No. 38 April 2013

STEEL CONSTRUCTIONTODAY & TOMORROW

http://www.jisf.or.jp/en/activity/sctt/index.html【 c h o 】
“超 (cho)” in Japanese, or “super” or “ultra” in English
Extremely; Beyond a particular limit

This issue, No. 38, features the advanced
super high-rise building technologies in Japan.
Special Issue: Japanese Society of Steel Construction...

JSSC Prizes 2012
1 SkyPark

2 R&D Center Building
Employing 1,000
N-grade Steel3 Seismic Measuresfor Existing Building

4 Tokyo Gate Bridge

JSSC Thesis Prizes 2012

5 Fracture Behavior of Electro-slag Weld
5 Plastic Deformation Capacity of Steel Column
6 Effect of Weld Shape on Ductile Crack

Published Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel Construction

Special Feature:
Advanced High-rise Building Technologies in Japan
7 Seismic Design

8 Wind-resistant Design

11 ABENO HARUKAS

9 Sony City Osaki

13 ARK Hills Sengokuyama Mori Tower

15 Loop Road No. 2 Project

17 Otemachi 1-6 Plan

19 JSSC Symposium; To Our Readers

JSSC Prizes 2012SkyPark: A Huge Rooftop, Steel Structure
Spanning Three High-rise Towers
Prize winner: Yasuhisa Miwa, JFE Engineering Corporation

Outline of SkyPark

As its name implies, SkyPark is an aerialpark constructed atop three high-rise towers
in Singapore. It measures 340 m in total
length and 40 m in width. As a newlandmark, SkyPark celebrated its grandopening in June 2010 and now stands out
among the various facilities operated by
Marina Bay Sands Pte Ltd., an integrated
resort company in Singapore (Photo 1).
A joint venture between JFE Engineering
C o r p o r a t i o n o f J a p a n a n d Yo n g n a mEngineering & Construction Pte Ltd. ofSingapore was awarded the contract in April
2008 to construct the steelwork for SkyPark.
The joint venture immediately commenced adetailed design and erection plan and in July2009 started the on-site work to complete theerection of an 8,000-ton steel structure in amere nine months.

Photo 1 SkyPark: A new landmark in Singapore

bridges and the cantilevered structure on
Tower 3 were pre-assembled into large
segments at the ground level in the side of thetower and lifted by means of a heavy-duty
strand jack assembled on a gantry frame
installed atop the tower. The large segments
thus assembled numbered 3 each for the main
girders of the two tower-connecting bridges, 2
for the two main girders of the box girder on
Tower 3, and 6 for cantilevered structure. A
total of 14 large segments, weighing 4,000
tons in total, were lifted and erected during
the three months from October 1, 2009 to
December 29, 2009. The segments were liftedto the target height of 200 m. Each segment
was lifted at a rate of 15 m/hour, over a
15-hour period.

Safety Measures

Because the construction work for SkyPark
routinely took place at heights surpassing
200 m as well as ground with other trades,
unprecedented care was taken to securemaximum worker safety. Practicallyspeaking, utmost efforts were thoroughly
and repeatedly made to spread over a large
working group, including 450 workers and
70 staff during the busiest period, that all
workers and staff wear a full harness toprevent falling and carry lanyards toprevent the dropping of tools. (Refer to
Photo 4)◆ ◆ ◆A noteworthy accomplishment in theconstruction of SkyPark is the completionof such a huge project, involving difficult
construction work, without serious
accidents over one million of working
hours of labor. This is largely attributable
to the united and highly vigorous effort by
local enterprise staff, locally recruitedengineers and the Japanese staff, efforts
that transcended culture and language, to■successfully complete the project.

Photo 2 Heavy lifting of steel truss bridge segment

Structure of SkyPark

SkyPark is composed of two steel truss
bridges connecting the three hotel towers(Towers 1, 2 and 3), a steel box girder
bridge extending to form 67.7m-longcantilevered structure on Tower 3, and twosteel-frame structures atop on Towers 2 and 3
to make an integrated structure.
Steelwork Fabrication and Erection

Steel structural members were fabricated by
Yongnam Engineering & Construction, a
local fabricator, and transported to theconstruction site.
In erecting the steel-frame structures on
Towers 1 and 2, the structural members werelifted one by one using the tower crane toplace them at the specified positions. (Refer
to Photos 2 and 3)
Structural members for the box girder
bridge on Tower 3, the two tower-connecting
1 Steel Construction Today & Tomorrow April 2013

Photo 3 Heavy steel segments were lifted tothe target height of 200 m.

Photo 4 A huge project was completed without
serious accidents over one million ofworking hours of labor.

Amagasaki Research and Development
Center—Employing 1,000 N-grade SteelPrize winners: Nikken Sekkei Ltd., Shimizu Corporation, Katayama Stratech Corporation and Sumitomo
Metal Industries, Ltd. (now Nippon Steel & Sumitomo Metal Corporation)

Sumitomo Metal Industries, Ltd. (now Nippon
Steel & Sumitomo Metal Corporation) has
developed 1,000 N-grade high-strength steel(tensile strength: 950 N/mm2), which is rated
as the world’s highest grade of steel. The firstpractical application of this steel was in theconstruction of the main building of thecompany’s Comprehensive Research andDevelopment Center (currently the Amagasaki
Research and Development Center of Nippon
Steel & Sumitomo Metal). (See Photo 1)
1,000 N-grade steel was developed by ajoint R&D consortium composed of Sumitomo
Metal, Osaka University, the Kyoto Institute ofTechnology, Katayama Stratech Corporation
and Nikken Sekkei Ltd. The cooperative R&D
was conducted from 2003 to 2010 and covered
not only development of the steel itself andrelated welding materials but also welding
conditions, such as heat input, preheating andpost-heating.

Photo 2 Steel framing installation

Photo 3 Column baseFig. 1 Structural Frame

1,000 N-grade steel column
Photo 1 Appearance of the building

The building offers the following threemajor structural features:• The response-control structures areconcentrated in the first story and arecomposed of 1,000 N-grade steel columns
and response-control braces (Fig. 1). Mostof seismic energy of an earthquake isabsorbed by the response-control braces

Fig. 2 Details of
Column Base
1FL
Crest offoundation

Photo 4 Interior view of laboratory room

installed in the first story, and thus theframes of the second and higher stories
remain in an elastic state during
large-scale earthquakes. In order that
1,000 N-grade steel columns remain in anelastic state during seismic motion that
surpasses assumed levels, the base ofeach column is fitted with sphericalsupports and short brackets to provide a
trigger mechanism that prevents thecolumns from yielding (Fig. 2, Photos 2
and 3).
• A wide working space, 133 m × 23 m, isprovided so that the laboratory can
flexibly adjust to future changes in
research themes and research organization(Photo 4).
• A double-skin structure is adopted on theeast side to promote energy savings,
and air-conditioning andlighting systems
have been adopted
that take into
account theo p e r a t i n genvironment of the
Response-control bracelaboratory rooms.
When the building is viewed from theShear panel
outside, the steel column-beam framing
employingthat is assembled in a lattice shape is
low-yield
visible through the glass, and at the
point steel
first-story entrance, visitors can directly(SLY225)
view the 1,000 N-grade steel columns andthe response-control braces concentrated on
the first story. These two structural systems
account for the notable features of the■building’s appearance.
April 2013 Steel Construction Today & Tomorrow 2

Technological Development ofCountermeasures against Long-period,
Long-duration Seismic Motion in Existing
High-rise Buildings
Prize winners: Osamu Hosozawa, Yuichi Kimura, Kenji Suda, Chiaki Yoshimura and Hideshi Aono,
Taisei Corporation
It is forecasted that Tokai, Tonankai, Nankai
and other great earthquakes will occur in thenear future in Japan. In this regard, there isconcern that long-period, long-duration seismic motions occurring during these earthquakes will be transmitted from the epicenterto far reaching areas while retaining a greatamount of energy. In large urban areas, there
are many high-rise buildings and some ofthese existing buildings were designed without consideration of countermeasure against
long-period seismic motions. Should thesebuildings be subjected to long-period seismic
motions, there is apprehension that large
oscillations will continue for a long time andthat these oscillations will damage not only
building structures but also non-structuralmembers and equipment.
As a measure to treat long-period seismic
motions occurring in existing high-rise buildings, it is effective to install response-control
dampers so as to add damping capacity andto thereby reduce maximum deformation andlateral oscillation. However, the installationof dampers on existing buildings poses one

problem: the reaction force of the dampers
acts on the existing framing (columns,
beams, foundations etc) which, as a result,requires reinforcement.
The countermeasure technology that wehave developed for long-period, longduration seismic motions in existing highrise buildings adequately meets this problem. Specifically, in applying this technology, deformation-dependent oil dampers are
adopted to reduce damping capacity in thevicinity of maximum deformation, thereby
allowing the installation of dampers without
reinforcing the existing framing. Further, acrimping method has been developed for

attachment of the dampers that uses PC steel
bars and does not require on-site welding,which has facilitated damper installation workon target buildings while in use. (Refer to Fig.
1 and Photo 1)
This technology was applied to the Shinjuku Center Building as a countermeasureagainst long-period seismic motions (Photo 2).
As a result, during the Great East Japan Earthquake of March 2011, this building did not
suffer any notable seismic damage thanks to
the response-reduction effect brought about by
the use of deformation-dependent oil dampers
and was able to continue business operations■
without interruption.

Fig. 1 Installation Position for Oil Dampers
Deformation-dependent oil damper(12 dampers/floor, a total of 288 dampers)

39th fl.

28th fl.
26th fl.

15th fl.
Standard floor framing plan

Photo 1 Installation of oil dampers
3 Steel Construction Today & Tomorrow April 2013

Photo 2 Shinjuku Center Building

Framing elevation

Tokyo Gate Bridge: Truss-Box Composite
Structure
Prize winner: Ken Fukunishi, Tokyo Port Office, Kanto Regional Development Bureau, Ministry of Land,
Infrastructure, Transport and Tourism

The Tokyo Port coastal highway project wasplanned for three reasons: to alleviate traffic
congestion in the area surrounding the Port ofTokyo that resulted from increased cargocontainer activity, to secure smooth logistics
and to reduce logistical costs. The Tokyo
Gate Bridge is a 2,618 m-long steel bridgethat constitutes one segment of the highway(Photo 1).
Being located near Tokyo International
Airport (Haneda), airspace regulations of 98.1
m is settled. Further, because the bridge spansthe east fairway of the Port of Tokyo, it had
to provide unobstructed passage space of 300
m in width and 54.6 m in height above waterlevel. Accordingly, a truss bridge was selected
because a suspension bridge or a cable-stayed
bridge requiring main towers would be
untenable.

Photo 2 En-bloc installation of the 6,800-ton
substructure assembled on-land

reduction in the total weight of the steel used
but also for the efficient construction ofbridges built under restrictive natural
conditions and requiring narrower welds inthe construction. Because of these, BHS
products were extensively used.
● Rationalized Design of the Steel SlabFraming and Fatigue Countermeasures for the Steel Slabs: Having

Photo 1 Truss-box composite structure Tokyo
Gate Bridge

Design of the Tokyo Gate Bridge

Construction of the bridge rested on design workthat had to hurdle a variety of restricting
conditions, reduce construction costs, create goodlandscaping and suppress maintenance costs. To
meet these requirements, it was necessary todevelop and adopt new technology, collect bridge
damage examples and devise
damage-improvement measures. Some
representative examples of these efforts follow:● Reduction of Steel Weight by Use of
BHS Members: For truss bridges in which

the dead load accounts for most of a bridge’s
weight, it is accepted that construction costs
can be lowered by reducing the bridge weight
to a minimum. Because BHS (bridge
high-performance steel) products havegreater strength than conventional steel
products, their use allows not only for a

conducted studies of truss frame structuresthat could reduce superstructure
deadweight and rationally distribute live
loads, a composite truss frame of the box
girder type was selected. In order toprevent the concentration of stress causedby cyclic loading on the steel slab, thetrough rib configuration was improved to
produce a steel slab with high fatigue
strength.
● Rationalized Panel Point and Fullsection Welding: The adoption of rigid

joining by means of full-section welding oftruss panel point, not by pin joining,eliminates the need for splice plates and bolts,
which, in turn, produces a structure that is
corrosion resistant and cheaper inmaintenance cost.

a seismic-isolation rubber bearing thatabsorbs the horizontal load occurring during
an earthquake, and a load supporting platethat constantly bears the vertical load andslides in conformity with the behavior of theseismic-isolation rubber bearing during anearthquake.
● Bridge Monitoring System: Because
full attention has been given to bridge
maintenance since the start of construction, amonitoring system was introduced thatobserves the consistency between the design
and the bridge’s current state, registers thecharacteristic properties of the live load andmeasures the bridge’s accumulated damage.
Specifically, strain gauges, displacementgauges and accelerographs were applied toquantitatively observe the constant numericalvalues and to obtain data conducive toworking out future maintenance plans.
Construction of Tokyo Gate Bridge

Construction of the foundation structure
began in October 2003. While the foundationand substructure work was carried out at theoffshore site, manufacture of thesuperstructure was conducted at a land-based
plant. In September 2008, the lower trusses(6,800 tons) that had been assembled on-land
were installed en-bloc. The trusses were liftedin tandem onto the bridge piers by means of
three 4,000-ton crane ships-the largest scale
operation of its kind ever seen in Japan(Photo 2).
The superstructure was then installed spanby span, until February 2011 when the center
span, the last piece of the operation, wasinstalled. After fence work and paving, thebridge was put into service on February 12,■
2012. (Refer to Photo 3)● Bearings with Seismic-isolation
Structure: In order to support the 80,000

kN of bearing’s vertical reaction force andto provide seismic resistance during anearthquake, function-separated, sliding
seismic-isolation bearings were adopted.
The load support function and the seismic
resistance function of the bearings wereseparated, and two devices were installed:

Photo 3 Illuminated Tokyo Gate Bridge, awonderful nighttime view in the Port of Tokyo

April 2013 Steel Construction Today & Tomorrow 4

JSSC Thesis Prizes 2012
Study of the Fracture Behavior of Electro-slag Welds in Beam-Column
Connection Framing Models
Prize winners:YongHun Song, Kawagishi Bridge Works Co., Ltd.; Takumi Ishii and Hiroumi Shimokawa,
JFE Steel Corporation; Takahiko Suzuki and Yoichi Kayamori, Nippon Steel & Sumitomo Metal Corporation;
Yukihiro Harada, Chiba University; and Koji Morita, Tokyo Denki University
YongHun Song
2006: Entered Kawagishi
Bridge Works Co., Ltd.
2011: Finished the Graduate
School & Faculty ofEngineering,
Chiba University: Obtained D.Eng.

Along with the increasing height of building
structures, there is a growing demand for weld
built-up box-section columns. In the manufactureof these columns, electro-slag welding (ESW) is
used for the welded joints between the column
skin plates and the interior diaphragms. While
ESW is a highly efficient welding method, it
requires a large heat input. Accordingly, fracture
Fig. 1 Example ofFracture Modes

toughness in the heat-affected zone of ESW
welds is lower than that in the base metal,
thereby causing concern that brittle fracture
might occur (Fig. 1). Furthermore, because theadopted weld detail generates slits between thecolumn skin plates and backing plates, the stressconcentration is severely high at tips of the slits(Fig. 2), and thus it is difficult for the weld detailto adequately prevent the occurrence of brittle
fracture.
In this paper, in order to clarify the fracture
toughness of the weld bond, the heat-affectedzone and the weld metal of ESW welds, several
factors were considered with regard to thewelding quality (penetration depth, misalignment)

Fig. 2 Example of Principal
Stress Distribution
near the Slip Tip

and design (tensile axial force of column skinplate). How these factors affect brittle fracture
was introduced by means of experiments andanalysis. In addition, state-of-the-art
investigations were conducted to correlate thefracture toughness (resistance) with the fracture
toughness index (requirement) based on theexperimental and analytical results. Morespecifically, focusing on the critical maximum
principal stress, the following two correlations,the critical maximum principal stress obtained byfinite element analysis versus fracture toughness(Fig. 3), and the connection strength of the ESW
joints obtained by experiments versus fracture■
toughness (Fig. 4), were found.

Fig. 3 Correlation between
Principal Stress andMaterial Toughness

Fig. 4 Correlation between
Connection Strength andMaterial Toughness

Plastic Deformation Capacity of Cold-formed Circular Steel Tube Columns
Subjected to Cyclic Loading
Prize winner: Nobuyuki Yasui, Professor, Nagasaki Institute of Applied Science
Nobuyuki Yasui
1993: Finished
School/Graduate
School of Engineering,Osaka University
1993: Entered Kawatetsu
Metal Products & Engineering Inc.
2011: Professor, Nagasaki Institute ofApplied Science

The main object of this study is to clarify
the plastic deformation capacity of circular
steel tube columns, the strength of which issteadily reduced due to the accumulation of
local buckling deformation caused by cyclicloading. For that purpose, numericalanalysis was conducted on cold-formed
5 Steel Construction Today & Tomorrow April 2013

circular steel tube columns subjected tocyclic loading with specified amplitudes
under specified axial force conditions.
The analysis focused on circular steel
tube columns subjected to cyclic horizontal
deformation with specified amplitudes under
specified axial forces P (Fig. 1), for which
an asymmetrical local buckling analyticalmodel proposed by the author w a s
adopted. The relation between themember end moment M and the member
drift angle θ shown in Fig. 2 was obtained
from the analytical results, and Σθ pM , theaccumulated plastic drift angle up to thepoint where M fell to the full plastic

moment M pc that takes into account theaxial force, was set as the plastic
deformation capacity in the current study.
Fig. 3 shows an example of the relation
between ΣθpM, the accumulated plastic drift
angle, and D/t, the width to plate thickness
ratio. Because the relation between D/t andΣθ pM showed a favorable correlation, therelational expression of D/t and ΣθpM thatassesses the plastic deformation capacity
was found by regressing the analyticalresults.
The red circle in Fig. 3 shows the resultsof the experiment that was conducted toconfirm the validity of the regression

curve. Because the plotted points of theexperimental results are distributed in thevicinity of the regression c u r v e , i t c a n
be said that the plastic deformation

capacity of circular steel tube columns canbe adequately predicted using the relation

between D/t and Σθ pM as proposed in the■current study.
Fig. 3 Relation between ΣθpM
and D/tFig. 2 Accumulated Plastic
Deformation Angle

Axial force ratio

Fig. 1 Analytical Targets
Circularsteel tube
columnModeling=400 mm

Amplitude

Local
bucklingfield

Elasto-plastic
hinge
Elasto-plasticstraight line
memberBending
shear bar

Experiment

Replacedbuckling
element

Local
buckling
field

Effect of Weld Shape on the Occurrence of Ductile Cracks in Welds
Subjected to Bending during Earthquakes, and the Suppression of Ductile
Cracks by Means of Weld Toe Finishing
Prize winners: Hiroshi Tamura, Assistant Prof., Tohoku University; Eiichi Sasaki, Associate Prof.,
Tokyo Institute of Technology; Songdong Kim; Hitoshi Yamada, Prof., Yokohama National University;and Hiroshi Katsuchi, Prof., Yokohama National University(Values in the figure indicate the weld toe radiusin mm)

0.9

1-

Depth of tcrack (mm)0.8

Fig. 1 Test Specimen

1-

0.7

1-

0.6

0.2

25

0m

m

50

2-

0.40

2.98
0.66

0.58

1.68 2.36
2.52 3.34

0.50

0.1
0

2-

0.47

0.4
0.3

2-

0.46

0.5

0.80
2

4

6

8

2-

Cycles of loadingmm

Fig. 3 Analytically-obtained Crack Depth Distribution at Crack Initiation Point
1.8
1.6
1.4

Same order with T1
T2

1.2
1.0
0.8

T1

0.6

0.4 Weld toe with the toe radius 0.4, 0.6,
0.8, 1.0, 2.0, 3.0 mm
0.2
0.0
0.0

0.2
0.4
0.6
0.8
Depth of crack (mm)(a) Stress triaxiality T1 and T2

1.0

Equivalent plastic strain

In steel structures built using many welds,
remarkable stress triaxiality and strain
concentration occur due to weld shapediscontinuity, thereby allowing the possible
initiation of ductile cracking in weld toes
because of bending deformation in welds during
earthquakes. In such cases, there is the danger
that ductile fractures will serve as the starting
point of brittle fractures (brittle fractures during
earthquakes). This type of brittle fracture
occurred in many steel buildings during theNorthridge and Great Hanshin Earthquakes,
causing societal concern about steel-structure
construction.
In the current study, in order to verify theeffect of weld shape on limiting ductile crack
initiation in weld toes, cyclic loading tests andFEM analysis were conducted on cruciform
weld joint test specimens prepared bysimulating the welds of actual steel structures.
As a result, differences were experimentallyshown regarding the limiting of ductile crack
initiation under cyclic loading conditions
depending on various weld shapes. Further, as

Fig. 2 Experimentally-obtained Crack
Initiation and Development

100 mm2008: Graduated from
School of Engineering,
Yokohama National
University
2012: Finished Doctoral
Course, Graduate School of Engineering,
Yokohama National University

a result of FEM analysis of the effect of weld shapeconfirmed in the tests, it became clear that, among leg
ratio, toe radius and toe finishing and their respective
effect on the reduction of base metal thickness, theeffect of toe radius was particularly notable. From theabove results, it is considered that the use of toe
finishing to increase toe radius is effective insuppressing the development of ductile cracks■
occurring in weld toes.

Stress triaxiality

Hiroshi Tamura

50%
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
0.0

0.4
0.6

0.8
1.0

2.0
3.0
0.2
0.4
0.6
0.8
Depth of crack (mm)1.0(b) Equivalent plastic strain
April 2013 Steel Construction Today & Tomorrow 6

Special Feature: Advanced Super High-rise Building Technologies in Japan

Seismic Design of High-rise Buildings

by Akira Wada, Professor Emeritus, Tokyo Institute of Technology; Chairman of CTBUH Japanese Group

Development of Seismic Engineering inJapan

In 1924, one year after the Great Kanto
Earthquake that devastated Tokyo, Professor
Toshikata Sano (1880-1956) added to the
Urban Building Law a new requirement: thestatic horizontal seismic factor should be set
as 0.1 or more. Ten years later, Professor Ryo
Tanabashi (1907-1974) published an article in
July 1934 stating that the seismic resistanceof a structure cannot be adequately assessedsimply by providing ample strength against astatic horizontal force; he contended that theseismic impact should be expressed using theenergy squared by the maximum ground
velocity and that the resisting capacity of astructure should be assessed using the strainenergy absorbed by the structure itself. In
March of the same year, he suggested that
research should be started on theconstruction, even in earthquake-prone Japan,of super high-rise buildings like those seen in
New York.
I n t h e p o s t w a r p e r iod, Professor
Tanabashi insisted through his article
published in April 1963 that high-risebuilding should be possible in Japan in lightof the following examples: given that seismic
motion works on small and large structureswith identical amplitudes, a flower vasemight fall over in an earthquake, but a large
high-rise building would not, even if bothobjects were proportionally identical. In otherwords, contrary to small boats, large ships areresistant to capsizing in rough seas.
Around the same time, Professor Kiyoshi
Muto (1903-1989) promoted research on ahigh-rise building for the Tokyo Station.
While his effort in this case was not
rewarded, the Hotel New Otani wascompleted in Tokyo in 1964 with a buildingheight surpassing 45 meters. In 1968, theMitsui-Kasumigaseki Building designed by
Prof. Muto, was completed as Japan’s firsthigh-rise building to surpass 100 meters inheight. On every story of the building frame,
precast concrete walls with many verticalslits were incorporated to maintain theirinitial structural stiffness while absorbinge n e rg y d u r i n g a s t r o n g e a r t h q u a k e .
Accordingly, it can be said that the conceptof passive-controlled structures was alreadybeing applied at the initial stage of high-risebuilding in Japan.

7 Steel Construction Today & Tomorrow April 2013

Introduction of Advanced Seismic Design

Entering the 1970s, most high-rise buildings
were constructed using a seismic design
method that relied on the plastic rotation
capacity of steel-frame beam ends to provide
energy absorption. However, several structuraldesigners believed such designs would leavethese buildings with residual deformation inframes subjected to large plastic deformation,
thereby making restoration difficult. In
response to this, the concept ofdamage-controlled design began to grow (referto the figure below). The Northridge
Earthquake of January 1994 and the Great
Hanshin Earthquake of January 1995 caused
fracture phenomena in many steel-structurebeam-ends, resulting in considerable concern
about the feasibility of restoring damagedbuildings.
In Japan, following implementation of the
New Seismic Design Codes in June 1981,
extensive research has been conducted onseismic-isolation structures. In 1995 aseismic-isolation structure was put into
practical use that adopted energy-absorption
members such as steel and lead dampers alongwith employing laminated rubber bearings aselastic supporting members. Since then,another concept has been increasingly applied
whereby the beam-column frames of high-risebuildings bear vertical loads in a manner
similar to the laminated rubber bearings inseismic-isolation structures. This design
produces mainly elastic behavior during anearthquake so that the seismic energy isabsorbed by the energy absorbing members
incorporated in the framing of each floor.
Enhanced Seismic Resistanceconcrete-filled tubular columns manufactured
by filling square or circular steel tubes withconcrete.
In addition, remarkable progress incomputer-aided structural analysis technology
makes it possible to use dynamic response
analysis that can accurately treat the dynamic
behavior of columns, beams, shear walls andvarious dampers. This, in turn, has resulted in
the construction of high-rise buildings withcomplex framing and super high-rise buildings
with heights reaching 300 meters.
The Great East Japan Earthquake that
occurred on March 31, 2011, produced large
amplitudes and long-duration vibrations inhigh-rise buildings not only in Sendai near the
epicenter but also in Tokyo, Osaka andNagoya. Earthquake ground motion isrecorded by means of acceleration, andresponse analysis for seismic design isconducted by inputting the recorded groundmotion. However, because the acceleration of
the long-period component included in groundmotion is much lower than that of theshort-period component, certain problems haveemerged vis-à-vis the occurrence of
unexpected large vibrations in buildings
located far from an epicenter. These large
vibrations are due to the following two
reasons: 1) the earthquake ground motion is
not accurately included in the acceleration
records applied in conventional design; and 2)
Earthquake ground motion is commonly
applied for 30 seconds duration in the response
calculation. However, tall structures withlimited damping capacity that are subjected tolong-term ground motion with a period of 4
seconds or more exhibit synchronized large
vibrations after this 30 seconds until 600
seconds. To cope with this problem, existinghigh-rise buildings have been retrofitted with■seismic energy absorption members.

In addition to the seismic designs mentioned
above, the seismic safety of high-rise steel
structures is steadily being enhanced due tofollowing factors: higher strengthand sufficient ductility of steel Damage-controlled Structurematerials, the provision of upperand lower limits for yieldstresses, progress in welding
technology and the adoption of
haunches to prevent theplasticization of beam-end welds.
Another contributing factor is theutilization of column members
Primary structurewith stiffness and strength that Building structure(to support
are made possible by the use ofgravity weight)

Seismic member(to absorb earthquake energy)

Wind-resistant
Design of High-rise Buildings

by Yukio Tamura, Professor, Tokyo Polytechnic University; Member of CTBUH Japanese Group

Points to Note in Wind-resistant Designof High-rise Buildings in Japan

In Japan, very strong seismic excitations suchas The 2011 Off The Pacific Coast Tohoku
earthquake on March 11, 2011 (magnitude
9.0, maximum recorded ground acceleration
2,933 cm/s2) have to be considered. It is also
true that Japan has very strong typhoons, e.g.
Typhoon Maemi passed over the Miyakojima
Island on September 10 and 11, 2003, and a
3s gust wind speed exceeding 90 m/s wasrecorded (Cao et al., 2009).
For seismic actions, buildings should belightweight and flexible, but for wind actions,buildings should be massive and rigid. Thus,
opposite design criteria apply for buildings
for seismic and wind actions, and very highlevels of both seismic actions and wind
actions have to be considered in Japan.
In general, the dominant external design
load is seismic load for the majority ofhigh-rise buildings, say lower that 200 m
high. Therefore, they are basically lightweight and flexible, thus making themvulnerable to winds. Furthermore, habitability
to building vibrations induced by daily winds
is inevitably an important issue in Japan.
Since the early ‘70s, unique and significant
development has been made in Japan not
only for structural performance against
external actions, but also for evaluation of

habitability to building vibrations and forwind environmental assessment. For
various wind resistant design aspects,
suppression of wind-induced responses is
an important issue.
Comprehensive Study on Aerodynamic
Characteristics of High-rise Buildings
with Unconventional Configurations

For high-rise or super-high-rise buildings,
crosswind response due to periodic Karmanvortex shedding is predominant overalong-wind or torsional responses.
Therefore, aerodynamic means to prevent
formation of Karman vortices, to reduce
their intensity and periodicity, and tominimize spatial correlation of shed vortices
along the vertical axis, are useful. Recently,
many high-rise and super-high-rise buildings
with unconventional configurations, such as
Burj Khaliha and Shanghai Tower, havebeen constructed around the world. One
reason for their curious and complicatedconfigurations is the advantageous
aerodynamic characteristics, especially forthe crosswind component.
The author has been collaborating with
Takenaka Corporation, Kajima Corporation,
Nikken Sekkei, and Nihon Sekkei, tocomprehensively investigate aerodynamic
characteristics of super-high-rise building

models with various unconventional
configurations. This work has been
financially supported by the Ministry ofLand, Infrastructure, Transport and Tourism(2008FY-2009FY, MLIT) and Japan Scienceand Technology Agency (2010FY-2012FY,
JST). Thirty-seven models including squaremodels with sharp edges, with corner cut,
and with corner chamfer; models withvarious twist angles (helical models), withsetbacks, with taper, and with various
openings; and triangular models including
clover type, composite types, and so on. The
height and the volume were set at 400 m
and 106 m2, respectively, for all models.
According to our study, the aerodynamic
characteristics of triangular models and aclover type model, which have recentlyb e c o m e p o p u l a r f o r s u p e r- h i g h - r i s ebuildings, are not necessarily good. Fig. 1
shows the maximum along-wind andcrosswind fluctuating wind force coefficientsfor 28 models, except for triangular andsome other models. “Square Model” isshown on the left end of Fig.1. The
efficiency of corner modifications, twistingangle for helical models, taper, setback, andcombinations of these configurations areclearly demonstrated. Combination effects
are especially significant for reducing■
crosswind forces.

0.2
Crosswind
0.15
0.1
Along-wind

C. Cut + Setback

Setback + Rotation

C. Cut + Helical

C. Cut + Helical + Taper

5/24 oblique-opening

11/24 oblique-opening

11/24 cross-opening

2/24 oblique-opening

5/24 cross-opening

2/24 cross-opening

360° helical

180° helical Rectangular

270° helical

90° helical

180° helical

BulgedSetback

Inversely tapered

4 tapered

2 taperedTiltedWindingCorner cut

Corner Chamfered

Elliptic

Circular0

Rectangular

0.05
SquareFluctuating wind force coefficientFig. 1 Comparisons of Fluctuating Wind Force Coefficients for 28 Models

April 2013 Steel Construction Today & Tomorrow 8

Latest High-rise ProjectSony City Osaki

─Transpiration Louvers and Variable Seismic-isolated Structures─
by Toshihiko Kohno, Nikken Sekkei Ltd.

ambient peripheral temperatures werereduced almost as forecasted bysimulations conducted in the design stage
using building information modeling(BIM). The bio skin is supported by atension structure using stainless steel rods.
The specific tension introduced by meansof nut rotations is confirmed throughvibration measurement.

and five void cores have been left empty tomeet the need for future changes infunction. Space is provided below groundfor a 3,400-ton heat storage tank and for
sodium–sulfur (NAS) batteries to be usedin emergencies and for energy savings.
Fig. 1 Floor Plan and Section
24.3 m 7.2 m

In order to treat the emerging problem
posed by “urban heat islands,” the Sony
City Osaki project was based on the ideaof “constructing a building as if planting
a tree.” In addition, the building plan wasstarted with an awareness of thefollowing question: What kind ofadvanced environmental measures can beu s e d b y s u c h a l a rg e - s c a l e b u i l d i n g
project that generates a large
environmental burden?
Full Consideration of Environmental Issues

In order to allow the wind to blow
through, the building has the shape of aflat vertical plane (Photo 1) and islandscaped with rich greenery in thesurrounding area. It also makes trial use of
a newly developed “bio skin” systeminstalled on the east side of the building.
In the system, rainwater is circulated
inside transpiration terra-cotta louvers thatallow the rainwater to evaporate, whichtakes heat from the air. In addition, thewind blows through the building lot,
thereby cooling the surrounding area ofthe building (Photo 2). The power required
to circulate the rainwater is provided bysolar panels.
Actual measurements confirm that

138 m

131 m

17 m

Isolation
floor

Photo 2 “Bio skin” system in which rainwater iscirculated inside transpiration terra-cotta
louvers to cool the surrounding area ofthe building

Outline of Building Plan

Photo 1 Full view of Sony City Osaki
9 Steel Construction Today & Tomorrow April 2013

The flat vertical plane shape of thebuilding was an inevitable choice from anenvironmental perspective. Thus, thebuilding is designed as a single core
structure in which the 24 m × 130 m officefloors are located on the east side and theEV, stairs, restrooms and other equipment
are placed on the west side. The
workspaces have an area of about 3,000 m2
each and are column-free due to the use of
external framing. Balconies around thebuilding periphery help to improve
maintenance performance and fireevacuation safety. (Refer to Fig. 1 andPhoto 3)
The facilities for various functions along
the west-side core are positioned as needed,

Photo 3 Spacious column-free workplace

Seismic-isolation System

A major structural theme of the current
project was to secure improved seismic
resistance by adopting seismic-isolation
devices appropriate for an office building inthe shape of a thin vertical plane having aheight over 130 m. (Photo 4) The seismic
resistance of the building during greatearthquakes is twice that of non-seismicisolation-type buildings (an approximate
inter drift angle of 1/200 and a floor
response acceleration of 250 cm/s 2 orlower). The adopted variableseismic-isolation system is composed ofnatural rubber-laminated isolators (highbearing specifications of 1,100~1,500 φmm), oil dampers and steel dampers.
Because of the steel-structure flat verticalshape of the building, the anticipated windload generated by a typhoon would be larger
than the seismic load reduced by theseismic-isolation system. The oil dampers
installed on the narrow side of the buildingthat is subject to large wind loads are fittedwith a locking mechanism to control oil
movement using electromagnetic valves(Photo 5). The oil dampers themselves arecontrolled using anemometers,
accelerometers and displacement gauges tomitigate the vibration of theseismic-isolation layer and the accumulated
plasticity of the steel dampers during strong
winds. Seismic motion-precedence control isadopted so that the locking system isreleased when a certain level of seismic
motion is detected. The combined use of oiland steel dampers is effective in securing
structural rigidity when oil movement islocked and is a solution that resulted fromthe pursuit of low cost and highperformance.
The beams on the west-side core facecantilever more than 7 m and reduce theaxial force of the intermediate columns so
as not to overstress the 1,500 φ mm
isolators supporting the intermediate
column.
The top of the cantilevered beams thatare greater than 7 m in length are connectedby studs to a viscous material so as toreduce vertical vibration and relative
displacement. In addition, other vibration
countermeasures have been taken at various
levels: improvement of damping capacity by
installing V-shaped visco-elastic memberson the short vertical face (Photo 6) andmicro-vibration countermeasures on the fifth
floor.
◆ ◆ ◆The Sony City Osaki project employs themost advanced approaches for high-risebuilding construction that have ever been

Photo 6 V-shaped visco-elastic damper tocontrol vibrations

proposed and put into practicaluse-including a seismic-isolation systemof variable mechanisms and a newenvironmental method for cooling abuilding’s immediate vicinity. (Refer to■
Photos 7~9)
All photos of Sony City Osaki:
Harunori Noda (Gankosha)

Photo 4 Construction of the seismic-isolation floor

Photo 5 Oil damper fitted with a locking
mechanism to control oil movement

Photos 7~9 Sony City Osaki project was based on the idea of “constructing a building as if planting atree” in order to treat the emerging “urban heat island” problem.
April 2013 Steel Construction Today & Tomorrow 10

Latest High-rise Project

ABENO HARUKAS─Performance-based Design of Japan’s Tallest Building─by Kiyoaki Hirakawa, Takenaka Corporation

This article introduces specific examples
of how performance-based design wasincorporated in the overall structuraldesign of ABENO HARUKAS, thetallest building (300 m) in Japan,
consisting of a department store, offices
and a hotel (Photo 1).

Fig. 1 List of Technologies Adopted

ATDM
Guide damper
Seismic-resistantbrace

Outline of Structural Plan

Five major issues had to be solved in the
structural design of the building.
● Constructing a frame capable of handling high axial forces● Designing a framing plan to suppress
deformation● Responsiveness to foreseeable largescale seismic shocks● Securing acceptable comfort levels instrong winds● Introduction of technology that considers construction efficiency
The structural plan that was devised toresolve these issues are outlined below:
The truss floors are located between the
low-rise and medium-rise sections andbetween the medium-rise and high-rise
sections; and, further, braces are positioned
in the mid-story office spaces so as toobtain a reverse bending effect (Fig. 1).
In the low-rise section, viscous oil
dampers and rotational friction dampers
are arrayed in the four corners. In thevicinity of the center core of the mediumrise section, corrugated steel plate seismic
walls are placed along the X direction andseismic steel-frame braces in the Y direction. In the high-rise section, a rigid frame
is adopted in the X direction; and in the Y
direction, seismic steel-frame braces arelocated inside the boundary walls of thehotel rooms.

Hotel

Middle truss

Outrigger

OfficeOutrigger

Museum

Bottomtruss
Damper
Department
store

CFT column

PhotoLatestconstruction
situation situation
Photo1 (north-west
1 Latest
construction
view)(north-west view)

The building’s seismic design incorporated
three categories of seismic shock input, asshown in Table 1. The first category displays
the values for legally required waves and conventionally adopted standard waves; thevalues of the second category, representing the
maximum levels of seismic shock (used forseismic safety margin analysis level), areobtained by multiplying Level 2 seismic

Piled raftfoundationciated with the Tonankai and Nankai Earthquakes and the Uemachi Fault.
As shown by the seismic design criteria inshock waves by 1.5; and the third category,taking localized characteristics into consideration, displays the seismic shock waves asso-

Table 1 Input Seismic Motions for Design Purpose and Seismic Safety Margin Analysis
Level 1

Standard
wave

Diverse Types of Seismic Design

11 Steel Construction Today & Tomorrow April 2013

Observatory

Hat truss

Notification
wave

Regional
wave

Level 2

Seismic safetymargin analysis level
V max. A max.
(mm/s) (mm/s2)

V max.
(mm/s)

A max.
(mm/s2)V max.
(mm/s)

A max.
(mm/s2)

Elcentro 1940NS
TAFT1952EW

250
250

2,555
2,485

500
500

5,110
4,970

-

-

Hachinohe 1968NS
Notification wave A
Notification wave B
Notification wave C
Nankai Earthquake NS
Nankai Earthquake EW
Tonankai/Nankai Earthquakes NS
Tonankai/Nankai Earthquakes EW
Uemachi fault zone Case 1 NS
Uemachi fault zone Case 1 EW
Uemachi fault zone Case 2 NS
Uemachi fault zone Case 2 EW

250
76
109
83
-

1,669
552
471
497
-

500
379
613
383
210
275

3,338
2,517
1,929
2,098
863
987

528
817
560
-

3,244
2,919
2,604
-

-

-

-

-

268
419
329

1,213
1,067
3,485

-

-

-

-

813
291
456

4,107
2,317
3,269

Table 2 Design Criteria
Level 1

Level 2

Seismic safety margin
analysis level

Seismic motion• Rare• About 50 years ofrecurrence interval• Extremely rare
• About 500 years ofrecurrence interval

1.5 times stronger than
notification level 2

Target building performance

Continuously usable

Repairable

Repairable(Reinforceable)

10.00×10-3 rad

13.50×103 rad

Ductility factorof story

5.00×10-3 rad.
Allowable stress for
short-term loading,or less

1.0 or lower

2.0 or lower

Underground frame
and foundation

Allowable stress for
short-term loading,or less

Less thanultimate
strength

Underground frame:
Ductility factor of
members<4.0
Foundation/piles:
Ultimate strength or lower

Pile bearing
capacity

Allowable bearing
capacity for shortterm loading, or less

Allowable bearing
capacity for shortterm loading, or less

Ultimate bearing
capacity or lessStory drift angle
Superstructure

Substructure

Table 2, the criteria adopted for the current
building have been upgraded from the design
criteria used for structural members used inordinary high-rise buildings. Specifically,
these members do not allow plasticization in
response to Level 2 seismic movement, but in
response to earthquakes in the range wheredegrees of allowance are studied, plasticization of the girders and braces is allowed.
Application of New Structural
Technologies• CFT Columns Employing
High-strength Materials

In order to bear high axial forces,
concrete-filled steel tube (CFT) columns wereadopted that use both high-strength Fc150
concrete and 590 N/mm2-grade high-strength
steel. CFT column performance wasthoroughly confirmed by means of not only
structural performance confirmation tests but
also fire resistance tests and concrete filling
performance tests (Photo 2).

Photo 4 Corrugated steel plate wallFig. 3 Guide Damper

sprayed aluminum to improve the sliding
coefficient from 0.45 to 0.70 2) , thereby
reducing the labor required for joining andreducing the construction term.

ATDM

Fig. 2 Division-type diaphragmOil damper

Fig. 4 Location of ATDM

• Response-control Dampers

In the low-rise section of the building, both
highly velocity-dependent oil dampers andhighly deformation-dependent rotational
friction dampers were installed.
The rotational friction dampers (Photo 3)
have the advantage of being a simple
mechanism and using friction as the damping
force, thereby allowing the prescribed friction
force to be obtained by adjusting the pilingnumber of the pad without taking brace
rigidity into account.
In the medium-rise section, corrugated steel
plate walls are used in the walls of the EV
halls and resist the horizontal forces by
allowing shear yielding. They effectively
absorb seismic energy (Photo 4) .

In the high-rise section, a vertical truss
drops downward from the hat truss toward theatrium (Fig. 3) and oil dampers are installed
between the downward truss and the peripheral
framework, thereby reducing the inter-story
drift angle of the high-rise section by about
10%. An active tuned mass damper (ATMD)
is installed at the top of the building (Fig. 4).
The hat truss floor is equipped with massdampers, one each at the west and east ends ofthe building as shown in Fig. 4 for the purposeof improving the habitability of the hotel in■strong winds3).
References

Photo 2 Filling capacity confirmation test

• New Joining System

A division-type outer diaphragm system(Fig. 2)1) was adopted in consideration of
the concrete filling performance of CFT
columns and the work efficiency of the CFT
column manufacturing plant. In the joiningof girders to the CFT columns, a n e w
connection system was adopted that uses

Photo 3 Front view ofrotational
friction damper

1) S. Matsuo, K. Saburi, T. Tanaka and I. Inoue:
P a r t i a l F r a m i n g Te s t o n D i v i s i o n O u t e r
Diaphragm-type Square Steel Tube
Column-H-shape Beam Connection, Journal of
Structural and Construction Engineering,Architectural Institute of Japan, Feb. 2010
2) Sliding Coefficient and Relaxation Characteristics
of High-strength Bolt Friction Joint Using
Aluminum-sprayed Splice Plate, AIJ Journal ofTechnology and Design, Aug. 2009
3) Guidelines and Commentary on Livability
Assessment pertaining to Building Vibrations(2004), Architectural Institute of Japan
April 2013 Steel Construction Today & Tomorrow 12

Latest High-rise Project

ARK Hills Sengokuyama Mori Tower
─Advanced Safety and Building Technologies─

by Toru Tsuchihashi and Masaharu Yasuda, Mori Building Co., Ltd.;and Masayuki Yamanaka, Shokichi Gokan and Shuichi Otaka, Obayashi Corporation
The ARK Hills Sengokuyama Mori Tower
represents one element in the large-scale
Toranomon-Roppongi District Urban Development Project being promoted in the
Toranomon and Roppoingi areas of Tokyo.
The Tower development project covers
about 2.0 ha and was completed in August
2012. Surrounding the redevelopment area
are many embassies and hotels that anchor
the area’s role as an important internationaland cultural center in Tokyo.
The 47-story complex sits on relatively
high ground and consists of commercial
Photo: Toranomon-Roppongi Work Office

and residential sections (floors 1-24) and
an office section (floors 25-47). A separate
7-story residential building (seismicisolated structure) is planned for erection
on the south side of the complex. (Refer to
Photo 1 and Table 1)
Outline of Structural Type and Design

Rigid reinforced concrete framing was
adopted for the building’s structure. The
standard floor plan was 50.4 m × 50.4 m(7.2 m × 7 spans). For the high-rise officefloors, steel girder framing with a length of
2~3 spans was adopted to realize wide,
Fig. 1 Standard Floor Framing Plan for
Office Floors
Steel girdercolumn-free spaces (Fig. 1). In the centercore section, viscous response-control
walls and hysteresis response-control walls(brake dampers) were installed (Photo 2).
The main structural materials werehigh-strength concrete (Fc120 N/mm 2max.) and high-strength steel reinforcing
bars (σy685,785 N/mm 2). The foundation
type is of the spread foundation consistingof 4.5 m-thick mat slabs, and was installed
on a supporting layer of sandy soil (longperiod soil bearing strength: 100 t/m 2 ormore). The structural performance targetsof the building and the corresponding test
results are shown in Table 2.

RC frame

Photo 2 Viscous response-control wall andhysteresis response-control wall
(brake damper)

Precast Method• LRV Method

Brake damper

Viscous damper(Source : Obayashi Corporation)
Photo 1 Panoramic view of ARK Hills
Sengokuyama Mori Tower

Table 1 Building Outline
Use

Office, residence, retail,parking

Site area

15,367.75 m2

Total floor area

143,550.04 m2

Floors47 above ground,
4 under ground

Maximum height+206.69 m

Structure

Reinforced concrete(partly: steel)Seismic control structure

13 Steel Construction Today & Tomorrow April 2013

In the LRV (left right vertical installation
precast) method, connection-partial beam
precast members are adopted. The precast
members are of two types: beam-connection

Table 2 Structural Performance Targets and Corresponding Test Results
Level

Target value

Results
Direction Calculated value Generating floor Seismic wave
0°
90°

1/349
1/413

28F
26F

Taft-EW
Taft-EW

Drift angle

R<1/200

Ductility ratioµ<1

Drift angle

R<1/100

0°
90°

1/147
1/155

28F
14F

KOKUJI-HT
KOKUJI-KB

Ductility ratio

µ<2

0°
90°

0.73
0.76

9F
1F

KOKUJI-HT
EL Centro-NS

Level 1

Level 2

Yielding does not occur

Design seismic wave
Level 1;25kine, Level 2;50kine modified the configuration of maximum ground motion speed
KOKUJI- :Simulated ground motion waveform is created based on the spectrum defined in the Building Standards Law

integrated precast members Fig. 2 Overview of LRV Method and LRV-H Method(LR beams) in which theprimary mode of column
reinforcement is passthrough penetration holes
V-column
made using sheath pipes,
and precast columns (V colH-beamumns) in which mortar-filled
LR-beammechanical joints (sleevejoints) are built into thecolumn heads from which
Girder of thecolumn reinforcing bars proColumn of theprevious step
previous step
trude from the bottom andpass through the penetration
holes in the beams. Mortar
LRV Method
LRV-H Method
is used to fill in the joints
between precast members,(Source : Obayashi Corporation)
the main reinforcement penetration holes and the LR beam-V column run horizontally. A sleeve joint is installedjoints so that the respective members are near the end of the intersecting beams, andthe primary reinforcing bars extend to theintegrated into the framing structure. (Fig. 2
end of the precast beam on the opposite
and Photos 3~4)
side of the sandwiched column. The beam
Photo: Toranomon-Roppongi Work Officereinforcing bars pass through the beam
reinforcement penetration holes provided in
the column and are then inserted into thesleeve at the end of the beam end on theother side. (Fig. 2)

Hybrid Structure(Reinforced Concrete-Steel Beam
Structure)

In order to realize column-free spaces on
the office floors, steel girders were adopted
for the long-span sections, and a joining
method was adopted in which the steel
girders are wrapped with concrete (Fig. 3).
In the design stage, performance confirmation testing was conducted on the hybrid
structure, the results of which are reflectedin the design.
The yielding position of the beam wasset inside the steel framing, which allows
for the framing property to be tough evenafter yielding.

Brake Dampers

The brake dampers are structured like
automotive disc brakes. The vibrationenergy of the building is converted tofriction heat due to the damper’s sliding
under certain loads so that the responseand damage of the building are mitigated.
The brake damper system can be used
repeatedly and requires no need for main■
tenance. (Fig. 4)

Fig. 3 Partial Steel Girder-Reinforced Concrete Hybrid Structure
ColumnCast-in-place
concrete
PrecastconcreteSteelgirder
RC parts

an

sp
ng e
o
L am
fr

Assumed yield position

Steel girder(Source : Obayashi Corporation)

Fig. 4 Basic Composition of Brake Damper
Photos 3~4 V column and LR beam used in the
LRV method• LRV-H Method

In the LRV-H (left tight vertical horizontal
installation precast) method, two types ofmembers are adopted: precast column
members (H columns) that integrate columns and joints into a single structure andhave a full length that is similar to the floor
height, and precast beam members (Hbeams) that use the inner web depth as amember. In the column members, the penetration holes for primary reinforcement

WasherElongate holeOuter plate

Inner plate
Plate washer

Disc spring
Brake material
Stainless plate

Friction surface(Source : Obayashi Corporation)
April 2013 Steel Construction Today & Tomorrow 14

Latest High-rise Project

Loop Road No. 2 Project─Super High-rise Building on Urban Highway─
by Hiroshi Takahashi, Nihon Sekkei, Inc.

The “Loop Road No. 2 – Shimbashi / Toranomon Redevelopment Project, Zone III” is alarge-scale urban redevelopment project
proposed for the Toranomon area ofTokyo. A notable feature of this project isthat the planned Loop Road No. 2 willcross east to west through the development
site and under a yet-to-be-completed superhigh-rise building with a height of 247 m.
(Refer to Figs. 1 and 2)
The planned building is to be erected ona site of about 17,000 m 2 , will have 52
floors above ground and five below
ground, and will have a total floor area of
about 244,000 m 2 . As a mixed use building, the parking lot takes up the floors
below ground, shops and a conference
facility occupy floors 1 to 5 of the lower
level, and offices fill floors 6 to 35 of themedium-rise section. Beyond this, the 36th
floor is totally reserved for use as a spacetruss for a different arrangement of columns on the 37th floor and above. In thehigh-rise section, residential facilities arelocated from the 37th to the 46th floors,while a hotel occupies the 47th floor andabove.
Most of the redevelopment zone is occupied by the super high-rise building and theunderground section through which atunnel for Loop Road No. 2 passes. A
3-story commercial building is located at
the site, and a large freestanding eave that
protrudes from the 2nd floor of the highrise building overhangs the plaza beside thehigh-rise building.
Outline of Building Structure

The aboveground section of the super highrise building is mainly a rigid steel frame
structure (using concrete-filled steel tube
columns) with response-control devices
attached, and the commercial building andlarge eave are also steel frame structures.
The underground section is a mixed structure composed of steel framing, steel
frame-reinforced concrete, and reinforced
concrete. The podium structure (artificial
ground) on the Loop Road tunnel consists of
1 m-thick precast slabs.
As for construction of the foundation,
because the inverted construction method

15 Steel Construction Today & Tomorrow April 2013

Fig. 1 Perspective Drawing ofLoop Road No. 2 Project

Fig. 2 Arrangement of Various Structures
Large eave

Commercial building

was adopted in order to reduce the construction term, cast-in-place piles were used toform a piled raft foundation in which thepiles and spread foundation bear loads
respectively according to their rigidity.
Response-control Structure

A response-control structure was selected
for the aboveground portion of the highrise section, which has a plane shape of
85 m × 61 m, and response-control
devices are positioned in the various sections of the center core. In order tocreate a mega-frame that could effectively suppress bending deformation of
the entire building, the entire structure⎯from 1st story through the structureswitching truss up to the structureswitching section of the 51st story that
adopts a combination of inclined roofing

High-rise building

Loop Road No. 2

and shifted roof tops to form a distinctive
roof frame⎯is linked employing
response-control devices (Fig. 3).
A combination of three kinds of
response-control devices is used: oildampers (516), buckling-restraint braces(448) and friction dampers (620). A
response-control mechanism that capitalizes on this kind of combined use cansuccessfully secure high seismic resistance by reducing the inter-story drift
angle during an earthquake to 1.5-moretimes less than that of common high-risebuildings. (Refer to Fig. 4)
Connection for Tilted Column-crossed
Section

The tilted column system is adopted for thenorthwest, southeast and southwest cornersof the building for the following reasons:columns cannot be positioned above thearea covering Loop Road No. 2; and theFig. 3 Floor Framing of Standard Floors

Office floor

Residential floor
Location of response-control device

Fig. 4
Arrangement of
Response-control
Devices andStructure-switching
Truss

Fig. 5 Road Culvert Structure and Underground Building Structure
Slab on Loop Road No. 2(thickness: 1,000 mm,
precast reinforcedconcrete structure)

Road culvert structure

Friction damper
Oil damper
Buckling-restraint brace
Structure-switching truss
Loop Road No. 2

corners of the building must be finishedwith sharply acute angles for aesthetic purposes. From the 8th to the 13th floors, twotilted columns on each upper floor intersect
and combine to form a single column on thefloor below. Cast steel connections, eachweighing about 20 tons, are adopted forwhere the columns intersect so that thestress carried by the two upper columns canbe securely transferred to the single column
below. (Photo 1)

East-west section

South-north section

vibration not to affect the building, thebuilding structure is insulated from theculvert structure by sandwichingvibration-damping material (polyurethane
elastomer) between the culvert bottom slab
lower section and the building structure.
(Fig. 5)Large Eave

A large freestanding eave is installed on theplaza at the west side of the building. It has
skylights and measures about 57 m × 32 m
in outer dimension. Having an oval shape, it
stands at a height of about 22 m above thepodium structure. (Fig. 6)
The inner frame section, which is composed of skylight glass, adopts a singlelayer frame. In order to carry the inner
frame and to maintain its own high rigidity,
the frame is designed as a space truss composed mainly of steel pipes.

Fig. 6 Structural Frame for Large Eave

Photo 1 Cast steel connection for peripheral
tilted column-crossed section

Countermeasures against Road Vibration

Running underground, Loop Road No. 2connects on the east side of the building,at the second-basement level, with anunderground tunnel installed outside thedevelopment site, and then resurfaces on
the west side of the site. The road runs
through a tunnel-shaped culvert structurethat was built independently of the building structure. In order for road traffic

Vibration-damping material(polyurethane elastomer)

Photo 2 Construction of structure-switching truss

Photo 3 Entire view of Loop Road No. 2 Project
underway (November 2012)

Construction Is Steadily Proceeding

After demolition of the existing buildings, construction of the buildings
planned in the project began in April
2011. The aboveground steel framing isbeing installed simultaneously with construction of the underground structure,using the inverted method. Constructionof the structure-switching floor, a difficult section in the construction of theaboveground structure, has been successfully completed (Photo 2), and preparations are underway to build the complex
framing at the top of the building.
Construction of the road culvert has
started and is proceeding simultaneously with the high-rise building work.
After completion of the high-rise building structure, extensive construction
work will begin on the large eave, thecommercial building and the podium
structure. The grand opening for theentire project is scheduled in 2 0 1 4 .
■(Photo 3)
April 2013 Steel Construction Today & Tomorrow 16

Latest High-rise Project

Otemachi 1-6 Plan

─ Ultra High-rise Building Using World-class Ultra
High-strength CFT Columns─
by Shuichi Matsumoto and Shinichiro Kawamoto, Taisei Corporation
Building and Structural
Outlines

Fig. 1 Framing Elevation

This ultra high-rise buildinghas 38 stories above ground(including a three-story penthouse), stands 199.7 m talland has six basement floors
extending to a depth of 35.1
m. The total floor space isabout 198,000 m 2 . (Photo 1).
The main building functions
are: offices, a hotel and shops.
In terms of structural type,the underground floors arebuilt with reinforced concrete,
and the aboveground floors
form a steel structure that uses
CFT columns for the 1st
through 32nd floors. The
aboveground floors form amoment resisting frame structure with response-control
braces arranged at the core of
the building. The oil dampersthat are used as viscous dampers and the buckling-restraint
braces that employ low yieldpoint steel (LY225) for theaxial members and are used ashysteresis dampers are appropriately arranged so that seismic energy can be effectively
absorbed.
Mega-truss frames are adopted for the
4th and 32nd floors. These are structurechanging floors in which the structural
position of the columns changes in orderto realize a framing system that allows
different floor spans on the upper andlower floors. In order to secure adequate
habitability during strong winds, a
response-control device (active massdamper) is installed on the rooftop. (Refer
to Fig. 1)
Application of Ultra High-strength
CFT Columns

Photo 1 Building appearance
17 Steel Construction Today & Tomorrow April 2013

Response-control device(active mass damper)

Mega truss

Response-control device• Buckling-restraint brace• Oil damper

CFT column

Two requirements have increasingly
emerged in recent high-rise building construction projects: longer spans to enhance
freedom in the space design of standard
floors and wide atriums that promote structural continuity between the lower floors
and the surrounding external space. In
order to realize these two requisites, it isgenerally necessary for the structural members used in framing to bear large forces
and, as a result, to grow in volume. However, the appropriate combination of highstrength members can prevent excessive
increases in member volume.
As a structural technology to cope withsuch a task, we have developed worldclass, ultra high-strength, concrete-filledtubular (CFT) columns manufactured by
the combined use of high-strength concrete(design standard strength: 150 N/mm2) andhigh-strength steel products (tensile
strength: 780 N/mm 2 ). These ultra highstrength CFT columns are being used toconstruct the low-rise floors of the ultra
high-rise building in the Otemachi 1-6
Plan.

A unique feature of the Otemachi 1-6 Plan
is the creation of Otemachi Forest, a verdant 3,600-m 2 area of soil and greeneryprovided to the ground floor of the build-

Mega truss
Ultra high-strength
CFT column
Otemachi Forest

Subway concourse

Fig. 2 Combined Use of High-strength
Steel and High-strength Concretefor Ultra High-strength CFT Columns
Steel

Newly-developed ultra
high-strength CFT column

Range of application of
specifications and standards

ConcreteFig. 3 Application of Ultra High-strength CFT Column: Ultra high-strength CFT column

Ote

ma

chi

Fo

res

t

Fig. 4 Relation between Stress of Concrete and Steel and Strain
780 N/mm2

600

steel

500

300

400

490 N/mm2
300

200

Fc150

200

100
100

Fc100
Fc60

0
00

1000

2000

3000

4000

0
5000

Strain (μ)

such as welding tests supposing both factory and on-site welding of the ultra highstrength steel and both material and filling
confirmation tests on the ultra highstrength concrete. Then, after the structural
efficiency of these ultra high-strength CFT
columns was confirmed, the columns were
put into practical use.
Wide Floor Space Using Fewer
Columns

Photo 2 Ultra high-strength concrete-filledtubular (CFT) column

400

Stress applied to the concrete (N/mm2)

700

Stress applied to the steel (N/mm2)

ing site. In this regard, an important task inthe building plan was how to build safe
structural framing with no structural hindrances in the large space provided
between Otemachi Forest and the subway
concourse below.
The ultra high-strength CFT columns
applied in the low-rise section of the building were produced using 780 N/mm2 steel
and Fc150 N/mm2 concrete, which give thecolumns world-class strength (Fig. 2).
Adoption of these ultra high-strength CFT
columns in the low-rise section satisfies theabove-mentioned task in the building plan.
In addition, these columns meet therequirements for seismic safety (Fig. 3).
The elevated strength of these CFT columns suppresses the need to increase of thevolume of the column members, which inturn leads not only to a reduction in theuse of structural materials but also to themitigation of associated environmental burdens.
Fig. 4 shows the relation between strain
and the stress applied to the steel and concrete. The critical strain is nearly identicalfor both the 780 N/mm 2 steel and theFc150 N/mm2 concrete, which indicates thegreat advantage to be obtained by combining the use of high-strength concrete withhigh-strength steel. In addition to theextremely high vertical supporting capacitythat these ultra high-strength CFT columns
possess, they also exhibit a high yield ratio
and low elongation at the time of tensile
strength, thereby offering sufficient allowance to keep the building frame within its
elastic range.
In the development of these ultra highstrength CFT columns, structural performance was confirmed by means of structural testing, and, further, the structuraldesign work was conducted using thestrength assessment method. In addition,other extensive testing was conducted,

Still under construction, the building will
have a height of 199.7 m. Adoption ofultra high-strength CFT columns will
successfully produce large, wide spaces
with fewer columns on the lower floorsthat will structurally share the large burden

associated with ultra high-rise buildings.
■(Refer to Photo 2)

Reference

1) Shuichi Matsumoto, Tsutomu
Komuro, Hiroyuki Narihara, Shinichiro Kawamoto, Osamu Hosozawa
and Koji Morita: Structural Designof an Ultra High-rise Building
Using Concrete Filled Tubular
Column with Ultra High Strength
Materials, 15th World Conferenceon Earthquake Engineering(15WCEE), Lisbon, Portugal, 2012.

April 2013 Steel Construction Today & Tomorrow 18

JSSC Operations

JSSC Symposium 2012 on Structural Steel Construction

The Japanese Society of Steel Construction(JSSC) has annually held its JSSC Symposiumon Structural Steel Construction since 2004. The
major aim of this symposium is to comprehensively and functionally link operating results of
JSSC’s various committees and working groups
and to provide a venue for exchanges between
JSSC members and those working in steel
construction. The 2012 symposium was held on
November 15 and 16.
The 2012 symposium covered a wide rangeof events such as those shown in the attachedtable, and also the introduction of the 2012 JSSC
prize-winning works using panel exhibition. (Forthe prize-winning works, refer to pages 1~6.)
The total number of participants for the twoday 2012 symposium was about 1,000. Thisannual symposium serves as a useful venue forexchange between researchers and engineers
working in steel construction and for colleting thelatest information in steel construction.
The 2013 symposium is scheduled to be heldin Tokyo on November 14 and 15, 2013.

November 15, 2012

November 16, 2012

To Our Readers

and technological development aimed atpromoting the spread of steel construction andat improving associated technologies and,Toshiyuki Sugiyama
Chairman, International Committee, JSSC further, to extend cooperation to related organi(Professor, Graduate School ofzations overseas.
Yamanashi University)
Following the merger of JSSC with the StainI assumed the posi- less Steel Building Association of Japan intion of chairman of 2010, JSSC’s field of operation has expanded
the International to include not only carbon steel but also highly
Committee in 2012. corrosion-resistant stainless steel. ConseStarting with issue quently, we intend to actively transmit informaNo. 26 of Steel tion throughout the world that is related to a
Construction Today wider range of steel construction areas.
& Tomorrow, ourAs was true in issue No. 35, the previous
International Com- issue for which our committee was responsible,
mittee has been our current issue, No. 38, introduces the
responsible for the editorial planning of one of outstanding works that received JSSC Prizes
the three issues published annually. Since its and Thesis Prizes. A special feature of this issueinauguration, JSSC has conducted wide- treats advanced high-rise building technologies
ranging activities in the form of survey, research in Japan and the latest high-rise projects. Also

STEEL CONSTRUCTION TODAY & TOMORROW
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included is an outline of JSSC Symposium2012 on Structural Steel Construction.
The International Committee, while working
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Edited byCommittee on Overseas Market Promotion, The Japan Iron and Steel Federation
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