No. 41 April 2014

STEEL CONSTRUCTIONTODAY & TOMORROW

http://www.jisf.or.jp/en/activity/sctt/index.html【 n a m i 】“波 (nami)” in Japanese, or “wave” in English

Issue No. 41 is a special publication for the Japanese Society of
Steel Construction (JSSC). It includes a special feature on measuresdevised to handle huge tsunamis ( 津波 tsunami, or tidal wave).
Special Issue: Japanese Society of Steel Construction
Commendations for Outstanding Achievements in 2013
1 TOKYO SKYTREE 2 Closed High-rise Demolition Method

4 Compact Section Girder Bridge

Photo: Kenichi Ishii

3 Shibuya Hikarie

5 Effect of Deck Plate Thickness on Fatigue Durability;Displacement
Response Control Effect for Conventional Braces

6 Welded Moment Connections Strengthened by Thick Flange;
Method to Predict Steel Member Volume Loss Using FEM

Special Feature: Measures for Handling Giant Tsunamis

Published Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel Construction

7 Steel-structure Tsunami Countermeasures
9 Vertically Telescopic Breakwater

11 Flap Gate Tsunami Breakwater

13 Tsunami Evacuation Measures

14 Tsunami Evacuation Building

15 Building for Use as Tsunami Countermeasures
16 Structural Design Method for Tsunami Evacuation Buildings
17 JSSC Operations

Back Cover To Our Readers

Commendations for Outstanding Achievements in 2013-JSSC Prize

Design and Construction of TOKYOSKYTREE

Prize winners: Nikken Sekkei Ltd., Obayashi Corporation, JFE Steel Corporation, Kobe Steel, Ltd.,
Nippon Steel & Sumitomo Metal Corporation, Komaihaltec Inc., Kawada Industries Inc., Tomoe
Corporation and Nippon Steel & Sumikin Engineering Co., Ltd.
TOKYO SKYTREE® is a freestanding
broadcast tower that was constructed in
Sumida-ku, Tokyo, at the request of six Tokyo broadcasting companies. The tower rises
634 m into the sky and is the tallest structureof its kind in the world.
The structural concept upon which thetower is configured may be expressed with
two words: the “warping” of Japanese swords(katana) and the “camper” found in the columns of traditional Japanese architecture.
This concept is expressed three-dimensionally in the tower’s complex design that begins
as a regular triangle at the base and becomescircular at a height of 300 m.
In terms of the structural plan, two observatories are installed at heights of 350 m and
450 m, respectively; while at heights of 500

m and higher, the tower supports the broadcasting antenna of the various broadcastingstations.
Because of the tower’s extremely slender configuration (with a 9.3 width-to-heightratio imposed by the restrictions of the construction site), the foundation is worked uponby large press force and tensile force caused
by earthquakes and high-velocity winds. To
treat these forces and to ensure highly reliable and safe support for the tower, a continuous underground “knuckle wall” pile of steel
and reinforced-concrete was adopted. In order to give the tower a neatly shaped appearance with no gusset plates, a steel pipe truss
structure was adopted for the tower sectionthat uses high-strength, large-section steel
pipes joined by means of tubular joints.

Outline of Shimbashira Vibration-control System

Outline of TOKYO SKYTREE®
Completion: February 2012 (Sumidaku, Tokyo)
Project owner: Tobu Tower Skytree
Co., Ltd. and Tobu Railway Co., Ltd.
Design: Nikken Sekkei Ltd.
Construction: Obayashi Corporation
Ample countermeasures have been employed to handle earthquake and wind. Basedon field surveys, such as a wind velocity
survey of upper-level winds using a GPSmounted observation balloon and a microtremor survey of the construction site, simulated wave force waveforms and site waves
were prepared to verify the tower’s structural safety. To this end, the resulting structural safety is higher than that of other high-risebuildings commonly erected in Japan. As an
additional measure to deal with earthquakes,
the shimbashira vibration-control system(devised for the first time for this building)
was developed and deployed to mitigate seismic forces.
￭

Movable zone
Lock cylinderDamperSection of tower section

Steel Fixed zone
product

Drawing of pile foundation (looking-up drawing)

Section of base section
1 Steel Construction Today & Tomorrow April 2014

World’s tallest broadcast
tower-Performance Prize

Development of a Closed Demolition
Method for High-rise Buildings
Prize winner: Taisei Corporation

High-rise buildings are mostly located indense urban areas. In recent urban redevelopment, rebuilding of existing highrise buildings greater than 100 m in height
has increased, thereby making the proposed
methods of high-rise building demolition an
important element in the promotion of urban
redevelopment projects.
Given this trend, Taisei Corporation developed a demolition method called the“TECOREP (Taisei Ecological Reproduction) System” that mitigates the adverse effects of demolition work on the surrounding
environment, improves safety and reduces
the negative environmental impact of the demolition work. This system has been successfully used already in the demolition of a highrise office building with a height of 105 m
and a high-rise hotel building with a heightof 140 m.
A major feature of the TECOREP systemis the capped enclosure that is built by effectively using the existing structure of the topmost floors and carrying out the demolition
work within the enclosed space. Specifically, the building is demolished floor by floor
downwards, starting from the top. The enclosure in which the target floor is demolishedcan be safely and quickly translocated to thelower floor using hydraulic jacks installed on
temporary columns that support the capped
structure. Further, the new system incorporates power generation capabilities in thevertical transport system that is used to lower
the demolished materials etc. to the ground,
thereby leading to energy savings and reduced CO2 emissions.
The practical applicability of the
TECOREP system has been demonstrated byits use in the demolition of Japan’s tallest hotel building with a height of 140 m. Demoli-

The 140 m-high hotel building being demolished using the TECOREP systemtion work conducted in a closed
space mitigates neighborhood
anxiety and ensures safety; it allows shortening of the demolition period through a reductionin the number of lost work days.
The demolition system not only reduces noise levels (by 20
dB or more) but also prevents
the dispersion of dust and soot(by 90% or more). Moreover,in terms of securing workplacesafety, the implementation ofdemolition work in an enclosed
space yields many other advantages, although they cannot be
quantified numerically.
￭

Inner view from the floor center after
configuring the TECOREP system
Inner view of the TECOREP system

Jacking-down procedure during demolition using the TECOREP system
April 2014 Steel Construction Today & Tomorrow 2

-Performance Prize

Design and Construction of Shibuya
Hikarie

Prize winners: A Joint Venture (JV) of Nikken Sekkei Ltd. and Tokyu Architects & Engineers Inc. and a
JV of Tokyu Construction and Taisei Corporation
Shibuya Hikarie is positioned as one of theleading projects of the urban redevelopment
program for the area surrounding Shibuya
Station in Tokyo. It is a multipurpose highrise building with a height of about 185 m.
Its primary objective is to create new culturesand lifestyles by drawing together a multiplicity of dissimilar activities, such as commerce, recreation, culture and business.
A major task of the structural plan is thatthe building incorporates a theater with about
2,000 seats in the mid-story and that the design offer different configurations in thehigh- and low-rise sections.
In general, when different applications
are accommodated in a multi-layered structure, columns do not pass vertically throughthe building structure. As a result, a widely adopted solution for resisting a building’s
vertical and horizontal loads is to form large
trusses. In the current project, instead of acomplex-structured building in which offices, a theater and commercial facilities are arranged in a multi-layered form, a simple andclear structural plan was adopted to avoid
the structural issues associated with complex

structures.
Among the major devices adopted to realize such a highly reliable structural plan are
the following:• Because a theater with a wide, column-freespace is provided in the mid-story, the installation of columns that do not pass vertically through the building was held to a minimum (four columns).
• The adopted plan has four columns that risefrom the upper theater section and are supported by “Super-Beam” having a truss heightof two stories.
• On both sides of the theater, box-shaped concrete filled steel tubes (CFT) are arranged as
the main pillars, rising upwards through theheight of the building structure. Although themember sections of the Super-Beam becomelarge, and as a result the bending stress working on the columns increases, the CFT main
pillars having sufficiently high rigidity andstrength tolerate these stresses.
• The adoption of CFTs for the interior columns
reduces the shear force borne by the exterior
columns that are subjected to additional large
axial forces during an earthquake.
￭

Outline of Shibuya Hikarie
Completion: 2012 (Shibuya-ku, Tokyo)
Arch./Eng.: Nikken Sekkei Ltd.

Full view of Shibuya Hikarie

Outline of Structural Plan

Vibration-control
brace (LY225)
Office floor: 18th~34th stories

Vibration-control
brace (LY225)

Super-Beam floor: 17th story

Theater floor: 14th story
3 Steel Construction Today & Tomorrow April 2014

Seismic-resistant brace (SN400)

Lateral-direction
Longitudinal-direction
framing elevation (5)framing elevation (E)LegendVibration-control brace
Super-BeamMain pillar (CFT)Column built on Super-Beam-Special Prize

Continuous Steel-Concrete Composite
Girder Bridge Employing Compact
Sections
Prize winner: East Nippon Expressway Company Limited
Expressway companies in Japan have developed innovative structural types in the construction of expressway bridges, such as minimum main girder structures that adopt PC
slabs, and continuous composite structuresthat take into account the compound benefit
of using PC slabs and steel girders. One successful result in this direction was the structurally very simple continuous steel-concrete
composite two I-girder bridge. In order further to pursue rationalized bridge types, itwill be necessary to introduce new designconcepts.
To meet this need, East Nippon Expressway Company Limited introduced compact
section design to highway bridge construction-a first in Japan. The underlying ideaof this design concept is to fully utilize theperformance of various steel products to produce a more rational bridge structure. The
Kanayagou Viaduct is an expressway bridgethat was constructed using this new designconcept.
In the center section of the bridge span
where conventional continuous steel-concrete composite two I-girder bridges experience dominant positive bending, a neutral axis is located near the slab and the web
bears most of the tension. At this stage, it wasfeared that an unstable phenomenon called
buckling might occur in the compressedrange that partially remains.
To remedy this situation, a new designconcept was introduced. That is, if a section
is structured so that it does not cause buckling in the web and reaches a fully plastic
state, conditions are produced in which thecompression is mostly borne by the slab andthe tension is borne by the steel products. To
this end, rationalized sections can be realized that take full advantage of the featuresof both steel and concrete structures to prevent rapid collapse. It is the compact section
design concept that seeks to produce rational-

Compact Section Design Concept
σc ＜ 0.85σck－

Compressedrange

σc ＜ 0.85σck－

0.85σck

Plastic
neutral axis

Comparison of Steel Weight
Cross beam
41 tons

Main girder
264 tons

Conventional
designReduction to 82%
Cross beam
38 tons

Main girder
211 tons

Kanayagou
Viaductized sections by maximizing the use of theperformance characteristics of the structuralmembers.
The adoption of compact section designfor the Kanayagou Viaduct demonstrates
many advantages: reduced steel weight, restricted girder height, and the realization ofan economical and slender structure withgirders of equal height without a loss ofstructural performance.
￭－σｙElastic neutral axis＋＋＋
σｔ＜ σｙ(a) Before yielding
My or lowerσｙ(b) After yielding
My~Mp

σｙ

(c) Full plastic
Mp or higher

Comparison of Sectional Proportion
PC slab t=320

2,500
6,000
Conventional design(Allowable stress design method)

PC slab t=320

Kanayagou Viaduct employing a new designconcept based on compact section

1,500
6,000
Compact section design

April 2014 Steel Construction Today & Tomorrow 4

-Thesis Prize
Effect of Deck Plate Thickness of Orthotropic Steel Deck on Fatigue
Durability

Prize winners: Jun Murakoshi, Public Works Research Institute, Naoki Yanadori, Naoki Toyama, Honshu-Shikoku
Bridge Expressway Co., Ltd. and Toshiki Ishizawa, Takumi Kosuge, Shin Nippon Giken Engineering Co., Ltd.
Jun Murakoshi
1987: Finished M.S., Civil
Engineering, Tokyo Institute of Technology
1987: Entered Public Works
Research Institute(PWRI), Ministry of Construction
2008:Chief Researcher, Bridge and Structural
Technology Research Group, Center for
Advanced Engineering Structural Assessment and Research, PWRIThe effect of thickness ofdeck plate on fatigue durability of orthotropic steel
decks was discussed fromexperimental and analyticalresults to improve fatigue
durability of the structural details for the deck platecracks.

Wheel running fatigue tests were performed for full-scale test specimen with combination of 16/19 mm thickness deck plates(D16/D19) and 6/8 mm thickness ribs (V6/

V8) (Photo 1). Finite element analyses werealso conducted in order to clarify the effect ofthickness of deck plate on local stress at ribto-deck welded joints (Fig. 1).
￭

Fig. 1 Deformation and Principal Stress Vector Diagrams at
Rib-to-Deck Welded Joints for D12U6 and D19U6
D12

D12

Photo 1 View of testing by wheel
running test machine

D19(a) Cross section “a” (at rib-to-floor beam connection)
D19(b) Cross section “A” (at span center of trough rib)Research on Displacement Response Control Effect by Conventional
Steel Braces

Prize winners: Hiroyuki Hayashida, JFE Civil Engineering & Construction Corp., Izumi Miyashita,
Graduate School of Kumamoto University (formerly), Koji Ogawa, Graduate School of Kumamoto
University
Hiroyuki Hayashida
2010: Graduated from Department of Architecture,
Fukuoka University
2012: Graduated from Graduate School of Scienceand Technology, Kumamoto University
2012:Entered JFE Civil Engineering & Construction Corp.

The research examined the possibility thatconventional steel braces could be utilized asseismic response-control members.
Fig. 1 compares the maximum inter-story drift angle in entire stories of steel frameswith braces with that of pure rigid frames.
These frames are equal in strength. In therange of small inter-story drift angles, as assumed in the seismic response control design, the deformation of the braced frames issmaller than that of the pure rigid frames.
Fig. 2 shows the relation between thestrength-sharing ratio of the braces and the
maximum value of the inter-story drift angle
for the entire stories, with the strength of theframes fixed at a specified level. According
5 Steel Construction Today & Tomorrow April 2014

to the figure, when the sharing ratio of braces is increased, the response steadily decreases, but when the sharing ratio is increased beyond a certain level, the response tends torapidly increase.
The cause of the rapid increase of the response is attributable to the concentration of
deformation in a story. In this research an
equation is proposed that calculates the upFig. 1 Comparison of Inter-story Drift
Angle between Steel Frameswith Braces and Pure Rigid
Framesper limit of the strength-sharing ratio of braces so that deformation concentration could be
avoided. In an example shown in Fig. 2, theupper limit ratio is shown using the line of alternating long and short dashes.
￭Fig.2 Maximum Value of Maximum Inter-story Drift Angles
84th percentile
84th percentile
84th percentile
MediumMediumMediumPlastic Deformation Capacity of and Fracture Prevention Design Method
for Welded Moment Connections Strengthened by Thick Flanges
Prize winners: Keiichiro Suita, Professor, Kyoto University and five other members
Keiichiro Suita
1988: Finished Ph.D. Courseof Kyoto University
1988: Assistant Professor,
Kyoto University
2001: Associate Professor,
Kyoto University
2009: Professor, Kyoto University

With the aim of preventing the fracture of beamend welded connections in steel moment structures and improving the plastic deformation capacity of welded connections, a new structuraldesign approach was proposed in the current research. A key technology in this approach is toincrease the flange thickness of the beam ends
using as beam flanges steel products with varied thicknesses that are produced by a variableroll rolling mill (Fig. 1).
In order to verify the high deformation capacity of beams with increased flange thickness, the material properties of steel productswith varied thickness were confirmed using
various testing methods; and, the performanceof beams with increased flange thickness wascompared to the performance of beams withequal sections and increased widths using fullscale specimens of T-shaped welded beam-tocolumn connections (Photo 1). Further, stressconcentration at the toe of weld access hole wasanalyzed using the finite element method in order to propose a method to determine the mosteffective shape and dimensions for increased

thickness flanges in order to prevent fracturing.
The proposed design approach is effectivein improving the plastic deformation capacityof welded connections, particularly those madeduring on-site welding where quality control
over welded connections is difficult to implement and where the mechanical conditions affecting welded connections are difficult to control.
￭

Fig. 1 Thick Flange Method
Flange with increased
thickness

Photo 1 Specimen after testing

Proposal for a Method to Predict Volume Loss in Steel Members Using
FSM Assisted by Static Electric Field Analysis

Prize winners: Mikihito Hirohata, Nagoya University, You-Chul Kim, Osaka University, and Chunfeng
Jin, Osaka University
2008: Finished Doctoral
Course, Graduate
School of Engineering,Osaka University
2008: Specially Appointed
Assistant Professor, Joining and Welding Research Institute, Osaka University
2011: Assistant Professor, Graduate Schoolof Engineering, Nagoya University

In the current research, a method was proposedthat would predict corrosion-induced volume
loss of steel products by means of FSM assisted
by static electric field analysis.
In order to predict the volume loss of existing bridge members by means of FSM, it isnecessary to understand the secular (age-related) change in the electric potential difference
from the time of construction until the present.
However, it is impossible to measure the secularchange using the level existing, in sound condition, at the construction stage. To solve thisproblem, a parametric simulation that takes into account the various patterns of volume loss

was conducted by means of electric field analysis to find the curve that accurately predicts volume loss.
An electrode and sensing pin to measure theelectric potential difference were attached to the
web of an H-section steel as shown in Fig. 1.
The change in the electric potential difference
thus measured was evaluated as a permillage ofthe initial electric potential difference (FC value). Volume loss was applied at random to therange encircled using the red line (250×40 mm)
in Fig. 1. Meanwhile, prior to testing, an analysis was made using various volume loss patterns

Fig.1 H-section Steel Specimen(300×300×10×15 mm, 650 mm in length)
Volume loss
region

Pairs
1
2
3

to find the curve that would predict the volume
loss in the specimen. Fig. 2 shows the test andanalytical results. The test results in the figureshown using the symbol are predicted with relatively high accuracy using the volume loss prediction curve found in the analysis. That is, theresults thus obtained suggest the validity of themethod for predicting volume loss, as proposedin the current research.
￭

Fig. 2 Prediction Results of Volume
Loss of H-section SteelNon-dimensioned potential
difference change: FC (‰)

Mikihito Hirohata

Volume loss prediction curve
assembled by FEM

April 2014 Steel Construction Today & Tomorrow 6

Special Feature: Measures for Handling Giant Tsunamis
Three years have passed since the Great East Japan Earthquake occurred, and now reconstruction is expected to befurther accelerated in the disaster-stricken area. Given sucha situation, the pressing task for Japan is to structure society so that it is safety conscious and protected from disaster. This will be done by fully absorbing the lessons taught

by the serious human and physical damages inflicted mainly by the tsunamis generated by the earthquake.
Triggered by this movement, Issue No. 41 features the latest attempts to prepare for the future, specifically measuresto handle giant tsunamis employing steel structures.

Steel-structure Technologies
and Methods Used as Tsunami
Countermeasures

by Takeshi Mochizuki, Chairman of the Committee on Civil Engineering, the Japan Iron and SteelFederation; Kazuyoshi Fujisawa, Chairman of the Committee on Building Construction, the Japan Iron
and Steel Federation
Steel-structure Technologies andMethods Conducive to Preventing
and Controlling Tsunami Damage
In response to the Great East Japan Earthquake of March 2011, the Japan Iron andSteel Federation prepared proposals designed to “make social infrastructure highly
resistant to disaster” by maximizing the useof steel structures. The primary aim is to enable the quick recovery and reconstruction ofdisaster-stricken areas and to improve the disaster-prevention capacity of Japan. Amongthe many proposals are steel-structure technologies and methods that enhance the prevention and control of damage caused by tsunamis. These proposals are introduced below.
Fig. 1 Reinforcement Method for Existing Caisson Quay by Use of
Steel Pipe Sheet Piles or SteelPipe Piles

Reinforcement Method for Existing
Caisson Quays (Revetments) Using
Steel Pipe Sheet Piles or Steel Pipe
Piles
Fig. 1 shows an image of a method to reinforce existing caisson quays (revetments)that not only improves seismic resistance but
also prevents scouring of the caisson foundations. Caused by tsunami backwash, scouring can be prevented by installing embedded
steel pipe sheet piles in front of the existing
caisson quays (revetments). Also, steel pipe
piles can be substituted as the reinforcing
members in place of steel pipe sheet piles.
In addition, in cases where this method
is expected to provide reinforcement mainly against the leading wave of a tsunami, another variation is feasible in which the steel
products are aligned at the rear of the caissons.

Fig. 2 Reinforcement Method for Revetment by Use of
Steel Pipe Sheet Piles
Crest height of existingembankment

Existing footprotection stone
Liquefying layer
Steel pipe sheet pile

Non-liquefying layer

7 Steel Construction Today & Tomorrow April 2014

Reinforcement Method for Revetments Using Steel Pipe Sheet Piles
Fig. 2 shows a revetment reinforcement
method using steel pipe sheet piles. Thismethod not only raises the crest height of therevetment but also imparts the structural tenacity against tsunamis to the revetment byinstalling to the rear of the revetment a newparapet that is supported by steel pipe sheet
piles while at the same time utilizing the existing high-tide embankment.
Two features should be noted about theconstruction of new tsunami high-tide embankments. First, because there is no needfor large-scale remodeling of the existing revetment, the reinforcement work can be completed more quickly. Second, the reinforcement work can be carried out even in narrowsites with limited workspace.

Crest height of newembankment

Rubble stoneFig. 3 Effect of Double-wall Steel Sheet Pile on
Countermeasure against Overtopping
Collapse due
to overtopping

Double-wallsteel sheet pile
Collapse due
to overtopping

Fig. 4 Examples of Buildings Constructed Using “New Structural
System Buildings Employing Innovative Structural Materials”

Proto-type model of distribution center

Countermeasure against
Overtopping Using Double-wall Steel Sheet Piles
Fig. 3 shows the effects of reinforcement that uses double-wallsteel sheet piles to prevent embankment collapse due to overtopping during the high waterstage of tsunamis.
Among the features of thismethod are high seismic resistance (ground liquefaction resistance) provided by the installation of double-wall steel sheet
piles inside the embankment;
and retention of the embankment height to prevent inundation even when the embankment slope might be broken due
to overtopping.

A New Structural System
for Building Construction“New Structural System Buildings Employing Innovative Structural Materials” is a joint government-private sector
R&D project. Specifically, buildings using
this new structural system can withstandgreat earthquakes with a seismic intensity
level of 7 and are constructed using both 780
N/mm2-grade high-strength steel (H-SA700)
and energy dissipative system.
Capitalizing on further conceptual enhancement of buildings using this new structural system, it will be feasible to construct
raised street areas and multi-storied industrial facilities that can fend off the wave forc-

es produced by tsunamis and floods, as seenin Fig. 41).
Steel-structure Building for Use as a
Disaster Emergency BaseFig. 5 shows a steel-structure building that isused as a disaster emergency base. It has a pilotis structure that is highly resistant to earthquakes and tsunamis, is useful for multiple
purposes, and can serve as a regional symbol.
The building employs a pilotis structurethat has a height greater than the assumed
tsunami height and uses high-strength, highrigidity concrete filled steel tubes (CFT) thatenhance the building’s safety against tsunamis. It also adopts an energy dissipative system that uses buckling-restrained braces forthe upper building section, thereby improving seismic resistance. In addition, the adoption of a large-span structure offers flexible
space, which allows for multi-purpose use inan emergency.
♦♦♦♦♦
The technologies and methods that were developed in Japan and introduced above are
expected to contribute to the security andsafety of people living in Pacific-rim nations.
￭
Reference
1) New Structural System Buildings Employing
Innovative Structural Materials-Proposal
to Use These Buildings for Restoration andReconstruction, Steel Construction Today &Tomorrow No.35 March 2013, pp.15-16.

Proto-type model of regional baseConcrete-filled steel tube (CFT)

Pilotis structure

Buckling-restraint brace

Damping structure

Fig. 5 Steel-structure Building for Disaster Emergency Base

Proto-type model of dense urban area
April 2014 Steel Construction Today & Tomorrow 8

Measures for Handling Giant Tsunamis

Vertically Telescopic Breakwaterthe World’s First Prototype

by Makoto Kobayashi, Obayashi Corporation; Taro Arikawa, Port and Airport Research Institute;Kazuyoshi Kihara, Mitsubishi Heavy Industries Bridge & Steel Structure Engineering Co., Ltd.; Hiroshi
Inoue, Toa Corporation; and Hirotsugu Kasahara, Nippon Steel & Sumikin Engineering Co., Ltd.
sists of upper and lower steel pipe piles arranged in multiple rows and is usually placed
under the seafloor coinciding with ship navigation lanes. In times of emergency, such as
for tsunamis and high waves, theFig. 1 Image Drawing of VTB
upper piles are made to float inorder to protect the various facilUsual time Placing upper pile under the seabed
ities located inside ports and harbors (Fig. 1).
It has been confirmed that in
the Great East Japan Earthquakethat occurred on March 11, 2011,
conventional-typebreakwaters
contributed to the mitigation oftsunami damage. If the VTB is▽Seabedapplied, not only this breakwater
will pose no threat to ship navigaUpper piletion, it will also provide a means
to prevent flowing-in of tsunamis
The vertically telescopic breakwater (buoyancy-driven vertical piling breakwater; hereafter abbreviated as VTB) is a movablebreakwater based on a new concept. It con-through navigation routes.
The following introduces an outline of the
VTB and the hydraulic model tests and fieldtests that were conducted to examine and verify key technological factors.
Structural Outline and Raising
Mechanism
The new breakwater is composed of a sheathing structure in which the upper piles are inserted into the lower piles (Fig. 2). The upper
piles are raised by filling them with compressed air and are lowered by releasing the
air through exhaust valves. Both operations
are executed by a remote control system.
Transfer of horizontal forces (wave force,etc) takes place in the part where the upperand lower piles overlap.

Issuance of tsunami and high wave warning
Raising Supply of air to raise the upper pile
Tsunami, high wave

Fig. 2 Schematic Drawing of VTB
Sea side

Port side
Exhaust valve

Raising
Air chamber
Buoyancy tank

Upper pile (movable)

Communicating pipe
Air supply
Canceling of tsunami and high wave warning
Lowering Exhausting of air to lower the upper pile

Exhausting

To on-land air
supply tankSeabedOverlapped part

RubbleLowering
Air supply pipe
Lower pile

Air bubbles

9 Steel Construction Today & Tomorrow April 2014

Hydraulic Model Test
The effect of the breakwater on stopping atsunami was confirmed by means of a hydraulic model test. The test was conducted
at a Large Hydro-Geo Flume (length 184 m,
depth 12 m, width 3.5 m) at the Port and Airport Research Institute by installing a breakwater model on a scale of 1/5. Photo 1 shows
the test conditions.
The test results show a transmission coefficient of 0.25~0.3, confirming that the
breakwater offers sufficient effectiveness in
stopping a tsunami.
Field Test
The field test was conducted at Numazu Portin Shizuoka Prefecture during the period
from September 2006 to May 2009. The test
specimen was a one-set specimen composedof an upper pile (1.422 m in diameter, 14.75
m in length) and a lower pile (1.600 m in diameter, 16.75 m in length). Two piles (1.422
m in diameter), which were fixed to the seafloor, were installed at both sides of the specimen (Photo 2). The major test items and results are introduced below:• Raising and Lowering Tests
Testing of the raising and lowering mechanisms was conducted by introducing air
from the supply tank and draining it throughthe exhaust valves. Raising was completed in 200 seconds after the supply of air began. While the raising and lowering operations were repeated 100 times, the raising andlowering conditions remained stable, thereby confirming the reliability of the air supply system.
• Wave Response Tests
These tests were conducted with the upper
pile fully floated in order to clarify the breakwater’s response to waves. The result confirmed that the breakwater’s response could
be forecasted by means of oscillation analysis using the upper pile as the floating structure.
• Surveying the Marine Growth andSteel Pile Corrosion
The upper pile was re-raised after 1 year installation. It was confirmed that the surfaceof the upper pile was free of any marine
growth and free of any significant corrosion(Photo 3). This fact seems to attribute to an
environment of extremely low light and negligible residual oxygen inside the lower pilein which the upper pile was encased.
Disaster-prevention Plan Employing
the VTB
A structural outline of the VTB, its protection

effect on waves, and verification of its raisingand lowering systems was introduced above.
In Japan, two great earthquakes are forecasted to occur in the Nankai and Tonankai
areas in the near future. In Wakayama-Shimotsu Port where great tsunami damage ispredicted as a result from these earthquakes,

a tsunami disaster-prevention plan is being
promoted that applies a VTB.
￭

Front of pile (sea side)

Rear of pile (port side)
Photo 1 Hydraulic model test

Encasing of pile

Photo 2 Field test

Surface of upper pile after raising (thickness of marine growth: negligible)

Marine growth of neighboring fixed pile (thickness ofmarine growth: 10 cm)

Photo 3 Survey of marine growth
April 2014 Steel Construction Today & Tomorrow 10

Measures for Handling Giant Tsunamis

Flap Gate Tsunami Breakwater: Tsunami
Disaster Prevention/Mitigation Facility
by Kyoichi Nakayasu, Hitachi Zosen Corporation

At 14:46 on March 11, 2011, Japan was
rocked by the Great East Japan Earthquakewith its epicenter located off the coast of Miyagi Prefecture. The great tsunamis causedby this earthquake wreaked serious devastation over a wide area along the Pacific coast,
ranging from Hokkaido and Tohoku to Kanto. In spite of the fact that the quake occurred
during the daytime and that there was a comparatively long time to escape before the firsttsunami arrived, the initial delay in evacuation procedures due to confusion caused by
the earthquake itself, normalcy bias, and poor
communications resulted in an increase in thenumber of tsunami victims.
On the other hand, while recognizing thedanger posed by tsunamis, many people stillheaded towards the sea in order to close thesluicegates and land locks. As a result, someof these people were engulfed by the tsunamis. A news release issued by the Cabinet
Office on August 29, 2012, clearly states thenature of proper tsunami countermeasures:“Quick evacuation is the most important andeffective countermeasure against tsunamis”
and “Every tsunami countermeasure should
be designed as a means of supporting quick
evacuation.” These two statements indicate
the future direction of tsunami disaster prevention and disaster mitigation facility.
The flap gate tsunami breakwater (flapgate-type tsunami disaster prevention anddisaster mitigation facility) not only reflects
movement in the above-mentioned direction,
but it also demonstrates reliable functionality in an emergency, poses less of an obstaclein daily life, and reduces maintenance efforts
to a minimum. The following feature presentation introduces the expected application effects and the latest developments in the flap
gate tsunami breakwaters.
Outline of the Flap Gate Tsunami
Breakwater
The flap gate tsunami breakwater is a cutoff
equipment that needs neither external power nor manual operation and represents a fusion of the raise-type gate, with many river
installation records, and the flap gate. The
conventional flap gate features a hinge that is
installed in the upper section of the flap (Fig.
11 Steel Construction Today & Tomorrow April 2014

Application of Tsunami Breakwaters• Structural Outline
Fig. 3 shows an image of installed flap gate
tsunami breakwater. It is composed of threemain members: the gate leaf, the box structure that houses gate leaves, and the tension
rods that transfer the load working on the upper section of the gate leaf to the box structure when the gate is rising.
The gate leaves are linearly arranged
across the opening of a port and form a continuous breakwater; they rise, fall down andrevolve around a rotating axis located in thebottom section of the structure.
The buoyancy required to lift the gate is1), and the gate automatically opens and closes in response to differences in water level infront of and behind the flap gate. Meanwhile,
the raise-type gate has a hinge installed in thelower section of the gate (Fig. 2) and controls the water flow by changing the angle of
the gate by means of a driving device. In theflap gate tsunami breakwater, the center ofrotation is located in the lower section of thegate as in the raise-type gate. And, as withthe conventional flap gate in response to tsunamis, high tides and floods, the flap gate on
the tsunami breakwater rises and falls down
employing the difference in water level infront of and behind the gate.
Fig. 1 Outline of Flap Gate

Fig. 2 Outline of Raise-type Gate

Hinge

Driving device

Gate leaf

Water flow

Water flow
Water flow

Support section(hinge)Gate leaf

Fig. 3 Image of Installed Flap Gate Tsunami Breakwater
Example of installation oftsunami breakwaterPort
insideLand
Tension rod

Sea

Port
outsidePort outside

Port inside

At the time oftsunami attack

Port outside

Port insideBox
structure

Gate leaf

In normal state

Risingsecured by a supply of air to the gate leaf’s airchamber in normal time. Under normal conditions, the end of the gate leaf is moored using a hook installed on the box structure toprevent the gate from floating. When a tsunami is forecasted, the mooring hook is released and the gate leaves rise by means of
its own buoyancy to the surface of the water. Then, as the tsunami arrives, the gate rises with no need for power and by the use ofa difference in water level due to the rise of
tidal level created by tsunamis until it reaches the specified angle.
The load working on the gate is transferred to the foundation of the box structure
via tension rods and the rotating axis in thebottom section of the gate. This gives stability to the flap gate tsunami breakwater by establishing friction resistance between the box
structure and the rubble mound.
• Features and Expected Application
Effects
The flap gate tsunami breakwater exhibitsthese features: “The disaster protection area
is wide because of its installation outside existing seawalls”; “The buoyancy required torise the gate is supplied under normal conditions”; and “Tsunami wave force does notblock the flap gate closing”. To these ends,
the following application effects can be expected:♦ Even when attacked by the largest tsunamis, the time before inundation begins canbe delayed, thereby extending the evacuation time.
♦ Because large-scale mechanical devices are
not required, construction costs can be suppressed, and the maintenance burden is reduced.
♦ It is also possible to automatically close waterways employing only the rising water level of tsunamis, and the breakwater clearly
demonstrates its functionality during disasters that damage the communications infrastructure.
LatestDevelopments•
Development of the flap gate tsunami breakwater started in 2003. And then the breakwater’s basic performance was examined andimproved by means of various tests, with thelaboratory tests required for practical application being nearly complete by 2009. From2010 to 2012, the basic function and reliability of the breakwater were verified jointly by
Hitachi Zosen, Toyo Construction and Penta Ocean Construction by means of practicalsea area tests.
Photo 1 shows the practical sea area tests.
The tests were conducted at the Yaizu Fish-

ing Port, Shizuoka
Prefecture, with theaim of confirming
Tsunami/high tide breakwater
the reliability of therising and fallingdown operations,stability of the gatewhen fallen down,
and the reliabilityof the maintenanceand safety.
The device used
for the tests was installed in February 2011, and for
Photo 1 Installation of testing device at practical sea area
about 2 years up to
March, 2013, tests
were conducted that included 151 floatation/ The operating mechanism of the flap gate offalling-down operations and 14 months of land lock type is similar to that of the flap
observation with the gate in the fallen-down gate tsunami breakwater. Because the gate
position. The tests confirmed that there are automatically rises with inundation, the folno problems with the reliability of the break- lowing application effects can be expected:
water’s movement or its stability in the fall- ♦ Because there is no need for gate operation,
en-down state. In addition, during the test peevacuation activities will not be inhibited.
riod, equipment conditions were constantly ♦ Even if a power supply infrastructure and amonitored to accumulate various operational
telecom infrastructure suffer serious damdata. At the same time, periodic observations
age, the flap gate of land lock type can sureand parts exchanges were conducted by divly demonstrate its function.
ers to confirm the stability and safety of un- ♦ Because the gate can be opened at any time,derwater operations. Meanwhile, the test reits effect on daily life is less, and in an emersults were publicly announced by the threegency, the lock gate can be used as an evaccompanies in October 2013. For more deuation route.
tails, please go to: http://www.hitachizosen. ♦ Because of the gate’s simple mechanicalco.jp/products/products026.html
composition, trouble is not likely to occur;and because of the ease of maintenance, theApplication of the Land Lockmaintenance burden is lessened.
LatestDevelopments•
Photo 2 shows the condition to confirm the Promising Application of Flap Gate
gate movement due to water flow when the A notable feature of the flap gate tsunami
flap gate tsunami breakwater is applied in the breakwater (flap gate-type tsunami disasterflap gate of land lock type. Development of prevention and mitigation facility) is that thethe flap gate of land lock type started in 2009, breakwater can be operated using the natuand research efforts were directed toward the ral forces, an outline of which was reported
prevention of rapid rising and falling-down above. While tsunami disasters cannot comof the gate and the retention of gate strength pletely be prevented using only the flap gate
and rigidity against passing vehicles.
tsunami breakwater, we will be glad if thisIn 2011, the durability of the gate was flap gate could provide even limited help in
confirmed in practical field application us- structuring a safe society.
￭ing verification testing devices, and the operating conditions wereconfirmed using a waterflow generation tank. In
May 2013, the first practical flap gate of land lock
type with an improved architectural design was installed.
• Expected Applica- Photo 2 Confirmation of flap gate movement due to water flow
(applied as land lock)tion Effects
April 2014 Steel Construction Today & Tomorrow 12

Measures for Handling Giant Tsunamis

Tsunami Evacuation Measures that
Match Local Characteristics
by Mitsuo Seki, Takenaka Corporation
Initiatives to Build Tsunami Disasterprevention Districts
The huge tsunamis caused by the Great East
Japan Earthquake were disastrous to coastal areas and claimed the lives of many people. Currently, initiatives are being called forthat promote the creation of tsunami-prevention districts by means of multifaceted protection systems that combine the use of both
software and hardware.
Capitalizing on high-precision simulation technology and rich experience in theconstruction of disaster-prevention facilities,
Takenaka Corporation is undertaking the creation of a disaster-prevention district that accurately matches local characteristics.

it is important to properly assign the functions of the evacuation facility to the multiple
levels by relying on a tsunami run-up analysis and an evacuation simulations, based on
detailed topographical and other conditionsof the urban area (Fig. 1).

uation facility are introduced below (Photo1):• High Resistance to Seismic andTsunami Forces
The facility would adopt an intermediate-story base-isolation structure with the base-isolation layer located at a height greater thanthat of the assumed tsunami height. Circular
RC cores capable of fending off wave forces
would be arranged on both sides of the facility. Further, the center section of the facility
would be a suspension structure employing ahigh-strength steel frame.
• Local Disaster-prevention Base
The facility would be a self-sustaining structure during the period from normalcy throughthe disaster stage and then through reconstruction and would allow multiple uses. It
would include a warehouse for disaster-protection equipment and goods, securely maintain energy supply and communications
functions, and show the networks for evacuation routes.
￭

Function and Arrangement of
Tsunami Evacuation Facilities
The tsunami evacuation facilities can be organized into 3 levels and arranged as shownin Fig. 2.
• Level 1 Tsunami Evacuation Facility
Vulnerable pedestrians should be able toreach a Level 1 facility within 15~20 minutes after evacuation begins, and the facility
should be able to provide minimum life support functions until relief arrives.
• Level 2 Tsunami Evacuation Facility
A Level 2 facility should be able to offer
life support functions for a minimum of 3days and, with relief support, be able to provide evacuees with safe living conditions forabout 1 month.
• Level 3 Tsunami Evacuation Facility
A Level 3 facility would be responsible
for covering a wider disaster-stricken area,
would have its own power source, maintaincommunications functions, and offer emergency medical treatment capabilities. Further, it would serve as a branch office of thelocal administration.

Plan to Build a Tsunami Evacuation
District
The characteristics of a tsunami are greatly affected by the local topography and local river/urban area conditions. Accordingly,
when planning a tsunami evacuation district,Fig. 1 Example of Tsunami Run-up
Analysis

Tsunamiheight4.0
3.0
2.0

Plans for a Tsunami Evacuation Facility
The general plans for a Level 2 tsunami evac-

1.0
0.0

Photo 1 Appearance of tsunami evacuationbuilding

Fig. 2 Concept of Arrangement of Tsunami Evacuation Facilities (Level 1~3 Functions)
Flotation
facility

Green
mound

Verticalevacuation
moving line

Level 1

Flotation
Flotation facility
During normalcy
Shipbuilding
works etc

Level 1

Evacuation
tower

Evacuationbuilding

Evacuation tower

Evacuation toelevated frame

EV

Balcony

StairwaySliding
post

Slope

13 Steel Construction Today & Tomorrow April 2014

Evacuation building
Storage

Membrane Evacuation
roof
deck

EnergyBase-isolation
layer
PilotisEvacuation deck
Existingbuilding

Building serving as local function base

Level 3: Function for
local base

Level 3
Evacuation building

Heliport
During tsunami
disaster

Verticalevacuation
moving line

Level 2: Function for local evacuation base

Level 2

Vertical evacuation moving line

Primary-school
evacuation deck

Urban planning

Important function facility

High rise:
Housing
Low rise: Commercial
and industrial facilityay
ip qu
e sh Self-sustaining
3-dimensional city

e-siz

Larg

NetworkMeasures for Handling Sliding post Tsunamis

Tsunami Evacuation Building: Arch
Shelterby Yasushi Watanabe, Shimizu Corporation
Media pictures clearly depict the destructive and unparalleled power of the tsunamis
caused by the Great East Japan Earthquakeof March 11, 2011. As a solution for handlingthe force of tsunamis, we introduce a tsunami evacuation building designed to withstandthe external forces produced by a 20 m-hightsunami.
Building Outline• No. of stories: B0-7F-P1• Structure: Arch wall of RC construction; Inner building of steel construction (mid-story isolation structure)• Building area: 1,450 m2• Total floor area: Arch wall 3,631 m2; Innerbuilding 6,019 m2• Building height: About 34 m
(Photo 1)
The building is expected to offer a solution for enterprises around the nation thathave a plan of operation in coastal areas andfor local governments in urban coastal areas
where moving to high ground is difficult.

Fig. 1 Composition of Structure
Hybrid structure that resists tsunami wave and adopts mid-story isolation system
Arch Shelter is composed of a dual structure: The oval-shaped arch wall resistant to 20 mhigh tsunami external force is provided in the outside of the building, and in the inside theinner building having mid-story isolation function is installed. It can simultaneously resist
tsunami external force and seismic force.
Arch wall that resists tsunami
external force by means of its
arch structure (Arch wall)
Structural rib that protects thebuilding from drift collision

Seismic-resistant“Inner building”

TsunamiPolycarbonate+Tempered
double-layer glass windowthat resists tsunami wave
pressure

Isolation layer
First-floor pilotis section is used
for shops in normal stateFig. 2 Structural Outline
RC core wallRC
peripheral
fin

Steel frame for
office space

Isolation layer
Outer RC
shell

PilotisMat
foundation

structure with midstory isolation layer
between the first andsecond floors. The
foundation structure
employs both a mat
slab and a pile foundation to resist buoyancy during a tsunami attack.

Structural Examination
With an assumed tsunami height of 20 m, the hydraulic pressure
and the buoyancy working on the building
were calculated using a hydraulic test anda volume of fluid (VOF) analysis. The results of these calculations were applied in the
structural examination of the tsunami evacuation building (Photo 2). Both the upper
structure and the foundation were designed
so that the strength of the members would exceed the working stress.
￭

Cast-in-place concrete pile

Photo 1 Perspective view of appearance of Arch
Shelter

Structural Outline
The first-floor section of the building, excluding the core sections provided on bothsides, is of the pilotis type. When a tsunami
strikes the building, the seawater will passthrough the pilotis section, thereby mitigating the tsunami’s force (Figs. 1 and 2).
In order to effectively resist the external force applied by a tsunami, the building adopts a floor planning with oval-shaped
peripheral arch wall as used for arch dams.
Outside the building periphery, there is a
curved RC wall structure with attached finthat serves as both a balcony and an evacuation passage. The inner building has the steel-Hydraulic test

Stress analytical result
VOF analytical result

Photo 2 Tests and analytical results
April 2014 Steel Construction Today & Tomorrow 14

Measures for Handling Giant Tsunamis

Building for Use as a Tsunami
Countermeasure: T-Buffer
by Masaaki Watanabe, Taisei Corporation
The “T-Buffer” is a new type of building used
as a tsunami countermeasure. Although it isexpected to serve as an ordinary office building during normal times, it always retains its
functionality as an evacuation center during
a tsunami emergency. A major feature of thebuilding plan is the built-in structural redundancy against collisions with drifting objects,
in addition to the wave pressure caused bytsunamis, by allowing partial damage to thecolumns. (See Photo 1)

Evacuation space
Equipment space

Fig. 2 Section

Concrete bearing wall that resists wave
pressureCore that functions as shelter (lavatory,
stairway)
Allowing damage of curtain walland column

Stopping drifting object
Mat slab that resist scouring

Photo 1 Perspective view of appearance

Structural Outline
The main structural feature of a T-Buffer building is that the core bearing wall located at thecenter of the building bears the vertical load
and the seismic/tsunami loads, and that the peripheral columns of the first floor support only the building’s exterior members but do notbear the vertical load of the building itself.
Fig. 1 Structural Model
Belt truss

The peripheral columns serve as buffersthat resist the wave pressure of tsunamis andthe collision force of drifting objects. This
prevents fatal damage to the bearing wall
and as a result allows for the quick recoveryof building functions after a tsunami attack.
Even if the first-floor peripheral columns are
by any chance damaged by wave pressure or
collisions with drifting objects, the building isconstructed so that the vertical load is borneby both the belt trusses that are located in the
peripheral sections of the upper floors and thesuspension members that are located in the
top-most floor to support the entire building
structure.
A piling foundation is adopted for the foundation, in conjunction with a mat slab in orderto resist scouring.(Refer to Figs. 1~3)
Suspension
memberFig. 3 Plan

Protection of Human Life andBuildings from Tsunamis
The first-story height is determined so thatit surpasses the design inundation height.
However, even in cases when the tsunami
height surpasses the height of the first story, the design approach used for first story is
also adopted for the second and higher stories, thereby allowing the building to copewith tsunamis of any height. Furthermore,in a T-Buffer building, waterproof doors
are adopted for the wall openings in order
to offer evacuation passageways to the upper floors and to allow the building to serveas an evacuation shelter. These design approaches create a suitable “building for use
as a tsunami countermeasure” that can protect both human life and building functionality from tsunamis.
￭
First-floor peripheral column

Absorbing andbuffering collision force ofdrifting object

Core bearing
wall (t=750 mm)

First-floor peripheral column(Vertical load is not borneby the column)

15 Steel Construction Today & Tomorrow April 2014

Mitigating tsunami wave
pressure working on core
Stopping
drifting object

Measures for Handling Giant Tsunamis

Structural Design Method for Tsunami
Evacuation Buildings
by Tomokazu Tateno, Kajima Corporation
The disastrous Great East Japan Earthquakethat occurred on March 11, 2011 caused serious damage in the Tohoku to Kanto areas.
The dead and missing numbered more than
20,000, and more than 100,000 buildings collapsed or were washed away. Most of thedamage was caused by tsunamis.
There is a growing call for tsunami evacuation buildings to be specified as emergency
evacuation sites in areas where it is difficult
for residents to move to high ground before
a tsunami arrives. For that purpose, it is necessary to confirm the structural safety of suchtsunami evacuation buildings.
In the building standards improvement
project promoted by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT)
for 2011, specific proposals concerning design tsunami load were made based on the results of damage surveys conducted in the disaster-stricken areas of the Great East Japan
Earthquake1). The results of these surveys arereflected in the temporary guidelines (MLIT,
Nov. 17, 2011) concerning the structural requirements for tsunami evacuation and otherbuildings.
In the following, an outline of the structural design method for tsunami evacuationbuildings shown in the temporary guidelines
is introduced.
Structural Design Method for Tsunami
Evacuation Buildings• Confirmation of Application Ranges
The primary condition for a tsunami evacuation building is that its seismic resistance bein conformance with the Building Standard
Law for newly built buildings and that it beadaptable to the Seismic Resistance Diagnosis Standards for existing buildings.
• Calculation of Tsunami Wave Force
Next, the tsunami wave force is calculated. Fig. 1 shows the tsunami wave pressure
shown in the temporary guidelines. The wave
pressure when a tsunami with a design inundation depth h collides with a building is equivalent to the hydrostatic pressure a times the design inundation depth h. While this equationis set in reference to the hydraulic model test
results by Asakura et.al2), it is also known, as aresult of disaster surveys of the Great East Ja-

Fig. 1 Wave Pressure
due to Tsunamis

ciation3).
At Kajima Corporation, joint reBuilding
search is underway between Kajima
Design inundation depth
and the Institute of Industrial Scienceof the University of Tokyo, in supportof improving the building standards.
Area with no shelter
Area with shelter
The specific programs being promotNo shelter
Shelter
ed using hydraulic model tests andsimulation are: to confirm the mitigatpan Earthquake, that the disaster level differs ing effect that providing openings has on tsunami wave force; and to examine the buoydepending on local conditions.
The wave pressure explained above is in- ancy generation mechanism, both of which
corporated as the water depth coefficient a in aim at pinning down the design tsunami wave
the temporary guidelines. Fig. 1 shows the co- load.
￭
efficient depending on local conditions.
• Calculation of Buoyancy
Photo 1 shows a hotel building, located in
Onagawacho where an inundation depth of
15 m was observed, that was turned over ata point about 70 m from its original site. It isbelieved that the building was washed away
and overturned by buoyancy that was causedby the horizontal force and rapid rise in water level caused by the tsunamis and, further,by ground liquefaction. In order to prevent
this type of damage, it is necessary to conduct
structural design with an appropriate reckon- Photo 1 Overturned and washed away building
ing of buoyancy.
• Design of Structural Frames and Examination of Sliding and Overturning
In the design of structural frames, it must be
confirmed that the horizontal strength of abuilding is greater than the tsunami load. The
horizontal strength is found by analyzing theload increments attributable to the wave pressure distribution of the tsunami load; and thebuoyancy is taken into account in the analysis.
Further, the foundation is to be designed so Photo 2 Inclined buildingthat the building does not slide and overturndue to the tsunami load; and, depending on References
the situation, piles are to be used in the foun- 1)Institute of Industrial Science, the University
dation. In addition, due consideration must be of Tokyo: Building Standard Improvement
paid in the design to the inclination (Photo 2) Promotion Project for 2011 (40. Examination
Conducive to Improving Building Standards inand to drifting objects.
Promotion of Joint Research
An outline of the structural design method fortsunami evacuation buildings has been introduced above. An instruction manual and design examples are available at the website of
the Japan Building Disaster Prevention Asso-

Tsunami Dangerous Areas, March 20112)Asakura et al: Experimental Research on
Wave Force of Tsunami Overtopping the
Revetment, Journal of Coastal Engineering,Vol. 47 (2000)
3)The Japan Building Disaster Prevention
Association, http://www.kenchiku-bosai.or.jp/
seismic/tsunami_text.html
April 2014 Steel Construction Today & Tomorrow 16

JSSC Operations

10th Pacific Structural Steel
Conference (PSSC 2013)

The Pacific Structural Steel Conference(PSSC) is an international conference sponsored by the steel construction-related organizations of 10 nations (the United States,
Australia, Canada, China, Chile, Japan, Korea, Mexico, New Zealand and Singapore).
Since the first session in 1983 in New Zealand, the participating nations have alternatedin holding the conference every three years.
The Tenth Pacific Structural Steel Conference was held for three days from October 9
to 11 in Sentosa, Singapore.

At the tenth conference, about 300 individuals participated from all around theworld-the European nations, India, South
Africa and elsewhere-in addition to theusual 10 nations.
On the first day of the conference, 13 keynote lectures were delivered (Table 1), including an address by Prof. Masayoshi Nakashima of the Disaster Prevention ResearchInstitute, Kyoto University, who represented
Japan. Among the major themes of the keynote speeches were progressive collapse, Eurocodes, and the latest examples of construction in various nations.
On the second and third days, the sessions
were divided into four groups, inwhich 270 theses were presented with active
Q&A. A total of 48 theses were deliveredfrom Japan, followed by 60 theses from China. These two nations accounted for about
half of all the presentations (Fig. 1). Whenclassified by field of specialization, 40 theses
referred to seismic resistance, or 20% of theproceedings. Other prominent fields included
structural design, new construction technologies, and joints (Fig. 2).
The next PSSC is scheduled to be held in
2016, with China as the host nation. China
hosted a previous session in 2010. In total,
China will have held three PSSC sessions,which strongly indicates the robust activitiesof that nation’s construction industry, including steel construction.
￭

Fig. 1 Proceedings at PSSC 2013 by Country(Total Number: 194)South Africa, 1Opening ceremony at PSSC 2013

A scene of PSSC venue

Table 1 List of Keynote Lectures
1.How to Improve Resistance to Progressive Collapse When Designing
Steel and Composite Buildings
Professor David A. Nethercot
2.Progressive Collapse Analysis of Buildings: The Middle-Way Approach
Professor Chan Ghee Koh
3.Needs of Physical Evidences for Advancement of Steel Research
Professor Masayoshi Nakashima
4.Main Issues on Seismic Resistance of Steel Frames Coupled with Concrete Core for Tall Buildings
Professor Guo-Qiang Li
5.Current Developments for International Steel Design Codes
Professor Reidar Bjorhovde
6.Second-Order Plastic Analysis of Steel Frames by a Single Element Per
Member Allowing for Arbitrarily Located Plastic Hinge
Professor Siu-Lai Chan
7.Structural Design of Steel High-Rise Buildings in Korea
Jong-Ho Kim
8.Advancements and Achievements in Structural Steel in Australia
Professor Brian Uy
9.Deformation Characteristics of Shear Connections with Different Configurations Under Complex Loadings
Professor Kwok-Fai Chung
10.Impact of Structural Eurocodes on Steel and Composite Structures
Associate Professor Sing-Ping Chiew
11.Flower Dome and Cloud Forest Conservatories @ Gardens by the Bay
Allan Teo
12.Design of the Singapore National Stadium Roof and an Assessment of
the Potential Benefits of High Strength Niobium Steels
Mike King

17 Steel Construction Today & Tomorrow April 2014

Canada, 3
US, 2

Czech, 2

New Zealand, 5

Turkey, 1
Vietnam, 1
UK, 3
Italy, 2
India, 6
Poland, 2
Portugal, 4Greece, 1Netherlands, 2
Hong Kong, 3
Malaysia, 5Luxemburg, 1Singapore, 19
Australia, 12
Korea, 10
Japan, 48

0

10

20
30
40
50
Number of proceedings

60

China, 61

70

Fig. 2 Proceedings at PSSC 2013 by Field ofSpecialization and Country
CyclicFabrication Construction & Erection
Impact/Shear Wall
Column & Tube
Design & Innovation
Progressive Collapse
Wind & Vibration
AnalysisFire
Bridge & Offshore
Roof & Dome
BridgeBuckling
Connection & Joint
Seismic
Fatigue
Cold Formed
Stud/Shear Connection
High Strength/Performance Steel
BeamThin Member

0 10 20 30 40
Number of proceedings

Japan
China
Korea
Australia
Singapore
Luxemburg
Malaysia
Hong Kong
Netherlands
GreecePortugal
Poland
India
Italy
UK
VietnamTurkeyNew Zealand
Czech
US
CanadaSouth Africa

JSSC Symposium 2013 on Structural
Steel Construction
The Japanese Society of Steel Construction(JSSC) has annually held its Symposium on
Structural Steel Construction since 2004. The
major aim of this symposium is to comprehensively and functionally link the operating results of JSSC’s various committees andworking groups and to provide a venue forexchange between JSSC members and others
working in the field of steel construction. The
2013 symposium was held November 14 to
15 in Tokyo.
The 2013 symposium offered the wide
range of programs shown in the table below. Also, the works that received one of
JSSC’s commendation prizes for outstanding achievement were introduced in a panel
exhibition. (See pages 1-6 for the prize-winning works).
Insofar more than 800 people participated in the two days of sessions, the symposium was clearly found to be a useful venue
for exchanges between researchers and engineers working in steel construction and forcollecting the latest information on steel construction.
￭

Academy session on steel construction technologies
Social gathering

Session on international operations

Prize winners in JSSC’s commendations for outstanding achievements

Programs and Sessions at the Symposium 2013
Novbember14, 2013
General program

Academy session

Stainless Steel Session
A(Stainless Steel Technology
M
and Standard Committee)
Engineering Session(Technology and Standard
Committee)
P
M

Commendations for
Outstanding Achievements
Commendation ceremony
Lecture by prize winners
Special Lecture(Lecture by JSSC Prizewinner)Load-bearing Capacity and
Joints(Civil engineering)Members (1)(Building construction)

Structural Analysis
and Design(Building construction)

Corrosion/Corrosion Protection
and Repair/Reinforcement(Civil engineering)Members (2)(Building construction)

Structural Analysis
and Others(Civil engineering)

Measurement/Inspection/
Monitoring(Civil engineering and building
construction)

Members (3)(Building construction)

Materials(Building construction)

Vibration/Vibration
Control/Seismic Resistance(Civil engineering)

Fatigue/Fracture(Civil engineering)Vibration/
Seismic Resistance (1)(Building construction)

Connections (1)(Building construction)

Maintenance/
Management (1)(Civil engineering)Vibration/
Seismic Resistance (2)(Building construction)

Connections (2)(Building construction)

Maintenance/
Management (2)(Civil engineering)Social gathering
November 15, 2013
A
M
Session on International Operations(Joint session: IABSE and JSSC)
P
M

April 2014 Steel Construction Today & Tomorrow 18

To Our Readers

Greeting from the Chairman of JSSC’s International
Committee

by Toshiyuki Sugiyama
Chairman, International Committee,
Japanese Society of Steel Construction(Professor, Graduate School of
Yamanashi University)

Starting with issue No.
26 of Steel
Construction Today &Tomorrow publishedin 2009, ourInternational
Committee has been
responsible for theeditorial planning of
one of the threeissues publishedannually. Since its inauguration, the JapaneseSociety of Steel Construction (JSSC) has
conducted wide-ranging activities in the form ofsurveys, research and technologicaldevelopment aimed at promoting the spread ofsteel construction and at improving associatedtechnologies and, further, to extend cooperation
to related organizations overseas.
Following the merger of JSSC with theStainless Steel Building Association of Japan in
2010, JSSC’s field of operation expanded toinclude not only carbon steel but also highly
corrosion-resistant stainless steel. Consequently,
we intend to actively transmit information
throughout the world that is related to a wider
range of steel construction areas.
As was true in issue No. 38, the previous
special issue on the JSSC for which theInternational Committee was responsible, ourcurrent issue, No. 41, introduces the excellent
works and theses that received the prize in
JSSC’s commendation for outstandingachievement in 2013. In addition, this issue also
reports on two JSSC events in 2013: the Pacific
Structural Steel Conference (PSSC) in which thesteel construction-related organizations of 10
nations participated, and the 2013 JSSC
Symposium on Structural Steel Construction.

A special feature of this issue is a piece ontsunami countermeasures based on articles
published in JSSC No. 13, a steel construction
magazine published by JSSC for domestic use.
The Great East Japan Earthquake that occurredon March 11, 2011 caused severe earthquake
and tsunami damages. In order to make themost of the lessons learned from thesedisasters, various types of the latest tsunami
countermeasures are introduced under thetheme “Measures for Handling Giant Tsunamis”
that will be of help in structuring a society safe
from tsunami disasters.
The International Committee, while working on
multi-faceted responses to theinternationalization of steel construction
specifications and standards, promotes
exchanges of technical information andpersonnel between Japan and overseasorganizations. As one aspect of these
operations, we are attempting with this issue toinform our readers of JSSC operations, trends insteel construction, and the technologies andtechnological developments relevant to theplanning, design, and building of steel structuresin Japan.
If you wish to obtain more detailed information
about the various articles contained in this issue
or to receive related technical information, please
do not hesitate to contact info-jssc@jssc.or.jp.

Prize-winning works in JSSC’s commendations
for outstanding achievements
Assembly of thetower section ofTOKYO SKYTREE,
the world’s tallest
broadcasting tower
Shibuya Hikariebuilding, marked bydifferent
configurations in its
high- and low-rise
sections

Closed demolition of 140 m-high hotel
building, mainly featuring the mitigationof neighborhood anxiety

STEEL CONSTRUCTION TODAY & TOMORROW
Published jointly by

The Japan Iron and Steel Federation
3-2-10, Nihonbashi Kayabacho, Chuo-ku, Tokyo 103-0025, Japan
Phone: 81-3-3669-4815 Fax: 81-3-3667-0245
URL http://www.jisf.or.jp/en/index.html
Japanese Society of Steel Construction
Yotsuya Mitsubishi Bldg. 9th Fl., 3-2-1 Yotsuya, Shinjuku-ku, Tokyo 160-0004, Japan
Phone: 81-3-5919-1535 Fax: 81-3-5919-1536
URL http://www.jssc.or.jp/english/index.html

Kanayagou Viaduct, an expressway
bridge constructed using a new designconcept based on compact sections© 2014 The Japan Iron and Steel Federation
Edited byCommittee on Overseas Market Promotion, The Japan Iron and Steel Federation
Chairman (Editor): Tetsuya Akahoshi
P u b l i s h e d t h r e e t i m e s p e r y e a r, S T E E L C O N S T R U C T I O N TO D AY &TOMORROW is circulated to interested persons, companies and publicorganizations to promote a better understanding of steel products and theirapplication in the construction industry. Any part of this publication may be
reproduced with our permission. To download content (PDF format), please go
our website at: http://www.jisf.or.jp/en/activitity/sctt/index.html. We welcome yourcomments about the publication and ask that you contact us at: sunpou@jisf.or.jp.