No. 62 August 2021

STEEL CONSTRUCTIONTODAY & TOMORROW

https://www.jisf.or.jp/en/activity/sctt/index.html

Feature Article

Initiatives for Building
Resilient Foundation
Structures
1 Application of the Partial Factor Design Method forFoundations in the Japanese Specifications for Highway
Bridges

5 Revision of Recommendations for Design of Building

Foundations and Establishment of Secondary Design
Method for Steel Pipe Piles

9 Development of Seismic Retrofitting Technology for

Existing Bridge Abutment Foundations Using Large-scale
Shaking Table Test

11 Reformation Design of Existing Port and Harbor Steel

Structures-Effect of Modeling in Numerical Analysis of
Seismic Response

13 Performance of Steel Sheet Piles for the Stability of River
Embankment under Earthquakes

Special Topic:
Building a Society Resilient to Natural Disasters

15 Towards the Realization of Resilience Innovation for 2035

JISF Operations

19 2020 AJSI Webinar: Energy-Efficient and Environmental
Transition towards Sustainable Steel Industry

19 Technical Report of the Long-term Exposure Tests forConstruction Materials

Published Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel Construction

Feature Article: Initiatives for Building Resilient Foundation Structures (1)Application of the Partial Factor Design
Method for Foundations in the JapaneseSpecifications for Highway Bridges

by Toshiaki Nanazawa, Ministry of Land, Infrastructure, Transport and Tourism

Toshiaki Nanazawa: After finishing the master’s course
at the Graduate School of Engineering, Tohoku University,
he entered the Ministry of Construction in 1994. He worked
at the Center for Advanced Engineering Structural Assessment and Research, PWRI in 2010 and he assumed his
current position as Head, Foundation, Tunnel and Substructures Div. of National Institute for Land and InfrastructureManagement, MLIT in 2018. His specialized field is structural engineering and foundation engineering. Dr. Eng.

The Japanese Specifications for Highway
Bridges (JSHB) was revised in 2017. The
major revision in this latest version was
the introduction of the partial factor design method in the JSHB1).
Preceding the revision made in 2017,
the application of the partial factor design
method in the foundation design provided
in the JSHB was examined, the content of
which is introduced in this article.
Application of the Reliability
Design Method for Foundations in
the JSHBIn the literature2), the damage level was
judged of 401 bridges located in Sendai,
where strong seismic motions were observed from the 2011 Great East Japan
Earthquake. As a result of this judgement,
it was confirmed that, although the bridges in which damage occurred in the foundation numbered only three of the 401
bridges, large-scale damage occurred in
the foundations of all of these three bridges (Fig. 1).
Even when the level of bridge foundation damage from the above great earthquake is compared to damage caused byother earthquakes and scouring damage
caused by floods, the same trend can beobserved. Why is the number of damaged
existing bridge foundations constructed innonconformity with the latest JSHB few?
A main attributable reason for this is thatthese foundations maintained large safetymargin secured by the safety factors andother safety margins at the design stage.
Meanwhile, in the existing bridge foundations under certain conditions, enoughsafety margin provided in the design stage
could not be secured, which thus led to theoccurrence of bridge damage that exerted
an adverse social impact.
Photos 1 and 2 show examples of dam1 Steel Construction Today & Tomorrow August 2021

could not be prevented only by means ofreinforcement and improvement of prescriptions pertaining to design methods,
such as increase of design seismic mo-

age that occurred in the existing bridge
substructures. It was confirmed from theresults of analysis that the damage anddeformation of the bridge substructures

Fig. 1 Damage Sections and Damage Levels of the Bridges Damaged by the2011 Great East Japan Earthquake2)
Bridgepier: C
4%Superstructure(girder end): C
4%
A
2%
Foundation(pile bent)

Diagonal
member: B
2%

Box upper
slab: C
2%

B
4%

As: Bridge collapse due totsunamisAs
13%

A: Large-scale damage
B: Medium-scale damage

C
15%

Abutment

Bearing
supportB
17%

C: Small-scale damage
D: No damage

B
4%
C
33%
Photo 1 Bridge abutment that collapsed due tothe erosion of the slope

Photo 2 Bridge abutment that caused
subsidence due to the collapse of theslope during an earthquaketion, but that further reinforcement andimprovement of the prescriptions pertaining to the ground surveys and foundation construction methods were required
to prevent the damage and deformation.
However, because it is difficult to uniformly reinforce the currently-prevailingprescriptions pertaining to ground surveys
and foundation construction methods, it isdesirable to change to the design methods
that can yield a certain advantage by theuse of quantitatively and qualitatively appropriate ground surveys and highly-precise construction control technologies.
The application of the reliability design method, particularly the partial factor
design method, in design specifications
brings about high effectiveness, which issummarized in Table 1. As shown in (3) inTable 1, because partial factors conforming to the deviation of each element canbe settled, a partial factor design method
is likely to be established that can demonstrate advantages brought about by theuse of highly precise ground surveys andconstruction methods. However, it is necessary to pay due attention to the fact thatthe reliability theory can only be appliedin the range where significant statistics
are available and where the ease-of-understanding of the design method is prop-

erly considered for those engaged in practical design and construction.
Based on the above, the reliability isassessed using statistics relating to the differences in ground conditions and survey
methods and the differences in foundation
construction methods, and then the partial
factors that differ depending on the conditions are settled (refer to Fig. 2). Consequently, it has become possible to make

Table 1 Effectiveness Brought about by the Use of the Partial Factor Design Method
No. Effectiveness(1)

Keeping up with international trend(2)

Appropriate resources allocation to various bridge structures due to the arrangement of reliability(3)

Possible to settle the rational partial factor that conforms to the deviation of each element(4)

Promotion of the introduction of new structural materials and members(5)

Possible to reexamine the partial factors based on data

Fig. 2 Proposal of Partial Factor Design Method for Bridge Foundations with Consideration for the Uncertainty Involvedin Ground Surveys and Piling Work
[Analyzing foundation damages that occurred so far]Large-scale damage partly affecting the society⇒ Analysis of factors and necessity to provide appropriate measure [A]

Scope of damage is restrictive⇒ No shortage of safety factor in general [B][Analysis of damage factors] Measure for [A]No reaching to the supporting layer; Support to the layer that becomes instable during service⇒ Sure grasping of stable/unstable layer during ground survey and construction) [C1]
Insufficient survey and assessment for unstable ground⇒ Correct assessment (survey) of dynamical characteristics [C2][Measure by revising the JSHB] (Measure for [C])Need for reinforcement and improvement of ground survey/construction-related prescriptions
But, difficulty in uniform reinforcement of ground survey/construction-related prescriptions⇒ Conversion to the design method with which relative merits can be brought about
by reinforcing and improving ground survey and construction [D][Effectiveness brought about by the use of reliability design
method] (Measure for [D])Possibility to incorporate the reliability by assessing theuncertainty⇒ To the design method that takes into account thereliability of ground survey and construction [E][Tasks imposed on reliability design method]
Only the possibility to assess the reliability within the range wheredata is available
In the conventional design method, settlement of safety factors within
the range where data is not only available but also unavailable⇒ Based on the safety margin in the conventional design method (relative to [B]) [F]⇒ Application of the reliability in relative assessment due to the difference inconditions (relative to [D]) [G][Existing knowledge]
Properness of the partial factor design method due to its
applicability in practical design works [H][Proposal of the means to apply the reliability design method]
Proposal of the partial factor design method in which the partial factors differ depending on the ground survey and construction conditions(in place of uniform safety factors) (relative to [E, G, H])
Settlement of the reliability target based on the safety margin in the ground survey and construction that is applied as standard practice in theconventional design method (relative to [F])August 2021 Steel Construction Today & Tomorrow 2

more rational design by the use of higher
factor values when highly reliable groundsurvey and construction method are applied. Meanwhile, in Fig. 2, the symbol
shown in green is inserted so that the relation between the task and the corresponding measure can be understood.
Calculation of Partial Factors for
the Load-bearing Capacity Designof Pile Foundations
As an example of settling a partial factor, themethod to calculate the partial factors applied in verifying the yield bearing capacity
versus the axial-direction thrusting force ofpiles is shown3). In order to take into accountthe difference in uncertainties in the conditions of the resistance side such as structuraland ground conditions, the partial factor φrelating to the resistance is examined. In thisexamination, the uncertainty of the load is
not taken into account, and the load is treated as a deterministic value. In the assessment of the uncertainty of the ground resistance, the log-normal distribution is applied.
Equation (1) below shows the calculation of the limit value to be applied for retaining the axial-direction thrusting force ofpiles within the range of the yield bearing
capacity of the pile. The pile bearing capacity is verified by means of the comparison
between the limit value and the response
value to be calculated from the equation.
While Equation (1) conforms to the bearing
capacity calculation equation in the conventional design method1), the equation applies
the characteristic value of the yield bearing
capacity assumed to have a definite relation
with the ultimate bearing capacity of pile Ru.
(1)
where,
Rd: Limit value of axial-direction thrusting force of pile (kN)
φ: Partial factor

Ry: Characteristic value of yield bearing
capacity of pile (kN)
Ws: Effective weight of earth substitutedby pile (kN)
W: Effective weight of pile and earth inside pile (kN)
Because the response of the pile foundation changes depending on the structural and ground conditions, the uncertain statistic of the response value is calculated bymeans of the Monte Carlo simulation employing 114 cases of pile foundation models obtained by trial design under diverse
structural and ground conditions and basedon the conventional design method. On theoccasion of the simulation, the uncertainty
of both the axial spring constant of a pile Kv
and the coefficient of horizontal subgrade

Table 3 Statistics of Uncertainty of the Coefficient of Horizontal Subgrade Reaction KH
Case

Estimation method for kH or deformation modulus E0 used in
calculating kH

Case-1

When obtained from the horizontal loading test for pile

0.25

Case-2

When obtained by the standard penetration test as well as
the laboratory test or borehole horizontal loading test

0.45

Case-3

Sandy soil with N value of 5 or more

Case-4Case-5

Pile driving method

1.00

0.40

Cast-in-place pilemethod1.00

0.50

Bored pile method

1.00

0.45

Pre-boring pilemethod1.00

0.35

Steel pipe soil
cement pile method

1.00

0.30

Screw pile method

1.00

0.40

3 Steel Construction Today & Tomorrow August 2021

Coefficientof variation

1.0

0.60

Cohesive soil with N value of 5 or more

0.70

N value of less than 5

1.00

Pile installation method

Average

Coefficient of variation

Pile driving method

1.0

0.45

Cast-in-place pile method

1.0

0.40

Bored pile method

1.0

0.35

Pre-boring pile method

1.0

0.25

Steel pipe soil cement pile method

1.0

0.15

Screw pile method

1.0

0.20

Fig. 3 Reliability Index β for Pile Foundations Designed Employing theConventional Design Method

Level 1 seismic motion

2.0

Reliability index β

Average Coefficientof variation

When obtained only
from the standard
penetration test

Average

Table 4 Statistics of Uncertainty of the Vertical Bearing Capacity of Piles

Table 2 Statistics of Uncertainty of the
Axial Spring Constant of Pile KV
Pile installation
methodreaction kH are taken into account (Tables
2 and 3). In addition, the uncertainty of theresistance value is as shown in Table 4.
Of the calculation results for the reliability index β for the pile foundation, thecalculation result in the event of an earthquake that is predominant in pile foundation design is shown in Fig. 3. Based on
the reliability index β thus calculated, thereliability index βRT relating to the target
resistance of the pile foundation is settled.
In the settlement of the reliability index in the case of the difference in groundsurvey methods, the index β is basically settled that conforms to Case 2 that ismost commonly applied in the estimationof the ground deformation modulus (refer to Table 3). In the settlement of the re-× Case-1
Case-2Case-3Case-4Case-5

1.5
1.0
0.5
0.0

Steel
pipe soil Screw
cement pile
pile method
methodPile driving
methodBored pilemethodPile foundation modelPre-boring
pile method

Cast-in-placepilemethodliability index in the case of the differencein pile installation methods, when confirming the reliability index β in Case 2, theindex is divided into the following two
groups: a group of relatively small index(β=0.3~0.5) for the pile driving method,
cast-in-place pile method and bored pilemethod (referred to as conventional installation methods) and another group of relatively large index (β=0.7~0.14) for the
pre-boring pile method, steel pipe soil cement pile method and screw pile method(referred to as the new installation method).
The reason why the index β of the new installation method becomes larger than thatof the conventional method is considered
to be attributable to upgrading of the installation control method in recently-developed new installation methods, and as a result it has become possible to implement
highly-precise installation work.
Settling β of the conventional installation method in Case 2 as the basic value
and taking into account the improvementin estimation accuracy brought about by
the reexamination of the bearing capacity
estimation equation and the deviation due
to the difference in ground and pile installation conditions, the reliability index βRT
relating to the target pile foundation resistance is settled at 0.50.
Then, the partial factor φ at the resistance side, which conforms to βRT, is calculated. Regarding the yield bearing capacityof the pile subjected to the axial-direction
thrusting force, the effect of the differencein the installation method on the yield bearing capacity is more predominant than thatof the estimation accuracy for the groundreaction force coefficient on the yield bearing capacity. Table 5 shows the partial factor φ that conforms to the difference in the
installation method. Table 5 also shows theaverage φ value of the conventional installation method, used as the standard value insettling the reliability index βRT.
Meanwhile, due attention should be paid
to ensuring that the calculation results shown
Table 5 Partial Factor Φ by Pile
Installation Method
Pile installation methodΦPile driving method

0.71

Cast-in-place pile method

0.74

Bored pile method0.77

Pre-boring pile method

0.82

Steel pipe soil cement pilemethod0.88

Screw pile method

0.85

0.74
(averagevalue)

in the above are not identical with those in
the final content of the revised JSHB.
Partial Factor Design Method for
the Rationalized Design ofFoundations
In the conventional design method for bridgefoundations, the uniform safety factors havebasically been applied. In contrast, the partial factors that differ depending on the pile
installation and ground survey methods
can be settled by employing the partial factor design method introduced above, which
thus allows for securing identical reliability in foundation design regardless of the difference in estimation accuracy. In addition,
when highly precise installation and groundsurvey methods are applied, it will become
possible to perform rationalized design, andtherefore the application of highly precise
installation and ground survey methods are
expected to be further promoted.
On top of this, the dissemination of thecontent shown in this article will bring aboutsuch merits-in cases when more highlyprecise ground survey and pile installation
technologies are developed, it will be possible to settle partial factors that are more advantageous in terms of design compared tocurrent levels, and as a result new possibilities for making more rationalized design
will be recognized by those engaged in thedevelopment of new technologies that target
further improvement of technologies. As aneffect induced by these attempts, it is expected for the reliability improvement cycle toattain steady development (refer to Fig. 4).

References
1) Japan Road Association: Specificationsfor Highway Bridges, Part 4 Substructures, JRA (2012), 2012
2) K. Inazumi and J. Hoshikuma: Trend
Analysis of Damage to Bridges in Sendai City due to the 2011 Great East Japan Earthquake, Proceeding of the Society of Civil Engineers A1 (Structureand Seismic Engineering), Vol. 71, No.
4, pp. 1923-1929, 20153) T. Nanazawa, T. Kouno, K. Miyahara and I. Oshiro: Research on the Revision of the Estimation Design Equations for the Vertical Bearing Capacity of
the Pile Foundation and Ground Spring
Constant and on the Evaluation of Reliability, Technical, Note of PWRI, No.
4374, 2018

Fig. 4 Cycle for the Technical Development and Estimation Accuracy Improvement
Mainly Targeting the Settlement of Reliability-based Partial Factors

Additionally-

Reflection in the JSHB the partial factors thattake into account the difference in the reliability(accuracy) in various ground survey andconstruction methods

Reliability assessment and partial
factor proposal in the case of applying
a new or improved technology

Accumulation and analysis ofdata by means of testing in thecase of applying a new or improved
technology

Dissemination of the factors in which the improved
accuracy of ground survey and construction
methods leads to an advantage in terms of design

Development of new technology
or improvement of existing
technology with the target placedon the improvement of accuracy

Further rationalization in design and further improvement of realiability
August 2021 Steel Construction Today & Tomorrow 4

Feature Article: Initiatives for Building Resilient Foundation Structures (2)Revision of Recommendations for
Design of Building Foundations andEstablishment of Secondary Design
Method for Steel Pipe Piles

by Katsuichiro Hijikata, Former Professor at Shibaura Institute of Technology

Katsuichiro Hijikata: After graduatingfrom the School of Engineering, The
University of Tokyo, he entered Tokyo
Electric Power Company in 1981.
Then he was appointed to Professor, School of Architecture, Shibaura
Institute of Technology in 2013. Heresigned his post as professor in 2021.

The revised version of the Recommendations for Design of Building Foundations
was published by the Architectural Institute of Japan in November 2019 (herein
after referred to as the “new Recommendations”). This article explains the new
Recommendations focusing mainly onseismic resistance-related prescriptions
for the pile foundation structures provided in the new Recommendations.
Further, because the secondary design
method for building foundations was
newly prescribed in the new Recommendations, this article explains the current
state of the secondary design method forsteel pipe piles being established.
Outline of New Recommendations• Major Revisions in New Recommendations
The major revisions provided in the new
Recommendations are shown below:-It was shown as basic policy that theperformance-based design (secondary
design) for level 2 seismic motion bemade for the foundation structure.
-The design limit value and the required performance, which are applied to verify safety, were made clear
as thoroughly as possible. In addition,
the performance grade (safety level)of foundation structures that takes into account the importance of respective buildings was proposed.
-In order to promote the practical use of
the secondary design, the seismic load
and the ground deformation occurringin the event of earthquakes were prescribed. In addition, the “group pile
5 Steel Construction Today & Tomorrow August 2021

frame model” was proposed as thecalculation method for foundation
structures.

• Necessity of Secondary Design

for Foundations Structures
In the Building Standard Law of Japan,
while the prescription of the secondary
design for superstructures is provided,that for foundation structures is not provided. Only the prescription-“the foundation structure can be designed only by
the use of allowable stress calculation(primary design)”-is provided in Notification No. 1347-2 of the then Ministryof Construction.
The reason why secondary design
is not required in designing foundation
structures is considered to be attributable
to the fact that there have been no examples in Japan in which the collapse or inclination of foundation structures havedirectly affected human lives. However, the necessity of secondary design offoundation structures has been strongly
recognized in recent years due to the following:-In past earthquake damages, there
were many cases in which difficult
tasks and huge expenses were required for the recovery and repair ofdamaged foundation structures. As
a result, it has been recognized to benecessary from the viewpoint of asset
protection to perform design that can
avoid great foundation damage fromoccurring.
-There exist both private and public
important buildings that will requirecontinued usage after earthquakes,
and thus it has been desired from theviewpoint of business continuity totake proper countermeasures against
level 2 seismic motion that occurs extremely rarely.
Based on the above trends, the Architectural Institute of Japan decided toclearly show the secondary design forfoundation structures in the new Recommendations, preceding the BuildingStandard Law of Japan.

• Specific Revision Contents

The content of specific revisions pertaining to the secondary design of foundation structures shown in the new Recommendations are introduced below:-Marginal state value and required performance for design
In the new Recommendations, threemarginal states were defined, andthe required performance that corresponds to these three marginal states
were prescribed. Tables 1 and 2 show
their specific contents. The figure on
the right in Fig. 1 shows the examination items used to confirm the required performance pertaining to pilefoundations.
-Seismic load for design
In the new Recommendations, theseismic load due to level 2 seismic
motion, which works on the pile foundation, was prescribed as shown in the
figure on the left in Fig. 1. Of theseseismic loads, the inertia force andoverturning moment of superstructure were prescribed using the exist-

Table 1 Definition of Marginal States of Foundations
MarginalstatesDefinition

Usage
limit state

A state in which the superstructure begins to have inadequate usability due tosubsidence and displacement of the ground and foundation members.

Damagelimit state

A state in which repair/reinforcement of the superstructure or foundation member
begins to be required due to subsidence/deformation of the ground/foundation member.

Ultimate
limit state

A state in which the superstructure cannot be supported due to destruction ordeformation of the ground/foundation member, or a state in which repair/reinforcementof the foundation member begins to become extremely difficult.

Table 2 Required Performances for Marginal States
Marginalstates

Impact on superstructure

Foundation

Usage
limit state

There is no problem withusability and durability.

There is no problem with No harmful subsidence or
durability.
deformation occurs during
No harmful cracks occur. use.

Damagelimit state

Does not cause excessive
inclination or damage that
requires structural
repair/reinforcement.

No damage that requires Excessive subsidence andstructural repair or
residual deformation do notreinforcement.
occur.

Does not fall or collapse

Does not cause brittle
fracture. In addition, thelimit of deformation
performance is reachedand the yield strength is
not reduced.

Ultimate
limit state

GroundThe ground(improved ground) does not
lose its normal force

Fig. 1 Examination Items and Seismic Loads for Confirming Required
Performances
Overturning momentof superstructure<Impact on superstructure>
Deformation angle and inclination angle of foundation<Foundation
member>Stress of eachmember, etc.

Earthpressure
springInertial force ofsuperstructure

Ground displacement
Load to consider<Pile or ground>Pull-out
resistanceing evaluation equations in the Building Standard Law of Japan and otherguidelines. As regards the ground displacement and the earth pressure
spring, a simple evaluation equation
having a form that does not need detailed analysis was newly prescribed.

<Pile or ground>
Vertical bearing capacity,
subsidence amount-Calculation method for stress working
on pilesIn the new Recommendations, in order to calculate the stress working on
piles, the “group pile frame model”
was proposed (refer to Fig. 2). This
analysis method is a static analysis

model in which the seismic motion
is substituted for the equivalent seismic load, and incremental analysis iscarried out by taking into account thenonlinearity of the ground and pile. In
the analysis, one row of group piles
is taken out, and incremental analysis
is carried out using this row as a twodimensional model (row pile model). The pile circumferential ground issubstituted for the equivalent horizontal ground spring, and the ground displacement is input via the horizontal
ground spring (response displacement
method). Further, the foundation slab
is set as rigid, and the condition of pile
tip is horizontal roller in which the subsidence of the pile tip is not allowed.
Future Tasks Involved in Secondary Design Method for Steel Pipe
Piles
The secondary design method for foundation structures was shown in the new
Recommendations. However, in order topromote the practical calculation of thesecondary design method targeting steel
pipe piles, the following three tasks remain to be solved:-As regards the M-φ relationship ofsteel pipe piles, its revision is underway at the Architectural Institute ofJapan, and thus it will be necessary tostart a regular discussion on the M-φrelationship after grasping the revision
results. More specifically, in order topromote regular discussion, it will benecessary to follow the Strength andDeformation Capacity of Foundation
Members planned to be published infiscal 2021.
-While the calculation method for thepile stress of group pile frame model
has been shown, the specific analysis
code has not yet been prepared.
-The effect of secondary design on steel
pipe piles has not yet been grasped.
As regards the first task, the review isunderway at the Architectural Institute ofJapan, which is proceeding as scheduled.
As regards the second and third tasks,
the Research Working Group on the Secondary Design of Steel Pipe Pile Foundations was established within the Japanese Society of Steel Construction in
2019, where examinations are underway.

• Improvement of Group Pile

Frame Model
The analysis program exclusively used
August 2021 Steel Construction Today & Tomorrow 6

Fig. 2 Overview of Group Pile Frame Model
Overturning
moment ofsuperstructure

Inertial force ofsuperstructure

Constant axial
force+axial
force during
an earthquake
Pile
circumference
groundspringGround displacement

Horizontal roller

Fig. 3 Analysis Conditions
Inertial force in level 2

31.2 mGround displacement in level 2

4.8 m

Vs=100 m/s

Vs=300 m/s
2.4 m
D=600 mm，t=10 mm

for the group pile frame model proposedin the new Recommendations and incommon use has not yet been prepared,
and improvement has been called for.
To cope with such a situation, the Hijikata Laboratory of the Shibaura Institute of Technology has developed a calculation code (Group Pile EASY-PILE)
for use for the group pile frame model.
This code has been developed based on
the original program of the Hijikata Laboratory, to which diverse functions havebeen added.
7 Steel Construction Today & Tomorrow August 2021

Pile number

The code has been subjected to verification by the Research Working Groupand has been made open free of charge
since October 2019. The code is readyfor use by everyone.

• Grasping the Effect of Second-ary Design on Pile Foundations
While the application of secondary design has not been required for the designof pile foundations in Japan, secondary
design has been applied in the construction of important buildings as the needarises. In conventional secondary design, the ultimate state of piles is commonly evaluated by the use of the ultimate strength, and the pile head plastic
hinge that can be allowed to be formedin the group pile has been limited in one
place. On the other hand, in the new Recommendations, it is prescribed that theultimate state of steel pipe piles can beevaluated even by the use of ultimate deformation, and thus it has become possible to form the plastic hinge at multiple
places on the pile heads of group piles.
However, examples of calculations
employing the group pile frame model
proposed in the new Recommendations
are less available, and examples of examinations in which the pile structure
is evaluated by the use of ultimate deformation are also less available. Givensuch a situation, the Research Working
Group has promoted stress calculations
pertaining to steel pipe piles under various conditions to accumulate related
knowledge. Examples of examination results by the Research Working Group are
introduced below:
Fig. 3 shows example of examination results targeting group piles. Table
3 shows the specification of steel pipe
piles used in the examination, and Table
4 the ground conditions. In the examination, the constant load working on one
pile was set at 627.5 kN, the design inertia force working on the fifth row of piles
1,500 kN, and the design overturning
moment 32,500 kN. The M-φ relationship (moment curvature) of steel pipe
piles was settled in conformity with the
Recommendations for Plastic Design ofSteel Structures of the Architectural Institute of Japan. The calculation was carried out up to the stage of surpassing thedesign load, and the point where a certain pile of steel pipe piles reached thelimit deformation (limit curvature in thisoccasion) was set as the end point, andthen the horizontal strength of the pileslab at this end point was calculated.
Fig. 4 shows the M-φ relationship of
the pile head in the limit state, and Fig. 5
the hinge formation state. As seen in the
figures, when the steel pipe pile is evaluated in terms of limit deformation, plural hinges are formed on the pile head,
and as a result it was confirmed that thehorizontal strength of the foundationslab was increased by 36% compared tothe case in which the pile is evaluated interms of limit strength (the hinge is allowed to form at one point).

Table 3 Specifications of Steel Pipe Piles
LengthDiameterThickness

Yield stress

Young'smodulus36 m

600 mm10 mm(same for each position)

357.5
N/mm2

205000N/mm2

Pile spacing ratio
4.0

Table 4 Ground Conditions Used for Analysis
Condition

Surface ground

Deep ground

Ground characteristics:

Sandy ground

Sandy groundDepth

0~31.2 m

31.2~36 m

Unit volume mass

1.8×10 kg/m

1.8×103 kg/m3

Friction angle

21.3°

46.6°

Shear wave velocity

100 m/s

300 m/s

Poisson's ratio

0.33

0.33

3

3

Fig. 4 M- Φ Relationship of Pile Heads

Refined Secondary Design
MethodIn this article, the revision content of the
Recommendations for Design of Building Foundations was introduced. Further, examples of trial calculation for thesecondary design method for steel pipe
piles were shown. In the trial calculation,
it was confirmed that, when steel pipe
piles are evaluated in terms of limit deformation (limit curvature), the strengthis significantly increased compared tothe case in which the strength is evaluated by the use of the existing calculation
method and that the design and application of steel pipe piles can be expected to
be rationalized.
Expectations are high for the steadybrush-up of the secondary design method for steel pipe piles so as to surely establish the secondary design method forsteel pipe piles.

1400

Bending momennt (kNm)

1200
1000
800
Pile 5 reaches limit curvature

600
400

●：Analysis end point

200
0▲：Limit curvature

0

0.01

0.02

0.03

1_1

1_2

1_3

0.04

0.05
0.06
Curvature (1/m)

1_4

1_5

Fig. 5 Hinge Formation State
1184 kN

1516 kN

1608 kN

Hinge
Pile 5 reaches
limit curvature

August 2021 Steel Construction Today & Tomorrow 8

Feature Article: Initiatives for Building Resilient Foundation Structures (3)Development of Seismic Retrofitting
Technology for Existing Bridge
Abutment Foundations Using LargeScale Shaking Table Testby Michio Ohsumi and Yong Yang, Public Works Research InstituteMichio Ohsumi: After completing the master’scourse at the Graduate School of Engineering,
The University of Tokyo, he entered the Ministry ofConstruction in 1996. He currently serves as Chief
Researcher at the Center for Advanced Engineering
Structural Assessment and Research, Public Works
Research Institute. His specialized field is seismic engineering.

9 Steel Construction Today & Tomorrow August 2021

• Seismic Retrofitting Effect

Under the seismic ground motion (2-I-I3)4) with amplitude-adjusted waves observed in the Tohoku earthquake, themaximum response of tensile strain ofexisting piles and steel pipes is shown in
Fig. 3. In the model 1 without retrofitting, the maximum tensile strain of the
middle and front existing piles at theFig. 1 Proposal of
Fig. 2 Outline of Experiment Models (unit: mm)!"#$%:%;2-1-6<*%-.%!"#$%&%'()*"+,%-.%/01,2"3,+)%4-5,*6%7(+")8%339
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Shaking Table Test with 1/4.5
Scale• Bridge Abutment Models
The retrofitting method shown in Fig.1
was adopted in the shaking table test.

steel pipes used for sheet pile wall in themodel 2 had a diameter of 100 mm. As
shown in Fig. 2(b), the filling layer had athickness of 1780 mm and the liquefiable
layer had a thickness of 2200 mm.
Photo 1 shows the shaking table withnickname ‘E-Defense’, which is owned
by National Research Institute for Earth
Science and Disaster Resilience (NIED).
The soil tank was set on the shaking table.

This proposal was made through joint research with the Japanese Association for
Steel Pile Piles (JASPP). This retrofitting method can avoid traffic hindrance
because the retrofitting work is only carried out at the side of bridge abutment.
For the steel pipe sheet pile wall used inthis retrofitting method, the retrofitting
difficulty is expected to be decreased, especially in the case when the heavy construction machine cannot be used due tonarrow construction yard.
Fig. 2 shows the outline of experiment models with 1/4.5 scale. As shownin Fig. 2(a), model 1 (without retrofitting) and model 2 (with retrofitting) were
set in the same soil tank. Model 1 wasdesigned according to the former standard3). The existing piles of two models
were made of reinforced concrete material with a diameter of 101.6 mm. The<=>>;;>> 9AB>

Toward Highly Resilient Highway
Networks
Ground liquefaction can cause the lateralflow acting on the bridge foundations. In
the Kobe earthquake in 1995, it was confirmed that the liquefaction lateral flow
could lead to destructive damage to existing bridge structures. It is necessary
to develop the seismic retrofitting technology for existing bridges located onliquefiable ground to improve the highway network resilience. To attain thisgoal, at the Center for Advanced Engineering Structural Assessment and Research (CAESAR) of the Public Works
Research Institute, the experimental researches had been carried out from 2014
to 2019.
In the first series of experiment research, the dynamic centrifuge test with
1/60 scale1) was conducted. In the second series, the shaking table test with
1/10 scale2) was conducted. In the third
series, the shaking table test with 1/4.5
scale was carried out.
This article describes the result of theseismic retrofitting effect of the largescale shaking table test in the third series of experiment. In addition, the estimating model of the earth pressure due
to liquefaction established based on theseries of experiment results, which is theimportant consideration issue in the retrofitting design of existing bridges, is also introduced.

Yong Yang: After completing the doctor’s course at the Graduate School ofEngineering, The University of Tokyo,
he served as Project Researcher from2016 to 2017, Institute of Industrial Science, The University of Tokyo. He currently serves as Research Specialist at
the Public Works Research Institute.

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front side was obviously more than yieldstrain. However, in the model 2 with retrofitting, the maximum tensile strain of
the middle and front existing piles was
obviously decreased at the depth about
2 m and the maximum tensile strain of
the middle existing pile was less thanyield strain. The maximum tensile strainof steel pipes of sheet pile wall was lessthan yield strain, showing that the sheet
pile wall can remain in elastic status toprovide enough capacity.
Further information about the experimental results can be found in the reference5).
Estimating Model of Earth
Pressure
The earth pressure (EP) acting on thepile foundation in the liquefiable layer
is modeled as EP=C1·C2·C3·q. The parameter q is the overburden pressure due
to filling layer. The coefficients C1, C2,
and C3 are for the effect of depth, pile arrangement, and ground liquefaction, respectively.

• Coefficient for the Depth Effect(C1)
To accurately evaluate the earth pressure
due to liquefiable ground, the coefficient
C1 is set to reflect the distribution character of earth pressure on pile. As shown in

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Fig. 4, when the ratio x of the depth to thepile length is equal to 0, the result of C1 ismore than 0, meaning the earth pressure
occurring at the pile top; when x is equal
to parameter α, C1 is equal to 1, corresponding to the maximum of earth pressure; when x is equal to 1, C1 is equal to0, meaning there is no earth pressure occurring at the pile bottom.
The parameter α calculated by fitting
the results of three series of the experiments is 0.35.

• Coefficient for the Pile Arrange-

ment Effect (C2)
It was measured that the earth pressure
on pile at the back side of abutment was
obviously more than that of other piles.
Thus, the coefficient C2 is introduced
to consider the pile arrangement effect.
As shown in Fig. 5, the areas A0 and A1~3
mean the magnitude of the earth pressure
on piles. The coefficient C2 is defined as
the ratio of these areas of piles in pilegroup to that of single pile.

• Coefficient for the Liquefaction

Level Effect (C3)The earth pressure also depends on theliquefaction level. The coefficient C3 isintroduced to reflect the liquefaction level effect. As shown in Fig. 6, C3 is effective when the liquefaction level index FL

is less than 1.
By fitting the experimental results, theparameters A and B in the formula of C3
were obtained 1.0 and 2.0, respectively.
Further information about the evaluation model of the earth pressure due toliquefaction can be found in the reference6).

♦♦♦

The authors hope that the above research achievements related to the seismic retrofitting technology for existingbridge can contribute to build the resilient highway network to reduce theearthquake-induced loss in the future.
Acknowledgment
The research had been supported byCouncil for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program(SIP), “Enhancement of societal resiliency against natural disasters” (Funding agency: JST). We offer our thanks tothose of the Council for Science, Technology and Innovation who had supported this research project.
References
1) Y. Yang et al: Centrifuge modeling forseismic retrofit evaluation of bridge abutment pile foundation in liquefied ground,the 40th JSCE earthquake engineering
symposium, 2020 (In Japanese)
2) T. Nanazawa et al: Prevention of liquefaction-induced damage to existingbridges, Steel Construction Today & Tomorrow, N0.51, pp.4-6,2017
3) Japan Road Association: Design of Pile
Foundations-Guidelines to Design of Substructures of Highway Bridges, Mar. 1964
(In Japanese)
4)Japan Road Association: Design Specifications for Highway Bridges, Part V:
Seismic Design, Nov. 2017 (In Japanese)5) M. Ohsumi et al: Development of a seismic-performance assessment method andretrofitting technology against the liquefaction of existing bridges, Journal ofDisaster Research, vol.14, pp.269-278,
20196) Y. Yang et al: Estimating model of earthpressure on piles of bridge abutment foundation located on liquefiable ground andits verification analysis, Proceedings ofthe 22nd Symposium on Performancebased Seismic Design Method for Bridges, July, 2019 (In Japanese)

August 2021 Steel Construction Today & Tomorrow 10

Feature Article: Initiatives for Building Resilient Foundation Structures (4)Reformation Design of Existing Port andHarbor Steel Structures-Effect of Modeling in Numerical Analysis of Seismic Response-by Eiji Kohama, National Institute of Maritime, Port and Aviation Technology

Eiji Kohama: After finishing the doctoral course at theFaculty of Engineering, Graduate School of Hokkaido University, he entered Port and Harbor Research Institute of
the Ministry of Transport in 2000, and then served as seniorresearcher at the Port and Airport Research Institute. He
assumed his current position as head at Earthquake andStructural Dynamics Group, National Institute of Maritime,
Port and Aviation Technology in 2016. His specialized fieldis geotechnical earthquake engineering.

A study was made noticing the reformation design of port and harbor structuresby means of new installation of steel sheet
piles in front of the existing sheet pile
quay wall with vertical pile anchorage.
As regards the reformation design, it isaccepted as a safety-side design that theexisting structure is not taken into accountat the stage of analysis but that analysis
is made by means of modeling only the
newly-installed structure, and as a result
design employing such analysis methods is increasingly being applied. Meanwhile, in respect to this, some concerns
arise-the safety side in design may be
excessively assessed and there are many
unclear aspects involved in the original
construction process of existing structures
and the effect of the subsequent reformation process on existing structures.
Then, examinations were made of theeffect of the difference in dealing withexisting structures in the event of analysis on the seismic response analysis
result, employing a 2D FEM effective
stress analysis program (FLIP).
Seismic Response Analysis
Fig. 1 shows the quay targeted for seismic
response analysis. Fig. 2 shows the construction of the existing sheet pile quay
wall with vertical pile anchorage and subsequent reformation processes to increase
the quay depth by the use of sheet pile
structure with coupled-pile anchorage.
Processes 1-3 shown in the figure cover
the construction process for the existing
quay structure, and processes 4-7 show
the process to increase the quay depth by
the use of the new sheet pile structure.
In order to examine the effect of theexisting structure and the subsequent
reformation process on the seismic response analysis, a comparison study was
made by means of modeling of three cas11 Steel Construction Today & Tomorrow August 2021

was about half that in Case 1 where thees shown in Table 1.
existing sheet pile structure was ignored
In
Case
2,
the
seismic
responsewasana•lyzed by taking into account both the ex- and in Case 3 where the existing strucisting sheet pile quay and the new sheet ture installation process was ignored, andpile structure and all the processes shown further the residual displacement in Casein Fig. 2 in the dead weight analysis pri- 1 was nearly similar to that in Case 3 (Table 2). The bending moment of newlyor to the seismic response analysis.
installed sheet pile in Case 2 was largIn
Case
3,
the
seismic
responsewasana•lyzed by taking into account the existing er than those in Cases 1 and 3, and the
sheet pile quay but by taking into account bending moment in Case 1 was nearly
only the process to construct the new pile similar to that in Case 3 (Fig. 5).
structure in the dead weight analysis, andanalysis was made assuming the simulta- Useful Knowledge forneous installation of both the existing and Reformation Design
new sheet pile structures (refer to Fig. 3). When noticing the ending point of the deadIn
• Case 1, the seis- Fig. 1 Quay Targeted for Study
mic response was
Apron width
analyzed by igCrane span
Newly-installed
tie rod (HT450)
noring the existing sheet pile quay
structure, by taking
into account only
the new sheet pile
Tie rod
Steel sheet
structure installaExisting
pile (SY295)
water depthtion process evenpipe sheet
in the dead weight Steelpile (SKY490)
Steel pipe sheet pile (SKY400)
analysis that simuSteel pipe
lates the reformation New
water depth
pile (SKK400)
process, and without taking into acSteel
Crane
count the existing
pipe pile (SKK400)
foundation
sheet pile structure.
Fig. 4 shows theresults of seismic
Existing
response analysis
structure
employing
input
Newly-installed
structure
seismic motions.
As a result, the reTable 1 Modeling Cases
sidual displacement
Process
Case Modelingin Case 2 where
1 Modeling only of newly-installed sheet pile structure
4
both the existing7
2 Modeling of newly-installed and existing sheet pile
sheet pile structure
structures; Construction process is taken into accountand the new sheet
4
3 Modeling of newly-installed and existing sheet pile
structures; Existing sheet pile structure construction
pile structure areprocess is not taken into accounttaken into accountweight analysis prior to the seismic response analysis, the tension force working
on the newly-installed tie rod was smallin Case 2, and the tension force in Case
1 was nearly similar to that in Case 3 (Table 3). Further, the distribution of the maximum shear strain in Case 1 resembled thatin Case 3, and their distribution trend differed from the trend in Case 2 (Fig. 6).
Therefore, the seismic response analysis results in Case 3 where the existing pile structure was ignored were sim-

ilar to those in Case 1 where the existing
structure installation was ignored, and it
is considered that the tension force basically did not work on the existing pile
structure and that the existing sheet pile
structure basically did not contribute to
the behavior of new pile structure during
working of seismic motions in Case 3.
In the case of reforming an existing
sheet pile quay wall to a new sheet pile
quay wall, the following fact has become
clear from this study-in modelling not

Fig. 2 Processes to Reform Existing Quay (Processes
Taken into Account in Dead Weight Analysis andSeismic Response Analysis in Case 2)
Process 1

Dead weight analysis oforiginal ground andreclaimed soil
Process 2

Release of reaction force
of existing sheet pile
Process 3

Stress release by means of
excavation in front of existing
sheet pile structure to theexisting water depth

Process 4

only the new structure but also the existing structure, in cases when detailed
construction processes are not taken into
account, it is impossible to estimate theeffect of the existing structure on the reformed structure.
Reference
1) Iai, S., Matsunaga, Y. and Kameoka, T.:
Strain space plasticity model for cyclic
mobility, Soils and Foundations, Vol.
32, No. 2, pp. 1-15, 1992.

Fig. 3 Elimination of Existing Quay Construction Process(Processes Taken into Account in Dead Weight
Analysis and Seismic Response Analysis in Case 3)
Process 1

Installation of new steel pipe
sheet pile and input of fillingmaterials between existing andnew sheet pile structures
Process 5

Process 3

Release of stress by means of
excavation in front of
new sheet pile structure

Analysis of dead weightof original ground
Process 2

Release of reaction force of
newly-installed steel pipe
sheet pile
Process 6

Process 4

Analysis of dead weight ofreclaimed soil

Seismic response analysis

Table 3 Tension Force Working on Tie Rod at the Dead
Weight Analysis Ending Stage

Stress release by means of
excavation in front of new
sheet pile structure to the
new water depth
Process 7

Case
1
2
3

Tension force working
on new tie rod
405.0 kN
117.1 kN
351.7 kN

Tension force working on
existing tie rod
132.9 kN29.2 kN

Fig. 5 Distribution of Bending Moment in
Newly-installed Steel Pipe Sheet Pile
5

Seismic response analysis

0-5Residual displacement at Pile Crest
1,372 mm
738 mm
1,353 mm

600
400
200
0
-200
-400
-600
0

-10
Elevation (m)

Case
1
2
3

Fig. 4 Input Seismic Motion
Acceleration (Gal)

Table 2 Residual Displacement of
Sheet Piles in Seismic
Response Analysis

50

100 150 200
Time (sec)

250 300

Fig. 6 Distribution of Maximum Shear Strain γmax
(at the Dead Weight Analysis Ending Stage)
Case 1

Distribution of residual value γ

Case 2Distribution of residual value γ

-15
-20
-25
-30

Case 3Distribution of residual value γ

-35
-40
5000

Case 1 residual value

Case 1 maximum value
Case 2 residual value

Case 2 maximum value
Case 3 residual value

Case 3 maximum value
2500

0

-2500

-5000

Bending moment (kN・m/m)August 2021 Steel Construction Today & Tomorrow 12

Feature Article: Initiatives for Building Resilient Foundation Structure (5)Performance of Steel Sheet Piles for the
Stability of River Embankments under
Earthquakes

by Jun Otani, Professor, Kumamoto University and Kiyonobu Kasama, Associate Professor,
Kyushu University
Jun Otani: He is Trustee and Vice President
at Kumamoto University. He served as research fellow at Scrips Institute of Oceanography, University of California, USA in 1987
and received Ph.D at University of Houston,
USA (Civil Engineering) in 1990. His research
fields cover soil mechanics, geotechnical engineering and application of X-ray CT.

Introduction
Steel sheet piles have been used mainly for the purpose of temporary works
such as excavation and pre-construction
structures. However, recently those application fields have been expanded tothe permanent structures such as foundations. PFS (Partial Floating Sheet pile)method as shown in Fig. 1 is the one ofthis technique which was originally developed as the countermeasure methods for subsidence of surrounding soft
ground due to river embankment constructions.
Recently more wide application fields
have been expected for the steel sheet
pile method and this is the objective ofTechnical Committee (TC) under the International Press-in Association. In thisarticle, the activities of the WG (Working Group No.1 chaired by Prof. Kasama) in the TC which is the performanceof the steel sheet piles under 2016 Kumamoto Earthquake in Japan are briefly summarized.
Steel Sheet Piles at the Site
Fig. 2 shows the location and purpose of
the steel sheet pile construction method
Fig. 1 PFS Method

Fig. 12#*$%$*$
2 Location of Steel Sheet Pile Method
12#*$%$*$!"#$%&'&$!"#$%&'&$($'&)$*$($'&)$*$

3#)2045$6%
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Bearing stratum!"""""" #""Floating sheet pile12#*$%$*$
12#*$%$*$!"#$%&'&$!"#$%&'&$"#9&"'#,&

13 Steel Construction Today & Tomorrow August 2021$"""""""%"""""""&"'($"""""""%"""""""&"'(!"#$%&'()*+$),$-)&./+'0+"*&'+*(a) Purpose of countermeasures!"#$%&'()*+$),$-)&./+'0+"*&'+*($'&)$*$($'&)$*$"#9&"'#,&:&;045$6%+#,-"#
768$6,4'#,&%$*$:&;045$6%+#,-"#"#9&"'#,&
768$6,4'#,&%$*$End bearing
sheet pile!"##$"%"&#!"##$"%"&#!")*%)+!")*%)+!"##$"%"&#'('!")*%)+.$/$0-)$*$!"##$"%"&#'('!")*%)+!,-."'/.-#"+#)-&.$/$0-)$*$!,-."'/.-#"+#)-&!""/01"!""/01"!"""""" #""3#)2045$6%
768$6,4'#,&3#)2045$6%"#9&"'#,&
768$6,4'#,&

Soft groundKiyonobu Kasama: He is an associate professor at the department of civil engineering,
Kyushu university. He holds Ph.D from Kyushu
University, where he has been teaching andconducting research for 20 years. He received
the Outstanding Paper Award for Young Researchers of the Japanese Geotechnical Society and the society of material science.

.$/$0-)$*$.$/$0-)$*$,#$%&'()*,#$%&'()*!"#$%&'()*!"#$%&'()*"+ %&'()*"+-.)/0*$1%2.)3&%&0'%&'()*-.)/0*$1%2.)3&%&0'4)$5)/0'&.%&67/.&
4)$5)/0'&.%&67/.&!"""""" #""!"""""" #""(b) Type of steel sheet pile method$"""""""%"""""""&"'($"""""""%"""""""&"'(!1#$23(+$),$*/++4$*5++/$(64+$0+/5)7!1#$23(+$),$*/++4$*5++/$(64+$0+/5)7!"#$%& '()*+"(,%(-%.+//0%.1//+%2"0/%3/+1(4in the Kumamoto Plain, Japan. This area
is located at Kumamoto Prefecture in the
middle of Kyushu Island. There are twomain rivers called Shira River and Midori River including two sub-rivers called
Kase River and Hamatogawa River. In
this figure, the left and right sides of theriver are indicated in two colors, respectively, and the color of the side near thebank indicates the front side of the river(outside of the bank) and the side farther
from the bank indicates the back side of
the river (inside of the bank).
In Shirakawa River, the inner side ofthe embankment near the house was reinforced for the purpose of only subsidence or both subsidence and earthquake
resistance, while the outer side of the embankment was reinforced only for earthquake resistance. A reinforcement of theembankment was carried out on the innerside of the Midori and Hamato Rivers toprevent subsidence, and on the outer sideof the embankment, reinforcement of theembankment was carried out for the purpose of constructing a revetment using
earthquake resistance measures or sheet
pile method. Most of the river embankments were reinforced by the PFS andFL (floating sheet pile) methods on the
inner and outer sides of the embankment,
respectively.

Table 1 shows the statistics of the
sheet pile lengths used for each methodin the rivers. The column of PFS methodin this table shows the sheet pile lengths
of both end bearing and floating sheet
piles used and their sheet pile length ratios. The average sheet pile lengths forend bearing (CS method) and floating
method (FL method) are 34.2 m and 14.6
m, respectively, indicating that the end
bearing sheet pile is about twice as longas the FL method. In the meantime, theaverage end bearing and floating sheet
pile lengths of the PFS method are 38.7
m and 25.5 m, respectively.
Performance of Steel Sheet Piles
under Earthquake
Fig. 3 shows the probability density distributions of the subsidence of each typeof embankment. The legend in the figures
shows the type of sheet piling method forthe inner side of the embankment. The subsidence of the no countermeasure section
is measured in total of 551 points at thesites and is distributed over a wide rangeof -1.28 m to 1.56 m, whereas the subsidence of the section reinforced by the various steel sheet piling methods is concentrated in the range of -0.08 to 0.39 m.
In order to investigate the effect ofvarious methods and combinations ofTable 1 Statistics of Sheet Pile LengthNo.

Mean (m) Mode (m)COV*

Min (m) Max (m)methods on subsidence control, Table 2
summarizes the statistics of subsidence
caused by earthquakes. When the innerside of the embankment was reinforcedby the PFS method, the average subsidence of the embankment reinforcedby the FL method (outside of the embankment), ground improvement (outside of the embankment), and no countermeasure (outside of the embankment)
was 0.11 m, 0.08 m, and 0.04 m, respectively, which is a small value. When theembankment was reinforced by the FL
method, the mean subsidence was slightly higher than 0.16 m and 0.13 m for either the inner or outer side of the embankment, respectively.
In addition, the subsidence of theembankment reinforced on the outsideof the embankment tended to be larger
than that of the other methods, for example, 0.39 m was observed at the point
where the embankment was reinforcedby the FL method. The average subsidence of the combination of FL reinforcement and ground improvement was 0.08
m and 0.09 m, respectively.
Conclusions
In recent years, there are a large numberof natural disasters such as heavy rains
and earthquakes, and the sheet piles canbe an effective countermeasure such as
the stability of the river embankments.
A construction technique called press-in
method has also accelerated the application of the sheet pile method. Finally, it
is hoped that more wide varieties of thesteel sheet piles should be used.

CS method

35

34.2

37

0.24

14

42

FL method

121

14.6

15

0.41

8

30

End bearing

99

38.7

40.5

0.13

28

53

Floating

99

25.5

25.5

0.22

11.5

36.5

Table 2 Statistics of Seismic Settlement

Ratio**

99

0.66

0.86

0.20

0.27

0.90

Inland side River side

PFS method* The coefficient of variation** The ratio of floating sheet pile and end supporting sheet pileFig. 3 Probability Density Function of Settlements

Probability density function (%)

100

80

Inland
side

60

All
No countermeasure
CS method
PFS method
FL method
Ground improvement

40

0

All

645

No countermeasure

551

0.10

2.36

1.56

-1.28

Countermeasure

64

0.09

1.06

0.39

-0.08

FL method

4

0.15

1.44

0.39

-0.08

GI**

2

0.03

1.41

0.07

0.00

No

8

0.01

5.06

0.13

-0.07

FL method

29

0.11

0.84

0.38

0.00

GI**

3

0.08

1.09

0.15

-0.02

No

17

0.04

0.90

0.14

-0.01

FL method

4

0.08

1.11

0.15

-0.04

GI**

3

0.09

0.73

0.16

0.05

No

8

0.16

0.39

0.26

0.08

No

FL method

15

0.13

1.00

0.39

-0.06

GI**

GI**

1

0.05

-

0.05

0.05

CS
methodPFS
methodFLmethod

20

-0.3

-0.2

-0.1

0

0.1
0.2
Settlement (m)

0.3

0.4

0.5
Over

No. Mean (m) COV * Max (m) Min (m)
0.10

2.24

1.56

-1.28

* The coefficient of variation** Ground improvement
August 2021 Steel Construction Today & Tomorrow 14

Towards the Realization of
Resilience Innovation for 2035
by Haruo Hayashi
National Research Institute for Earth Science and Disaster Resilience
Haruo Hayashi: He finished the doctoral course at
the Psychology Department, University of California,
Los Angeles in 1983. He became Professor, Disaster Prevention Research Institute, Kyoto University
in 1996 and assumed his current position as President, National Research Institute for Earth Scienceand Disaster Resilience in 2015. His specialized
field is social psychology and risk management.

Can Japan Hurdle National
Crisis-level Disasters in the First
Half of the 21st Century?
It is forecast that a series of national crisis-level natural disasters will occur inJapan in the first half of the 21st century. To cope with such a situation, it will
be necessary for Japan to hurdle the fateful crisis triggered by lingering predicaments that will follow these national crisis-level natural disasters. (Refer to Fig.
1)
The major factor attributable to theoccurrence of such national crisis-leveldisasters is two great earthquakes forecast to occur in the near future (refer toFig. 2): One is the Nankai Trough earthquake that has occurred every century since the seventh century and is forecast to occur before and after 2035 (refer
to Fig. 3). The other is the inland earth-Fig. 1 Existential Risk for Japan in the First Half of 21st Century
Extreme weather・Climate change
Kuril Islands
earthquake & tsunamis(Urban disasters)(Consecutive disasters)

Tokyo Metropolitan
earthquake

Series of inland
earthquakes
in western Japan$3T
Nankai Troughearthquake & tsunamis(Landscape scale disaster)
2035

2020

2050

Population decline/Aging society/Dependency on foreign energy and foods

Fig. 2 Expected National Crises

Fig. 3 When Would Be Next Nankai?
Near field Tokyo 2013 scenario

Seismic intensity
7
6+
65+
54
3 or lower

Mw=9.0Max casualties 320,000
Direct loss ¥220 trillion
15 Steel Construction Today & Tomorrow August 2021

Murotsu, Kochi

・Time
prediction
model fits
Seismic intensity
7
6+
65+
54 or lower

Mw=7.3
Casualties 4,930-22,460
Direct loss
¥95 trillion

2035±10(Shimazaki &Nakata, 1980)

Ground elevation (m)Nankai Trough 2012 scenario>JMA6140,000 km2

Severe predicament
due tolong-term recovery

1946
1854

1707
2035

What Is Disaster Resilience?
Disaster resilience can be modelled asshown in Fig. 5. Due to damage causedby disasters, there are cases in which thesystem partially or entirely loses its function. When the lost function of the system may be recovered by starting recovery system after a certain period of time,
there arises a triangle of business disrup-

Earthquake

Magnitude

2012
scenario

2003
scenario

M9.0

M8.7

80,000 –Killed/missing 320,000
257,000 –Injured
623,000
Buildings–
627,000 –collapsed
1,346,000
Buildings–---heavy damage
Buildings–
burned50,000 –750,000

Evacuees
(max)

----

Direct damage(¥ trillion)

220

24,000300,000

Tokyo Near Field

Tohoku
2011

Kobe
1995

2013
scenario

2005
scenario

M7.3

M 7.3

M 9.0

M 7.3

11,00019,2946,434

240,000

6,100

44,000200,000

126,500

105,000

5,000 –
22,50090,000 –120,000

450,000--------------

227,600

144,400

90,00038,000 –412,000

650,000

---

7,400

480,000

320,000

17

10

6,000,000 7,200,000 7,500,000
81Fig. 5 What Is Disaster Resilience
100%

95

112

Business disruption(Vulnerability)

DamageRecovery time
Incident

Adapted fromTime

Fig. 6 An Integrated Approach Is a Key
for Improving Disaster Resilience
100% Business disruption

Improvingpreparedness capability

Damage (Vulnerability)
Improving
prevention/
mitigation
capability

Recovery time

Incident

Time
Adapted from

Fig. 7 Four Operations Prioritized for
Improving Disaster Resilience
100%
FunctionFig. 4 Huge Damage Is Expected
Nankai Trough(Tōkai, Tōnankai,
Nankai)tions. In other words, this triangle canbe explained as the vulnerability that thesystem possesses. How to minimize thistriangle area depends on the improvement of disaster resilience.
To attain the above goal, there are two
independent strategies-improving prevention capabilities to lessen the damage
and preparedness capabilities to speed
the recovery. The best strategy is the
combined use of these two capabilities toimprove the comprehensive capabilitiesof the strategy (refer to Fig. 6). Specifically, the following four operations arecited in order to improve disaster resilience (refer to Fig. 7):

Functionslion yen for the Great East Japan Earthquake of 2011. For the reconstruction
from these earthquakes, a sum of 17 trillion yen was required for the Great Hanshin Earthquake, and a sum of 32 trillion yen has thus far been required for
the Great East Japan Earthquake. The direct damage from the national crisis-level disasters forecast to occur in the future is estimated to surpass 300 trillion
yen in the worst case, and when indirect
damage is also added, the huge amountof 1,250 trillion yen will be required toattain full restoration according to trial
calculations by the Society of Civil Engineers (refer to Fig. 4).
Portugal was once a superpower that
divided the world into two, but the country’s fortunes declined steadily starting with the Lisbon earthquake of 1755
and has shown no notable recovery evenin recent times. In order for the Nankai
Trough earthquakes in the 21st century not to play a triggering role of bringing about the decline of Japan, it will benecessary to establish by 2035 a society
with redundant “resilience” that can hurdle such national crisis-level disasters.

Functions

quake that is feared to occur in the Tokyo
Metropolitan area nearly simultaneouslywith the Nankai Trough earthquake. In
addition, it will be necessary to take into
account the serious damage caused by aseries of inland earthquakes that are forecast to frequently occur centering on thewestern Japan area during that period.
Serious damage brought about by a series of such earthquake disasters will require restoration and reconstruction processes that will span a long time. Further,
it is forecast that such restoration andreconstruction scenarios will be madeworse due to increasing extreme climate
events and ongoing global warming.
The reason why I dare to call thesedisasters national crisis-level disasteris that Japan has certainly experienced
notable political changes after the occurrence of the following four most recent Nankai Trough earthquakes. In the
Keicho earthquake of 1605, politicalpower shifted from the Toyotomi administration to the Tokugawa government,in the Hoei earthquake of 1707 from theTokugawa head family government to
the Kishu Tokugawa family government,in the Ansei earthquakes of 1854 fromthe Tokugawa government to the Meiji government, and in the Showa earthquakes of 1944 and 1946 from the Empire of Japan to Japan of today.
The monetary damage caused by
the largest-scale natural disasters Japan
has experienced in the postwar periodamounted to 10 trillion yen for the Great
Hanshin Earthquake of 1995 and 17 tril-

Stop Vulnerability
operation
ops
D
Maybe
continue
R
ops
High
Must
Regularcontinue pri- recovery
ority
ops
Disasteroperations
ops

Time

Adapted from MCEER model on Lifeline

August 2021 Steel Construction Today & Tomorrow 16

• Firstly, functions that are not complete-

ly lost are identified and the prevention
effort is concentrated on maintaining thebusiness continuity capabilities playedby these functions. Taking the electricity supply as an example-In the Great
East Japan Earthquake of 2011, Fukushima No. 1 nuclear power plant had
lost its function due to tsunamis, which
greatly affected social activities, showing how basic function maintenance isimportant.
• Secondly, continued investment is directed for items conducive to enhancing prevention capabilities. In other words, it isimportant to clearly show those items forwhich function loss occurs in the eventof a disaster. This concept can easily beunderstood in the following example:
While investment in the maintenanceof an electricity transmission network
is preferably continued, the electricity
supply network is identified as an item
whose function may be lost in the eventof a disaster, provided that certain operations should be preferably taken for
its early recovery.
• Thirdly, available restoration resources are concentrated on those items thatshould be given top priority for restoration. In this regard, there are many cases
in which restoration resources are preferentially allocated to schools and hospitals that have a highly public nature, as
well as the industrial infrastructure that
supports employment in the local area.
• Lastly, restoration is to be achieved as
early as possible in a broad way.

How to improve disaster resilience isnone other than how to hurdle disasters
with the main target of minimizing lossof function of the system as a whole bymeans of the comprehensive design of
all operations involved in disaster prevention.
Three Capabilities Composing
Disaster Resilience
In order to improve disaster resilience, it
is imperative to improve prediction capabilities, prevention capabilities and response capabilities in a well-balancedmanner (refer to Fig. 8). The starting
point is to improve prediction capabilities, and this is the issue involved in risk
assessment. We are surrounded by diverse kinds of hazards, but we do nothave the resources to manage all of thesehazards. Accordingly, we are to manage in turns respective serious hazards
in which the product of the hazard probability by the scale of the effect in theevent of a hazard is large.
As regards serious risks, in order tosuppress the occurrence of damage, weare to make efforts to improve prevention capabilities. Hand washing, gargling and mask wearing are effective as acountermeasure against COVID-19, butthese countermeasures cannot be applied
as a prevention measure for earthquake
disasters. As can be seen from this, comprehensive prevention measures that are
effective against any kinds of hazards are
not available. Prevention measures areprepared for each respective hazard, andFig. 8 Three Components of Disaster Resilience
HazardEarthquakes

Structural
Resilience

Tsunamis
Volcanic
eruption
Flooding
Storms
Fire

Major
risks

Construction
Prevention
Mitigation

WelfareEducation
ETC.

Risk
assessment(prediction)

Too muchrisks

Risk specificcountermeasures

Pandemic
Other
risks

Terrorism
Society
Exposure
Vulnerability

Community
resilience

17 Steel Construction Today & Tomorrow August 2021

Preparedness
Response
Recovery

Generic
frameworkof crisis
management

high professional expertise is required to
be provided to manage each hazard. In
this way, prevention capabilities are divided vertically into divisions and thus it
has become difficult to obtain mutual understanding between hazards.
As far as disaster prevention capabilities are concerned, the prevention capabilities of Japan, especially as applied tovarious types of structures, are accepted as world class, but their further improvement will require a vast amount offunding and time. Given this situation, it
seems difficult for prevention capabilities to achieve outstanding improvement
until national crisis-level disasters occur
around 2035.
So, it is the improvement of response
capabilities that offer high expectations
in dealing the above issue. The main
aim of response capabilities is to recover from damage on the condition thatdamages occur in the event of a disaster, and its noteworthy feature lies in that
response means does not change even if
any damage caused by any kind of hazard would occur. The social response to
COVID-19 is basically similar to thatto the damage caused by earthquakes,
strong winds and floods. Therefore, theimprovement of response capabilities forfrequent climate-induced disasters leads
to the improvement of response capabilities for earthquake-induced disasters.
How to Improve Response
Capabilities for Natural Disasters
Response and prevention capabilities
for disasters are improved by hazards.
However, in order to improve response
capabilities, it is necessary to know theconsequences. For the improvement ofresponse capabilities, the inconvenienteffects brought about by disaster are arranged one by one, and then a responsemeans is worked out to dispel each inconvenient effect.
In order to put into effect an effective
disaster response means, due consideration is to be paid to the following fivetasks (refer to Fig. 9):
The first task is the establishment ofcommon operation picture for the situation awareness (refer to Fig.10). Disasters produce a new reality or situation
following rapid environmental changes. It is necessary for those concerned to
rapidly and correctly recognize the newsituation. This is an urgent task in termsof time.
Second is the implementation of disaster response measures. There are threekinds of tasks in which the peak periods
after the occurrence of a disaster differ
from each other. The priority task during
the first period of 100 hours just after theoccurrence of the disaster is to protect
human lives. The second task to be mainly promoted during the subsequent 1,000
hours is to restore the social flow. Normally, society works with the support of
the flow of people, goods, money, and information. It is the disaster that suspends
this normal flow, and therefore the social
flow must be rapidly restored to a normal state within this duration, and at thesame time operations to temporarily support lives until this is restored also enter
into the peak period. After the passing of
1,000 hours, the third task is caried out
mainly targeting the restoration of collapsed towns and the reconstruction of
the daily lives of victims. While the timing in which these three tasks enter into
their peak stages differs from each other,due attention should be paid to the following: in cases when these three tasks
are not implemented in parallel, there
arises fears that the response has been
missed.

Fig. 9 Five Tasks for Effective Disaster Response
Hours passed

1Hr

In order to effectively implement
these four tasks, the fifth task must be
implemented-that of planning the restoration measures and promoting logistics support throughout the disaster restoration period (refer to Fig.11).

Fig. 10 Common Operational Picture Using GIS

10Hrs 102Hrs 103Hrs 104Hrs 105Hrs

Operations

Commonoperational picture
Emergency
response

Common operational picture

Emergency
reliefRecovery/Reconstruction
Planning/
Logistics

Fig. 11 SIP4D (Shared Information Platform for Disaster Management)
Useful information products on-site

COLLECT

SHARE
Information sharing with the on-site disaster response team

INTEGRATE
・Estimation ofproperty damage
・Road info
・Shelter info etc.

Information
Support Teamon-siteInformation “pipeline” to connect between the disaster site and research has maximized the impacts

August 2021 Steel Construction Today & Tomorrow 18

JISF Operations

2020 AJSI Webinar: Energy-Efficient andEnvironmental Transition towards Sustainable
Steel Industry

The Japan Iron and Steel Federation(JISF) concluded a memorandum with
the ASEAN Iron and Steel Council infostering interaction with regard to environment, standardization and trade in
May 2014. Since then, in the field of theenvironment, with the cooperation of
the Ministry of Economy, Trade and Industry, JISF has started up a public-private collaborative platform called theASEAN-Japan Steel Initiative (AJSI),
through which JISF has extended support for energy efficiency and environmental protection in the ASEAN steel
industry.
On December 14, 2020, as a linkof AJSI, JISF held the online seminar“2020 AJSI Webinar: Energy-Efficientand Environmental Transition towards
Sustainable Steel Industry” targeting Indonesia, Singapore, Thailand, the Philippines, Vietnam, Malaysia and Myanmar,
to which a total of around 200 persons
from the government, steelmakers andothers in those nations participated.
For the ASEAN steel industry which
has been impacted by the COVID-19 aswith other nations, the webinar covered
examples of short-term energy efficientand environmental protection measuresthat are currently in high need and simple
in practical use. In addition, the webinar
provided information about medium- tolong-term energy efficient and environ-ment initiatives and trends. In particular, because there are many steelmakers
in ASEAN that operate electric furnaces and are engaged solely in rolling, examples of small-scale technologies andlow-cost operation improvements werepositively taken up, which acquired extremely high assessment from the participants and the South East Asia Iron andSteel Institute as well.
JISF, jointly with the Japanese government, is determined to continue tosupply support for energy efficiency andenvironmental protection to the ASEAN
steel industry through the activities of
AJSI in the future.

Technical Report of Long-term Exposure Tests forConstruction Materials
The Committee on Overseas Market Promotion of JISF has recently published an
English-version technical report titled“Durability Assessment of Various Kindsof Construction Materials by Means ofLong-term Exposure Tests.”
The Research Group on Corrosion
Protection and Durability of Offshore
Steel Structures of JISF, jointly with the
Public Works Research Institute, a publicresearch organ, had conducted long-term
exposure tests for 28 types of construction materials since 1982 at two different
testing sites at Okinotorishima (19 yearsof exposure) and the Marine Engineering Research Facility in Suruga Bay (24years of exposure) to assess the durability of these construction materials.
Okinotorishima is located at thesouthernmost tip of Japan in a tropicalzone where temperatures and humid-

ity are high, and radiation is also high.
Further the tidal current and wave height
are also high and the island is constantly subjected to seawater splashing. Thus,
the corrosion environment at Okinotorishima is far stricter than that in the peripheral sea areas of Japan.
Meanwhile, in order to assess thelong-term durability in the peripheral sea
areas of Japan, the offshore atmosphericexposure tests were conducted employing identical construction materials in
Suruga Bay located on the main islandof Japan in parallel with testing at Okinotorishima.
The report makes a comparison of
exposure test results between these twodifferent corrosion environments andprovides useful data pertaining to the durability of various types of steel and other metallic materials and coated/sprayed/

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 https://www.jisf.or.jp/en/index.html
Japanese Society of Steel Construction
3F Aminosan Kaikan Building, 3-15-8 Nihonbashi, Chuo-ku, Tokyo 103-0027, Japan
Phone: 81-3-3516-2151 Fax: 81-3-3516-2152
URL http://www.jssc.or.jp/english/index.html

19

lined/painted corrosion-resistant structural members to be applied in tropicaland other severe offshore environments.
The full text of the report and its attachments (reference photos) are published on the JISF website:
https://www.jisf.or.jp/en/activity/sc-reports/
index.html© 2021 The Japan Iron and Steel Federation/Japanese Society of Steel Construction
Edited byCommittee on Overseas Market Promotion, The Japan Iron and Steel Federation
Chairman (Editor): Keiji AndoP 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: https://www.jisf.or.jp/en/activity/sctt/index.html. We welcome yourcomments about the publication and ask that you contact us at: sunpou@jisf.or.jp.