No. 61 April 2021

STEEL CONSTRUCTIONTODAY & TOMORROW

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

Special Issue

Japanese Society of
Steel Construction
Feature Article: Natural Disasters-Restoration and Countermeasures

1 Airport Access Bridge
5 Railway Facilities

3 Long-period Pulse-type Earthquake

7 Emergency Bridge

Special Article: Stainless Steel

9 Fukuoka Lawyer’s HallJSSC Commendations for Outstanding Achievements in 2020

• Outstanding Achievement
Awards

11 Aichi International
Exhibition Center

12 The Okura Tokyo
13 DaiyaGate Ikebukuro• Thesis Awards

14 Elasto-Plastic Analytical Program with Generalized Plastic Hinge
for Steel Square Tube Column with Local Buckling

15 Mechanical Properties of Steels for Bridge High Performance

Structures Subjected to Heating and Cooling Processes Simulating Fire

16 Plastic Deformation Capacity of Pre-assembled Type Built-up
H-shaped Beam by Submerged Arc Welding

17 A Series of Studies on Repairs to Low-rise Braced Structures after
Disasters

JSSC Events

18 The First IABSE Online Conference 2020
19 Program to Foster Steel Construction Engineers
JSSC International Committee

19 Message from Chairman
Published Jointly by

The Japan Iron and Steel Federation
Rhombus pattern-polished stainless steel (see pages 9~10)

Japanese Society of Steel Construction

Feature Article: Natural Disasters-Restoration and Countermeasures (1)Kansai International Airport Access
Bridge-Restoration from Tanker
Collision in Just Seven Months
by Junichi Samizo, West Nippon Expressway Company Limited
Damage Conditions
On September 4, 2018, a tanker in mooring in the vicinity of the Kansai International Airport collided with the KansaiInternational Airport Access Bridge, also
known as Sky Gate Bridge R, due to violent typhoon winds, which caused serious damage to the bridge girders.
The Kansai International Airport Access Bridge with a total extension of 3.75
km serves as a highway/railway bridgethat connects the manmade island on
which the Kansai International Airport
is built with the opposite shore area. The
highway section is managed by West
Nippon Expressway Company Limited (NEXCO West). The center sectionof the bridge is a truss bridge with integrated construction for combined use forhighway and railway, and both end sections are composed of steel box girder
bridges of the separated structure for use
for each of highway and railway.
The tanker collided with the bridge
section in the vicinity of P2 of the highway bridge at around 13:40, September
4 (Fig. 1). Meanwhile, the highway had
been closed due to strong winds since
13:20.
On the next day after the tanker collision, visual surveys were made of thedamage condition. As a result, it was
found that two spans from A1 to P1 andP2 to P3 were severely damaged due tothe tanker collision (Photo 1).
In the collision section of the bridge,
the girder in the A1 to P1 span (90 m)
was dislocated in the lateral direction by
about 1.5 m at the P1 support section,

Fig. 1 Location of Kansai International Airport Access Bridge
Kansai International Airport Access Bridge(total length: 3.75 km)
KansaiInternational Bridge section to which a tanker collided
Airport island

Rinku JCT

Fig. 2 Bridge Section to which A Tanker Collided
Steel Steelsimple simple Steel 2-spancontinuous
box
box
box girder
girder girder

Airport island side
Highway bridge(inbound lane)
Railway bridge
Highway bridge(outbound lane)

About 1.5 m

About 0.5 m
About 4.0 m
Bridge section towhich a tanker
collided

Fig. 3 Section of P2 Bridge Pier
About
4.0 m

About
0.5 m
Concrete filling

Photo 1 Damage of P1-P2 girder
1 Steel Construction Today & Tomorrow April 2021

and the girder in the P1 to P2 span (98m) was also dislocated in the lateral direction by about 4 m at the P2 support
section (Figs. 2 and 3). In addition, thehighway bridge collided with the railway bridge due to the effect of the lateral movement of P1 to P2 girders to cause
the lateral-direction movement of therailway bridge by about 50 cm.
The pivot bearing was adopted forbearing support, and the upper shoe on P1
and P2 were completely separated fromthe lower shoe due to the girder movement. In the steel bridge pier, concrete
was filled up to the crest of the column
section, and while peeling-off of painting
was found, it was confirmed that the steel
plate caused no deformation.
Traffic Operations after Damage
As a result of an inspection of the inbound-lane bridge, it was confirmed thatthe bridge suffered no damage, and thenthe one-way alternating traffic of emergency vehicles started at 0:40 on September 5. Then, various improvements
were made of the median strip on thetruss bridge of the access bridge to installa crossover that connected the inboundand the outbound lanes. At 5:10 on September 7, two-way traffic using only the
inbound lane started.
Meanwhile, the railway bridge wasrestored by the railway operating company after the removal of the damaged
highway bridge to resume railway operaFig. 4 Range of Reuse of A1-P1 Girder
Remanufactureblock
BL5~BL7

Reuse block
BL1~BL4BL1 BL2

BL3

BL4

BL5

BL6 BL7

14,70018,433

18,20018,433

14,700 2,667

2,667

89,800
A1

P1

Photo 2 Removal of damaged P1-P2 girdertions on September 18.
Removal of Damaged Bridge
Girders
Because the bridge girders in the twospans from A1 to P1 and from P1 to P2
were severely damaged, it was decided that, first of all, the damaged girders
would be removed using a large-capacity
floating crane barge and that the restoration method then be worked out.
The floating crane barge Musashi (lifting capacity: 3,700 tons), Japan’s largest
class of its kind, was used in the removal of the damaged girders. The metal fittings for use for large block erection were
re-attached to the cut track of the attachment of the fittings that were used in theinitial erection of this access bridge.
The damaged girders in the A1 to P1
span were lifted and removed on September 12, and those in the P1 to P2 span on
September 14 (Photo 2). During removal, because the operations of the railway
and airport were not yet restored, the lifting/removal work could be done in thedaytime. The removed girders were loaded on the barge one by one, and the girder in the A1 to P1 span was transported to
the Wakayama Plant of TAKADAKIKO
Co., Ltd., and that from the P1 to P2 span
was transported to the Sakai Plant of IHI
Infrastructure Systems Co., Ltd.
Reuse and Remanufacture of
Girders
Detailed surveys were made of the removed girders at each plant. It was decided after the surveys that, in cases whenfractures and large deformations were
found in a girder block divided by splicesection, that block would not be reused.
As a result, in the total of 7 blocks of
the A1-P1 girder, 4 blocks were reused,and 3 blocks were remanufactured (Fig.

4). Regarding the P1-P2 girder, because
damage occurred on its entire length, thegirder was fully remanufactured.
In order to reduce the girder remanufacturing steps, the box girder configuration, steel floor slab thickness (12 mm)
and other basic structural details weresettled to those applied at the stage ofinitial erection. For the shop remanufacture of the girder (950 tons), 4 lines in
2 plants were allocated, shop assembly
was eliminated, and wall/handrail members were unitized, all of which led to reduced steps in remanufacturing.
Meanwhile, the bearing support was
subjected to a structural change from apivot bearing to a BP-P bearing, and thenthe bearing was remanufactured. The
steel finger joint that was significantly
deformed was also remanufactured.
Girder Erection and Full-scale
Restoration
The reused/remanufactured A1-P1 andP2-P3 girders were erected during thenights of February 13 and 14, 2019. Because the railway and airport had alreadybeen put into full operation, the erection time was restricted to nighttime. The
erection was carried out employing thefloating crane barge used in the removal (Photo 3).
After the girder erection, the expansion joint was installed, and the bridge
surface was paved. The operation of theoutbound lane finally resumed on February 27.
Then, the crossover used for twoway traffic was removed, and the median strip was restored. Finally, at 6:00 amon April 8, 2019, the full-scale restoration of the Kansai International Airport
Access Bridge from the tanker collision
was completed in the extremely short period of seven months after the collision.

Photo 3 Lifting of remanufactured P1-P2 girder from barge
April 2021 Steel Construction Today & Tomorrow 2

Feature Article: Natural Disasters-Restoration and Countermeasures (2)Long-period Pulse-type Seismic
Motions at Uemachi Fault and Exampleof Effective Countermeasures
by Yasuhiko Tashiro and Satoshi Yoshida, Nikken Sekkei Ltd.

Uemachi Fault Seismic Waves
In the peak period of the Holocene glacial retreat about 6,000 years ago, the sea level was
higher by 5~6 m than the current level. In
those days, most of the area of the current Cityof Osaka was sunken in the sea that spread to
the west edge of the Ikoma mountain range as
the Kawachi Bay in those days. Also in thosedays, the Uemachi plateau was a narrow peninsula that struck out from south to north.
The present-day Uemachi plateau is about
25 m above sea level, and its west side abruptly falls. When observing the undergroundcondition of the Uemachi plateau, there is agreat difference in terms of the initial-stage
marine clay Mal layer emergence levelabout 400 m between the Uemachi plateau
surface and the Osaka Bay coast. The plateau
has undergone upheavals over a long periodof hundreds of thousands of years due to theactivities of the Uemachi fault zone that traverses Osaka from north to south. How many
fault activities and how huge an earthquake
has the Uemachi plateau experienced to reachits current form? Looking at the topography
on and in the ground, one cannot help but
imagine its tremendous history of formation.
Since the occurrence of the Great Hanshin
Earthquake in 1995, concerns about guarding against an Uemachi fault-induced earthquake has grown among citizens in Osakaand has steadily become conspicuous. Since
2000, studies have made rapid progress on
the prediction of the strong seismic motions
that are assumed to occur in a hypocentral
fault, and in 2006 the Committee on Comprehensive Countermeasures against Natural
Disasters” established by the Osaka Prefectural Government and the City of Osaka prepared a report “Assumptions of Large-scale
Disaster” based on the strong seismic motion
prediction results obtained by assuming theactivities of several inland active faults.
3 Steel Construction Today & Tomorrow April 2021

Fig. 1 Flat-type Seismic Motion GroupsV (cm/s)

In the report, 35 cases of hypocentral
regions were assumed for the Uemachi
fault zone-induced earthquakes, and simulated seismic motion waveforms (predicted seismic waves) were obtained for every 500 to 250 m-mesh zone of the City ofOsaka area pertaining to each of its 35 hypocentral regions. The number of predicted strong seismic waves in the report totals
about 110,000 in the City of Osaka area.
In 2009, the “research group on seismic motions for building design and design
methods to resist an inland-type earthquake
in Osaka” (research goup1)) was inaugurated
as an industry-public-academia joint researchorgan with the Kansai Branch of JSCA (Japan Structural Consultants Association) as its
secretariat. The “research group” has aimed
at preparing design seismic motions based on
the predicted seismic waves prepared by theCity of Osaka and Osaka Prefectural Government. It analyzed the response spectrumof 110,000 seismic waves and as a result notified that the waveform can be classified into
two types: flat-type seismic motion in an entire cycle and pulse-type seismic motion in along-period sphere. (Figs. 1 and 2)
Long period-type seismic motion is frequently observed in the end of fault fracture
direction, or in the wave advancing direction sphere, which coincides with the “directional pulse” (Fig. 3) occurring due to theadvancing-direction composition (Doppler
effect) of the waves generated at each zone.
An outline of the design input seismic
motions publicly released by the “researchgroup”1) in 2012 is introduced below:• Area: Division of City of Osaka
Area to 6 Zones (Fig. 4)• Level: Settlement of 3 Levels forLevel 3 Seismic Motion-Level 3A: Average level-Level 3B: Level incl. about 70 percentile of predicted seismic motions-Level 3C: Level incl. about 85 percentile• By Type of Seismic Motion: Settlement of 2 Types by Zone
-Seismic motion ①: Seismic motion
with flat-type spectrum characteristics (flat type)

200
100
0
0.1

1.0

10

Time (sec)Fig. 2 Long-period Pulse-type Seismic
Motion Group
900
800
700
600
sV (cm/s)

The Uemachi fault traverses the City of Osaka
area from south to north, where an inland-type
earthquake is forecast to occur with the Uemachi fault zone as a hypocenter. This long-period pulse-type earthquake and a high-risebuilding constructed by incorporating effective countermeasures are introduced below:

Average
+

500
400
300
200
100
0

0.1

Average
1.0Time (sec)10

Fig. 3 Conceptual Drawing of
Directional Pulse

Time (sec)Fig. 4 Zone Division in City of Osaka
Area-Seismic motion ②: Long-period pulsetype seismic motions selected fromamong predicted waves (pulse type)（Refer to Fig. 5）

Fig. 5 Uemachi Fault Waves Analyzed
by research grioup1)
Maximum response spectrum
inclusion drawing (①+②)
300sV (cm/s)

250
200
150
100
50
0

0

350

1.5×”Notified wave” in “Notified wave” inBuilding Standard Law Building Standard Law
of Japan (foundation)of Japan (foundation) 3B
1
2
3
4
5
6

Time (sec)sV (cm/s)

300

Table 1 shows the seismic design criteria
to treat great and maximum earthquakes(excerpt). The Uemachi default seismic
wave of the “research group”1) introduced
above is treated as the seismic wave ofLevel 3 maximum earthquake in the table.
In order to treat Level 2 seismic motion, the inter-story drift angle of the structural member adopted for this building issettled at 1/150 or lower, which showshigh seismic performance of the building.

• Verification of Effect of Intensive

250
200
150
100
50
0

• Seismic Design Criteria

0

1.5×”Notified wave” in “Notified wave” inBuilding Standard Law Building Standard Law
3C
of Japan (foundation)of Japan (foundation)
1
2
3
4
5
6

Time (sec)

Example of Building Employing
Effective Countermeasures• Outline of Building and Structure
Name: Nakanoshima Festival Tower
West (Photo 1)
Project owner: The Asahi Shimbun
Company, Takenaka Corporation
Location: Nakanoshima, Kita-ku, Osaka
Applications: Hotel, office, art museum, shop
Total floor area: 151,000 m2
Height: About 200 m
No. of stories: 41/-4/P2
Structure: Seismic-response structure,
S/SRC/R structure
Construction term: July 2014~March 2017
Fig. 6 shows the framing elevationand damper arrangement. The building iscomposed of a response-control structureand features a low-rise floor-intensive response-control structure in which large-capacity oil dampers with a maximum damping capacity of 6,000 kN are arranged
intensively in the low-rise section in addition to the arrangement of oil dampers inside the standard floor center core.

Response-control System
Fig. 7 shows the comparison of responses(Level 2 “notified wave”) between the installation of intensively damper-arranged
low-rise floors and no installation. It is understood from the figure that the response isimproved at floors other than low-rise floors.

• Result of Response to Uemachi

Fault Wave of the “researchgroup”1)
Fig. 8 shows the maximum inter-story drift
angle to the Uemachi fault wave (3B) of the“research group”1). In this building, the maximum inter-story drift angle reaches 1/75
and the layer plasticization rate reaches 2.0 at
its maximum, which thus satisfy the need fordesign criteria for Level 3 seismic motion.
♦♦♦

Specific features of long-period pulsetype seismic motion lies in that the number of waves is less and that a building
having a period longer than the pulse period suffers from great ground displacement
as if the footing is lost. Currently, any established countermeasure against long-period pulse-type earthquakes is unavailable,
and thus example of effective countermeasures against long-period pulse-type earthquake adopted in a highly seismic-resistant building was introduced above.

Office floor:
Outer peripheral
column @3.6 m
1st to 4th floors:
Intensive
responsecontrol
layer

Photo 1 Nakanoshima Festival Tower West6,000-kN
oil damper

Installationof intensively
damper-arranged
low-rise floor

40
35
32
30

No installation of
intensively
damper-arranged
low-rise floor

25

Improvement of

20 response of upper

floors during earthquake
due to intensive response
15 control at low-rise floor
10

5

1
B3

0

2

4

6
8
Inter-story drift angle

Fig. 8 Response to Uemachi Fault
Wave 3B (“research group”1))
PH1 Floor
40
35
32
30
25
20
15

1
B3

0

2

4

6 8 10 12 14 16Inter-story drift angle (×103 rad)

Table 1 Seismic Design Criteria (Excerption)
Earthquake Level 2 seismic motion Level 3 seismic motion
scale(great earthquake)(maximum earthquake)5th-floor
truss

Wave
adopted6,000-kN
oil damper
BigWallTargetcriteria
for upper
floors

N

Floor

PH1

5

32nd-floor
truss
Center core:Oil damper(2,000 kN)

Fig. 7 Comparison of Responses
between Installation ofIntensively Damper Arranged
Low-rise Floor and No Installation

10

Fig. 6 Framing Elevation andDamper Arrangement
Hotel floor:
Outer peripheral
column @4.5 m

Reference1) “research group on seismic motions forbuilding design and design methods to resist an inland-type earthquake in Osaka”

Notified wave×1.5“Notified wave”
Uemachi fault wave ofObserved wave
“research group”1): 3B
Site wave
Elastic limit strength:
Ultimate strength or(1. 1F-Z) or lower
Inter-story drift angle: lower
1/150 or lower

E

April 2021 Steel Construction Today & Tomorrow 4

Feature Article: Natural Disasters-Restoration and Countermeasures (3)Heavy Rain/Heavy Snow/Strong
Wind Disasters in Railways andCountermeasures
by Ryota Sato, Railway Technical Research InstituteRailways are composed of many facilities such as rolling stock, track and electric train overhead wire, and accordingly
the kinds of railway disasters that sufferfrom meteorological phenomena are diverse. Focusing on heavy rainfall, heavy
snowfall and strong wind, the kind of disasters that railways suffer and an outlineof hardware and software countermeasures against these disasters are introduced below:
Heavy Rainfall Disasters in Railways and Countermeasures
In Japan, the annual precipitation isabout twice the world average, and themountainous region accounts for threefourths of national territory. As a result,not only slope collapse and other sediment disasters but flooding and other river disasters occur during rainfall almost
every year. The sediment and river disasters and countermeasures taken in railways are outlined below:• Sediment Disasters

In examining the countermeasure against
sediment disaster, it is necessary to understand the features peculiar to eachtype of disaster.
Specifically, in the case of embankment collapse, the groundwater level rises due to rainwater penetration to cause alowering of the strength of the embankment, which is cited as a main cause forembankment collapse. In the collapseof the embankment, the amount of collapsed soil reaches several hundred cubic meters1). On the other hand, the debris flow that occurs during heavy rainscauses the soil to contain a large amountof water and become fluid, causing damage over a wide area. In debris flows,
the amount of collapsed soil can reach
100,000 cubic meters2).
Among hardware countermeasuresagainst collapse of the embankment are
drain pipe installation (Fig. 1)3) and slope
improvement to prevent embankment
collapse. Among hardware countermeasures against debris flow are debris bar5 Steel Construction Today & Tomorrow April 2021

riers and channel improvement. Furthermore, as a software measure, railway
operations are regulated according to theamount of rainfall.

• River Disasters

Disasters caused by the rise of river water levels are divided into disasters ofbridges and revetments. Major causes
for these disasters are the scouring ofbridge piers or embankment wall foundations and the lowering of riverbeds.
When scouring or lowering progresses,
there are cases in which the stability ofbridge foundations falls and bridge piers
fall down.
Among the hardware countermeasures against these disasters are themethod in which heavyweight materials are installed on the river bed in thevicinity of bridge piers, and the method
in which the periphery of bridge piers issurrounded with heavyweight materials
to prevent fall down even when scouring progresses (Fig. 2)4). Furthermore, asa software countermeasure, railway operations are regulated depending on theriver water level.

lines. Avalanches and snow accretion
to vehicle and countermeasures are outlined in the following:• Snow Avalanches

Snow accumulated on slopes is affected by various meteorological effects tocause changes to the accumulation depth
and properties of accumulated snow, andthus there are cases in which snow avalanches occur. The occurrence of avalanches along railway lines sometimes
brings about serious disasters such as
the overturning of running trains and destruction of railway facilities.
Among the hardware countermeasures against avalanche disaster are avalanche prevention forests and fences thatprevent avalanches from occurring, as
well as retaining walls, snow sheds that
protect railway tracks and trains from avFig. 2 Basic Practice ofScouring-prevention Work

Avalanche and Snow Accretion
Disasters in Railways and Countermeasures
About 40% of Japan’s total railway lines
of about 28,000 km are laid in heavy
snowfall areas, and thus snowfall disasters have occurred on many railway(a) Foot protection work
Hakama(Protection workaround pier)(b) Hakama work

Fig. 1 Outline of Drainage Measure
Employing Drain Pipes

Protection work
Drain pipe(a) Installation on slope

Drain pipe

Stagnant rainwater(b) Installation on roadbed(c) Concrete lining
Dam(d) Ground sill work

Fig. 3 Major Countermeasures against Avalanche
Snow cornice prevention fence

Piles

Suspension
frame

Preventive
fence

Steppedterraces

Avalanchewedge
Avalanche
deflecting
structure

Avalanche breaking
structure

Prevention
forestRetaining wall

Protection
fence

Earth
mound
Snow shedalanches (Fig. 3). Furthermore, as a software countermeasure, railway operations
are regulated depending on new snowfall
amount, temperature, rainfall and otherguidelines.

• Snow Accretion to Vehicle

Snow flying up from the track during
train running adheres to the bogie. Whenthe adhered snow drops due to temperature changes and vehicle vibration during train running, there are cases inwhich the aboveground facility is damaged by the snow falling impact.
Among the hardware countermeasures against snow accretion are measures taken aboveground in which theflying snow is suppressed by sprinkle water on the track and changing tohigh moisture snow (Fig. 4). On the other hand, the vehicle suppresses snow accretion by flattening the underfloor. Furthermore, as a software measure, railway
Fig. 4 Countermeasure against Flying
Snow by Means of Water
Sprinkle on Track
Sprinkler

Application example ofsnow shedoperations are regulated according to theamount of snow depth on the tracks.
Strong Wind Disasters in Railways
In Japan, not only strong winds blow inlarge areas such as monsoons and typhoons, but also gusts may blow in small
areas such as tornadoes. The derailment
and overturn of trains due to these strong
winds and countermeasures are outlinedin the following:
The derailment and overturning oftrains caused by strong winds occur
when strong wind force working on the
train surpasses the train’s resistance tothe strong wind. The weight and runningspeed of trains, the structural type oftrains and many other elements affect theoccurrence of derailment and overturn.
In order to prevent overturn due tostrong winds, wind-prevention fences arearranged in areas where strong winds blow
due to topographical conditions (Photo 1).
Furthermore, as a software measure, railway operations are regulated according to
the amount based on measurement values
obtained from anemometers (3 cup-type
and propeller-type, see Photos 2 and 3).
Towards Improved and Stabilized
Railway Operations
Of the meteorological disasters the railway suffers, heavy rainfall/snowfall- andPhoto 1 Example of wind-preventive fence

strong wind-induced disasters and countermeasures are outlined above. Because
the types of disasters will be affected byclimate changes forecasted to occur inthe future, the scale and frequency will
be likely to change.
Along with the development of observation technologies employing meteorological radar systems, it has recently become possible to understand wind,rainfall, snowfall and other external meteorological forces in a multi-faceted andhighly resolution level by the use of radar systems5) 6). Further, the accuracy of
external meteorological force forecasting is being improved due to advanced
calculation technologies and enhanced
calculation speed.
We consider that the examination of
how to effectively apply these advanced
countermeasures to be obtained by capitalizing on these advanced observation andforecast technologies will be useful forsafer and more stable railway transport.
References
1) O. Nunokawa et al: Forecast method forcollapsed earth on railway embankmentand earth cut due to rainfall by meansof statistical approach, Journal of JSCE,
Vol. 65, No. 3, 728-744, 2009
2) Nara Prefecture: Survey and research report on large-scale sediment disasters in2011 Kii Peninsula Major Flood Damage, 20153) Railway Technical Research Institute:
Maintenance standard and recommendation on railway structures (structures),
Maruzen, 2007
4) Railway Technical Research Institute:
Maintenance standard and recommendation on railway structures (structures),
Maruzen, 20075) C. Fujiwara et al: Study on gust detection
system using Doppler radar, JR EAST
Technical Review, No. 46, pp. 29-34,
20136) E. Nakakita et al: Development of early-stage detection and forecast system
for guerrilla rainstorm, Journal of JSCE,
Vol. 20, pp. 355-360, 2014

Photo 2 Three cup-type anemometer

Photo 3 Windmill-type anemometer

April 2021 Steel Construction Today & Tomorrow 6

Feature Article: Natural Disasters-Restoration and Countermeasures (4)Key to Traffic Restoration: Emergency
Steel Bridges-Importance andTechnical Developments
by Kazuhisa Fujii, Ministry of Land, Infrastructure, Transport and Tourism
Highways are an essential infrastructure used by everyone. They support
our daily life and economic activities
and, at the same time, when disasters
occur, highways are expected to playa key role in smooth emergency/rescue
operations, the transport of emergency supplies and other support activities.
To that end, when it is anticipated thathighways will suffer from disasters, restoration is required very quickly.
In order to restore the traffic function of damaged highways at an earliest stage, it is necessary to make full
preparations even before the occurrenceof disaster. In this regard, the emergency bridges with rapid construction design (a type of portable, prefabricated,truss bridge), one of these key preparations, is introduced in the following discussion.
Outline of Emergency Bridgewith Rapid Construction Design
When a bridge is damaged or washedout due to river water rise, earthquake,avalanche and other factors and its regular use becomes impossible, an emergency bridge is erected for temporary
use in order to secure the traffic function of highways quickly. The bridge
structural components prepared in advance are transported to the site where
the disaster occurs. The emergency
bridge can then be rapidly erected bymeans of component assembly.
Currently, a total of 30 emergency bridges are prepared at the Ministry of Land, Infrastructure, Transport
and Tourism (MLIT). They are stored
and maintained by the technical and national highway departments of respective MLIT Regional Development Bureaus located nationwide from Okinawa
to Hokkaido.
The type of emergency bridge currently in use is the truss type structurethat is easy to handle. Capitalizing on
the characteristic performance peculiar
to the truss bridge, the bridge can meetthe need for diverse lengths and spans in
7 Steel Construction Today & Tomorrow April 2021

conformity with on-site conditions andcan be erected by assembling prefabricated bridge components on site.
Example of Application of Emergency Steel Bridges
In a wide area extending from Kyushu toother adjoining areas, the 2020 Kyushu
Floods brought about a serious disasterthat resulted in damage to many human
lives, houses, lifelines, and local industries. Currently, the national governmentis promoting authorized disaster restoration projects in the area which extends
to approximately 100 km in length covering National Highway Route 219
along the Kuma River between Yatsushiro and Hitoyoshi, and the Kumamoto prefectural road. The restoration includes 10 bridges that were washed out.
Among the washed-out bridges was
the Nishise Bridge that spans the Kuma River on the Hitoyorshi-Minamata
prefectural road. This bridge serves asa lifeline road and school-access roadfor Hitoyoshi citizens. However, thebridge was fully closed as of July 4,2020 due to the washing out of a 43 mlong bridge girder, a center section of
the bridge having a total length of 174
m. Therefore, the school-access roadwas forced to detour to National Highway Route 219 where traffic is heavy.
To remedy this adverse situation, an
emergency bridge was provided for the
emergency restoration of the Nishise
Bridge. By September 4, this measure
led to successful resumption of the traffic function as not only a lifeline roadbut also a school-access road.
In this emergency restoration work,
an emergency bridge (assembly-type
Warren truss bridge) that was preparedby the Kyushu Technical Office of the
Kyushu Regional Development Bureau
was employed. Because the prepared
bridge could meet only a 40-m span of
the required 43-m girder span length,
the remaining 3-m section was manufactured in the prefabrication shop. In
the bridge erection, an en-bloc erection

method using a 500-ton crawler crane
was adopted due to the flood season
conditions, thereby avoiding an erection in which intermediate bents are installed. In this way, some devices wereincorporated to allow earlier erection.
On the assumption of the use over
several years, the existing bridge pierand the emergency bridge pier (bent)
were repaired using bolts to fortify an
integrated bridge pier so as to make it
difficult for the emergency bridge to be
washed out. In addition, a steel H-beamfor preventing driftwood collapse wasinstalled on the upper stream side of thebent so as to prevent a direct hit.
In the utilization of emergency bridges, the basic practice currently adopted
is to use emergency bridges owned byeach Regional Development Bureau ineach local region. However, in order tomeet the request for diversifying applications and renting to other bureaus, aflexible system has been adopted inwhich the bridges owned by one bureau
can be used by another bureau.
Towards the Smooth Applicationof Emergency Steel Bridges
A major requirement for emergency
bridges is that the bridge can promptly be erected at the disaster-stricken site
in an emergency. In order to allow for
prompt erection, it is essential to implement erection training, to hold training
courses and to carry out periodic inspections of bridges in storage at all times.
For the erection training and training
course, various devices are incorporated
by respective local areas, among whichis the joint offering of a training courseby the staff of the Regional Development Bureau. They collaborate on thistraining with the staff of local public organizations and with local construction
associations based on their disaster response agreements.
Further, through the implementationof erection training and training courses, it is important to nurture and secure
not only engineers and local construc-Earlier Traffic Restoration Employing Emergency Steel
Bridge (Nishise Bridge)
Dimensions of Nishise Bridge• Bridge length: 174.0 m• Type of bridge: 4-span steel simple truss bridge• Completion: 1967
174.000 m

44.000 m

43.000 m

43.000 m

44.000 m

A2

P3

P2

P1

A1

Washed-out section

Damage condition

P2

P3

Opening of emergency bridge

Erection of emergency bridgetion companies that can quickly respond in an emergency but also to locate human resources that can offer
cooperation during a disaster. It is also
important to increase the number of cooperative companies that can collaborate during a disaster.
New Technical Developments for
Emergency Steel Bridges
In the situation in which natural disasters frequently occur and the incidenceof terrible disasters increases, it will be
imperative to reliably secure highway
traffic immediately after a disaster. For
that purpose, a specific duty imposedon the engineers engaged in highway
maintenance is to make necessary preparations in advance so that emergency bridges can be erected as quickly as
possible as the need arises.
In order to meet the needs of diverse
erection conditions, expectations arehigh for new technical developmentsthat will lead to the rapid erection of

emergency bridges. Among these newtechnical developments are the further
unitization of steel bridge components,
minimized number of bolts applied forjoining components and reduced weightof steel members used for the emergency bridge. These developments must
proceed while maintaining the bridge’s
designated design load and allowing
for reduction of the period required for
emergency bridge erection. In addition,
the reduced weight of steel components
used for emergency bridges offers thepossibility to erect emergency bridges
in sites where large-capacity construction machinery cannot enter or be installed.
♦♦♦

Currently, socio-economic activities are
shifting towards the ostensible “just-intime system” of manufacturing which isbased on the principle of keeping inventory as low as possible and producing
only the amount of goods needed at aparticular time. At the same time, sup-ply chains are becoming more widespread and complex. Given this situation, the need to minimize the impact of
a disaster on highway networks, once it
has occurred, is of concern and the related social requirements are expected
to become even stronger in the future.
In order to be able to respond to theseneeds in the future, we would like to acquire help from the Japanese Society of
Steel Construction and also to promotecollaboration with those who are concerned in local public entities and construction industry-related associations.
As we thus intend to appropriately provide for remediation of disasters and to
take adequate measures in the event of
a disaster, we would like to ask for continued patronage and cooperation of allconcerned.

April 2021 Steel Construction Today & Tomorrow 8

Special Article: Stainless SteelFukuoka Lawyer’s Hall

-Stainless Steel for Interior and Exterior Achieving
Traditional Hakata Woven Pattern by Optimized Use of
Stainless Steel with Various Polishingby Koichi Furumori, Furumori Koichi Architects
Opened Lawyer’s HallWith the relocation of Kyushu University, three legal professional functions (court, public prosecutor’s office,lawyer’s hall) will gather at the placeof Ropponmatsu campus before, alongwith complex facilities and apartments.
Therefore, the lawyer’s hall was selected by a publicly-offered proposal. The
main point of the proposal statements
is that: “I want to emphasize a lawyer’s
hall open to society in order to comply
with the principle of the rule of law forsociety in general. It is the consistentattitude of this project to express lawyer’s aspirations in public.”
At the Entrance Hall, Fukuoka symbol’s Hakata-ori texture was emphasized right the way because it is the first
impressive of visitor, not only the local citizens but also foreigners. A step
sequence of brainstorm way can be described as below.
First, I got a cloth with a tribute pattern, pinned it on the wall of the office,and occasionally looked at it. ThenI found that the angle or direction inwhich a person looks at an object can
decide the differences of the motifs.
It is the “”Differences in perspective
viewpoint” or the “Variation principleof near and far in visual.” When I lookat it from a distance, a simple striped
pattern appeared. Approaching closer,
I recognized that as a rhombus pattern.
Certainly, it was one of the charms of
the Hakata-ori tribute pattern. Placing
related elements in close proximity andadding the stainless steel there, a stunning creative material was born. Here,we will introduce the process leading to
the realization of the Hakata-ori stainless steel texture.
(See Photos 1 and 2)
Collaborative Design
In recent years, in our design, we often think about cooperating with many craftsmen. By accumulating many technologies and knowledge, we
9 Steel Construction Today & Tomorrow April 2021

Photo 1 Full view of Fukuoka Lawyer’s Hall

aim to achieve the unique expression.
The process is called “Collaborative
design.” Until now, collaboration has
been carried out in all aspects of construction. The outstanding thing is thatthe person who is spending most oftime in manufacturing takes part in thedesign deeply.
This time also, we did set up a meeting together from the beginning of design process. We believe this combination will lead the project in the
spotlight as well as possible. An expert stainless steel polishing craftsmen
performed the detail of Hakata-ori
pattern in the mass steel excellently. It
has been over more than our expectation. A unique material was created inreality.
Stainless Steel• Target/What I Aim for
Until now, there have been several expressions of the Hakata-ori tribute
pattern, in term of the traditional woven pattern, with different colors suchas tiles and paint. However, this time,
I tried to convey the image of Hakata-Photo 2 Hakata-ori tribute pattern

ori tribute pattern through the type ofstainless steel polishing only, not by thedifference in color.

• Problem Definition

First of all, I wondered if I can reflect thecharacteristics of Hakata-ori tribute pattern, especially in the texture. Its look islike a stripe line in the distant view, but
the rhombus pattern gradually appears
when seeing closer. The work of this abstraction seemed to be extremely difficult. The most hard one is polishing therhombus texture. If the outline is blurred,
the attractiveness of the stripe will notdomly but do not break the rhythm aswell. Finishing material was merged inshining white silver pattern with 2 types(exterior and interior). Exterior one
used is highly corrosion-resistant ferritic stainless steel NSSC-220M. Interior
one adopted is environmentally friendly
white stainless steel NSSC-FW2.
(See Photos 5 and 6)
Photo 3 Rhombus pattern mockup• Surface Finish

As a result of making many prototypes
and very delicate examinations in a special manufacturing process of polishingor looking from remote and closed distances, a fine surface finish was successfully obtained. This surface finish is amere stripe in the distant view, but whenapproaching, a diamond-shaped expression appears. Finally, our team could reflect an historical silk texture regarding to this city, Hakata city, in term of
stainless steel. Generally, stainless steel
products are standardized, but it was
confirmed that by applying handmade
polishing, an abundant expression is created with many potential.

Photo 4 On-site mockup

be transmitted when viewed from a distance, and if the outline is sharpened, thetexture will not be understood clearly.
(See Photos 3 and 4)• Technology that Led to Solution

Conclusion
Looking at the building and the material that are standing on site now, it deeply impresses us. It is the result of manystudies and experiments that are not easy
to have chance to get an opportunity. Fukuoka Lawyers Association and Japan
Institute of Architects, who managed the
project, carefully planned and created anenvironment where we can concentrateon design. In addition, I am deeply grateful to Okumura Corporation, Nittetsu
Stainless Steel Corporation, Sanwa Tajima Co., Ltd., and Toyo Stainless Steel
Polishing Industry Co., Ltd. for deeply understanding their feelings and taking over the challenge. I can’t find any
words to express. I am really proud ofall.
Finally, when looking at the completed building, we can see that many craftsmen’s ideas have been merged together, and that strength and kindness coexist
in the space, thereby creating a varietyof potential elements. We hope that Fukuoka Lawyer’s Hall will lead to the understanding of lawyers and citizens andbecome the place that helps citizens introuble, and that it will gradually open
up the aspirational feelings of lawyers to
the citizens.

Photo 5 Exterior stainless steel

According to Mr. Kadotani, who tookcharge of stainless steel polishing in thisproject, he said: “In order to express thevertical stripe texture, which is the coreof the design, I adopted inhomogeneouspolishing. It is the latest technology to
abstractly express Hakata-ori tribute pattern.”• Specific Technology

There are three types of expression ofsolid vertical stripes:-”Buffing that gives the luster of stainless steel without glazing”-”Uneven vertical lines that are following the sharpness of Hakata-ori”-”Diamond polishing that is consciousof unique patterns”
The three types of polishing werecombined to 1 m panel widths. Then 10
patterns were created and arranged ran-

Photo 6 Interior stainless steel

April 2021 Steel Construction Today & Tomorrow 10

JSSC Commendations for Outstanding Achievements in 2020-Outstanding

Aichi International Exhibition Center(Aichi Sky Expo)

Prize winner: Takenaka Corporation
Features of Aichi International
Exhibition Center
This building was constructed by Aichi
Prefecture and is the first exhibition hallin Japan directly connected to an international airport. The exhibition area is oneof the largest in Japan at 60,000 m2, andExhibition Hall A is a pillar-less large
space with an exhibition area of 10,000
m2 and 100 m×100 m, and has a 20 mheight under the beam, allowing for music concerts to be held.
The five halls (Exhibition Halls B
through F) are large spaces with a heightof 14 meters under the beams, and can beused together to a maximum of 50,000
square meters.
With a large-capacity solar power
generation system and various energysaving technologies, it is the first exhibition hall in Japan to achieve CASBEE S
rank and ZEB Ready.
Outline of Structural Planning
The west wing, including Exhibition

Hall A, which is a column-free space ofabout 100 m×100 m, adopts a two-way
truss structure, and the truss pitch andtruss size are set based on the optimization study of the members. The truss columns are V-shaped to secure both interior space and MEP space.
In the east wing of Halls B through F,
six columns having knee braces are installed in each of the five 10,000 m2 exhibition halls with 14 m under beams.
These columns realize the rational single-layer roof frame with H-shapedbeam.
The 200 m-long large eave structureof the entrance is equipped with 45 vertical greening units, “Vertical Forest,”planned to bloom with seasonal flowers
throughout the year. For the wind pressure resistance and salt damage resistance specific to the building site, we devised a new greening structure systemusing SUS316, which contributes to theimpressive and symbolic design of theentrance space.

Entrance canopy of Aichi International Exhibition Center

Outline of the Vibration Control
Structure
Oil dampers were installed to reduce vertical movement. The vertical response
acceleration is reduced about 20-30%,
reducing the risk of falling of suspended objects for events in the exhibition
hall and improving the safety of the large
space structure.
Since the construction site is also close to the epicenter of the Nankai
Trough earthquake, it was necessary tosecure a margin for large-amplitude cyclic deformations under long duration
ground motions. Takenaka Corporation,
National Institute for Material Science(NIMS) and Awaji Materia have jointly
developed a bracing type damper with 10
times higher fatigue durability than ordinary steel damper, using excellent fatigue-resistant characteristics of Fe-MnSi-based alloy, and applied it for the firsttime.

Installation of fatigue-resistant damper

Outline of Structural Planning
100 m
4.8 m
~ 6.0 mBeambottomlevel
20 m
Reduction of verticalmotion by oil damper
Fatigue-resistant damper (16 pieces)

11 Steel Construction Today & Tomorrow April 2021

Truss column parts are
effectively used as MEP space

1FL

Achievement Awards

The Okura Tokyo

Prize winner: Taisei Corporation
The Okura Tokyo project is a rebuilding
plan for the former Hotel Okura Tokyo.
Two major propositions were imposedon the rebuilding plan: the complete reappearance of the former Okura lobby,
and the realization of a hotel and officewhere you can safely and securely pass
time.
Structural Plans
For the guest room floors located on theupper section of this high-rise building, a“braced tube structure frame” was adopted in which the mega braces to restrict
multi layers were arranged on the wall
position, a boundary between the guest
room corridor and the void, thereby enhancing the horizontal stiffness of theentire guest room floors. As a result, it
was possible to lessen the horizontal load
borne by the peripheral columns and to
make narrow the column sectional dimensions, which led to an improved lay-out of guest rooms and securement of afine view. Because all of the guest room
floors were consolidated by the use ofbraces, the inter-story drift angle became
small and damage to high-grade finishing members and fittings of the guest
room totaling about 370 was mitigated.
Because of the difference of column
allocation between the upper guest room
floors and the lower office floors, diagonal columns that can smoothly transfer
the column axial force were arranged at
the structure switchover floor. A 20-ton
cast steel joint was adopted for every diagonal column end joint section wherecolumns and beams gather three-dimensionally and in a complex manner so as
to secure a reasonable, continuous transfer of column axial force.
The accurate reappearance of the
Okura lobby was a proposition from theinitial stage of the rebuilding plan. Further, the column span and outer dimen-sion of 800 mm×800 mm were designated to follow to those of the original
design, and the outer dimension of structural columns was restricted to 600
mm×600 mm. In order to realize thesedemands, ultrahigh-strength concretefilled steel tube columns employing 780
N/mm2 high-strength steel product andFc150 concrete were adopted for columns subjected directly to the large column axial force of high-rise floors.
♦♦♦

Capitalizing on these advanced structural plans and diverse tests and examinations preceding practical construction,
we contributed towards the completionof a high-grade, highly seismic-resistantbuilding and the succession of the longestablished tradition of the former Hotel
Okura Tokyo through the reappearanceof the traditional Okura lobby.

Structural Overview

DamperdeviceOil damper
X : 32 units
Y : 48 units

Viscoelastic
friction damper
X : 18 units

ATMD

Hotel lower part

Steel column:
490 N/mm2

Guest rooms in 12 floors

The Okura Heritage Wing

Office in 18 floors

Structural switching floor

ATMD
Braced-tube structure
Outline of hotel floor

Guest rooms in 13 floors

The Okura Prestige Tower

Steel column:
490~590 N/mm2

External image

Huge caststeel joint

CFT column:
490~590 N/mm2+Fc60~80
Damper device
Oil damper
X : 144 units
Y : 78 units
Ultrahigh-strength
CFT columns
CFT column:
780 N/mm2+Fc150
Okura Lobby

Ultrahigh-strength concrete-filled steel tube column

Huge cast steel joint
BracketDiagonal
columnZ
YX

Huge cast steel joint
April 2021 Steel Construction Today & Tomorrow 12

-Outstanding Achievement Awards

DaiyaGate Ikebukuro

Prize winners: Nikken Sekkei Ltd. and Joint Venture of Obayashi Corporation and Seibu Construction Co., Ltd.
Seismic-isolation System on
Intermediate Floor
In the design of the office building “DaiyaGate Ikebukuro,” the project owner submitted a request to realize high seismic resistance that would allow for the building
to continue business operations even in theevent of an inland earthquake in the Tokyo metropolitan area as forecast to occur
in the near future. To meet this request, aseismic-isolated intermediate floor structure was adopted that also secures highstiffness for both upper and lower floors.
Specifically, a structural system wasadopted in which the seismic-isolated intermediate floor is sandwiched between upper and lower floors with highfloor stiffness (upper floors: brace framing; lower floor: mega framing employing diagonal columns that crosses over
the railway line). Also, a seismic-isolated intermediate floor system was adopted that could maximize the seismic energy absorption efficiency by means of theintensification of horizontal deformation
occurring during an earthquake to theseismic-isolated floor.
Further, because the foundation structure located at both sides under railway
lines cannot be linked to each other, re-dundant deformation capacity was secured for the framing to be able to resist
the inland earthquake motion, which also
led to the security of the entire building.
Minute Examinations for Exposed
BracesAiming for a building that would serve asa landmark in Ikebukuro, a downtown area of Tokyo, a structural type was chosenthat exposed the seismic-resistant braceoutward. Further its appearance was designed so that bolt joints could not beseen due to the transfer of the brace axial
force only by a web. In order to realize themaintenance-free application of exposed
braces, hot-dip galvanized steel members
were adopted. Thus, a building was completed in which the appearance design andstructural rationality are well fused.
Minute examinations were extended inevery process from detailed joint design
to the manufacture and quality control ofthe seismic-resistant braces exposed to theexterior. In particular, advance examinations were extensively made for full-scale
brace members: examination of full-scalemodel→test piece manufacture→hot-dip
galvanizing→performance confirmation
test. Every piece of knowledge obtained

Framing Elevation at Standard Floor

Full view of DaiyaGate Ikebukuro

Cross Section Plan

76 m

Office
space

100 m

18 m

10.8 m65 m

Peripheral
beam axial
force
System to transfer inertia force from office space via steel plate floor
13 Steel Construction Today & Tomorrow April 2021

Brace
axial
force

5m

Deck
24 m
11 m 8 m

Beamaxial force(couple offorces)Horizontal
force of steel
plate floor

Railway lines

Restaurant
Hall

TunnelParking lot

Impossible linkage offoundation structures(separated)

20 m

3.8 m

Seismicisolated
floor

10.5 m18 m

Officespace

47 m

14.4 m18 m

All seismic forces to be borne by outer framing braces;
maximization of office space by the use of slender (400×400 square)and long-span inner columns
Steel plate floor

from these examinations was shared
among construction companies, fabricators and those engaged in on-site workand applied in full to the construction tocomplete the DaiyaGate Ikebukuro withnot only high seismic resistance but finestructural aesthetics.

JSSC Commendations for Outstanding Achievements in 2020-Thesis Awards

Elasto-Plastic Analytical Program with
Generalized Plastic Hinge for Steel Square
Tube Column with Local Buckling

Prize winners: Kai Sakuma, Motohide Tada, Yurika Yasui and Seiji MukaideMotohide Tada

1982: Graduated from Graduate
School of Engineering,Osaka University
1982: Entered NIKKEN SEKKEI
LTD.
1989: Assistant Professor,
Osaka University
2007: Professor, Osaka University

Targeting square steel tube columns thatcause local buckling due to the application of axial force and biaxial bending,we have developed a program to analyze
the cyclic elasto-plastic behavior of columns by the use of the generalized plastic hinge method, an outline of which is
introduced below:

1.5

1.5 n

-0.4

-0.3

-0.2

0

-0.1

1

-1.5

-1

m

0

-0.5

0

0.5

1

-0.5

0

④

⑧

0.1

0.2

0.3

0.4

θ

0.5

⑩

⑦

⑥

1.5

1.5

⑤

⑨

-1
-1.5

(a) m−θ relation

-1

-1.5
1

0.5

m

n

n

1.5

-1.5

③

⑪-0.5

0.5

Inner yield surface
Outer yield surface
Lower limit surface

②

①1

1.5

-1.5

m

0.5

0
0.1

①
A

0.2

n=- 0.15

0.3

n=- 0.20

0.5
0.7

n=0.00(b) Stage ①(c) Stage ②

n1.5

n

Fig. 2 Update of Yield Surface
n

1.5

③ m

1

0.5

-1.5

-1

0

-0.5

0

0.5

1

④,⑤

⑥

m

B

m
1.5

-1

-1.5

m

n=- 0.05

0.6

0.7

②

m

n=- 0.10

0.4

θ
(rad)

-0.5

-0.3

-0.3

(d) Stage ③(e) Stages ④~⑥

n

n

-0.2
-0.1
1

0
0.1
0.2
0.3

θ
(rad)

m
1.5

0.5

0

-1

-0.5

⑦,⑩

⑧,⑨

m

⑪

m

B

0.4

0.5
n=0.0 → - 0.2
0.5

Updating Rule for Multiple Yield
Surfaces
Based on the knowledge thus obtained, it
was decided to specify an updating rule
for the yield surface of the generalized
plastic hinge model as in the following.
Fig. 3 (a) shows an example of m-θ relationships, and Fig. 3 (b~g) shows the
movement of the stress point on the corresponding m-n plane.

Fig. 3 Update of Yield Surface
Corresponding to m-θ Relation

Fig. 1 Lower Limit Surface

0

Reloading Behavior after Deterioration due to Local Buckling
The loading-deformation behavior ofcolumns after local buckling was analyzed by means of shell element-applied finite element analysis. As a result,it was found that the deterioration lower limit for the relationship between thedimensionless bending moment (m) andthe member end rotation angle (θ) canbe specified by the use of the lower limit
surface obtained by contracting the outer yield surface centering on the tensionside singular point as shown in Fig. 1.
The n in the figure shows the dimensionless axial force.
Further, it was found that the cyclic
behavior can be specified by contracting the yield surface centering on thetension-side singular point and then byslanting the base line on the n axis asshown in Fig. 2.

sition and the size of the yield surface iscontracted. On this occasion, the yieldsurface is settled to surely pass point B
in Fig. 3 (f).
In the prize-winning thesis, the behavior in which the space steel structurecompletely collapses due to an attack by
a huge earthquake was analyzed using
the generalized plastic hinge model.

After arrival at the maximum strength
at stage ②, the outer yield surface is contracted centering on the tension-side singular point and the base line on the naxis is slanted. After the outer yield surface contacts with the deterioration lower-limit surface at stage ④, m-θ point
reaches stage ⑤ by setting the tangential stiffness at 0 and fixing the yield surface. At stage ⑥, the stress point reaches
the yield surface at the m-axis negativeside to cause re-yielding after the reversal of θ. During the course from stage⑥ to stage ⑦ after re-yielding, the slanted base line is returned to the original po-(f) Stages ⑦~⑩(g) Stage ⑪

April 2021 Steel Construction Today & Tomorrow 14

-Thesis Awards

Mechanical Properties of Steels for
Bridge High Performance Structures
Subjected to Heating and Cooling
Processes Simulating Fire

Prize winners: Mikihito Hirohata, Daiki Teraguchi and Yasuo Kitane
Mikihito Hirohata

2008: Graduated from Doctoral
Course, Graduate Schoolof Engineering, Osaka
University
2008: Specially Appointed
Assistant Professor,
Joining and Welding Research Institute,
Osaka University
2011: Assistant Professor, Graduate School ofEngineering, Nagoya University
2015: Associate Professor, Graduate Schoolof Engineering, Nagoya University
2018: Associate Professor, Graduate Schoolof Engineering, Osaka University

Steel Bridges Exposed to FireIn the survey of damage conditions anddegradation of steel bridges subjected tofire, it is important to assume the maximum heating temperature of the bridge
members exposed to fire. It is reported
that, in the case of the heating of general rolled steel products to 600°C, theirmechanical properties after heating andcooling show no change. Accordingly, taking into account the safe-side allowance, the standard maximum heating temperature for which the surveyof changes of mechanical properties
is judged unnecessary is prescribed at

400°C for general rolled steel products.
High yield-point steel for bridge construction (SBHS: Steel for Bridge High
Performance Structures) was standardized in JIS in 2008. Data on the mechanical properties of SBHS after being subjected to heating and cooling has not yet
been prepared. Accordingly, in the casewhen SBHS with which high performance is imparted by means of thermomechanical control is subjected to thermal hysteresis due to fire, it is considered
important to make it clear how its mechanical properties will undergo change.

erties greatly changed, and there werecases in which the mechanical properties
did not satisfy the values specified in JIS.
Based on the above results, examinations were made on the standard maximum heating temperature to judge
whether or not a survey of changes inmechanical properties is required in cases when steel bridges employing SBHS400 and SBHS500 are subjected tofire, which led to a maximum heating
temperature likely to be applicable of
400°C for SBHS400 and SBHS500 aswith general rolled steel products.

Maximum Heating Temperaturefor SBHS
In this study, heating/cooling experiments (Fig. 1) and various kinds of material tests based on the assumption of fire
heating and extinguishing in steel bridges were conducted for two grades of SBHS400 and SBHS500. In the case of airor water cooling after heating to 600°C,
the mechanical properties nearly did notchange compared to those before air orwater cooling, as seen in Fig. 2. Under
the condition of air or water cooling after
heating to 900°C, the mechanical prop-

Fig. 1 Appearance of Heating
ExperimentFig. 2 Strengths of SBHS400 with Heating and Cooling
800

800

SBHS400

Air coolingTemperature (℃)
600
900

Water cooling

Water cooling

Without heating/cooling

Without heating/cooling

600

Range of JIS

Minimum standard of JIS
400

200

0

Furnace (900℃)

Fig. 3 Strengths of SBHS500 with Heating and CoolingStress σ (MPa)Stress σ (MPa)600

Air coolingTemperature (℃)
600
900

Test steels

SBHS500
Range of JIS

Minimum standard of JIS

400

200

Yield strength

15 Steel Construction Today & Tomorrow April 2021

Tensile strength0

Yield strength

Tensile strength-Thesis Awards

Plastic Deformation Capacity ofPre-assembled Type Built-up H-shaped
Beam by Submerged Arc Welding

Prize winners: Mototsugu Tabuchi, Tatsuya Nakano, Hayato Asada, Kohei Takatsuka, Tsuyoshi
Tanaka, Ryuichi Shimura, Takao Fukumoto, Kazuhiro Toyama, Kazuhiko Kamakura, Seiji
Fujisawa, Toshiomi Itatani, Yukihiro Shimano, Hideo Otsuka and Yasuo Ichinohe

Preface
In this study, in order to prevent premature brittle fractures occurring in builtup H-shaped (BH) beams produced bymeans of submerged arc welding (SAW),
we investigated the effect of the toughness of SAW metal on the plastic deformation capacity of BH beam connected with RHS column (Fig. 1). The study
consisted of the following three parts:
Part 1: Mechanical Properties of
the Fillet Weld Metal by One-pass
Submerged Arc Welding
The toughness of SAW metal is guaranteed in JIS Z 3183, for which multi-layer multi-pass welding is used as shown in
Fig. 2 (a). Meanwhile, SAW used for producing BH beams is one-pass fillet welding (Fig. 2 (b)), and accordingly, as shownin Fig. 3, the toughness of the SAW metalchanges depending on the kind of fluxes
applied, and further the toughness of onepass fillet welding (vE0) is lower than thatobtained from JIS testing methods.

Fig. 1 Detail of Beam-end Connection
SAW
A

Beam
ColumnA'(b) Around weld
access hole(a) Beam-to-column
connection

Fig. 2 Macro Photo of SAW Metal(a) Deposited metal in (b) Fillet weld of BH
JIS
beam

Fig. 3 Toughness of SAW Metal
8060
E0 (J)

1971: Graduated from Graduate
School, Kobe University
1995: Professor, Kobe University
2010: Professor Emeritus, Kobe
University
Professor, Otemae University
2018: Retired from Otemae University

Part 2: Full-scale Sub-assemblage
Tests
A total of 16 full-scale test specimens,
which were prepared by changing thebeam section to 3 kinds (tw/tf =25/36,
16/25, 9/16) and the toughness of theFillet weld
metal

40

Deposited
metal in JISv

Mototsugu Tabuchi

20

Fig. 4 Strain-concentrated Point
Strain-concentrated point0

LF LN MN HN

Fig. 6 Relationship between Plastic Deformation Capacity of
Beam-end Connection and Toughness of SAW Metal

20: Transformation to

NF (cyc)brittle fracture
within SAW metal: Transformation tobrittle fracture at
SAW bond: Transformation tobrittle fracture or
occurrence ofductile fracture inflange base metal

15(a) Occurrence of inferiorpenetrated section (A-A’)(a) In the case of low toughness

105(b) No occurrence of inferiorpenetrated section (A-A’)

Part 3: Relationship between
Plastic Deformation Capacity andToughness
Fig. 6 shows the relationship between
the fracture cycle (Nf) and Charpy absorbed energy of the SAW metal (vEtest).
As vEtest becomes larger, Nf becomes larger, which reveals that in cases when vEtest
is about 30 (J) or lower, it is impossible
to satisfy the plastic deformation capacity Nf≒5 required for the beam end of ahigh-rise building to possess.

JIS-specified
value

Fig. 5 Fracture Mode

Strain-concentrated point

SAW metals to 3 kinds, were tested under a constant cyclic loading (θ/θp=3).
The typical fracture mode of the beam
end is as follows: The strain-concentrated point is formed in the SAW metal as
shown in Fig. 4, and the ductile crack develops from that point to cause the fracture of the beam flange.
The fracture mode can be classified
depending on the toughness of the SAW
metals. In the case of low toughness (Fig.
5 (a)), the ductile cracking that occurs inthe strain-concentrated point transforms
to a brittle fracture within the SAW metal. Meanwhile, in the case of high toughness (Fig. 5 (b)), the ductile cracking develops into the beam flange base metal.
Further, the ductile cracking that occurs
in the inferior-penetrated weld tip does
not constitute a direct cause for fracture.

(b) In the case of high toughness0

No occurrence ofinferior-penetrated
sectionV Etest (J)
0

20

40

60

80

Plastic deformation
capacity required forthe beam end of ahigh-rise building topossess

April 2021 Steel Construction Today & Tomorrow 16

-Thesis Awards

A Series of Studies on Repairs to Lowrise Braced Structures after Disasters

Prize winners: Shotaro Nakada and Shoichi Kishiki
Shotaro Nakada

In this study, for turnbuckle braces, the relationship between the scaleof aftershocks and the response deformation/repair effect was investigatedby numerical analysis. And then, therepair method by means of turnbuckle retightening was established throughstructural experiments.

2017: Graduated from theFaculty of Engineering,
University of the Ryukyus
2019: Enrolled in a doctoral
course, School ofEnvironment and Society,
Tokyo Institute of Technology
2020: Research Fellowship for Young
Scientists (DC2), Japan Society for the
Promotion of Science

Study Results
At first, setting the peak ground velocity (PGV) as the parameter for seismic ground motion, examinations bymeans of seismic response analysis
were made of the following two items:
the scale of aftershocks and need or noneed for repair; and the effect of therepair including partial repair on deformation reduction. Fig. 1 shows therelationship between the scale of aftershocks and the braces repaired for reducing deformation. The vertical axis
in the figure indicates the ratio of therepaired brace to all braces, and the

Study Purposes
Because gymnasiums are used as emergency public shelters in the event of a disaster, the securement of its seismic performance is an important task for disasterprevention. Meanwhile, even when braces avoid its serious damage such as fractures of joints, damage such as residual
deflection due to plastic deformation isobserved, and thus many examples havebeen reported in which gymnasiums employing such the damaged structure havenot been applied for emergency public
shelters.

Fig. 1 Relationship between the Scale of Aftershock and the
Repair that Can Suppress Deformation
1.0

Repaired braces
All braces

0.5

PGV of aftershock

0.0
0.0

PGV of mainshock
0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

horizontal axis the ratio of the PGV ofaftershocks to the PGV of mainshocks.
The solid line in the figure shows theupper-limit value obtained based on all
analysis results.
It was found from the analysis results that in cases when most of aftershocks are roughly 20% or lower thanthe mainshock in terms of scale, the response deformation of aftershock does
not increase compared to that of themainshock and thus urgent repair is
not required. Further, it was found thatwhen the scale of aftershocks is morethan 20% that of mainshocks, prompt
repair is required and that when thescale of aftershocks is about 54% orhigher than that of the mainshock, allturnbuckles should be retighten.
Next, a structural experiment was
carried out to establish repair methodby retightening of turnbuckles (Fig. 2).
For the hysteresis curve after retightening (solid line in Fig. 3), slip behavior
due to damage was eliminated and thehysteresis curve after retightening almost exceeded that at the stage of damage loading (broken line in Fig. 3). It
was confirmed that the repair methodby means of turnbuckle retightening isuseful.
In addition, the retightening workability was investigated, through which
it was experimentally made clear thatdamage of the screw section due to cyclic plastic deformation was not caused
and stabilized retightening workability
was thus obtained.

1.0

Fig. 3 Effect of Turnbuckle Retightening on
Repair70
60

Fig. 2 Setup of Structural Experiment
Oil jack

Horizontal roller jig
Specimen

DamageRepairNx[kN]

DamageRepair50
40

Load cell

30
20
10
-1.0

17 Steel Construction Today & Tomorrow April 2021

-0.5

0.0

ε[%]
0.5

1.0

JSSC Events

The First IABSE Online Conference 2020

by Shunichi Nakamura, Tokai University, Vice President of IABSE
The whole world has suffered the
COVID-19 pandemic, which has affected
almost everybody. It has changed the
IABSE events planned for the year 2020.
To cope with such circumstances, IABSE(International Association for Bridge andStructural Engineering) organized theFirst IABSE Online Conference 2020.
The conference was held on September
2-3 on Zoom. The Japanese Groupof IABSE organized this conferencewith the Chinese and Korean Groups.
Prof. Y. Ge (President of IABSE) madea welcome address at the opening
session. The Japanese Society of Steel
Construction serves as a secretariat ofJapanese group of IABSE.

on “Field Investigation and Restorationof Damaged Bridges in 2016 Kumamoto
Earthquake” and Prof. K. Nishijima(Kyoto University) presented “Disasterof buildings caused by Typhoons Jebi
and Faxai.” For Topic-2, Prof. P-J Chun
(The University of Tokyo) presented“Application of AI and data platform
to infrastructure maintenance and its
future prospects.” For Topic-3, Dr. H.
Kanaji (Hansin Expressway) presented“Conceptual and Schematic Design ofa Multi-span Cable-stayed Bridge inKobe.” For Topic-4, Prof. T. Nagayama(The University of Tokyo) presented“Monitoring taking advantage of andmaterializing digital twins.”

Facing the New Age!
The conference main theme was ‘Facing
the New Age!-How do structural
engineers tackle the COVID-19 era?,’which is the urgent and serious matterthe structural engineers must consider. In
the keynote sessions four distinguishedexperts presented their views on thismain theme. From Japan, Prof. Koichi
Kato (The University of Tokyo,
Architectural Historian) presented“Construction in the History of Social
Change-Learning from Epidemic in
Late Medieval Europe.” He reviewed
what happened to the construction
activities in the Black Death Period anddiscussed the matter of construction after
COVID-19 society from the long-term
viewpoint. Other keynote speakers were
Mr. Klaus Ostenfeld (Former Presidentof IABSE), Dr. Liming Yuan (CentralSouth Architectural Design Institute),
and Prof. Young Sang Kwon (Seoul
National University).
The conference adopted four subtopics: T1: Recent extreme events on
infrastructures, T2: AI-based monitoringand maintenance of infrastructures,
T3: Development of long-span cable
supported bridges, and T4: Digital
inclusion in structural engineering. A
total of 16 international experts presented
the latest technologies and research at
the Topic Sessions.
Four experts from the Japanese Groupmade presentations. For Topic-1, Prof. S.
Fujikura (Utsunomiya University) talked

Successful Online Conference
The whole conference was operated in
the zoom webinar mode. Presentations
were all pre-recorded. At the sessions,the chair introduced the recorded
presentations and the Q&A sessions
were conducted live. The audience sent
the questions to the Panel (the session
chairs and the presenters) using the
Q&A function. The presenters answered
aurally and discussions were conducted

Prof. Y. Ge, President of
IABSE

between the presenters and the audience.
Questions came from not only China,
Korea and Japan but also from Europe,
America, India, Oceania and so on.
The Q&A sessions were very active
and lively. The whole procedures wentsmoothly and efficiently.
The recent structures were introduced
at lunch time. From Japan, Largerehabilitation project of the Metropolitan
Expressway, Mukogawa Bridge, Tokyo
National Sports Facilities, Tainan Art
Museum were shown.
We adopted a new style of international conference, remote and online system. This was a real challenge. A total of
330 people registered in the conference
and, in addition, the Chinese Group of
IABSE had 219 local participants. The
maximum number of live participants
was over 400, which was over our expectation. This online conference is a success and would be a promising style forthe future IABSE activities.

Q&A with Prof. K. Kato (Keynote Speaker)
with Prof. S. Nakamura (Chair)

Topic Session 1: Prof. S. Fujikura, Prof. K. Nishijima (Invited Speakers)
with Prof. H. Katsuchi (Chair)

Topic Session 2, 3, 4: Prof. S. Chun, Dr. H. Kanaji and Prof. T. Nagayama (Invited Speakers)

April 2021 Steel Construction Today & Tomorrow 18

Program to Foster Steel Construction
Engineers
The Japanese Society of Steel Construction has carried out a “Program to Foster Steel Construction Engineers” since2009. Its main aim is to foster young engineers with a career of several years after joining companies and for the succession of steel construction technologies.
In addition to lectures delivered bylearned persons and those working in thepractical steel construction field, study
courses and site tours are also held.
The number of participants to the program has surpassed 26,000 over the past
12 years. This fostering program has
gained a high reputation from JSSC member companies as a good opportunity forbackbone engineers to obtain knowledge
useful in taking a steady leap forward.
In 2020, two study courses for thepractice of high-strength bolt joining,two study courses for the practice of
welding, and three site tours each to civil engineering project, building construction and steel-frame fabricator.
Among these programs was an on-site
tour to the “Seismic Retrofitting of the Kamihirai Flood Gate” that appeared in issue
No. 59 (April 2020) of Steel Construction
Today & Tomorrow. In this regard, JSSC
received comments from participants suchas-“We were able to understand that, because the gate is equipped with an opening/closing system and other facilities peculiar to the flood gate, it is necessary to acquire not only knowledge about steel-frame
fabrication and erection involved in bridge
construction but knowledge about electricalsystems” and “Because the gate is an infrastructure facility needed in the event of a disaster and in case of emergency as well, thedoubled and redoubled failsafe functions
are provided with an opening/closing system, and thus we were deeply impressed bya high technical level of the gate.”

Site tour to Kamihirai Flood Gate

JSSC International Committee

Message from Chairman

by Hiroshi Katsuchi, Chairman, International Committee(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 spread ofsteel construction and improving associated technologies, and at the same timeit has extended cooperation to related
overseas organizations. Aimed at spreading Japan’s steel construction technologies and developing overseas markets,
the JSSC’s International Committee was
responsible for issue No. 61.

Issue No. 61 features “Natural Disasters: Restoration and Countermeasures,”in which four examples are introducedthe short-term restoration of Kansai International Airport Access Bridge froma tanker collision due to typhoon winds,
inland earthquake countermeasures adopted for buildings, countermeasuresagainst natural disasters on railways andemergency bridges for temporary use forflown-out bridges.
In addition, this issue introduces the
JSSC commendations for outstandingachievements in 2020 in the field of steel
construction and thesis. As a special article on stainless steel, the Fukuoka Law-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

yer’s Hall is introduced that applies finely-polished stainless steel for exterior
and interior finishing.
As for JSSC activities, the First IABSE Online Conference 2020 organizedjointly by Japanese, Chinese and Koreangroups is introduced. Diverse programs
to foster steel construction engineers,
carried out in 2020, are reported.
We hope for a fast recovery from COVID-19 and the revisiting of the security and development of society. We would
also like for everyone to understand theactivities of JSSC and at the same time
we would like to hear your opinions at
any time.

© 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): Koji Oki
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: 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.