No. 64 April 2022

STEEL CONSTRUCTIONTODAY & TOMORROW

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

Special Issue

Japanese Society of
Steel Construction
JSSC Commendations for Outstanding Achievements in 2021

• Outstanding Achievement
Awards1 ACADEMIC-ARK of
Otemon Gakuin

2 SHIBUYA SCRAMBLE

SQUARE The First Phase(East Tower)

3 “Voronoi Partition”

Space Design of Sanei
Construction Steel Structure
Division New Office

4 Yokohama City Hall
5 Shibuya Station on theTokyo Metro Ginza Line• Thesis Awards

6 Local Deformation Behavior of SHS in Beam-to-Column
Connection with Exterior-diaphragm Assembled
by High-strength Bolts

7 Improvement of Fatigue Durability in Welded Gusset Joints
by Carbon Fiber Sheets Using VaRTM Technique

8 Influence of Bolt Shape and Dimensions on Mechanical Propertyof 1700 MPa-Class Ultra-High Strength Bolt

Feature Article: R&D on Advanced Mechanical Fastening Technology

9 Examination of High-strength Bolt Fastening by OS Method
Special Article: Stainless Steel

16 SUS Lining Applied in the Jacket-type Pier at Tokyo International
Cruise Terminal

JSSC Events

18 The 7th China-Japan-Korea Tall Building Forum in 2021
JSSC International Committee

19 Message from the Chairman
Published Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel ConstructionJSSC Commendations for Outstanding Achievements in 2021-Outstanding

ACADEMIC-ARK of Otemon Gakuin

Prize winners: Mitsubishi Jisho Sekkei Inc. and Takenaka Corporation
Equilateral Triangle Structural
Plane
The ACADEMIC-ARK is the projectplanned for building a new school campus of Otemon Gakuin on a vast plant
track site development area located in
the northern part of Osaka Prefecture. In
the age of the internet society where students can learn without attending school,
we examined the design of a school campus where human activities can be felt
because it is a real space. Specifically,
we proposed a school building featuring an equilateral triangle plane where
the library, hall and other bustling places
are surrounded by the classroom, direct
facing with the windows of neighboringhouses is reduced and campus plaza canbe opened to the local community.
Certain restrictions were imposedon the project-a tight schedule of 29
months from the start of design to the
opening of the new campus and the loca-

tion of the project site at a buried culturalproperty survey area. In order to reduce
the survey period and secure a reliable
schedule, we proposed a sharp reductionof foundation area (building groundingarea) by widely overhanging the building corner section and providing a firstfloor center area with column-free space.
Overhanging Construction
A major seismic-resistant element provided was the seismic-resistant wall withthicknesses of 1,200 to 1,300 mm, andfour walls were arranged to each side.
The huge-scale overhanging sections
at three corners with an overhanging extension of about 37 m were formed using triangle-shaped framings composedof four layers of overhanging structures,and the triangle framings were structured by the minimum use of structuralmembers by supporting the intermediate overhanging structure with suspen-sion members.
On the first floor, a large hall was arranged in which entrance ceremonies canbe held, and the lower section of the library on the hall was made column-free.
The library was supported with diagonal columns installed as they sandwich
from the top to the bottom, which led tothe creation of not only the column-free
first-floor plaza but also an open rooftop
garden.
The peripheral section of the building
is covered with stainless steel cast panelswith a motif of “cherry blossoms,” theschool emblem of Otemon Gakuin. An
image of the building covered only withcherry blossom petals is expressed by resisting the wind pressure with the castpanel itself and minimizing the use of
supporting frames, and at the same timea characteristic façade has been realized
in which its appearance changes depending on the time and angle.

Framing Elevation of Overhanging Structure
Diagonal column(□-700×40)
Steel beam(depth: 1100)

Suspension member(□-200×30)
Column installed
on intermediate
frame (□-400)

Diagonal column(□-900×40)
Triangle-shaped overhanging structure

Bridge beam tosupport the truss(H-1100)

Diagonal column tosupport the truss(□-650×40)

Column-free first-floor plaza
1 Steel Construction Today & Tomorrow April 2022

Suspension column installedfrom the bearing wall top(H-500×500)

Boat-shaped truss

Achievement Awards

SHIBUYA SCRAMBLE SQUARE The First
Phase (East Tower)

Prize winners: Shibuya Station District Development Project Consortium and Shibuya Station
District East Tower New Construction Consortium
Outline of Building PlanA redevelopment project is underway around
Shibuya Station located in the downtown area of Tokyo. The redevelopment scale is said
to be once every 100 years, and the Shibuya
Scramble Square is located in the center ofthe project. The low-rise floors are composed of the commercial facilities, the medium-rise floors the co-creation facilities thatenhance international competitiveness, andthe high-rise floors the office and other facilities. On the rooftop with a height of 230 m,
an observation facility was provided that cancommand a view of the scramble crossing.
Outline of Structural Plan
A seismic response-control structure wasadopted aiming at reducing the seismic
response in the event of an earthquake.

While there are some deviations in termsof framing arrangement due to the Shibuya
River flowing through the site and the existence of low-rise urban core, the horizontal
stiffness and strength were secured by arranging buckling-restrained braces mainly
to the core periphery from lower to upper
floors in a well-balanced manner, and at
the same time, damage to the main framing
was suppressed by adding damping performance by the use of oil dampers.
Because the optimum column span andposition differ at the low-rise or high-risefloors depending on their respective applications, the truss was installed at the 18th-floor
machine room at the boundary floor in order not only to switch over the column andtreat the horizontal component force but also
to correct the bending of the entire framing.

Photo: SHIBUYA SCRAMBLE SQUARE

On the low-rise commercial facility
floors where the floor height and the rateof the occurrence of shear deformation are
high, the shear link-type oil damper was arranged to secure the damping performance.
On the high-rise office floors where the rateof the occurrence of flexural deformation
is high, in order to make use of this large
flexural deformation as an effective deformation, both the buckling-restrained brace
and the axial brace-type oil damper werearranged in the core framing, which led tothe effective absorption of seismic energy.
On the observation facility, the core wasreinforced using the brace and the freedom
in planning the peripheral observation corridor was enhanced by overhanging a cantilever truss by one layer to the periphery,
which led to the securement of wide view.

Framing Plan at Office Floor
18.3 m 19.8 m18.3 m

10.8 m10.8 m10.8 mApprox. 60 m

10.8 m
7.2 m10.0 mApprox. 56 m

Conceptual Drawing of Building Structure
Observation
facility

Steel structure

OfficeFull view of SHIBUYA SCRAMBLE SQUAREApprox. 230 m

Equipment/machine room
Co-creation facility

Steel structure
Concrete-filledsteel tube column

Commercial
facility
Urban core
1FL
Steel-reinforced
concrete composite
structure
Response-control system installed at the office floor

Approx. 40 m

Approx. 60 m
April 2022 Steel Construction Today & Tomorrow 2

-Outstanding Achievement Awards“Voronoi Partition” Space Design ofSanei Construction Steel Structure
Division New OfficePrize winners: Sanei Construction and Takenaka Corporation
The New Office of the Sanei Construction Steel Structure Division is asteel-structure office building plannedin Osaka. Steel frames used for theconstruction of the building were
manufactured by Sanei Construction,
the project owner, as a fabricator at its
neighboring fabrication plant. In order to fully appeal the advanced steelframe fabrication technology possessed by Sanei Construction, we took
on the challenge of a structural designthat demonstrates dynamical steel
framing.
Creation of Office Space byMeans of Voronoi Partition
In the partition of the construction
volume, the “Voronoi partition” geometry was adopted, which brought
about a three-dimensional multi-faceted relationship between rooms andaccelerated the mutual exchange of
employees. In addition, the dynamic complex framing manufactured bymeans of the Voronoi partition led to

Full view of the new office building

appealing to the advanced steel-frame
manufacturing technology of the project owner.
The main framing was composed
entirely of steel tubes with a diameterof 318.5 mm. Pin joints were adopted for the steel tube column-to-beamconnection, and a structural plan wasformulated so that the stress occurringin the event of an earthquake does not
become excessive for the framing. For
the bolt joints used for the pin connection, the structural design was made sothat the continuity of the framing employing steel tubes was not impaired.
Voronoi Steel Plate Walls
Steel plate walls were adopted as partof the seismic-resistant elements thatbear 70% of seismic force. The twodimensional “Voronoi partition” wasincorporated into the design of theconfiguration of buckling-stiffening
ribs, which led to the expression of asteel plate that gives a strong impact
on visitors. Both the “Voronoi parti-

Frame joint and steel plate slabtion” steel plate wall and the buckling-stiffening rib are composed of
PL-9 steel plates.
Steel Plate Slabs
Steel plate slabs were adopted as the
structural slabs, which facilitated the
reduction of the visible thickness offloor members and a lightweight architectural expression. When looking up the steel plate slab, the lower
plate of the plate slab appears as an
aspect surface to more strikingly demonstrate the dynamical structure realized by the maximum use of steel.
The joint detail was minutely
planned from the start of design, andas a result it was possible to finely andprecisely finish the steel plate slab.

“Voronoi partition” steel plate wall

Structural Frame Drawing

Voronoi framingΦ318.5Voronoi seismic-resistant wall

3 Steel Construction Today & Tomorrow April 2022

Steel plate slab

Cross hatch brace

Steel-frame beam+Steel pile cap

-Outstanding Achievement Awards

Yokohama City Hall

Prize winner: Joint venture of Takenaka Corporation and Nishimatsu Construction Co., Ltd.
Yokohama City Hall is the government
office building, the eighth building of theCity of Yokohama. Plans called for theconstruction of a new government officebuilding that fulfills the core role in crises management, serves as an open venue for making full use of affluent citizen
power and allows applications over thelong term. The new government office isa steel-structure high-rise building withtwo basements and 32 stories aboveground, and a height of 155 m.
High Seismic Safety andAdvanced Steel Construction
Technologies
A mid-story isolated structure in which
the base-isolation layer was arranged under the 3rd-story floor was adopted, andat the same time response-control devices were arranged to the upper and lower structures of the base-isolation layer to further enhance the mitigation of
response acceleration during an earthquake. As a result, the “Kind I seismic
safety*+Suppression of building tremor”
were realized in this new government office building to securely meet the needfor the seismic safety requested from theCity of Yokohama.
In the construction of the new building, maximum demonstration of not only
the strength and toughness of steel products but freedom in shaping was pursued
capitalizing on both the development ofelementary technologies accompaniedby structural tests and new structuralplanning ideas-specifically, the development of the pile head joining method by CFT adopted to enhance the safety of foundation framing, the realizationof atrium space that is moveable straddling the base-isolation layer employing ball joints composed of cast steel andspecial high-strength brass-plated steel, arational framing plan by the use of CFT
columns employing high-strength steel
product (590 N/mm2 TMCP Box Column Press). On account of these technological achievements, the basic ideas
for the new building pursued by the Cityof Yokohama-high seismic resistance,
creation of attractive space and ease ofmaintenance-have surely been embodied in the new building.
Throughout construction, challenging
efforts were positively extended aimed
at securing quality, improving safety andproductivity and reducing CO2 emissions
through the reduction of the construction
period by means of the top-down construction method and steel-frame construction of basement floors, the securement of welding quality in the useof high-strength steel products and themitigation of CO2 emissions by the useof ECM** concrete, which also made astrong contribution towards the realization of a sustainable society.
In the equipment plan, diverse kindsof eco-friendly technologies were introduced to attain the construction of the

ZEBReady*** government office building.
*Securement of safety of buildings against
seismic force increased by the importancefactor (seismic force 1.5 times that of common
buildings)**ECM: Energy• CO 2 Minimum***ZEB Ready (Zero Energy Building Ready):
A building defined as a 50% energy-savingbuilding compared to a reference standard
building in Japan
Photo: Shigeo Ogawa

Appearance of Yokohama City Hall
Photo: Shigeo Ogawa

Perspective View of Structural Framing
Government office building

Braced frame
structure employing
square steel tube
seismic-resistantbrace
Council building

Adoption ofpile head joining
method by CFT to
the pile that serves as
the short-length pile forthe inclined support layer

Hybrid base-isolation
structure consisting of
mid-story base isolation
structure under 3rd-story
floor and response-control
deviceAtriumRealization of atriumby the use of caststeel ball joint andsuspension framing
for exterior cladding

Inner view of atrium

Conceptual Drawing for Atrium
Edge 3D truss(Truss depth 2.2 m)
Main building

Wind-resistant truss(Truss depth 2.0~2.2 m)
Roof truss(Truss depth 2.2 m)

16 m
Vertical
expansion
joint 880 mm
Tie-rod 25 Φ
Small-diameter steel tube column(318.5~355.6 Φ)(Column head/column base: ball joint)

4.5 m
Vertical truss(Channel steel, circular steel tube)
Lower framing
Horizontal expansion joint

April 2022 Steel Construction Today & Tomorrow 4

-Outstanding Achievement Awards

Shibuya Station on the Tokyo Metro
Ginza Line

Prize winners: Tokyo Metro Co., Ltd.; Metro Development Co., Ltd.; Naito Architect & Associates;
Tokyu Architects & Engineers, Inc.; Pacific Consultants Co., Ltd.; KAP; Joint Ventureof Tokyu Construction Co., Ltd., Shimizu Corporation and Kajima Corporation; Tomoe
Corporation; Miyaji Engineering Co., Ltd.; and FaB-Tec Japan Corporation
Construction of New Shibuya
StationShibuya Station on the Tokyo Metro Ginza Line is a link of the Land Rezoning Project of the Shibuya Station
Blocks, and is a new station building relocated from the former station building.
The former Shibuya Station on the GinzaLine posed some problems involvedin ongoing superannuation and building conditions. To cope with this situation, the former station building locatedin a department store was relocated eastward by 130 m, and a new station building was constructed on an elevated track
beam spanning Meijidori Avenue.
While securing the regular service ofthe subway line, the railway track beam
was rebuilt in ways that substantially reduced the number of the piers used forthe former elevated railway bridge, andthen the new station building was constructed on the new railway track beam.
The new station is an island-type platform serving two tracks, and the platform width was broadened to up to 12 m.
Full attention was paid to securing barrier-free transport, and the Skyway (pedestrian deck), a pedestrian network thatconnects the east and west sides around
Shibuya Station, was installed on theroof of the new station building.
Advanced Building Technologies
and Members
The entire station building is composedof an arch-shaped large space, and acharacteristic M-shaped configuration
was adopted that conforms with the dynamical performance of the building on
which the Skyway is installed. The station building has a structure in which Mshaped steel arch framings with box section are arranged at a span of 2.5 m, andits configuration continuously changes due to structural conditions such as
railway gradient, Skyway gradient andstructural clearances imposed on therailway construction. The track beam is
a 2-span half through-type steel slab/4
main box girder structure having a span
5 Steel Construction Today & Tomorrow April 2022

length of 55 m and is supported with reverse oval cone-shaped RC piers.
Because the building was locatedover Meijidori Avenue and thus heavy
construction machinery installed on the
ground could not be used, a sliding construction method was adopted-specifically, the temporary bent was installedover the road, on which the heavy machinery was placed, further the bent for
use for assembling arch framings was installed on the track, and the assembled
blocks including those for roof finishingwere moved to the prescribed erection
positions one after another.
The new Shibuya Station is a steelstructure station building that was completed by the integrated use of civil engineering and building structures andhas no precedent. To that end, the project required the extensive application ofadvanced technologies that not only secured regular railway service but also
hurdled the difficult conditions involvedin the promotion of the project in the
downtown area of Tokyo.

M-shaped arch steel framings arranged in the platform

Newly-completed Shibuya Station on theTokyo Metro Ginza LineNighttime construction of new station building

JSSC Commendations for Outstanding Achievements in 2021-Thesis Awards

Local Deformation Behavior of SHS in
Beam-to-Column Connection with Exteriordiaphragm Assembled by High-strength Bolts

Prize winners: Yugo Sato, Megumi Asanuma, Yuji Koetaka, Shintaro Matsuo and Tadayoshi Okada
Yugo Sato2007: Graduated from the
Graduate School ofEngineering, Utsunomiya
University
2007: Entered Nippon Steel &Sumikin Metal Products
Co., Ltd. (currently Nippon
Steel Metal Products Co.,Ltd.)

Background of the Study
The target of this study is the joining method
for beam-to-column connections employing
square hollow section (SHS) column and H
beam. In these connections, the flanges ofthe outer diaphragm are joined to each other by the use of high-strength bolt, and the
SHS column and the outer diaphragm arejoined by the use of the compressive force
that works between these two members due
to bolt joining. Then, the beams are connected with the webs of exterior diaphragm
members by means of high-strength bolt
friction joining (refer to Fig. 1).
Because the beam is not directly connected with the column, in the event of anearthquake, stress is transferred using thecompressive force occurring from the exterior diaphragm to the column. In the separately-conducted cyclic loading test for
cruciform frame, the column caused local
plastic deformation due to this compression
force, showing slip-type hysteretic behavior.
In this study, the experiment and analysis
were conducted to confirm the local deforFig. 1 Outline of Connection

mation behavior of the column and to establish the method for evaluating the strengthof the column in which the local plastic deformation occurs (local plastic strength).
Study Methods
Fig. 2 shows the setup of the experiment.
In the experiment, the basic local deformation behavior was confirmed setting
the side constraint and the shear span ratio as a parameter. In the parametric analysis, the local deformation behavior was
examined in detail using the width-tothickness ratio, shear span ratio and axial
force ratio as a parameter.
Study Results
The analyzed local plastic strength ALPpshown in Fig. 3 converged to a constantvalue when the shear span ratio was low
and gradually approached the calculated
full plastic flexural strength CBPp when theFig. 2 Setup of Experiment
Loading jig

Side constraint

ColumnMonotonic
Top view loading

Elevation viewFig. 3 Analysis Result andCalculation Result

FlangeColumnWeb
Exterior-diaphragm member

Pp

CL

CB

CL

1800

900
Beam

600

Friction
joint

300
0
0.0

Pp

(eq1)

Pp

Full plastic flexuralstrength
Analysis Calculation(CBPp)

1200

Cross-section viewFig. 4 Collapse Mechanism

Pp0

CL

Load (kN)
1500

Tensilejoint

shear span ratio was high. Taking into account the stress condition at ALPp when theshear-span ratio was low, the mechanismof the collapse due to local deformation
was assumed as shown in Fig. 4. In the figure, the center of plate thickness is modelled, and the range of 1/4 the section of
the column and 1/2 of the longitudinal direction is shown. The local plastic strength
CLPp0 when the shear span ratio was low,
calculated from the collapse mechanism,is shown in Fig. 3, and this calculated value corresponded well to ALPp.
Next the calculated local plastic
strength CLPp was settled from the equationof reciprocal action between CLPp0 and CBPp(eq1). Fig. 3 shows CLPp. The calculated local plastic strength CLPp corresponded wellwith the analyzed local plastic strength
ALPp. Further, the calculated local plastic
strength CLPp corresponded well with thevalue obtained in the experiment.

CL

Pp0

δ
Loading zone

Yield line
(continuous line)

Calculation (CLPp) Analysis (ALPp)
Local plastic strength
1.0

2.0

3.0
4.0
5.0
Shear span ratio
April 2022 Steel Construction Today & Tomorrow 6

-Thesis Awards

Improvement of Fatigue Durability in
Welded Gusset Joints by Carbon Fiber
Sheets Using VaRTM Technique

Prize winners: Visal Thay, Takumi Ozawa, Chang Tan, Hitoshi Nakamura and Takahiro Matsui

Specimens and Test Condition
The target specimens, non-strengthening
and strengthening specimens using VaRTM technique, of welded gusset plates
were fabricated and subjected to static load and cyclic load. Fig. 2 shows the
specimen preparation by externally bonded CF sheets using VaRTM technique. The
Fig. 1 Schematic View of VaRTM TechniqueDistribution media
Bagging film
Resin

Reinforcement (FRP)
Joint reinforcement
Sealant tape

Vent

Steel member

Fig. 2 Specimen Preparation
Inject

Vent

InjectBagging film Gusset plate Sealant tape(a) Specimen during strengthening process
by VaRTM technique

Evaluation of Fatigue Durability
Fig. 4 shows the S-N curve of the relationshipbetween the nominal stress range Δσsn and thenumber of cycles from the start of the test to
failure of specimen Nf from fatigue tests. In
the nominal stress range of 150 MPa, the prolongation of fatigue life reached the fatigue
limit (10 million cycles), while in the nominal stress range of 180 MPa, the fatigue life
Fig. 3 Reduction of Stress
Concentration400

ξ0:The.: 0.662
Stress at weld toe
Ana.: 0.665

300
200
100
0

Base plate Gusset plate
CFRP(b) Specimen after strengthening by VaRTM technique
7 Steel Construction Today & Tomorrow April 2022

0

HSS:
Ana.: 0.747
Exp.: 0.712

Non-strengthening (ana.)
Non-strengthening HSS (ana.)
Non-strengthening HSS (exp.)
Strengthening (ana.)
Strengthening HSS (ana.)
Strengthening HSS (exp.)

0.4t

1.0t

1 2 3 4 5 6 7 8 9 10Distance from weld toe in longitudinal
direction (mm)Summary
The result shows that the prolongation of
fatigue lives based on the stress reduction
factor ξ0 can be quantitatively evaluated and verified. Therefore, the strengthening by externally bonded CF sheets using VaRTM technique can be determinedby the stress reduction factor. It confirmedthat the proposed method is also effective
in delaying the lives of crack growth of Np.
Fig. 4 Fatigue Durability of Nominal
Stress Range Δσsn and Number
of Cycles Nf
JSSC_ F
200
180
160
140

Nominal stress range Δσsn (MPa)Introduction
This paper deals with the reduction of stressconcentration and fatigue durability of typicalwelded gusset joints in steel bridges strengthened by externally bonded carbon fiber (CF)sheets. As a composite molding method, Vacuum-assisted Resin Transfer Molding (VaRTM) technique has been newly proposed andcan be used to apply multiple CF sheets on
cracked steel structures as shown in Fig. 1.

Reduction of Stress Concentration
The reduction of stress concentration at theweld toe was analytically and experimentallyinvestigated. The 3D finite element analysis
model was simulated from a number of image data taken from the actual experimental
specimens by a digital camera. In evaluating
the reduction of stress concentration, hot-spot
stress (HSS) approach with 0.4t-1.0t method(t: steel plate thickness) was adopted.
Fig. 3 shows the comparison of the reduction of stress concentration between theoretical, analytical, and experimental results. The stress reduction factor of HSS
between non-strengthening and strengthening specimens from the analytical and experimental results are close to each other.
Moreover, the stress reduction at weld toe
between non-strengthening and strengthening specimens obtained from the analyticaland theoretical results are almost the same.

increased approximately 37 times, and all areover the JSSC-A grade.
Fig. 5 shows the S-N curve of the relationship between the converted nominal
stress range ξ0Δσsn and the number of cycles
from initiation of crack to failure of specimen Np from fatigue tests. The converted
nominal stress range of strengthening specimen (stress range at 120 MPa) can be plottedalong with the non-strengthening specimen.

E

D

C

B

A

37 times

120
100
90
80
70
60
50

Δσsn = 5480.4 Nf −0.285
R = 0.94

Non−strengthening (GPN)
Strengthening (GPC)
Regression line GPN
10

5

6

10
10
Number of cycles Nf (cycles)

7

Fig. 5 Fatigue Durability of Converted
Nominal Stress Range ξoΔσsn
and Number of Cycles Np
200
180
160
140

Converted nominal stress range
ξoΔσsn (MPa)2020: Graduated from Doctoral
Course of Graduate
School of Urban Environmental Sciences, Tokyo
Metropolitan University
2020: Postdoctoral Researcher,
Graduate School of Urban Environmental
Sciences, Tokyo Metropolitan University
2020: Project Assistant Professor, Graduate
School of Urban Environmental
Sciences, Tokyo Metropolitan University
2021: Assistant Professor, School of Regional
Design, Utsunomiya University

strengthening specimens were preparedwith 23 layers of CF sheets (high-strengthtype) at each side, equivalent to the stress
reduction factor of approximately 2/3(ξ0=0.662). The stress reduction factor is
the ratio of the tensile rigidity of CFRP tothat of steel plate.

Stress (MPa)Visal Thay

−0.166ξoΔσsn =1110.5 Np
R = 0.82

120

100
90
80
70
60
50
104

Non−strengthening (GPN)
Strengthening (GPC)
Regression line GPN+GPC
105
106
107
Number of cycles Np (cycles)

-Thesis Awards

Influence of Bolt Shape and Dimensions
on Mechanical Property of 1700 MPaClass Ultra-High Strength Bolt

Notch tensile strength (MPa)

Prototype steel:Fe-0.5C-2Si-1Cr-1Mo(mass%)(TS=1815 MPa)

H
7/8H

1

√3/3H

2

3

1/2H

R=1/3H√3/3H

R=1/6H

P

0
0

1/4H

P

500

√3/3H

H
7/8H

√3/3H

Fig. 1 Relationship between Notch
Tensile Strength and Stress
Concentration Factor

Te n s ile s tr e s s ( M P a )Prize winners: Yuuji Kimura, Hiroshi Masuda, Takashi Yamaguchi, Eiji Nagasaki,
Hitoshi Moriyama and Kaneaki Tsuzaki
1700 MPa-class shank preceding yield bolt. Here, the shape of tension control
type bolt having a waisted shank por- bolts, i.e., torshear bolts (JSS Ⅱ 09Yuuji Kimuration
and new threads.
2015), whose head was easier to cold
1993: Graduated from Graduate
form than hexagonal bolts, was adSchool of Engineering,
Kyushu University
1700 MPa-Class Shank
opted as the basic bolt shape. Second,
1993: Associate researcher,Preceding Yield Type Bolt
the optimum conditions for the comKyushu University
First,
prototypelow-alloy
steel,
which
bination of the waisted shank and the
1999: Researcher, National
was developed as a material for 1700 thread form were found through tensile
Research Institute for Metals
2001: Senior Researcher, National Institute for
MPa-class ultra-high strength bolts, testing on the bolt products and evaluMaterials Science
showed that the tensile strength of the ating the decrease in axial force due to2009: Principal Researcher, National Institutenotched bar specimen varied greatly relaxation. Furthermore, the specificafor Materials Science
depending on the stress concentration tions of a hexagon nut compatible with
2016: Chief Researcher, National Institute forMaterials Science
factor, as shown in Fig.1. Therefore, the developed bolt were optimized; thefocusing on this point, the influence of height of the nut was 26.4 mm and theIncreasing the strength of bolts can shape and dimensions on the mechan- hardness of the nut was HV350-450.
reduce the number and size of bolts ical properties of ultra-high strength
As a result, we succeeded in creatingused in joints, leading to more com- bolts was investigated. Specifically, a 1700 MPa-class ultra-high strength
pact joints and improved construction we focused on reducing the diameter bolt with greatly improved tensile deefficiency. However, it is necessary of the shank portion of the bolt and al- formation capability (Fig. 3). Prototo overcome delayed fracture and im- lowing the shank portion to yield and type bolts were further mass-produced
prove the cold formability of the mate- deform plastically before the threaded from the steel material produced in 40rial and the tensile deformation perfor- portion to reduce the stress concentra- ton arc melting furnace, and the immance of the bolt products to develop tion at the threads and improve the ten- provement of the bolt’s tensile deforbolts with even higher strength than sile deformation capacity of the bolt.
mation performance was verified.
the F14T bolts with a tensile strength
Fig. 2 shows a schematic diagram ofof 1400-1490 MPa.
the manufacturing process and dimenFig. 3 Tensile Deformation Behavior
In this study, we performed basic re- sions of the shank preceding yield typeof Developed Bolt
search to control the mechanical prop2000
erties, especially tensile deformation
Fig. 2 Manufacturing Process andShape and Dimensions of
performance, of 1700 MPa-class ulDeveloped Bolt
1500
tra-high strength bolts (nominal sizeM22) in collaboration with researchNew thread
JIS threaders in steel materials, bolt manufac1000
turing, and civil engineering and construction. We successfully developed a
(mm)

4

5

Displacement (mm)JIS SCM440 (AISI4140)(TS=1403 MPa)

Stress concentration factor
April 2022 Steel Construction Today & Tomorrow 8

Feature Article: R&D on Advanced Mechanical Fastening Technology

Examination of High-strength Bolt
Fastening by OS Method

by Susumu Kuwahara, Associate Professor
Graduate School of Engineering
Osaka University

Weld Joining and Bolt Joining
Steel products are basic structural materials indispensable in the construction ofcivil engineering and building structures.
Compared to concrete, wooden and otherstructural materials, steel products offer
higher performance-far high strengthand superior workability. Whether astructure that makes maximum use of
these structural advantages peculiar tosteel products can be realized rests on
two tasks-how to effectively connect(join) the thin and slender steel products
and how to make these joined steel members behave stably (stiffening of members). Weld joining and bolt joining havebeen firmly established as the methods
for joining steel products through steady
improvements made in technology andjoining material production systems.
Currently, these two joining methods areproperly applied by taking into accounttheir application efficiency and economic advantages in addition to their dynamic performance.
Of the joints applied in steel-structurebuildings, the column-to-beam connection requires the most processing steps
to finish and serves as an extremely important section in terms of the building
structure and this joint is mostly formedby means of weld joining. However, diverse joining methods to form the column-to-beam connection by means ofhigh-strength bolt joining have thus far
been proposed that offer less qualitycontrol items than those in weld joining(refer to Table 1). Further, several bolt
joining methods have already been put
into practical use in building construction1).
In order to make extensive surveys
and research on high-strength bolt joining and other kinds of mechanical fastening in common use, the Japanese Societyof Steel Construction (JSSC) established
9 Steel Construction Today & Tomorrow April 2022

Susumu Kuwahara: After graduating from the Graduate
School of Engineering, Osaka University in 1992, he became
Assistant, School of Engineering, Osaka University in 1992 andthen Associate Professor at the School of Science and Technology, Kyoto Institute of Technology in 2005. He assumed his current position as Associate Professor, Osaka University in 2008.
He serves as a member of the Subcommittee on MechanicalFastening Technology and as a chief of the Subcommittee on
the Preparation of JSS Specifications Relating to the OS Method of the Japanese Society of Steel Construction.

the Subcommittee on Mechanical Fastening Technology in April 2015. It was established as a successor to the forerunner
Subcommittee on High-strength Bolt Fastening Technology of the JSSC. The members of the Committee consist mainly ofmen of learning and experience, structural designers, construction companies, bolt/
fastener makers and wrench makers.
This article introduces the experiments made and research results obtained
for the OS (offset slope) method (former
name: new yield point method), a highstrength bolt fastening method that constitutes the basis of mechanical fastening technologies for steel structures. The
OS method is an examination subject selected in the JSSC Technical Report No.
96 “Current and Future Developmentsof High-strength Bolt Joining Technology”2) published in 2013. The OS method compares with the fail-safe (FS) bolt
method and is one of the research subjects of the JSSC’s Subcommittee on
Mechanical Fastening Technology.

Emerging Need for Improved Bolt
Fastening Methods
The mainstream of high-strength bolt fastening methods applied in the constructionof civil engineering and building structures in Japan is the torque method employing mainly torque-shear (torshear)type high-strength bolts. Its advantage
lies in the ease of fastening and the factthat fastening finish can be visually confirmed with the fracture of pintails. With
this method, however, the torque coefficient changes due to the temperature at
the stage of fastening, storage conditions
and other factors, which is likely to affectthe axial force in bolt fastening. Further,fractured pintails turn to useless materials
after fastening to cause wastefulness.
To solve these concerns, examinations
were made of the OS method as a new bolt
fastening method. The yield point method,a basic approach for the OS method, is abolt fastening method with which the yieldstrength of bolts is detected from the changeof load current of an electric wrench motor

Table 1 Joining Methods
Angle joining

Split-Tee joining

End plate joining

Outer diaphragm joining

Brace joining

Others (column-to-beam joint)to control the fastening axial force. Accordingly, a larger fastening axial force than thatof torshear-type high-strength bolts can be
introduced in bolts used in the OS method. Further, because the fastening finish is
controlled based on the bolt strength (yield
point) less in deviation, it can be expectedthat the OS method will allow the introduction of a stable axial force that is almost unaffected by the torque coefficient and thestiffness (thickness of the structural member to be fastened and bolt length) at the final fastening stage.
While there is no application record of
the yield point method in the field of building construction, the yield point method isthe bolt fastening method that has accumulated a rich application record in theconstruction of Honshu-Shikoku connecting bridges, the Banshu Bridge and many other civil engineering structures. Furthermore, its application is accepted under
the Japanese Specifications for Highway
Bridges (JSHB). Meanwhile, the yield
point method has shown no steady spreadin its application due to the reasons cited,that is: The size of wrench is larger thanthat of the shear wrench in current use,which results in inferior handling efficiency; and further, in the yield point method,using the common hexagon bolt set andexternal reaction force-type wrench, thebolt is fastened by receiving the bolt reaction force with the neighboring bolt.
In order to solve these problems involved in bolt fastening, in the OS method, reaction force washers are used inplace of common washers. The reaction
force washer (Photo 1) is designed so thatthe washer can receive the reaction force
torque by itself. Bolt fastening performance similar to that in torshear bolt fastening can be obtained by fastening the bolt
using the wrench for the yield point meth-Fig. 1 Outline of Bolt Fastening by Means of OS Method

Free-threaded
lengthMember to befastened

Nut

Reaction force washer
Outer sleeve
Inner sleeve(a) Before fastening(b) During fastening

Photo 1 Reaction force washer

od developed to adapt to the use of the reaction force washer (refer to Fig. 1). With
this OS bolt fastening method, excess
force is not applied to the neighboring bolt,
and fastening can be attained regardless ofthe bolt arrangement. Further, this is rational as a reaction force mechanism as the reaction force is received mainly by the bolt.
In addition, the OS method offers other notable application advantages: No

waste material is discharged because of
the elimination of pintails. The unified
fastening method can be applied regardless of the type of bolt (hot dip-galvanized and other coated bolts). Regarding the bolt configuration used in the OS
method, it is possible to change the bolt
head from the hexagonal shape of conventional high-strength hexagon bolts to
the round shape found in torshear-typehigh-strength bolts, which allows for noneed for bolt-head washers. Also, it ispossible to save the use of materials dueto the elimination of the application ofbolt-head washers and the lack of waste
discharge due to the elimination of pintails.
Table 2 shows the respective featuresof the OS and other bolt fastening methods. In cases when the stabilized highbolt axial force can be introduced in bolt
fastening due to the adoption of the OS
method, it will be possible to settle high-Table 2 Comparison of Various Bolt Fastening Methods
Torshear bolt method

Nut rotation method

Yield point method

OS method

Fastening
axial force

Bolt elastic range

Bolt plastic range (large)

Bolt plastic range (small)

Effect on fastening
axial force

Effect of torque coefficient:
Large

Effect of primary fastening:
Large
Effect of fastening length:
Large

Effect of torque coefficient: Small
Effect of primary fastening: Small
Effect of fastening length: Small

Fastening (wrench)

Shear wrench to receive
fastening reaction force
using bolt pintail

Torque wrench

Outer reaction force-type
wrench for yield point
method employing
neighboring bolt

Wrench for yield point
method to receive thefastening reaction force using
reaction force washer

Fastening control

Marking
Pintail fracture

MarkingMarkingMarking(new control method)Bot set applied

Torshear-type high-strength
bolt set

JIS high-strength bolt set
Hot-dip galvanizedhigh-strength bolt set

JIS high-strength bolt set

Bolt set employing reaction
force washer(regardless of kind of bolt)

Material saving

Disposal of pintail

No need for pintail

No need for pintail

No need for pintail

April 2022 Steel Construction Today & Tomorrow 10

er design sliding strength than the conventional level. Extensive experiments
have been made for the practical application of the OS method, an outline ofwhich is explained in the following:
Axial Force of Bolts in the OS
MethodIn experiments made for the practicalapplication of the OS method, an electric wrench for use for the OS method (TONE-made) was adopted and theaxial force introduced in the bolt (axial force of the bolt) was measured mainly employing the electric axial force meter. Meanwhile, a short-length bolt towhich the electric axial force meter cannot be applied was fastened to the practical steel plate employing the bolt gauge.
The bolt targeted in the experimentwas 10T (bolt strength≧1,000 N/mm2),
M22 (shank diameter: 22 mm), and theexperiment was conducted by the combined use of high-strength hexagon bolts,
nuts and reaction force washers (Photo2). The bolt was fastened in the procedure of “primary fastening→ marking→final fastening” similar to that in practical bolt fastening. The experiments were
implemented at Osaka University.

Photo 2 Bolt set used in the experiment• Outline of Experiments

Table 3 shows the variables used in theexperiment. The structural member to befastened and the bolt length (thicknessof the structural member to be fastened)

are the variables that verify the effect of
the stiffness of the structural member tobe fastened. The offset value is the control variable that is settled by the electric wrench. In the table, the offset value
indicates the calculated plastic distortion
value of the free-threaded section where
the free-threaded length is 17 mm, andthe offset value at 1.0% in common use
in the conventional yield point method is
set as a standard offset value.
Three kinds of axial force in primary
fastening were settled: 50 kN supposed
to be applied in the field of building construction, 140 kN supposed to be appliedin the field of civil engineering, and theaxial force in finger tightening. Twokinds of torque coefficients were settled: the standard torque coefficient andthe higher torque coefficient in the caseof using non-lubrication nuts. Four kindsof free-threaded length were settled: selection in terms of the bolt length to thethickness of the structural material to befastened and selection by taking into account the dimensional tolerances of bolt
length, screw section length and washer
thickness.
Based on these variables, the effects
are understood in the experiments inthe case of fastening the bolts with different free-threaded lengths by the useof a wrench for which the offset value
is fixed in the practical fastening operations. For the bolt manufacturer and bolt
length, the difference of bolt strength
caused by differences in manufacturing
lots was also taken into account. In theexperiments, a total of 1,800 bolts were
subjected to fastening-30 bolts respectively for 63 kinds of combinations of
the above-mentioned variables (10 bolts
each for 6 kinds using the bolt gauge).

• Precise Control of Key Values

Fig. 2 shows an example in which thebolt axial force and the nut rotation angle
controlled using an electric wrench for

Fig. 2 Relation between Bolt Axial
Force N and Nut Rotation Angle
θ and Example of Fastening
Results
N (kN)
350
300(Dotted line: Offset straight line;
x: Fastening finish point)

0.5% offset

250
200
150

1.2% offset

100
50
0

0

50

150

θ (°)

use for the OS method are plotted for the
relationship between the bolt axial force
and the nut rotation angle. It can be understood from this figure that the bolt axial force and the nut rotation angle are
precisely controlled.
Meanwhile, the example shown in
the figure indicates cases in which thebolt was fastened using the electric axial
force meter, and there are cases in which
the nut rotation angle at the stage of fastening finish surpassed 120°-the target value of the nut rotation methoddue to low fastening stiffness. However,
the average nut rotation angle in the caseof fastening steel plates (offset value of
1.0% and bolt length of 85 mm) is 114°,
which is lower than 120°.

Table 3 A List of Variable Used in the Fastening Experiments
Structural member to be fastenedElectric axial force meter, steel plate

Bolt length

55 mm, 85 mm, 100 mm, 130 mm

Offset value

0.5%, 0.75%, 1.0%, 1.2%

Torque coefficientStandard (average: 0.125), high (average: 0.162)

Primary fastening axial force

50 kN, 140 kN, finger tightening (FT)Free-threaded length

8 mm, 12 mm, 17 mm, 20 mm

Bolt manufacturer

Company A, Company B, Company C, Company D, Company X

11 Steel Construction Today & Tomorrow April 2022

100• Effect of Variables on Fastening

Axial Force
Fig. 3 shows part of the effect of experimental variables on the bolt fastening axial force. Every vertical axis in the figure
indicates the bolt fastening axial force,and every horizontal axis indicates theexperimental variable. The mark ♦ in the
figure indicates the average bolt fastening axial force by variable, and the boldline on ♦ indicates the range of “2 times
the ±standard deviation for the averagevalues of bolt fastening axial force.” In
addition to the effects of major experimental variables, the figure shows differences in the effect of the primary fastening tension force (50 kN, 140 kN; finger

tightening or FT: about 10 kN).
The effect of the thickness of thestructural member to be fastened, the bolt
length, the offset value and the torquecoefficient on the fastening axial force isless, and the axial force is nearly 300 kN.
The effect of the axial force in primary
fastening and free-threaded length on thefastening axial force is also less.
Regarding the variable of the bolt
manufacturer (bolt yield strength) with
an effect larger than other variables, eventhe average deviation of the fastening axial force remained within a maximum of
6%. The reason for this is attributable tothe difference in bolt strength dependingon the bolt manufacturing lot, and thedeviation becomes slight in the case of
making the bolt axial force dimensionless in terms of the bolt strength.
When the torque coefficient is highdue to the use of non-lubrication nuts,
the bolt yields in an earlier stage thanthe case of standard torque coefficientsand the stiffness lowers due to the torqueworking on the bolt at the stage of fastening. Because of this, the axial force ofthe bolt also lowers by 4%. When the OS
method will be put into practical use, it isconsidered desirable that bolt manufacture control is managed in terms of thestandard torque coefficient.

Fig. 3 Effect of Experimental Variables on Fastening Axial Force (1)Average value
350█ Average value ±2σ
350

Fastening axial force (kN)

300

300
250

205 kN (F10T, M22)

200

150

Primary fastening axial force (kN)

100

FT

50

140

FT

50

150
140

100

Torque coefficientStandard

0

350

250

▼ Design axial force in current use:

200

50

Fastening axial force (kN)

50

High

▼ Design axial force in current use: 205 kN (F10T, M22)

Primary fastening axial force (kN)
50

140

140

0

0.75

350

Fastening axial force (kN)

300

250

250

150
100
50

▼ Design axial force in current use: 205 kN (F10T, M22)

50

140

FT

50

50

140

1.00

1.20

Fastening axial force (kN)

Design axial force
in current use:
▼ 205 kN (F10T, M22)

150
140

FT

50

140

100
Stiffness

Bolt length (mm)
85

0

200

Primary fastening axial force (kN)FT140(b) Offset value

300

200

50

Offset value (%)0.50(a) Torque coefficient

50

50
110

(c) Bolt length

130

Low

High

0

(d) Stiffness of member to be fastened

April 2022 Steel Construction Today & Tomorrow 12

Fig. 3 Effect of Experimental Variables on Fastening Axial Force (2)Average value
350█ Average value ±2σ

Fastening axial force (kN)

300
250
200
150
100
50

▼ Design axial force in current use: 205 kN (F10T, M22)

Free-threaded length (mm)
8

12.5

17

20

8

12.5

350

20

Primary fastening axial force (kN)
50

0

17

140

(e) Free-threaded length (bolt length: 85 mm)
Fastening axial force (kN)

300
250
200
150
100
50

▼ Design axial force in current use: 205 kN (F10T, M22)

Bolt manufacturer
A

B

C

D

X

A

B

D

X

Primary fastening axial force (kN)
50

0

C

140

(f) Bolt manufacturer (bolt length: 85 mm)• Higher Axial Force

Fig. 4 shows the frequency distributionof bolt axial force in the OS method.
This figure was prepared by excluding
test specimens using the non-lubrication nut from among the variables examined in the fastening experiment andby setting as a sample the test specimens(1,700 specimens in total) using the variable within the range for which practicalapplication is supposed.
As seen in the figure, the average fastening axial force is 301.1 kN,
the standard deviation σ is 7.6 kN,
and the average-3σ (3σ reliable axial
force) is 278.3 kN. The design bolt axial force in current use for F10T (boltstrength≧1,000 N/mm2), M22 is 205
kN. It was thus confirmed from the re-Fig. 4 Frequency Distribution of Axial Force of Bolt Fastened by the Use of
New Yield Point Method (1,700 Bolts)
Frequency
500
450
400
350
300
250
200
150
100
50
0

13 Steel Construction Today & Tomorrow April 2022

3σ reliable axial force:
278.3 kN

26

0

26

5

27

0

27

5

28

0

28

5

29

0

29

5

30

0

30

5

5
0
5
0
32
32
31
31
Fastening axial force (kN)sults of these experiments that an axial
force in terms of the average axial forceof 1.46 times the current level and a 3σ
reliable axial force of more than 1.35
times the current level can be stably introduced in bolt fastening by the use of
the OS method.
Relaxation of Bolt Axial ForceAn experiment was conducted to grasp
the effect of the introduction of highstrength bolt axial force employing the
OS method and the adoption of reaction
force washers on relaxation. The bolt
subjected to this experiment was 10T,
M22. Table 4 shows the variables used in
the relaxation experiment. The transitionin the bolt axial force was measured targeting 5 bolts respectively for 16 kindsof combinations of various experimental
variables. Fig. 5 shows examples of theexperimental results over a 2-month period after the introduction of axial force.
Almost no effect was observed of axial force and washer configuration on relaxation as shown in the figure, and thus
it can be said that the relaxation level by
the use of the OS bolt fastening method is nearly the same as that by the useof other bolt fastening methods. The reduction rate of the bolt axial force to theinitial-stage bolt axial force (bolt axial force after 30 seconds from fastening
finish) was about 3% in the case of grit
blasting and 8~12% in the case of inorganic zinc-rich paint blasting.

Future Development and Tasks
about OS Method
As explained in the above, the OS method is a high-strength bolt fastening method having high application potential. The
research results introduced above were
published in detail in the JSSC’s Technical Report No. 118 (November 2019):
Examinations of High-strength Bolt Fastening by Means of the New Yield Point
Method (OS Method)3). In 2020, JSSC
newly established the Subcommittee on
the Preparation of JSS Specifications Relating to the OS Method to promote theextensive examination of the practicalapplication of the OS method.
The current state and future development and tasks involved in the promotion of the practical application of the OS
method are introduced in the following:• Electric Wrenches for Use with
the OS Method
This wrench is a key to promoting thepractical application of the OS method, and continued examinations on thewrench are being called for. In the examinations, fastening experiments wereconducted mainly targeting the highstrength bolt set of M22, F10T.
Then, a wrench was manufactured
that can be applied for M16, hot-dip galvanized high-strength and other bolts andoperation tests were conducted, in which
experimental results similar to those of
M22, F10T were obtained. In 2020, an-

Table 4 A List of Variables Adopted in Relaxation Experiment
Axial force of bolt

226 kN (standard bolt axial force), 300 kN (OS method)

Washer configuration

Plain washer, reaction force washer

Friction surface treatment method

Grit blasting, inorganic zinc-rich paint blasting

Bolt length

85 mm, 130 mm

Fig. 5 Examples of Relaxation Experiment Results (Bolt Length: 85 mm)
Axial force survival rate (%)

Axial force survival rate (%)

100

100

90

90

80

Grit: 226 kN

70

Inorganic zinc: 300 kN
Inorganic zinc: 226 kN

60
50

80

Grit: 300 kN

1

10

100

1000 10000 100000
Lapse of time (min)Grit: Reaction force washer
Grit: Plain washer

70

Inorganic zinc: Reaction force washer
Inorganic zinc: Plain washer

60
50

1

10

100

1000 10000 100000
Lapse of time (min)other type of wrench was manufactured
that is lighter in weight and smaller insize than those manufactured at the stageof initiating the experiments.

• High-strength Bolt Set for Use

with the OS Method
It will be possible using the OS method to adopt bolts with a bolt head likethe round head of torshear-type bolts andto eliminate the application of bolt-head
washers in cases when the proper measure to prevent axis rotation is provided
under the bolt head. Because of no needfor pintails in the OS method, necessary
materials can be saved by about 19% in
the case of the M22×85 mm hexagon
bolt compared to the case of hexagon
high-strength bolt sets.

• Confirmation of Delayed

Fracture Resistance
Currently, high-strength hexagon bolt
sets for use for the yield point method
are provided for the construction of steel
bridges. While their dimensions, configuration and mechanical properties are
the same as those of conventional highstrength bolt sets, its delayed fracture resistance is examined by taking into account bolt fastening by the use of theplastic range of bolts. This high-strength
hexagon bolt set for use for the yield
point method has a rich application record in the construction of Honshu-Shikoku connecting bridges, and thus thepossibility of the occurrence of delayed
fracture is considered low, but continued
examinations are being called for to improve its delayed fracture resistance.
To cope with such a situation, the following concept may also be feasiblethe delayed fracture resistance is to be
improved by purposely adopting bolts
with low strength and not by changing
the bolt axial force using the OS method.

• Post-fastening Inspection andFastening Control
In order to inspect the bolt after fastening
by the use of the OS method, the measurement of nut rotation by means ofmarking is considered appropriate. The
approach to confirm fastening by meansof marking has shown no change since
the start of application of high-strength
bolts, and thus it is required to develop
new fastening inspection and confirmation methods that replace the conventional marking method that take into account the higher fastening efficiency.
April 2022 Steel Construction Today & Tomorrow 14

Given this, expectations are high forthe development of advanced fastening
inspection and fastening control methods employing IC tags, mobile terminals, MR Gear and other advanced technologies.

• Unified Fastening/Inspection

Methods for Various Kinds of
Bolts
Capitalizing on the unified fastening/inspection methods, it becomes possible toconduct fastening control for any kindof bolt such as high-strength hexagon
bolts, high-strength hot-dip galvanizedbolts and other coated bolts. In addition,
the unified fastening/inspection methods
allow not only for the unification of thespecifications of wrenches used for bolt
fastening but also the mitigation of thetime and cost burden required for bolting
workers to acquire necessary technologies and qualification. In this regard, it
will be necessary to prepare training materials in the future.

• Joint Design Method

It is possible to improve design sliding yield strength by the use of the OS
method. However, because the allowablestrength of high-strength bolts is settled
and retained-strength joints are required
to be provided based on the BuildingStandard Law of Japan, it is impossible
to simply decrease the number of bolts
to be used. Thus, it becomes necessary toestablish a joint design method that conforms to the OS method.
In cases when this joint design method will be put into practical application, it will be possible to design morecompact joints than the joints of highstrength bolts in conventional use, which
will thus allow the saving of energy andmaterials, and the saving of labor in bolt
fastening operations as well. In addition, because this joint design method
is a technology that can be applied not
only to heavy, thick, high-strength steel
products but also general-purpose steel
structures or a wider range of general steel products, this method is expected to bring about far-reaching effects. In
examining the maintenance and repair ofsteel bridges, an emerging task surrounding the social infrastructure, the joint design method that conforms to the OS
method will serve as an effective means.

15 Steel Construction Today & Tomorrow April 2022

Towards Improved MechanicalFastening Technology
Weld joining, mechanical fastening andother diverse kinds of joining methods
by means of the combined use of these
two methods are currently being applied.
In doing so, certain criteria are cited todetermine what kind of joining methods
should be selected at the stage of designof joints. Among these judgement criteria are not only the change in the condition at the steel-frame manufacturingsite such as reducing number of welding engineers and ongoing technical development of welding robots but also
the change in conditions at the designsite such as in the standardization of bolt
joint design and improvement of approval/licensing environments that allows theeasy application of new joining methods.
Moreover, these criteria are apt to be affected by global economic conditions.
On top of this, in the case of examining the decreasing number of weld engineers and subsequent soaring of personal
expenses, and further how to secure thequality under the situation of ongoing
global operations of product-manufacturing sites, it is fully accepted that there
will be an increasing need for a method
to form steel-structure joints by meansof mechanical fastening with less quality
control items compared to weld joining.
In the case of forming joints by meansof mechanical fastening, we consider
that the OS method can serve as an important, basic technology for use for fastening high-strength bolts.
Acknowledgement
These experiments were conducted withthe aid of the JSPS Scientific Research
Subsidy of the Japan Society for the Promotion of Science and Steel-structure
Research/Training Subsidy of the Japan
Iron and Steel Federation. Certain helps
and advice were given from the membersof the Subcommittee on Mechanical Fastening Technology, the Working Groupon Joining Elements and the Working
Group on Structures of the Japanese Society of Steel Construction. We express
our thanks to all concerned.
References
1) Japanese Society of Steel Construction:
Towards diffusion of column-beam joints
formed by mechanical fastening, JSSC
Technical Report No. 124, 2021
2) Japanese Society of Steel Construction:
Current and future developments of highstrength bolt joining technology, JSSC
Technical Report No. 96, 2013
3) Japanese Society of Steel Construction:
Examination of high-strength bolt fastening by means of the new yield point
method (OS method), JSSC Technical
Report No. 118, 2019

Photo 3 Technical Report No. 118: Examination of High-strength Bolt Fastening by OS Method

Special Article: Stainless SteelSUS Lining Applied in the Jacket-type Pierat Tokyo International Cruise Terminalby Rokusui Yui, JFE Engineering Corporation
Increasing Size of Cruise Ships
International cruise ships have recently
shown a trend towards larger sizes. Because of this, large-size cruise passenger
ship that enters the Port of Tokyo cannot cross the Rainbow Bridge, a suspension bridge constructed in the port, andaccordingly there have been many cases in which large-size ships cannot comealongside the Harumi Passenger Ship Terminal (Harumi Wharf). (Refer to Photo 1)
In order to accept these large-size
cruise ships that enter the Port of Tokyo,
the Tokyo Metropolitan Government
planned the construction of a new cruise
terminal at the Tokyo Waterfront City located outside the Rainbow Bridge-the
Tokyo International Cruise Terminal towhich world-class cruise ships can comealongside. Construction started in 2015,
and the new cruise terminal started oper-

ations in 2020.
The new terminal project proceededwith a lot of construction work, among
which the major work was:
• Removal and relocation of existing structures• Construction of pedestrian bridge• Foundation work for terminal facilities• Mooring wharf construction (pier anddolphin)Terminalbuilding construction•
For the foundation work for the terminal facilities and the mooring wharf construction, a jacket-type pier method was
adopted from the viewpoint of reducing
the construction term and for economic
advantage (Photo 2).
Jacket-type Pier
The jacket-type pier was developed as astructure for use as an offshore platformⒸTokyo Metropolitan Government Bureau of Port and Harbor

Harumi Wharf

52 m

Rainbow Bridge
New Wharf
Port of Tokyo

Photo 1 Location of conventional and new
wharves in the Port of Tokyo

Photo 2 Steel jacket used for mooring pierconstructionused mainly for developing ocean-floor resources. It is a structural type applied to the
reduction of construction work to a minimum level and for shortening the on-site
construction term in the sea area where water depth is high and oceanographic/meteorological conditions are severe. Specifically, a jacket (steel pipe truss structure)assembled on land is installed on steel pipe
piles driven into the seabed, and the jacket and pipe piles are integrated by means of
welding or grouting to allow for the jackettype pier to resist the external force working on it.
When compared to a conventional piletype pier, a jacket-type pier is lighter interms of the total weight and allows the mitigation of seismic inertia force in the eventof an earthquake. In addition, its rigidity
is comparatively high, and thus the deformation occurring when the external force
works when bringing a ship alongside thepier can be suppressed to a low level.
Outline of Steel Jacket
Fig. 1 shows a grand plan for the newwharf. The foundation section (41 m inwidth, 252 m in total extension) of theterminal pier is composed of 4 jackets,and the 370 m-long mooring pier sectionof the mooring wharf (30 m in width,
430 m in total extension) is composedof 7 jackets. These jackets were installed
employing a crane barge, as shown in

Fig. 1 Grand Plan for New Wharf

Terminal pierConnecting passage pierJacket-A
48 m
Access slab
2m

Terminal pier (L=252 m)
Jacket-B
Jacket-C
70 m
72 m

Jacket-D
60 m

Extension

252 m

Width

41 m

Number of jacket

Terminal

Extension
Width
41 m

Pedestrian
bridge4

Mooring wharf
430 m*
30 m

Number of jacket
7*Jacket extension 370 m
30 m

Access slab

Dolphin
L=60 mJacket-B
30 m

Jacket-C
60 m

Jacket-D
60 m

Jacket-E
60 m
Mooring pierMooring wharf (L=430 m)

Jacket-F
60 m

Jacket-G
50 m

Jacket-H
50 m

April 2022 Steel Construction Today & Tomorrow 16

Photo 3 Installation of jacket (mooring pier)using crane ship

Photo 3.
The pier section was designed as aseismically-reinforced pier that can deal
with level 2 seismic motion so that it canbe used for the transport of emergency
supplies in the event of a disaster.
The upper half of the jacket in common use is exposed to splash and tidal
zones, and thus for the steel jacket, its
application environment is very severe.
SUS Lining Applied in the Jacket
As a countermeasure against corrosion of the steel jacket, the conventional method thus far adopted is the combined use of super high-build coating(heavy-thick corrosion-protection coating) and cathodic protection. However,from considerations to the lifecycle cost,seawater-resistant stainless steel lining(SUS lining) is increasingly being adopt-

ed for part of the section to which the super high-build coating is applied.
The section to which SUS lining is applied is the standard part of steel pipes exposed to the splash and tidal zones (Fig. 2).
The repair frequency of steel jackets exposed to severe corrosion environments,
splash and tidal zones, can be reduced by
the use of SUS lining having high durability and high corrosion resistance. In addition, easy maintenance becomes feasible
with SUS lining. (See Photo 4)
Similar SUS lining has been appliedin the pier of the D runway of Haneda
Airport for which extralong-term years
are required to retain durability.

were properly applied with the boundaryof L.W.L.-1.5 m as shown in Fig. 2.
For the SUS lining in this wharf,
SUS312L stainless steel with a thicknessof 0.4 mm was applied as the basic lining
member. In the boundary section between
SUS lining and super high-build coating,super high-build coating is lapped over
the SUS lining to continuously protect theboundary section from corrosion.

Maintenance-saving SUS Lining
In the repair of coastal steel structures
exposed to splash and tidal zones, drying-up and other large-scale preparations
are required. Depending on the situation,
there are cases in which operations of the
SUS Lining Applied in the New
facility in use need to be suspended durPier Construction
ing the repair period.
Regarding the corrosion-protection methIt is considered that the application
od applied in the pier of the Tokyo In- of maintenance-saving corrosion-protecternational Cruise Terminal, super high- tion measures in important facilities andbuild coating and cathodic protection difficult-to-maintain structural sections
wi l l b r i ng about
Fig. 2 Plan of Corrosion Protection of Jacket
large advantages inSuper high build coating
terms of efficient facility operations andmaintenance cost reCoatingStandard part
duction.
methodof steel pipe
SUS lining
We hope that theconstructionof steel
L.W.L -1.5 m
structures employing
Cathodic
SU S l i ni ngs wi l lprotection
increase so as tomethodcontribute to thesubstantial improvement of maintenancesaving infrastructure.
Super highbuild coating

Organic zinc rich primer

Coating thickness

20 μm

Epoxy resin coating

Coating thickness 2500 μm

SUS lining

SUS312L

Thickness

0.4 mmⒸ Tokyo Metropolitan Government Bureau of Port and Harbor

Photo 4 SUS lining just after setting on jacket

Photo 5 Upper girder of steel jacket at terminal side
17 Steel Construction Today & Tomorrow April 2022

Photo 6 Full view of Tokyo International Cruise Terminal

JSSC Events

The 7th China-Japan-Korea Tall Building
Forum in 2021

by Dr. Masayoshi Nakai, Director of CTBUH Japan Structures Committee, International
Committee of Japanese Society of Steel Construction (JSSC); Engineering Fellow, Engineering
Department, Takenaka Corporation
About the China-Japan-Korea Tall
Building Forum
This forum is an international conferenceon high-rise buildings organized by academic experts and structural engineersfrom China, Korea, and Japan as part ofthe initiatives of the CTBUH (Council
on Tall Buildings and Urban Habitat) in
Asia region.
Professor Emeritus Sangdae Kim at
Korea University, who served as Chairmanof the CTBUH from 2009 to 2011, proposed this idea in 2012, and after discussions among Professor Guoqiang Li (China representative of CTBUH at that time),
Professor Emeritus Akira Wada at Tokyo
Institute of Technology, Professor Emeritus Yukio Tamura at Tokyo Polytechnic
University and members of the CTBUH
Japan Structures Committee, International Committee of Japanese Society of Steel
Construction, it was decided to jointly holdthe conference in three countries.
As a rule of this one-day forum, a total of nine people at a minimum, threeeach from Japan, China, and Korea, will
give a lecture on experimental or analytical research on high-rise buildings,
structural design and construction of actual tall buildings, and so on. In addition
to the forum, a site tour to the high-risebuildings under construction or completed at the venue will also take place.
Since it was first held in Shanghai in
2014, it has been held in three countries
every year: 2015 (Seoul), 2016 (Tokyo),2017 (Chongqing), 2018 (Busan), andthe sixth in 2019 was held in Nara, theancient capital of Japan.
The 7th China-Japan-Korea Tall
Building Forum, Hybrid Forum in 2021
The seventh forum was scheduled to beheld in Suzhou, China in 2020, but it was
postponed to last year due to the COVID-19 pandemic. A hybrid conference
based at Tongji University in Shanghai
was proposed. In the afternoon of Tuesday, November 16, 2021, the seventh forum was held, using the videoconference
system “Zoom” for Japanese and Koreanparticipants. In addition, this year’s forum

Organizer members mainly from Tongji University in China (view immediately after
the forum); Fourth from the right is Prof. Guoqiang Li, the representative of China

is organized by CHEE-ASC (Committee of High-rise Habitat EnvironmentThe Architectural Society of China) andco-organized by the CTBUH Japan Structures Committee and the Korean Council
on Tall Buildings and Urban Habitat.
There were about 30 Chinese participants at Tongji University and a peak of
about 200 online participants from China, Japan and Korea, and active questions and discussions took place at eachlecture, including the use of the Zoom
chat function.
At the beginning of the forum, Professor Guoqiang Li gave opening addresses
as the representative of CHEE-ASC, followed by Professor Yuko Tamura from
Chongqing University as the representative of Japan and Dr. Kwangryang Chung(President of Dongyang Structural Engineers Group Co., Ltd.) from Korea.
After that, there were 5 lectures on
structural design, research and construction management of high-rise buildings from China, 3 lectures on case studies, structural design and construction ofhigh-rise buildings from Korea, and 3 lectures on structural design of tall buildings
from Japan (11 lectures in total). The outline of each lecture is described below.
• First, Dr. Kyoung Sun Moon, Associate Professor at Yale University, gave alecture on the case studies of conjoined
mega-tall buildings, including those histories, structural characteristics and sustainability.
• “Suzhou IFS (International Finance
Square)” introduced by ECADI (East
China Architectural Design & ResearchInstitute) is a skyscraper with a heightof 450 m and 95 stories that was com-pleted in 2019 in Suzhou, the ancient
city of China, and served for hotel, office and residence. The outline of thestructural engineering, including theperformance-based seismic design, wasexplained.
TJAD(Tongji Architectural Design Group•
Co., Ltd.) announced the structural designof “Silk Road Centre Building” plannedin Xian, China, which has a height of
498 m, 101 stories and a “damped outrigger” system.
• Dr. Kwangryang Chung explained thedesign concept and structural design ofthe “Cheongna City Tower (Tower Infinity) ” which is to be built near Incheon
International Airport in Seoul. The tower
is an entertainment facility that includes
an observation deck, in which the invisibility illusion will be achieved witha LED façade system. It will be about
450 meters tall, making it the sixth tallest tower in the world when completed.
• Introduced by Mr. Ahmad Abdelrazaq
from Samsung C & T Corporation of Korea, “Merdeka PNB 118” is a 118-story
complex (consisting of office, residence,
hotel and retail) under construction in
Kuala Lumpur, Malaysia and will be 644
meters tall, making it the second tallest
building in the world after Burj Khalifa.
In addition to the outline of the structuraldesign, details of construction planningsuch as quality control of cast-in-place
concrete, etc. and current construction
situation were explained. It should be
noted that Leslie. E. Robertson (whopassed away at the beginning of 2021)
was involved in the structural design ofthis building in the fundamental designphase and ARUP was responsible forApril 2022 Steel Construction Today & Tomorrow 18

structural engineering of record.
ShanghaiConstruction Group introduced•
smart construction management and risk
management based on information technologies on a high-rise building named“New City Center” under construction
in a dense urban area of Shanghai.
TongjiUniversity presented two research•
results: an experimental study on theseismic damage characteristics of RC
shear walls of high-rise buildings, and astudy on the dynamic characteristics of
the “damped outrigger” system, in whicha damping device is installed between
the outrigger tip and the outer column.
In• the lectures from Japan, Mr. Tomonobu Isobe from Taisei Corporation introduced the structural design of a high-risebuilding, in which a seismically-isolated
layer is placed between the middle-tolow stories (used for office and retail) ofsteel framed structure and the upper sto-ries (used for residence) of RC structure.
In addition to the characteristics of the
mid-story isolation system and its performance-based seismic design (PBSD),
detailed explanations were given on the
CFT, the seismic isolation device, andthe well designed joint system with thecast-in-place concrete column.
Mr.
• Shunsuke Nakajima from Obayashi
Corporation introduced a “dual frame
system” of a high-rise building in which
a rigid RC core frame is connected toa base-isolated RC frame independently surrounding this core with hydraulicdampers. The former, the latter is servedfor parking lot, residence, respectively.
The following were explained in detail:concept and the PBSD of this system,
construction method using precast concrete member and its actual process.
At• the end of the forum, Mr. Hidenori Karasaki from Nihon Sekkei Inc. gave a lec-

ture on a case of realizing an RC high-risebuilding with a high aspect ratio of 6.0 by
a vibration control system incorporating
oil dampers between twin RC core walls.
This building has a height of 237 m and 54
stories, and will be served for residence,
hotel and retail. The characteristics, analytical model and the PBSD of this damping
system were explained in detail.
Towards the 8th China-JapanKorea Tall Building Forum in 2022
In closing, Prof. Guoqiang Li thanked
the participants for their interesting presentations and meaningful discussions
at this forum, which unfortunately took
place online due to the COVID-19.
Finally, the nearly 5 hour forum cameto a successful conclusion with hopesthat the 2022 forum will be held in Korea in one place.

JSSC International Committee

Message from the Chairman

by Hiroshi Katsuchi, Chairman, International Committee(Professor, Yokohama National University)
The Japanese Societyof Steel Construction(JSSC) has conducted awide range of activities
pertaining to steel construction, among which
are surveys and research,technological development and the spread ofsteel construction for Japan and overseas. At
the same time, it has promoted tie-up operations with related overseas organizations.
Aimed at spreading Japan’s steel construction
technologies and developing overseas markets, the JSSC’s International Committee tookcharge of editing Issue No. 64.
Issue No. 64 features an article titled“Examination of High-strength Bolt Fastening by OS (Offset Slope) Method”-aresearch initiative aimed at developing thelatest mechanical fastening technologies forsteel structures. The OS method has notablefeatures. Specifically, in high-strength bolt
fastening by means of the OS method, it ispossible to introduce more stable and larger axial force than that in torshear-type highstrength bolt fastening, and it is also possibleby the use of reaction force washers to put inpractice more rational fastening with higher
efficiency than that in the conventional yield
point method. In this feature article, experiments made toward the practical applicationof the OS method are introduced.
In the Special Article: Stainless Steel inthis issue, the Tokyo International Cruse Terminal is introduced in which stainless steellining was applied to its jacket-type pier.
In addition, this issue introduces the JSSC
Commendations for Outstanding Achieve-

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
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Phone: 81-3-3516-2151 Fax: 81-3-3516-2152
URL http://www.jssc.or.jp/english/index.html

19

ments in 2021 in the field of steel construction (five projects) and thesis (three papers).
In the page of JSSC Events, an outline
is reported of the 7th China-Japan-Korea
Tall Building Forum held at Tongji University, China on November 16, 2021,
via a remote conference system. The Forum is one of the operations of CTBUH.
Throughout 2021 a variety of global activities were greatly affected by COVID-19,
and many new ingenious schemes were introduced, including the promotion of international activities using remote access tools
or services. The impact of COVID-19 is expected to continue in 2022, but we want to
expect new developments. We would likefor everyone to understand the activities of
JSSC and at the same time we would like tohear your opinions at any time.

© 2022 The Japan Iron and Steel Federation/Japanese Society of Steel Construction
Edited byCommittee on Overseas Market Promotion, The Japan Iron and Steel Federation
Chairman (Editor): Keiji AndoP u b l i s h e d t h r e e t i m e s p e r y e a r, S T E E L C O N S T R U C T I O N TO D AY &TOMORROW is circulated to interested persons, companies and publicorganizations to promote a better understanding of steel products and theirapplication in the construction industry. Any part of this publication may be
reproduced with our permission. To download content (PDF format), please go
our website at: https://www.jisf.or.jp/en/activity/sctt/index.html. We welcome yourcomments about the publication and ask that you contact us at: sunpou@jisf.or.jp.