No. 56 April 2019

STEEL CONSTRUCTIONTODAY & TOMORROW

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

Special Issue

Japanese Society of
Steel Construction
Feature Articles: Japanese Steel Construction Technologies

1 Renewal Project for Route 1 Haneda Line
3 Ariake Arena

5 Ariake Gymnastics Centre

7 Olympic Aquatics Center

9 New National Stadium in Japan

Special Article: Stainless Steel

11 TOKYO MIDTOWN HIBIYAJSSC Commendations for Outstanding Achievements in 2018

• Outstanding Achievement Awards

13 JR GATE TOWER

14 KYOBASHI EDOGRAND

15 Improved Seismic Resistance of Existing Bridge Columns

PHOTO: CENTRAL JAPAN PHOTO: SS, INC.
RAILWAY COMPANY• Thesis Awards

16 Loading Tests in the Large Deformation Range for RHS Columns
with Different Manufacturing Processes

17 A Trial on Improvement of Fatigue Crack Detection of Eddy Current
Test by Applying C-scope Imaging

18 JSSC International Events
Back cover Message from JSSC International Committee Chairman
Published Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel Construction

Feature Articles: Japanese Steel Construction Technologies
The Pacific Structural Steel Conference (PSSC) is planned
to be held in Tokyo in November 2019. With regard to the
PSSC 2019 in Tokyo, the feature articles in Issue No. 56 highlight five notable steel-structure technology projects ongoingin Tokyo, among which are advanced facilities with distinctive features being prepared for the Olympic and Paralympic
Games Tokyo 2020 in addition to a large-scale renewal proj-

ect being promoted in the expressway network in Tokyo.
On the occasion of the PSSC 2019 and the Tokyo 2020
Games, we are hoping that many readers will visit Japan tomake site visits to these latest facilities and to further seize forthe opportunity to obtain new knowhow and to develop ideas
involved in steel construction.

Feature Articles: Japanese Steel Construction Technologies (1)Renewal Project for Route 1 Haneda Lineby Shigeru Ihara, Metropolitan Expressway Company Limited

BackgroundIn the Route 1 Haneda Line of the Metropolitan Expressway network in Tokyo, the section at the Higashi-Shinagawa pier area and its adjoining
Samezu reclamation area (Fig. 1) commenced service in 1963, and about 55
years have passed since then. The daily average traffic volume of the Haneda Line is about 70,000 vehicles.
The total length of the renewal project currently being promoted in thissection is 1.9 km. Of this total length,
about 1.3 km section at the HigashiShinagawa pier area is located on the
Keihin Canal and close to the sea surface (Photo 1), which thus poses difficulties in carrying out inspections.
On the other hand, about 0.6 km section at the Samezu reclamation area islocated on reclaimed land using steel
sheet pile revetments (Photo 2), where
the highway structure is subjected tosalt damage, and as shown in Photo 3,
significant peeling-off of concrete andcorrosion of reinforcing steel bars havedeveloped.
Given such environments, the project is being promoted as a large-scale
renewal project that aims to ensure
long-term durability and future maintenance management. On-site renewal
work started in February 2016.
Structural Outline of Renewal
Route
The Higashi-Shinagawa pier section

Photo 1 Higashi-Shinagawa pier area

Fig. 1 Section of Renewal Project for
Route 1 Haneda Line
Kohoku JCT

Nishi-ikebukuro

Higashi-Ikebukuro
Iriya

Yotsugi

Photo 2 Samezu reclamation area

Mukojima

Ueno

ShibuyaMeguroHakozaki
Ginza
Daiba

HarumiAriakeKomatsugawa

Shinjuku
Kasumigaseki

TogoshiRenewal section

Haneda Airport
Tokyo Bay

1 Steel Construction Today & Tomorrow April 2019

Photo 3 Peeling-off of concrete and corrosion ofreinforcing steel bars

is reconstructed to a viaduct as shownin Fig. 2. The superstructure is designed as a continuous steel plate girder bridge, and a scaffolding for permanent use is installed on the outer side of
the bridge to secure maintenance performance.
The steel-structure pier is adopted for the bridge pier. Alloy spraying
and heavy-duty coating are applied as
corrosion-protection measures for the
structural section located in the marine
atmospheric zone, and a highly corrosion-resistant stainless steel lining isapplied for the section located in thesplash to underwater zones. The precast/prestressed concrete slab is adopted for the floor slab. For the foundation
structure, the steel pipe sheet pile foundation is adopted that allows for a planar compact design.
In the Samezu reclamation area, inorder to secure the road surface with aheight greater than that of flood tides,
a structural system is adopted in which
the precast box that can secure inspection space on the solidly improved existing ground is connected with each of
the box by the use of prestressed concrete cables.
Fig. 2 Renewal Image of HigashiShinagawa Pier Section

Renewal Steps
In order to avoid the long-term closure of the Route 1 Haneda Line, therenewal process is being promoted stepby step while appropriately controlling
traffic in service, as shown in Fig. 3.
In Step 1, in order to control inbound lane traffic on the Haneda Line,traffic is closed at Oi Junction, and a
detour is constructed. In Step 2, the existing inbound lane of the Haneda Lineis demolished, and a renewal inboundlane is constructed.
In the event of the Tokyo Olympics and Paralympics Games to be heldin 2020, as shown in Step 3 in Fig. 3,
the inbound lane of the Haneda Line isoperated on a detour, and for the out-

bound lane of the Haneda Line, the renewal inbound lane will be operated temporarily as an outbound lane.
In Step 4, the outbound lane temporarily in use for the renewal inboundlane will be switched to the renewal
outbound lane, and the inbound lanethat is temporarily operated as the detour will be switched to the renewal inbound lane. Finally, the detour will be
removed.
Important Test for Future Highway Renewal Projects
Capitalizing on precast members andother rapid construction methods, thedetour was put in service on September
14, 2017, about one and a half years

after the start of the on-site renewal work. Photo 4 shows the conditionin which corrosion-protection measures were applied to the steel bridge
pier by means of highly corrosion-resistant stainless-steel lining. Currently,
the construction of superstructures andbridge piers for the new inbound lane
has reached its peak period (see Photos 5 and 6).
The renewal project for the Route 1
Haneda Line introduced above is thefirst case of its kind in Japan. The project is positioned as an important test
for large-scale highway renewal projects to be promoted in the future. ￭Fig. 3 Renewal Steps
Step 1 Construction of detour

Step 2 Construction of renewal inbound lane
*The current situation of the renewal project

Inboundlane
Inbound Outbound
lane
lane

Outboundlane

Photo 4 Highly corrosion-resistant stainlesssteel lining

Step 3 Construction of renewal outbound lane
(Renewal form at the stage of 2020
Tokyo Olympic and Paralympic Games)

Inboundlane

Outboundlane

Step 4 Removal of detour after
the start of service at renewal lane)
Inbound Outbound
lane
lane

Photo 5 On-site condition (inbound for urban
center of Tokyo)

Photo 6 On-site condition (left: renewal inboundlane under renewal)

April 2019 Steel Construction Today & Tomorrow 2

Feature Articles: Japanese Steel Construction Technologies (2)Ariake Arena-Seismically-isolated Large-space Roof Structureby Yuki Hamada, Takenaka Corporation
Outline of Building Plans
Ariake Arena is planned to be used as
the indoor stadium for two games at the
Olympic and Paralympic Games Tokyo
2020-the stadium for Olympic volleyball and Paralympic wheelchair basketball. It is an arena facility composed of amain arena that can accommodate about
15,000 spectators and a sub-arena thatis located at the south side of the main
arena. After the Olympic and Paralympic Games, plans call for the arena as avenue for not only sports events but also
concerts and so on.
The main arena has a configuration inwhich the exterior wall upwardly opens

outwards and the roof inside the arena is
structured in a downwardly convex form.
Under the restricted site conditions, certain devices are incorporated so that the
air volume inside the main arena is minimized while securing the spectator capacity. Table 1 shows an outline of thearena and Fig. 1 an illustration of the arena’s appearance upon completion.
Construction is steadily ongoing withcompletion targeted around the end of
2019.

Outline of Structural Planning• Directions in Structural Planning

The main structure of the stand sectionis planned as a reinforced-concrete structure with high stiffness from the viewpoint of preventing vibrations due toexcitation caused by a great number ofspectators.
For the core framing structure at four
corners that carries the horizontal forceof the roof section during earthquakes,
a steel-frame structure is adopted andFig. 1 Illustration of Completion of Ariake Arena

Table 1 Building Outline
Location

Ariake, Koto-ku, Tokyo

Building structure

5 stories abovegroundTotal floor area

About 47,000 m2

Height36.7 mBasic design and supervision

Kume Sekkei Co., Ltd.

Design development/detaildesign and construction

Takenaka
Corporation

Technical guidance

Masao Saito(As of October 2015, Tokyo Metropolitan Government)

Fig. 2 Structural Diagram of Main Arena and Sub-arena
Main arena roof

About 120 m

V-shaped brace
Main arena
ings
between bear
LRB
About 110 m
Oil damper
CLB

Stand structure

RB

SSR

SSR bearing
Ribbed wall
RC projecting
columnRibbed wall
RC projecting column
Sub-arena

42 m

Buckling-restrained brace(W)

Roof weight
Roof truss

About 179 m

Core framing structure(N)

About 130 m(E)

About 138 m

Stand section(S)

3 Steel Construction Today & Tomorrow April 2019

planned to have sufficient redundancy interms of both stiffness and strength.
For the roof structure, the steel-frame
plane truss is adopted on the premise oferecting the large-space roof by the traveling construction method. Further, inorder to mitigate the danger of fallingceiling and suspended equipments during great earthquakes, a seismically-isolated roof structure is adopted in which
the isolation devices are arranged justbeneath the roof.
Fig. 2 shows a structural diagram of
overall arena structure.

• Plan for Stand Structure and Core

Framing Structure
For the erection of the stand structure,
it is planned to adopt precast structuralmembers as much as possible from theperspective of enhanced labor-saving.
Further, in the column section that supports the roof, the ribbed wall is arranged
to secure the stiffness itself, and the roof
supporting points are adjusted in order tocause no bending moments at the column
bottom in the long-term loading.
For the core framing structure at thefour corners, buckling-restrained braces are arranged to ensure high stiffness
and strength. The structural members
to be installed in the boundary between
the core framing structure and the standstructure are reinforced to integrate these
two structures.

• Plan for Roof Structure

The roof structure is composed of 22
main trusses and 7 connecting trusses arranged orthogonally to the maintruss. The main trusses are arranged at
6-m spacing, with a truss depth of about

6.4~9 m, and a roof span of approx. 120m.
In the erection of the roof structure,
the traveling method is adopted in which
each truss is assembled one by one on atemporary platform to be installed on the
sub-arena and the trusses thus assembled
are sent out in an orthogonal direction to
the main truss. In order to secure the selfstanding stability of the roof under construction, the roof truss is designed as
one-way truss for dealing with long-termloading, and as two-way truss for dealing with short-term loading due to windand seismic loads. On the top surface ofthe roof, the horizontal brace is arranged
to secure in-plane stiffness. On the bottom surface, the lower chord of connecting truss is arranged to secure in-plane
stiffness. In addition, the steel beam that
also serves as the catwalk bed arranged
orthogonally to the main truss is planned
to have a function as a lateral stiffening
member for the main truss lower chordto which compressive force is partly applied during earthquakes.
In order to improve the sound insulation performance for neighboring areas and to realize various suspending arrangements during events, a structuralfeature is cited-the total weight of theroof structure of the main arena is heavier than that of common large space roof
structures.

• Plan for Seismic-isolation Layer

Because the roof supporting section of
the stand structure has cantilever columns with comparatively small stiffness
orthogonally to the exterior wall, lowfriction sliding supports with rubber-pad(SSR) are arranged so that the horizontal

force occurring in the roof section is nottransmitted to the stand structure during
earthquakes.
In the core framing structure thatcan secure high stiffness in every direction, it is planned that lead rubber bearing (LRB), rubber bearing (RB) and oil
damper (OD) are arranged so that thehorizontal force occurring at the roof
section is intensively transmitted to thecore framing structure. On the top of
the north and south exterior walls, twocross linear bearings (CLB) are arranged
to control vertical deformation duringwind and seismic loading. Fig. 3 showsa structural diagram of the roof structureand seismic-isolation layer.
Outline of Roof Steel Framing Erection and Traveling Construction
In the assembly of the roof steel frames,
it is planned that the truss will be divided
into five portions; the truss members areassembled on the ground, and then hoisted on the temporary platform about 20 m
above ground; and the roof steel frames
are assembled.
For the traveling construction, thecommon practice is to send out steelframe truss by a span. However, in thecurrent traveling plan, it has become
clear from the preliminary structural analysis in accordance with the roof
erection procedure that deformation inan orthogonal direction to the main truss
becomes larger because the depths ofneighboring trusses differ and the roof
finishing load is comparatively large.
Therefore, a large block composed of as
many as five trusses will first be assembled to secure stiffness in the orthogonal
direction to the main truss. Fig. 4 shows
an illustration of the traveling construction method. ￭Fig. 3 Structural Diagram of Roof Framing andSeismic-isolation Layer
LRB : 4 units
RB : 12 units
SSR : 28 units
CLB : 4 units
OD : 16 units

Fig. 4 Illustration of Traveling Construction Method
Traveling rail
Horizontal brace(roof top surface)

Main
truss

Traveling direction
Connecting
truss

OD

Temporaryplatformfor travelingwork

Traveling rail

CLB

LRB

RB

Large temporary platform
SSR

RB

LRB

Traveling rail

Field assembly yard
April 2019 Steel Construction Today & Tomorrow 4

Feature Articles: Japanese Steel Construction Technologies (3)Ariake Gymnastics Centre-Complex Structure Combined with Timber BSS and Cantilever Trussesby Yoshisato Esaka, Nikken Sekkei Ltd. and Takayuki Nishiya, Shimizu Corporation
Ariake Gymnastics Centre
The Ariake Gymnastics Centre is one of the
major facilities being prepared for the Tokyo 2020 Olympic and Paralympic Games.
For the events of the Olympic Games, itwill be used as a stadium for gymnastics,
rhythmic gymnastics and trampolines, andwhile for the Paralympic Games it will be
used for boccia (precision ball sport). Afterthe conclusion of the games, the stadium
will be used as an exhibition hall.
“Extensive application of timber members in facility construction and sustainability,” the two major schemes in facility construction stated in the Tokyo
2020 Candidate File, are positively embodied in the Ariake Gymnastics Centre design. The defining structural feature is the large indoor space, spanningapproximately 90 m, which is realized bymeans of wooden construction employing large-section laminated lumbers.
An outline of the building is shown in
Table 1.

Fig. 1 Bird’s-eye Perspective View of
Ariake Gymnastics Centre*

Table 1 Building Outline
Planned location
Building area; Total floor area
Fire-proof building
HeightNo. of stories
Structure

Ariake 1, Koto-ku, Tokyo
About 21,200 m2; About 39,300 m2
Root C (ministerial approval)
About 30 m
3 stories above ground
Roof: Timber structure, partly steel structure
Lower part: Steel structure (moment frame
structure with braces)
Foundation: Pile foundation (precast pile)

Structural calculation route
Basic design, design development/detail design
supervision, construction supervision
Design development/detail design and construction
Technical guidanceRoute 3
Nikken Sekkei Ltd.

Architectural Design and
Structural System• Architectural Design
The current building has two major architectural features: firstly, an extremely flatarch configuration and lightweight, sharp
appearance which is brought about bymeans of the deeply protruding eaves (Fig.
1); and secondly, a dome space structuredby the use of wooden members (Fig. 2).
Fig. 2 Inner View Perspective View of
Ariake Gymnastics Centre*(*Courtesy of The Tokyo Organizing Committee of the Olympic and Paralympic Games, Completion
image as of November 2017)

Fig. 3 Structural Outline

Timber
(2-220×1150)

1150

1150

Strut (P-141.3×32)
Plywood
9.6 m

Timber
(2-220×1150+1-220×930)

69.6 m

660

9.6 m

660
5.2 m
2.5 m

Sub-strings(1-φ28.6)
Main cable (2-φ56)
88.8 m
5 Steel Construction Today & Tomorrow April 2019

Sub-strings(2-φ21.8)@7.2 m

Shimizu Corporation
Masao Saitoh• Structural System

In order to harmonize this architecturaldesign with structural mechanics and toensure construction rationality, we proposed the structural system that is comprised of a Complex Structure combined with Cantilever Trusses and Beam
Strings Structure (BSS).
A large space with a span of approximately 90 m is provided by the combined
use of the cantilever trusses (9.6 m) arranged at both ends (composed of steel
frames and laminated lumber) and the BSS(69.6 m, @7.2 m) arranged in the center
section (composed of laminated lumber, cables and struts). This is illustrated in Fig. 3.
BSS is a self-balanced structure that iscomprised of three main elements: by theupper chord timber beam which acts as aflexural and compression member, the steel
cable (string) which acts as a tension member, and finally the axial compressive struts
to connect them. In order to make use of theself-balanced feature of BSS, a lift-up erection method is proposed (Fig. 4). As a result, a structural system is realized in which
the thrusting force resulting from the deadweight of the roof does not occur and inwhich the arch structural resistance to theload of BSS is demonstrated after the erection. Further, taking into account the occurrence of diverse kinds of loads, sub-cables(sub-strings) are proposed so that the stiffness and strength of the roof are improved.
In the long-side direction of the roof, identical framings composed of 15 planes ofstructures are continuously arranged, andfurther structural plywood having a thickness of 28 mm is arranged horizontally on
the entire surface of the roof.

Fig. 4 Lifting-up BSS

Fig. 5 Position of Respective Joints

Beforelifting-up

Timber’s joint (GIR)After
lifting-up

Outline of Roof Structural Design• Design Loads and Design
OutlineTwo erection procedures (tension introduction and lifting-up) were consideredwhen examining the sustained load.
Two main variations of snow loading
are considered for the roof―a uniform
snow load of 750 N/mm2, determined bytaking into account an increment coefficient α=1.21 (in consideration of rainfall
after snowfall), and unbalanced loading(one-side eccentric and center eccentric)
that is unfavorable for the arch structure.
The wind load is calculated basedon wind tunnel test results, as well as
code-based calculations in compliancewith the Building Standard Law of Japan and the Architectural Institute of Japan’s (AIJ) Recommendations for Loads
on Buildings (2015). Additionally, it has
been confirmed that the tension forces in
the main cables do not disappear when
there is uplift of the roof due to windloading.
For the roof seismic loading, a combination of static loads, a lateral seismic coefficient of 1.35G and a vertical seismic
coefficient of ±1G, are adopted. Further,
the stress in the structural members occurring in the anti-symmetric-mode duringhorizontal seismic motion is confirmed
using time-history response analysis.

• Detail of Joints

Fig. 5 shows the position of respective
joints. Because BSS system spans approximately 70 m, it is composed of curved
beams divided into 5 separate sections.

Fig. 6 Joints for Lifting-up

Joint for lifting-up

Therefore, it is necessary to provide 4
joints. In connecting the timber members
at the end of each section, GIR (glued-inrods) joints using adhesives and steel reinforcing bars are adopted. These benefit
from high strength and stiffness, and areconcealed so that they do not hinder thearchitectural design.
For the joining of the cantilever trusses and BSS, the high-strength bolt friction joining method is adopted (Fig. 6
and Photo 1). The end of the cantilevertruss sections experiences vertical deformations by about 40 mm and horizontal
deformation by about 20 mm during lifting. As such, a slotted hole design is adopted (torque-shear type S14T and M24
bolts, minor axis 30 mm, major axis 60
mm, aluminum-sprayed friction surface, acquisition of ministerial approval). A wooden cover is then attached tothe joint section, to which some final finishing is applied so that the timber archappears continuous.
In the cable joining section, the sliding force is usually transferred by meansof the friction that occurs due to the bolt
fastening force of the steel clamp. However, the large sliding force requires acorrespondingly larger steel clamp. To
overcome this, a transfer mechanism bymeans of bearing pressure is proposed
and adopted in the roof erection (Photos 2 and 3). The adoption of the approach mentioned above allows for the
reduction of the steel clamp size to about
half compared to the case of transfer bymeans of friction. To that end, it becomes
possible to adopt a smaller-size lower
steel clamp that is not very eye-catching.

Photo 1 Joints for lifting-up

Joint of the cable• Erection and Roof Lifting-up

The stress and shape (span) of the roof
are controlled by the use of cable tension
force on the erection platform installedon the ground.
In the lift-up plan, three planes ofstructures are set as a unit (69.6 m inlength, 14.4 m in width and about 2,000
kN in weight), which is lifted up toward
the cantilever trusses installed at a heightof 19 m and at a lifting speed of about
5 m/hour (Photo 4). A total of five lifting operations are carried out at a paceof one operation every two months. ￭Photo 2 Model of steel clamp

Photo 3 Steel clamp

Photo 4 2nd lifting-up
April 2019 Steel Construction Today & Tomorrow 6

Feature Articles: Japanese Steel Construction Technologies (4)Olympic Aquatics Center-Structural Features and Constructionby Yasuhiko Asaoka and Kazuaki Abe, Obayashi Corporation; Tatsuya Kataoka, Yamashita Sekkei Inc.;and Ikuhide Shibata, Ove Arup and Partners Japan Ltd.
Outline of the Project
Olympic Aquatics Center is swimmingcompetition venue for Tokyo Olympic
and Paralympic Games 2020. The footprint is approximately 200 m in southnorth (longitudinal) direction and 130
m in east-west (transverse) direction.
The building is 34 m high, and 4 stories
above ground and 1 story underground,consisting of main arena and sub-arena.
The main arena has main pool of 50 mlong and diving pool of 5 m deep, and the
sub-arena has another pool of 50 m for
preparation at the time of Olympic andParalympic Games.
The structural feature is represented
by the roof covering the main arena, thesub-arena roof and the perimeter columns
around the main arena. These elements
are characterized both in structure andconstruction way and the following chapters explain each element. (Figs. 1, 2)
Design Approach
The perimeter column supporting grandstand is slender steel column covered
with prestressed concrete to prevent frombuckling and satisfy with fire and rust resistance, inspiring traditional Japanesestyle. The column is precast at fabricator and is erected at site as if it were steel

column. This can be possible because at
the end of column, the steel column is
exposed while the other part is covered
with concrete, and only steel is connected by welding at site without the rebar of
concrete being free from joint. The upper part of perimeter column is designed
as prestressed composite column, aiming not to cause crack. Once crack happens, the restriction of steel buckling byconcrete becomes slack and the buckling
resistance goes down. And any crack reduces durability and aesthetic sense as
well. (Fig. 2)
The sub-arena roof is total of 43.2 m
span beam consisting of the prestressed
precast concrete beam of 36 m long andsteel truss of 7.2 m long, adding aesthetic sense to the sub-arena. The concrete
beam gives enough stiffness to the roof
as entrance approach. The beam is designed to be in compression against deadand imposed load. This means cracks are
not likely to happen, giving durability inwet condition. The concrete beam dived
into units are precast at fabricator, assembled at construction site and tied byprestressed cables. (Fig. 2)
The main arena is covered with thesteel truss roof spanning 130 m in longitudinal and 80 m in transverse direction,

Fig. 1 Outside View from South-West

Lift-up Construction and
Structural Design
The main arena roof truss is erected atlower level for easy, safe and quick construction, and lifted up from four corner cores to the designed level. Eachcorner core has eight oil jacks with thecenter of them coinciding with the center of rubber bearing. The structural design requires that two rubber bearings
take equal loading from the roof. In order to make this happen, these jacks arecontrolled so that they carry same load,
resulting in the roof deforming as if it is
supported equally by two rubber bearings at each corner core. And the two
rubber bearings can take the same load
if the roof is rest on the rubber bearing
with keeping its deformation when it ishung from these jacks, otherwise inside

Fig. 3 Roof Plan
Perimeter column

Main arena roof

giving column-free space to main arena.
The roof soffit is concaved by 1.5 m at
center, giving comfortable atmosphere.
The roof truss is supported by rubber
bearings at each corner cores. The bearing rubber works as isolator to swap seismic input and to separate the behavior of
the roof from that of the superstructure,
and also as buffer to absorb thermal extension and shrink. (Figs. 2, 3)

Corner core

Eight lift-up jacks for each core

Sub-arena roof

Fig. 2 Section in South-North Direction
Concrete covered steel column

Prestressed concrete beam
Sub-arena

7 Steel Construction Today & Tomorrow April 2019

Steel truss
Main arena

Two rubber bearings for each core

rubber takes most of the load, resulting
in onerous tension at outside rubber due
to wind. (Fig. 3)
The interface between roof and corner core is also designed so that the roof
can rest on the bearing rubber with keeping its deformation shape. The interface
between the roof and the bearing rubber is spherical bearing to fit the rotation of the truss, and the bearing rubber
rests on concrete stub base poured in situ, so that its level can be easily adjusted
to the truss deformation. The anchor bolt
is slotted into concrete filled tube incorporating into support beam from cornercore. (Fig. 6)
Outline of the Roof Steel WorkThe roof truss assembling at construction
site begins with the main truss in longitudinal direction at first. And sub-truss between the main trusses comes next andcantilever in east-west direction follows
it. The main truss in transverse direction
and the cantilever from it are erected atlast. The temporal supports are removed
except under the main truss before liftup.
The main truss in south-north direction is cambered by about 500 mm at
middle so that it becomes flat after lifted
up. On the other hand, the main truss ineast-west direction and the sub-truss areflat in order to avoid making steel fabrication complicate. However, the cantilever truss in south side is cambered tomake flat edge as front façade.

Outline of Lift-up
Lift-up is carried out by the following
three steps before lifting down to thebearing rubber. The deformation of theroof is monitored throughout every stepwith monitoring system developed forthis project. (Photos 1, 2)
At Lift-up 1, the roof floats off from
temporary support by 1.7 m. Most ofroof deflection takes place at this stage
and finish work hereafter becomes freefrom excessive deflection. And this roof
level allows access to ceiling work byhigh deck vehicle.
At Lift-up 2, the roof is pulled up by
another 5 m so that central main monitor
can be hung from the roof.
At Lift-up 3, the roof reaches at the
500 mm above designed level. At thisstage, the roof support cantilever beams
under the bottom chord of the main truss
are welded to the corner core column.

The bearing rubbers are set on the cantilever beam so that its position fits to theroof deformation, which makes the rubber bearings take equal loadings.
At the last step, the roof lifts down
and all the tension force in the strand cable transfers to the compression force inthe rubber bearing. (Figs. 4, 5, 6)

Fig. 4 Lift-up Step

Fig. 5 Lift-up Equipment

Conclusions
These elements feature Olympic Aquatics Center as Olympic and Paralympic venue and offer appropriate qualityof space for the event with proper technics. ￭Oil jack

Lift-up 1

StrandcablesLift-down

Temporary support

Lift-up 2
MonitorLift-up 3 andlift-downCornercore

Removalpart
after
lift-up
Lift-up 3

Main
truss
upper
chord

Lift-up 2
Lift-up 1
Main truss

Transverse direction

Temporary
supportLongitudinal direction

Fig. 6 Interface of Main Roof Truss and Rubber Bearing

Photo 1 Overall view before lift-up

Main truss bottom chord
Concrete stub to adjust
level of bottom chord

Bracket beam from cornercore to support bearing
rubberSpherical cast iron bearing
to adjust inclination of bottom chord

Concrete filled tube to holdanchor bolt with tolerance

Photo 2 Monitoring system view

April 2019 Steel Construction Today & Tomorrow 8

Feature Articles: Japanese Steel Construction Technologies (5)New National Stadium in Japan

by Osamu Hosozawa, Taro Mizutani and Shinichiro Kawamoto, Taisei Corporation
The New National Stadium is a facility that is also used as the venue for the
Tokyo Olympic Games and Paralympic
Games in 2020. This stadium is hoped
to become a place where all athletes canshow their best performance, and to be
loved and used frequently by people offuture generations. Based on the concept
of “Stadium in Forest,” the new stadium
is open to everyone. Becoming a part of
the forest of Meiji Jingu Shrine, it will
form a green network spreading from theInner Garden of Meiji Jingu Shrine to theImperial Palace, and become a “new center of sports cluster” where everyone canenjoy taking walks and various types ofsports. (Refer to Fig. 1)

Building and Structural Outlines
The maximum building height is 50 m
or less, and the low slope roof consistsof a cantilever truss structure of about
60 m in length (Fig. 2). The sense of
oppression to the neighborhood is reduced through building setback fromthe street, with the inclined outer columns. The main structure of the stadium is a steel structure above ground. A
steel-reinforced concrete structure using
precast and prefabricated products is adopted for the oblique beams (i.e. the raker beam), which supports spectator seats,
and for the outer columns, which support
the roof truss. Furthermore, the responsecontrolled structure by Soft-First-Story

Fig. 1 Image of Aerial View from Southeast

The renderings are intended to show conceptual image at completion and may subject to change.
Vegetation shows an image about 10 years after completion of the stadium.
Copyright © Taisei Corporation, Azusa Sekkei Co., Ltd. and Kengo Kuma and Associates Joint Venture

Fig. 2 Outline of Cross Section

system provides a high seismic performance to this stadium.
The hybrid structure composed of thewood and steel materials for the lower chords (Japanese larch) and the lattice members (Japanese cedar), arrangedin the three dimensions of roof trusses,
creates a space where Japanese features
can be felt sufficiently. The wood is usedas the member that controls the deflection of trusses caused by earthquakes andstrong winds.
Simple Stand Structure in Consideration of High Constructability
By employing the same frame composition repeatedly in the circumferential
direction for both roof and stand frame
systems, productivity, transportability,
efficiency of drawings production, andconstructability are improved, which results in the thorough reduction of construction period and cost (Photo 1).
Further, considering the manpower
shortage at current construction sites andthe efficiency of construction site workby unitization, promotion of factory prefabrication is planned. In particular, theunitization of the roof trusses, the precastization of the foundation and the outer SRC column, and the proactive use of
prefabrication products are planned.

Length of cantilever: About 60 m

Minimize the height ofthe building

Middle of ring truss
Point of ring truss
Repeat the same frame

Setback fromthe street

Hybrid structure usingwood and steel

SRC column

Oblique beam to support
spectator’s seat(i.e. Raker Beam)

50 m or less
Steel
brace
Steel structure
OildamperFoundation
9 Steel Construction Today & Tomorrow April 2019

Response controlled
structure
by Soft-First-StorysystemRoad level

Cantilever Roof Frame That Can
Be Built Efficiently
The roof truss is unitized to achieve efficient construction, and reduce the construction period. By creating a one-frame
free-standing structure of cantilevering
truss, simultaneous construction of thestand, the field, and the roof portion canbe achieved (Fig. 3).
The roof frame adopts a frame systemthat has cantilever space trusses with triangular cross sections continuously arranged in the circumference direction.
Two upper chords and one lower chord
are connected using lattice members inthree dimensions. Lattice members contribute to avoid buckling of the upper
chords and the lower chord and behave
as horizontal braces in the roof surface.
The roof is united by joining the webof the upper chords of each unit by theuse of high-tension bolts. Upper chordadopts channel steel (Photo 2).
Response Controlled Structure

Response Controlled Structure
by “Soft-First-Story” System withHigh Seismic Performance
In consideration of the unspecified number of people using the stadium, we decided to give higher seismic performance
than that of general buildings.
Generally, the oblique beams of thestand (i.e. the raker beam) that support
spectators’ seats, behave as brace members, achieving a high seismic resistance.
However, its high stiffness leads to ashort natural period. Therefore, whentime history response analysis is carriedout to confirm the structural integrity, theresults of response are generally so largethat it isn’t possible to design the building within its structural criteria. To deal
with this, it is necessary to add responsecontrol devices that absorb earthquake
energy, or to make the natural period of
the building longer.
However, even if additional damp-

ing is added to a building with high stiffness, like a stadium, this measure doesn’t
have an effect so large as to reduce theresponse of a building. Then, the natural period of the building should be prolonged.
At this stadium, the natural period of
the lower part frame is prolonged as in abase isolation structure (soft story), andthe response-control devices (oil dampers) are arranged there concentrically. This creates the response controlled
structure by the Soft-First-Story systemwith high seismic performance. A less
stiff story compared to the other layers isachieved by adopting a moment resisting
frame of three stories, from the second
floor in the basement, to the first floor
above ground. By providing a soft story
to the three stories, the stadium achieves
high redundancy (Fig. 4). ￭East

Fig. 3 Image of Roof Construction
Unit frame
Start of construction

Crane
Set toroof

Roof frame

End of construction

TemporarycolumnStand frame

Lift upWest
Photo 1 Simple structure plan
Copyright © Japan Sport Council, “Regular Briefing for the New National
Stadium,” Made by 29th handout (October 12, 2018)

Fig. 4 Response Controlled Structure by “Soft-First-Story”
SystemConnection of bolt

Upper chord

Raker Beam

▼5F
▼4F
▼3F
▼2F

Lattice member

Brace

Exp.J

▼1F
Space trusses withtriangularcross sections
Lower chord

Photo 2 Roof truss section
Copyright © Japan Sport Council, “Regular Briefing for the New National
Stadium,” Made by 17th handout (July 28, 2017)

B2F〜1F:Oil dampers are arranged
to absorb seismic energy.

▼B1F
▼B2F

2F〜4F:
Adequate stiffness isprovided to the stories byraker beams and brace.

Oil damper
Foundation level lower
than base isolation building

Frame of 1st tier stand frame

Soft-story is achieved by isolating frame of 1st tier standfrom other members
April 2019 Steel Construction Today & Tomorrow 10

Special Article: Stainless SteelTOKYO MIDTOWN HIBIYA-Application of Stainless Steel in Façade Designby Akira Kubota, Kajima Corporation
Outline of TOKYO MIDTOWN HIBIYATOKYO MIDTOWN HIBIYA wasplanned as an urban redevelopment project covering the reconstruction of two
noted buildings, Hibiya Mitsui Building
and Sanshin Building, and the lot substitution with a street operated by Chiyoda City and sandwiched between thesites for these two buildings. The redevelopment area was designated as a National Strategic Special Zone, the first of
its kind in the Tokyo metropolitan area,
and the project involved the provisionof industry support facilities extending
to 2,000 m2 in area and a business continuity plan (BCP) function including
the support of those who will have difficulties in returning home for 72 hours
in the event of a natural disaster. To that
end, TOKYO MIDTOWN HIBIYA wasplanned as a new symbolic tower in the
Hibiya area of downtown Tokyo.
TOKYO MIDTOWN HIBIYA is ahigh-rise building with 35 stories aboveground and four basements, and a heightof 192 m. In the low-rise section, commercial facilities and a cinema complex
are arranged, in the medium-rise section
there are industry/office support facilities, and in the high-rise section there are
office floors. In the aboveground structure, oil dampers and buckling-restraint
braces are arranged as a response-control
device to reduce seismic response. HiDAX-R developed by Kajima Corp. was
firstly adopted for oil dampers. It demonstrates world-class response-control efficiency and ensures the high safety andbusiness continuity performance of thebuilding.
TOKYO MIDTOWN HIBIYA was
opened to the public in March 2018.
Façade Design of TOKYO MIDTOWN HIBIYA
Under the concept of a “dancing tower,” Hopkins Architects, a leading UK
architectural practice, undertook thedesign of the building exterior as themaster architect. The high-rise tower exterior with an image of elegantly
dancing dresses of dancers is composedof champagne-golden aluminum cur11 Steel Construction Today & Tomorrow April 2019

tain walls prepared by combining vertical fins with delicate details and a pleated configuration. The exterior line thatdraws a gentle arc has four lapped sections, and an impressive appearance isproduced that gives off a florid, complex twinkling.
A dignified design employing a lot ofstately stone members was adopted forthe low-rise section-a design closely resembling the old Sanshin Building,which emphasizes an image of construction integrated with the neighboring
Nissei Theater. The low-rise section is
structured by combining 100 mm-thickpure granite finished only by means ofchiseling with metallic materials prepared with thin details, which produces
a design that gives a stately but sharp,
elegant image-a typical design stylefor Hopkins Architects.
Design Details of the Façade at
Low-rise Section and StainlessSteel Application
Various kinds of decorative items employing stainless steel used for the design of the façade at the low-rise section
were subjected to minute technical ex-

Photo 1 Looking up from the low-rise section

aminations in line with the designer’s
intention, particularly for the application of diverse processing technologies
available for the stainless steel-bending, laser processing of plates and lostwax casting method. The decorative
items thus prepared by applying diverse
processing technologies were rationally worked up, thereby acquiring high assessments from related fields. Not only
commonly-applied SUS304 but SUS405
were applied to realize a structural system of the right materials for the rightplaces.
The upper and lower sections, themain structure of openings in the façade,were structured using stainless steel panels that were prepared by means of bending based on fine details, in which granite frames with natural and simple feelingare arranged using a modern, sharp line
(Photo 1).
The lighting equipment for illumination was assembled into the lower section via stainless steel pedestals to gorgeously direct a sunset expression richin shadow. In the panel at the eaves soffit, a bead blasting processing was applied to the stainless steel surface in or-

1465
268

2618

1465

5800

4888

1465

225

der to restrict the illumination reflection. Fig. 1 Decorative Mullions on
In this way, the building quality is furSecond Floor
ther enhanced by the optimum use of thehigh finishing workability offered by thestainless steel.
3rd fl.
In the second-floor corridor, the decorative mullion and glass canopy, prepared by processing stainless steel pipes
and plates, were incorporated into the façade design as important accents in terms
of aesthetics (Photo 2).
In order to attach importance to therelationship with the neighboring Nissei Theater, a horizontal glass canopy
Rod
SUS Φ76.3×2.0t (HL)that gives a continued aesthetical expresMullion
SUS 12t (HL)sion was provided, producing a town deRod support
sign that enhances an integrated image as
SUS (lost wax casting)a street. The stainless steel pipe mullion
Edge coverSUS FB-3×20 (HL)
was attached to a strut manufactured bylaser-cutting 10 mm-thick stainless steel
SUS 2.0t (HL)
2nd fl.
plates by the use of joining metal fittings prepared using the lost wax casting
method. To these ends, the corridor was
finished to a fine, sharp configurational
structure. (Refer to Fig. 1)
The joint section prepared by the use fice entrance employing stainless steelof the lost wax casting method was fin- is emphasized in the total building deished by means of bead blasting. The sign. (See Photo 3)
The hair line-finished stainless steel
joint thus prepared offers an elegant
configuration with a tender expression, sheet applied in the panel was processedwhich makes a marked
contrast with the sharp
stainless steel pipe andplate members. Thatis, the mullion andglass canopy serve as
an important element
in directing an impressive façade. In thisway, the designer’s intention has successfully and faithfully beenrealized by the maximum use of the flexible and diverse proPhoto 2 Decorative mullions on the second floor
cessing and finishingmethods that stainlesssteel can offer.
A stainless steel
panel was also used
for the gate of the office entrance section.
In contrast to the tower section having a
sharp design, the façade at the low-rise
section has an entirely elegant and stately design, and in thisfaçade the gate is dePhoto 3 Office entrance gate
signed so that the of-to a detailed configuration having an extremely sharp edge, which allows for the
direction worthy of the office sectionthe direction that draws a clear line between the office and low-rise commercial sections. Further, a combination oflighting equipment high in color temperature and hair line-finished stainless steel
sheeting finishes a gate that offers cool
beauty.
It can be said that the high quality andflexibility offered by stainless steel has
played a role in imparting enhanced gorgeousness and beauty and a high-grade
appearance to the entire building structure capitalizing on Hopkins Architects’design.
Good Start as a New Cultural Base
After the grand opening of TOKYO
MIDTOWN HIBIYA in March 2018, it
has gained a high assessment and many people have visited there. It has madea good start as a base to creating a new
culture. All the parties concerned arepleased with this and also hope that theTOKYO MIDTOWN HIBIYA area willattain further development in harmony
with its surrounding environment. ￭April 2019 Steel Construction Today & Tomorrow 12

JSSC Commendations for Outstanding Achievements in 2018-Outstanding

JR GATE TOWER

Prize winners: Toshiharu Ninomiya, Yoshinori Somiya, Junji Toyama and Machiko Sugimura, andJoint Venture of Taisei Corporation and Kajima Corporation
JR GATE TOWER is a complex facility
building that is connected directly withJapan Railway (JR) Nagoya Station. It
is a high-rise building with 46 stories
aboveground (220 m in height) and six
basements (35 m in depth). (See Photo 1)
Location Conditions for Planned Site
The planned site is located in an area sandwiched between two existing railway linesthat run on the east and west sides of thesite. In the first to third basements, the Nagoya Railroad (MEITETSU) railway line
crosses the site, and in the fifth to sixth
basements, there is space of part of the station for the future Chuo Shinkansen SCMAGLEV (bullet train line) at the site.
Due to these location conditions, it has
been required to provide an undergroundstructure having a depth of 35 m in which
there is a box structure for the MEITETSU
railway line. (Refer to Figs. 1 and 2)
In order to cope with these strict location conditions, advance measures havebeen adopted-appropriate column gridplan, transfer truss plan and rectangularconcrete-filled steel tube (CFT) columns.
Rectangular High-strength CFT
Permanent Structural Columns
Because of the adoption of an inverted
construction method, the steel frame thatis built-in in the underground steel-reinforced concrete column was designed as apermanent structural column. In terms ofthe construction process, the axial force ofthe column to be installed just beneath thehigh-rise section reaches as high as 90,000kN at its maximum in the sixth basement(75% that at the stage of completion).
In cases when a steel-frame column is
to be adopted for the column just beneaththe high-rise section, its maximum plate
thickness reaches about 90 mm, which
poses some concerns-strict conditions
for lifting the permanent structural column with lengths of 40 m or more anda significant increase of on-site welding.
Then, CFT column was adopted for thepermanent structural column, which led
to a reduction in plate thickness to 40 mm.
Regarding the range of CFT column insertion into the pile, in order to secure thefilling property of the pile concrete, it was
required to adopt a cross H configurationor an open section for the pile. Then, thefollowing two measures were adopted: In
the range of the upper pile head section (①in Fig. 3), the section of the steel-frame
column was converted from a square configuration to a cross H configuration andfurther structural design was made so thatthe axial force borne by filling concrete
was transferred to the steel frame by theuse of stud bolts. In the range of the pile insertion section (② in Fig. 3), structural design was made so that the axial force wastransferred from the steel frame to the pileby the use of stud bolts and bearing pressure of the pile head. (Refer to Fig. 3)

Fig. 1 Location Environment for
Planned Site

Fig. 2 Floor Beam Framing Plan at 2nd
Basement③ Restriction on grid

JR GATE TOWER

JR CENTRALTOWERSJR NagoyaStationSubwayHigashiyamaLine

due to future plan

① Crossing by
MEITETSU line’s
box structure

Roadway of
JR CENTRALTOWERSMEITETSULine

PHOTO: CENTRAL JAPAN RAILWAY COMPANY

Efforts to Meet Diverse Requirements
In the construction of the JR GATE TOWER, in order to satisfy diverse conditions
arising from the plan, location and construction period, conferences between designers and construction companies were
held from the design stage, and various
kinds of tests that simulate the construction conditions were carried out. ￭Chuo Shinkansen
SCMAGLEV (planned)② Passage of corner section by
MEITETSU line’s box structure

Fig. 3 Stress Transfer Mechanism of Rectangular
High-strength CFT Permanent Structural Column
Axial force borneby filling concrete

CFT permanent structural column

6th basement(Upper end of mat slab)
Range ①

CFT
CFT

Steel
frame
Steel frame

Axial force borne by permanent
structural column
Range ②
Axial force transfer
by the use of stud
Axial force transfer by the use ofbearing pressure of pile end
Photo 1 Appearance of JR GATE TOWER
13 Steel Construction Today & Tomorrow April 2019

Pile reaction force

Steel
frame
Pile
Squaretype

Rectangular
type

Section of permanent structural column

Achievement Awards

KYOBASHI EDOGRAND

Prize winners: Yuji Yamano, Kazuhiko Yoshida, Takashi Fukushima and Satoshi Yagi
KYOBASHI EDOGRAND is an urban redevelopment project promoted in the downtown of Tokyo. On the theme of securing a
new pedestrian moving line due to the disuse of existing local roads caused by the enlargement of streets, a semi-outdoor open
space including a galleria has been provided
just beneath a high-rise office building. The
final goal is to structure a dynamic space inthis redeveloped area. (See Photo 1)
The structural feature lies in the adoption of an intermediate base-isolation layer
in which the base-isolation layer is arranged
between the galleria and the high-rise office area (Fig. 1), due to which seismic motions are reduced, and structural membersother than base-isolation members can be
kept in an elastic state even during large
PHOTO: SS, INC.

earthquakes. To that end, an open, dynamic
space has been realized by making clear theflow of force in the galleria surrounded by a
low-rise section composed of three blocks.
Development of New Base-isolation
Members Employing High-strength
Steel Products
The building constructed in the current redevelopment project is a high-rise building
with a height of 170 m, which is thus subjected to large wind loads. In cases where common measures are adopted, the number ofdampers to be used surpasses the optimum
amount to be required during earthquakes,
which causes a deterioration of the seismic
response performance of the building.
To cope with such situations, an elastic locking mechanism that adopts highstrength HSA700 steel products for flexural beams has been developed and appliedin this high-rise building. The applicationof the new high-strength base-isolation
steel members not only solved the task per-taining to wind resistance but also realizeda base-isolation structure with an optimum
use of dampers.
Elastic Locking Mechanism
A mechanical joining using shear pins was
adopted as the device that joins the upperand lower floors of the base-isolation layer(See Photo 2). During earthquakes that frequently occur, seismic energy is absorbedby the oil dampers in order to ensure theoperation of the elevators.
In the event of large earthquakes suchas the Minami-Kanto Earthquake or Nankai Trough Earthquake that are forecast to
occur in the future, shear pins will cause
fractures, and not only dampers but alsoelastic sliding bearings will jointly absorb
the seismic force. In this way, a systemthat can absorb greater seismic energy wasput into practical application in the KYOBASHI EDOGRAND with the development of an elastic locking mechanism.
(Refer to Fig. 3). ￭Fig. 2 Seismic Design Criteria and Conditions of Respective Seismic-isolation Members
External force level

During medium earthquakeand strong wind
Securement of applicability

Seismic resistancePhoto 1 Full view of KYOBASHI EDOGRAND

During large
earthquake
Securement of safety

Small-amplitude seismic isolation Effect of base isolation(effect of controlling response
attained by optimum use ofconcentrated on specified layer) damper

Displacement at
base-isolation layerδδFig. 1 Structure of KYOBASHIEDOGRAND
Elastic
lockingHigh-rise floor:
Steel structure(CFT column)

Base-isolation floor
Low-rise floor:
Steel-reinforced
concrete structurewith seismic resistantwall; Partly steel
structure

Condition of
Oil damper
base-isolation Elastic sliding
memberbearing
Elastic locking
mechanism7.2 cmAbsorption of seismic energy

50 cm
Absorption of seismic energy

No sliding

Sliding and absorptionof seismic energy
Unlocking of locking

Locking; Returning to original
position after earthquake

Fig. 3 Elastic Locking Mechanism
During occurrence of medium earthquake
Elastic flexural beam moves by about 7.2 cm
with shear pin as fulcrum=Oil damper installedon base-isolation layer absorbs seismic energy
Plan

Force parallel
to earth side

Section A

Force straightto earth side

7.2 cmPhoto 2 Full view of elastic locking mechanism

Unlocking

Earth
side

Earth
side

7.2 cmElastic flexural
beam (upper)
Shear pin

Elastic flexural
beam (lower)
Withstanding

A (Elastic bending) without fracture

During occurrence of large earthquake
In the case when a large earthquake with a magnitude
higher than that of the East Japan Great Earthquakeof 2011, locking is unlocked due to the fracture ofshear pin. Not only dampers but also sliding bearings
jointly absorb large seismic energy.
PlanSection A

A

Unlocking oflocking

April 2019 Steel Construction Today & Tomorrow 14

-Outstanding Achievement Awards

Improved Seismic Resistance ofExisting Bridge Columns-Application of Bridge Columns Integrated by Multiple
Steel PipesPrize winner: Hanshin Expressway Company Limited
With the aim of further enhancing the convenience of highway networks in Osaka,
a project was promoted to reconstruct the
Nishisenba Junction of the Hanshin Expressway. Its aim is the construction of additional lanes and crossover lines in order to connect the No. 1 Loop directly with the No. 16
Osakako Route of the expressway network.
Because the reconstruction site is located within a main trunk road site, restrictions were imposed on reconstruction execution width, and reinforcement of existingbridge columns, required to widen the roadwidth, was difficult to undertake. Then,
bridge columns integrated by multiple steel
pipes were newly constructed between theexisting bridge columns to make the newly-installed bridge column positively bear
horizontal forces occurring during earthquakes. To that end, the prescribed seismic
resistance could be secured for Nishisenba Junction without the reinforcement orreconstruction of existing bridge columns
and by changing the structural system of
the entire highway bridge structure.
Directions in Design to Ensure
the Seismic Resistance of Existing Highway Bridges
Stoppers were installed in the bridge columns integrated by multiple steel pipes
Fig. 1 Image of Horizontal Force
Bearing System that Applies
Bridge Columns Integrated byMultiple Steel Pipes

to bear only the horizontal force during
earthquakes, and the vertical load wasborne only by existing bridge columns(Fig. 1). In the bridge column integrated
by multiple steel pipes, the shear panel
was arranged on the horizontal tie beam,
and a damage control design was introduced with the aim of the absorption andcontrol of seismic energy during earthquakes. The horizontal seismic force to beborne by the existing bridge column was
reduced by the replacement of the bearing of these columns and other measures.
Capitalizing on the measures mentioned
above, a “Seismic Performance Level 2”that can withstand Level 2 Seismic Motions (strong seismic motion with extremely low occurrence frequency during the service of the structure) was able to be secured
for Nishisenba Junction without the reinforcement of existing bridge columns.
Compact Design of Foundation
Structures
For the foundation structure for use for thebridge column integrated by multiple steel
pipes, a socket-type bridge column integrated by multiple steel pipes with directly
connected pipes was adopted in which theFig. 2 Image of Bridge Columns
Integrated by Multiple Steel
Pipes with Directly Connected
Pipes
Width enlarging section

bridge column is inserted into a pile with adiameter larger than that of the bridge column and concrete is filled into the gap between the bridge column and the pile. The
adoption of this type of foundation has allowed for smoother force transfer to thefoundation and has realized a compact foundation structure without a footing. (Fig. 2)
Erection of Bridge Columns
Under the site conditions of a narrow execution yard and strict restrictions on overhead clearance, an erection platform wasinstalled in joining the foundation piles andbridge columns to secure erection accuracy,
and at the same time advanced execution
control was carried out in the erection andjoining of the column not only to prevent
contact with the girders of the expressways
in service but also to secure the prescribed
quality. In this way, this reconstruction project to improve the seismic resistance of theexisting bridge columns at the Nishisenba
Junction was safely and successfully completed. (Refer to Photos 1~5). ￭Photo 1 Installation of Photo 2 Erection oferection platlower column
form on levelling concrete

Before reconstruction

Existing bridge column
Section
After reconstruction
Newly-installed bridge column integrated
by multiple steel pipes bears loads
occurring during earthquakes

Newly-erected bridge column

Section

15 Steel Construction Today & Tomorrow April 2019

Steel pipe

Horizontal
tie beam(shear panel)

Photo 3 Erection under Photo 4 Erection using
low overhead
two 60-ton
clearance
cranesPhoto 5 CompletionJSSC Commendations for Outstanding Achievements in 2018-Thesis Awards

Loading Tests in the Large Deformation
Range for RHS Columns with Different
Manufacturing Processes

Prize winners: Seiji Mukaide, Nobuyuki Oku, Katsuya Matsuo and Motohide Tada
Seiji Mukaide

2002: Finished Graduate Schoolof Engineering, Osaka
University
2002: Entered General Building
Research Corporation ofJapan (GBRC)

2005: Assistant Professor, Osaka University
2016-: Associate Professor, Osaka Institute ofTechnology

In the current study, in order to clarify
the collapse mechanism of buildings andthe strength deterioration behavior ofsteel frames during collapsing, we conducted loading tests in the large deformation range for rectangular hollow section(RHS) columns-in the range where thestrength significantly deteriorates due tolocal buckling. The aim was to investigate the strength deterioration behavior
of RHS columns produced by employing different manufacturing processes. In
addition, we proposed a restoring force
model with easy applicability, and compared the results obtained in the test withthe proposed model to verify the performance of the proposed model.

RHS column manufacturing process,steel grade, width-to-thickness ratio, axial force ratio n, loading hysteresis andloading direction, and a total of 25 test
specimens were used. The loading method applied was the flexural shear loading
under constant axial force and the drift
angle θ was 0.3 rad, the loading limit
value.
Fig. 1 shows examples of the relationship between the dimensionless member end bending moment M/Mpc and themember drift angle θ (monotonic loading). Any specimens show strength deterioration due to local buckling. As shownin Photo 1, the local buckling conditiondiffers depending on the specimens applied, and it is understood from the photothat the local buckling in which the flexural compression side surface gets dented develops only by one wave in most
specimens with a loading direction of 0
degree.

Outline of Loading Tests
The parameters used in the test were theComparison between Existing
Analytical Models and Practical
Behaviors
The skeleton curve proposed by
Kato and Akiyama is cited as a restoration force model that takes into

Fig. 1 Relationship between Dimensionless Member-end Bending
Moment and Member Drift Angle

Fig. 2 Comparison between Test
Results and Proposed
Model

1.5
1.0

M/Mpc

Press forming (0 degree)
Press forming (45 degrees)
Roll forming (0 degree)
Corner welding (0 degree)
P2500
R2500

0.5
0.0
2.0
1.5

0

0.05

0.1
0.15
0.2
(a) D/t = 25, n = 0

M/Mpc

P2525-45
B2525
P2525
R2525

1.0
0.5
0.0

0

0.05

(rad)
0.25 0.3

0.1

0.15

0.2

D/t = 25, n = 0.25

2.0
1.5

account the strength deterioration caused
by local buckling. We proposed an analytical model prepared by the revision of
the above model. Fig. 2 shows a comparison between the revised analytical model and the test results. As can be seen in
the figure, the revised analytical model
can appropriately evaluate strength after
the strength deterioration reaches about ahalf of the maximum strength.
Conclusion
The knowledge obtained in the current
study is enumerated in the following:• Experimental confirmation of the behaviors of RHS columns in the large deformation range in which strength deteriorates significantly• Proposal of an analytical model prepared by revising the existing analytical model that can comparatively simply
express the behavior of strength deterioration due to local buckling, and confirmation of improvements to the measurethat can appropriately deal with practical strength deterioration behavior by theuse of the proposed analytical model ￭Test Model
D/t = 19
D/t = 25
D/t = 33
M/Mpc

1.0

0.5

/c p
0.0
0
10
20
30
40
(a) Roll formed products, n = 0.25
2.0
1.5

M/Mpc

1.0
(rad)
0.25 0.3

0.5

0.0
0

10

20

30

/c p
40

(b) Press formed products, n = 0.25

Photo 1 Deformation conditions
April 2019 Steel Construction Today & Tomorrow 16

-Thesis Awards

A Trial on Improvement of Fatigue
Crack Detection of Eddy Current Test by
Applying C-scope Imaging

Prize winners: Yusuke Koto, Takuyo Konishi, Chitoshi Miki and Hidehiko Sekiya

2011: Seconded to Atec Co., Ltd.
2013-: Doubled as Assistant Fellow, Advanced
Research Laboratories, Tokyo City University

approach with a detection efficiency muchhigher than that of MT. However, ET offers some problems such as difficulty inunderstanding flaw detection results andlow performance in the recording and reproduction of flaw detection results in narrow spaces and unstable weld surface inbox welding. (Refer to Fig. 1) As a result,
ET has not yet been applied in the inspection of fatigue cracks in steel bridges.

sonal computer, and the flaw detection results are subjected to image processing toconfirm the detection results. The change
in phases can be displayed in colors, andthe change in voltages amplitudes can bedisplayed in the length of color line in thenormal direction of the scanning locus,
which has thus made it possible to visuallyconfirm the changes in impedances in thedetection position. (Refer to Fig. 3)

Predominance of Eddy Current
Flaw Detection Tests
In the inspection of steel bridge fatigue
cracks occurring in weld beads, the magnetic particle test (MT) is commonly applied. However, MT is an approach that
requires the treatment of coating films,
spraying magnetic powder and magnetization, and further there are cases in which
the arrangement of magnetization devices becomes difficult in narrow spaces andcomplex-shaped weld joints.
On the other hand, the eddy current flaw
detection test (ET), a non-destructive inspection approach similar to MT, can easily detect flaws in coating films, and is an

Imaging of Flaw Detection Results
In the current study, we have developed asystem that can simply and accurately detect weld flaws such as fatigue cracking bymeans of C-scope imaging. Specifically, inthe developed system, information on voltage and phases that display changes in impedances is taken out and combined withposition information, or the information
thus obtained is converted to C-scope images.
The developed system is composed ofa general-purpose eddy current flaw detection device, an encoder to obtain position
information, a probe holder to improveflaw detection scanning stability and a per-Improved Performance in Weld Fatigue Crack Detection
With C-scope imaging, it has become possible to understand the information on not
only flaw detection signals in sound weldzones and the separation of crack detection signals from the above signal but also crack positions, which has led to thesolution of problems with ET. The application of the developed system is expected
to contribute towards a reduction in detection costs and the improvement of recording performance, objectivity and weld flaw
detection efficiency. ￭Yusuke Koto

2007: Graduated from Advanced
Course of The National
Institute of Technology,
Akashi College
2007: Entered Oriental Consultants Co., Ltd.

Fig. 1 Display of Eddy Current Flaw Detection Results

Fig. 3 C-scope Imaging of Flaw Detection Results
Dotted lines: Maximum voltage of flat plate specimens(a) No crack(b) Crack (1.0 mm depth)

Length of color lines : Voltage
Color : Phase

Fig. 2 Developed System
Encoder

Crack position

Probe holder
d=0 mmd=0.5 mm

Encoder

d=2.5 mm
Probe

Connecting PC and detector

17 Steel Construction Today & Tomorrow April 2019

d=5 mmJSSC International Events

IABSE Young Engineers Colloquium in East Asia

The 1st IABSE Young Engineers Colloquium in East Asia was jointly organized by
the Japanese, Chinese, and Korean Groupsof IABSE. The colloquium was initiated byProfs. Shunichi Nakamura, Limin Sun andHyun-Moo Koh in April 2018 and was heldon Oct. 24-25 2018 in Shanghai (Photo 1).
The Japanese Society of Steel Construction(JSSC) serves as a secretariat of Japanesegroup of IABSE (International Associationfor Bridge and Structural Engineering).
Major Aim of IABSE Young Engineers Colloquium
Many young engineers want to participate
in the IABSE congresses and symposiums,
which provide good and educational opportunities for them. However, these events
are held world-wide and not affordable forthem all. It is, therefore, desirable to haveregional colloquiums for young engineers
in East Asia which provides the same outcomes with much lower cost both in travel
expenses and registration fees. Furthermore,this event encourages young engineers to be
more actively involved in IABSE activities.
The organizers intend to keep this eventin small size so that participants have sufficient time to enable deep academic exchange at feasible schedule, which makes
this event sustainable. Eventually, this colloquium offers young engineers the opportunity to present interesting researches, projects
or construction practice to an audience of senior structural engineers and researchers.
Outline of 1st IABSE Young Engineers Colloquium
The program includes a keynote lecture
and three technical sessions on the first day,and the technical tour to four places of interests in Shanghai on the second day. The
keynote lecture, titled “Form and Functionin Design of Bridges”, was given by Mr.

Naeem Ullah Hussain (Photo 2), Director/
Global Bridge Leader of ARUP. The lecture based on his experience of design andconstruction of the actual bridge projects
including the Stonecutter Bridge (HongKong) and the Øresund Bridge (Denmarkand Sweden) was useful and educational
for young engineers.
At the technical sessions, a total of 22
young engineers (9 from Japan, 8 from
China, and 5 from Korea) presented interesting research papers and technical reportsof construction projects. The topics include
damaged bridges in Kumamoto Earthquake, development of new TMD, proposal of new type of bridge, structural designof new national stadium in Japan, evaluation of ERW pipe structural performance,
push-out tests of PBL strip, steel fiber reinforced PFC beam, application of new materials to structures, performance of box
girders subjected to thermal history due
to fire, wave loads acting on water foundation, training general bridge damage detection deep net, design and construction of
actual bridge projects, and so on.
There was a total of 50 participants, including 22 young engineer speakers, 18
experts and 10 audience from Japan, China, Korea, and Hong Kong. After the presentation, the presenters were all on stage
back and Q&A and discussions were carried out between young engineers and senior structural engineers and researchers at
each session, which was very active (Photo 3). They also exchanged information on
the latest technologies and knowhows withother engineers throughout the colloquium.
Presentations are evaluated by qualityof paper, quality of presentation and Q&A
and, in addition, age of presenters. One ofthree winners of the Outstanding Young
Engineer Best Paper Award was Mr. Yusuke Takahashi (Photo 4), Osaka Instituteof Technology.
The 2018 IABSE Colloquium Shanghai was organized with Chairs of three national groups, Profs. Yozo Fujino, Yaojun
Ge and Ho-Kyung Kim, and Committee members consisting of experts in three
countries. The Colloquium is characterized
by the following four features.
• Affordable. The registration fee is as low
as 8,500 yen including lunch and banquet,
which is about 1/10 of the usual symposium.
Small
Size. The small number of present•
ers allows longer discussion with deeper
exchange. This also leads to inexpensive
venue cost and less organization efforts.
Deep
Exchange. This event allows 10-min•
presentation and 20-min discussion for eachsession. Academic exchanges are madethroughout the Colloquium.
Young
Engineer Oriented. Speakers are•
all young engineers and all the events are
aimed at them. Senior engineers encourage discussions and give advice to young
engineers.
It is announced that “The 2nd IABSE Young Engineers Colloquium in East
Asia” will be held at Tokyo Institute ofTechnology, Japan, on 7th and 8th November 2019.
(Prepared by Shunichi Nakamura, Tokai
University, Vice President of IABSE)

Photo 2 Keynote lecture by Naeem Hussein

Photo 3 Discussion with presenters and audience

Photo 1 Presenters and participants

Photo 4 Presentation by Mr. Y. Takahashi
April 2019 Steel Construction Today & Tomorrow 18

PSSC2019
The 12th Pacific Structural Steel Conference (PSSC2019) will be held at the Tokyo
Institute of Technology in Tokyo from Saturday November 9 to Monday November
11, 2019. It will be organized by the Japanese Society of Steel Construction (JSSC).
This conference is hosted every three
years on an alternating basis amongthe 11 nations of the Pacific Council of
Structural Steel Associations. The 12th
conference will be the first one held inJapan since the third conference about
30 years ago in 1992.
In the conference titled “Steel Structureswith Resilience and Sustainability,” diverse
technological issues that many nations arefacing will be shared among the participating nations-natural disaster prevention
and control technologies, longer service lifeof infrastructure and the maintenance andrenewal of infrastructure. In this regard, it isbelieved that the conference will provide agood opportunity to deepen exchanges between Japanese and overseas experts relating to these issues. The keynote addresses
are planned to deliver by inviting worldwide authorities in this field.
The PSSC2019 is expected to serveas the venue for reporting papers andexchanging opinions pertaining to steel
structures in an interdisciplinary fieldcovering from civil engineering to building
Category

Registration fee– Regular– Student– Accompanying person– Media

construction. To that end, JSSC is hopingthat many people will participate in the
PSSC2019.
For more details, refer to the following:
Website:http://pssc2019.jp/•
Inquiry:
pssc2019@ec-intl.co.jp•• Conference: 9 (Saturday) to 11 (Monday) November, 2019
Banquet:November 9 (Saturday), 2019•Technical
tour: November 11, 2019•
(Planned visit sites: Facilities of the
Olympic and Paralympic Games Tokyo 2020 and renewal project for Metropolitan Expressway)
Registration
fee and other fees (See the•table below)
Early-bird
registration
April 1 to June 30
2019 (JPY)

Late/On-site
registration
July 1 to October 102019 (JPY)55,00020,0005,000
Free60,00025,0005,000
FreeBanquet– Regular– Accompanying persons

12,0007,000

Technical tour

2,000

Message from Chairman of International Committee
Hiroshi Katsuchi, Chairman, International
Committee of Japanese Society of Steel
Construction (Professor, Yokohama National
University)

The Japanese Societyof Steel Construction(JSSC) has conducted a wide range of activities in the form ofsurveys, research andtechnological development aimed at promoting the spreadof steel construction and at improving
associated technologies, and at the sametime has extended cooperation to related overseas organizations. With the aimof spreading Japanese steel construction technologies overseas and developing overseas markets, the Internation-

al Committee of JSSC was responsible
in editing the No.56 issue of Steel Construction Today & Tomorrow.
Issue 56 features outstanding Japanese technologies utilized for ongoingsteel-structure projects in the Tokyo area. Among the projects introduced in
the feature articles are a large-scale renovation of the more than 50-year old
section on the Metropolitan Expressway
and the construction of new athletic facilities related to the Olympic and Paralympic Games Tokyo 2020 including
the New National Stadium. A technicaltour visiting these facilities is plannedat the PSSC2019 (12th Pacific Structural Steel Conference) to be held in Tokyoin November 2019.
In addition, a special article-façade

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
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

design using stainless steel in a highrise building of TOKYO MIDTOWNHIBIYA-is also introduced. Further,
this issue introduces the JSSC Commendations for Outstanding Achievements in 2018: JSSC awards for excellent steel construction and thesis.
Regarding JSSC’s international
events in 2018, the 1st IABSE Young
Engineers Colloquium in East Asia heldby IABSE (International Associationfor Bridge and Structural Engineering)in October 2018 in Tongji University in
China is reported.
Finally, we would like everyone tocontinue to understand the activities of
JSSC and we would also like to hear
your opinions at any time.

© 2019 The Japan Iron and Steel Federation
Edited byCommittee on Overseas Market Promotion, The Japan Iron and Steel Federation
Chairman (Editor): Kei Teshima
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.