply led to loss of water and

pressure throughout the lower zone of the AWSS. This resulted in critical condition in the

Marina, where damage in the MWSS had cut off alternative sources of pipeline water.

Other breaks in the AWSS system included: (a) a break in an 8 inch hydrant branch, on

Sixth between Folsom and Howard Streets (where the hydrant branch crossed up and over

a sewer line) and (b) five 8 inch elbow breaks, four within Infirm Area No. 3 including one on Bluxome Street where a portion of a building collapsed onto an AWSS hydrant.

Hydrants were the most vulnerable parts of the system, with damage being concentrated

at elbows. Typical construction involves an 8 inch diameter cast iron elbow affixed to a concrete thrust pad beneath the street surface hydrant. Damage at hydrant elbows

occurred as 45 fractures centered on the elbows.

MARINA FIRE AND PWSS

The Marina fire was the largest earthquake-related fire in the loma Prieta earthquake.

Ignition occurred in a four-story wood-frame apartment building at northwest corner of

Divisadero and Beach Sts. Major leakage resulted from the AWSS breaks such that Jones

Street tank completely drained. Leakage continued so that first arriving engines at the

Marina fire, found only residual water when they connected to AWSS hydrants. Due to uncertainty as to the number and location of AWSS breaks, valves connecting the Upper

Zone to the Lower Zone were not opened, and Pump Stations 1 and 2, although available, were not placed in-service immediately but only at 8 PM, following identification and

isolation of broken mains. As a result, pressure in the AWSS Lower Zone was lost for

several hours following the earthquake. The pump stations were operated at half capacity

so as to fill the AWSS mains slowly, out of concern for entrapped air which was

exhausted out of the Lower Zone through Jones Street tank (air could be heard exhausting

through the tank) This operation continued until 10 PM when full pressure was restored

and Jones Street tank had been filled with salt water.

Water to fight the fire was drafted and relayed from the lagoon in front of the Palace of

Fine Arts, approximately three blocks away. The fireboat, "Phoenix" and special hose

tenders were dispatched to the site. Approximately one and a half hours after the main

267
shock, water was being pumped from the fireboat and conveyed by means of 5 inch

diameter hosing, which had been brought to the site by the PWSS hose tenders. Eventually,

the supply of water to the fire was about 6,000 gpm at 180 psi, which continued for over

18 hours. The fire was brought under control within about three hours after the

earthquake.

ANALYSIS OF AWSS

An extended computer simulation of the AWSS network was performed with the program

GISALLE (Graphical Interactive Serviceability Analysis of LifeLine for Engineering).

This program was developed to represent the AWSS as part of a special demonstration

project to develop advanced techniques of computer graphics for lifeline systems and to prove the feasibility of applying these techniques to a real system (Khater, et al., 1989;

Grigoriu, et al., 1989). GISALLE has been checked successfully against special fire flow

tests run by the San Francisco Fire Department. GISALLE is developed to (i) perform

seismic hazard analysis (ii) generate damage states for lifelines consistent with the seismic

intensity at the site; (iii) perform connectivity analysis; and (iv) perform hydraulic

analysis for simulated damage states of the system.

Figure 5 shows a plan view of the system that was simulated to reproduce the conditions on the night of the earthquake. Water in the lower zone was supplied by the Jones St. Tank. The lower and upper zones were isolated from one another with closed gate valves.

Pump Stations 1 and 2 were not included in the simulation to replicate the system

conditions immediately following the earthquake.

Damage of the AWSS considered in the simulation was a broken 12" diameter main on 7th

St., four broken hydrants, and two leaking joints. The approximate locations of these

damaged components are illustrated in the figure.

Figure 6 pictures the water height in Jones Street Tank during the extended computer

simulation (drop in water level in Jones Street Tank was considered in the analysis).

Leaking joints were modeled as open hydrants during the simulation. This figure shows

that the time required to empty the Jones St. Tank was about 32 minutes.

This estimated time to loss of tank agrees with observations during the earthquake.

Scawthorn and Blackburn (1990) report that, when the first engine arrived at the Marina

fire approximately 45 minutes after the earthquake, it could not draw water from the

268
AWSS hydrants. This time for engine arrival exceeds that analyzed for loss of the Jones

St. Tank. Moreover, it was estimated that loss of water from a height of 35 to 18 ft in the

Jones St. Tank took approximately 15 minutes which is consistent with the analytical

results.

CONCLUSIONS

The AWSS performance and computer simulations emphasize how rapidly water can be

lost and how important automatic control of isolation gate valves can be. The simulations

also underscore the importance of hydrant breaks.

The AWSS, would have survived the earthquake and provided adequate water supply for

extinguishment of the Marina fire except that the North-South division of the AWSS, part

of the original concept and design, was eliminated in 1964, resulting in South of Market

Street breaks draining the section of the AWSS North of Market, including the Marina

district.

Although the AWSS pipe network failed in the short term due to a small number of

breaks, this system failure could have likely been precluded if the breaks could have been

identified sooner, leading to placing the pump stations on-line more rapidly. The need for

a rapid damage assessment/reconnaissance technology is emphasized.

The fireboat/PWSS back-up system fulfilled its mission, and the fire was suppressed. This was due in large part to the extremely fortuitous circumstance of the unusual lack of

wind. Normal prevailing wind conditions would almost assuredly have resulted in loss of

several city blocks, with losses in the hundreds of millions of dollars

ACKNOWLEDGMENTS

The support of the National Center for Earthquake Engineering Research, SUNY-Buffalo,

is greatly acknowledged.

269
REFERENCES

Grigoriu, M.D., T.D. O'Rourke, and M. M. Khater, "Serviceability of the San Francisco

Auxiliary Water Supply System," Proceedings. International Conference on Structural

Safety and Reliability, San Francisco, CA, Aug. 1989.

Hovland, H.J. and R.D. Darragh, "Earthquake-Induced Ground Movements in the Mission

Bay Area of San Francisco in 1906," Proceedings. 2nd Specialty Conference of the

Technical Council on Lifeline Earthquake Engineering, Oakland, CA, Aug. 1981, pp.

293-309.

Kafka, A.L., E.A. Schlesinger-Miller, and N.L. Barstow, "The Earthquake Activity in the

Greater New York City Area: Magnitudes, Seismicity, and Geologic Structures," Bulletin

of the Seismological Society of America. Vol. 75, No. 5, Oct. 1985, pp. 1285-1300.

Khater, M.M., M.D. Grigoriu, and T.D. O'Rourke, "Serviceability Measures and Sensitivity

Factors for Estimating Seismic Performance of Water Supply Systems," Proceedings. 9th

World Conference on Earthquake Engineering," Tokyo, Japan, Vol. VII, 1989, pp. 123-128.

Khater, M.M., and M.D. Grigoriu "Graphical Demonstration of Serviceability analysis,"

Proceedings. International Conference on Structural Safety and Reliability, San Francisco,

CA, Aug. 1989, pp. 525-532.

O'Rourke, T.D., M.D. Grigoriu, and M.M. Khater, "Seismic Response of Buried Pipes,"

Pressure Vessel and Piping Technology - A Decade of Progress. C. Sundararajan, Ed.,

ASME, New York, NY, 1985, pp. 281-323.

O'Rourke, T.D., H.E. Stewart, F.T. Blackburn, and T.S. Dickerman, "Geotechnical and

Lifeline Aspects of the October 17, 1989 Loma Prieta Earthquake in San Francisco,"

Technical Report NCEER-90-001. National Center for Earthquake Engineering Research,

Buffalo, NY, Jan. 1990.

Sanborn Ferris Map Company, "Insurance Maps, San Francisco, California," Vol. 4, New

York, NY, 1899.

Scawthorn, C. and T.D. O'Rourke, "Effects of Ground Failure on Water Supply and Fire

Following Earthquake: the 1906 San Francisco Earthquake," Technical Report

NCEER-89-0032. National Center for Earthquake Engineering Research, Buffalo, NY,

Dec. 1989, pp. 16-35.

Scawthorn, C. and F.T. Blackburn, "Performance of the San Francisco Auxiliary and

Portable Water Supply Systems in the 17 October, 1989 Loma Prieta Earthquake,"

Proceedings. 4th U.S. Conference on Earthquake Engineering, Palm Springs, CA, Vol. 1, 1990, pp. 171-180.

270
REFERENCES (Cont.)

Trautrnann, C.H., T.D. O'Rourke, M.D. Grigoriu, and M.M. Khater, "Systems Model for

Water Supply Following Earthquakes," Lifeline Seismic Risk Analysis - Case Studies. R.

Eguchi, Ed., ASCE, New York, NY, 1986, pp. 30-50.

U.S. Coast Survey, Topographic Map of "City of San Francisco and Its Vicinity,

California," surveyed by A.F. Rodgers, 1857.

Youd, T.L. and S.N. Hoose, "Historic Ground Failures in Northern California Triggered by

Earthquakes," Geologic Survey Professional Paper 993. U.S. Government Printing Office,

Washington, D.C., 1978.

271
Jones Street Tank

Fire Boat

Manifold

(Bertti for Fire Boat)

Lower Zone

Upper Zone

Contour Line

Contour Interval: 30m = IOOft

0 miie

.6 km

Figure 1: San Francisco AWSS

Twin Peaks

Twin Peaks Reservoir

(lOMiinon Gallons)

Ashbury Tank

Jones SL Tank

Pump Stations

SFFD Auxlli^r^W^ Systerr

Figure 2: Schematic Cross-section San Francisco Auxiliary Water Supply System

272
Figure 3: San Francisco Portable Water Supply System (schematic)

273
Zone of N 0 . 3000 ft Concentrated i 0 soom

Legend

• Repair MWSS Main Repair AWSS Main

X Repair MWSS Service Repair AWSS Hydrant or Leal<ing Joint

Figure 4: Water Supply Pipeline Breaks and Zones of Soil

Liquefaction Caused by Loma Prieta Earthquake (after

O'Rourke, et al., 1990)

274
Figure 5: Conditions Used in Computer Simulation of AWSS

Performance During the Loma Prieta Earthqualce

Time (Minutes)

Figure 6: Results of AWSS Extended Simulation

275

SEISMIC RELIABILITY ANALYSES OF LARGE SCALE LIFELINE

NETWORKS TAKING INTO ACCOUNT THE FAILURE PROBABILITY

OF THE COMPONENTS

Tadanobii SATO and Kenzo TOKI

Associate Professor and Professor

Disaster Prevention Research Institute, Kyoto University

ABSTRACT

To assess the seismic reliability of large scale lifeline networks and taking into account

failure probability of the components, we developed an algorithm which has only polynomial

complexity to enumerate paths in the network. Using this algorithm we have developed a new approximate calculation scheme, call the point Tiiatching method. The uncertainty of

the attenuation law, shear wave velocity of ground and component's failure level are considered to calculate the seismic reliability of the network. This program can be run on a 32

bit desktop computer with the main memory of 16 MB and the operation time of 5.3 MIPS.

This program package offers you an interactive capability, to select supply and demand

nodes a,s well as show them on screen. A check of applicability of our new method is made

by hypothetical seismic reliability analysis of a gas supply network composed of 1765 nodes

and 1764 links.

INTRODUCTION

Because damage to a single location in a utility network often affects a major portion

of the entire system, the reliability of lifeline networks during earthquake is a major concern

for the prevention of urban hazards. When we are to assess the seismic reliability of lifeline

systems, the following items must be considered: seismic activity and the attenuation of

seismic waves; microzonation that takos into account to the local geological nature of each

area; structural response and system analyses with proper modeling of components; and

lifeline serviceability requirements. Seismic reliability analysis should include an efficient

method for computing the reliability of the lifeline as a network interconnected nods and

links. Because enumeration of network states in a seismic environment usually has exponential complexity, seismic reliability analyses of large scale networks have not l:)een feasible as the number of components increases. To overcome this deficiency we proposed an efhcient

procedure for assessing the seismic reliability of lifeline networks (Ref.l). For a fixed earthquake on an active fault zone, we proved that the network took at most 2n^ — 2n-\-2 states, n being the number of components. In the algorithm, we used the concept of the critical

distance to the earthquake fault (Ref.2). A network is assumed to consist of liuks and nodes,

and a node and link to fail if the seismic response exceeds a particular level at any point

in each component. The intensity of the seismic response, Y, at a particular point in the

277
network components is given through an attenuation law in terms of tlie earthquake magnitude, AI, the shortest distance to the rupture zone,r, and the parameters Ci, {k = 1,2 - ••) which express the source mechanisms and the effect of local geological parameters around

the point. If the network component can sustain the magnitude of response expressed by

Y*, the shortest safe distance (the critical distance) between the component and the fault

rupture is inversely solved from the attenuation law

r* = /(M,C,,y*) (1)

The sphere of the radius with this distance centered at the element point defines the

transition boundary for the component because it divides three dimensional space into the

component of working and non-working states. The shape of the transition boundary for a node is a sphere. For a link it is a combination of a row of spheres and idealized by a

circular cone with spheres at both end provided that there is linearity of the failure distances

along the link. An example critical distance r* obtained from an attenuation curve of strain

(full line) and an allowable strain of l)uricd pipe at a certain point s* is shown in Fig.l.

Because the uncertainties of attenuation law and allowable strain of the component are not

considered, the failure probability of the component changes from 0.0 to 1.0 if the shortest

distance to an earthquake fault r becomes less than r* as shown in Fig. 2.

The purpose of this paper is to relax this binary condition of component's failure

probability. The seismic reliability of a network may decrease if we take into account uncertainties of several factors. Especially the effect of uncertainty of attenuation law must

be examined carefully.

DEFINITION OF FAILURE PROBABILITY OF COMPONENT

Network components are assumed to fail when the strain induced in the pipe exceeds a threshold level or the ground is liquefied. The Japanese specification for the earthquakeresistant design of gas pipes (RcL3) defines the formula with which to calculate pipe strain

as

e = /3-S, 6 = {l-a)-U (2)

in which /? is the coefficient for transferring relative displacement between the pipe and

ground into the pipe strain, a the transmission coefficient, U the ground displacement given

by

U = -,-T-SvK-cos{^) ' (3)

TT"^ 111

in which T is the natural period of the ground, Sy the response velocity value per unit

seismic coefficient, A' the design seismic coefficient and z the depth of the pipe.

By substituting Eq.(3) into Eq.(2) the strain induced in a pipe is expressed as follows:

e = /3.{l-a).^.T-SvK-cos^ (4)

Because the values of T, Sy and A' scatter around their mean values of T, Sy and A', Eq.(4) can be rewritten

, = ^.a-„)4.T.5^.r.cos^.J.|.f (5)

278
Fig.l Relation between the seisinic pipe strain and critical distance from an cartliqiiake fault

-I

I

1

^ o O

6

as

°'1Q-''

I ,

I I I I I !l r

I i t I I ! 1 1

Distance r(Km

I i I 1 i 111 , 'icf

Fig. 2 Relation between failure probalulity of a component

and critical distance from an earthquake fault (Not considering uncertainty)

279
Taking logarithm of Eq.(5) the expression of pipe strain is divided into two parts.

loge = \og{(3 • (1 - a) • — • T • 5V • K cos —-} + log = + log =^ + log = (6)

TT-' 211 I by A

The first term of right-hand side Eq.(G) is derived from mean valnes of parameters. The

remaining second, third and fourth terms are assumed to be random variables with normal

probability distributions N{pT,o\), N{j.i Sy,<y~Sv) "^"^ ^{1'k-,^^k)) respectively. If we define

£q as follows:

2 _ TTZ e, = ^.{l-a*)---T-SyK-cos-- (7)

TT" 111

logs has a normal probability distribution with a mean value of //j^log^o a variance of

cr^=(7y-f cr|^4-o"|^'. To calculate Eq the value of K must be expressed hy an attenuation law

in terms of the earthquake magnitude, m, and the shortest distance to the rupture zone, r. Because the attenuation laAvs proposed so far are functions of the magnitude and epiccntral

distance, we have used the following relation for A' (Rof. 1) K-g = 221- 10°-3°«"^(r +

30)-i

(8)

in which g is the acceleration of gravity.

The failure probability of a component for an earthquake with magnitude m at critical

distance ri is calculated as shown in Fig. 3. If the allowal)le strain level e* is a definite value

the component loses its function on the condition of e > e* . The failure probal)ility Pf{m, rj),

therfore, can be calculated by the area of shaded part in Fig. 3 or by the following formula,

Pf{m,f,) = P{e>e*) (9)

An example relation between failure probaljility of a component and the critical distance

from an earthquake fault is given in Fig. 4. The distance at where the failure probability

being 0.5 is obtained from the condition of = ^*

If the allowable strain s* is a random variable obeying a logarithmic normal distribution

with the mean value of //;-=log£:*, and the variance of rr^., then failure prol)a1)ility of the

component p/(m, f) is given by

pj{m,r) = 1.0 -^ ^'r'~^'' ) (10)

in which ^{x) is the standard normal distribution function.

SEISMIC ENVIRONMENT

The gross parameters of the seismic source, which are required to reliability analysis

of lifeline network, are the fault length and width, the seismic moment and the magnitude

of the earthquake. The seismic moment, A/q, is the fundamental parameter used to measure

the magnitude of an earthquake caused by a fault slip, but the surface magnitude, m^, is

280
10'

I ,I I I I 1 1

[ jlj 1 M I —I 11 I I llj ^—TTTTTTTj

Distance 7'(Km)

7

J I M I I III , cr 'icf

Fig.3 Calculation of failure probability of a component at several

critical distances from an earthquake fault

o

Distance 7' (Km)

Fig. 4 Relation between failure probability of a component

and critical distance from an earthquake fault

(Taking into account uncertainty)

281
used in engineering. We have the relation between and given by GoUer (Rcf.5). The

fault area, S, also is related to Mo]

S= 1.88- IQ-^Wl;'^ (11)

The network component will fail with probability, Pfim, r), if the transition boundary

with the critical distance ?~ intersects the earthquake rupture area. Taking into account the

probabilistic nature of an earthquake occurring, we have defined an active fault zone. The

collocation of earthquake rupture on this active fault zone is determined from a probabilistic concept. We assume rectangular areas (the length of fault to be twice of the width) for

the active fault zone and for a rupture caused by an earthquake as shown in Fig. 5. The

collocation of both rectangles is arranged with the axes of symmetry parallel. We define the

transition area with failure probabiUty o{ pf{m,r) as the intersection between the critical

boundary of a component of the network and the active fault zone as shown in Fig. 5. For a node it is a circle; for a link it is the cross section between the active fault plane and a

circular cone with a sphere at both end.

To formulate network reliability, we must assume that this transition area with failure

probability pf may intersect an earthquake rupture with magnitude m; therefore, it is convenient to look at the positions of rupture from the center of the earthquake. We defined a coordinate transformation (Rcf.l) by which the position of earthquake rupture can be represented by the center of the rupture. An example of the collocation of this nr-wly defined

transition area for a simple network composed of twelve nodes and eleven links is shown in

Fig. 6. We assume that only critical boundaries of nodes D and E compose transition areas. The relation between the failure probability and critical distance was a continuous function

as shoAvn in Fig.4. For purpose of numerical simplicity we discretize this relation as shown

in Fig.G. There are four transition areas for each node with different failure probability and

these areas divide the active fault zone into 12 regions (defined as influence regions) that

are mutually exclusive and collectively exhaustive regions. The network condition changes

from one region to the other. For example the region 8 expresses the network condition that

nodes of D and E fail simultaneously with probabilities of 0.5 and 0.25, respectively.

NETWORK RELIABILITY COMPUTATION

In order to illustrate the reliability computation a multi-terminal relial)ility measure

is used that is defined as the probability that the given source nodes can be connected to all specified terminal nodes in the network. Let I^{x,y/w) be an relial)ility index of influence

region i defined by the probability to satisfy the function of a network after a magnitude m

earthquake with a rupture centered at (x, y). How to calculate the reliability index of region

8 in Fig.4 (/g) is explained in Table 1. The connectivity from nodes A and B to nodes K

andL is chosen as the reliability measure. There are four cases based on component's failure

condition. I^{x,y /m) becomes 0.75 by adding all probabilities of network functioning.

For simplicit)^ we consider only one active fault zone in the following analysis. The transition areas divide the active fault zone into some M influence regions .4, {i = 1, 2, • •

• , M).

Each A, region corresponds to some state of the network and I,{x,y/'in) is constant within

At, so that the reliability of the network, G, conditioned on magnitude m is M M

RiG/m) = j:WAt/m)-A,}/j:A, (12)

t=i t=i

282
Transition boundary

with failure probability p

Earthquake rapture

Fig. 5 Collocation of transition bonndary, an earthquake raptnre in the active fault zone and transition area of a component

283
Evaluation point Active fault zone

Fig. 6 Example of the collocation of tran.sition area with different failure probability for simple network

(Only the transition areas of nodes D and E are considered)

284
Table 1 Calculation of reliability index

Node D Node E Reliabilty measure Probability

1 F F NS

2 F NF NS

3 NF F S (1 - 0.25) X 0.5 = 0.375

4 NF NF s (1 - 0.25) X (1 - 0.5) = 0.375

Reliability index /g = 0.750

F: Failure S: Satisfy

NF: Non failure NS: Not satisfy

Table 2 Calculation of reliability for the connectivity

from nodes A and B to nodes K and L

Region No. Reliablity index /j Number of evaluation points TV,

1 1.0 177 177

2 0.75 44 33

3 0.5 12 6

4 0.25 6 1.5

5 0.0 1 0

6 0.5 2 1 7 0.75 11 8.25

8 0.75 2 1.5

9 1.0 31 31

10 1.0 8 8

11 1.0 4 4

12 1.0 2 2

Total 300 273.25

Reliability R = {J^ Ir N.)/ J2 =

j=i t=i

: 0.9108

285
in which we assume uniform distribution of earthquake occurrence on the active fault zone.

Point matching method : The most time consuming part of the developed program is the

calculation of area of influence region After detail check of program statements we found

that the order of enumeration for a network with n elements was 0{n^) due to the existence

of nested DO ROOPS to calculate ^, although our algorithm guarantees the order of O(n^)

(Ref.l). To overcome this deficiency we have developed an algorithm named "point matching

method". The idea of the method is simple. Evaluation points are uniformly distributed on

the active fault zone and the area of region A, is assumed to be proportional to the number

of evaluation points included in the region yi,. The value of reliability index defined by

/,(x,y/m) is assigned to each evaluation point. If the number of evaluation points in the

region A^ is then Eq.(12) is rewritten as follows:

R{G/m) = j:WNjni) • A^}/^iV. (1.3)

t=i t=i

The reliability for the network shown in Fig.6 is calculated in Table 2 using the above

mentioned procedure. The number of evaluation points is 300 and the included evaluation

points in each influence region is also given in Table 2.

Application of minimal cutset: In Table 1 we counted out all possible case for calculating

reliability index. But this is not feasible as the number of collectively exhaustive regions

increases. For an illustrative purpose a network shown in Fig. 7 is considered. The reliability

measure is connectivity from nodes Si, ^2 and to nodes D2 and Da. The transition areas

of nodes A, B, C and D are intersected with active fault zone and only single failure probability for each transition area is assigned as given in Table 3. If we calculate the reliability

index of shaded influence region by taking into account all possible cases we have to count

out 16 (2^) cases because this region is included inside of four transition areas composed

of nodes A^ B, C and D. The computation time to calculate the reliability index expands

exponentially as the number of related transition areas of an influence region increases. To

avoid this difficulty we use minimal cutset which is the subset of network components. If only one component in this subset survives the connectivity of the network is satisfied. In

the example given in Table 4 the minimal cutset is the combination of nodes C and D

because both nodes must survive to satisfy the reliability measure. The reliability index

of this influence region, therefore, can be calculated by counting out all cases satisfying

reliai)ility measure for nodes A and B and multiplying survival probability of nodes C and

D as shown in Table 5.

A MODEL OF GAS NETWORK AND AN ACTIVE FAULT ZONE

We considered a gas supply network (Fig. 8) composed of 1765 nodes and 1764 links.

The network shown in Fig. 8 is an idealization of the southern portion of the middle pres- sure A line (gas pressure: 10>p>3kg/cm^) and B line (3>p>lkg/cm^). Six source nodes

expressed by astrisks are connected to the high pressure line through regulator stations, and

640 terminal nodes are connected to source nodes of the low pressure line (p <lkg/cm^)

through district regulators. Based on the gas demand 116 terminal nodes are chosen as the

demand nodes. To evaluate the reliability of this network we have chosen a i^imple connectivity measure, the probal)ility that gas can reach all the demand nodes.

286
Fig. 7 A network to apply the iiiiniinal cut.'iGt

Table 3 Failure probability and survival probability

Node P} Pi Nofle A 0.3 0.7

Node B 0.4 0.6

Node C 0.9 0.1 Node D 0.8 0.2

Tabln 4 Calcnlating reliability index without using, niinimal cutset

Nr.do A Node B Xodn C Node D I'elinliility measure Proliahility

1 0 0 0 0 0 0.7x0.6x0.1x0.2=0.0084

2 0 0 0 X X

3 0 0 X 0 X

4 0 0 X X X

•5 0 X 0 o 0 0.7x0.4x0.1x0.2=0.0056

6 0 X 0 X X

7 0 X X 0 X

8 0 X X X X

9 X 0 0 0 0 0.3x0.6x0.1x0,2=0.0036

10 X 0 0 X X

11 X 0 X 0 X

12 X 0 X X X

13 X X 0 0 X

14 X X 0 X X

15 X X X 0 X

IG X X X X X

Reliability index 0.017G

287
Table 5 Calculation of reliability index using minimal cutset

Node A Node B Reliability nieasiiic Probability

1 0 o o 0.7x0.6=0.42

2 o X o 0.7x0.4=0.28

3 X o 0 0.3x0.6=0.18

4 X X X

0.88

Rclial)ility index 0.1x0.2x0.88=0.0176

Middle pressure gas supply network model in Shounan

(G siiplly iiodees and 116 demande nodes)

288
An active fault zone is considered (Fig.9). Tliis zone includes the fault area of the 1923

Kwanto Earthquake. The shear wave velocity and thickness of the ground at each node are determined by using the geological data base constructed from the results of standard penetration tests conducted at 1618 points in the area concerned. The depth of the buried pipe

elements is cissumed to be 1.2m.

COMPARISON OF CPU TIME FOR EXECUTING THE PROGRAM

The main system of the data processing center of Kyoto University consists of a largescale general-purpose computer, FACOM M-780/30 and two super computers, \T-400E and

VP-200. We use M-780/.30 and VP400E systems for comparing CPU time to analyze seismic

rehability of a sample network. A FORTRAN program developed by using M-780/30 can be executed by a vectorized computer (VP-400E) without any modification. Decrease of

execution time is based on the rate of vectorization of each program unit. To decrease effi- ciently execution time of the program unit there is a software with an interactive capal)ility,

to show the execution time of each program unit on VP- lOOE and on M-78n/30; the number of execution times of each program unit; a possibility for vectorization and procedures

to increase computation speed of each program unit. A comparison of needed CPU time

between a vectorized computer (VP-400E) and a general purpose computer (M-780/30) for

analyzing seismic reliability of a gas supply network with the 3529 elements gives a result

that the vectorized program attains 5.5 times computation speed at the earthquake magnitude 6.6, 17.4 times at the magnitude of 6.8 and 34 times at the magnitude of 7.0. As the

earthquake magnitude becomes large the efficiency of vectorized program increases because

the vectorized length (the number of data processed by vectorizer) becomes long.

To check the accuracy of the point matching method the seismic reliability of above

mentioned gas supply network is calculated for earthquake magnitude of 6.6, 6.8 and 7.0. The number of evaluation points is 5000. The results also show in good agreement between the seismic reliability calculated by the exact method and that by the point matching

method. Although the program of this method is executed on M-780/30, the CPU time is attained almost 6 times lesser than that for exact solution obtained by using super computer

(VP-400E).

APPLICATION

A work station, NEWS- 1860, with 5.3 MIPS processing speed is mainly used for calculating seismic reliability of the gas network shown in Fig.8. In the network there are 640 terminal nodes. We classified these terminal nodes into five levels based on their gas

demands. The case of 116 demand nodes is the fourth level. The standard deviations of

random valuables appeared in Eqs.(6) and (10) are determined by using the observed and

experimental data as follows:

aT = 0.151, (75^ = 0.105, cr/^ = 0.244, a,. = 0.04

The relation between the failure probability of a component and critical distance is discretized every IThe calculated seismic reliability against a random earthquake for the fourth

level is shown in Fig. 10. Three cases are presented in the figure. First is the case of without

289

•/^ryT>-ffi^rmifl.YtiTlitlT" 1 1 1

1 0.00 0.20 O.'O 0.60 0.80 1.00

Reliability

Fig. 12 Probability densiiv

of seismic rolialjilitv

0.00 0.20 Relability

Fig. 13 Cumulative distribution of

seismic reliability

291
an}^ uncertainties, so that only the binai)^ faihire probal>ility for each component is assumed.

Second is that of taking into account only the uncertainty of attenuation law, and third includes all uncertainties. Because the uncertainty of attenuation law is largest the seismic

reliability of network decreases drastically when the uncertainty of attenuation law takes

into account.

The distribution of reliability index on the active fault zone is calculated for each

earthquake magnitude as shown in Fig. 11. This is Ihc result for earthquake magnitude

7.0. The probability density function of seismic reliability of the network is obtained from

Fig. 11 as shown in Fig. 12 based on Eq.l3. By integrating the probability density function

we can draw the cumulative distribution function of seismic reliability of network as shown

in Fig. 13. Form this figure we can estimate the probability guaranteeing a certain level of

seismic reliability of network.

Uncertainties of several factors for assessing seismic reliability of large scale lifeline system have been implemented in the algorithm with which to analyze the seismic reliability.

It uses a new approximate calculation scheme called point matching method and minimal

cutset theory. Calculation of the seismic reliability of an example network shows that newly

developed program package can be used with large networks. The result reveals that the

eflFect of uncertainty of attenuation law is the largest on the seismic reliability analyses of

networks.

(1) Sato, T., "Seismic reliability analysis of lifeline networks taking into account fault extent

and local ground conditions", Natural Disaster Science, Vol.6, No. 2, 51-72, (1981).

(2) Moghtaderizadeh, M., Wood, R.K., Der-Kiureghian, A., Barlow, R.E. and Sato, T.,

"Seismic reliability of flow and communication networks". Lifeline Earthquake Engineering,

The Current State of Knowledge, ASCE, 81-96 (1981).

(3) Japan Gas Association, "Specification for earthquake resistant design of gas pipelines",

March (1982) (in Japanese).

(4) Kawashima, K., Aizawa, K. and Takashina, K., "Attenuation of peak ground acceleration, velocity and displacement based on multiple regression analysis of Japanese strong motion records". Earthquake Engineering and Structural Dynamics, Vol.14, pp. 199-215 (1986).

(5) Geller, R. J., "Scaling relation for earthquake source parameters and magnitude", Bull.

Sei.sm. Soc. America, Vol.66, No.5, pp. 1501-1523 (1976).

CONCLUSION

REFERENCES

292
EARTHQUAKE DAMAGE ANALYSIS ON

TELECOMMUNICATION CONDUITS

Koji Yagi" , Shinji Mataki^' and IMobuhisa Suzuki ^'

1) : Project Group Manager

Field Systems Research and Development Center

Nippon Telegraph and Telephone Corporation (l\nT)

2) : Field Systems Research and Development Center

Nippon Telegraph and Telephone Corporation (I\nT)

3) : Senior Research Engineer

NKK Corporation

ABSTRACT

A telecommunication conduit was severely damaged at a threaded joint during the 1983

Nihonkai Chubu earthquake, which hit the northern part of Japan, as well as other

underground structures. The damaged telecommunication conduit was a 75 mm diameter steel

pipe connected with threaded joints.

In order to clarify the cause of the damage, the relationships between the strength of the

threaded joint and permanent ground displacement are investigated in this study, which

displacements were occurred along the conduit due to liquefaction of sandy soil.

Experiments on the threaded joint were conducted to investigate the deformation

characteristics against compressive force, tensile force and bending moment. Critical

axial strain of the conduit subject to compressive force was 0.085%, for example.

Compression tests of the buried conduits were conducted in a soil container with different

soil conditions. Deformation of the joints were very similar to the damaged joint

observed at the site after the earthquake in the both soil conditions. The load versus

displacement curves, however, were not so different each other.

The permanent ground displacements along the conduit were measured by comparing the aerial

photographs before and after the earthquake. As a result of the investigation of the

ground movement, compressive ground strain along the conduit reached to 0.35%, which was

large enough to cause the damage of the joint of the conduit.

It is concluded that the axial rigidity and deformabi I i ty of the joint of the conduit is a critical parameter for the seismic design especially in the liquefiable area, where the

permanent ground displacement are expected.

293
I NTRODUCT I ON

Structural safety and maintenance of communicational function of lifeline communication

systems at the time of an earthquake are important subjects for disaster prevention, hence

investigations have been made from various viewpoints . ^' Investigation of the

earthquake resisting strength of conduits for buried communication cables is one of those

subjects. This report describes the results of analysis of damage to conduits for

communication cable in Nohiro City. The damage was caused by Nihonkai-chubu earthquake

in 1983. The analysis concern the relationship between the strength of the conduit joint

and the permanent displacement ^' of the ground.

DAMAGE TO CONDUITS FOR COMMUNICATION CABLES

An example of damage to a conduit joint is shown in Photo. 1. This conduit is a steel

pipe with 89. 1 mm outer diameter and 4. 2 mm wa 1 1 thickness. It is connected by a threaded

joint of 120 mm total length. As shown in the photograph, jointing parts of the conduits

show crank like bending by rotation around the socket. However, because the rigidity of

the socket was higher than the conduit, deformation of the socket was hardly found, and

one of the conduits was bent until the section of pipe was completely closed, while the

section of another conduits remained open because of the plastic deformation of the thread

ridge in spite of the bending.

DISTRIBUTION OF GROUND PERMANENT DISPLACEMENT

Fig. 1 shows the plan of one section (length: about 250 m) of Telecommunication conduits

which includes damaged positions (A). Also, permanent displacement vectors, which were obtained by an aerial photographic survey, are shown. Each measuring point was set on

both sides of the conduits at intervals of about 20 m and permanent displacements of the

conduits were obtained by interpolating measured data from pairs of measuring points which

hold conduits between them. Fig. 2 shows the results.

As seen in Fig. 2, the distance between the manholes at each end shows a relative

reduction of about 85 cm, distribution of permanent displacement in the direction of the

pipe axis shows nearly linear change over the total length of about 250 m, and compressive

strain of about 0.35% was generated. In addition, the horizontal distribution of

displacement in the direction which is rectangular to the pipe axis is small within an

interval of about 50 m around the damaged position, and shows 34 cm maximum displacement

at the front and rear ends of the above interval. Displacements in the vertical direction

294
(amount of subsidence) varies in the range of 26 to 47 cm but, as a whole, subsidence is nearly uniform.

Permanent displacement in the direction of the pipe axis and permanent displacement in the

direction rectangular to the axis, which were described above, are called lateral shifts

and can be shown by the models in Fig. 3. Permanent displacements which were observed in Noshiro City were expressed by a model as seen in Fig. 3. The upper limit of the

relationship between the length of transition interval and relative displacement 5 , and

the relationship between the width of the permanent displacement W and permanent

displacement 5 is shown by Table 1. Accordingly, in the case of displacement in axial

the direction of the pipe, axial strain of the ground (e, 5/1) is Eg = 3% (constant

) when L ^ 50 m, but axial strain of the ground in the case of 50 m < L issg =0.6%

which is inversely proportinal to L. For instance, when L - 250 m, which is the damaged

interval, is substituted in the above equation, Cg = 0.6%, which is about 1.7 times the

value of the actual measurement (about 0.35%), is obtained. For the direction rectangular

to the pipe axis, W = 100 m, 5 = 0.2 m is obtained in the neighborhood of damaged

position. Accordingly, 8 = 1 m is obtained when W = 100 m is substituted in the above

equation. The upper limit of displacement by actual measurement is about 5 times the

damaged position.

EXPERIMENT COMPRESSIVE STRENGTH OF THE

CONDUIT JOINT

Fig. 4 shows the Load-Displacement Curve which was obtained from compression tests on a conduit joint of conduits of 220 m in total length. Yielding load was about 20 tonf and

maximum load was 26.7 tonf. Yielding displacement and displacement of maximum loading

point were about 1 mm and about 3 mm, respectively. Axial stress on the conduits which

corresponded to yielding load and maximum load were 1785 kgf/cm^ (0.085%) and 2330 kgf/cm^

(0.111%), respectively. As shown in Photo. 2, for the inside of a joint, the screwed part

of one conduit was pushed in causing it to penetrate and ride over the inside surface of

the other conduit.

SIMULATION EXPERIMENT OF DAMAGE

IN A SOIL TEST TANK

To simulate the damage to a conduit joint, one conduit was buried in a soil test tank made

of steel (LBD = 5x2x2 m) and was deformed by applying an axial force using a hydraulic

jack, as shown in Fig. 5. To investigate the effect of spring properties of the ground.

295
hard condition (Case H/N = 17 to 21) and soft condition (Case S/N = 4 to 5) were used

for test ground. Spring properties of the ground in the direction rectangular to the pipe

axis were directly measured by pulling up a single pipe as shown in Fig. 6.

Fig. 7 shows the Load-Displacement Curve which were obtained from experiments on the

spring properties of the ground. As shown in the figure, there is a large difference

between the spring properties of the ground in Case H and Case S. Namely, in Case H, in the early phase of deformation where displacement is less then 5 mm, the spring factor is so large that k = 29.3 kgf/cm\ and the load shows decrease after the maximum load is reached with a displacement of 20 to 25 mm. It then decreases to about 70% of the maximum

load in the phase of displacement of 100 mm. On the other hand, the Load-Displacement

Curve in Case S shows a rounded appearance as a whole. Particularly, the spring factor in the early phase of deformation is k = 7. 0 kgf/cm^ and it shows an increase of load

without clear yielding. Maximum load is reached in the phase of displacement of 100 mm, and after that load shows a gradual decrease.

The relation between load and displacement, obtained by simulation experiment, is

shown in Fig. 8. Maximum loads are 23 tonf for Case H and 21 tonf for Case S which

are nearly the same, and proportional factors in the early phase of deformation are 49.8 tonf/cm for Case H and 40.5 tonf/cm. In this case, such a large difference in spring properties as in Fig. 7, is not observed. The joints of specimens which were

dug out show deformations as shown in Photos 3 and 4. These deformations simulate

actual damage very well. In addition, protective conduits which were connected to

sockets, were bent by rotating deformation, and plastic deformation remained.

ANALYS IS OF DAMAGE

For long column buckling of a straight elastic beam which is placed on an elastic support,

and has infinite length, the fundamental differential equation is expressed by (1). The

buckling load N and the buckling wave length L are given by (2) and (3) respectively.

El VT + N

^ + kL Dy = 0 (1) N = 4EliSM2) L = (3)

dx^ dx^ 1.414)3

Where )3 = (ki D/4EI)''^\ Figs. 9 and 10 show the results of calculations for the

buckling load (Eq. (2)) and buckling wave length (Eq. (3)), taking k l which is the spring

factor of the ground in the direction rectangular to the pipe axis, as parameter. L = 0. 98 m, N = 470 tonf for Case H, and L = 1.40 m, N = 240 tonf were obtained. In these

cases, apparent strains generated in the protective conduits are 1.90% and 0.97%,

respectively and both values exceed the elastic limit (0.085%) of strain which is

296
generated in the conduits. Thus, elastic buckling in the long column mode is found not to occur in the ground condition of the soil tank.

Consideration is now given to the case in which the threaded joint shows plastic

deformation under axial force as shown in Photo. 2, and shifts to deformation by rotative

movement of the socket as shown in Photos. 3 and 4. In this case, conduits becomes

elongated because of the loss of axial rigidity of the socket, and rotative movement of

socket results. Hence, the total length of conduits is assumed to become shorter by the

rotative displacement of the socket. The behavior of conduits at the time of an earthquake can be estimated by approximating the half of value of reduction as

displacement of free and of semi-inf ini te straight conduits in uniform field of strain of

ground

When displacement of the ground is distributed in an axial direction of a semi-inf ini te straight conduits, the equation of balance is expressed by (4). Assuming the spring

property of the ground by elasticity to complete plastic body, displacement of pipe end

Upe is expressed by equation (5), and the length of si ippingj? s i i p is expressed by

equation (6) . Results of calculations using equations (5) and (6) with Ucr =0.1 cm

are shown in Figs. 11 and 12.

EA

^ + Tz-DkL [U (X) - Up(X)] =0 (4)

dx^

Upe =7^77-'^^^' + «'Uc.M . (5)

2Q:'Ucr

j^siip=-—|— (eg-aUcr) (6)

where, a = (TrDki /EA)'^^ kt : Spring factor and Ucr: Relative displacement of

y i e I d i ng.

As described formerly, assuming that eg = 0.35% and displacement of the pipe end is 10

cm, k L ^ 5. 5 kgf/cm^ is obtained from Fig. 11. Frictional force of the ground is estimated to be about r =0.55 kgf/cm^ because Ucr = 0.1 cm. This frictional force is significantly larger than the frictional force in a completely liquefied state, so the

strength of the ground in the neighborhood of the conduit is assumed to be little reduced.

The length of slip is estimated to be about 30 cm from Fig. 12.

297
CONCLUS I ON

Earthquake damage to conduits for buried communication cables, which was caused by

Ni honl<a i -chubu earthquake, was analyzed in relation to permanent displacement of the

ground, and simulation experiments were carried out using a soil tank. The results of the

expriments showed that a compression strain of 0.35% was caused in the ground in an axial

direction by permonent displacement. Hence, the collapse of the joint is assumed to be

caused by this compressive strain. Spring properties of the ground at the time of

generation of permanent displacement was estimated from fundamental analysis of

deformation. Frictional force in the neighborhood of the conduit was r =0.55 kgf/cm^

at least, and this value is assumed to be sufficiently larger than the value in the state

of complete liquefaction.

FUTURE DIRECTIONS

We have studied the cause of the conduits damage due to each of ground motion and ground

deformation. Particularly, as concerns ground deformation, the actual damaged conduits by

Nihonkai -chubu earthquake was an object of study, and we have investigated the cause of

the conduits damage due to ground deformation with analytical method. The experiment of

this paper has two purposes. One is simulation of conduit damage by Nihonka i -chubu

earthquake, and the other is verification of propriety of above analysis results.

In the future, we will applicate these results, and investigate how to construct the high

reliability conduit facilities and reinforce of earthquake resistant for existing conduit

faci I ities.

REFERENCES

1) T.Suzuki, K. YAGI and IVLHirofuji : Structural Analysis of Damaged Telecommunication

Conduits, 45THJSCE. Vol.1, 1176-1177,1990

2) K. Yagi, S. Takada, KHattori, S. J. Sheng : A Study of Liquefaction Countermeasures for

Manholes Under the Pavement, 8th Japan Earthquake Engineering Symposium, 2085-2090, 1990

3) ll/l Hamada, S. Yasuda et al. : A Study and measurement of Permanent Ground Displacement

due to Liquefaction, JSCEIII, No. 376, 211-220, 1986

4) l\L Suzuki, A.Hagio : Safety Assessment of Welded Pipelines Undergoing Large Ground

Deformation, Proc. ofPLDiv., ASCE, 108-119, 1990

5) M Suzuki, IVl Hamada : Deformation Property of Earthquake Damage to Buried Conduits and

Conduits Network, Proc. of Structural Engineering, Vol.37A, 1497-1506, 1991

298
Photo. 1 Example of Teleconnunication Conduits damage caused

by Nihonkai-chubu Earthquake

1/ V

1 f \

(Jo) (

f,

-J Bj

q

27.0

i— 251.7 5.5 < >^ ^

Torigoya Route No. 2 MH Torigoya Route No. 1 .MH

Fig. 1 Laying line of Telecommunication Conduits in the interval of damaging.

299
300
0 Displacement in the direction (2) Displacement in the direction

of pipe axis rectangular to pipe axis

Fig. 3 Model of lateral shift of ground

L S

Displacement in the

direction of conduit

L^5 0 3/1 0 0 *L

5 0 <L<4 0 0 1. 5

Displacement in the

direction of rectangular to conduit

1 5 0 1/1 0 0*W

1 5 0 <W< 5 0 0 1/3 0 0 *W+1

(m)

Table 1 Upper limit of distribution of permnent displacement (lateral shift)

301
I 1

' '

' 0 10 20 30 40

Displacement (mm)

Fig. 4 Load to Displacement curve of threaded joint

Photo. 2 Section of joint after compression test

302
Soil tank

2300 120

///f//

2300

' - 77^

Jack

Fig. 5 Simulation experiment of damage Fig. 6 Measuring method of

ground spring property

5

4

cz B 3

-aS 2

easel - - case2

^ " "

"

/

'/

! 1 ! 1

*

1 1 II

0 40 80 120 160

Displacement (mm)

Fig. 7 Vertical and upward ground spring property

30

-a

10

J L 0 30 60 90 120 150

Displacement (mm)

Fig. 8 Load to Displacement Curve obtained by Simulation Experiment

303
Photo. 3 Specimen after test (Case H)

Photo. 4 Specimen after test (Case S)

304
1000 F

1.0 10.0

kr (kg/cm*

)

Fig. 9 Buckling load

3.0

2.0

-1

1.0

1

! ! 1 0 10 20 30 40

kT (kg/era^)

50

Fig. 10 Buckling wave length

305
(%)

Fig. 11 Displacement of semi-infinite straight conduit

0 0.2 0.4 0.6 0.8 1.0

Fig. 12 Slip length of semi-infinite straight conduit

306
REGIONAL RISK ASSESSMENT OF ENVIRONMENTAL CONTAMINATION

FROM OIL PIPELINES

Susan D. Pelmulder^

Ronald T. Eguchi^

1. Staff Engineer, Dames & Moore, Los Angeles

2. Associate, Dames & Moore, Los Angeles

ABSTRACT

This paper presents a methodology for assessing the risk of environmental contamination

from oil pipeline leaks due to earthquakes. Risk is measured both as volume of oil released

and remediation cost. The methodology was developed for use on a regional scale and thus

relies on a limited amount of input data. Monte Carlo techniques are used to simulate

earthquake events, while a deterministic model is used to estimate the volume of oil

released at a particular site. A library of cost models is used to estimate the contamination

and resulting remediation cost based on the volume of oil released and the general site

conditions. This methodology has been implemented in a computer program, OILOSS, and

the results are presented as frequency of exceedence curves for volume of oil released and

cost of remediation. The methodology is applied to two crude oil pipelines near the New

Madrid Seismic Zone (NMSZ) and preliminary results presented. This study is being

sponsored in part by a contract with the National Center for Earthquake Engineering

Research (NCEER).

307
INTRODUCTION

There are currently many seismically-active areas in the United States with petroleum

pipelines. While there have been many incidents of piping to tanks breaking during

earthquakes, there have not been any major incidents in the United States involving

transmission lines. This has been in part due to the relatively short time frame that large

transmission Unes have been constructed and the few number of major earthquakes in

recent history in the United States.

In other countries, however, there have been significant losses resulting from petroleum

transmission pipelines damaged during earthquakes. Most notable is the loss associated with

the 1987 Ecuador Earthquakes of Richter magnitude 6.1 and 6.9 (Crespo, et al. 1987). In

these events, two areas of the Trans-Ecuador pipeline, 6.5 and 10 mi long, were severely

damaged. This resulted in the loss of at least 70,000 bbl of crude oil, complete disruption

of oil export, and major rebuilding costs.

With the increasing possibility of a major earthquake in the New Madrid Fault Zone, there

is also the possibility of damage to major pipelines carrying crude oil from the south to

refineries in the midwest. Loss of a single pipeline would not create a complete disruption

of oil flow to the refineries, however, it could have a significant impact. The losses may be

direct, such as environmental contamination, or indirect, such as business interruption losses.

The present methodology addresses the direct losses associated with environmental

contamination. Other study elements within the larger NCEER project are focussing on

other socioeconomic losses attributed to oil pipeline spills.

The approach used here is based on probabilistic methods. Another common approach for

assessing loss potential is to use a worst case or probable maximum loss (PML) approach.

In these methods, though, the likelihood of the assumed break locations and their associated

losses ever occurring are rarely estimated. A risk based approach, such as that presented

here, is preferable because each loss level is accompanied by a concrete estimate of the

likelihood of the loss occurring or being exceeded. This enables a realistic approach to

preparedness or mitigation planning.

The general approach and simulation procedure is first presented, followed by a description

of the contamination and cost estimation models. An example is then discussed. The paper

concludes with some comments on future applications.

APPROACH

In developing this methodology, there were three primary objectives:

1. the methodology should be applicable on a regional basis without excessive

computational or input requirements,

308
2. the models should utilize available data, but not be dependent on site-specific

information,

3. the output should provide probabilistic estimates of loss levels, rather than worst-case

values.

These objectives, which include a pragmatic approach to using regional seismic hazard data,

essentially dictate the choice of models used for estimating the volume of oil released, the

extent of contamination, and the associated remediation cost.

The general approach followed in this study was to use Monte Carlo techniques to simulate

earthquake events. Although the primary focus of this paper is on seismic events, both

earthquake and normal operational risks can be assessed using this approach. In the case

of seismic events, each simulation trial represents a possible outcome of the earthquake.

The results of the entire simulation allow us to represent the distribution of losses which

may occur from a single earthquake event. To obtain a distribution of losses for all earthquakes possible in the region, a series of events is simulated and the results combined

and weighted based on their probabilities of occurrence.

The procedure for estimating losses due to a single event is outhned in Figure 1. A library

of cost models is used to determine the remediation cost. This cost is estimated once the

appropriate environmental model has been selected (i.e. river crossing, flood plain, etc.) and

the volume of oil released has been estimated. The environmental and oil release models

are described in later sections of this paper. Because the cost estimates do not depend on

a particular event, they are evaluated prior to the simulation and accessed via data arrays.

Pipeline vulnerability models developed in Eguchi (1983) and updated in Eguchi et al. (1989) are used to determine the failure probability of each pipe segment that is exposed

to an earthquake hazard. For each simulation trial, a random number is selected and then

compared to the failure probability of a pipe element to determine if the pipe element has

broken.

Once the locations of all breaks for a particular trial are known, a deterministic "drain

down" model is used to estimate the volume of oil released at each location. This model

assumes that all oil originally above the break drains out, with the exceptions of oil trapped

in valleys, and oil blocked by valves and pump stations. Conservation of mass is maintained

such that the same oil can only leak out of one location. This type of model is in some ways

overly conservative because it does not consider breaks of different sizes or the time

required for the pipe to drain. However, the model does provide an estimate of the volume

which could leak out if the pipe were to break and the leak were uncontrolled. The drain

down model is also easily applied, that is, the only data required to estimate drain down

volume is the elevation at the endpoints of the pipe segments and the pipe diameter.

With the volume released at each location known and the appropriate environmental cost

309
model specified, the remediation cost can then be determined. The losses, both volume and

dollar, are aggregated for all pipe failures simulated in the analysis to determine the total

losses for the event. At this point, the simulation trial is completed and a new set of break

locations are generated. The process is continued until stable distributions of loss are

obtained. The number of trials required is dependent on the number of pipeline elements

and system failure probability. After all trials are completed, annual frequency of

exceedence curves are formed by normalizing the resulting frequency curves by the number

of trials performed, and then unconditionalizing these curves by the annual probabiHty of

the earthquake.

LIBRARY OF COST MODELS

A library of cost models was used to determine the dollar loss associated with each leak.

These models estimate both the extent of environmental contamination and the cost of

remediation. Five generalized models were developed to approximate the various types of

contamination which may occur. The appropriate library model for each pipe segment is assigned based on the general topography of the area, depth to ground water, and proximity

to surface water.

The contamination models use Darcian flow to estimate the vertical extent and rate of oil

migration in soil. Using this analytic model, an estimate of the scale of ground water

contamination can be made. Surface water is contaminated if the break is near a river, lake, or wetlands. Estimates of remediation costs for soil, ground water, and surface water were

obtained from experts in the field. The models were formulated such that the type of

contamination and its associated cost could be estimated based on the library model

specified and the volume of oil released.

Even with these relatively simple analytic models for contamination, there are many

parameters which significantly effect the remediation cost. Furthermore, to be general, the

models must be applicable for any season of the year and a variety of soil conditions. To

obtain an estimate of the average cost for a given library model and volume released, event

trees were used. The parameters in the event trees included variables such as depth to

water table, soil permeability, oil type, response time, and cost schedule. Each variable was

allowed to take two or three states to approximate its range of values, and a probability was

assigned to each state. The cost associated with the parameters in each branch of the tree

was evaluated along with its likelihood of occurrence. For each model, the average or expected cost of remediation was obtained for the range of oil spill volumes specified.

These arrays were used in the simulation procedure.

310
APPLICATION OF METHODOLOGY

The methodology has been applied to two major crude oil pipelines near the NMSZ.

Modified Mercalli Intensity isoseismals for a M=8.6 earthquake anywhere along the NMSZ

were developed by Algermissen and Hopper (1984). MMFs for an event anywhere along

the seismic zone is approximately equivalent to a single earthquake with a very long rupture

length, or a combination of events, such as the 1811-1812 series of earthquakes. This map

was digitized and used as the strong ground shaking scenario. Figure 2 shows the strong

ground shaking in the study area. A single event of this magnitude (MS > = 8.3) has a

return period of 550 ( + /- 125) years and 0.3-1.0 percent probability of occurrence by the

year 2000 CE (Johnson and Nava, 1984). For this example a 0.5 percent probability of occurrence by the year 2000 is assumed.

A significant seismic hazard in the Mississippi Valley and along rivers is liquefaction-induced

ground failure. Areas of moderate to high liquefaction potential in a large earthquake were

mapped for seven states in the Central United States by Obermeier (1985). No distinction

was made on these maps between areas of liquefaction and landslide, or areas of greater

and lesser potential. Tbese maps were digitized and combined into a single map. Figure

3 shows the areas of moderate to high liquefaction potential included as seismic hazard

input to the simulation.

The Shell Capline and Mobil line number 68 were selected to demonstrate the methodology.

These pipelines are shown in Figure 4. The Shell Capline is a 40 in diameter pipeline built

in 1968 from API 5LX-X52 grade welded steel pipe with arc welded joints (Ariman et al., 1990). The Mobil pipeline is 20 inches in diameter in the south and 18 inches in diameter

in the north. This pipeline was built around 1948 from grade B steel with welded joints.

The results obtained for this example are preliminary and should be viewed as such. The

annual frequency of exceedence of the volume of oil released is contained in Figure 5. This

volume is the sum of spill volumes from all leaks occurring in a single event. The range of

total volumes from this scenario is 150 thousand to 2350 thousand barrels, with an expected

volume of 400 thousand barrels. While this would be quite a large volume for a single

location, the expected number of leaks in this scenario is 87, and the expected spill volume

at a single leak site is 4700 bbl. The maximum frequency on this curve, 0.005, is the

frequency with which at least one spill occurs. Because this is a severe scenario, at least one

leak occurred in every simulation of the event. Therefore, the maximum frequency is also

the probability of the event.

Dollar losses for remedial measures were also estimated for this scenario. Figure 6 contains

the frequency of exceedence of dollar losses. The range of possible losses is 30 million to

2.4 billion dollars. This range is very large because of the large difference in the cost

models between remedial measures for surface water and those for soil. In a simulation

where an extraordinarily large number of leaks occurs, and many of them are in flood plains or rivers, the cost of clean up can be quite high. However, many more moderate than

311
extreme cases are possible and the expected loss given the event is 310 million dollars. The

expected loss at a single leak site is 3.6 million dollars.

CONCLUSIONS

The importance of using a probability or risk-based analysis can clearly be seen from this

example. If a worst case analysis had been performed it is possible that losses in the 600

thousand bbl and 2 billion dollar range would have been determined, without an estimate

of the likelihood they would actually occur. Compared with the aimual frequency of

exceedence curves, it is seen that the worst case analysis may produce loss values with

frequencies three to four orders of magnitude less than the frequencies of the expected

values.

This example also demonstrates the large variation in both spill volumes and remediation

costs which can occur in a given earthquake. The present methodology provides estimates

of the frequency of exceedence for the entire range of volumes and costs. Using these

curves, the risk associated with the operation of existing pipeline systems or the design of

new systems can be quantified.

ACKNOWLEDGEMENTS

This research was funded in part by the National Center for Earthquake Engineering

Research. The authors wish to thank Drs. Barclay Jones of Cornell University and , and

NCEER, Masanobu Shinozuka of SUNY and NCEER for their support in this project. The

authors would also like to thank John Robinson of Dames and Moore for providing input

into the environmental modeling of oil pipeline spills.

APPENDIX

1 bbl (barrel) = 42 U.S. gallons = 159.0 liters

1 mi = 5280 ft = 1609 m

REFERENCES

Algermissen, S. T., and M.G. Hopper (1984) "Estimated Maximum Regional Seismic

Intensities Associated With and Ensemble of Great Earthquakes that Might Occur Along

the New Madrid Seismic Zone, East-Central United States," Miscellaneous Field Studies

312
Map MF-1712, U.S. Geological Survey.

Ariman, T., et al. (1990) Pilot Study on Seismic Vulnerability of Crude Oil Transmission

Systems, NCEER Technical Report NCEER-90-0008.

Crespo, E., et al. (1987). 1987 Ecuador Earthquakes of March 5, 1987: EERI Special

Earthquake Report. EERI Newsletter, Vol 21, No 7, July.

Eguchi, R.T. (1983) "Seismic Vulnerability Models for Underground Pipes," Earthquake

Behavior and Safety of Oil and Gas Storage Facilities, Buried Pipelines and Equipment,

PVP - Vol. 77, ASME, New York.

Eguchi, R.T. et al. (1989) "Early Post-Earthquake Damage Detection for Lifeline Systems,"

Proc. 3rd U.S.-Japan Workshop on Earthquake Disaster Prevention for Lifeline Systems,

May 11-13, Pubhc Works Research Inst., Tsukuba Science City, Japan.

Johnson, A. and S.J. Nava (1984) "Recurrence Rates and Probability Estimates for the New

Madrid Seismic Zone," in Proceedings of the Symposium on 'The New Madrid Seismic

Zone," P.L. Gori and W.W. Hayes , eds., USGS Open File Report 84-770.

Obermeier, S.F. (1985) Plates 1-7, in Estimation of Earthquake Effects Associated with

Large Earthquakes in the New Madrid Seismic Zone, M.G. Hopper, ed., U.S. Geological

Survey, Open File Report 85-457.

313
INPUT SYSTEM DATA

library of Cost Model Arrays

Pipe Element Geometry

Hazard Data

T

DETERMINE FAILURE PROBABILITIES FOR EACH ELEMENT

RUN LEAK SIMULATION

Determine Break Locations

Determine Oil Release Volume

Determine Associated Cost

of Remediation

no

Sum Costs from All Break Locations

Sum Volumes from All Break Locations

Record Results

X

FORM ANNUAL FREQUENCY OF EXCEEDENCE CURVES FOR

VOLUME OF OIL RELEASED AND REMEDIATION COST

FIGURE 1. Procedure for Simulating Events to Estimate

Frequency of Exceedence Curves

314
I
Figure 3. Areas of Moderate to High Liquefaction Potential in the New Madrid Seismic

Zone During a Major Earthquake. (Digitized from Obermeier, 1985)

316
Figure 4. Pipelines Studied

317
10 z

2 -

1 0 -|—I—i—I

\—

I

\—\—\—I

\—\—I—I—I—

I

\—I—I

\—\—\—\ I I

I O.OE+000 5.0E+005 1.0E+006 1 .5E+006 2.0E+006 2.5E+006

Volume Loss (Barrels)

Figure 5. Frequency of Exceedence of Total Spill Volume in a M^or Event in the New

Madrid Seismic Zone

318
Figure 6. Frequency of Exceedence of Dollar Loss

319

DAMAGE ASSESSMENT OF LIFELINE SYSTEMS

IN JAPAN

Masanori Hamada

Professor

Dept. of Civil Engineering

School of Marine Science and Technology

Tokai University, Shimizu, Japan

ABSTRACT

This paper first introduces the current status of damage assessment of

lifeline facilities, including the estimation of the loss of function. The

methods of the estimation of earthquake motion on the bedrock as well as on

the ground surface were outlined, and a general flow for the evaluation of

the damage probability of the lifeline facilities is shown.

Secondly, the present paper describes the future research subjects such as dynamic response of soft ground, liquefaction-induced permanent ground

displacement and effects of permanent ground displacement on the lifeline

facilities, which shall be studied for the damage assessment with a high

accuracy.

INTRODUCTION

Large-scale development projects are now proceeding on the waterfront in

many major Japanese cities, including Tokyo and Osaka. These waterfront

projects are often conducted on soft ground reclaimed ground from the sea or

a river. In the 1989 Loma Prieta earthquake, lifeline facilities were

seriously damage as a result of liquefaction of reclaimed land in the San

Francisco Bay area. The Loma Prieta earthquake taught us the importance of

earthquake resistant design of structures on and in reclaimed ground.

Accordingly, local governments such as Tokyo Metropolitan Government and the

companies providing lifeline services, such as electricity and gas

companies, are now conducting assessments of the damage resulting from a strong future earthquake. Pre-earthquake measures to reinforce facilities

and post-earthquake recovery strategies are also being investigated based on the results of the damage assessment. In these studies, the effects on lifeline facilities of liquefaction-induced ground displacement are also

being examined. This paper describes the current status of damage

321
estimation of lifeline facilities, including estimations of the loss of

function and the research subjects still to be solved in making these

estimations in Japan.

DAMAGE ASSESSMENT OF LIFELINE FACILITIES AND SYSTEM FUNCTION

The damage estimation of lifeline facilities, the loss of the function, and

the recovery process follows the work flow shown in Figure 1. Lifeline

facilities are generally distributed over a wide area, so seismic activity

is surveyed for the whole area and an anticipated earthquake, the subject of

the study, is determined based on the survey. For cities on the Pacific

coast, such as Tokyo and Osaka, an undersea earthquake of the magnitude 8

class and an inland one of magnitude 7 class with the hypocenter right under

a city, are sometimes assumed. If the earthquake under the ocean is

assiamed, the effects of tsunami must be taken into consideration because

some lifeline facilities such as thermal power stations are located on the

coast

.

Effects of Tsunami

Estimation of Ground

Failure; Liquefaction and Slope Sliding

Policy for Reinforcement

of Facilities Before the Next Earthquake

Survey on Earthquake Activity and Determination of Earthquake for Study

(Attenuation Formula)

Estimation of Earthquake

Motion on Bedrock

Estimation of Earthquake fvlotion on Ground Surface and in Ground

Estimation of Damage to Lifeline

Facilities I

Estimation of Loss of System's Function

Simulation of Recovery Process

(Zoning and Classification

of Ground Condition)

Establishment of Strategy

for Recovery After an

Earthquake

Figure 1 General Flow of Damage Estimation of Lifeline Systems

322
The earthquake motion on the bedrock throughout the area on which lifeline

facilities are distributed is estimated by using attenuation formulae. In

this case, correct estimation of the earthquake motion in the neighborhood

of earthquake faults will be one of the important subjects, for the reason described later.

1

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Figure 2 Example of Meshes for Calculation of Ground Response in Tokyo

Metropolitan Area (1 km Mesh)

The next step is to estimate the earthquake motion on the ground surface as well as in the ground by dynamic response analysis, the input for which is

the earthquake motion on the bedrock. Besides acceleration, velocity, and

displacement, it is required to determine the relative displacement and

strain in order to estimate the damage to buried lifeline facilities. Since

lifeline facilities are distributed over a wide area, the area of interest

is generally divided into meshes with a size of 1 kilometer to 500 meters,

and the earthquake motion for each mesh, where the ground conditions is

assumed to be uniform, is calculated. For example, the ground in Tokyo area

is divided into about 10,000 meshes as shown in Figure 2 with 150 kinds of

ground conditions.

323
Based on the calculated earthquake motion on the surface and in the ground,

the probability of liquefaction and slope sliding is examined. Since many

areas of Japanese large coastal cities are constructed on reclaimed land,

the exact estimation of liquefaction potential is one of the key subjects

for damage assessment of lifeline facilities. The damage to lifeline

facilities is estimated based on the calculated earthquake motion, by taking

into consideration the effects of ground failure such as liquefaction.

The damage degree to facilities is generally represented as a probabilistic

value. For example, the damage degree of buried pipes is given as the

average number of failures per unit length of pipe or as the damage

probability at connection point with other structures such as the manhole.

As for the effects of liquefaction, we must consider the effect of the

permanent ground displacements, subsidence and heaving of ground and

floating up of manholes. In places where lifeline pipes cross a river, the

effects of the subsidence of the embankment behind bridge abutments must

also be taken into consideration.

The following two methods can be used to obtain a damage probability. The

first method is by empirical formulae obtained by statistically analyzing

the damage caused to lifeline facilities in past earthquakes. For example,

the following empirical formula is proposed for the buried pipes.

Rf = Cq • Cl • Cp • Cj; • R s

Rf : Damage probability of buried pipes

Rg: Standard damage probability

Cq: Factor by ground condition

Cl: Factor by liquefaction

Cp: Factor by pipe's material and diameter

Cg: Factor by strength of earthquake motion

Figure 3 shows damage rate of buried pipes (mean number of the failure

points per 1 km) obtained from 1971 San Fernando and 1978 Miyagiken-Oki

earthquakes. From these data the standard damage probability Rg can be

determined. However, most of the damage resulting from these earthquakes

were caused to pipes with a relatively small diameter and low strength, so it is necessary to make a correction to the standard damage probability

according to strength and ductility when it is applied to strong,

large-diameter pipes. Recently, large-diameter steel pipes or ductile iron

pipes with flexible joints have come into wide use for lifeline system

mains. It is one of the most difficult subjects to determine a correction

factor suitable for these pipes, since almost no actual damage data are available

.

The second method of the evaluation of the damage probability of facilities

is to compare the stress, the strain and the deformation which are calculated based on predicted earthquake with the ultimate strength of the

facilities. Figure 4 shows the process of calculating the damage

probability for buried pipes. Besides the relative ground displacement and

the ground strain resulting from earthquake motion, the permanent ground

324
displacement due to liquefaction is taken into consideration in the

calculation of the stress, the strain and the deformation of buried pipes.

The functionality of lifeline system after an earthquake is evaluated based

on the damage assessment of the facilities. A lot of numerical methods of

network analysis have been proposed. However, practical networks of

lifeline facilities consists of an enormous number of elements and such an analysis covering all elements is actually impossible. Thus, to achieve the

objectives, some simplifications are conducted by taking into account the

characteristics of the network. An electricity supply substation, for

example, consists of many transformers, circuit breakers, and other

components, but is substituted by a simple system with fewer elements upon

the judgement of experts.

The post-earthquake recovery strategy right after an earthquake is studied

on the basis of estimated damage to facilities and the function. The

recovery process is simulated in accordance with several probable recovery

strategies, and based on the simulation, the best strategy is chosen by

referring to expert's opinions. The pre-earthquake policy for the

reinforcing facilities is also determined by the damage estimation and by

the simulation of recovery process.

6.0 5.0

E 4.0

ISS) 3.0

0)

eg

2.0

I .5

1 .0

0.5

Niigata

-4

X 1971 San Fernando

• Cast Iron Pipe ^ Ductile Cast Iron Pipe

Noshiro ^ Steel pipe

O Asbestos Cement Pipe

PVC Pipe

> Miyagiken-Oki

ICQ 200 300 400 500

Maximum Acceleration on Ground Surface

(gal)

Figure 3 Water Pipe Damage Rate in 1971 San Fernando

and 1978 Miyagiken-Oki Earthquake

325
Estimation o( Earthquake

Motion

1 Y

Estimation of Relative Ground

Displacement and/or Ground

Estimation of Ground Displace- ment by Liquefaction; Lateral Movement, subsidence and

Heaving

Calculation of Deformation, Strain and Stress of Buried Pipes

Estimation of Damage

Probability

Estimation of Ultimate Strength of Buried Pipes and Cables >

Figure 4 General Flow for Estimating Damage Probability

for Buried Pipes

FURTHER SUBJECTS ON EARTHQUAKE RESISTANCE

OF LIFELINE SYSTEMS

The areas needing future study to enable accurate damage estimation of

lifeline facilities and their functions are described below.

Earthquake Motion in the Neighborhood of Fault

Many attenuation formulae, which take earthquake magnitude and epicentral or hypocentral distance as functions for estimating earthquake motion, have

been proposed. Some examples are shown in Figure 5. Most of the earthquake

records which were used to develop these attenuation formulae were collected

relatively far from the earthquake fault during large or medium-magnitude

earthquakes, or were measured during small-magnitude earthquakes.

Earthquake motions which are recorded near faults are insufficient to

establish a reliable attenuation formula. Thus, ground motions within an epicentral distance of 0-20 km due to earthquakes with a magnitude of 7-8 are estimated by extrapolation.

326
(gal)

Epicentral Distance (km)

Figure 5 Attenuation Formula for Estimation of Ground Motion

When an inland earthquake occurs, some facilities are inevitably located in

the fault zone because lifeline facilities are distributed over a wide area. The damage probability for facilities in the fault zone is high, and the

degree of damage to those facilities has a great influence on the overall

functioning of the system. Therefore, one of the most important tasks is to

estimate correctly the earthquake motion in a fault zone for the damage

estimation of lifeline facilities.

Figure 6 shows an example of a maximum acceleration map for the ground

surface. This map was used to estimate the damage to lifeline systems

resulting from a future earthquake in the metropolitan area. The maximum

acceleration was calculated by non-linear dynamic analysis. According to

this map, the maximum acceleration in Shinjuku Ward, on the diluvial

plateau, is greater than that in Koto Ward along the Siamida River on alluvial low land. This map shows that the acceleration on soft ground is

less than that on firm ground.

Dynamic Response of Soft Ground

In the Loma Prieta earthquake, the acceleration on reclaimed land around San

Francisco Bay was two to three times greater than that on firm ground. And

in the 1985 Mexico City earthquake, too, acceleration was amplified

significantly on land reclaimed from the lake in the city and many tall

buildings were seriously damaged.

327
140°

Figure 6 Maximum Acceleration Map of Tokyo Metropolitan Area

Figure 7 shows maximum accelerations on the ground surface and on the

bedrock as measured on reclaimed land around Tokyo Bay. The maximum

acceleration on reclaimed land is two to three times greater than that on

the bedrock. It seems that the maximum acceleration given in Figure 6

somewhat contradicts the actually measured accelerations in Figure 7.

The results of a dynamic analysis of reclaimed land in Tokyo, shown in

Figures 8 and 9, illustrate this contradiction. Figure 8 shows the ground

conditions and the numerical model while Figure 9 shows the acceleration on the surface calculated by non-linear response analysis using the R.O. model.

The calculated maximum acceleration on the surface is 121 Gal, assuming the

maximum acceleration on the bedrock to be 100 Gal. Some amplification of

earthquake motion from the bedrock to the ground surface can be seen. However, the surface acceleration becomes 156 Gal, if the maximum

acceleration on the bedrock is 200 Gal, so the amplification factor is less

than 1.0. The reason for this is that, for a larger acceleration on the

bedrock, the natural period of the ground increases and the damping effect

is enhanced by the more significant influence of non-linear soil

characteristics. Consequently, the accelerations on soft ground are estimated to be less than those on firm ground, as shown in Figure 6.

328
;suU|— D

Majdmum Acceleration on Bedrock (Horizontal Direction)

Figure 7 Maximum Acceleration on the Ground Surface and Bedrock Recorded

on Reclaimed Land in Tokyo Bay Area

The probable reasons for the lower acceleration on the soft ground are as follows

.

1) Evaluation of soil properties for the analysis is not adequate. In

particular, there may be problems in evaluating the damping

coefficient

.

2) The numerical model is not adequate. One-dimensional model such as SHAKE is generally used for the calculation of the ground acceleration.

In these numerical models, the effect of seismic waves propagating in a horizontal direction, which are caused by variations in ground

conditions are not taken into consideration.

In order to carry out accurate damage estimation of lifeline facilities, it

is critical that earthquake motion of soft ground such as reclaimed land be

evaluated. Research activity on this subject should be promoted by

utilizing the observed earthquake motions on soft ground, such as those

recorded during the Loma Prieta earthquake.

329
Liquefaction-Induced Permanent Ground Displacement

The author and his research team reported that liquefied ground was displaced as much as several meters in the horizontal direction, depending

on topographical conditions, at the time of the 1983 Nihonkai-Chubu

earthquake.!) Since then research case studies of liquefaction-induced

ground displacements caused by eight earthquakes in Japan and the U.S. have

been conducted by the Japan-U.S. joint research team.^) »^) The mechanism

of liquefaction-induced ground displacement has been investigated by shaking

table test. However, no mechanism which gains a consensus of researchers

has been found so far.

Depth

(m)

-10 -

-30

Fino Sand

sat

Sondy Silt

Sandy Clay

Sand

Fine Sand

Hard Cloy

Torlinry Layer

Thickness

(m)

Shcnr Wave

Velocity (m/s)

Tertiary

I.oycr

3.8

2.0

6.3

10.8

Density

1.50

Numerical Model

Figure 8 Ground Conditions and Numerical Model for Dynamic Response

Analysis (Alluvial land in Tokyo)

1

330
Max. Acceleration on Ground Surface (121 Gal)

Max. Acceleration on Bedrock (100 Gal)

(a) CASE I

150 Max. Acceleration on Ground Surface (156 Gal)

200

-200

Max. Acceleration on Bedrock (200 Gal)

? 1 2 3 4 5

9 7

e 9 ID II 12 13 14 IS ]B 17 IB 19 20

TIME CSEC)

(b) CASE II

Figure 9 Response Acceleration on Ground Surface

Only the following empirical formula has been proposed;

D = 0.75 VE y/Q

Liquefaction-induced ground displacement (m)

Thickness of liquefied soil layer

Gradient of ground surface or of liquefied soil layer (Z)

Estimating the effects of liquefaction-induced displacements on lifeline

facilities, especially on buried pipes, requires accurate estimates of the

displacement magnitude, its direction and pattern. To make this information

available, the mechanism of ground displacement needs to be fully clarified.

Model tests using shaking tables are now being undertaken by several

institutes in Japan, while work on numerical models to calculate the

permanent ground displacement is proceeding.

Effects of Permanent Ground Displacement on Lifeline Facilities

Many buried pipes and foundation piles were damaged by liquefaction-induced

ground displacement during the 1964 Niigata and 1983 Nihonkai-Chubu

331

)
earthquakes. The effects of liquefaction on lifeline facilities are as follows

.

1) Settlement and inclination of structures due to reduction of the

ground's bearing capacity.

2) Floating of underground structures such as manholes due to buoyancy in

the liquefied soil.

3) Liquefaction-induced permanent ground displacement.

Effects 1) and 2) are already taken into consideration in the

earthquake-resistant design of facilities, but effects of permanent ground

displacement 3) are at present not considered.

When large permanent ground displacements, with a magnitude of several

meters, are considered in the earthquake-resistant design of buried pipes

two matters become a problem. One is whether "the seismic response

displacement method," which has conventionally been used for the design of

underground structures, is applicable or not. And if it is applicable,

there is also the problem of how to evaluate the coefficient of the subgrade

reaction of partially liquefied ground.

The other is the evaluation of the ultimate strength of facilities. It is

impossible to design the facilities using the conventional allowable-stress

method when the permanent displacement is several meters, and information on the ultimate strength of lifeline facilities such as buried pipes is

insufficient at present.

The former problem has been studied in an experiment on a pile foundation

model in liquefied soil, and it was reported that the force acting on the

pile during lateral movement of liquefied soil is similar to the drag force

in a liquid. The second problem is now being studied by laboratory tests on piles and pipes.

CONCLUSIONS

In this paper, the current status of damage estimation of lifeline

facilities in Japan and problems needing solution in future are described.

As stated in the introduction, large-scale waterfront projects have already

progressed greatly in major cities. To create an earthquake-proof urban

society, the study of damage to lifeline facilities must proceed much more quickly

.

References

1) M. Hamada et al.. Study on Liquefaction-Induced Permanent Ground

Displacements, Association for the Development of Earthquake

Prediction, November 1986, Tokyo, Japan.

332
2) T.L. Youd and S.F. Bartlet, U.S. Case Histories of Liquefaction-Induced

Ground Displacement, Proceedings of 1st Japan-U.S. Workshop on Liquefaction, Large Ground Deformation and Their Effect on Lifeline

Facilities, November 1988, Tokyo, Japan.

3) M. Hamada, K. Wakamatsu and S. Yasuda, Liquefaction-Induced Ground

Displacement during the 1948 Fukui Earthquake, Proceedings of 2nd

U.S. -Japan Workshop on Liquefaction, Large Ground Deformation and Their

Effects on Lifelines.

4) T.D. O'Rourke, B.L. Roth and M. Hamada, A Case Study of Large Ground

Deformation during the 1971 San Fernando Earthquake, Proceeding of 2nd

U.S. -Japan Workshop on Liquefaction, Large Ground Deformation and Their

Effects on Lifelines.

333
1
VI. POST-EARTHQUAKE RESPONSE/

DAMAGE DETECTION

"Data Acquisition and Emergency Response System for

City Gas Pipeline Operation During a Major Earthquake"

y. Yoshikawa

"Damage Inspection Systems Immediately after an Earthquake"

K. Kawashima, H. Sugita. K. Kanoh

"Estimation of Degree of Anxiety Felt by

People in Underground Urban Spaces During Earthquakes"

E. Saito, H. Ikemi. H. Nakano, M. Nakamura

"Performance of Lifeline and Emergency Response in

Watsonville, California to Loma Prieta Earthquake"

J. Isenberg

"Strategies for Repair and Restoration of

Seismically Damaged Gas Pipeline Systems"

M. Shinozuka, M. Murata, T. /wata

335

DATA ACQUISITION AND EMERGENCY RESPONSE SYSTEM

FOR CITY GAS PIPELINE OPERATION DURING A MAJOR EARTHQUAKE

Yulchl Yoshikawa

Senior Manager

Center for Disaster Management and Supply Control

Tokyo Gas Co. , Ltd.

Abstract

Tokyo Gas more narrowly divided its entire service area by block

and sub-block to preclude the possibility of a secondary disaster

in the event of major earthquake, and introduced a new remote

controlled system capable of limiting service shutoff solely to

badly damaged blocks.

Tokyo Gas has recently developed a data acquisition system capable of transmitting real-time seismic and damage information to

its headquarters by means of a multiple radio telemeter system.

This enables the company to render timely operations in the event

of emergencies, service shutoff to badly damaged blocks.

Introduction

The Tokyo Metropolitan area is characterized by an extreme concentration of population, economic and industrial production, and

information--rare among the cities of the world.

This area, however, is threatened by a higher possibility of

earthquake than any other cities of Japan where seismic activity

is brisk. For this reason, public lifeline utilities commissioned

to support urban functions are required to make extra safety

provisions against damage from future earthquakes.

Above all, city gas utilities are publicly obligated to take

cautious steps to preclude the possibility of any secondary

disaster resulting from seismic damage inflicted on the gas service system. Because the city gas pipeline network spreads over a

wide area and consists of a variety of structures and buried

conduits, exact assessment of seismic damage is difficult and

time consuming.

337
Tokyo Gas has divided its service area into blocks that are

remote-controllable by a multiple radio telemeter system. The

system stops gas supply to selected blocks according to the

intensity of damage inflicted, and enables uninterrupted gas

supply for the unaffected areas. , Public city gas utilities, however, are required to maintain a

stable supply even in the event of a major earthquake, and to

make a decision for or against service shutoff after prompt and

exact assessment of seismic behavior and damage information by

block. Therefore, the construction of a system is under way that

collects in real-time such seismic information and makes immediate decisions in emergencies.

The next chapter gives a brief system overview.

Gas Production and Service Facilities

Tokyo Gas supplies gas to Tokyo and its neighboring cities,

catering to about 7.2 million clients over a service area of

about 2,500 km^ (Fig. 1).

Gas supply is classified by high pressure, medium pressure A,

medium pressure B, and low pressure, with a total pipeline length

of about 39,000 km (Fig. 2). High-pressure gas delivered directly

from the plant is reduced to medium pressure A by at regulator

stations, and then down to medium pressure B by district governors, and finally to low pressure by 4,000 district governors

before being supplied to customers.

The Center for Disaster Management and Supply Control at the Head

Office (hereafter called the "headquarters") radios operating

instructions to the plant. Headquarters by means of radio is able

to control operations, as well as the pressure and flow rate of

gas holders and governor stations. Communication and computer

facilities assist in this effort (Fig. 3)

.

Simultaneously, headquarters is in charge of supervision of gas

production and gas supply in the event of an earthquake.

Provisions for Earthquakes

Prevention of secondary gas-induced disasters

o Main equipment and facilities are designed in robust construction for high seismic resistance.

o Timely service shutoff by block/sub-block is ensured in the

event of an earthquake.

338
Uniterrupted gas supply for the unaffected areas

o Where service blocks are damaged in different severity, the

system isolates severely damaged blocks and stops service to

these blocks

o Maximum efforts will be made to continue service to undamaged

or slightly damaged blocks.

Prompt gas- suspension recovery

o Except for badly damaged blocks, maximum efforts will be made

to accelerate recovery of moderately damaged blocks.

Subdivision of Blocks to Minimize Service Shutoff

Division of gas pipeline network by block/sub-block

Tokyo Gas caters to a broad service area where seismic damage has

a regional difference according to the location and intensity of

the quake and the properties of the ground involved.

Allowing for maximum availability of consumer service, time-consuming recovery work, and manpower requirements, it is preferable

to partition the service area into the smallest possible blocks

for flexible service upkeep or shutoff by block, depending on the

severity of damage to each one.

Therefore, allowing for regional characteristics and the service

station's management area, a gas pipeline network is classified

in two different blocks by pressure of gas supplied.

(1) "King blocks" (for medium-pressure pipelines)

The medium-pressure pipeline network is divided into nine King

(K) blocks (Fig. 4) , each block serving several-hundred thousands

of customers. K blocks have service facilities such as plants and

governor stations by block and are provided, along each block

boundary, with valves remote-controllable by radio from headquarters in emergencies to facilitate service shutoff by selected

blocks.

(2) Large (L) blocks for low-pressure pipelines

In the event of earthquakes immediately below, where damage is

localized, K block-level system shutoff can unnecessarily interfere with customer service. Therefore, a network of low-pressure

pipeline is subdivided into 100 L blocks (Fig. 5), each of which

remains separated from its adjacent block and has its own district governor incorporating an SI sensor to permit block-byblock service shutoff according to seismic intensity.

339
Shutoff by customer

Customers' gas meters incorporate microprocessors. As soon as a

seismic sensor detects a substantial earthquake, the gas meter

shuts off gas flow and stops gas supply to customers. As of now,

67% of customers use microprocessor built-in gas meters.

This type of gas meter automatically shuts off gas flow where the

flow rate is abnormal or when continuous use of gas is disclosed

over extended hours.

Data Acquisition Regarding Seismic Behavior and Damage

In the event of an earthquake, the system not only promptly collects information on seismic behavior and damage inflicted and

isolates badly damaged blocks from others, but also invokes emergency operations, including service shutoff to damaged blocks to

preclude the possibility of a secondary disaster.

The following paragraphs present a network of communication systems and the scope of information to be collected.

Communication network

An earthquake can disrupt wire communication circuits .or keep

them "busy," thereby disabling data acquisition and telecontrols.

Accordingly, Tokyo Gas implements a network of multiplex radio

communication systems (Fig. 6). A private, looped radio communications system is laid between headquarters and major service

facilities including plants, service stations, pressure-regulating stations, governor stations, etc.

This system monitors gas pressure, flow rate, etc. at these service footholds as well as collecting operating data and information. Where the system detects any serious damage to a block,

remote-controlled K block valves are immediately shut and gas

flow is stopped.

Service stations have access to field damage information by means

of mobile or portable radio communication equipment.

Data Acquisition

(1) Seismic information system

The service area is equipped with 31 seismographs and SI sensors-

-an average of three to five per K block--and the moment any of

these seismographs detects an acceleration exceeding five galileos, the acceleration and SI values are transmitted to headquarters by telemeter.

340
Telemetering is made through the communication network, and headquarters can collect entire data within four minutes. Upon receipt of these seismic data, headquarters preferentially displays

acceleration and SI value distribution on the CRT screen to facilitate assessment of seismic intensity, rough estimation of damage, and distribution of damaged areas.

(2) Seismic Data Acquisition at L blocks

In each L block, telemetering and telecontrol points (operating

about 300 slave telecontrol points) are installed on three representative regulators so that the service station can acquire

seismic data (acceleration and SI values, service shutoff, and

pressure). The points supplement seismic information on K blocks.

(3) Damage Data Acquisition

(a) Information from service stations

The engineers of each service station patrol an affected area

after an earthquake and operate remote monitor TV cameras installed at the service station to collect information relating to

damage to buildings and structures, fire, gas leakage, etc. This

information is transmitted to headquarters by radio.

(b) Other information

We have also established a system capable of collecting a broad

range of seismic damage information over a large service area as

follows

o Wide service area damage data acquisition by helicopter, which

stands by for emergency operations around the clock

o Wide service area damage data acquisition by remote-monitor TV

cameras installed at headquarters and service stations

o Mass media information transmission by TV and radio

o Disaster control agencies (Tokyo Metropolitan Government, Fire

Defense Agency, police stations, and National Land Agency)

o Patrol information

Emergnecy Control System

In the event of a major earthquake, headquarters will take the

following emergency measures based on information on seismic

intensity, damage, etc.

Headquarters operates around the clock and is staffed with five

operators responsible for emergency decisions and operations.

341
Identification of damagrcd K blocks

Acceleration and SI values are radioed from 31 telemetering and

other points of the service area to headquarters for display on

the CRT screen. This facilitates analysis for identification of

damaged blocks (Fig. 7)

.

K block based operation

o If a given K block records an acceleration of more than 250 gal

or an SI value exceeding 25 kine in two or more locations, the

system radio transmits information on damage to the affected

blocks to the applicable service station.

o The system then shuts off all the K block valves by telecontrol

to Isolate them from other K blocks.

o The system also reduces the pressure of gas supplied to the

service area from the plant and governor stations.

Monitoring of K blocks

The flow-rate assessment system checks pipelines for gas to find

if a medium-pressure pipeline network in a K block has been badly

damaged. The system compares preseismlc and postselsmic flow

rates for possible gas leaks in excess of a prescribed threshold

value (currently, 100,000 m^/H) including an error.

Flow-rate assessment system

Qt > Qo (1-Ka) + Ql: Warning

Postselsmic flow rate

Preseismlc flow rate

Household supply by block

"microprocessor built-in gas meter" diffusion rate

Projected leaks (threshold value: lOO.OOOm^ in

terms of flat rate)

Service shutoff to K blocks

o If the system indicates abnormal flow rates, but fault recovery

is impossible at the discretion of the service station

concerned, the affected plant and governor station stop supply

to the affected K block.

o Steps are also taken to preclude the possibility of a secondary

342
disaster by venting medium-pressure gas into the air through

vent stacks installed in K blocks.

FUTURE PLANS

In the event of an earthquake in a major urban location such as

the Tokyo Metropolitan area, the city gas service system as an

urban infrastructure works to prevent a secondary disaster by

means of service shutoff to the damaged K block as soon as the

severity of damage is determined.

Accordingly, Tokyo Gas is involved in the development of a realtime pipeline-failure estimation system designed to determine the

severity and distribution of damage to gas pipelines and customers' facilities based on information transmitted from seismographs and SI sensors.

This system displays mapping data combined with disaster information and damage estimation on CRT screens. This helps disaster

system operators make intuitive decisions. The system is configured with four major features that process three types of realtime Information, ground information for city gas-supplied areas,

and other associated information (Fig. 8). Major system functions : Real-time Information collection (telemeter-aided seismic data

acquisition over a wide area)

o Acquisition of SI sensor data by 300 telemetering and

telecontrolling points in L blocks

o Acquisition of data monitored by ten accelerometers buried at

basement depth in the block

o Acquisition of data monitored by liquefaction sensors

Projection of damage

o Estimation of potential damage based on SI values

o Estimation of epicenter location and potential damage based on

the epicenter information

o Estimation of potential damage to structures and buried pipes

o Estimation of severity of ground liquefaction

Graphic representation of information

o Graphic display of real-time information

o Graphic display of potential damage information

343
Epilogue

Tokyo Gas is commissioned to supply gas to the Tokyo Metropolitan

area, which is characterized by sophisticated and complex urban

functions and structures. The company has a compelling social

obligation to prevent secondary disasters in the event of an

earthquake, and must promptly exert all means to enable the restoration of public utilities.

To meet these requirements, the critical point is how and rapidly

damage can be remedied. To achieve this, it is extremely important to commercialize the real-time pipeline-failure estimation

system that supports emergency decision-making. For this purpose,

Tokyo Gas will strive diligently for the timely completion of

this system.

References

SI sensor

To determine the effects of ground motion upon structures, it is

necessary to assess how intensively such motion can vibrate the

structures

.

One of the major barometers for this is the "velocity response

spectrum." Most structures range from 0.1 to 2.5 sec. in natural

periods. G. W. Housner defines mean spectrum intensity (SI value)

as a major indicator of the intensity of ground motion.

Past records of earthquakes to a large extent illustrate the

presence of a correlation between SI value and damage to structures . We developed a prototype SI sensor jointly with the Production

Technology Research Institute of Tokyo University and are endeavoring to commercialize the product.

Ground liquefaction sensor

This sensor detects a rise in the water level in sand layers as a

result of ground liquefaction. This is detected by changes to the

waterhead flowing into underground pipelines.

344
High-pressure line (natural gas trunk line) (P ^ lOkg/cmM

Works (sends out medium pressure gas B)

Customers for air conditioning

of a building or a community

Commercial customers Domestic customers

Xl

Block valve- valves being controlled by telecommunications shut-up valves

for regional divisions in case ol earthquake or other calamities. Fig. 2 Gas Supply System

Medium pressure A line (10 > P g 3 kg/cmM

I District governor

} (medium pressure A)

Block valve Medium pressure 8 line (X^^H (3 > g 0^ kg/cm*

I District governor

I (medium pressure)

low pressure line (200-230mm|

345
f

stoppage of Production A

and supply )

* When an earthquake occurs of magnitude or greater (eqivalent to 1923's Great Kanto Earthquake),

if necessary gas production and

supply are suspended.

Headquarters

Emergency

shut-off valve

•Headquaners receives by telemeter and other communications

equipment the information necessary for the constant production and supply of gas At the time of emergencies such as earthquakes, headquaners dispatches directions relevant to the situation.

(^Shut-off ^

Automatic shutoff occurs when

the seismic sensor detects an earthquake of 30 kina or greater

Block

Area block valve Low-pressure

line

( Shuf-Off) *^*^"''°*' 's effected by remote control from the

\ J Headquaners Supply Center Fig. 3 Hazard Countermeasures System

Supply pipe^^(^

» When the seismic sensor

detects an eanhquake of 200gal gravity or greater automatic shut-off occurs (MY-SAFE)

Fig.4 Isolation Area of Medium-Pressure

Pipeline Network (K-block)

346
each regulator shut off independently if the observed SI-value exceeds 30cm/sec

affecting area of each regulator

Fig. 5 Isolation Area of Low-Pressure

Pipeline Network (L-block)

Fig. 6 Telecommunication Networks

347
OCCURRENCE OF EARTHQUAKE

SI, Amax Values by Radio Telemeter

Damage Estimation System by SI and Amax

Acceleration Records by Radio Telemeter

Hypocenter

Estimation System

Structural Damage

Estimation System

Rise of Water Level by Radio Telemeter

Liquefaction Estimation System

Estimated Damage

Phase I

Hypocenter and MagnitudeEvaluated Damage

to Struaures

Occurrence of

Liquefaction

Estimated Damage

Phase n

^Decision Analysis ^

GENERAL EVALUATION

Fig. 8 Flowchart for Damage Assessment and Decision Making in a Supply Block

348
DAMAGE INSPECTION SYSTEMS IMMEDIATELY AFTER A MAJOR EARTTIQUAKE

By Kazuhiko KAWASHIMA, Hideki SUGITA, and Takashi KANOH

Earthquake Engineering- Division, Earthquake Disaster Prevention Department,

Public Works Research Institute, Ministry of Construction

ABSTRACT

This paper introduces a part of a comprehensive 5 year research program

entitled "Development of Information Collecting and Processing Systems for

Disaster Mitigation" of the Ministry of Construction. Description is given to the

current problems for correcting damage information immediately after a destructive earthquake in urban area and basic requirements for developing a new system. Emphasis is placed for a proposed seismic damage information

systems. Damage inspection way with use of video camera from a helicopter is

also presented.

INTRODUCTION

When a destructive earthquake occurs, it is of significant importance to

immediately collect accurate information on the extent of damage in the area

affected by the earthquake. Road transportation is likely to be interrupted in

urban area such as Tokyo as a direct result of damage of not only

transportation facilities but buildings and lifeline facilities along the road.

Confusion caused by people in evacuation and automobiles left on road are

anticipated, and they would also cause considerable disruption of

transportation. It is required therefore to develop a new information collecting

and processing systems which will enable the extent of damage to be recognized

immediately after an earthquake for formulating the repair and restoration

strategy promptly.

A comprehensive 5 year research program entitled "Development of Information

Collecting and Processing Systems for Disaster Mitigation" was initiated in 1987

by the Ministry of Construction. Public Works Research Institute, Building

Research Institute and Geographical Survey Research Institute are involved in

the research. The objectives of this research project were to develop new

information collecting and processing systems, using advanced new technologies,

for various disasters such as earthquake, floods and debris flows. As shown in

Fig. 1, key items of the research development are :

a) Bird's eye information collecting systems from helicopter,

b) On-line information processing systems, and

c) Real-time digital mapping systems.

For this purpose, measuring and assessing technology of the damage degree of

349
COMMUNICATIONS SATELLITE

REGIONAL CONSTRUCTION

BUREAU

PORTABLE

RECORDING SYTEM

TO IC MEMORY CARD

Q u U O LJ v O OU /

3c /CONSTRUCTION OFFICE

OTHER ORGANIZATIONS

(METROPOLITAN POLICE

BOARD. FIRE DEFENCE

AGENCY. ETC)

Fig. 1 Information Collection and Processing Systems

structures using moving picture information detected from helicopter and new

media oriented high-grade disaster prediction methods as well as planning

systems for repair and restoration in the damaged area Is now under

development. To avoid distortion of information during transferring from

regional office to headquarters, it is aimed to adopt visual motion picture

systems.

This paper briefly describes a part of the comprehensive research program with

emphasis on damage information collecting and processing systems for road and

river facilities".

PROBLEMS OF CURI^ENT DAMAGE INFORMATION COLLECTING SYSTEMS

AND BASIC REQUIREMENTS FOR DEVELOPING NEW SYSTEMS

Although there were not destructive earthquakes which seriously hitted urban

area in the last 40 years in Japan, it has been repeatedly pointed out from the

experience of local seismic damage that information collection and dissemination

are the most important but difficult issues for central and regional governments

in charge of control of public facilities'^ . This was also pointed out at the

Loma Prieta, U.S.A., Earthquake in October 1989'*^^'. From the past experiences,

various obstacles for collecting damage information are anticipated^' The

most important one is unexpectedly long time required for collecting damage

information due to interruption of road and damage of information transferring

media such as telephone. Even if the telephone could survive an earthquake,

350
disruption of communication repeatedly happened due to concentration of call

to a specific region.

Inadequate accuracy of the collected information is the second problem.

Unconfirmed and sometimes uncorrect information are sent. Only a part of total

information arrives. It is difficult to know the accuracy and correctness.

Sometimes the same information arrives through different routes, and they are

misunderstood as different information. Confirmation of source of information is

very important. When a series of events occurred, information on subsequent

event sometimes arrives earlier than the information of the preceding event.

There were examples that this caused significant misunderstanding on what were

going on the events and the repair.

Because most of information is transferred by a voice and letters, correct

evaluation on the information is difficult. Distortion of information always

occurs. Therefore it is required to send information in a form of visible

information. Still picture and moving picture information are quite effective.

Basic requirements for solving the problems of the current damage information

collecting systems are:

(1) Prompt Information Collection

Collection of damage information in wide area has to be made at not only day

time but night. Because accuracy of the damage information required changes in

accordance with time following an earthquake, it is important to be able to

collect damage information with reasonable accuracy depending on the time after

an earthquake. Visible information through video camera is quite important.

(2) Delivery of Updated and Same Information for All Bodies Involved in Repair

and Restoration

Although quality of the information required depends on the task of individuals

involved in repair and restoration, it is essentially important that the same and

updated damage information is able to be delivered for all individuals from site

engineers to decision makers. The real-time damage information has to be

displayed in the form of not only letters but moving picture. Because it is

important for site engineers involved in inspection and emergency treatment to

know real-time progress of damage and repair in other area for which they are

not in charge of, the systems should have capability to display the damage

information of not only inside but outside of the controlled area.

(3) Data Processing Systems for Repair and Restoration

The data processing systems has to be capable to control all the damage

information in a system, and can be used from the first stage (immediately after

an earthquake) to third stage (stage of permanent repair and restoration)^^ It should also have a capability to execute various simulation for studying

restoration strategy.

351
PROPOSED SEISMIC DAMAGE INFORMATION SYSTEMS

For enabling the requirements presented in the preceding chapter, Seismic

Damage Information Systems is proposed for collecting and processing seismic

damage information for repair and restoration of road and river facilities. The

Seismic Damage Information Systems is to be operated at the Main Headquarters

for Disaster Countermeasures (Headquarters Office of the Ministry of

Construction), the Headquarters for Disaster Countermeasures (Headquarters

Office of Regional Construction Bureaus) and the Branch for Disaster

Countermeasures (Construction Offices).

Fig. 2 shows layout and role of three sub-sections of the Seismic Damage

Information Systems. At Damage Information Processing Room, all damage

information are collected from various sources such as ground patrol teams,

helicopter patrol teams, other organizations and public. From such every types

of information, important information required for repair and restoration of

road and river facilities are identified. Preliminary statistical analysis of the

damage are made. At Damage Survey Room, repair and restoration plan based on

the damage information compiled at the Damage Information Processing Room are

formulated. Communication and adjustment for restoration with related

organizations such as police, fire department and local governments have to be

made at this stage. At Damage Countermeasure Room, basic policy and strategy

for repair and restoration based on the information compiled at the Damage

Survey Room is decide.

Fig. 3 shows an image of the Damage Survey Room and the Damage Information

Processing Room which should be placed at the Headquarters Office of Regional

Construction Bureaus.

The Seismic Damage Information Systems is of four sub-systems for collecting,

transferring, processing and maintenance of the damage information. The outline

of the sub-systems are as follows.

(1) Seismic Damage Information Collecting Systems

Information on seismic damage detected by helicopter patrol teams and ground

patrol teams is collected and processed in this systems. The damage information

is of moving picture, still picture and letters. They have to be detected by

video camera, electric still camera and electric hand notes. The electric hand

notes are specially designed man-machine handy type personal computers for

exclusive use for recording seismic damage. When the electric notes are

operated by field engineers, they automatically display and ask important items

for identifying the damage situation such as location, size, type and degree of

damage. The data are stored on floppy disk, and they can be sent to host

computer at headquarters by cables or radio communication systems.

352
SEISMIC DAMAGE DETECTED FROM

HELICOPTER, AND AIRPLANE

REGIONAL CONSTRUCTION O BUREAU, AND CONSTRUCTION

OFFICE. POLICE AND FIRE OFFICES

(a) FLOW OF INFORMATION

(d) DAMAGE INFORMATION PROCESSING ROOM

Fig. 2 Damage Information Processing Room, Damage Survey Room and Damage

Countermeasure Room of Seismic Damage Information Systems

353
(a) DAMAGE SURVEY ROOM (REGIONAL CONSTRUCTION BUREAU)

(b) DAMAGE INFORMATION PROCESSING ROOM (REGIONAL CONSTRUCTION BUREAU)

Fig. 3 Image of Damage Information Processing Room and Damage Survey Room

(2) Data Transferring Systems

Fig. 4 shows an image of the Data Transferring Systems for transferring the

damage information between Head-quarters, Regional Construction Bureaus,

Regional Construction Offices, patrol helicopters and ground patrol teams. The

information to be covered by the systems includes;

a) moving picture motion detected by video camera on helicopter

b) moving picture motion by video camera of ground patrol team

c) still picture motion by still camera of ground patrol team

d) character and mapping data used in the Seismic Damage Information

Processing Systems

e) Data on earthquake and meteorology which are telemetered

g) Information through telephone and faximile

354
(ground RtTROL PARTIES) DAMAGE, COUNTERMEASURE AND

RESTORATION INFORMATION

TELEMETER ON RIVER, ROAD, DAM FACILITIES

^t6

METEOROLOGICAL INFORMATION

EARTHQUAKE

INFORMATION

TELEMETER ON RIVER, ROAD, 0AM FACILITIES

RADAR PLUVIOMETER

HEADQUARTERS

• REFERENCE OF INFORMATION USING HOST- COMPUTER IN REGIONAL CONSTRUCTION BUREAU

DATA INPUT

REGIONAL CONSTRUCTION BUREAU

• CONTROL OF INFORMATION FROM

CONSTRUCTION OFFICES

• CONTROL OF INFORMATION FROM

RELATED SYSTEMS

• DATA PROCESSING

• DATA ADVERTISEMENT TO WORK

STATIONS

WORK STATION

DISPLAY UNIT OF TELEMETER

INFORMATION

CONSTRUCTION OFFICE

• DATA INPUT

• DATA TRANSMISSION TOWARD HOST- COMPUTER MAPPING DATA PROCESSING WORK STATION

MAPPING DATA DISPLAY UNIT OF TELEMETER

INFORMATION

CONSTRUCTION OFFICE

DATA INPUT

•DATA TRANSMISSION TOWARD HOST- COMPUTER

MAPPING DATA PROCESSING WORK STATION

MAPPING DATA

DISPLAY UNIT OF TELEMETER

INFORMATION

Fig. 4 Image of Data Transferring Systems

COMMUNICATIONS SATELLITE

DATA TRANSMITTING

DIVICE HELICOPTER /MOVING

PICTURE

RELATED ORGANIZATIONS REGIONAL CONSTRUCTION BUREAUS

STILL PICTURE, LETTERS, VOICE, FAX

COMMUNICATIONS

STATION

DATA TRANSMITTING/

ACCEPTING OIVICE

FROM

SATELLITE

FROM GROUND

J'JRFACE

COMMUNICATIONS

STATION

MOVING LETTERS STILL MOVING

PICTURE PICTURE PICTURE

FROM

SATELLITE

FROM GROUND

SURFACE

MOVING LETTERS STILL PICTURE PICTURE

STILL PICTURE, LETTERS, VOICE,

FAX GROUND PATROL PARTY

FROM

HELICOPTER

MOVING MOVING PICTURE PICTURE FROM HELICOPTER

DATA TRANSMITTING COMMUNICATIONS

ACCEPTING OIVICE STATION FROM GROUND FROM

SURFACE SATELLITE

STILL

' LETTERS

PICTURE MOVING

PICTURE

( headquarters) ( REGIONAL CONSTRUCTION BUREAU

)

(construction ofrce)

Fig. 5 Main Facilities for Data Transferring Systems

355
Main facilities required for the Data Transferring Systems are presented in Fig.

5. Main facilities Included in the systems are of satellite communication systems

and ground communication systems. The satellite communication systems includes

satellite, fixed receivers, portable receivers and moving picture transmitting

systems. The fixed receiver and portable receivers were already installed at

two and five of eight Regional Construction Bureaus, respectively. The ground

communication systems are of radio network for exclusive use of the Ministry of

Construction and picture motion communication systems. The radio network of the

Ministry of Construction covers about 800 locations including Regional

Construction Offices and local governments throughout the country.

HOST- COMPUTER

WORK STATION

SUB- SYSTEM FOR

DATA INPUT

SUB-SYSTEM FOR MAPPING DATA

SUB -SYSTEM FOR PRE-EARTHOUAKE

FACILITY INFORMATION

SUB-SYSTEM FOR EARTHQUAKE AND

METEOROLOGICAL INFORMATION

SUB -SYSTEM FOR

SEISMIC DAMAGE

SUB-SYSTEM FOR RESOURCES FOR

REPAIR AND RESTORATION

SUB-SYSTEM FOR COUNTERMEASURE

INFORMATION

SUB -SYSTEM FOR

REPAIR AND

RESTORATION INFORMATION

SUB-SYSTEM FOR SIMULATING

RESTORATION PROCESS

SUB-SYSTEM FOR COMMUNICATION AND ADVERTISEMENT

DATA INPUT FOR STRUCTURAL PROPERTIES, AND INFORMATION OF DAMAGE, REPAIR AND

RESTORATION. CONTROL OF MAPPING DATA, AND PLOT

OF DAMAGE, REPAIR AND RESTORATION INFORMATION CONTROL OF BASIC INFORMATION OF FACILITIES BEFORE EARTHQUAKE (INFORMATION ON ROAD NETWORK

RIVER, STRUCTURES AND MATERIALS IN STORE FOR DISASTER) CONTROL OF INFORMATION ON EARTHQUAKE AND METEOROLOGICAL

CONTROL AND REFERENCE OF SEISMIC DAMAGE INFORMATION

CONTROL OF INFORMATION ON

MATERIALS AND HUMAN RESOURCES FOR REPAIR AND RESTORATION

CONTROL OF INFORMATION ON WHAT WERE

DONE FOR COUNTERMEASURES

(EXCLUDING REPAIR AND RESTORATION WORKS)

CONTROL OF INFORMATION ON

REPAIR AND RESTORATION WORKS

SIMULATION ON REPAIR AND RESTORATION PROCESS

CONTROL OF INFORMATION ON TREATMENT AND

COMMUNICATION BETWEEN RELATED

ORGANIZATIONS, AND ON

ADVERTISEMENT FOR MASS-MEDIA

Fig. 6 Sub-systems of Seismic Damage Information Processing Systems

356
(3) Seismic Damage Information Processing Systems

Fig. 6 shows ten sub-systems for operating the Seismic Damage Information

Processing Systems. Whole seismic damage data, repair and restoration data,

mapping information, and facilities information prior to an earthquake are

compiled and controlled in this systems. Simulation of restoration strategy can

be made for clarifying the most appropriate way of restoration. Control of

information on adjustment with other organizations are made. Notice and

advertisement of damage situation and repair to mass-media is also controlled by

this systems. It is of host computer for data processing and work-stations for

data input and output. Analyzed data should be displayed on monitor in a well

organized form for deciding repair and restoration strategy.

(4) Audio Visible Systems

Fig. 7 shows an image of the Audio Visible systems. It includes screens with 200

inches and 70 inches, monitor of telemeters, projectors and electric black

boards. The Audio Visible Systems should have the capability to monitor the

damaged area through large screen, to understand the damage feature by

comparing the still and moving pictures taken prior to the earthquake, and to

conduct TV conference.

INFORMiTION FROM RELATED ORGANIZATIONS

MOVING PICTURE FROM REGIONAL

CONSTRUCTION BUREAU

HEADQUARTERS

MOVING /STILL

PICTURE FROM

CONSTRUCTION OFFICE

MOVING PICTURE FROM HELICOPTER

LARGE-SIZED. SCREEN

(I20-2OONCH) DAMAGE SURVEYING ROOM

MEDIUM- SIZED SCREEN DAMAGE (70 INCH) COUNTERMEASURE ROOMI

REGIONAL CONSTRUCTION

BUREAU

MOVING/STILL

PICTURE FROM

CONSTRUCTION OFFICE

URGE-SIZED

SCREEN

(I20-200INCH) DAMAGE SURVEYING ROOM

MEDIUM-SIZED SCREEN DAMAGE (70INCH) COUNTERMEASURE ROOM

MOVING /STILL PICTURE FROM

GROUIND PATROL PARTIES

MOVING PICTURE FROM REGIONAL

CONSTRUCTION BUREAU

CONSTRUCTION

OFFICE

DAMAGE INFORMATION PROCESSING ROOM/DAMAGE SURVEYING ROOM

AV \ j SWITCH ^

'

Fig. 7 Image of Audio Visible Systems

357
DAMAGE INSPECTION FROM HELICOPTER

Damage inspection from helicopter seems attractive to collect damage

information promptly because it is not interrupted by traffic congestion and

road suspension. To investigate tlie effectiveness of the damage survey from

helicopter, model damages were intentionally placed on various road and river

facilities. A helicopter owned by the Ministry of Construction was used for this

test. It is for exclusive use for disaster prevention as shown in Photo 1.

Photo 1 Helicopter for Disaster Prevention Owned by Ministry of Construction

A video camera which is set in a specially designed camera case for isolating the

camera from vibration of the helicopter was used to detect artificial damage.

The focal distance of the video camera is from 12.5 mm to 550 mm. By using the

focal distance of 550 mm, a flame of 4.8 m by 3.6 m can be recorded when the

height of the helicopter is 300 m which is regulated minimum height at city area. Real time transferring of the picture from the helicopter to the ground receiver

can be made. A thermal image sensor is also provided on the helicopter. It can

detect the difference of temperature with the resolution of 0.25 degree in

Centigrade. Because zoom as large as 4 times is provided in the thermal image

sensor, a flame with 37 m by 21 m can be recorded.

Various seismic damage was intentionally developed on bridges, pavement, road

embankment and river structures. Photo 2 shows cracks which were made by

placing white vinyl tape with width of 5 cm for aiming to represent a damage

developed at mid-height of reinforced concrete pier and a damage of prestressed

concrete deck. The former damage is likely to be developed when reinforcing

bars are terminated at mid-height with inadequate anchoring length^' , and the

358
Photo 2 Cracks Placed on Mid-height Photo 3 Damage Detected by Video Camera

of Pier and Girder Placed on Helicopter (Height is 321 m. Focal

Distance is 550 mm)

Photo 4 Bridges Detected by Thermal Image Sensor at Night (Height is 338 m)

359
latter damage tends to be developed on the concrete near the bearing

supports"' when the deck is pulled laterally. Photo 3 shows how such damages

are detected from helicopter flying 321 m above the ground surface with

velocity of 60 km/h^' . The focal distance was 550 mm. It is apparent that the

cracks at pier and deck can be clearly detected. The test was made by varying

the velocity and height of flight.

Photo 4 shows picture representing a new bridge construction along an existing

bridge in use for traffic. This was detected by the thermal image sensor at

night. Flight height was 338 m from the ground surface. Automobiles driving on

the existing bridge and four girders under construction can be apparently

seen"^^ . The thermal image sensor is effective to detect large damage of steel and

concrete structures.

Photo 6 Repair Work Detected

Photo 5 Slope Failure at Nashimoto District yideo Camera from Helicopter

of Izu Peninsula Detected by Video

Camera from Helicopter

Photos 5 and 6 show the seismic damage of road along natural slope , which was

caused by the Izu Ohshima-kinkai Earthquake'"" with the Richter magnitude of 7.0

in January 1978. Extensive slope failure was developed along the road with total

distance of about 125 m and height of 30 to 50 m , and this embedded a public bus

with three being killed. Photo 6 shows the repairing job by a crane. Because

this is a part of video taken by a TV company for broadcasting, the flight

information such as height and velocity is unknown. By carefully examining the

video record, length, depth and soil volume were surveyed by three geologists

with different professional careers"'. The geologist with 17, 10 and 5 years

professional career is designated herein as A, B and C geologist, respectively.

360
Table 1 Accuracy of Estimation by Three Geologists with Different Professional

Career

DAMAGE

GEOLOGISTS MEASURED

A B C AT SITE

AVERAGE WIDTH 70(CRANE(10m)x7) 60-80 10-30 lOOm

AVERAGE DEPTH 10(AVERAGE WIDTHx

1/7~1/10)

5-10 « 5m

FAILURE AREA * 320-480 *

SOIL VOLUME 20.000(30inx70mxl0m) 20.000 * 26,500

LENGTH OF ROAD

INTERRUPTED BY SLOPE FAILURE

100(AVERAGE WIDTH 80 * 125

1. MEANS THAT IT WAS UNABLE TO ESTIMATE FROM VIDEO TAPE

2. { ) REPRESENTS HOW GEOLOGISTS EVALUATED LENGTH, DEPTH AND DISTANCE

Table 1 compares the accuracy of the estimation by three geologists based on

the video film. It is interesting to note that the geologist A gives the most

appropriate estimation, and that the geologists with shorter professional

career tends to give 30 to 50 % smaller estimation. Because estimation was made

through video picture which is, of course, much smaller in size than the actual

damage, the surveyors tend to give smaller estimation in size.

Fig. 8 Geological Feature Detected by Geologist A based on Video Film

Fig. 8 shows the geological feature detected by the geologist A based on the

video film. Various information which is useful to judge the cause of failure and

probability to cause further progress of the failure can be obtained if the

video picture is carefully evaluated by a person with enough professional

knowledge.

361
It was found from the study that estimation of the volume and length of failure

is easier when artificial goods and facilities such as car, gird rails, house are

found in the moving picture because they can be used as a reference to measure

the distance On the other hand, it was found difficult to estimate the

distance and length when the failure is enormously large as compared with the

size of such artificial goods and facilities.

The study presented here is now being extended for studying the maximum flight

velocity to detect a certain size of damage'", effect of temperature and wind

velocity for detecting damage by thermal image sensor'^', and the most

appropriate way of flight

CONCLUDING REMARKS

When the Kanto Earthquake which resulted in about 120 thousands of death

occurred in September 1923, there were only about 4,500 vehicles in Tokyo City.

People evacuated by either walking or bicycle. This clearly indicates the great

difference of anticipated damage situation, between in 1923 and current time, in

urban area hitted by a destructive earthquake. It is important to note that

there have not be destructive earthquakes which hitted badly urban areas in the

last 40 years, and during this time the size, structures of living, lifelines and

techniques completely changed. It is therefore anticipated to face a new

situation when a large event happens near urban area. It is quite important to

develop and introduce a new systems for collecting and processing seismic

damage information.

FUTURE DIRECTIONS

Because the proposed systems would become a large systems consisting of a number of hardwares and softwares, further study has to be made for an

integrated architecture so that they are capable to be used even after a destructive earthquake. Special training for operating the systems is inevitably

important. Because sudden operation immediately after an earthquake can not be

made, it has to be used as a part of the comprehensive systems for daily use. Appropriate form of the emergency operation systems in normal time has to be

well examined.

Although the thermal image sensors are effective to detect large damage at

night, they can be used for surveying more detailed damage if the camera with

longer focus distance was developed. The use of new technology such as the high

vision camera is promising.

ACKNOWLEDGEMENTS

In executing the project, the Technical Research Center for National Land

362
Development established the Committee for the Development of Disaster

Information Systems, which is chaired by Dr. H. Umemiira, Professor Emeritus of

the University of Tokyo, with the commitment of the Ministry of Construction.

The reports presented in this paper are being executed with the supervision by

the Subcommittee for the Development of Supporting Systems for Disaster

Restoration Plan (Chairman : Professor Emeritus K. Kubo) and the Working Group

for the Development of Supporting Systems for Seismic Disaster Restoration Plan

(Chairman : Professor E. Kuribayashi) . The authors express their sincere thanks

to all committees members for their invaluable suggestions and guidance. Special

thanks go to Prof. T. Katayama, University of Tokyo and Prof. H. Kameda

University of Kyoto, for their invaluable suggestions. Final accomplishments of

the project are to be complied in March 1992 in the form of guidelines.

REFERENCES

1) Committee for Development of Disaster Information Systems : Report on

Development of Disaster Information Systems, March 1987, March 1989, March 1990,

March 1991, Technical Research Center for National Land Development.

2) Public Works Research Institute : Manuals for Repair Methods for Civil

Engineering Structures Damaged by Earthquakes, Technical Note of the Public

Works Research Institute, Vol. 45, December 1986 (in Japanese). Translated

version is published from the National Center for Earthquake Engineering

Research, University of New York, Buffalo, U.S.A.

3) Japan Road Association : Guide Specifications for Earthquake Hazard

Mitigation for Transportation Facilities - Repair and Restoration - , February

1987

4) Katayama, T. and Eisner, R. : What were the Lessons of the 1989 Loma Prieta ?, Bulletin of Earthquake Research Institute, University of Tokyo, No. 24, 1991

5) Kameda, H. , Asaoka, K., Scawthorn, C. and Khater, M. : Effects of the 1989 Loma

Prieta Earthquake on the Bat Area Transportation Systems, Proc. 8th Japan

Earthquake Engineering Symposium, Vol. 2, Tokyo, Japan, December 1990

6) Kawashima, K. , Unjoh, S. and lida, H. : U.S. -Japan Workshop on Seismic

Retrofit of Bridges, Public Works Research Institute, Tsukuba, Japan, December

1990

7) For example, Kawashima, K. and Nishikawa, K. : Earthquake Damage to Bearing

Supports of Highway Bridges Caused by the Miyagi-ken-oki Earthquake, Civil

Engineering Journal, Vol. 22-10, October 1980

8) Kawashima, K. , Unjoh, S., Sugita, H., Kanoh, T. and lida, H. : Survey on Seismic

Damage from Helicopter, Civil Engineering Journal, Vol. 32-1, January 1990

9) Public Works Research Institute: Report on the Disaster Caused by the

Izu-ohshima-kinkai Earthquake, Report of the Public Works Research Institute,

Vol.158, March 1982

10) Kawashima, K., Sugita, H. and Kanoh, T. : Survey of Seismic Damage by Video

Tapes Taken from Helicopter, Civil Engineering Journal, Vol. 33-1, January 1991

11) Kawashima, K., Sugita, H. and Kanoh, T. : Maximum Flight Velocity of

Helicopter for Surveying Seismic Damage With Use of Audio Visual Picture, Civil

363
Engineering Journal, Vol. 33-9, 1991

12) Kawashima, K., Sugita, H. , Kanoh, T. and lida, H. : Application of Thermal Image

Sensor for Survey of Seismic Damage, Civil Engineering Journal, Vol. 33-1,

January 1991

13) Kawashima, K., Sugita, H. and Kanoh, T. : Flight Method of Helicopter for

Surveying Damage Information Immediately After An Earthquake, Civil Engineering

Journal, Vol. 33-9, 1991

364
ESTIMATION OF DEGREE OF ANXIETY FELT BY PEOPLE

IN UNDERGROUND URBAN SPACES DURING EARTHQUAKES

By E. Saito, H. Ikemi, H. Nakano, and M. Nakamura

Dept.of Civil Engineering, Technical Research Institute, FUJITA CORPORATION

ABSTRACT

This study aims at discussing measures to be taken in underground urban spaces utilized by

I many people for disaster prevention during earthquakes. The objectives of this paper are; to identify a structural model of anxiety felt by people in the underground during earthquakes;

to extract major factors which will help to reduce people's anxiety; and to estimate the

degree of anxiety by the model through a survey on existing underground shopping malls.

(1)The most effective measures for reducing the degree of anxiety in underground spaces

during earthquakes include the training of guides, the construction of emergency facilities and

equipment, and training for disaster prevention.

(2)Comparison between new and old underground mall shows that the degree of anxiety regarding

to information about refuge, and to facilities and equipment for refuge have improved in new

underground mall. However, the degree of latent anxiety and anxiety regarding to leading

people to refuge have improved only slightly.

INTRODUCTION

The current social background including over-development and a rise in land prices in large

cities of Japan requires new spaces to be developed and utilized in order to maintain and

improve city functions. Recently, underground spaces have been spotlighted because they are considered to be appropriate to this purpose. The underground spaces must be artificially

closed. Hence, the underground spaces to be utilized by general people should be fully

examined legally, economically, technically, and from the standpoints of utilization and

disaster prevention. This study aims at discussing measures to be taken in underground urban

spaces utilized by many people for disaster prevention during earthquakes.

I As an example of existing underground spaces, shopping malls are amongst them. The first

i underground mall in Japan is "Subway Store" which was opened in 1932 in Kanda-Suda-Cho.

Existing large-scale underground malls were mostly built in the 1960s- 1980s. There have been

only a few disasters in underground spaces. Most of them were caused by fires. Although

earthquakes are frequent in Japan, no earthquake has ever caused a disaster in underground

spaces.

365
According to the questionnaire'^ which was conducted in 1990 on the count of 720 people,

people were most anxious about fire occurrences, then earthquakes, and finally other probable

accident related to underground malls. During an earthquake, they were anxious about

suffocation by smoke, an explosion caused by gas leak, people in a panic state who are pushing and shoving toward exits, and the collapse of malls. The other questionnaire^^ which

was conducted in 1978 on the count of 1,713 managers and employees of stores in underground

malls showed that about half of them were anxious of an attack by an earthquake while staying

underground.

As part of this study, brainstorming^^ on "Disaster Prevention Caused by Earthquakes in Underground

Urban Spaces" was carried out on the assumption that anunderground structure was attacked by an

earthquake. Results of this brainstorming are; the basic points of prevention of disasters caused by an earthquake which are to protect people and to reduce people's anxiety. These points include providing

emergency equipment, protecting underground facilities, furnishing adequate informations, realizing

the similar environment as that above the ground, giving disaster drills, training ag'ainst disasters, and

making the best use of underground environment.

The objectives of this paper are; to identify a structural model of anxiety felt by people in

the underground during earthquakes; to extract main factors which will help to reduce

people's anxiety; and to estimate the degree of anxiety by the model through a survey on

existing underground shopping malls.

STRUCTURAL MODEL FOR ANXIETY

Procedures for making the structural model are as follows:

Extracting factors of the proposition "Anxiety during Earthquakes".

Evaluating the relation between the factors through a questionnaire.

Identifying an objective structural model by the FSM (Fuzzy Structural Modeling) method''^ The

FSM method, an extended version of the ISM(Interpretative Structural Modeling) method^^ can

consider fuzziness related to correlation of the factors.

Factors of Anxiety

A. Factors of latent anxiety

B. Factors related to damages (direct and indirect damages)

C. Factors related to information about refuge

D. Factors related to leading of people to refuge

E. Factors related to facilities and equipment for refuge

F. Factors related to actions to be taken during an earthquake (action by the general public

in the underground spaces)

366
Based on the results of the brainstorming carried out as part of this study, these above

major factors for people's anxiety during earthquakes are classified with reference to causes

for a panic during a disaster^\ causes for a panic in underground malls^\ and an analysis

of behavior in houses*\ Subordinate factors for each major factor are shown in Table 1. The

structural model is made on the assumption that major factors are independent from each other.

1 Evaluation Between Factors and Structuring

Pairwish relations between every major factor and its subordinate factors are determined by

questionnaire. Then the questionnaire must include a total of 1,002 questions. Answers for

the questions range from 0.0 to 1.0 so that fuzziness is taken into account in structural

modeling. The number of examinees was sixteen: nine men including seven civil engineers and

two students specializing in civil engineering and seven women including five office workers

and two housewives. Because answers were expected to be different between men and women,

answers were classified into three groups; men's, women's, and all examinees. Then each group

answers' average were taken. Based on these averages, a binomial matrix (a fuzzy dependent

I matrix which is equivalent to an adjacent matrix by the ISM method) was determined. The

parameters p and A for the FSM method described in the next section refer to the threshold

and fuzzy structural parameter respectively. Unless otherwise specified, they are set as

j follows; p=0.5 and A =-0.3.

j Structural Model

I Structural Model for Major Factors

The highest hierarchy in Figure 1 is the proposed structural model. It apparently shows that

the proposition, "Anxiety during Earthquakes", is very closely connected to "factors of

latent anxiety" and "factors related to damages". Moderately connected are the "factors

I related to information about refuge", "factors related to leading of people to refuge", and "

I factors related to facilities and equipment for refuge". The "factors related to actions to

I be taken during earthquakes" is slighdy connected.

II Structural Model for Latent Anxiety

In calculation by the FSM, thresholds to which the asymmetrical law applies are set as follows for the three groups of men, women, and all examinees respectively; p=0.67, p=0.82

i and p=0.77. The higher threshold for the women group shows that women consider relations

I between factors to be strong although the causal relations between them are not clear. The

I hierarchy of factors of latent anxiety in Figure 1 is the basic structural model which was

! established by using the FSM method after examining the adequacy of this structural model.

' Factors of latent anxiety are resulting directly from the "unfavorable impression in the

underground"(l). More specifically, the causes are "sounds echo"(5), "lack of the sense of

367
time"(6), and it is "difficult to escape"(9). The degree of their relations shows that being

" difficult to escape" is the strongest cause for the "unfavorable impression in the

underground". The "unfamiliar space"(2), "closed space"(3), "difficulty to rescue people under

the ground"(4), and "artificial space"(7) are factors in the lowest hierarchy. Therefore,

latent anxiety can be reduced most effectively by providing measures for these factors.

Structural Model Related to Damages (in Figure 1)

Just like factors of latent anxiety, the threshold is higher for women than men. The

"recognition of damages"(ll) is the factor in the highest hierarchy. Factors in the

intermediate hierarchy can be divided into three blocks. The first block includes damages

which people recognize, the second block includes indirect damages of underground facilities

caused by an earthquake, and the third block includes direct damages. Factors in the lowest

hierarchy are factors of insufficiency whose counter measures for earthquakes are in regard

to underground facilities and equipment, fires caused by an earthquake, and prevention of the

expansion of damages due to the fact that underground space is an artificial space which

easily becomes a closed space. Therefore, providing measures for these factors in lowest

hierarchy is the most effective measures to prevent people from recognizing damages.

Structural Model Related to Information about Refuge (in Figure 1)

Just like factors of latent anxiety, the threshold is higher for women group than men.

The "inadequate information about refuge"(36) is resulting directly from "information

transmitted by word of mouth"(37) and "low reliability of information about refuge"(39).

Causes of "information transmitted by word of mouth" are "impossible to confirm information

about refuge"(38), "delayed transmission of information about refuge"(40), and "lack of unity

of information about refuge"(42). Causes of "low reliability of information about refuge" are "delayed transmission of information about refuge", "lack of unity of information about

refuge", "impossible to confirm information about refuge", "shortage of transmitted

information about refuge"(43), and "misunderstanding and insufficient confirmation of

information about damages" (46). To avoid inadequate information about refuge, providing measures for factors in the lowest hierarchy is the most effective measures. Factors in the

lowest hierarchy are: "impossible to confirm information about refuge", "operators of

underground stores are not well trained"(47), "means to transmit information is not

sufficient"(41), "shortage of means to gather information"(45), and "the centralized

monitoring system is not sufficient"(48).

Structural Model Related to Leading of People to Refuge (in Figure 1)

Experiments and instances shows that even when people apparently know the route to escape, the

degree of confusion is different according to whether there is someone or some announcements

to lead people to refuge. For these models, there are few differences in between men and

women. According to this model, the fact that "the guides do not know sufficient information

368
or the information is inconsistent"(52) and "the guide is not well trained"(53) lead to "the

shortage of guides"(54), which means one guide must leads more than the adequate number of

people to refuge. As a result, "the guides become upset"(50) and "the guides' instructions

become unclear"(49). Moreover, the guides "hurry people"(51), resulting in "inadequate

guidance" (55). The key to minimize the inadequate guidance is to provide adequate measures for

factors in the lowest hierarchy which are: "the guide does not know sufficient information

or the information is inconsistent" and "the guides are not well trained".

Structural Model Related to Facilities and Equipment for Refuge (in Figure 1)

Due to the shortage of facilities and equipment for refuge, it takes a longer time to escape,

resulting in greater anxiety. The most effective measures for this problem is to provide

measures for factors in the lowest hierarchy: "the shortage of routes to refuge"(59), "the

shortage of the refuge"(61), "the narrowness of routes to refuges"(62), and "the shortage of

equipment to prevent damages"(64).

Structural Model Related to Actions to be Taken during Earthquakes (in Figure 1)

The structural model for all examinees (p=0.7) is adopted as the basic structural model for

these factors. According to this model, the "people have no experience in a disaster"(69)

which leads them to "make light of a disaster"(70). In this case ,the reason being that "they

do not have a disaster drill in facilities they attend"(68). Then, including the fact that

"they have not been trained against disasters"(66) lead to the result of "not knowing how to behave when an earthquake occurs"(65)

AHP INFERENCE MODEL

Figure 2 a) shows the basic structural model determined by the FSM method (p=0.5 and A =-0.3)

of the major factors. The proposition, "Anxiety during Earthquakes", is completely described

by the six major factors. On this assumption, the degree of connections between the

proposition and each major factor can be shown by the proportional scale. The AHP (Analytic

Hierarchy Process)'^ estimate the degree of overall importance (or weight) of the whole

hierarchy. The degree of importance of elements (or factors), the proportional scale, in

each level of hierarchy, with respect to an element of a next higher level is determined by

pairwish comparisons. In Figure 2 b), the degree of connections is transformed into the

degree of importance. This hierarchical model was adopted as the AHP inference model for the

first and second level. The AHP inference model for the third level or lower hierarchies were

also determined in the same way as the higher levels.

Figure 3 shows a hierarchical model for major factors of latent anxiety. Factors in the

lowest hierarchy act as higher level elements for input elements. In this model, the input

elements are from Ql to Q8. The degree of latent anxiety is inferred by choosing between two

369
options for each question. For example, based on the assumption that you are in a certain

underground space, Ql asks how much one feel annoyed by echoing sounds in closed space. You

answer how much you feel annoyed by choosing a number from 1 to 9 for intensity of importance.

The value which show how much one does not feel annoyed is the reciprocal value of intensity

of importance. Table 2 shows the definition of the values from 1 to 9. In each binomial matrix

of answers, the eigen values is calculated. The eigen vector of the maximum eigen value shows

the degree of importance. Table 3 shows the degree of importance for each value from 1 to 9

as an alternative answer.

FACTORS REDUCING ANXIETY EFFECTIVELY

Figure 4 shows the results of the sensitivity analysis by the AHP inference model. Procedures

for it are as follows:

( 1

) Enter 1 for all input elements.

(2) Enter 9 for one input element.

(3) Estimate the overall importance (weight), which is adopted as the sensitivity of the input

element chosen in procedure (2).

The factor which shows the highest sensitivity in each major factor is : "the lack of sense of time"(6) caused by "closed space" for factors of latent anxiety; "the shortage of

facilities and equipment for emergency"(32) for factors related to damages; "the centralized

monitoring system is not sufficient" for factors related to information about refuge; "the

guides are not well trained"(53) for factors related to leading of people to refuge; "the

shortage of equipment to prevent damages in routes to escape and refuges"(64) for factors

related to facilities and equipment for refuge; and "people have not been trained against

disasters"(66) for factors related to actions to be taken during earthquakes. Among these, the

factor with the highest sensitivity is "the guide is not well trained" for factors related to leading of people to refuge, followed by "the shortage of facilities and equipment for

emergency" for factors related to damages and "people have not been trained against

disasters" for factors related to be taken during earthquakes. Therefore, providing

sufficient measures to train guides, furnishing facilities and equipment for emergency and

training the general public will help to reduce anxiety felt by people during earthquakes.

ESTIMATION OF DEGREE OF ANXIETY EXISTING IN UNDERGROUND MALLS

Using the AHP inference model, we have estimated how much anxiety people feel about existing

underground malls during earthquakes. In the AHP inference model, values for input were

collected through questionnaires.

370
Questionnaire

A questionnaire consists of 28 questions for all input elements for the inference model. To

verify the results of the inference, a question to the proposition about anxiety during

earthquakes was added. The questionnaire was attached with criteria for underground malls and

related data for reference. In the questionnaire, examinees answered the questions after

seeing a simulation film. Two underground malls which were built in the 1950s and after 1985

respectively were used in the simulation film. Therefore, the examinees answers were in

regard to the new and old underground mall. The number of examinees was twenty one, of which

fifteen were men and six were women. The breakdown of the men examinees are: ten civil

engineers, four university students and an elementary school student. The breakdown of the

women examinees are: two office workers, three housewives, and an elementary school student.

The questionnaire was based on the assumption that the examinees were hit by the Kanto

Earthquake while staying in the underground mall.

Estimated Results

Figure 5 shows the frequency distribution for the estimated degree of anxiety related to each

major factor. The ordinate represents the frequency and the abscissa the degree of anxiety

which is shown in Table 4. For the old underground mall, the sections from "almost yes" to "absolutely yes" showed higher frequency for each major factor excluding factors related to action to be taken during earthquakes. In contrast, for the new underground mall, the

sections from "rather no" to "rather yes" showed higher frequency. Therefore, we predict that

anxiety related to each major factor excluding factors related to action to be taken during

earthquakes in regard to old underground malls are stronger than new underground malls. Since

questions for factors related to actions to be taken during earthquakes ask about experiences

of an earthquake and a disaster drill, answers should be the same between old and new malls.

Therefore, differences between them may be attributed to the examinees' vague memories. The

frequency distributions spread more widely for the new underground mall than the old

underground mall. In particular, factors related to leading of people to refuge and factors

related to facilities and equipment for refuge showed wide frequency distributions. This may

show that although elaborate disaster measures are expected to be taken for new underground

malls compared to old ones, public estimation of these new measures is diversified.

Figure 6 shows frequency distributions for the estimated degree of anxiety and results of the

questionnaire which show the degree of anxiety during earthquakes while staying in the old

and new underground mall. Both the estimates and the questionnaire results show that anxiety

is weaker for the new underground mall than the old ones. However, the results of the

estimates and the questionnaire did not fully coincide with each other.

371
Figure 7 shows the average values of anxiety related to each major factor and anxiety during

earthquakes. Characters from A to F correspond to the major factors. "G" in the figure means

values of estimated degree of anxiety during earthquakes and "H" means the values of results

from asking about the degree of anxiety during earthquakes.

Figure 7 a) shows that there are big differences between the new and old underground mall

regarding to factors related to damages and factors related to facilities and equipment for

refuge. In view of this, we predict that these factors for the new underground mall will

thought to have greatly improved. However, it is obvious that factors of latent anxiety and

factors related to leading of people to refuge have improved only slightly. Moreover, the

results of the questionnaire and the estimates coincide fairly well with each other. The

figure also shows that anxiety regarding to the new underground mall is weak compared to the

old underground mall in the sections from "yes" to"cannot say".

Figure 7 b) shows that there are big differences between the new and old underground mall

regarding to factors related to damages and factors related to facilities and equipment for

refuge. In view of this, we predict that for the new underground mall will thought to have

greatly improved. However, it is obvious that factors of latent anxiety and factors related to leading of people to refuge have improved only slightly. In particular,improvements in

factors related to leading of people to refuge have increased only a small amount. Moreover,

the results of the questionnaire and the estimates of the proposition coincide fairly well

with each other. The figure also shows that anxiety regarding to the new underground mall is weak compared to the old underground mall in the sections from "rather yes" to "cannot say".

The samples' average value for the degree of anxiety related to major factors is higher for

women than men. The value for the proposition, "Anxiety during Earthquakes", shows the same

trend between men and women.

CONCLUSIONS

Conclusions of the study are as follows:

(1) The results of the sensitivity analysis tell that the most effective measures for

reducing the degree of anxiety in underground urban spaces during earthquakes include the

training of guides, the construction of emergency facilities and equipment, and training

for disaster prevention.

(2) Comparison between the new and old underground mall shows that the degree of anxiety

regarding to factors related to information about refuge, and factors related to facilities

and equipment for refuge have improved in the new underground mall. However, the degree of

anxiety regarding to factors of latent anxiety, and factors related to leading of people to refuge have improved only slightly. This trend is more apparent for women than men.

(3) Women examinees have stronger anxiety in underground malls during earthquakes and also

feel more anxious about major factors causing the anxiety in underground malls than men

examinees do.

372
(4) The samples' average of the questionnaire carried out in the new and old underground mall

on the degree of anxiety show nearly the same tendency as those of estimation by the

structural model. This indicated that the structural model can be considered to be almost

appropriate.

FUTURE DIRECTIONS

We will continue the survey by questionnaire so as to gain more reliable data. We will also

examine measures to reduce anxiety during earthquakes in view of the results of the survey

so far. Main items of measures are as follows.

1) Reducing the degree of latent anxiety.

2) Training method to guides and people.

3) Making new emergency facilities and equipment for disaster prevention.

We would like to continue collaboration between present researchers and with other related fields in

this study.

ACKNOWLEDGMENTS

This study was conducted as a part of study on "A Cooperative Research in Development of

Seismic Design of Underground Structures" in "Technology Research and Development Regarding

Use of Underground Space"of "A Comprehensive Research Project". The writers thank cooperative

researchers.

REFERENCES

1) Osamu Hiroi: Great Earthquakes and Underground malls, Monthly Fire Services Journal, 1990.

2) Tokyo Fire Defense Agency and Fire Prevention Council: Report on Research on Actual

Conditions of Underground Malls, March 1979.

3) Development of Seismic Design of Underground Structures, Cooperative Research Report of

DWRI,No.29,1989.8.

II 4) Amagasa: Thesis on System Structure -Based on Fuzzy Logic-, Moriyama Shoten, March 1986.

5) A.P. Sage: Methodology for Large Scale Systems, McGrow-Hill Book Co., 1977.

6) Research Association of the Construction Industry: The Latest Handbook for Disaster

Prevention for buildings, 1983.

7) Catalog of Regional Data for Disaster Prevention, Volume for Regional Refuge, Foundation

of the Center of Fire-Fighting Science, March, 1987.

8) Kobayashi: Human Behavior in Buildings during Disasters and Construction Plans, Annual

Report by the Disaster Prevention Institute of the Kyoto University, No.32B-2, April 1989.

9) Saaty, T.L.: The analytic hierarchy process, McGrow-Hill, Book Co., 1980.

373
Table 1 Factors for Anxiety • FACTORS OF LATENT ANXIEH

1 .Unfavorable impression in the underground

2. Unfamiliar space (have never been in the space)

3 . Closed space 4 . Difficult to rescue people under the ground (far from over the ground)

5 . Sounds echo (noisy, cannot catch information)

6. Lack of the sense of time (difficult to tell what time is it)

7. Artificial space (power supply, ventilation and supply of oxygen may be cut off)

8. Lack of the sense of direction (position and direction, difficult to tell where you are)

9 . Difficult to escape (unable to escape)

10. Secondary disaster may occur. (Ex. a fire, filling smoke) • FACTORS RELATED TO DAMAGES

11. Recognition of damages 12. Feeling unusual heat 13. Eyes tearing from the gas

14. Having difficulty in breathing

15. Catching an unusual smell (smell of gas and something burning)

16. Hearing something to get damaged 17, Hearing a scream 18. Things fall

19. Things shake 20. The underground structure cracks. 21. A fire breaks out.

22. The underground space is filled with smoke. 23. Water Leaks.

24. The electric supply is cut off. 25. Hazardous gas is generated.

26. The underground space is closed.

27. Facilities and equipment to protect the underground environment are damaged.

28. Structures are not designed to absorb vibrations caused by earthquakes.

29. Shortage of facilities and equipment for fire extinguishing purposes

30. Things are not made sufficiently fire-proof.

31. Facilities and equipment are not sufficiently waterproof.

32. Shortage of emergency facilities and equipment

33. Facilities and equipment are not sufficiently of seismic design.

34. Fire is used 35. Walls crumble. • FACTORS RELATED TO INFORMATION ABOUT REFUGE

36. Inadequate information about refuge (people do not believe the information or listen to it) 37. Information transmitted by word of mouth (rumor etc.)

38. Impossible to confirm information about refuge (or the general public)

39. Low reliability of information about refuge

40. Delayed transmission of information about refuge

41. Means to transmit information is not sufficient. (communication media)

42. Lack of unity of information about refuge

43. Shortage of transmitted information about refuge

44. Impossible to confirm whether information has been transmitted (one-way transmission)

45. Shortage of means to gather information (by store operators)

46. Misunderstanding and insufficient confirmation of information about damages

47. Operators of underground stores are not well trained.

48. The centralized monitoring system is not sufficient. • FACTORS RELATED TO LEADING OF PEOPLE TO REFUSE (BY GUIDES)

49. The guides' instructions become unclear. (about route and refuge)

50. The guides become upset, (a panic may occur.) 51. The guides hurry people, (make people run)

52. The guides do not know sufficient information or the information is inconsistent.

53. The guides are not well trained.

54. The shortage of guides (one guide must lead more than the adequate number of people to refuge) • FACTORS RELATED TO FACILITIES AND EQUIPMENT FOR REFUGE

56. People cannot find routes to refuge easily. 57. People take a long time to escape.

58. Guides cannot find facilities and equipment to lead people for refuge easily.

59. The shortage of routes to refuge 60. Routes to refuge are complex.

61. The shortage of refuges 62. The narrowness of routes to refuge

63. There are no definite refuges. 64. The shortage of equipment to prevent damages • FACTORS RELATED TO ACTIONS TO BE TAKEN DURING EARTHQUAKES

65. People do not know how to behave during an earthquake

66. People have not been trained against disasters.

67. People do not know how to use emergency equipment.

68. People do not have a disaster drill in facilities they attend.

69. People have no experience in a disaster. 70. People tend to make light of a disaster.

71. People do not know where emergency equipment is.

374
Table 2 Intensity of Importance

Intensity of Definition Intensity of Definition

Importance Importance

1 Cannot say 9 Absolutely yes

3 Almost yes 2,4,6.8 Intermediate values

5 Yes between the two 7 Rather yes adjacent judgements

Note: The reciprocal value is used for the opposite meaning.

Table 3 Degree of Importance of Alternative Answer

Answer 1 2 3 4 5 6 7 8 9

Degree of Importance 0.50 0.57 0.75 0.80 0.83 0.86 0.88 0.89 0.90

Table 4 Degree of Anxiety

Scale Degree of Anxiety Definition

1 0.10-0.12 Absolutely no - Rather no 2 0.12-0.17 Rather no - No 3 0.17-0.25 No - Almost no 4 0.25-0.50 Almost no - Cannot say

5 0.50-0.75 Cannot say - Almost yes

6 0.75-0.83 Almost yes - Yes

7 0.83-0.88 Yes - Rather yes

8 0.88-0.90 Rather yes - Absolutely yes

375
376
Anxiety during earthquakes

a) Structural model by the FSM method

Anxiety during earthquakes

0.8 0.9 0.7 0.7 0.6 0.5

Major factor Major factor Major factor Major factor Major factor Major factor A B C D E F

0.19 0.21 0.17 0. 17 0.14 0.12

Major factor Major factor Major factor Major factor Major factor Major factor A B C D E F

b) Hierarchical model for the AHP

Figure 2 Hierarchical Model for Major Factors

1

0.26 0.26 0.48

0.5 0.5 0.8 0.2 0.24 0.24 0.24 0.28

Ql Q2 0.53

D : Dummy element

1-10 : Refer to Table 1

0.47

Q7 Q8 0.64 0.36

Q3 Q4 Q5 Q6

Figure 3 Hierarchical Model for Factors of Latent Anxiety

0. 56

4)o 0.55 c

(0 0.54

a

0.53 -

0. 52

0. 51

>O 0. 50

0.49

1

i

1'/, QQQQQQQ I QQQQQQQ

12 3 5 6 7 Q

4

9 101112131415

B

Q Q Q Q Q

1617181920

C

QIQQQQQIQQ

2123 Q Q

2224 D

2526272829 3031

Major Factors

Figure 4 Sensitivity in Each Major Factor

377
Old Underground Mall

i-in

2 3 4 5 6 7 Degree of Anxiety

2 3 4 5 6 7 Degree of Anxiety

2 3 4 5 6 7 Degree of Anxiety

2 3 4 5 6 7 Degree of Anxiety A. Major Factor of Latent Anxiety D. Major Factor Related to Leading of People to Refuge

1 2 3 4 5 6 7 Degree of Anxiety

2 3 4 5 6 7 Degree of Anxiety

2 3 4 5 6 7 Degree of Anxiety

2 3 4 5 6 7 Degree of Anxiety B . Major Factor Related to Damages Major Factor Related to Facilities and Equipment for Refuge

100

90

o 70 -

= 50t-

(I) 40 -

30

20

10 -

n

New Underground Mall

m 1 2 3 4 5 6 7 Degree of Anxiety C. Major Factor Related to Information about Refuge

2 3 4 5 6 7 Degree of Anxiety

2 3 4 5 6 7 Degree of Anxiety2 3 4 5 6 7 8 Degree of Anxiety F . Major Factor Related to Actions to be Taken during Earthquakes

Figure 5 The Frequency Distribution for Estimated Degree of Anxiety Related to Each Major Factor

378
100

90

80 o 70

3 50

(D 40

30

20

10

0

Old Underground Mall

'A

2 3 4 5 6 7 Degree of Anxiety

2 3 4 5 6 7 Degree of Anxiety

a) Estimate by The AHP

100

90 S 80 ^ 70 o

C 60 - 0

3 50

cr

0) 40

30

20

2 3 4 5 6 7 Degree of Anxiety

New Underground Mall

2 3 4 5 6 7 Degree of Anxiety

b) Questionnaire Results

Figure 6 The Frequency Distribution for Estimated Degree of Anxiety

0. 7

0. 6

0.

0. 4

0. 3 ^1

9.

C D E

Major Factors

a) Examinees

0. 9

g 0. 7 - <

g 0. 6

-

CD = 0. 4 h

o 0. 3

0. 2 H

0. 1

0

to

Men

C D E F

Major Factors

b) Examinees ( Women

I

r

-V

Figure 7 Samples' Averages of Degree of Anxiety

( ^ : Old Underground Mall, E3 : New Underground Mall)

379
I

I

1

.1 .
PA9146

Performance of Lifelines and

Emergency Response in Watsonville, CA

To Loma Prieta Earthquake

4th U.S. -Japan Workshop on Earthquake

Disaster Prevention for Lifeline Systems

Los Angeles, August 19-21, 1991

J. Isenberg

Weidlinger Associates

Los Altos, CA 94022

Abstract

Due to disruption of lifelines in the Loma Prieta earthquake, communities such as Watsonville, CA

suffered economic losses and their emergency response staffs were severely challenged to provide

essential public safety and health services. Watsonville is typical of many cities in that services are partly provided by municipal utilities (water, sanitary sewage) and partly by outside utilities (gas,

electricity, telecommunications). The most significant problem for Watsonville was failure of

electrical power. Until power was restored several days after the earthquake, the City depended

entirely on emergency generators to operate water and sanitary sewer systems, support hospital

services and operate emergency fuel pumps. The resources of the Watsonville Fire Dept. were

completely deployed; no additional emergency siuiations could have been met effectively.

The impact on pubhc safety and convenience resulting from damage to the water system was

minimized because damaged regions were quickly isolated. Watsonville Community Hospital was

able to provide uninterrupted medical care because community members volunteered to provide

water and fuel for emergency generators. Watsonville businesses suffered inconvenience due

especially to loss of electrical power. The major costs to businesses were due to physical damage,

cleanup and revenue lost due to suspended operations.

INTRODUCTION

Due to disruption of essential utility services, or lifelines, in the Loma Prieta earthquake,

communities such as Watsonville, CA suffered economic losses and their emergency response

staffs were severely challenged to provide essential public safety and health services. Under its Lifeline Systems Program, the National Center for Earthquake Engineering Research (NCEER)

has begun to study how a community provides essential services despite damage to lifeline systems

and die costs of restoring those services following the Loma Prieta earthquake. Watsonville,

located 15 miles southeast of the city of Santa Cruz, is situated in a valley near the Pajaro River,

most of the city is within 10 miles of the fault rupture. The size of Watsonville (6 sq. miles,

population 29,()00, $1.4 billion total assessed valuation of property) makes it feasible to consider

the whole machinery of utility and emergency services working in the aftermath of a damaging

earthquake.

381
Watsonville is typical of many cities in that services are partly provided by municipal utilities (water, sanitary sewage) and partly by outside utilities (gas, electricity, telecommunications). As

pointed out in Ref. 1, it is widely assumed that the costs of repairs will be borne by the Federal

Government in the case of public utilities; by local tax payers; and by adjustments in rate structure for private utilities whose repair costs are not covered by grants in aid. The actual experiences of

utilities serving Watsonville provide valuable insight into the merits of lifeline hazard mitigation

and emergency preparedness from the standpoints of sustaining public safety functions and of

minimizing costs.

The total cost of earthquake damage to property in Watsonville was about $60 million. The total cost of repairing earthquake damage to municipally-owned property was about $4 million. This is about $140 per person and about 0.29% of assessed valuation. Of this amount, about $2.5 million was reimbursed by outside agencies; the remaining $1.5 million will be financed by the City over

Fiscal Years 1989/90 and 1990/91. Though primarily a residential and commercial community,

Watsonville also has industry which relies on water and electric power for continued operation.

The costs of plant closure and lost produce may be considered together with costs of restoring

lifeline services in justifying expenditures for lifeline hazard mitigation and emergency

preparedness.

OVERVIEW: PROMPT DAMAGE AND EMERGENCY RESPONSE

The most significant problem for the Watsonville community was failure of electrical power

supplied by the Pacific Gas and Electric Co. (PG&E) from its Moss Landing substation located

about 8 miles south of the city. The substation sustained damage to its 500-kv and 230-kv

switchyards (Ref 2). Until power was restored several days after the earthquake, the City

depended entirely on emergency generators to operate water and sanitary sewer systems, support

hospital services and operate emergency fuel pumps. The resources of the Watsonville Fire Dept. were completely deployed; no additional emergency situations could have been met effectively.

City officials stated that their emergency response, while effective, could have been enhanced by

having more emergency generators available and by recognizing and accepting the willingness of

neighboring communities to provide emergency aid.

The impact on public safety and convenience resulting from damage to the water system was

minimized because damaged regions were quickly isolated by the use of valves and because

emergency generators were already in place to operate pumps. However, the topography of the

service area dictates a system that has large areas serviced by a single source. This caused large areas to be without service due to a single source failure. Repair operations were seriously

restricted because the regional emergency response plan did not provide for passage of water and

sewer maintenance vehicles and equipment. With stop signals not functioning, this became a

serious problem for the repair forces. The impact of damage to the sanitary sewer system was

mitigated because a private contractor with a portable generator operated the lift pumps until power

was restored. Watsonville Community Hospital was able to provide uninterrupted medical care. Only one of its two emergency generators was useable immediately after the earthquake, however,

and the emergency fuel reserve was inaccessible due to inability to operate the fuel pump;

community members volunteered to provide water and fuel. Watsonville businesses suffered

inconvenience due to loss of lifeline service, especially loss of electrical power. The major costs to businesses were due to physical damage, cleanup and revenue lost due to suspended operations;

loss of frozen inventory also contributed to economic losses.

382
GEOLOGY AND SEISMOLOGY

Zones of potential liquefaction in the Watsonville area are described in Dupre and Tinsley (Ref. 3).

Liquifaction-related ground failure occurred within about 150 feet of major water courses draining

the area around the Pajaro River, to the south of the City, and Corralitos Creek which passes

through a residential district near downtown Watsonville. Approximately 80% of the areas exhibiting such failures are also reported in Youd and Hoose (Ref. 4) as having failed in a similar

manner following the 1906 earthquake.

The Modified Mercalli Intensity of shaking in Watsonville due to the main Loma Prieta event has

been estimated at VIII-IX. California Division of Mines and Geology strong motion station No.

1615, which is located in the Pacific Bell telephone building in downtown Watsonville, recorded a peak horizontal acceleration of 0.39g and a duration of strong shaking of about 6-8 seconds (Ref.

5). . . COST OF PROMPT DAMAGE

The value of losses to municipal property in Watsonville has been estimated at $4 million. About

65% of costs of restoring property has been paid by or claimed from the Federal Emergency

Management Agency (FEMA) of the U.S. GovemmenL Although some tax collections, especially

sales taxes, are below the level of the preceding fiscal year, the City is able to meet its fiscal

commitments.

Interaction between FEMA and City officials following the earthquake sometimes left the City

without clear guidelines on what costs would be paid by the government. For example, application

to FEMA for funds to assess damage to the sanitary sewer collection system did not receive

consistent response. FEMA is going to assist in restoring damaged sewer lines based on a 25%

deductible on the repair of sewer line. In the first week following the earthquake, FEMA told the

City it would pay to have all lines inspected by video camera; however, in the second week FEMA

told the City to reduce the scope of the inspection; in the third week FEMA said if video showed

no damage, it would not pay for the inspection. A major reason for such confusion is the lack of

experience with local conditions on the part of FEMA representatives and with federal disaster

relief procedures on the pan of the City. Efforts to improve communications are in progress.

PERFORMANCE OF INDIVIDUAL LIFELINE COMPONENTS

Water System

The present system was built in the 1920's. There are nine pressure zones in the city, with

interconnections between eight of these. The 11,800 connections in the system supply water to approximately 45,0(X) persons. In the earthquake, damaged areas were isolated by manual valves, so that leaks downtown did not bleed the entire system. No structures were lost due to a lack of

water. Three mobile homes and one fixed dwelling were engulfed by the time fire trucks arrived;

according to the Watsonville Fire Department, they would have been lost under any circumstances.

However, if water had been available, adjacent buildings would have been less damaged.

Except for a few isolated areas, service was restored to all customers within 24 hours. Lack of

water was regarded as an inconvenience for customers, but without major impact. There was a period of a few days when water pressures were low enough to present the threat of

contamination. Residents were advised to use chlorine bleach and not to drink murky or dirty

water. Subsequent testing found no contamination.

383
Water Supply

Eleven wells supply the main needs of the system (approximately 85% of the pre -earthquake

capacity of 13,300 gpm or 19 mgd). All water supplies are chlorinated. Raw water supply, from

two watersheds, is obtained through steel transmission pipes, and purified in a slow sand filtration plant.

A chlorine leak in a 150 pound cylinder could have threatened nearby residents. Power failures

interrupted pumping at two small wells; however, these two small stations represented less than

1% of the system capacity. The remaining wells continued to pump using emergency generators.

Fuel tanks for these generators were too small, and a person was completely dedicated to refueling

them. The eanhquake cracked floors of the sedimentary basin in the slow sand filtration plant.

This damage to the plant (it is currentiy not operable) has reduced the total capacity by 15%.

Storage

One redwood, four concrete, and four steel tanks varying in capacity from 0.3 to 3.0 mg provide

total storage of 11.7 mg. A one million gallon steel tank (built 1971) buckled at the wall-roof

juncture, due to failure of a bracket. The water level transmitting device was broken also. There was a leak of the pilot line to the altitude valve. The tank did not leak, however.

Water Transmission/Distribution

Twenty five major breaks appeared immediately. There had been 56 main breaks as of January 31,

1990. The 2^ne 1 (downtown) system had breaks in 8"- 14" pipes. With the power outage and

the breaks, maintenance of pressurization was impossible, creating the potential for contamination

(water testing revealed no contamination). According to the Watsonville Fire Department, the

estimated flow capacity in the zone 1 area was completely inadequate (150 gpm) immediately

following the earthquake. There was no flow in the higher areas for several hours, due to the need

to close valves manually that interconnect parts of the system.

Storm Drain System

The storm drain system serves the entire City and surrounding tributary areas. This system

collects and transports stormwater originating within the five drainage basins in and around the

City. The stormwater is then discharged into downstream natural drainage channels. Stormwater

is typically conveyed by gravity flow in open channels and pipes ranging from 12 inch to 60 inch

diameter. This system also includes thirteen pump stations located along the Salsipuedes Creek

and Pajaro River to handle stormwater discharge during periods of high tailwater. To date there

have been 123 damage sites discovered. Two pumping stations were damaged The impact to residents of the city was minimal, generally due to the lack of rainfall at the time of the earthquake,

and immediately afterward.

Sanitary Sewer System

The sanitary sewer system serves the entire city and Pajaro Dunes, a total population of about

29,000. Average flow is about 8 mgd, with peak flow up to 13 mgd. Effluent is chlorinated and

discharged to Monterey Bay through a 36 inch concrete lined steel outfall. It is mainly a gravity

fed system, witii 9 or 10 lift stations (4 or 5 from Pajaro Dunes). The system is comprised mainly

of vitrified clay pipe, which was originally laid about 1900.

The earthquake did not immediately block sewer lines. Inspection of several sewers indicated

broken pipes, misalignment and grade changes. Soil liquefaction was a major cause. Due to loss

of power, sewage could not be lifted into the gravity part of the system. The City hired a private

384
firm to provide local pumping until power was restored. About 150 sewer repair spots have been

identified, primarily in the downtown area. The City considered installing inner liners, but the cost

was prohibitive. The land portion of the outfall from the treatment plant developed two leaks

where it crossed unstable soil in a low lying area. There were no serious interruptions of sewer

service due to the earthquake. Minor overflows occurred. Surface flow of sewage was confined

to the break in the outfall line described above.

Gas

The response by PG & E to damaged gas lines is described in Ref. (6).

Watsonville System

There were two major gas leaks due to the earthquake; the intersection of Beach and Brennan

streets, and on Hill Street near Tuttle Avenue. There were numerous smaller leaks, including the

building fires caused in pan by the building shearing the service line at the meter. The fire

department shut off the gas to some buildings. The fire department also supplied PG&E with a portable radio to allow faster communication of serious gas leaks.

Watsonville is in PG & E's Mission Trail Region. There were initially 29,000 customer outages in

the region (breakdown for Watsonville not available). Approximately 200 homes fell off their

foundations and severely damaged the gas lines, and the old cast-iron and steel low-pressure

system was shutdown because of widespread leakage (see also water department report on fires in

mobile homes).

Most of the downtown Watsonville gas system consisted of old steel pipes, varying in size from 2"

to 4" and in age from pre- 1930 to 1974. Ref (6) details damage to the main distribution pipes

(Exhibit 9 of repon). About 85% of the system has been replaced since the earthquake. New 2"

plastic pipes were either insened through the old pipes, whenever possible, or laid into new

trenches. The plastic pipes can take higher pressure (30 psig) but a regulator is needed at the

service connection to step the pressure down to the required 2-3 psig. According to a PG&E

spokesperson, most new pipes installed will be these high pressure plastic pipes.

Emergency Preparedness

PG&E has emergency preparedness plans which include an emergency operations center to coordinate all crews and actions in the aftermath of an earthquake. Details are given in Ref. (6).

Each region maintains a stockpile of emergency material, including pretested pipes. Several

regions and divisions have established plans for mutual aid within the region and from other

regions. PG&E recognizes the problem with fires, especially for mobile homes.

The distribution network is divided into emergency shutdown zones that are separated by valves.

Each zone can range up to 40,000 customers. PG&E would not consider shutting off a zone

unilaterally upon the start of an earthquake because:

1. It is difficult to tell which is the right zone to shut off; information from customers is not

reliable.

2. If a zone is shut off unnecessarily, customers would be inconvenienced or would need the fuel

for emergency puiposes.

3. The relighting process is very slow, labor-intensive and expensive.

385
PG&E has a Supervisory Control and Data Acquisition system (SCADA) which is used to monitor

the status of transmission and distribution facilities. An operator can shut off particular

transmission lines, but this is not an automatic post-earthquake procedure.

Communications

The City emergency communication center was not available due to loss of power. Officials relied on face-to-face communication at hourly intervals. They had a generator to run the emergency

communications, but the exhaust went into the AC system, so it was not useable. Radios in water

trucks were used until power was restored. The need for additional tactical frequencies was noted;

too many emergency crews for the number of bands available.

Roads, Bridges

The only road closures were the Struve Slough Bridge (Highway 1) and the Pajaro Bridge.

Following the earthquake, traffic was slowed due to debris in the streets from damaged and

collapsed buildings, gas leaks (above), lack of traffic lights due to a power outage, and from slow

"sightseers". Some roads in the heavily damaged areas were closed afterwards, for public safety.

Fire trucks were able to traverse all roads (except bridge closures); detours were made around

intersections with the gas leaks. The Watsonville Fire Department said that response times were

increased due to lack of accessibility. Due to lack of coordination in the emergency response plan,

some pipeline repair crews were not allowed into closed off areas to repair pipelines. Watsonville

will pay half the cost to replace Pajaro Bridge. This is not included in the $4 million estimate of

damage.

Emergency Response

Seventy percent of the Watsonville Dept. of Public Works staff reported for work. Resources of

the Watsonville Fire Department were completely deployed. One added emergency, such as another building collapse, would have been met with diminished resources. The Asst. Fire Chief

said that the Disaster Plan was effective and would not be substantially altered to meet future

emergencies. An exception is that the City mistakenly assumed that there would be no outside

help, so they never requested any. In fact there were significant resources available from

neighboring communities. Eventually, coordinating volunteer helpers became a burden.

Watsonville was the first city or among the first in California to complete a Hazard Mitigation and

Emergency Operations Plan; it was completed in 1985. Several City employees attended

California Special Training Institute Workshop on Disaster Preparedness conducted by the

California State Office of Emergency Services.

Medical Services—Watsonville Community Hospital

Watsonville Community Hospital provided essentially uninterrupted medical care for the

community after the earthquake. While medical care was available, service was affected by the

earthquake, at least for a number of days after the event. The need for modified medical service

resulted primarily from interruptions to hospital lifelines supplies. Key lifeline interruptions are highlighted below.

Electric Power

The hospital's electric power supply, provided by PG&E, was interrupted for several days

following the earthquake. Emergency power is provided by the hospital's two emergency

generators. During the Loma Prieta Earthquake, one of the generators "walked off of its foundation". The lack of adequate seismic anchorage of the generator rendered it unusable after the

386
earthquake. Among the elements served by the unusable generator were life support systems.

Fonunately during the time of the earthquake, no patients were dependent on life support systems.

In less than an hour after the earthquake, in-house maintenance engineers were able to transfer

demand from the unusable emergency generator to the operational one. Because each generator

was sized to accommodate one hundred percent of the hospital's emergency power demand, the

remaining functioning generator was capable of fulfilling all emergency power needs. Recovery

efforts were greatiy facilitated by the prompt response of in-house staff and by the reserve capacity

provided in each generator.

Difficulties arose in refueling the functioning emergency generator due to a broken fuel supply line. The reserve fuel supply, a 5000 gallon tank below grade, required an auxiliary system to bypass

the damaged supply line and fuel the generator. The hospital's portable pump was used to transfer

fuel from the underground storage tank to a 55 gallon drum which in turn was transferred to the

generator fuel tank. The fueling procedure was streamlined when a local corporation. Granite

Construction, provided the hospital with a fuel truck.

Communications

The primary communication problem faced by the hospital related to the difficulty in placing

outside calls. Because of the high demand placed on the phone system, outside calls were subject

to lengthy delays. The hospital's in-house phone system suffered some minor damage which

required reloading of their computer database. This operation was completed in less than an hour.

Water

A sprinkler line, which crosses between two structurally independent buildings without a flexible

connection, ruptured during the earthquake. Several additional steam and water pipes also broke.

Damaged portions of the piping systems were isolated by manually turning off flow valves.

Approximately 80 percent of the hospital was without water for some period of time as a result of

in-house damage. The city water supply was never lost entirely, but pressure was severely limited

at times.

Portable toilets were delivered to the hospital the day after the earthquake as a precautionary measure. Gallo Winery provided the hospital with supplemental drinking water the day after the

earthquake.

Sewage

Several sewer lines in the ground were broken during the earthquake. These breaks were not

immediately identified, however. After one month, a tremendous increase in the number of flies was observed. This prompted a video camera survey of the sewer lines to assess the nature and

scope of the problem. Where breaks occurred in underground piping within the hospital building,

new overfiead piping was installed to bypass the damaged pipes.

Additional

One leg on an upright liquid oxygen tank buckled during the earthquake. As a consequence, piped

oxygen was unavailable for medical use. Available portable oxygen tanks were sufficient to nneet

all patient demands until repairs to the piped oxygen system could be made.

Watsonville Businesses

Many Watsonville businesses suffered substantial losses as a result of structural damage,

nonstructural damage, and/or lifeline interruptions. The experiences of 5 businesses which

387
suffered little or no structural damage are highlighted below to provide some insight into the impact

of lifeline interruptions on business operations.

Based on interviews with 13 Watsonville companies, the continuity of lifelines was cited as a key

to sustained business operations and efficient recovery efforts. Power was most commonly

reponed to be the most vital lifeline for restoring business operations. While power outages did

slow recovery efforts in Watsonville substantially, the power interruptions alone did not appear to cause the majority of losses to the business community. This is in part because a large portion of

the local industry consists of cold storage facilities which are somewhat insulated from power

interruptions lasting only a few days. It takes on the order of a week or more to increase the

temperatures of stored goods sufficiendy to render them unfit for commercial distribution.

Del Mar

Del Mar is a medium-sized firm which packs and stores frozen foods. At the time of the

earthquake, the peach harvest had recendy concluded and their freezers were full of peaches.

Power was lost at Del Mar for approximately 2 days. Although the firm has no emergency source of power, the freezers maintained a sufficiendy low temperauire that no fruit was lost There was a small ammonia leak on the site which was handled by in-house maintenance crews. Total losses on the order of $150,000 were reponed.

Company 2 (Prefers To Remain Anonymous)

Company 2 is a large firm which packs and stores frozen foods and has facilities at many locations

including Watsonville. At the time of the earthquake, 40 million pounds of product were stored on

site. Power was lost at Company 2 for approximately 40 hours. This interruption of power did

not cause a significant rise in temperature of the stored goods and no inventory was lost as a result

of a lack of power. The biggest problem experienced by this company was that about half of their

stored products fell over. Recovery efforts consisted primarily of cleaning up the site, repackaging

goods where possible and disposing of goods as needed. Miscellaneous repairs to sprinkler piping were also needed. Emergency generators were brought to the site to facilitate clean up operations.

Company 2 estimates their losses at approximately $1 million - approximately $100,000 in

physical damage, approximately $450,000 in direct expenses incurred during the cleanup effort,

and the remaining $450,000 in lost revenue resulting from the diversion of business during the

company's one-month shutdown.

The Pillsbury/Green Giant Company

The Pillsbury/Green Giant Company was apparentiy most severely impacted of all cold-storage

facilities in Watsonville. According to Ref (2), moderate structural damage was suffered at the

facility. The structural damage did not, however, place the building in danger of collapse nor lead

to substantial operational interruptions. Substantial business interruptions resulted instead from

damage to "nonstructural" components.

Cold storage vaults at the facility are cooled via ceiling-mounted cooling coils which operate with

ammonia refrigerant. The ceiling-mounted coils were not braced laterally at the time of the

earthquake and hence, swayed under the seismic excitations. The attached refrigerant tubing was

not able to accommodate the relative movement of the coils and cracked or separated from the coils

at several locations. The City of Watsonville Fire Department, EPA and Hazardous Materials

Board were notified of the ammonia leak soon after the earthquake. The Watsonville Fire

Department arrived on site and assisted in venting the cold storage room affected by the leak and

conducting a survey to verify the extent of damage to the refrigerant tubing. Since the Loma Prieta

Earthquake, the Pillsbury/Green Giant Company has undertaken measures to minimize future

388
earthquake damage. Specifically, lateral bracing has been added to refrigerant lines and coils, and

isolation doors were installed to reduce the size of the storage area that could be exposed to a single

ammonia leakUndisclosed financial losses resulted from the need to discard the produce present in the 30,000

square foot cold storage area affected by the ammonia leak. The facility was able to resume partial

production approximately two weeks after the earthquake and was in fuU operation one month after the earthquake.

Due to the nature of damage at the Pillsbury/Green Giant facility, the interruption of some lifelines

serving the facility posed relatively minor inconveniences to recovery operations.

Monterey Savings

Banking operations at Monterey Savings, located in downtown Watsonville, were suspended for

approximately three days. The loss of operations was directiy dependent on the loss of commercial

power at the facility. Once power was restored, tiie bank was fully operational.

Skyway Freight Systems

Skyway Freight Systems is a transportation company providing air freight, truck and

transportation information services. Skyways corporate headquarters are located in Watsonville.

Approximately 120 are employed at the Watsonville facility. Commercial power was restored to Skyway approximately one week after the earthquake. To accommodate operations prior to power

restoration, an emergency generator was shipped from the company's Los Angeles facility. The

generator was delivered one day after the earthquake. It was fueled with gasoline pumped from the

company's trucks. The generator was used to supply power primarily for computer data

entry.Phone service was fully restored at Skyway about a week after the earthquake. During the

service interruption incoming calls were routed to Los Angeles and Chicago facilities.

Lingering Damage

There is evidence from previous U.S. earthquakes to suggest that seismic ground shaking

accelerates the normal process of aging in underground pipelines (Ref. 7). Ground shaking

loosens metal already weakened by corrosion and disturbs caulking already distressed by

settlement and traffic vibrations. The possibility that this will happen in Watsonville, as happened

in Coalinga after the 1983 earthquake, is a matter of concern because the extra cost of above

normal maintenance is an ongoing, earthquake-related cost that may not be compensated by outside sources. The City of Watsonville is currently examining the condition of its sanitary sewer system

with this consideration in mind.

Conclusions: Interaction Among Lifeline Components

The experience of Watsonville in die Loma Prieta Earthquake shows that the loss of electric power

degrades emergency response. In Watsonville, the availability of electric generators enabled the

City to make best use of its resources. This is most apparent in the water supply system, where

well pumps operated by emergency generators were able to meet the water demand everywhere

except in the downtown area, which was deliberately isolated to prevent multiple breaks from

degrading the rest of die system. Portable generators also were used by a private company to operate pumps at lift stations in the sanitary sewer system. The inability to use an emergency

generator in the town Emergency Communication Center made it necessary to use radios in

vehicles, which was unsatisfactory due to limited bandwidth. It was difficult to pump gasoline

from below-ground tanks into vehicles for transport to emergency generators. Among the few

things the City would do differentiy next time is to have more portable electric generators and more

389
convenient storage of fuel to operate thenL

Future Directions For Research, Applications And Design

A seismic risk study to consider interaction between lifelines, analogous to the one recently

completed by the Water and Sewage and Seismic Risk Committees of the ASCE Technical Council on Lifeline Eanhquake Engineering, should be developed. The goal should be to examine the

effects caused by failure of electric power on other lifelines, especially water and communications.

The first stage of the study should explore qualitative historical evidence of impacts, such as failure

of pump stations, of electric power failure. Research is needed to develop a theoretical and

computational framework to accommodate the uncertainties of two lifeline systems and the

connections between them.

References

1. Thiel. C. C. "Lifelines. Seismic Hazards and Public Policy" . Social and Economic Impact of Earthquakes on

Utility Lifelines . Seismic Considerations in Lifelines Planning, Siting and Design, ASCE Specialty Conference,

19-20 May 1980, San Francisco, Ca., ASCE, New York. NY, 1981.

2. Schiff, A and L. Lund, Coordinators "Loma Prieta Reconnaissance Report" Chapter 8, Lifelines, Eanhquake

Spectra, Supplement to Vol. 6, May, 1990.

3. Dupre, W. R. and J. C. Tinsley, "Geology and Liquefaction Potential Northern Monterey and So. Santa Cruz

Counties" . U.S.G.S Map 1199, U. S. Geological Survey, 1980.

4. Youd, T. L. and S. N. Hoose, " Historic Ground Failures in Northern California Triggered by Earthquakes" . Geological Survey Professional Paper 993, U. S. Geological Survey, 1978.

5. Shakal, A. et al "CSMIP Strong-Motion Records from the Santa Cruz Mountains fLoma PrietaV California

Earthquake of 17 October 1989" . Report No. OS MS 89-06 California Strong Motion Instrumentation Program,

California Department of Conservation, Division of Mines and Geology, November 17, 1989.

6. Phillips, S. H. and J. K. Virostek, "Natural Gas Disaster Planning and Recovery: The Loma Prieta Earthquake,"

Pacific Gas and Electric Co., San Francisco, April, 1990.

7. Isenberg, J., "Post-Earthquake Performance of Pipelines in Coalinga". Earthquake Spectra, Vol. 2, No. 4,

October, 1986.

Acknowledgements

This paper is based on a previous paper entitled "Watsonville Regional Study: Interaction Among Damaged

Lifelines" by J. Isenberg, M. T. Phipps and C. Scawthom which was presented at "Putting the Pieces Together"

Conference, Oct 15, 1990, Hyatt Regency Hotel, San Francisco Airport Each author contributed significantly to the preparation of the previous paper.

This work was supported by grants from the National Center for Eanhquake Engineering Research, Buffalo, NY.

The study was initially suggested by Masanobu Shinozuka, Technical Director of NCEER. The assistance of

members of the City of Watsonville Department of Public Works and Fire Department; staff members of PG&E;

and Watsonville Community Hospital are gratefully acknowledged. Data on geology and ground shaking in the Watsonville area were provided by staff members of U.S.G.S., Menlo Park, Ca. Significant contributions to the

collection of data used in this paper were made by Tom Larsen of EQE Engineering, Inc. and by Felix S. Wong of

Weidlinger Associates.

390
STRATEGIES FOR REPAIR AND RESTORATION OF

SEISMICALLY DAMAGED GAS PIPELINE SYSTEMS

M. Shinozuka

National Center for Earthquake Engineering Research

M. Murata

PASCO Corporation

T. Iwata

Tokyo Gas Co., Ltd.

391
INTRODUCTION

The purpose of this study is to develop a strategy for the repair of seismically damaged gas

networks. Based on the concept taken from a study by Isoyama et al. (1985), a series of

programs have been coded and a prototype computer systems developed. An important

characteristic of the computer systems is the implementation of GIS (Geographic Information System). GIS is a computer tool for acquisition, manipulation and retrieval of spatial

data. In this study, a commercial GIS package, ARC/INFO, available from Environmental

Systems Research Institute (ESRI), California, was used.

GAS PIPELINES

A city gas network usually consists of two types of networks; high or medium pressure lines

and low pressure lines. Figure 1 shows a model of the medium and low pressure lines. As

shown in the figure, the medium pressure network includes two types of nodes; sources and

regulators. Source nodes which include gas plants, send out medium pressure gas to the

network. Regulators on the medium pressure pipes from which the low pressure pipelines

originate control gas supply to the low pressure lines.

RESTORATION OF SEISMICALLY DAMAGED NETWORK

Restoration of a seismically damaged gas network involves two major steps. One is the

restoration of medium pressure lines, and the other is the restoration of low pressure ones. Before starting the restoration of low pressure lines, however, medium pressure lines must

be completely restored. In the study by Isoyama et al, the restoration work of medium

pressure lines is assumed to be performed pipeline by pipeline, while low pressure lines are assumed to be restored small district by district. This study primarily deals with the

restoration of medium pressure lines.

Figure 2 shows a flow chart that describes the procedures for determining the priority of

repair. A brief description is given below.

ARC/INFO Data Base

A hypothetical network on which the example analysis will be performed is created in the

form of a digital map or a so-called "coverage", according to the ARC/INFO terminology

(ESRI, 1989). Figure 3 shows the network coverage used in this study, which consists of 30

links and 27 nodes. Among the 27 nodes, two are source nodes, 13 are regulators and 12

392
are junctions. Each feature has attributes which are necessary for the determination of

repairing priority. These attributes are stored in the relational database, and can be

retrieved as properties of features. The information of the coverage is converted into text

files, and can be processed by other computer programs.

Link Data

Table 1 indicates the attributes of the links such as link ID number under the columns

identified by the numbers 06 through 10 (see the first two rows), starting and ending nodes

indicated by the numbers 11 through 15 and 16 through 20, respectively.

Node Data

In Table 2, the node attributes are shown in a similar fashion to Table 1.

Pipe Breaks in Medium Pressure (MP) Lines

Pipe breaks in MP lines are simulated using a Monte Carlo Simulation technique. First, the occurrence rate of pipe breaks (per unit length) is calculated as follows; For a given

Modified MercalH Intensity (MMI) = I which is assumed to be common over the entire area where the network is located.

C2(I-Cj)

ij = q-io (1)

where n is the occurrence rate for pipe j and Cj , C2 , and C3 are constants. These

constants are assumed to take values listed in Table 3, based on the pipe elements (Eguchi,

1984).

Second, assuming that the pipe breaks follow the Poisson law, the probability Pjj^ of exactly

k breaks occurring in pipe j, is computed as.

(rj-Lj)*

Pjk = exp (-rj'Lj)

k !

(2)

where, Lj is the pipe length (km).

393
Third, applying the standard Monte Carlo technique, the number of breaks in each pipe will

be simulated. In this Monte Carlo simulation, a random number x uniformly distributed

between 0 and 1 is generated and the number N of breaks is assumed to have occurred if N-l N ° E P|ij < X < E Pjjj . k=o J k=o

Pipe Breaks in Low Pressure (LP) Lines

The number of breaks in LP lines connected to regulator i is calculated as follows,

Dnj = r-Ltj (3)

where Ltj is the total pipe length of LP lines, and r is the occurrence rate calculated using

Eq. (1). The element type 4 (see Table 3) is assumed for all LP lines, which are assumed

to be made of cast iron.

Link Distance

Link distance Ldj of pipe j to be used in the shortest path analysis which will follow, is expressed as a function of the flow rate Qdj in pipe j, and of the factor which quantifies the

level of difficulty in repairing each break, referred to as the difficulty factor for repair tj. It

is defined as,

Ldj = p/Qdj + q-tj (4)

where p and q are coefficients to which the following values are assigned for numerical

purposes.

p = 10000, q = 100

394
The gas flow rate Qdj in the pipe is a function of the diameter d and length L of the pipe

as shown below.

Qdi = Y

5

(5)

where y is a constant. The difficulty factor of repair is calculated as,

t,i = a*U + b»DL (6)

where Dlj is the number of breaks in pipe j, "a" represents the efficiency of inspection

(day/km) and "b" represents the efficiency of repair (dayA^reak).

Node Weight

where Ncj is the number of customers serviced by the regulator, Dnj is the number of

breakage in LP lines connected to the node, and jS^ is a parameter which represents the

importance of the node.

Shortest Path

In this study, the restoration between either one of the sources and a node proceeds along

the shortest route between them to be determined based on link distances described above.

Node weight Nwj represents the importance and necessity of restoring the function at node

i. It is defined as

NcNWj = i3j- (7)

395
Link Weight

Link weight is determined by adding all the node weights associated with the shortest routes

which include the link under consideration. For example, link 1 in Fig, 4 is shared by two

shortest routes to node 3 and node 2, and hence the link weight is Nw3 + Nw2 .

Priority of Repair

For each seismic intensity, steps (4) - (9) as indicated in Fig. 2 are performed repeatedly for

all the trials of the simulation. After all trials are carried out, the resulting link weights are averaged and the repair priority is determined based on the averaged hnk weight. Figure

5 shows the histograms of link weight under seismic intensities VIII and IX. As shown in

these figures, links which are closer to source nodes have higher priority as expected. Also,

the priority order does not show any significant change as MMI scale increases.

In this study, seismic intensity was assumed to distribute identically over the entire network.

Since the service area of a gas network is generally wide-spread, the spatial distribution of

the ground motion intensity should be considered in future studies. Furthermore, the

method discussed here should be improved and modified for more reasonable modeling of

the restoration work on the network. These improvements should be implemented with

consultation with repair and restoration experts with gas utilities.

ACKNOWLEDGEMENT

This work was partially supported by Project # NCEER-903005 under NSF Grant ECE8607591. The support by Tokyo Gas Co., Ltd. and Pasco Corporation is also acknowledged.

396
REFERENCES

Eguchi, R.T., "Seismic Risk and Decision Analysis of Lifeline Systems", Lifeline Earthquake

Engineering: Performance, Design and Construction. Proceedings of a Symposium

Sponsored by the Technical Council on Lifeline Earthquake Engineering of the American

Society of Civil Engineers, ASCE, New York, NY, 1984.

Environmental Systems Research Institute, Inc., "ARC/INFO Users Manual", Redlands, CA,

1989.

Isoyama, R., Iwata, T. and Watanabe, T., "Optimization of Post-Earthquake Restoration of

City Gas Systems", Proceedings of the Trilateral Seminar-Workshop on Lifehne Earthquake

Engineering, National Taipei University, Taipei, Taiwan, 1985.

Iwata, T., "Restoration Planning System for Earthquake Damaged Gas Pipeline Network",

Proceedings of the Trilateral Seminar-Workshop on Lifeline Earthquake Engineering,

National Taipei University, Taipei, Taiwan, 1985.

397
TABLE 1 Link Data Created from a Coverage

000000000111111111122222222223333333333444444444455555555556666666666777777

1?T4.Sfi7RQ01?T4Sfi 7R9m?^4.Sfi7nq01?T4SP 7flqm?-14-S67Rqm?34Sfi7flq01?34.S67nq01?34 5

1 LINK 30

2 1 1 2

1

1

9

6 .4 88 7 6 20 2 10 . 00000 0 .0600 0 0400

3 2 2 2 6 ? s 1X T 1 S 7 6 20 2 10 00000 Q . 0600 0 0400

3 3 1

1

X X

-) AH * X o o

1X nnonn n 0 , 0060

5 4

y

c. X1 X . qJ 1X 7/ / D . ^ V J X V

nKf £u 3 11 1 A

. ^ u i u . UUUUU Au . U bUU AU

/ c

0 b

-J I U 1 . / b i ( b i\S / 1 U . uuuuo A A £ A A A

u

A yl A A

Q 1 / 9 2

1

5 .041 / b 20 2 1 0

A A A ri

. 00000 0 .0 600 0 .04 00

9 8 8 6 9 1 .415 76 20 1 10 . 00000 0 . 0300 0 0200

1

0

9 9 19 27 8 .202 76 20 2 10 . 00000 0 .0600 0 04 00

1

1

10 10 16 1

1

4 .035 76 20 2 10 . 00000 0 . 0600 G .0400

1

2

1

1

1

1

25 2 4 5 .512 76 20 2 10 00000 0 ,0600 0 0400

1 3 12 12 23 16 4 . 678 7 6 20 2 10 00000 0 ,0600 0 0400

1

4

1

3

1

3

10 8 2 .245 76 20 2 10 00000 0 .0600 0 0400

15 14 14 9 8 2 .856 76 20 2 10 00000 0 0600 0 0400

1 6 15 15 23 24 6 565 76 20 2 10 00000 0 0600 0 0400

1 7 1 6 16 26 27 3 859 76 20 2 10 00000 0 0600 0 0400

18 17 17 8 14 2 602 40 64 4 3 00000 0 0192 0 0240

19 IB 18 2 4 2 537 40 64 4 3 00000 0 0192 0 0240

20 19 19 26 22 2 739 40 64 4 3 00000 0 0192 0 0240

21 20 20 11 5 4 046 76 20 2 10 00000 0 0600 0 0400

22 21 21 5 2 6 169 76 20 2 10 00000 0 0600 0 0400

23 22 22 18 24 6 865 50 80 3 3 00000 0 0180 0 0180

24 23 23 18 13 2 722 50 80 3 3 00000 0 0180 0 0180

25 24 24 13 5 3 700 50 80 3 3 00000 0 0180 0 0180

26 25 25 13 17 1 985 40. 64 4 3 00000 0 0192 0 0240

27 2 6 26 7 12 3 066 50. 80 3 3 00000 0. 0180 0 0180

28 27 27 12 18 3 215 50. 80 3 3. 00000 0. 0180 0. 0180

29 28 28 12 15 2 349 50. 80 3 3 . 00000 0. 0180 0. 0180

30 29 29 15 19 2 . 383 50. 80 3 3. 00000 0. 0180 0. 0180

31 30 30 15 20 1 . 554 40 . 64 4 3 . 00000 0. 0192 0. 0240

Record 1 1-5 A5 LINK

6-10 15 The number of links

Record 2-

I- 5

6-10

II- 15

16-20

21-30

31-40

41-45

15

15

15

15

F10.3

FI0.2

15

46-55 F10.5

56-65 F10.4

66-75 F10.4

Sequential record number

Link ID number

Startinf node ID

Ending node ID

Link length (km)

Pipe diameter (cm)

Pipe element

(in the flow formula)

Efficiency of inspection (day/km)

Efficiency of repair (day/break)

398
TABLE 2 Node Data Created from the Coverage

0000000001111111111222222222233333333334 4 4 4 44 4 44 4 l?34 567fl901?34.S67flqQ1734.S67fl901 2345678901234 56789

1 NODE 27

2 1 1 1 4400 1 .00 17 000

3 2 2 0 0 1 .00 0 .000

4 3 3 2 0 1 .00 0 000

5 4 4 1 2200 1 .00 12 000

6 5 5 0 0 1 .00 0 000

7 6 6 2 0 1 .00 0 000

8 7 7 0 0 1 .00 0 000

9 8 8 0 0 1 .00 0 000

10 9 9 0 0 1 00 0 000

11 10 10 1 3000 1 00 21 000

12 11 11 0 0 1 00 0 000

13 12 12 0 0 1 00 0 000

14 13 13 0 0 1 00 0 000

15 14 14 1 2600 1 00 14 000

16 15 15 0 0 1 00 0 000

17 16 16 1 3800 1 00 19 000

IB 17 17 1 2400 1 00 11 000

19 18 18 1 4200 1 00 20. 000

20 19 19 0 0 1 00 0. 000

21 20 20 1 2000 1 00 13 . 000

22 21 21 1 3200 1. 00 17 . 000

23 22 22 1 2800 1

00 10. 000

24 23 23 1 4000 1

00 18. 000

25 24 24 0 0 1. 00 0. 000

26 25 25 1 3600 1. 00 15. 000

27 26 26 0 0 1. 00 0. 000

28 27 27 1 3400 1. 00 16. 000

Recprd 1 1-5 A5

6-10 15

Record 2-

I- 5 15

6-10 15 II- 15 15

16-22 17

23-28 F6.2

29-38 F10.3

NODE

The number of nodes

Sequential record number

Node ID number

Node type

0: Junction

1; Regulator

2: Source

The number of customer

Social Importance

Total length of LP lines connected to the regulator (km)

399
TABLE 3 The Occurrence Rate of Pipe Failure

r j = Ci • 10 C3)

r j: The occurrence rate of pipe failure

I : MMI scale

PIPE CONSTANTS

ELEMENT Cl C2 C3

1 0.00937 0.33800 10.2

2 0.06560 0.33800 10.2

3 3.28000 0.33800 10.2

4 3.28000 0.21300 13.6

* PIPE ELEMENT

1: Welded Steel pipes with Arc Welded Joints (WSAWJ) - X-Grade

2: Welded Steel pipes with Arc Welded Joints (WSAWJ) - Pre-Modem

3: Welded Steel pipes with Gas Welded Joints (WSGWJ)

4: Cast Iron and Others

400
MEDIUM PRESSURE (MP)

LINES

® SOURCE

O REGULATOR

LOW PRESSURE (LP)

LINES

FIGURE 1 The Medium Pressure (MP) Lines and

the Low Pressure (LP) Lines

401
c

(1)

ARC/INFO DATA BASE

SEISMIC INTENSITY

fMMI SCALE')

C

1 (3)

NODE DATA

(5)

PIPE BREAKS

IN MEDIUM PRESSURE

LINES (Dlj )

PIPE BREAKS IN

LOW PRESSURE ( Dn i ) Dni = r *Lti

Monte Carlo

Method

r : Occurrence

Rate of Pipe

Failure

Lti : Total Length

of LP Lines

LINK DISTANCE ( Ldj)

Ldj = p/Qdj+ q* tj

(8)

SHORTEST PATH

FROM SOURCE TO

REGULATOR

Qdj = Y Vd^Lj

tj = a*Lj + b *Dlj

dj : Pipe Diameter (cm)

Lj : Pipe Length (km)

a : Efficiency of Inspecdon

(day/km)

b : Efficiency of Repair

(day/failure)

Lj : Pipe Length (km)

p, q, 7 : Constants

(7)

NODE WEIGHT (Nwi)

Nwi = p i * Nc i / Dn i

Nci : The Number

of Customer

pi : Social

Importance

J?)

LINK WEIGHT ( Lw j ) Lwj = Z Nwi

REPAIR PRIORITY

FIGURE 2 GENERAL FLOW OF

DETERMINATION OF REPAIR PRIORITY OF LINKS

402
403
NODE NUMBER

LINK NUMBER

SOURCE

REGULATOR

SHORTEST PATH

LINK LINK

NUMBER WEIGHT

1 Nw3+ Nw2

2 Nw3

3 Nw2

4 Nw7 + Nw6 + Nw5 + Nw4

5 Nw7 + Nw6 + Nw5

6 Nw5

7 Nw7+ Nw6

8 Nw6

9 Nw7

10 Nw7

11 UNDEFINED

12 NwB

13 NwS

14 Nw9

15 NwS + Nw9

16 UNDEFINED

17 UNDEFINED

18 Nwll

19 Nw8+ Nw9+ NwlO

FIGURE l\ An Example of the Definition of Link Weight

404
1.0

o

II

II X

<

o

II

II X

<

LUz

0.8

0.6

^ 0.4 H

LU 0.2

0.0 1 I lU

cMco'<^incDr^oooio-i— c\jco'^io<x)r^<x)a)o-^c\jcorrincDr^coCT)o

^T-T-,--,-i--.-T-T-^C\iCNJC\JCMCVCMC\JCMC\JC\lCO

LINK NUMBER

LINK WEIGHT : MMI SCALE = VIII

cvicoTtLncDr^co<^OT-c\i(r)T}-i/><£)r^ooa)0'>-c\ico'^Lnc£)r^coCT)0

i-i-T-.,-T-T-'^T-->-T-CMC\JC\lC\JC\IC\IC\JC\IC\JCM(r)

LINK NUMBER

LINK WEIGHT : MMI SCALE = IX

FIGURE 5 Averaged Link Weight

405

VII. SOCIOECONOMIC IMPACTS

"Lifeline Earthquake Hazard Zonation in

Socioeconomic Aspects"

£. Kuribayashi

"Organizational Features of U.S. Lifeline Systems

And their Relevance for Disaster Management"

K.J. Tierney

"A Methodology for Assessing the Risk of Hazardous

Materials Release Following Earthquakes - A Demonstration Study for the Los Angeles Area"

H.A. Seligson, R.T. Eguchi, K.J. Tierney

407

LIFELINE EARTHQUAKE HAZARD ZONATION IN SOCIO-ECONOMIC ASPECTS

E.Kuribayashi

Professor

Dept. of Civil Eng. /Regional Planning,

Toyohashi University of Technology, Toyohashi, Japan

TEL: 81-532-47-01 11 EXT.714

FAX:81-532-48-2830

ABSTRACT

Within the context of earthquakes, urban lifelines are defined as transportation, water, gas, sewer, power, telecommunications and computer networks.

Experiences from recent earthquake disasters in the North American continent

seismic zones, Japan and the Mediterranean have provided lessons on measures to be taken for the protection of urban lifelines.

Concerning the aspect of zonation, these events are categorized in three

types of recovery of functions in lifeline systems:

1) EMERGENCY repairs, 2) ALTERNATIVE measures and 3) SUSPENSIVE functions.

G. Suzuki

Graduate Student, Dept. of Civil Eng./ Regional Planning,

Toyohashi University of Technology, Toyohashi, Japan

409
INTRODUCTION [13C23

"Urban lifeline systems," or "lifelines," includes the following four kinds of

networks:

1) . Transportation systems through land, sea, and air: moving people and

goods for multiple purposes, in many directions by road, railway,

waterway and airway.

2) . Water supply and sewer treatment systems: reserving, pumping, disposing,

and letting natural flow occur through waterworks, sewerage, and urban

rivers.

3) . Energy supply systems: continually supplying power sources, luminous

sources and heat sources such as electricity, city gas and other fuels,

steam, and cool air.

4) . Communication and computer network systems: exchanging, transmitting

and broadcasting information by telephone, telegram, mail, newspaper,

radio, and T.V., and readying money and money orders by, for example,

cash dispensers. [3]

These systems show the nature of the public, and are not only indispensable in

presenting one state or city, but also have a close relationship with daily

lives.

These systems also consist of two phases, the equipment itself and its

operation. Each system is rationally intertwined with the others. These four

systems are also implemented according to their necessity. The more they are

implemented, the more convenient daily living becomes.

However, what circumstances would result if a part of the system were damaged

because of a disaster or warfare? Is it possible, especially, in the case of an earthquake, to prevent this ?

Dealing with these problems, there is the question if it is possible to get some

resolutions from the inductional or analytical method. If it's not, what are

the other ways? Can we find any effective countermeasures by using the

deductional methodwhich stands with the common sense of prevention of

disasters?

410
INCEPTION

The concept of "lifeline systems" was originally discussed by Prof. CM. Duke

C2][4], because of the disaster brought by the San Fernando earthquake with a magnitude of 6.4 on the Richter scale which struck the northern part of the

city of Los Angeles on February 9, 1971, [4]. In the past, the concept had been

only the group of facilities consisting of points and lines, but then Prof. Duke

provided the new concept including their functions.

EXAMPLES OF THE SAN FERNANDO EARTHQUAKE OF 1971 [4]

In this earthquake. Interstate Freeway 5 named the "Golden State Highway",

which is located on the coast of California, was greatly damaged at the interchange with the road to the inland areas of northern Los Angeles, San

Fernando and Palm Dale. It caused a large interference with traffic on the

north-south and coast-inland links. Fortunately, the national highway 1,

which runs parallel to the Interstate 5, had no serious damage so the traffic

was not held up.

The Van Norman dam had also suffered damage and it caused problems with the

water intake from San Fernando reservoir which is used as one of the main

water reservoirs for the city of Los Angeles. It was also fortunate that other

water supplies were available such as the waterway from the northern part of

California and other reservoirs.

Furthermore, one of the large electrical power transformer stations broke

down, and the transmission stopped for several days in San Fernando. Damage

to telephone system itself was not significant, but the excessive load of calls

paralyzed its transmission function. There were some hindrances to the gas

service. Pacific Gas and Electric Company received several times more

complaints than usual. However, the earthquake was relatively small (M=6.7)

and fortunately its epicenter was located in a mountainous region in

non-residential area, thus causing less chaos.

EXAMPLES IN JAPAN [5]

At the Miyagi-ken Oki earthquake with a magnitude of 7.4 on June 16, 1978, at

one of national expressways, Tohoku-do, the extension of traffic had been

regulated through rampways attached along the expressway which flowed into

411
an area within Miyagi prefecture. There consequently was no damage to the

expressway, but the traffic was restricted by the provisions of a regulation

that, in such a case, presumed that the facility was forced with abnormal

external forces, exceeding certain prescriptions. The supervisor of the

expressway had to close the expressway until the whole line could be inspected

visually, and safety confirmation could be made. On the other hand, a strange

phenomenon was observed where regular roads had to be opened for emergency

transit even if they were possibly damaged by the earthquake. One part of a

local road in the city of Sendai took 267 days to restore, of course the road

itself, and moreover the buried facilities. When a road has some additional

services such as aerial lines for electricity and/or telephone and underground

piping, other than the normal function of "traffic services", its recovery

requires a longer period of time. But some municipal governments have set

such a system of priorities, similar to tose in the United States, for buried

facilities on private property along the roadsides. These "Right of Way"

regulations greatly contribute to shortening the term of restoration.

On the other hand, it was impossible to ward off the affluence of undisposed

sewage and sludge into the river and sea, no matter how well it was regulated

right after the disaster. The disposal system was not part of the same process

of restoration as the water supply system. The water supply system should

require an especially early recovery since potable water is a necessity to

human life. As for the sewage system, it also had the problem that rain water

mingling with it. Consideration will be needed for improvement of maintenance

on the facilities and operation of the systems to avoid contaminating the dark

water in rivers, lakes and seas in view of long term pollution.

At this earthquake, telephone congestion had occurred, but it calmed down

within 24 hours, at the evening of the next day. This phenomenon would appear

in any country where telephone systems are in common use, and it usually would

calm down within a day.

PECULIAR EXAMPLES C5]

Since the stricken area was a rural area, it was not a large-scale disaster by

the Southern Italy earthquake with a magnitude of 6.9 on November 23, 1980.

However, there was unusual type of trouble that occurred in a place 100km away

from the epicenter. There were many relief parties, private organizations sent

from the north, that triggered a traffic jam at the interchange of Expressway

2, in a suburb of Naples. It took many hours to tranquilize the traffic with

412
systematic traffic control. This is an example of indirect chaos caused by an earthquake.

On the contrary, the El Asnam earthquake with a magnitude of 7.3 on October

10, 1980, destroyed a city in the northern part of Algeria. It destroyed the

whole city of El Asnam which was established by the former suzerain state

France, including its disposal system, power supply, city gas and telephone

lines, sewer treatment plants, storage facilities, residential houses, store,

school, market, and governmental buildings. Damage was so extensive that the

whole city had to be abandoned.

EARTHQUAKE RESISTANCE IN LIFELINE FACILITIES [6]

Distribution of property loss ratios, converted from loss of various kinds of

facilities in terms of money value induced from material damage caused by

earthquakes occurring in Japan during a 13 year period from 1962 to 1975, is

shown in Fig. 1.

A

Loss Ratio of Property Loss

FIGURE 1. Characteristics of individual Loss Ratios

of Various Kinds of Facilities [6]

413
The loss ratios of building and highway facilities are almost of the same

degree, and also close to the loss ratio of the total loss. In contrast to this,

the loss ratios of agriculture, flood control, and river and harbor facilities

have a greater value than the loss ratio of the total loss, but those of

electrical power, telecommunication and water supply facilities are less.

Distribution of the individual loss ratio for highways is shown in Fig. 2. It includes six earthquakes from the Miyagi-ken Hokubu earthquake in 1962 to the

Ohita-ken Chubu earthquake in 1975.

It is slightly meaningless to compare the individual loss ratios in different

earthquakes since the damaged area depends on the administrative district, but

it is significant to compare the individual with the total loss ratio. For this reason. Fig. 3 shows the details of the distribution of the individual loss ratio

for buildings.

When the loss ratios for buildings and highways are considered, the tendency

of the loss of these two facilities used by humankind since ancient time is

almost the same as the total loss. In contrast to this, the loss ratio for the

facilities which only have a hundred-year or less history, but have high

productivity, including such modern facilities as electrical power,

telecommunications and water supply, are lower than that of the total. The

greater value of the loss ratio, therefore, makes larger earthquake disaster

loss ratios closer to that of the total loss.

On the other hand, the individual loss ratio for harbor facilities is larger

than that of the total. Due to the location of the harbor facilities, one

should understand from this that the external forces that mainly have to be

considered are the waves and the tides. The individual loss ratio will be one

of the criteria in estimating the earthquake resistance of lifeline facilities.

It is probable that these facilities have a lower loss ratio and surpass others

in earthquake resistance.

414
FIGURE 2. Relationships between Loss Ratios of

Property Loss and Highway Facility [63

Loss Ratio for Property Loss

FIGURE 3. Relationships between Loss Ratios of

Property Loss and Buildings C6]

415
FUNCTIONAL LOSS OF LIFELINE SYSTEMS [5]

The recovery of major lifeline systems at the Miyagi-ken Oki earthquake in 1978

is shown in Fig. 4. It took a relatively long period ofd time to get them back

on line, especially roads, railway, and city gas. However, having had

alternatives, the roads did not cause major difficulties for transportation.

Telecommunication

Quake occurred June 1978 July 1978

FIGURE 4. Resumption of Lifelines in the Miyagi-ken oki

Earthquake of June 12, 1987 (after PWRI)

What are the methods for making recoveries quick? Fig. 5 shows an example

from the Miyagi-ken Oki earthquake. It is obvious that the damage to key

facilities like bridges takes longer to restore than the damage to such

line-like facilities as roadways.

In Fig.6, it can be hypothesized that when there are fewer alternatives

available and/or there are weaker key facility, more time is need for recovery.

416
©3.3%

(5)4.3%

13.0%

(2) 2.2%

(3) 2.2%

(7)

Legend

Obstacles fallen

Trees fallen

Damage to buried articles

Damage to shoulders

Settlements near

bridge abutments

Slope failures besides road

Damage to bridges

Lamped rocks fallen

Irregularity of road surface

(DlO.0%

(D5.0%

®2.6%

/-(D5 .3%

®10.5%

(!) 36.8%

(1)5.3%

(D

39.5%

/-(D6.1%

(6)9.1%

(!) 39.4%

(D6.1%

-^5

(D

39.4%

©3.5%

©10.3%

©

44.8%

(8)6.9%

®

34.5%

A(92) B(40) C(38) D(33)

Number of traffic control

E(29)

A: Immediately after the quake

B: One week or more C: Two weeks or more

D: Three weeks or more E: One month or more

FIGURE 5. Recovery of highway traffics after the

Miyagi-ken Oki Earthquake (after PWRI)

417
U

:3

4-> Easy or Hard Easy

•H

H

•H

u

Trend in easy resumption

0)

>

•H

-P

fdc

0) Hard Easy or Hard

+J Q)

rH n-\

-P

Terminal Facility Linelike Facility

FUNCTIONAL RECOVERY OF THE LIFELINE SYSTEMS C5JC7]

The considerations for damaged lifeline systems after an earthquake could be

patterned as follows:

The following are examples of the above:

EMERGENCY repairs: In the Nihonkai-Chubu earthquake with magnitude of 7.7 on May 1983, the national highway 7, which linked the city of Akita and Noshiro,

was temporary out of service around Noshiro in the Asauchi region, because of

settlement of an underground channel. As a result of emergency repairs, its

function was restored in twelve hours after the shock.

FIGURE 6. A Scheme of Resumption

for Lifelines C7]

(1) EMERGENCY repairs

(2) ALTERNATIVE measures (A)

(S)

(E)

(3) SUSPENSIVE functions

418
In the Algeria-El Asnam earthquake, the national highway which runs from the

capital Algiers to Oran via El Asnam, had closed due to fault movement of 4.2

meters in the maximum gap. But the recovery was made by mending the part of a by-pass which was fortunately under construction. It was completed within 2 hours after the shock.

ALTERNATIVE measures: These will need to be taken for water supply,

electrical power, gas, telecommunications and broadcasting. It is needless to

say, but a tanker would be used for the emergency potable water supply.

SUSPENSIVE functions: This would be a rare occurrence in a post-quake situation. In the Izu-Ohshima Kinkai earthquake with a magnitude of 7.0 on January

14, 1978, a prefectural highway in a mountainous area linking Shuzenji and

Shimada was damaged, with the high possibility of a secondary disaster.

Partial service was restored using a makeshift road, and full service was

resumed 2 years later with a different new road. In other words, the previous

road was abandoned. Another example is the case of the El Asnam earthquake,

mentioned above.

An extrapolation can be made using these three items, E, A and S with the

following two criteria: "Availability of a function after an earthquake" and

"Extent of earthquake damage."

If utility services are not functioning according to generally accepted standards, the mutual relationship of E, A and S should be considered. Optimum

considerations are shown in (a) and (b) of Fig. 7 and Fig. 8, respectively.

The relationship among each of the two criteria above and E, A and S is shown

in (c) and (d) in Fig. 7 and 8, respectively. A closed quadrilateral is drawn in

the figures. In both of the figures, as the quadrilaterals get smaller, they

show the much greater capability of functions and the less extent of damage.

If the lines do not form a complete quadrilateral, it implies the lack of

balance in the countermeasures before earthquakes.

419
FIGURE 7. Multi-Relationships

in E,A,S and RF [7]

FIGURE 8. Multi-Relationships

in E,A,S and DA [7]

In general, it seems that the state of the suspensive functions is not

acceptable. However, it is important to have provisions for realistic

situations and constantly assuming the possibility of non-ideal situations.

420
CONCLUSIONS [7]

The following provisions must be made through the study of lifeline disasters:

(1) The system must have a redundant functional capacity as much as possible,

(2) The system must have economical alternatives to keep its function,

(3) The system must have measures to quickly recover the function after an earthquake, and

(4) The system must be improved in its earthquake resistance.

There are various types of lifeline systems today. Each bears close relationship with another, for example, covering the whole of Japan and making the

Japanese islands into one big city. In many aspects, they bring greater convenience to daily life, but may possibly have some weak points when disasters

occur.

It is desirable not only to consider each individual system or facility, but

also to estimate and undertake the critical study of the system as a whole. A

higher density of lifeline systems leads to an easier life, but also contains the

possibility of sudden inconvenience or uneasiness in case of a disaster in an urban area. These disadvantages could possibly lead to a critical situation,

especially in a large modernized city.

A lifeline system in a city is the equivalent of an artery or a nerve in a human

body. It is impossible to strengthen such lifeline systems without strengthening the infra-structure of a whole city and to strengthen a city without

strengthening lifeline systems, a good examples being the disaster caused by

the Loma Prieta earthquake (M=7.1) occurred near San Francisco, California,

U.S.A., on October 17, 1989. [8]

FUTURE DIRECTIONS

To improve earthquake resistance on each lifeline system in accordance with its

importances, it is greatly recommended that study on geographic characteristics should be developed. It includes informations from basic conditions, such

as physical conditions to much complex data of regional socio-economical conditions.

421
ACKNOWLEDGEMENTS

This research was supported by a grant from subsidy of Science Research Fund,

Ministry of Education, Science and Culture through 1989 to 1990 fiscal year:

this support is gratefully acknowledged.

REFERENCES

1. Duke, CM. and Mo ran, D.F., "Earthquakes and City Lifelines", San Fernando

Earthquake of Feb. 9, 1971 and Public Policy, Joint Committee on Seismic Safety

of the California Legislature: pp. 53-76, 1972

2. Duke, CM. and Moran, D.F., "Guidelines for Evolution of Lifeline Earthquake

Engineering," Proc, National Conference on Earthquake Engineering,

pp. 367-376, Amm Arbpr, Michigan, 1975

3. Thiel,C., "Lifelines, Seismic Hazards and Public Policy", Social and Economic

Impact of Earthquakes on Utility Lifelines, pp. 6-17, ASCE, 1980

4. San Fernando, California, Earthquake of February 9, 1971, Vol. , and , U.S.

Department of Commerce, National Oceanic and Atmospheric Administration, 1973

5. Kuribayashi, E. et al., "A Review of Earthquake Disaster Preventive Measures

for Lifelines", Proc, 8th World Conference on Earthquake Engineering, Vol.8,

pp. 185-192, San Francisco, 1984

6. Kuribayashi, E. and Tazaki, T., "An Evaluation Study on Disaster-Distribution

Characteristics of Property Losses Caused by Earthquakes", Proc, Japan

Society of Civil Engineers, No. 292, pp. 75-81, 1979

7. Kuribayashi, E., "Preventive Measures for Urban Lifelines during Earthquake

Disasters", Japanese Scientific Monthly (Gakujutsu Gettupo), Vol.39, No. 11,

pp. 13-18, Nov. 1986, written in Japanese

8. Housner, G.W., "Competing against Time", A Report to Governor George

Deukmejian, May, 1990

422
ORGANIZATIONAL FEATURES OF U. S. LIFELINE SYSTEMS

AND THEIR RELEVANCE FOR DISASTER MANAGEMENT

Kathleen J. Tierney

Department of Sociology and Disaster Research Center

University of Delaware

ABSTRACT

Disaster-generated damage and disruption to lifeline systems

produce a variety of impacts, ranging from direct effects, such as

physical damage and service supply interruption, to indirect

impacts, such as forced relocation of community residents, threats

to ongoing social and economic activity, and delays in the disaster

recovery process. Engineering studies focus primarily on the

physical vulnerability of lifeline systems and on the technical

aspects of mitigating disaster damage. Few studies have addressed

the organizational properties of lifeline systems, their

interrelationships, or their linkages to broader community disaster

preparedness and response efforts. This paper highlights lessons

learned in a recent Disaster Research Center project focusing on

the performance of lifeline organizations in major community

disasters. The paper discusses disaster management strategies at

the organizational level as the outcome of three sets of factors:

the structural features of the organizations that provide lifeline

services; the institutional environment in which lifeline systems

operate; and the task-related demands faced by lifeline

organizations.

INTRODUCTION

Engineers are concerned with lifelines as physical systems.

Their analyses focus primarily on the physical properties of

lifelines, such as design features, materials used in construction,

system configurations, capacities and outputs, and the spatial

distribution of facilities and system components. In attempting to

understand issues related to hazard mitigation, preparedness,

response, and recovery, engineers are likely to place most emphasis

on the physical or material side of the lifeline problem.

In contrast, sociologists are interested in lifeline service

providers as organizations. Their analyses focus on the

distinctive organizational properties of lifeline service providers

and on the implications these organizational features have for

disaster mitigation, preparedness, response, and recovery. In

sociological approaches to the study of the lifeline problem,

variables such as organizational structure, organizational

adaptation processes, interorganizational relations, and

organizational domains, tasks, and resources are seen as important

influences on organizational performance.

423
In recent years, non-technical issues related to lifeline

system performance have begun to receive more attention. For

example, in a series of workshops and proceedings, the Building

Seismic Safety Council (1987) identified a range of social factors

that affect how lifeline organizations manage earthquake hazards

and pointed out the need for research to better understand how

these factors operate. That same report cited research findings

that indicate that, except for a select group of organizations in

high-risk areas of the U. S. , lifeline service providers generally

lack knowledge of the hazard and are far less committed than they

could be to hazard reduction.

This paper discusses organizational features of the lifeline

service provision system in the U. S. and illustrates how these

features influence disaster planning and response activities .The

examples and cases discussed in the paper were developed from a

study that focused on disaster the preparedness and response of U.

S. lifeline organizations. That project involved the collection of

data on disaster preparedness activities among lifeline

organizations in four U. S. communities and lifeline system impacts

and organizational response activities in seven communities

affected by recent U. S. disasters, including Hurricane Hugo and

the Loma Prieta earthquake.^ The study involved the collection of

data on various types of lifeline organizations, including

providers of natural gas, electric, water, and telephone services;

transportation departments; port authorities; solid waste

management organizations; and departments of public works. The

sections that follow discuss what was learned in the course of the

study about the organization of lifeline services in the U. S. and

the impact organizational variables have on disaster management.

ORGANIZATIONAL AND ENVIRONMENTAL FACTORS

AFFECTING DISASTER MANAGEMENT

A number of academic and applied disciplines, including

management and business administration, are predicated on the

notion that organizational form makes a difference in

organizational performance. Given a particular set of goals for an

enterprise, some ways of structuring that enterprise and organizing

its members are better than others for achieving those goals in a

particular societal and historical setting. Organizational

performance and effectiveness can thus be attributed in part to

organizational form. Examining alternative modes of lifeline

system organization and their impact on organizational behavior

^ The four communities in which DRC conducted studies on

organizational and community preparedness were Seattle, Washington;

Richmond, Virginia; Buffalo, New York; and Portland, Oregon. Postdisaster response studies were conducted in Hamden, Connecticut;

Charleston, South Carolina; Charlotte, North Carolina; and in Santa

Cruz, San Francisco, and Oakland, California.

424
should provide useful insights on what features enhance their

effectiveness and what features interfere with more effective

performance with respect to disaster management.^

The kinds of disaster management strategies that lifeline

organizations in the U. S. have developed and implemented are the

result of complex sets of factors. For purposes of this

discussion, three categories of factors will be discussed:

properties of lifeline systems; characteristics of the

institutional and societal environment in which lifeline systems

operate; and task-related demands.

Properties of Lifeline Systems

Lifeline systems are characterized by a bewildering degree of

variety and complexity. There are several ways in which the system

is complex. First, modes of ownership vary, both across lifelines

and across communities. Lifeline services may be provided by

public, quasi-public, or private organizations, depending on the

community context.

Different patterns of sponsorship entail different sets of

organizational constraints and incentives. For example, Piatt

(1991) suggests that private utilities may tend to maintain and

upgrade their facilities more readily to enhance their corporate

reputations, shield themselves from liability, and protect capital

investment. Generally speaking, such practices encourage hazard

mitigation. On negative side, private utility providers are likely

to be less well-integrated than public utilities with communitywide public sector disaster planning efforts, which can hamper

efforts at interorganizational co-ordination in disasters.

Government-owned utilities suffer from neglect during times of

fiscal crisis and are more subject than private providers to the

vicissitudes of the political process.

Recently, there has been a marked trend toward "privatization"

of services in the U. S. (David, 1988). Services that were

formerly provided by public entities, including services such as

garbage removal and sanitation, are increasingly being sold off or

contracted out to private entities. This trend has also added to

the complexity of lifeline service provision tasks.

Second, different lifeline services vary in the extent to

which they are consolidated with one another. In some cases, for

example, a single organizational entity supplies more than one

^ The term "disaster management" is used here in a broad

sense. The term encompasses four phases or task areas in which

organizational action can reduce hazards and contain losses: predisaster mitigation and preparedness, and post-impact response and

recovery.

425
lifeline service; for example, gas and electric service provision

are frequently consolidated. In other cases, the services are

separately owned and managed. An individual community may be

responsible for providing the majority of lifeline services within

its jurisdictional area, while a set of separate service providers

may function in a nearby jurisdiction.

Consolidation of lifeline services increases the likelihood

that the organizations involved will consider interdependencies

among utility services in their planning and response activities

and will integrate their disaster management activities. For

example, we observed that in the Loma Prieta earthquake, the fact

that both gas and electric services were provided by a single

organizational entity (Pacific Gas and Electric) helped emergency

response and restoration activities proceed more smoothly. On the

other hand, lifeline service provision by separate organizational

entities appears to hamper integration in planning and response

activities.

A third type of complexity stems from the fact that lifeline

service provision does not follow consistent jurisdictional

boundaries. Some lifeline organizations cover enormous geographic

areas—even crossing state boundaries—while others are confined to

small geographic areas. Mammoth organizations like the California

Department of Transportation, Pacific Gas and Electric, and Bell

coexist with smaller entities that provide service to individual

cities or to special districts.

This jurisdictional inconsistency makes joint disaster

planning and response more difficult for lifeline organizations.

Effective emergency planning and response necessitate ongoing

relationships and interaction among the organizations responsible

for those activities. In order to plan and respond effectively in

disaster situations, service providers with large geographic

jurisdictions must co-ordinate with a range of more locally-focused

organizations that themselves may vary considerably in structure

and function. Inconsistency among jurisdictions greatly complicates

the problem of establishing these interorganizational linkages.

The fact that some lifeline organizations cover very large

geographic areas also means that disaster vulnerabilities may vary

considerably within an organization's area of responsibility.

Large utilities may find themselves overemphasizing some types of

disaster agents (such as those that affect the "home office") and

being insufficiently aware of other potential problems.

Additionally, when lifeline organizations have responsibility for

vast geographic areas, key organizational activities are performed

and decisions are made at considerable distance from the local

communities those functions affect. As a consequence, the central

administrative office of the lifeline utility may lack information

on needs and resources in specific localities and may not have an

adequate grasp of the factors that could complicate organizational

426
performance in a disaster situation.

Some lifelines, such as crude oil and natural gas pipelines,

are operated by organizations that have no counterparts or

representatives at the local level. Local communities, and even

state-level agencies, may not even be aware of the location of

underground pipelines in their jurisdictions, since pipeline

operators are typically not required to provide that information

(Greene and Schulz, 1987; General Accounting Office, 1991). Lapses

in planning and emergency response were evident in recent pipeline

accidents in the U. S. (General Accounting Office, 1991).

Of course, as I note later, the fact that some lifelines are

operated by very large entities can be an advantage. Lifeline

providers with large jurisdictions tend to have large numbers of

employees as well, which means that there is a pool of workers that

can be utilized for repair and reconstruction in disaster

situations. Other things being equal, very large lifeline

organizations are probably also in a better position than smaller

organizations to implement advanced hazard mitigation techniques.

Smaller organizations may lack the financial resources to undertake

needed work and may not consider mitigation cost-effective.

Lifeline organizations with large geographic service areas

almost invariably decentralize many of their operations to the

district level. District offices are likely to be more familiar

than central administrative offices with local community

organizations and local needs, and it is at this level that coordination typically takes place in emergency situations.

A fourth source of complexity is that lifeline systems differ

in the manner in which their components are interrelated.

Centralization, "tight coupling," and interdependence are three

dimensions along which systems can be distinguished. Some lifeline

organizations are more highly centralized than others, in that

damage to a single key facility affects the operation of the entire

system. A high degree of centralization makes a lifeline

organization very vulnerable in a disaster situation, and this is

one reason why lifeline organizations such as telephone and

electric companies try to decentralize their operations and build

redundancy into their systems. However, some key lifeline system

elements—particularly the transmission systems associated with

electricity and water—remain rather highly centralized, in that

they depend particular supply sources.

A related property, "coupling," refers to the extent to which

system components are dependent upon one another in producing an

output, so that damage to one component renders other components in

the system inoperative, even if they remain undamaged. Many

lifeline systems are relatively "tightly-coupled," which adds to

their vulnerability. For example, in Hurricane Hugo, the water

system in Charleston was made inoperative as a result of three

427
factors: damage at the filtration plant; water line breaks that

reduced water pressure; and loss of electrical power for pumping

operations. However, even if the system had not experienced the

last two impacts, the loss of the filtration plant would have been

sufficient to cause the failure of the entire system, because the

operation of the water system depends critically on the plant.

Although electrical system service to the San Francisco area

was restored relatively rapidly following the Loma Prieta

earthquake, the power supply system was highly dependent on the

continued functioning of Pacific Gas and Electric power generation

facilities, which sustained severe damage. Because of this

relatively "tight coupling," failures in those components led to

failure of the entire power supply system.

In contrast, although the damage to the Bay Bridge and the

loss of that transportation route for one month following the Loma

Prieta earthquake presented severe problems for the Bay Area,

transportation difficulties were comparatively easy to overcome,

because the transportation system is a "loosely-coupled" and

redundant system. The transit system was not paralyzed in the Bay

Area, because the subway system and an expanded ferry

transportation system were capable of functioning as enhanced

alternative transportation lifelines following the disaster.^

Finally, rather than operating in isolation from one another,

lifeline systems are interdependent. The most obvious

manifestation of this interdependence is the reliance of other

lifeline functions on electrical power. Electrical power is

fundamental to the operation of most other systems, and electrical

failures can render other lifelines inoperable even in the absence

of direct damage. In Hurricane Hugo, for example, the widespread

loss of electrical power affected water distribution systems, waste

water treatment systems, local telephone PBX systems, traffic

signals, port operations, and other lifeline services. In nonurban areas, communities and households on well systems were unable

to pump water. There was an intense demand for emergency

generators and for generator fuel following the hurricane, because

so many facilities that depend on power needed to be operational.

Extensive dependence upon electrical power also meant that

there was conflict about power restoration priorities in some of

the disaster-stricken communities we studied. Since in many cases

^ The term "coupling" is used in this paper primarily to

refer to the physical components of lifeline systems. This concept

also has an organizational dimension. Organizations can attempt to

partly compensate for "tightly-coupled" technologies by devising

organizational solutions. For a more through discussion of

"coupling" in physical and organizational systems, see Perrow,

1984.

428
disaster damage and impacts were unanticipated, priorities had to

be established on a case-by-case basis during the emergency period.

Many of the lifeline organizations we studied failed to

appreciate the extent to which their own operations were dependent

on other services and failed to take interdependence into

consideration in their mitigation and preparedness activities.

However, as noted earlier, in situations in which lifeline

functions are consolidated, e.g. , in combined gas and power

companies, lifeline interdependence is better understood, and coordination of emergency response and restoration activities is less

difficult.

The Institutional Environment

Like all organizations regardless of function, lifeline

organizations are affected by their environments." Many of their

activities can be traced directly to requirements imposed by

outside organizational actors, and the somewhat uncertain and

inconsistent environment surrounding disaster management

requirements for lifeline organizations has had an impact on the

measures these organizations have adopted. The general climate for

lifeline organizations might best be described as a combination of

a laissez-faire approach and the setting of minimal performance

standards. These points are elaborated below.

General Absence of a Requirement to Mitigate and Prepare for

DisastersLifeline organizations are generally aware of the need

to prepare for emergencies that affect organizational functioning.

Many lifeline organizations are also aware of the need to engage of

mitigation and preparedness for major natural disasters. Some

lifeline organizations have concentrated considerable effort on

developing hazard mitigation, preparedness, and response

capabilities. However, such actions, when undertaken, are largely

done voluntarily, not in response to any specific requirements or

regulations. In this respect, lifeline organizations can be

contrasted with organizations such as hospitals, which are required

to engage in disaster planning and to conduct regular disaster

exercises as a condition for accreditation.

As noted earlier, effective disaster response, restoration,

and recovery effort are typically based on extensive pre-disaster

contact and collaboration among responding organizations. In the

community studies we conducted, we found several instances of

frequent pre-disaster contact and joint planning between lifeline

" For purposes of this discussion, the "environment" consists

of other organizational actors external to the various lifeline

organizations, including agencies at the various governmental

levels, regulators, and other organizations whose activities affect

the provision of lifeline services.

429
organizations and other community response organizations, such as

local emergency management agencies. However, we also observed

situations in which pre-disaster contact between key lifeline

providers and other critical emergency responders was minimal and

in which the lack of pre-planning resulted in co-ordination

problems during the emergency period. When preparedness networks

developed, they were the outcome of distinctive local circumstances

and local history, rather than specific mandates to engage in joint

disaster management efforts.

The societal environment also affects the behavior of lifeline

organizations with respect to pre-disaster mitigation measures. In

a recent paper. Buckle (1991) notes that several barriers impede

improved hazard earthquake mitigation for lifeline systems. Among

these barriers are an absence of authoritative codes and standards

for seismic design and construction and for retrofitting existing

structures. In the absence of clear standards and guidelines,

decisions about mitigation are left in the hands of individual

organizations and design professionals. A recent Federal

government mandate requiring the development of seismic performance

standards for lifelines may ultimately change organizational

mitigation practices for earthquakes, but that impact will not be

felt for quite some time.

Currently, some lifeline organizations (typically those with

abundant resources and those with considerable disaster experience)

are very capable of coping with large-scale disasters. For example,

several California utilities we studied had invested extensively in

both mitigation and preparedness for disasters, particular

earthquakes. However, this is not a national pattern; lifeline

organizations generally do not give hazard reduction a high

priority. In the mitigation area, for example, use of buried

electrical lines rather than aerial lines cuts down on wind damage.

Both of the two major electrical utilities we studied following

Hurricane Hugo were still using above-ground lines at the time of

the disaster, and consequently the damage to the electrical

distribution system was devastating.

In short, as a consequence of the laissez faire environment in

which lifeline organizations undertake their hazard management

activities, a "patchwork" situation exists nationally, in which

some utility services are more reliable than others in disaster

situations, and in which some communities are better served

following disasters than others. Large, wealthy, well-managed

utilities—particularly those with extensive disaster experience

are often superbly prepared for disasters, while their less welloff, less experienced counterparts lag considerably in all areas.

Weak Incentives to Mitigate and Prepare for Disasters. In the

earthquake area. Buckle (1991: 13) notes that for lifeline systems

at the present time "There are no tax policies, insurance

incentives or rate adjustment schemes which encourage owners to

430
either upgrade existing facilities or to use higher design

standards for new systems." Reducing the disaster vulnerability of

lifeline systems can be a very expensive undertaking, involving

replacement, retrofitting of components, and in some cases

relocation of entire facilities. High costs and the absence of

fiscal incentives make hazard reduction impractical for many

lifeline organizations.

Legal liability for injury, damage, and losses resulting from

lifeline failures and service interruption in disaster situations

could conceivably be a factor influencing lifeline organizations to

mitigate and prepare for disasters. At some future time, concern

about liability may begin to motivate lifeline organizations to

mitigate and prepare for disasters. However, at the present time,

the legal and regulatory picture is unclear. States vary

considerably in terms of their legal provisions; in some states,

public and quasi-public entities are immune from liability under

most circumstances. In the absence of credible assessments of the

risks associated with various hazards in specific localities,

formal specifications of performance criteria for lifeline systems

and their components, state and local laws requiring improved

hazard abatement, and assignment of responsibility for the

enforcement of hazard reduction measures for lifeline systems,

liability concerns are not likely to motivate organizations to

improve their disaster management strategies (for more detailed

discussions focusing specifically on the earthquake problem, see

Malik, 1987 and Miller, 1987).

Some lifeline organizations voluntarily engage in costly

mitigation and preparedness programs primarily because they know it

is critical to corporate finances to avoid disaster losses and

associated costs. However, such measures are typically seen as

cost-effective and justifiable only in those regions of the country

where risks are high and disaster experience is extensive. For

example, among utility companies, we did not observe any

organizations in other parts of the U. S. that had the same degree

of commitment to hazard reduction as those in California.

In understanding factors that affect organizational

performance, it is also important to note that most lifeline

organizations are essentially monopolies.^ Obviously, those in key

^ Since deregulation of the telephone industry, long-distance

telephone service is one notable exception to this pattern. Most

consumers are able to choose among several long-distance carriers,

and concern about the quality of telephone service is one factor

that influences that choice. Consumers have some degree of choice

about the transportation systems they use for commuting and other

daily activities, and they typically make those choices based on

quality of service, convenience, and cost. However, choices for

most other utility services are more or less fixed for community

431
positions in these organizations are aware that they provide

critical community services, and they doubtless want to provide the

best possible level of service. However, being prepared for

disasters is typically not a matter of organizational survival for

lifeline providers, as it can be for other organizations. Other

enterprises that fail to cope well with disaster-related demands

can expect to lose business to their competitors, but this is

generally not the case for lifeline organizations. Customers who

are forced to wait for the restoration of their utilities may be

inconvenienced, and the company may lose public good will, but the

company will not cease to operate.

Private utility companies certainly have reason to be

concerned about company profits if they fail to mitigate and

prepare for disasters, but many organizations do not yet think in

these terms. Publicly-owned utilities have even fewer fiscal

incentives to reduce losses and may have much more difficulty

raising the money to make improvements in their systems. Moreover,

public entities, including publicly-owned lifeline organizations

and special assessment districts, can expect to receive Federal

government compensation for their losses in the event of a

Federally-declared disaster.^

Task-Related Demands

To some extent, the ways that lifeline organizations adapt in

disaster situations are an outgrowth of the manner in which these

organizations structure themselves to deal with their day-to-day

service-provision tasks. Unlike many other types of organizations

(e.g, restaurants, banks, commercial establishments in general,

service establishments, and many manufacturing firms), lifeline

organizations, particularly providers of essential utility

services, must be able to deliver service on a continuous basis.

In this respect, lifeline organizations resemble major public

safety and health care agencies (e.g., fire departments, police

departments, hospitals), which must also perform the tasks for

which they are responsible on a more or less continuous basis.

Lapses in lifeline service do occur from time to time, of course;

blackouts, brownouts, and service outages, nonfunctioning traffic

signals, and airport shutdowns are not entirely unknown. However,

generally speaking, utility customers expect a very high level of

residents.

^ Indeed, if used properly, disaster assistance funds may

provide an important vehicle for reducing the disaster

vulnerability of lifeline systems. Federal law requires a that a

proportion of the funds provided to public entities for disaster

recovery be used for the mitigation of future hazards. Community

utility systems could use these funds creatively to mitigate future

losses

.

432
performance from these types of organizations, and lifeline

organizations are structured to meet this expectation.

Distinctive structural properties result from these task

requirements. For example, staffs of major lifeline organizations

are typically large, and some degree of staffing is provided around

the clock. Because of the need to maintain continuous operations,

lifeline organizations invariably have plans and procedures for

"routine," everyday emergencies that might threaten to interrupt

service. Mutual aid agreements are also common among organizations

providing the same services in different geographic areas. These

agreements may involve sharing utility commodities (e.g.,

electricity, water), personnel, or other resources.

All these arrangements help give lifeline organizations

considerable flexibility when they are required to respond to a

major disaster. For example, researchers who study organizational

adaptation in major crisis situations have noted that organizations

alter their structure and functioning in typical ways when faced

with the need to meet excessive demands (c.f., Brouillette and

Quarantelli, 1971). Expansion and extension are two common types

of adaptation. In the first adaptive mode, expansion, the

organization performs the same sorts of activities as it did during

routine times, but many more people are involved in those tasks.

Extending organizations keep their pre-disaster structure, but

engage in new, non-routine tasks.

Large staffs and an organizational schedule that involves

round-the-clock shifts give lifeline organizations a large pool of

trained personnel from which to draw in a serious emergency and

permit rapid organizational expansion in critical situations. In

this respect, they resemble other key disaster response

organizations, such as fire departments, police departments, and

hospitals

.

Mutual aid agreements among lifeline providers also facilitate

expansion in times of crisis. For example, following both

Hurricane Hugo and the Loma Prieta earthquake, power companies

mobilized very large numbers of people quite rapidly. South

Carolina Gas and Electric received assistance from 48 electric

companies in 15 states and expanded its staff of linemen from 95 to

2,600. In North Carolina, Duke Power used 3,000 workers in

emergency response and service restoration, including workers from

40 other power companies throughout the South.'' Lifeline

' Extending patterns were also observed in lifeline

organizations, but these were less frequent and appeared to be more

problematic for the organizations involved. Some organizations had

to both expand and extend. For example, following Loma Prieta, one

urban public works department, in addition to expanding by

mobilizing all its personnel and taking on numerous volunteers.

433
organizations are, in a sense, we11 -structured to expand in major

emergencies. Organizations that have formal agreements and

concrete plans for incorporating personnel mobilized from the

outside obviously have fewer problems in major emergencies than

those that expand in an ad hoc fashion.*

On the negative side, however, the fact that lifeline

organizations are aware of the need to plan for "routine"

emergencies does not mean that they are automatically well-prepared

for major disasters. In the lifeline organizations we studied, we

found that it was quite common for personnel to consider disasters

simply extensions of everyday emergencies. Rather than

representing a quantitative difference in the demands placed on

organizations, a disaster situation requires qualitatively

different tasks, activities, and decisions. Those organizations

that had not taken into account how disasters and ordinary

emergencies differ were forced to use costly time and effort to

improvise new structures and procedures during the emergency

period.

CONCLUDING COMMENTS

Reflecting on the status of disaster management efforts in the

U. S. , Piatt (1991: 173) notes an irony: while our communities may

be safer than ever before from direct threats to life-safety and

direct disaster losses, "indirect economic and personal hardships,

and even threats to life, arise from the failure or disruption of

the vital regional circulatory systems over which the private

individual and often the local government have no control .

Lifelines have clearly not received the emphasis they deserve in

either hazard reduction policy or in practice. Because of recent

dramatic lifeline failures and losses, such as the Nimitz Freeway

collapse in the Loma Prieta earthquake, hazard mitigation for

lifeline systems is receiving more attention in the U. S. In

considering how to reduce the hazards associated with lifeline

performance, along with increasing the resistance of physical

lifeline systems, we must consider ways to increase the

also had to extend its activities into building inspection and

damage assessment, which were entirely new tasks for that

organization. Accomplishing such profound changes in structure and

activities in a crisis situation is extremely difficult for an

organization.

^ However, organizations may not always take into account all

they need to do to successfully manage expansion. For example,

following Hurricane Hugo, several utilities mobilized large numbers

of workers from outside the affected area. The companies were able

to use these workers very effectively in repair and restoration

activities. However, they had neglected to consider how they would

house and feed these additional personnel.

434
organizational capacity of service providers. Determining how

physical systems can be made more resistant, resilient, and

redundant is an important topic for research. It is equally

important to understand how best to employ principles of

organizational design to improve the performance of lifeline

organizations in disasters.

ACKNOWLEDGMENT

The research discussed in this paper was sponsored by the

National Science Foundation, Grant No. CES-8721862, "Preparedness

and Response of Lifeline Organizations in Community Disasters." A

related project that provided additional insight into the lifeline

problem, "Societal Risk Associated with Crude Oil Pipeline Systems

in Areas of High Seismic Risk," is being conducted under

sponsorship from the National Center for Earthquake Engineering

Research. The observations made in this paper are those of the

author; they do not necessarily reflect the views of the funders.

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Brouillette, J. R. and E. L. Quarantelli. 1971. "Types of

Patterned Variation in Bureaucratic Adaptations to Stress."

Sociological Quarterly 41: 39-46.

Buckle, I. 1991. "Improving Earthquake Hazard Mitigation for

Lifeline Systems." Paper prepared for FEMA Earthquake Mitigation

Study Workshop, Alexandria, VA, July 23-24.

Building Seismic Safety Council. 1987. Abatement of Seismic

Hazards to Lifelines: An Action Plan. Washington, D. C. : Federal

Emergency Management Agency. Earthquake Hazards Reduction Series

32.

David, I. T. (1988). "Privatization in America." In The

Municipal Year Book 1988. Washington, D. C: International City

Management Association.

General Accounting Office. 1991. Pollution from Pipelines: DOT

Lacks Prevention Program and Information for Timely Response.

Washington, D. C. : U. S. General Accounting Office. Report No.

GAO/RCED-91-60.

Greene, M. R. and P. A. Schulz. 1987. "Political, Social and

Economic Problems in the Abatement of Seismic Hazards in Gas and

Liquid Fuel Pipelines and Facilities." In Building Seismic Safety

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on Political, Economic, Social, Legal, and Regulatory Issues and

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Emergency Management Agency. Earthquake Hazards Reduction Series

31.

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Malik, L. E. 1987. "Regulatory and Legal Issues in Abatement of

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Seismic Safety Council, Abatement of Seismic Hazards to Lifelines,

Vol. 6: Papers on Political, Economic, Social, Legal, and

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Miller, H. C. 1987. "Public Tort Liability Issues in Community

Lifelines." In Building Seismic Safety Council, Abatement to

Seismic Hazards to Lifelines, Vol 6: Papers on Political,

Economic, Social, Legal, and Regulatory Issues and General Workshop

Presentations. Washington, D. C. : Federal Emergency Management

Agency. Earthquake Hazards Reduction Series 31.

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A Methodology for Assessing the Risk of

Hazardous Materials Release Following Earthquakes - A Demonstration Study for the Los Angeles Area

1 .

2

Hope A. Seligson , Ronald T. I^guchi , and

Kathleen J. Tierney

1. Project Manager, Dames & Moore, Los Angeles, CA

2. Associate, Dames & Moore, Los Angeles, CA

3. Director of Research, Disaster Research Center,

University of Delaware

ABSTRACT

A methodology for estimating the risk of earthquakeinduced hazardous materials releases was developed for

the National Science Foundation and the National Center

for Earthquake Engineering Research. Seismic hazard

analyses, fragility modeling for facilities handling

hazardous materials and data on airborne materials

releases were used in the development of the methodology.

The risk was estimated in terms of population within the

study area exposed to hazardous materials as a result of

a postulated earthquake event. The procedure was

developed to be used as a tool by communities interested

in regional hazard management.

In order to demonstrate the methodology, Los Angeles

County was selected as a study area. Population data was

integrated into the methodology to predict the population

exposure to hazardous materials releases for three

earthquake scenarios: a Magnitude 8+ event on the San

Andreas fault, a Magnitude 7 event on the NewportInglewood fault, and a Magnitude 5.9 simulation of the

1987 Whittier Narrows earthquake.

437
INTRODUCTION

Exposure to hazardous materials as a result of an

earthquake-induced materials release is a threat to the

population in the immediate vicinity of any storage,

handling and processing facilities, as well as to the

surrounding communities. Although there has never been

a major incident involving hazardous materials in a U.S.

earthquake, smaller releases have occurred in events that

were moderate in size. In the 1989 Loma Prieta

earthquake, numerous minor releases were reported,

including a leak of at least 5000 pounds of anhydrous

ammonia from a food processing plant in Watsonville

(ABAC, 1990)

.

Responding to an earthquake-induced hazardous materials

release presents challenges not faced in other hazardous

materials emergencies. Following a major earthquake

event, heavy demands are likely to be made on community

emergency response capabilities and resources, making it

difficult to effectively deal with secondary emergencies

such as hazardous materials releases and fires.

Problematic tasks associated with response to a hazardous

materials release, including warning the public and

evacuating hazardous areas, would be much more difficult

following a major earthquake. Further, resource problems

will be compounded by possible simultaneous hazardous

materials release.

While awareness of the risk is growing, there has been

little research to date on the seismic sources of

hazardous materials releases, and seismic vulnerability

models for chemical facilities are almost nonexistent.

The research for this project combines seismic hazard

analyses, findings from research on earthquake-related

failures in industrial facilities, and data on airborne

toxic releases to develop a general methodology that

would enable local jurisdictions to determine the

magnitude of the problem in their community and identify

areas that are susceptible to exposure due to

earthquake-generated releases. This paper demonstrates

the application of this methodology to the Los Angeles

County area.

METHODOLOGY

The methodology developed for this project is diagrammed

in Figure 1 and discussed more fully in Tierney et al..

438
1991. Its application in this demonstration study may be

summarized as follows:

Hazardous Material Inventory

Hazardous materials number in the thousands, and new

products are constantly being developed. Before a

systematic analysis can be undertaken, it is necessary

to determine which hazardous substances are likely to

pose the biggest threat to the community in an

earthquake. For this demonstration, we have chosen to

focus on two hazardous materials; chlorine and ammonia.

These substances were selected because: (1) they are

responsible for the majority of fatalities and casualties

in U.S. hazardous materials incidents; (2) they are

present in large quantities in the study area. Greater

Los Angeles; and (3) they form clouds that can spread to

adjacent areas, thus presenting a hazard beyond the plant

gates

The facilities assumed to be possible sources of

hazardous materials in this study are twenty-two of the

largest users of chlorine and anhydrous ammonia in the

greater Los Angeles area. These users include petroleum

refineries, chemical manufacturers, and wastewater

treatment plants. Although the methodology as developed

calls for data obtained from inventories prepared under

state and federal laws, data on the subject facilities

were actually obtained from a survey conducted by the

South Coast Air Quality Management District.

These facilities, dispersed throughout the study area,

store and use varying amounts of chemicals. Facilities

have been categorized into three facility types based on

chemical usage patterns: chlorine storage facilities,

ammonia storage facilities, and ammonia processing

facilities. Chlorine storage amounts range from 4 to

1000 tons, while ammonia storage varies from 2 to

206 tons.

Earthquake Scenarios and Ground Shaking Estimates

Seismic hazard estimates have been developed for three

different earthquake scenarios. In this demonstration,

strong ground shaking was the only hazard considered,

although additional hazard estimates could be developed

for other earthquake effects, such as fault rupture,

liquefaction and other ground failures.

439
Scenario 1 is a Magnitude 7.0 event on the NewportInglewood fault. This fault was the source of the 1933

Long Beach earthquake (M 6.3), which caused 120 deaths

and $41 million (1933 dollars) in damage. A major

earthquake on the Newport-Inglewood Fault would likely

result in numerous fatalities and injuries, billions of

dollars in damages, and severe disruption of economic

activity at the local, regional, state and even national

levels

.

Scenario 2 is a Magnitude 8.3 earthquake on the San

Andreas fault. This event involves 300 km of fault

rupture along the Mojave, San Bernardino Mountains, and

Coachella Valley segments of the fault. Such an event

would be expected to cause high ground shaking levels

throughout the Los Angeles Basin. As with the

Newport-Inglewood event, losses and disruption would be

significant.

Scenario 3 is a Magnitude 5.9 simulation of the 1987

Whittier Narrows Earthquake. This earthquake, with

localized strong ground shaking, caused few deaths and

injuries, but produced losses exceeding $350 million. In

addition, the earthquake caused a significant hazardous

materials incident. A tank in the City of Santa Fe

Springs ruptured and leaked 240 gallons of chlorine into

the air. The resulting plume, which drifted through the

industrial section of the city toward Whittier, prompted

evacuation of some areas (FEMA, 1987).

Ground shaking intensities at each facility were computed

for each of the three earthquake scenarios, as follows.

Peak ground accelerations (PGAs) were calculated at each

location using a deterministic magnitude-distance

attenuation relationship. Calculated PGAs were then

converted to values of ground shaking intensity based on

the Modified Mercalli Intensity (MI^I) scale. These

conversions yield MMI values equivalent to PGA values for

sites located on "basement rock". These MMI values were

then modified to account for variations in local ground

conditions from "basement rock". Figure 2 shows the

resulting seismic hazard map for Scenario 1 and indicates

the locations of the 22 hazardous materials sources.

Chemical Facilities Modeling

Two "generic" facility models, a "generic" chemical

processing facility and a "generic" storage and transfer

facility, were developed for reasons of economy and

efficiency. It was assumed that facilities that perform

440
the same function have more or less the same components,

allowing for analysis by generalized facility type,

rather than on an individual facility basis. This

assumption is particularly applicable to the Los Angeles

area, where the range of chemical facilities types is

somewhat limited. Facilities are generally comprised of

the same components and follow similar process

operations, using gaseous toxic chemicals as reactants in

the manufacturing process.

Components of the chemical processing facility model that

are subject to failure include the: (1) pressurized

storage vessel; (2) exothermic reactor; (3) piping; and

(4) separator/regenerator. The storage and transfer

facility model is simply a subset of the processing

model, consisting of a storage vessel and associated

piping.

Facility Vulnerability Assessment

In analyzing complex systems, such as chemical

facilities, it is not possible to identify just one or

two failure modes that lead to overall system failure.

Instead, all conceivable failure modes must be

identified, and their individual contributions to overall

facility failure must be systematically combined. Fault

tree analysis is useful for this kind of assessment. In

fault tree analysis, boolean techniques are used to model

the interdependency of individual component failures.

Cases where several failure modes must occur for some

"fault" to occur are modeled using "AND gates." Cases

where some "fault" can occur due to one or more failure

modes are modeled using "OR gates". For this study,

fault tree models were developed for earthquake-generated

failures and toxic releases for chemical processing

facilities, and storage and transfer facilities. The

development of these fault tree models and the resultant

failure curves for each facility type is discussed in

detail in Tierney et al. (1991).

Plume Modeling

A chemical dispersion analysis was performed to estimate

the size and shape of the area exposed to anhydrous

ammonia (NH3) or chlorine gas (Clj) following an

earthquake-induced hazardous materials release. The

dispersion of the resulting hazardous materials clouds

441
was modelled using the SLAB dispersion model (Ermak,

1989) , for various meteorological conditions typical of

the Southern California Air Basin. The results of this

analysis yield a conservative estimate of the zone of

vulnerability, or area in which specific health criteria

may be exceeded, for a given release and meteorological

condition.

In order to determine potential zones of vulnerability,

it was necessary to establish health criteria for both

CI2 and NH3. The chemical-specific health criteria used

were based on the Emergency Response Planning Guidelines

(ERPGs) developed by a committee of the American

Industrial Hygiene Association (AIHA) . The criteria

selected for this study was ERFG 3, "the maximum airborne

concentration below which it is believed that nearly all

individuals could be exposed for up to one hour without

experiencing or developing life-threatening health

effects." This exposure level is 20 ppm for Chlorine and

1000 ppm for Ammonia.

For each meteorological condition and mode of chemical

release, a zone of vulnerability or hazard footprint was

determined. As a conservative estimate, the composite

maximum width and length were taken to represent a

generalized footprint for each release mode (i.e., the

largest width and length from all meteorological

conditions are used to define the exposure area for each

release mode)

.

Because it would be virtually impossible to account for

all of the variables that influence the position of the

hazardous materials plume, such as wind speed and

direction, a probabilistic approach was used to determine

the likelihood that a given site will be within a

hazardous material plume. Although hazard footprints are

sometimes irregular, varying from tear-drop shape to

circular, hazardous materials plumes were modelled as

ellipses. This general model was deemed appropriate

because it captured most of the characteristics of the

irregular footprints.

A mathematical derivation yields the probability of a

given site being located within a plume of given

dimensions. Given an elliptical plume pattern, the plume

must exist somewhere within a circle defined by sweeping

the ellipse (fixed at the source) through a 360 degree

arc. The plume's exact position within this circle is

unknown. Only sites within this circle can be exposed to

the chemical plume.

442
If one draws a circle with the center at the source, and

the radius equal to the distance from the source to the

site, the site will be within the plume if it sits

anywhere along the arc defined by the intersection of

this circle and the plume. Since the width of the plume,

and hence the length of this arc, varies with the

distance from the source, the probability of the site

being located within the plume varies with distance from

the source. Hence, this probability will depend on three

factors; the parameters that define the plume (semi-axes

a and b) , and the distance, d, from the site to the

source of the plume.

The probability, P, that the site will be located along

the arc located within the plume is the ratio of the arc

length, S, to the circumference of the circle whose

radius is equal to the distance from the source to the

^ S IBd e site: ^"^T^^z,—

C 2na 71 where Theta, measured in radians, represents the angle

between the plume axis and a line connecting the source

to the site.

Population Data

1980 census data was obtained for all enumeration

districts in the five county Los Angeles Basin area; Los

Angeles, Orange, Riverside, San Bernardino, and Ventura

Counties. In these five counties, a total of 10,370

enumeration districts represent 11.5 million people. For

each enumeration district, the population count is

associated with a representative geographic point

location.

COMPUTER MODELLING

A computer program was developed to determine the overall

risk of exposure, from aggregated information collected

during the first six steps of the risk assessment

methodology. Program "Plume" was designed to take the

collected data as input, and output the number of people

exposed to hazardous chemicals in a given earthquake

event

A probabilistic approach was used to develop Program

"Plume". The general procedure used to calculate

443
population exposure at a given site from a given

hazardous materials source, for a given earthquake event

is as follows:

1) Based on the ground shaking intensity (MMI) at the

hazardous materials source, calculate the

probability of failure in each failure mode for

each facility component. Also note the resultant

plume size if failure occurs in each component.

2) For each population center, calculate the distance

from hazardous materials source to the population

site.

3) For each component at the source facility, check

whether the population site could be located within

the resultant plume if failure occurs.

4) If the population site is within the plume's

extent, calculate the probability that the plume

will form over the site.

5) Aggregate these probabilities for all components at

the source to find the total probability of

exposure at the population site for release at this

source.

These values may be aggregated such that the total

exposure of each site from all sources is produced. In

our example, the exposure is further aggregated to the

County level.

RESULTS

The computer analysis yielded the number of people

exposed to hazardous materials in each of the five

counties, as a result of each scenario earthquake. Only

Los Angeles and Orange Counties were found to be affected

by possible hazardous materials releases from the listed

22 sources within Los Angeles County. As a result of a Magnitude 7.0 earthquake on the Newport-Inglewood fault,

133,000 people in Los Angeles and Orange Counties would

be exposed to hazardous materials released from the 22

subject sources. (1.8% of the population in Los Angeles

County, and 0.03% of the people in Orange County) . These

133,000 people are dispersed throughout more than 3000

enumeration districts. Of these 3000 enumeration

districts, only 1% have more than 500 people affected,

90% have fewer than 100 people affected, and 40% have

444
fewer than 10 people affected. The maximum number of

people exposed at any one site is approximately 1400.

From these same sources, a total of 2 0,7 63 people would

suffer exposure to hazardous materials following a M 8.3

event on the San Andreas fault. (0.3% of the population

in Los Angeles County, and 0.01% of those in Orange

County) . The stricken population would be distributed

among 2,850 enumeration districts. Of these districts,

99.9% would have fewer than 100 people affected, and

81.5% would have fewer than 10 people affected. The most

affected at one site would be only 211 people.

From the smallest of the three events, the WhittierNarrows simulation, only 6660 people (0.09% of the people

in Los Angeles County, and less than 0.01% in Orange

County) would be affected by the hazardous materials

release. 1800 enumeration districts would be affected;

99.7% of these would have fewer than 25 people affected,

and 75% would have fewer than 5 people affected. The

largest number of people affected by the release in any

one enumeration district is 57 people.

For the event presenting the greatest threat to

population, the Newport-Inglewood event, the locations of

the 20 enumeration districts with the greatest number of

people affected by hazardous releases have been

identified, and are plotted in relation to the potential

sources in Figure 3. Each of these districts has more

than 500 people affected, and the total number of people

affected within these districts comprises 12% of the

overall number of people affected by hazardous releases

in this event.

CONCLUSIONS

The threat of hazardous materials release exists wherever

hazardous materials are stored. Earthquake-induced

releases are a very real possibility. Based on the

22 sources identified for this study, the most serious

releases would occur not in the largest postulated

earthquake, but in the earthquake causing the strongest

ground shaking at the hazardous materials sources. This

earthquake, the Magnitude 7.0 Newport-Inglewood event,

would cause ground shaking of at least intensity VIII at

all but two of the studied sources. In contrast, the

M 8.3 San Andreas event causes MMI VIII or more at only

4 sites. This type of information would be useful in the

planning efforts of local communities. If a community

could identify those facilities likely to be in areas of

445
strong ground shaking in postulated earthquakes

representative of the local seismic hazard, they could

concentrate mitigative efforts on these facilities.

One of the most serious hazardous materials threats is

presented by the storage of large quantities of chlorine

in areas expected to suffer strong ground shaking.

Chlorine is stored in vessels as large as 90-ton rail

cars, whose failure plumes can extend over 7 miles. The

identification of chlorine as the more serious threat

enables users to address this risk by concentrating

efforts in improving performance of existing vessels,

developing smaller safer vessels, or perhaps relocating

storage facilities.

The failure models developed for use in this study are

based on conservative assumptions regarding failure

thresholds. Even with these conservative assumptions,

the largest total expected population affected in any of

the three scenarios is 132,000 or less than 2 percent of

the total population of Los Angeles County. These

estimates, however, do not include risks that may result

from failure of chemical facilities in counties other

than Los Angeles, or from chemicals other than ammonia or

chlorine. A more complete analysis of risk must include

these other facilities and chemicals.

FUTURE DIRECTIONS IN RESEARCH AND APPLICATION

There are various types of research that would make this

methodology more widely applicable. Some are widely

explored, such as improved seismic hazard assessments,

while others are specific to this type of analysis.

Possibilities for this type of research include

developing an extensive library of plume patterns for a

wide variety of hazardous chemicals, and developing

additional chemical facility models and failure curves.

To further explore the benefits to the planning efforts

of a local jurisdiction, the completion of a smaller

scale, detailed risk assessment including a more

extensive inventory of chemicals and sources, tied to the

development of detailed response and evacuation plans,

would be the next logical step in the development of this

methodology.

446
ACKNOWLEDGMENTS

The authors wish to acknowledge the support of the

National Science Foundation and the National Center for

Earthquake Engineering Research for this project.

Specifically, we would like to thank Dr. William Anderson

of NSF and Drs. Barclay Jones and Masanobu Shinozuka of

NCEER. The authors would also like to thank Mr. Ken

Richmond of TRC Environmental Consultants for his help in

performing the air dispersion analysis, and Mr. Robert A.

Antonoplis of Sidley and Austin, Los Angeles, for his

support in developing the generic chemical facility

models

REFERENCES

ABAC, 1990. "Database of Hazardous Materials Releases

Which Have Occurred Due to Earthquakes", Association of

Bay Area Governments, Oakland, California.

EPA, 1988. "Screening Procedures for Estimating the Air

Quality Impacts of Stationary Sources", U.S. EPA, Office

of Air Quality Planning and Standards, North Carolina,

EPA-450/ 2 -4-88-010.

Ermak, D.L., 1989. "User's Manual for SLAB: An

Atmospheric Dispersion Model for Denser-Than-Air

Releases", Atmospheric and Geophysical Sciences

Division, Lawrence Livermore National Laboratory,

Livermore, California.

FEMA, 1987. "The Los Angeles - Whittier Narrows

Earthquake of October 1, 1987: Federal/State Hazard

Mitigation Survey Team Report", Prepared by the Federal

Emergency Management Agency, Region IX; California

Governor's Office of Emergency Services, Southern

California Earthquake Preparedness Project and Planning

Division.

Tierney, K.J, H.A. Seligson, R.T. Eguchi, and K.

Richmond, 1991. A Methodology for Estimating the Risk of

Post-Earthquake Hazardous Materials Release . Prepared for

the National Science Foundation and the National Center

for Earthquake Engineering Research.

447
Figure 1 . Methodology for Risk Assessment of

Hazardous Materials Release During Earthquake

448
and Ammonia storage

2 Chlorine Processing

5 Chlorine Processing

3 Chlorine Storage and and Ammonia Storage

Ammonia Processing

6 Ammonia Storage

0 4^5 9^0 SCALE IN MILES

Figure 2. Seismic Hazard Map (Modified Mercalli Intensity) for a

Magnitude 7.0 Eartliqual<e on the Newport-lnglewood Fault

with Site Locations

449
450

Dames & Moore
VIII. WORKSHOP RESOLUTION

451

RESOLUTIONS OF THE

FOURTH U.S.-JAPAN WORKSHOP ON

EARTHQUAKE DISASTER PREVENTION FOR LIFELINE SYSTEMS

Biltmore Hotel, Los Angeles, California

August 1 9-21 , 1 991

The Fourth U.S.-Japan Workshop on Earthquake Disaster Prevention for Lifeline

Systems was held under the sponsorship of the Public Works Research Institute of

Japan and the U.S. National Science Foundation under the auspices of Task

Committee F, "Disaster Prevention Methods for Lifeline Systems," UJNR Panel on

Wind and Seismic Effects at the Biltmore Hotel, Los Angeles, California, United States

on August 19-21, 1991.

The workshop provided a valuable forum to exchange information and ideas on

technical and socioeconomic issues important to the lifeline earthquake engineering

communities of both countries. The following topics were addressed:

a. Soil Effects

b. Seismic Design and Analysis: Transportation

c. Seismic Design and Analysis: Pipelines and Tunnels

d. Seismic Risk Analysis

e. Post-Earthquake Response/Damage Detection

f. Socioeconomic Impacts

g. Future Directions for Research Application and Design.

The workshop identified, without priority order, the following topics relevant to lifeline systems for further cooperative research programs:

a. Effects of Soils on Lifeline Components;

b. Prioritization Procedures for the Seismic Inspection and Retrofit of Lifeline

Structures;

0. Use of Passive, Active, and Hybrid Control Techniques for Improving the

Seismic Safety and Performance of Lifeline Structures;

d. Dynamic Response and Design of Lifeline Structures;

e. System Reliability Methods for Lifeline Systems;

f. Repair and Rehabilitation of Lifeline Systems;

g. Post-Earthquake Performance and Restoration of Lifeline Systems;

453
h. Post-Earthquake Damage Detection Procedures;

i. Socio-Economic and Environmental Impacts of Lifeline System Failures;

j. Emergency and Disaster Response Management of Lifeline Systems;

k. Information Dissemination on the Development of Seismic Performance

Standards for Lifelines, Particularly Telecommunication Systems;

I. Use of Innovative Materials, Advanced Sensors and Intelligent Control Systems

for Lifeline System Operations, Emergency Control, Damage Isolation,

Replacement and Restoration;

m. Collection of Data (e.g., strong-motion response, laboratory testing and

earthquake damage data) to Verify Methodologies and Models Used in Lifeline

Earthquake Engineering; and

n. Lifeline Interaction Concerns, i.e.. Dependency on Other Lifeline Services.

4. The workshop acknowledges current efforts in both countries to establish seismic

design guidelines and standards for lifeline systems. Encouragement in the actual

development of such standards should be placed on the U.S. effort. Existing UJNR

channels should be fully utilized to facilitate the exchange of relevant technical

information concerning standards development. Possible collaboration of joint

development of lifeline system standards and guidelines should be pursued.

5. The importance of the "International Decade for Natural Disaster Reduction" (IDNDR)

in its relation to lifeline earthquake engineering and disaster mitigation research under

the UJNR program continues to be emphasized. Future joint activities between both

countries in the area of earthquake disaster prevention for lifeline systems shall

consider their contribution to the achievement of the goals of the IDNDR program.

These future activities shall be defined by the Co-Chairmen of Task Committee "F" of

the UJNR Panel on Wind and Seismic Effects.

6. The workshop recognizes the importance to continue exchange of research

personnel, technical information, research data and use of available research facilities

in both countries. The workshop further recognizes the benefit of identifying specific

activities to compare the results of different design, analysis and experimental

methods, and disaster mitigation strategies of both countries.

7. In view of the importance of cooperative research programs on seismic effects and

earthquake disaster prevention methods on lifeline systems, it is recommended to

hold the 5th Workshop in late 1 992 in Japan. The location and time of the workshop

will be determined through correspondence between the Co-chairmen of Task

Committee "F" of the UJNR Panel on Wind and Seismic Effects.

454
IX. APPENDICES

WORKSHOP PROGRAM

WORKSHOP PARTICIPANTS

PHOTOS

455

FOURTH U.S. - JAPAN WORKSHOP ON

EARTHQUAKE DISASTER PREVENTION FOR LIFELINE SYSTEMS

AUGUST 19 - 21, 1991

BILTMORE HOTEL

LOS ANGELES, CALIFORNIA

WORKSHOP PROGRAM

MONDAY, AUGUST 19, 1991

8:30 a.m. - Registration - Heinsbergen Room

9:00 a.m. - Session 1 - Opening Session

Welcoming Remarks by Mr. R.T. Eguchi

Dames & Moore

Address by Dr. S.C. Liu

National Science Foundation

Address by Dr. Y. Sasaki, Director

Earthquake Disaster Prevention Department, PWRI

Address by Mr. R. Dikkers

Group Leader, Structural Evaluation, NIST

9:30 a.m. - Session 2 - Soil Effects

(Chairmen: J. Cooper, E. Kuribayashi)

9:30 U-1 "Performance of Water Supply Pipelines in Liquefied Soil"

(K. Porter, C. Scawthorn, M. Khater, T. O'Rourke)

9:45 J-1 "A Proposal of Practical Earthquake Response Analysis Method 6

Cylindrical Tunnels in Soft Ground"

(Y. Shiba, S. Okamoto)

10:00 J-2 "Visual Information System for Seismic Ground Hazard Zoning"

(K. Tokida, H. Matsumoto, Y. Sasaki)

457
10:15 Discussion

10:30 a.m. - Break

10:45 a.m. - Session 3 - Seismic Design and Analysis: Transportation

(Chairmen: H.S. Lew, T. Sato)

10:45 U-2 "Seismic Risk Identification and Prioritization in the

CALTRANS Seismic Retrofit Program"

(B. Maroney, J. Gates)

11:00 U-3 "An Old Bridge gets a Seismic Facelift"

(G. Snyder, E. Lindvall, R. Lyons)

11:15 J-3 " Seismic Inspection and Seismic Strengthening of Highway Bridges

in Japan"

(K. Kawashima, S. Unjoh, H. lida)

11:30 Discussion

12:00 p.m. - Lunch - Corinthian Room

1:00 p.m - Group Photo

1:30 p.m. - Session 4 - Seismic Design & Analysis: Pipelines & Tunnels

(Chairmen: T. Lew, N. Nishio)

1:30 U-4 "Repair and Rehabilitation of Buried Water and Sewer Lifelines"

(L. Wang, H. Kennedy)

1:45 J-4 "Investigations on External Force Evaluation in the Seismic

Deformation Method"

(N. Takahashi, M. Takeuchi, K. Irokawa)

2:00 U-5 "Estimation of System Reliability for Lifeline Standards and

Example Using the City of Everett, Washington Lifelines"

(D. Ballantyne)

2:15 J-5 "Dynamic Response of Twin Circular Tunnels during

Earthquakes"

(T. Okumura, N. Takewaki, K. Shimizu, K. Fukutake)

2:30 Discussion

458
2:45 p.m. - Break

3:00 p.m. - Session 5 - Seismic Design & Analysis: Pipelines & Tunnels

(Chairmen: M. Celebi, M. Nakamura)

3:00 U-6 "Data Base of Pipeline Failures, Loma Prieta Earthquake,

October 17, 1989"

(L. Lund)

3:15 J-6 "Behavior of Flat Underground Structures during Earthquakes

and Seismic Loads Acting on Them"

(S. Mori, T. Ikeda, K. Matsushima, H. Tachibana)

3:30 J-7 "Seismic Response of Super-Deep Vertical Shaft with Circular

Cross-Section"

(N. Ohbo, K. Hayashi, K. Ueno)

3:45 J-8 "Seismic Design Method of Shield Tunnels with Axial Prestressing

by Means of Rubber and PC Bar"

(K. Matsubara, K. Urano)

4:00 J-9 "Seismic Isolation for Underground Structures"

(K. Ono, S. Shimamura, H. Kasai)

4:15 Discussion

5:00 p.m. - Adjourn

6:30 p.m. - Reception at the Biltmore Hotel - Imperial Suite

7:30 p.m. - U.S. Hosted Dinner - Imperial Suite

TUESDAY, AUGUST 20, 1991

8:30 a.m. - Session 6 - Seismic Risk Analysis

(Chairmen: H. Andress, N. Ohbo)

8:30 U-7 "Performance of AWSS of San Francisco During and After Loma

Prieta Earthquake"

(M. Khater, C. Scawthorn, T.D. O'Rourke, F. Blackburn)

459
8:45 J-10 "Seismic Reliability Analyses of Large Scale Lifeline Networks

Taking into Account the Failure Probability of the Components"

(T. Sato, K. Toki)

9:00 J-11 "Earthquake Damage Analysis on Telecommunication Conduits"

(K. Yagi. S. Mataki, N. Suzuki)

9:15 U-8 "Regional Risk Assessment of Environmental Contamination from

Oil Pipelines"

(S. Pelmulder, R. Eguchi)

9:30 Discussion

9:45 a.m. - Break

10:00 a.m. - Session 7 - Post-Earthquake Response/Damage Detection

(Chairmen: H. Lagorio, S. Mataki)

10:00 J- 12 "Data Acquisition and Emergency Response System for City Gas

Pipeline Operation during a Major Earthquake"

(Y. Yoshikawa)

10:15 J-13 "Damage Inspection Systems Immediately after an Earthquake"

(K. Kawashima, H. Sugita, K. Kanoh)

10:30 J-14 "Estimation of Degree of Anxiety Felt by People in Underground

Urban Spaces During Earthquakes"

(E. Saito, H. Ikemi, H. Nakano, M. Nakamura)

10:45 U-9 "Performance of Lifelines and Emergency Response in Watsonville,

California to Loma Prieta Earthquake"

(J. Isenberg)

1 1 :00 U- 10 "Strategies for Repair and Restoration of Seismically Damaged Gas

Pipeline Systems"

(M. Shinozuka)

11:15 Discussion

12:00 p.m - Lunch - Corinthian Room

460
1:00 p.m. - Session 8 - Socioeconomic Impacts

(Chairmen: J. Gates, E. Saito)

1:00 J- 15 "Lifeline Earthquake Hazard Zonation in Socio-economic Aspects"

(E. Kuribayashi)

1:15 U-11 "Organizational Features of U.S. Lifeline Systems and their

Relevance for Disaster Management"

(K. Tierney)

1:30 U-12 "A Methodology for Assessing the Risk of Hazardous Materials

Release Following Earthquakes - A Demonstration Study for the

Los Angeles Area"

(H. Seligson, R. Eguchi, K. Tierney)

1:45 U-13 "Recent Advances in Seismic Design and Retrofit of California

Bridges"

(J. Roberts)

2:00 Discussion

2:15 p.m. - Break

2:30 p.m. - Session 9 - Future Directions for Research Application and Design

(Chairmen: R. Eguchi, K. Kawashima)

2:30 J- 16 Japan Perspective

(Y. Sasaki)

3:00 U-14 U.S. Perspective

(R. Dikkers)

3:30 p.m. - Break

4:00 p.m. - Adoption of Resolutions

5:15 p.m. - Closure

5:30 p.m. - Adjourn

7:00 p.m. - Japan Side Hosted Dinner - The Castaways

(Bus leaves in front of Biltmore Hotel at 6:30 p.m.)

WEDNESDAY, AUGUST 21, 1991

461
8:30 a.m. Bus arrives at Biltmore for start of Field Trip. All who are going onto the ASCE

Conference should be downstairs with their luggage at this time.

9:00 a.m. Bus leaves.

9:30 a.m. - Tour of the Ralphs Grocery Company Automated Warehouse

11:00 a.m

11:15 - Tour of the Retrofitted Bridge Structure of the 134 and 2 Freeways

11:45

12:00 - Lunch at the Odyssey Restaurant

l:p.m.

1:30 p.m. - Tour of the Jensen Filtration Plant

3:30 p.m.

4:15 p.m. Tour of the Retrofitted Bridge Structure of the 405 and 10 Freeways (if time

allows)

5:00 p.m. Bus drops ASCE participants at Holiday Inn Brentwood/Bel Air

5:45 p.m. Bus stops at the Miyako Hotel

6:00 p.m. Bus returns to the Biltmore Hotel

462
PARTICIPANTS FOR THE 4TH U.S.-JAPAN WORKSHOP

ON LIFELINE EARTHQUAKE ENGINEERING

(FROM JAPAN SIDE)

Tsuneo Katayama

Director

International Center for Disaster

Mitigation Engineering

Institute of Industrial Science

University of Tokyo

7-22-1 Roppongi, Minato-ku,

Tokyo 106, Japan

Hiroshi Kasai

Chief

Civil Engineering Department

Konoike Construction Co., Ltd. 3-6-1, Kitakyuhoji-Machi, Chuo-ku,

Osaka 541 , Japan

Kazuhiko Kawashima

Head, Earthquake Engineering Division

Earthquake Disaster Prevention Department

Public Works Research Institute Ministry of Construction

Tsukuba, 305 Japan

Elichi Kuribayashi

Professor

Department of Construction

Toyoshashi University of Technology

Toyohashi, 440, Japan

Shinji Mataki

Head, Disaster Prevention Facility Division

Civil Engineering Project Group

Tsukuba Field Technical Development Center

NTT

Tsukuba, 305 Japan

KatsumI Matsubara

Assistant Manager

Technical Research Institute Hazama Corporation

4- 17-23, HonmachI Nishi, Yono, Saitama,

338, Japan

Akio Matsuura

Research Engineer

Research Department

Advanced Construction Technology Center

2-10-2, Otowa, Bunkyo-ku, Tokyo 112

Japan

Masahiro Nakamura

Leader, Concrete Group

Department of Civil Engineering

Technical Research Institute Fujita Corporation

74 Ohdana-cho, Kohoku-ku,

Yokohama 223, Japan

Nobuaki Nishio

Senior Researcher

Fundamental Technical Research Laboratory

Tokyo Gas Co., Ltd. Minato-ku, Tokyo, Japan 105

Naoto Ohbo

Senior Research Engineer

Kajima Institute of Construction Technology

Kajima Corporation

19-1, Tobitakyu 2-Chome, Chofu-shi,

Tokyo 182, Japan

Susumu Okamoto

Research Engineer

Earthquake Engineering Team

Earthquake and Wind Engineering Group

Technology Research Center

Taisei Corporation

344-1 , Nasematchi, Totuka-ku,

Yokohama 245, Japan

Toshihiko Okumura

Research Engineer

Ohsaki Research Institute Shimizu Corporation

2-2-2, Uchisaiwai-cho,

Chiyoda-ku, Tokyo 100, Japan

Etsuro Saito

Senior Research Engineer

Department of Civil Engineering

Technical Research Institute Fujita Corporation

74 Ohdana-cho, Kohoku-ku,

Yokohama 223, Japan

Yasushi Sasaki

Director

Earthquake Disaster Prevention Department

Public Works Research Institute Ministry of Construction

Tsukuba Science City, Ibaraki-ken,

304, Japan

463
Tadanobu Sato

Associate Professor

Urban Earthquake Hazard Research Center

Disaster Prevention Research Institute Kyoto University

Kyoto 611, Japan

Sadao Shimamura

Manager

Civil Engineering Department

Konoike Construction Corporation

3-6-1 , Kitakyuhoji-Machi,

Chuo-ku, Osaka 541 , Japan

Taketoshi Shimoda

Underground Facility Department

Tokyo Plant Engineering Center

NTT

1-9-2 Yokozuna, Sumida-ku, Tokyo

Japan 130

Naoki Takahashi

Assistant Manager

Tokyo Branch

Civil Engineering Division

Okumura Corporation

7-2-16, Nishikasai, Edogawa-ku, Tokyo

134, Japan

Hideo Tachibana

Manager

Research and Development Department

Technology Development Division

Tobishima Corporation

757 Futako, Tamatsu-ku, Kawasaki-city,

Kanagawa 213, Japan

Yoichi Yoshikawa

Senior Manager

Center for Disaster Management and Supply Control

Tokyo Gas Co. Ltd. Minato-ku, Tokyo 105 Japan

ac:\rlsk\rte\agencia1.819
PARTICIPANTS FOR THE 4TH U.S.-JAPAN WORKSHOP

ON LIFELINE EARTHQUAKE ENGINEERING

(FROM U.S. SIDE)

Harold (Bud) Andress

Federal Emergency Management Agency

500 C Street, S.W.

Washington, D.C. 20472

Donald Ballantyne

Senior Sanitary Engineer

Kennedy/Jenks/Chilton

530 South 336th Street Federal Way, WA 98003

Mehmet Celebi

Research Civil Engineer

U.S. Geological Survey

345 Middlefield Road, MS 977

Menio Park, CA 94025

James Cooper

Deputy Chief, Structural Division

Federal Highway Administration

6300 Georgetown Pike

McLean, VA 22101

Robert D. Dikkers

Group Leader

Structural Evaluation

Building and Fire Laboratory

National Institute of Standards & Technology

U.S. Department of Commerce

Gaithersburg, MD 20899

Ronald T. Eguchi

(Group Leader)

Earthquake Risk Assessment

Dames & Moore

91 1 Wilshire Boulevard, Suite 700

Los Angeles, CA 90017

James Gates

Super. Bridge Engineer

Division of Structures Department of Transportation

State of California P.O. Box 942874

Sacramento, CA 94274-0001

Jeremy Isenberg

Principal

Weidlinger Associates

4410 El Camino Real, Suite 110

Los Altos, CA 94022

Mahmoud Khater

Senior Research Engineer

EQE Engineering

595 Market Street 18th Floor

San Francisco, CA 94105

Henry Lagorio

Earthquake Hazard Mitigation Project

National Science Foundation

1800 G Street N.W.,Room 1132

Washington D.C. 20037

H.S. Lew

National Institute of Standards & Technology

Chief, Structural Division

National Institute of Standards & Technology

Center for Building Technology

Building 226, Room 168

Gaithersburg, MD 20899

Tingley K. Lew

Naval Civil Engineering Laboratory

Department of Navy

Port Hueneme, CA 93043-5003

S.C. Liu Program Director

Earthquake Hazard Mitigation

Division Civil/Environmental Engineer

National Science Foundation

1800 G Street, N.W.

Washington, D.C. 20550

Le Val Lund

Consultant

Civil Engineering

3245 Lowry Road

Los Angeles, CA 90027

i 465
Robert Lyons

Metropolitan Water District Leon R.L WangProfessor, Chairman

Department of Civil Engineering

Old Dominion University

Norfolk, VA 23529

of Southern California

1111 Sunset Boulevard

Los Angeles, CA 90054

Brian Maroney

Seismic and Structural Analysis

Division of Structures Department of Transportation

State of California

1801 30th Street Sacramento, CA 95816

James E. Roberts

Chief, Division of Structures Department of Transportation

State of California

1120 N. Street, Suite 511

Sacramento, CA 95807

Charles Scawthorn

Vice President

EQE Engineering

595 Market Street, 18th Floor

San Francisco, CA 94105

Hope Seligson

Dames & Moore

91 1 Wilshire Boulevard, Suite 700

Los Angeles, CA 90017

Masanobu Shinozuka

Director

National Center for Earthquake Engineering Research

Room 11 Red Jacket

State Univerlty of New York

Buffalo, NY 14261

Gary Snyder

Metropolitan Water District of Southern California

1111 Sunset Boulevard

Los Angeles, CA 90054

Kathleen Tierney

Research Director/Associate Professor

Disaster Research Center

University of Delaware

Newark, DE 19716

466
467



Photo 10

471


Photo 15
Photo 18

475



Photo 26

479



|lsT-li4A U.S. DEPARTMENT OF COMMERCE

'ev. 3-90) NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

BIBLIOGRAPHIC DATA SHEET

1. PUBLICATION OR REPORT NUMBER

NIST/SP-840

2. PERFORMINQ ORGANIZATION REPORT NUMBER

3. PUBUCATION DATE August 1992

TITLE AND SUBTITLE Proceedings of the 4th U.S. -Japan Workshop on Earthquake Disaster Prevention

'!or Lifeline Systems

AUTHOR(S)

lonald T. Eguchi, Editor

PERFORMINQ ORQANIZATION (IF JOINT OR OTHER THAN NIST, SEE INSTRUCTIONS)

Ronald T. Eguchi, Editor

Dames & Moore

, Los Angeles, CA 90017

7. CONTRACT/QRANT NUMBER

8. TYPE OF REPORT AND PERIOD COVERED

Final

[ SPONSORINQ ORQANIZATION NAME AND COMPLETE ADDRESS (STREET, CITY, STATE, ZIP) National Science Foundation Public Works Research Institute

Washington, DC 20550 Tsukuba, Japan

). SUPPLEMENTARY NOTES

Robert D. Dikkers, Publication Coordinator

Building and Fire Research Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899

h. ABSTRACT (A 200-WORD OR LESS FACTUAL SUMMARY OF MOST SIGNIFICANT INFORMATION. IF DOCUMENT INCLUDES A SIGNIFICANT BIBUOQRAPHY OR

UTERATURE SURVEY, MENTION IT HERE.)

These proceedings document the results of the Fourth U.S. -Japan Workshop on Earthquake

Disaster Prevention for Lifeline Systems held on August 19-21, 1992, in Los Angeles,

California. The theme of the workshop focused on "Future Directions for Research,

Application, and Design of Lifeline Systems." Technical topics discussed include:

effects of soils on lifeline components; seismic design and retrofit of lifeline

systems; dynamic response and analysis of lifeline systems; repair and rehabilitation

of lifeline systems; system reliability methods for lifeline systems; post-earthquake

damage detection procedures; socioeconomic and environmental impact of lifeline system

failure; and emergency and disaster response management of lifeline systems. Thirty

papers were presented in two days of plenary sessions; 16 papers from Japan and 14

papers from the U.S.

12. KEY WORDS (6 TO 12 ENTRIES; ALPHABETICAL ORDER; CAPITAUZE ONLY PROPER NAMES; AND SEPARATE KEY WORDS BY SEMICOLONS)

bridges; dynamic response and analysis; earthquake disaster prevention; lifeline facilities;

pipelines; repair and rehabilitation; seismic safety; tunnels; water and sewer

13. AVAILABIUTY UNUMITED

FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE TO NATIONAL TECHNICAL INFORMATION SERVICE (NTIS). XX

XX

XX

ORDER FROM SUPERINTENDENT OF DOCUMENTS, U.S. GOVERNMENT PRINTING OFFICE, WASHINGTON, DC 20402. ORDER FROM NATIONAL TECHNICAL INFORMATION SERVICE (NTIS), SPRINGFIELD, VA 22161.

14. NUMBER OF PRINTED PAGES

468

IS. PRICE

ELECTRONIC FORM * U.S. G.P.O. :1992-311-891 :60517

J

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