No. 31
November2010

A Joint Publication of The Japan Iron and Steel Federation and Japanese Society of Steel Construction
Tobu Railway Co., Ltd. and Tobu Tower Sky Tree Co., Ltd.

Special IssueTokyo Sky Tree®

Steel-frame Structures— Technological Trends and Developments —By Koji Morita
Professor of Tokyo Denki University, Emeritus Professor of Chiba University

Increasing Application of Seismicresistant Structures
Fig. 1 shows the percentage of steel-frame
high-rise buildings (60 m or higher) designed from FY2000 through the first half of
FY2006 that incorporated vibration-control
devices and base-isolation devices1). Fig. 2
shows the ratio of various dampers adopted1).
Primarily three types of hysteresis dampers have been adopted: steel plate seismicresistant walls that employ low-yield pointsteel having lower yield point limits (lower
limit for tensile strength) of 80 (200) N/mm2
and 205 (300) N/mm2; shear yielding panelsof Y-shaped braces and studs; and bucklingrestrained braces that employ low-yield
point steel and SN490B as the bracing material. The annual ratio of hysteresis dampers
adopted in building construction runs between 40% and 65% (refer to Fig. 2).
Among viscous-type dampers are viscoelastic materials, i.e. dampers that absorb
energy by means of shear deformation inviscous materials, and oil dampers that
adopt cylinder-and-piston energy absorption mechanisms. The ratio of viscous-type
dampers adopted each year ranges from lessthan 30% to more than 40%.
In addition, positive efforts are increasingly being directed toward the development of new dampers and their incorporation in design.
Various methods to improve the seismic
resistance of low- and medium-rise steelframe buildings have also been applied, depending on the application and importanceof the buildings. The design input seismic
motions for great earthquakes are set at
 Recent Steel-frame Technologies

Koji Morita: After graduating from the Department of Architecture, the University ofTokyo, he became an assistant of the University of Tokyo in 1969. Then he became
Associate Professor of Tokyo Denki University in 1971 and Professor of Chiba University in 1988. Currently, he is Professor of Tokyo Denki University and Emeritus Professorof Chiba University.

events. It will also be important to develop
connection details that will enhance the efficiency of damper-to-frame connections.

higher levels than those for general buildings. Further, in the case of adopting design
criteria to mitigate damage levels, it is considered effective to adopt a design methodthat suppresses frame damage by incorporating hysteresis dampers in the frame. In
order to promote seismic-resistant design
methods in the construction of low- and medium-rise buildings, it will be important todevelop dampers that are suitable for lowand medium-rise buildings and that are highin recoverability following disastrous

Diversified Yield Points and Tensile
Strengths of Steel Products
In addition to conventional steel with lower
yield point limits (lower limits for tensile
strength) of 235 (400), 325 (490), 355 (520)
and 440 (590) N/mm2, ministerial approvalhas been given for steel offering various other levels of lower yield point limits (tensile

Fig. 1	Ratio of Buildings Incorporating Vibration-control and Base-isolation
Devices in Steel-frame High-rise Buildings
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

No use of dampers
1 kind of damper

2 or more kinds ofdamperBase-isolation device+ 1 kind of damper
Base-isolation device
2000

2001

2002

2003

2004 2005.2006

Fig. 2 Ratio of Various Dampers Adopted
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

Viscous damper
Other dampers
Buckling-restrained brace
Low yield point steel
panel (stud, y-shaped brace)
2000

2001

2002

2003

2004 2005.2006

Low yield point steel
seismic-resistant wall

Building Construction
strengths). These are:● Steel grades for plates and circular tubes:
385 (550), 400 (490) (fHAZ≤0.58 for plate),
440 (590) (conventional SA440 steel forplate), 500 (590), 630 (780) and 700 (780)(only H-SA700 plate)-N/mm2 and● Steel grades for square tubes: 385 (550),400 (490) (fHAZ≤0.58) and 440 (590)-N/
mm2.
While some of these steel grades requireapplication approval in terms of structuraldesign methods, the available range of yield
points now extends from 235 N/mm2 to 700
N/mm2. In addition, for steel plates withyield points from 325 N/mm2 to 440 N/mm2,
steel for large heat-input welding has beendeveloped.
Of these steel products, plates with lower
yield point limits of 325 N/mm2 or more andthicknesses of 40 mm or more are producedby means of the water cooling-type thermomechanical control process (TMCP) or by
the QQ’T process that involves initialquenching followed by subsequent dualphase quenching and tempering. However,for steel products having a lower tensile
strength limit of 780 N/mm2, it is expectedthat steel with high weldability will be developed along with welding materials capable of securing toughness in the weld metal
while not lowering that of the base metal.
Further, it is considered necessary to organize statistical data on the mechanical properties of steel products produced using thesediversified grades and their welds as design
data.
Fig. 3 shows the ratio of maximum
strengths (lower limits for tensile strength)
possessed by steel products adopted for thecolumns of steel-frame high-rise buildings1).
When these products are classified by production process, the 325 (490) N/mm2 grade
produced by hot rolling accounts for nearly
30%, and the 325 (490), 355 (520) and 385(550) N/mm2-grades by TMCP and the 440(590) N/mm2-grade by QQ’T together ac-

count for nearly 70%. Recently, 630 (780)
N/mm2-grade QQ’T steel products that take
into account cyclic behavior in the plastic
range have been adopted for the steel plate
seismic-resistant walls of large-span highrise building structures and for heavy-wall,large-section concrete-filled steel tube columns whose elastic limits are specified in
the design conditions.
For the Tokyo Sky Tree®, a steel radiobroadcasting tower now under constructionin Tokyo that will be introduced later, diverse kinds of heavy-wall, large-section circular steel pipes in addition to 630 (780) N/
mm2-grade steel products have been adopted as the appropriate materials and in theright sections.
It is considered that structural design
freedom has been remarkably enhanced byappropriately selecting the steel products
mentioned above according to the performances required of the structural members.
Steel-frame structures are the most suitable
type of building for creating free space, andtheir adoption is expected to bring forth demand for new structural space.
Collaboration between Structural
Designers and Steel-frame Fabricating Companies
Numerous types of steel-frame fabricatingcompanies are in operation. Certain companies are able to manufacture highly precise
structures in which structural members using heavy-wall, large-section high-strength
steel products are connected in complex
three-dimensional arrays. Other companies
engage mainly in the manufacture of rigid
steel frames using square tube columns andH beams. All of these companies have accumulated knowhow regarding their respective fabricating technologies and havesteadily enhanced their ability to guarantee
steel-frame quality. It is regarded that this islargely attributable to the steady technological developments, diffusion activities, andFig. 3 Maximum Strength of Steel Products Used for Columns
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

590 N/mm2 grade
550 N/mm2 grade

520 N/mm2 grade
490 N/mm2 grade
2000

2001

2002

2003

2004 2005.2006

engineer-development activities of the Japan Steel-rib Fabricating Association and
the Japan Steel Constructors Association, in
addition to the extensive efforts of the respective steel-frame fabricating companies.
Structural designers have enhanced theircollaboration with steel-frame fabricatingcompanies through periodic exchanges oftechnological information and by implementing structural design that features easeof fabrication performance that, in turn, reflects technical proposals from the steelframe fabricating companies. Further developments in design and fabrication
technologies for steel-frame buildings are
expected to spring forth from these collaborative efforts.
Further, at steel-frame fabrication companies, diverse operations are being directed
toward labor and energy savings, including
contributions to the creation of a low-carbon
society. Specifically, in welding operations,
efforts are being made to reduce welding
volume and weld corrections by reviewing
current groove standards. Activities are also
being promoted that reinforce energy-saving fabrication operations, including process controls to allow optimal fabricationand to lessen member movement. In this regard, close cooperation between designers
and fabricating companies will be required,
meaning that structural designers and construction companies will need to agree earlyin the process on design changes, changes inconstruction methods, finishing degree, therequired equipment, and temporary construction metal fitting-related connection
details so that the steel-frame fabrication
process can be free of disturbance.
A good example of collaboration between structural designers and steel-frame
fabricating engineers is the design of thesteel-frame details and the fabrication of thesteel frames adopted for construction of theTokyo Sky Tree®. It is regarded that the construction of this, the world’s tallest steel
tower, has been possible only through collaborative operations based on the advanced
design technologies of the structural designers and the advanced steel-frame fabrication
technologies and quality guarantee capabilities of the steel-frame fabricating companies.
Reference1)	New Building Technology Report―Performance Assessment and Rating/Examination
Certification (June 2000, March 2009):
Building Center of Japan, June 2010
Recent Steel-frame Technologies Tokyo Sky Tree
— Creation of a Landscape beyond Space-time —By Shigeru Yoshino
Design Partner, Nikken Sekkei Ltd.

Area in and around Construction
Site for Tokyo Sky Tree
bu
za

Ise
ine

ki L
is

aR

ei

Ar

Li
n

e

SumidaR.

HigashiMukojima Sta.

.

Ke

Hikifune Sta.
Tobu Asakusa Sta.
Narihirabashi Sta.

Asakusa Sta.

Tokyo Sky TreeTo

bu

Oshiage Sta.
Kit
ajik
ke
nR

Ryogoku Sta.
Kinshicho Sta.
JR Sobu Line

Toei Subway Oedo Line

Tokyo Metro
Hanzomon Line

Ka

Nak

aga

me

ido

Lin

e

.

Yokojikken R.

 Landscape beyond Space-time

On the other hand, as regards the tower’s
two observatories, because it was supposedthat visitors might want to look in the direction of their homes, importance was placedon providing a 360-degree view of the entire
Kanto area. To that end, it was found that acircular form would be appropriate for theobservatories. In addition, the adoption of acircular form would make it more convenient for attaching antennas in any direction.
Also, a circular design, when subjected toexternal forces, is better than a triangularform in meeting external forces exerted
from any direction in a well-balanced manner in order to maintain tower stability.
As a result, the tower configuration progressively changes from a triangular shapeTo

High-rise Tower in the Shitamachi
District
Rising high above the Narihirabashi-O­shi­
age area of Sumida Ward, the Tokyo Sky
Tree is surrounded by several shitamachi areas (traditional shopping and entertainment
districts), such as Asakusa and Mukojima. It
is also located at a strategic point where the
Tobu railway line, subway lines, and waterborne transport services converge. The Tokyo Sky Tree not only serves as a self-supporting radio broadcasting tower thattransmits terrestrial digital and other broadcast signals. It also symbolizes the revitalization of shitamachi areas and shitamachi
culture, while at the same time enhancing
ties with Asakusa, a famous sightseeing
place in Tokyo that is rich in traces of Edo
culture. To meet these needs, studies wereconducted on the design of the tower to ensure a deep connection with the unique geographical features of these areas.
The construction site lies at the center ofa topographical triangle bordered on twosides by the Sumida and Ara Rivers that foster the ever-lasting flows beyond the ages
and on the south by railways and major
highways that run from east to west. The
tower is located at a critical point where diverse “avenues” converge that have orthotropic crossing with these three urban axes.

Flat triangular framing was examined forthe tower base so that it could welcome visitors entering from these avenues.
As a downward sweeping structure, thetower is reminiscent of an ancient Chinese
kanae or tripod kettle (self-supporting withthree legs) that imparts a sense of stability tothose who view it. In addition, the triangularshape allowed the maximum possible width
for the tower’s base within the confines of
the construction site and, further, its adoption allowed for the introduction of a stablestructure requiring the minimum use ofstructural members. Also, careful consideration given to the tower design helped to
avoid any sense of oppressiveness in surrounding areas.

T
As oei
ak Su
us bw
a a
Li y
ne

Facing the Sumida River in the eastern partof Tokyo, the Narihirabashi and Oshiage areas were once flourishing centers of Edo
culture (17th to late 19th century). In February 2006 the Tobu Railway Co. proposed to
local broadcasting companies and to Sumida Ward that a huge steel tower, called theTokyo Sky Tree®, be built there. The firstthing particularly emphasized by the clientat the start of the project was the “creationof a landscape beyond space-time there.”
During subsequent stages of the design
work, consistent efforts were made to realize this theme.

wa
R

.

Building Construction
Aerial View of Tokyo Sky Tree upon Completionat the base to a circular form higher up―
giving the tower a unique configuration notfound anywhere else in the world.
Changing Configuration of theTower
The changing configuration of the tower
from a triangular to a circular shape pro­duces “warping” and “camper” in the tower
design, forms that are found in traditional
Japanese culture. The triangular cross-section that dominates the lower section of thetower becomes circular at a height of about
300 m above ground.
When viewed from the side, each of thelines extending upward from the groundalong the triangular part of the tower draws
a gently depressed arc. Etched clearly
against the sky, this arc closely resembles
the “warping” seen in katana, or Japaneseswords. The diagonal lines that girdle thethree sides of the triangle form a gentle convex pattern called “camper.” An example ofthis is the subtle swelling seen in the colonnades of Japanese shrines and temples. At
first view, the configuration of the towerseems simple, but in actuality it contains extremely complex curves.
Tower Design Transcends Spacetime
The world’s most prominent towers arecommonly located on a clear urban axis, asis the Eiffel in Paris, or next to the sea, alake, or a river, such as the CN Tower in Toronto and the Oriental Pearl Tower (TV tower) in Shanghai.

Elevation View ofTokyo Sky Tree

Tobu Railway Co., Ltd. and Tobu Tower Sky Tree Co., Ltd.

There are two perspectives from which asingle tower can be viewed: one is from a
distance with the tower soaring upwardfrom the ground, and the other is from thebase of the tower looking up at the sky.
These two perspectives stand out in thememories of tower visitors.
On the other hand, for the Tokyo Sky
Tree, it is the distant view from beyond theSumida River that is most memorable. From
the avenues running in diverse patterns inneighboring shitamachi to just beneath thetower, the gently changing appearance ofthe tower from a triangular shape to a circular shape emphasizes the tower’s unique interplay of warping and camper. Offering diverse appearances depending on the pointfrom which it is viewed, the tower is linked
to the quintessential nature of the shitamachi alleyways and to the freedom, change
and originality peculiar to the Edo merchantclass. Accordingly, the tower is not an independent production; rather, its appearance isbrought about by the consolidated embodiment of the tower itself and shitamachi characteristics.
A new architectural landscape will beborn. In it, the Tokyo Sky Tree will employ
advanced technologies and never-beforeadopted design approaches. At the sametime, it will inherit and embody the deeply
rooted culture of the locality in which it
stands. We believe that the landscape thus
created will manifest the theme: “creation ofa landscape beyond space-time.”

Landscape beyond Space-time Tokyo Sky Tree
— Structural Outline of Terrestrial Digital Broadcasting
Tower —
By Michio Keii, Atsuo Konishi, Yasuo Kagami, Kazunari Watanabe, Norio Nakanishi and Yoshisato Esaka
Structural Design Department, Nikken Sekkei Ltd.
Construction of the Tokyo Sky Tree®, adigital terrestrial broadcasting tower with aheight of 634 m, was started in July 2008
in Sumida City, Tokyo. The tower will not
only transmit digital terrestrial broadcasting that is slated to begin in the spring of2012 in Japan; it will also serve as a symbolof efforts to achieve community affluence.
Outline of Tokyo Sky Tree Plan●P
 lanned Site and Facility Arrangement Plan
The area in and around Oshiage and Narihirabashi Stations, the site planned for theconstruction of the Tokyo Sky Tree, is located near the center of Sumida City, Tokyo. Specifically, the site is located where
two urban axes of Sumida City cross: thecentral east-west axis that passes throughthe site via the Azumabashi area from Ueno
and Asakusa and the south-north axis that
leads to the area in and around Hikifune
Station from the area in and around Kinshicho Station.
The facility layout is divided into three
sections: the west district mainly for commercial facilities (utilized by local entities), the tower district, and the east district
mainly for shops (sightseeing) and offices

BalloonPhotos 1 and 2  Observation of high-level winds by mans of radiosonde(refer to Fig. 1). The tower is located in thecenter of the planned site and will constitute the nucleus of a complex that is rich inenjoyable excursions and bustling activity.
Design Loads and Criteria● Wind Loads— Settlement of Height-direction
Characteristics of Natural Winds
Because Tokyo Bay is located about 8 km
south of the tower and because the tower is
634 m high, it was taken into account thatthe ground surface boundary layer that reflects the surface roughness of the peripheral districts cannot fully develop, which
led to the adoption of the “roughness clas-

Fig. 1 Entire Arrangement Plan
West district

tationshi Shiraba

Nari

(Tobu

Tower district

East districtline)

Oshiage Station(Tobu and Keiseilines, Tokyo Metroand Toei subway
lines)

Kitajikken River Structural Outline of Tokyo Sky Treesification II” prescribed in the Building
Load Guidelines and Commentary (2004)
of Architectural Institute of Japan (AIJ).
The boundary layer height was prescribed to exit above the planned tower,
and the average wind velocity was calculated with the provision that the profile ofaverage wind velocity can be extrapolated
in the height of ZG or more in the power law
distribution, which is adopted in the AIJ
Guidelines.
It was also prescribed that the AIJ
Guidelines be extrapolated in the height of
ZG or more pertaining to the wind scale andthe height-direction distribution of wind
turbulence, as was done for the profile ofaverage wind velocity. However, the wind
turbulence was settled at a minimum of
10% to provide the lower limit. (Refer to
Photos 1 and 2)— Settlement of Assumed Storms
in Design and Design Wind
Loads
Table 1 shows the storms that are assumed
within the design. The wind forces working on the planned tower by each level ofstorm was found providing that: for level 2storms, the equivalent static wind load wasfound according to the procedure shown in
Fig. 2; and for level 1 and 3 storms, thewind force is in proportion to the square of
the basic wind velocity.

Building Construction
Fig. 3 Comparison of Spectrums

Name of storm

Return period

Average wind velocity equivalent to basic wind velocity

Level 1 storm  100 years

36.0 m/s

Level 2 storm  500 years

40.0 m/s

Level 3 storm

2,000 years

44.7 m/s

response analysis forthe adopted seismic
motions shown in Table(1) Settlement of height-direction characteristics of natural wind
• Taking into account that the ground surface boundary layer that reflects the surface rough2 to prove the safety ofness of the peripheral districts cannot fully develop, the roughness classification II is adopted.
• It is provided that the profile of average wind velocity can be extrapolated in the height of Z
all structural members.
or more in the power law distribution.
— Adopted Seismic
Motions(2) Wind tunnel test (physical simulation)• A wind tunnel test is conducted in which the natural wind height-direction characteristics settled
The seismic motions
as the target values are simulated in the boundary layer wind tunnel, and the basic data to
adopted for the tower
prepare the simulated wind force wave is measured.
design were selected by(3) Time-history response analysis by means of simulated wind force wave (logical simulation)
preparing a so-called• Targeting the power spectrum density of fluctuating overturning moment found in the windsite wave that supposes
tunnel test, a simulated wind force wave is prepared by means of the Monte Carlo simulation.
the case in which along-period earthquake(4) Settlement of equivalent static wind load and analysis of static stress• Time-history response analysis is conducted by giving to the multi-mass point model theand an in-land direct
simulated wind force wave prepared based on the wind tunnel test, and the wind response of
the tower is found.
hit-type earthquake oc• Equivalent static wind load is set at the average load of response story shear force.
cur near the tower; alsoutilized were simulated(5) Proving structural safety to wind load (confirmation of deformation, examination of sections)• Structural safety to the wind load is proven by confirming that each structural member satisfies
waves (required in thethe target criteria pertaining to the equivalent static wind load.
Building Standard Law
of Japan) and observed
waves adopted in the design of common● Seismic Loads
high-rise buildings. Fig. 3 shows the re— Directions to Examine Structuralsponse spectrum of part of the adopted
Safety during Earthquakes
Because the tower is 634 m high, the high- seismic motions.
er mode and the axial deformation of thestructural members have a large affect, and ● Design Criteria
it is difficult to appropriately define the de- The tower was designed so that the stresssign seismic load by means of the “enve- of the structural members, excluding weld
lope load of response layer shearing force” connections, remains within an elastic
that is conventionally adopted in the design range against level 2 earthquakes and theof common high-rise buildings. To meet wind loads shown in Table 3. Meanwhile,
such a situation, the structural safety of the in addition to the above-mentioned design
tower during earthquakes was examined by criteria pertaining to structural safety, it isconducting a member-level time-history required that the structural performance be
Fig. 2	Wind Resistance Design Flow (Preparation ofEquivalent Static Wind Loads)

Simulated wave: NS earthquake, Kobe Marine Observatory
Site wave: Minami-Kanto earthquake
Site wave: Direct hit-type earthquake

Shaking resistance of building

Table 1	Return Period of Storm Level and Average Wind Velocity equivalent
to Basic Wind Velocity

G

Table 2 Adopted Seismic Waves
Input level

Adopted seismic wave

Level 1 earthquake
Simulated wave
(Rarely occurring seismic motion) Observed wave
Simulated wave
Level 2 earthquake(Extremely rarely occurring seis- Observed wave
mic motion)
Minami-Kanto earthquake (M7.9: Site wave)
Tokai earthquake(M8.0: Substantial site wave)
Tokai earthquake(M8.0: LOVE site wave)
Higashi-Nankai earthquake (M8.2: LOVE site wave)
Nankai earthquake(M8.6: LOVE site wave)
Level 3 earthquake

In-land direct hit-type earthquake having an epicenter justbeneath the surface area (M6.9: Site wave)

Site wave: Surface wave,
Primary natural period of the tower
Tokai earthquake
Primary natural period of the building

suitable for use as a radio broadcasting
tower, the description of which however isomitted in the current article.
Design of Upper Structures● Framing Plan
A reinforced-concrete (RC) cylindricalshaped stairwell (shimbashira) is located at
the center of the tower, and steel-frame
cores (intermediate tower and inner tower)
into which elevators, EPS and other equipment are incorporated are located aroundthe stairwell. Their outer section is structured as a truss structure employing steel
pipes, and the plane configuration of thetruss structure at the tower base changes toa circular form. (Refer to Fig. 4)
The trusses, called kanae (tripod kettle)
trusses, are composed of four main members and are located in each corner of theequilateral triangle of the tower base, andthese trusses are connected in the horizontal structural plane as shown in Fig. 5. The
kanae trusses and the peripheral framing(outer tower) provide the main resistanceto seismic forces and wind loads.
● Steel Products Applied
Table 4 shows the steel products applied as
the main structural members in the tower
construction. In the current design, because
not only the tower is high but also its widthto-height ratio is quite large in relation to
the site, the sectional force working oneach structural member during earthquakes
and typhoons becomes large. To meet suchneeds, structural members having both
high strength and a large cross section are
required. Due to the same reasons, thepremise for the member joining method is
Structural Outline of Tokyo Sky Tree Fig. 5 Floor Plan
Table 3 Seismic- and Wind-resistant Design Criteria
Input level

Damage level

Level 1 earthquake (rarely occurring seismic motion)
Level 1 storm (return period of 100 years)

No damage

Level 2 earthquake (extremely rarely occurring seismic motion) Nearly no damage
Level 2 storm (return period of 500 years)(members in elastic range)
Level 3 earthquake
Level 3 storm (return period of 2,000 years)

No collapse

EV space

Maintenance deck

Fig. 4 Framing Drawing
Horizontally-connected
trussIntermediate tower

Kanae truss

Rib truss
Ring truss
Plan: Ring story
Kanae truss
Outer tower
Intermediate
tower
Inner tower
ShimbashiraRib truss
Horizontally-connected truss
Ring truss
Plan: Horizontally-connected truss

Rib truss
Kanae truss

Ring truss

Kanae truss● Built-up column employing four columns, and horizontal and brace
members● Arranged in the top of the triangular plane form
● Main member to resist horizontal load
Horizontally-connected trusses● Connecting intermediate tower and ring trusses every two layers(25 m)● Working as members to transfer the horizontal load (in-plane), andmembers to stiffen the buckling of kanae trusses and peripheral
columns
Ring truss● Horizontal members arranged every layer (12.5 m)● Working as the member to stiffen buckling of peripheral columns

the adoption of welding. Further, due to theheavy weight of each member, it was determined that the members would be divided
into shorter sizes conforming to the transport and lifting conditions, and that thesemembers would then be transported to theconstruction site and joined together bymeans of on-site welding.
Given such circumstances, it was necessary to adopt steel products that were not
only high in strength and toughness but
also excellent in weldability including preheating performance. The steel products
having a yield strength of 400 N/mm2 or
more that are used in the construction of
the Tokyo Sky Tree satisfy the performances thus required, and, at the same time,
have been approved by the Minister ofLand, Infrastructure, Transport and Tourism particularly for use in the constructionof this tower.
● Design of Tubular Joints
Because kanae trusses and structural members such as columns, braces and horizontal members for the outer tower are threedimensionally linked together to form
connections, steel pipe was adopted interms of the cross section, and the so-calledtubular joint method (Fig. 6) was adopted
to join the pipe members. The reason why
the tubular joint method was adopted in-Table 4 Steel Product Application Sections and Wall Thicknesses
Structural section

Zone

Outside diameter x Wall thickness (mm) Yield point

ColumnKanae truss

P-711.2 ø × 28 ~ 2300 ø × 100

400 ~ 500 N/mm2 grade

Outer tower

P-1100 ø × 25 ~ 1016 ø × 60

SN490B, 400 ~ 500 N/mm2 grade

Antenna tower

P-900 ø × 25 ~ 1200 ø × 80

SN490B, 400 ~ 500 N/mm2 grade,
630 N/mm2 grade

Outer tower

P-508 ø × 16 ~ 1000 ø × 60

SN490B, 400 N/mm2 grade

Antenna tower

P-300 ø × 22 ~ 500 ø × 22

SN490B, 400 ~ 500 N/mm2 gradeBrace

P-267.4 ø × 12 ~ 609.6 ø × 16
Horizontal member Outer tower, kanae trussof tower structure Horizontally-connected truss, BX-300 × 300 × 9 × 9ring truss Structural Outline of Tokyo Sky Tree     ~ 500 × 500 × 12 × 12

Circular pipe

SN490B (Partly SCN590B-CF)STKR490, BCP325

Square pipeBuilding Construction
cludes, for example, Fig. 6	Tubular
Joint
a neat finished apMethod
pearance and fewer
shortcomings withregard to corrosion
protection.
However,
because there are cases in which confirmation of the safetyof tubular joints employing large crosssection
highstrength steel pipe
used in the current
project is beyond
the scope of theSteel Pipe Truss Design Guidelines of
the Architectural Institute of Japan, thestrength of the tubular joints including connections was confirmed based on API(American Petroleum In­stitute) Specifications complimented by the use of the AIJ
Guidelines and FEM analysis.
The strength of these joints was examined as in the following: The strength tosupport wind loads was examined by meansof the design wind load (static load); and,because the static design seismic load is notdefined, the strength to support the seismic
load was examined by means of a step-bystep approach based on time-history analysis. Further, examinations were made of fatigue in all connections that would be
attributable to wind and earthquakes in order to confirm the safety of the connections. Fig. 7 shows the flow chart of the fatigue examination.
Design of Foundation Structures● Outline of the Ground at the Site
The planned site is located in a low-lying
area of Tokyo surrounded by the Sumida
and Ara Rivers. While the surface layer topography at the site is classified as sandbar-back marsh, the surface layer area inand around the planned site is composed
extensively of artificial reclamation topography.
The geology in the vicinity of theplanned site is composed of such diluvial
deposits as the Tokyo gravel layer, Tokyo
layer, buried terrace gravel layer and buried loam layer, along with such diluvial
layers as the Yurakucho layer in the vicinity of the ground surface, with the Kazusa
layer group including the Edogawa layer
and Toneri Layer as the foundation bed.

Fig. 7 Examination Flow of Fatigue of Tubular Joint
Time-history response analysis of wind: Level 1 wind, level 2 wind

Extraction of time-history stress response wave form of all members

Calculation of nominal stress amplitude αi and frequency ni by means of therain-flow method

Equivalent stress to disturbance at each level

S-N curve (AWS: ET, K2) that takes into account the stress concentration
factor (S, C, F)

Confirmation of cumulative
damage rate:

NG

Increase of wall thickness of
main pipe connection section

OK
Increase of wall thickness of main pipe connection section*For the reference sake, examination is made of the case of adopting the hot-spot stress method.

The thickness of the Yurakucho layer isabout 25~30 m, and its upper section iscomposed mainly of a loose sandy layerthat is 5 m in thickness and its lower section is mainly clay soil.
The ground surveys currently conducted are shown in the following:● Boring survey● On-site permeability test
● Borehole horizontal loading test
● Laboratory soil test
● PS logging● Constant slow motion measurement● Slow motion array search
Fig. 8 shows the soil boring log obtained
from the boring surveys.
— Predominant Period of Ground
The predominant period of the ground wasmeasured for the long period of 1 second or
more: 7.0~9.0 and 3.0~4.0 seconds; and ofless than 1 second: 0.4~0.5 and 0.6~0.7
seconds.
— Slow Motion Array Search Results
The depth (vs ≥ 3,000 m/sec) of seismic
bedrock was assumed to be about 2.5 km.
● Design of Foundation Structures
The foundation structure of the tower wasconstructed on a bearing stratum composedof a rigid diluvial gravel layer located in
GL–35 m or deeper. It is composed of continuous subterranean reinforced-concrete(RC) pile walls with high strength and rigidity and cast-in-place RC piles. In particular, for the base section of the tower
structure, common continuous subterranean RC pile walls were arranged, and justbeneath the kanae trusses, SRC (steel-reinforced concrete) pile walls were arranged(see Fig. 9). In order to provide large withdrawing resistance to SRC piles, a knot
was attached to these piles, and these knotattached SRC piles were driven to depths
as great as GL–50 m. Further, H-shapes
were arranged within the pile walls to provide higher tensile strength to the wall
structure. The withdrawing resistance of
the knot-attached piles was confirmed byconducting a full-scale test at the site.
● SRC Foundation Structure to
Securely Transfer the Withdrawing Resistance to the Pile
Large bending and shearing forces fromthe above steel-frame tower work on thefoundation structure (Fig. 10), and accordingly the SRC wall into which the steel
plate wall is built in conformity with theplane shape of the foundation was arranged
Structural Outline of Tokyo Sky Tree Fig. 8 Soil Boring Log at Construction Site

Fig. 10 Foundation Structure

Yurakucho layer (clay layer)
N0.1
H=0.38m
dep=65.30m

Altitude TP(m)N0.3
H=0.69m
dep=130.00m

N0.5
H=0.95m
dep=65.40m

N value

N value

N value

Tower section
1st floor
Altitude TP(m)Steel plate
Alluvial layer
Bearing stratum(Buried terrace
gravel layer)
Depth: GL-35 m

Foundation
sectionSteel plate

Steel plateDiluvial layer−

Alluvial layer

Geological classification−

Yurakucho
layer upper
sectionYurakucho
layer lower
sectionsymbolSurface soil, buried layer

B

Clay soil layer

Yuc

Sandy soil layer

Yus

Primary clay soil layer

Ylc1

Steel-frame
memberSecondary clay soil layer Ylc2

Buried roam layer Clay soil layer
Sandy soil layerblbts

Buried terrace
Sandy and gravel layer btg
layer
Sandy/clay soil layer btsc
Tokyo layer
group

Sandy soil layer (gravel) layer Tos
Sandy and gravel layer Tog

Kazusa layer group Sandy soil layer

Kas

Fig. 9 Piles Adopted

Fig. 11 Conceptual Drawing of Shimbashira Vibration Control

Oildamper

SRC knot-attachedcontinuous subterranean
wall pileGL– about 50 m
RC continuous
subterranean wall pileGL– about 35 m

Operatingrange

8000 mmDiluvial layer

Quaternary

Geologicalage

SRC
continuous
subterranean
wall pile

Pile section

EXP.J EXP.J
UP

UP

ShimbashiraRange higher than 100 m
Shimbashira wall thickness: 600 mm

Cast-in-place pileGL– about 35 m

in the foundation structure. The thicknessof the steel plate wall was set at 55 mm and
22 mm, and that of the RC wall at 2,700mm and 1,900 mm.

 Structural Outline of Tokyo Sky TreeOil damper

SectionShimbashiraSteelproduct
8000 mm

Outline of Vibration Control by
ShimbashiraFor the tower, the vibration-control system
shown in Fig. 11 was adopted to reduce response particularly during earthquakes.
Specifically, the RC shimbashira and its
outside steel-frame section are separated
from each other at a height of 125 m or
more, and the vibration-control system bymeans of mass additive mechanism thatutilizes the shimbashira weight (mass) in
the separated section has been devised andadopted. Integration of shimbashira and its
outside steel-frame section by use of steel
products at heights of 125 m or less and installation of oil dampers at heights of 125
m or more not only allow the control of displacement of shimbashira but add damping
performance to the entire tower structure.
The response shearing force can be reduced
by about 40% at maximum during greatearthquakes through adoption of the shimbashira vibration-control system.

EXP.J EXP.J
UP

UP

Fixed range
Range lower than 100 m
Shimbashira wall thickness: 400 mm

EXP.J

EXP.J

Section of column base
T. P. -33.9 m

ShimbashiraBuilding Construction

Tokyo Sky Tree
— Construction of World-class Steel Tower —By Obayashi Corporation
The tallest self-supporting tower in theworld is being constructed in Tokyo.
Named the Tokyo Sky Tree®, this 634 mhigh tower serves as a freestanding radio
broadcasting tower that transmits terrestrial digital and other broadcast signals.

Among the major facilities of the tower arean antenna tower, a first observatory (350m high) and a second observatory (450 mhigh).
The lowest section of the tower is triangular in plan and supported by three legs.

Project Outline• Name: Tokyo Sky Tree®
• Location: 1-chome Oshiage, Sumida-ku, Tokyo• Site area: Approximately 36,900 m2 (tower plus
the East and West districts)• Height: 634 m• Building type: Observatory (first at 350 m, second at 450 m)• Structure: Steel, steel-reinforced concrete, andThe shape becomes gradually more rounded, until at the height of about 300 m it becomes a perfect circle. The major advanced
construction technologies and materials
adopted in the construction of the Tokyo
Sky Tree are introduced below.

reinforced concrete• Foundation work: Cast-in-place concrete piles
and underground continuous wall piles• Commencement of work: July 2008
• Planned completion: December 2011
• Client: Tobu Tower Sky Tree Co., Ltd.
• Architect: Nikken Sekkei Ltd.
• Constructor: Obayashi Corporation

Second observatory
(450 m)First observatory (350 m)Obayashi Corporation

Elevation

Spring 2009

Obayashi Corporation
Construction of World-class Tower 10

Assembly of Antenna Tower by theLift-up Method
The tower’s uppermost section, the TV antenna tower, will be assembled on the
ground and then hauled up with cables

through the inside of the tower to the final
height of 634 m, using a dynamic “lift-up
method.” The on-the-ground assembly of
the antenna tower begins with its top section inside the still-hollow space in the cen-ter of the tower prior to the construction of
shimbashira (center column). The antenna
tower is gradually hauled up, and successive segments are added below. The completed antenna tower, measuring more thanFig. 2 Lift-up Method

Fig. 1 Structural Outline of Tokyo Sky Tree

Vibration control cap

Antenna
Antenna tower

Antenna tower

Cross section at the height of 585 m

500 m

Cross section at 400 m
400 m
Obayashi Corporation

Cross section at 300 m
300 m
Shimbashira(with stairwell)

200 m
Cross section at 200 m

Tower structure(steel pipe truss)
Shaft

100 m

Cross section at 50 m

0m

Cross section at 0 m
Foundation pile
Obayashi Corporation

11 Construction of World-class Tower

Autumn 2009

Obayashi Corporation

Building Construction
are only about 4 m long.
Steel Truss Structures
The tower itself is a truss of vertical, horizontal, and diagonal girders. Nearly all of
the girders are high-strength steel pipes,
which are directly welded together using
the “multi-coupling” technique, allowing
for clean and smooth joints. (Refer to Fig.
5)
Fig. 5 Multi-coupling Joint

Fig. 4 Giant Steel Pipe

10

cm
m

Construction of Shimbashira by
Slipform Method
In the space left empty after the lift-up of
the antenna tower, the shimbashira (center
column) will be built using the “slipform
method” by which concrete is continuously
poured into a form that slips upward as thepreviously poured concrete hardens behindit (Fig. 3).
With this technology patented by
Obayashi Corporation, the cylindrical concrete core can be constructed in a short period of time within the limited space at thecenter of the tower. The hollow space within the structure can therefore be used for
assembling and lifting up the antenna tower before the shimbashira is put in place by
the slipform method.

Assembly of Giant Steel Pipes
The tower is composed of wide-bore highstrength steel pipes rarely found in building
construction. Due to their sheer weight andsize and because of transport regulations,the pipes are made in sections weighing under 30 tons at fabrication plants all around
Japan. The sections are then transported tothe site and assembled using a tower cranewith lifting capacity of 32 tons.
The largest sections used at the foot of
the tower are 2.3 m in diameter, made from
10 cm-thick steel plates (Fig. 4). Becauseof weight restraints, these largest sections

2.3

200 m and with a stairwell in its lower section, is then moved up through and out of
the tower to its final position on top. (Refer
to Figs. 1 and 2)
With the lift-up method, assembling
work at an unprecedented height of over
500 m can be omitted, assuring safety andquality. The construction period is greatly
shortened as the antenna tower is assembled on the ground in parallel with the construction of the tower above the first observatory.

Obayashi Corporation

Obayashi Corporation

Fig. 3 Slipform Method

Shimbashira(center column)

Obayashi Corporation

Summer 2010

Obayashi Corporation
Construction of World-class Tower 12

Knuckle Walls“Knuckle walls” developed by Obayashi
Corporation are used as the foundation
piles supporting the world’s tallest tower.
For the tower to be able to withstand theuplift and compressive forces of earthquakes and strong winds, these piles havenodule-like protrusions that work to holdthe piles firmly in the ground, greatly increasing their strength in supporting thetower (Fig. 6). The wall shape of the piles
also enhances their rigidity and resistanceto the horizontal forces generated by earthquakes.

Fig. 6 Knuckle Wall

Compressive
force

Uplift force
Wall

Nodules

ResistanceResistance

Obayashi Corporation

Winter 2010

Obayashi Corporation

Spring 2011
13 Construction of World-class Tower

Obayashi Corporation

Building Construction

Tokyo Sky Tree
— High-strength Steel Pipe for Antenna Tower —In building the steel tower known as theTokyo Sky Tree®, two grades of highstrength steel pipe are seeing extensive
use―400 N/mm2 grade and 500 N/mm2
grade. In addition, for the topmost antenna
tower, steel pipes for building structures
having a strength rating of 780 N/mm2, thehighest in Japan, have been adopted. Thisis the first instance in Japan of 780 N/mm2
grade pipe having a maximum wall thickness of 80 mm being applied in the construction of an architectural structure. Ta-

ble 1 shows an outline of these steel pipes.
The dimensions of the steel pipe thus
adopted are 500~2,300 mm in outside diameter and 19~100 mm in wall thickness.
The steel pipe used for the lowest sectionof the tower is 2,300 mm in outside diameter and 100 mm in wall thickness.

Table 1	Outline of High-strength
Steel Pipes
New pipe spec.

0.2% offset proof
stress (N/mm2)

630 N/mm2 grade 630 or more
500 N/mm2 grade 500 or more
400 N/mm2 grade 400 or more

Production Processes for Highstrength Pipes
The high-strength steel pipes are manufactured by means of the UOE, press-bending

JIS G 3475
STKN490B

325~475

or roll-bending process.
Examples of these processes are shown in
Figs. 1 and 2.
  In the UOE process,Steel plate
Edge cutting and bevelingsteel plates are cut to the(plainer or milling)prescribed sizes andsubjected to bevel fabrication. Following this,Tack welding
the plates are formed
U-press
O-press
into a U-shape using a
U-press and then into an
O-shape using an OPipe edge
Inside andTab
Pipe edgepress. Next, the bevel
Shipment
Inspection
chamfering
outside welding
attachment
chamfering
section is cleaned andtack welding is conduct(Mechanical or hydraulic expander)
ed. The seams of Oformed materials are
weld-joined from bothFig. 2 Roll-bending or Press-bending Pipe-making Process
the outside and inside by means of submerged arc welding, and the pipe thus manufactured is finished to the prescribed size
using a mechanical expander. (Refer to Fig.
1)
The roll-bending and press-bending
Steel plate
Automatic gas cutting
processes are primarily used when the steel
pipes have wall thicknesses or outside diameters that are too large for other processes. As shown in Fig. 2, a bevel is fabricatedInside and outside
Tack weldingon the edges of the steel plates, and after
surface weldingedge bending using a press, the plates are
Press winding
formed into a perfect cylinder using a rollEdge bending press
er or press, and the seam is weld-joined bymeans of submerged arc welding to proRoll winding
duce the pipe. A cold, warm or hot forming
process is adopted depending on the wall
Material pipe
Pipe edge
Shipment
Inspection
Complete roundinspection
chamfering
thickness and outer configuration.

Fig. 1 UOE Pipe-making Process

High-strength Steel Pipes 14

tures and reduction patterns during plate
rolling and by adjusting the cooling method immediately after rolling as necessary.
Fig. 3 shows TMCP in JIS. The four major
integrated steelmakers in Japan have developed their own proprietary TMCP, as
shown in Table 3.
In addition to high strength, TMCP cansecure high toughness (base metal andwelds), which is normally incompatible
with high strength. Further, TMCP allows
the production of steel plates that are suitable for welding operations conducted highSteel Plates for High-strength Pipes
The steel plates used for high-strength pipe
making are produced by forecasting thechanges that are likely to occur in the material properties of the plate during the pipemaking process. These plates are producedby means of TMCP and heat treatment thatuses high-performance furnaces.
TMCP (thermo-mechanical control process) is also called the thermo-mechanicaltreatment process. It is a process that produces plate with the optimal material properties by controlling the rolling tempera-

above the ground by improving weldability, e.g. welding at low preheating temperatures.
These excellent performances not only
meet the needs of high-rise and large-spanstructures but also allow for smaller crosssections and thinner wall thicknesses in the
structural members. This, in turn, contributes to greater aesthetic freedom in building construction and structural design, andto greater economy by reducing transportand fabrication costs and by shortening theon-site construction term.

Fig. 3 Thermo-mechanical Control Process for Plate Rolling (JIS G0201)
Thermo-mechanical control

Conventional
controlled rolling

Temperature
Thermo-mechanical rolling

Accelerated cooling

Ordinary heating
temperature ofsteel piece

R
R

R

R
R

Normalizing
temperature

R

R

R

R
Region for not-yet
crystallized structure

R

R

R

R

R

Ar3
Ac

Ar1

Ac

R: Under pressure Ac: Accelerated cooling

Table 3 Steelmakers’ Own TMCPs
Maker

Abbreviation

Own process

Nippon Steel

CLC-μContinuous on Line Control
Process-μ

JFE SteelSuper-OLAC

Super On-line Accelerated
Cooling

Sumitomo
MetalsDAC

Dynamic Accelerated
Cooling

Kobe SteelKCLKobe Steel’s Controlled
Rolling and Accelerated
Cooling

Large-diameter, heavy-thick high-strength steel pipes destined for the construction of Tokyo Sky Tree
15 High-strength Steel Pipes

Building Construction

CFT Columns— High-strength Steel-Concrete Composite Column
Members —By Atsushi Fujii, Research Institute of Technology, Konoike Construction Co., Ltd.
Tooru Hirade, Takenaka Research & Development Institute, Takenaka Corporation
In the R&D project introduced in “New
Structural System Employing Innovative
Structural Materials,” a special feature inissue No. 29 (October 2009) of Steel Construction Today & Tomorrow, studies weremade of CFT (concrete-filled steel tube)
columns that use both high-strength steel
and high-strength concrete. Specifically,
experimental surveys were conducted toconfirm the structural characteristics of
CFT columns with regard to existing structural design equations.
A major target in the R&D project discussed in “New Structural System Employing Innovative Structural Materials”
was to establish a steel-structure building
system using innovative structural materials capable of ensuring that the main frameof a building could remain within its elastic
range even during earthquakes with a seismic intensity of 7 (the highest seismic level of the Meteorological Agency of Japan).
The performances required of the new steel
materials to be used in this new structural
system include enhanced resources savings, a reduced environmental burden, andhigher seismic resistance. In other words,
the goal of the project was to develop steelbuildings featuring a safe structural system
and a long service life.
New 800 N/mm2-grade SteelIn order to realize the framing required by
the new structural system, the appropriate
application of high-strength steel products
is needed. Because the structural skeleton
remains in its elastic range, it is not necessary to maintain strict application conditions for plastic range, such as the yield ratio. Accordingly, by capitalizing on highstrength, it is possible to reduce steel usage
and structural weight, thereby leading tolower costs.
Specifically, a steel framing system inTable 1 Outline of Specifications for H-SA700 Steel Products
GradeApplication

Plate
thickness
t
(mm)

YS
(N/mm2)TS(N/mm2)

YR
(%)

6~50

700~900 780~1000 ≤98

H-SA700A Non-welding use
H-SA700B

Welding use

Impactproperties

Mechanical properties
EL
(%)

vE
(J)

≥16
≥47 (0˚C)
JIS
No.4 ≥47 (–20˚C)

Compression axial
force Max 750 tons

Test specimen

Horizontal force

Horizontal force

Photo 1 Tests on high-strength CFT columns

which the main frame remains within its
elastic range, even in earthquakes having aseismic intensity of 7, can be more rationally realized by fully utilizing highstrength CFT columns, thereby providing
more comfortable space.
The 800 N/mm2-grade high-strength
steel that was developed in the current
R&D project for use in elastic design forseismic intensity 7 earthquakes offers twice
the tensile strength of conventional steel
products. The higher tensile strength andenvironmental friendliness offered by thisproduct were economically and rationallyattained by reducing the amount of alloying elements added and by eliminating production processes through the effective useof innovative production technologies. In
addition, the higher strength of this material lowers the environmental load by allowing a reduction in the use of steel products. Table 1 shows an outline of thespecifications for 800 N/mm2-grade steel
products (H-SA700A and 700B).
High-strength CFT Columns 16

shape and material properties of the corner R section (Fig. 2).
High Cyclic Fatigue Performance ofHigh-strength CFT Columns
Because CFT columns are expected to see
long-term use, experimental surveys were
made, one, regarding changes in structural
performance in the elastic range by obtaining multiple repetitive responses during
small/medium earthquakes and strong
winds and, two, regarding changes in horizontal rigidity in respective cycles (Fig. 3).
The survey results show that the effect of
the change of horizontal and axial rigidityof CFT columns on the entire building
structure is limited.

Photo 2 Final test conditions of high-strength CFT columns

Structural Characteristics of Highstrength CFT Columns
Experimental surveys were made of thestructural characteristics of CFT columns
manufactured through the combined use of
800 N/mm2-grade high-strength steel and100~150 N/mm2-grade high-strength concrete in order to confirm their relation withexisting structural design equations (refer
to Photos 1 and 2). The following results
were obtained:● The experimental strength of CFT columns can be assessed by a corresponding
application to existing calculation methods.
● As the elastic limit (at the time of yield-ing) increases, the deformation of CFT
columns, manifested by their allowablestrength, surpasses that of ordinary steel
products.
● The constraint effect of square CFT columns can be applied only to weld builtup CFT columns.
● Under strict application conditions (large
width-to-thickness ratio, high axial
force), it is necessary to take into accountthe reduction of concrete strength (Fig.
1).
● In the case of a large width-to-thickness
ratio and loading to the 45-degree direction in the adoption of cold-formed CFT
columns, it is necessary to consider the

Fig. 1	Treatment of Value CγU depending on
Axial Force Ratio and Width-to-Thickness Ratio

Fig. 2	Treatment of Corner R Section depending on Width-toThickness Ratio

0.5

0.5

C

γ U = 0.85

Axial force ratio

Axial force ratio

Applications of New Structural
Technologies and Materials
Applicability of the new structural system
was proven by testing five applications thatmost fully utilize the system’s characteristic features. Of these five applications,high-strength CFT columns were used in
an applicability study conducted in a seismic-resistant medium-rise office building
built at the periphery of an urban center(Fig. 4).
In the building, cores were located on
both sides of the building, into which vibration-control braces were strategicallyarranged to treat most seismic forces. Highstrength CFT columns were arranged at thebuilding’s center, and slender high-strength
steel columns were positioned at the building’s outer periphery. As a result, a 22 mwide open space with high flexibility was
secured. (Refer to Fig. 5)

0.25

C

Considerations forcorner R
sectionγU=1

23
Width-to-thickness ratio
17 High-strength CFT Columns

0.25

No
considerations forcorner R‫ޓ‬
section** In the case of
45˚-direction
loading, it isnecessary to pay
due considerations
to the shape andmaterial propertiesof corner R
section.

30

23
Width-to-thickness ratio

30Building Construction
1.10
1.05
Horizontal rigidity deviation rate

Fig. 3	Relations between Horizontal Rigidity
Reduction Rate and Number of Excitation Cycles of High-strength CFT Columns

R=±1/400

1.00
0.95
Specimen 1
Specimen 2
Specimen 3
Specimen 4
Reference point ofdeviation rate

0.90
0.85
0.80
0.75

R=±1/250

R=±1/150
Development of low axialforce tube HAZ cracking

0.70
0.65
1

10

R=±1/150
Development oftube HAZ
cracking

N≒5000 N≒20000
100
1000
10000
100000
Excitation cycle (number)

Fig. 4	Appearance of Highly Seismic-resistantMedium-rise Office Building to Be Built
in the Periphery of Urban Center Employing the New Structural System

Fig. 5	Composition of Structural Systems
Adopted for Highly Seismic-resistantMedium-rise Office Building

High-strength CFT column

Outer periphery: Slender high-strength steel column(dia.: 300 mm)

Side core section•Framing by use of high-strength steel•Vibration-control brace damper•Ring socket column connection

Office floor section•High-strength CFT column•Slender high-strength steel column•Ring panel method
High-strength CFT Columns 18

JISF Seminar in Jakarta and Hanoi

Southeast Asia Steel Construction
Seminar for 2010
The Committee on Overseas Market Promotion of the Japan Iron and Steel Federation (JISF)
has held the Southeast Asia Steel Construction Seminar since 2002. The major aim of theseminar is to promote a wider range of applications for steel structures and to develop markets for Japanese steel products in Southeast Asian nations, where improvements in social
infrastructure are actively being promoted and the demand for steel civil engineering products is increasing.
In 2010, the seminar was held in Indonesia and Vietnam with extensive cooperation andsupport from government officials and academics involved in steel construction and fromthe Japanese Embassies located in the two nations as well. Specifically, the seminar washeld in November 2010 in Jakarta and Hanoi and was centered on lectures citing examplesof bridge and port/harbor construction and on the attainments of research on corrosion
and corrosion protection. Outlines of the seminar are introduced below:
Outline of Jakarta Seminar● Date (venue): November 9, 2010 (Hotel Grand Hyatt Jakarta)● Participants: 130 from government and academic fields, fabricators, design companies,
construction companies● Lectures: Seven themes (four from Japan, three from Indonesia)— “Steel Bridge Maintenance in Japan” (Prof. Masatsugu Nagai)— “The Infilled Steel Concrete Structure for Health Sciences Faculty in University of Indonesia” (Dr. Henki W. Ashadi)— “Recent Development in Indonesian Railway Steel Bridges” (Dr. Heru Purnomo, Mulia
Orientilize, M.Eng)— “The Need of Steel Bridges Maintenance in Indonesia” (Mr. Herry Vaza)— “Current Topics of Steel Structures In Tokyo Bay” (Prof. Osamu Kiyomiya)— “Life Extension of Steel Structures by Corrosion Prevention Technology — Especially Portand Harbor Steel Structures” (Prof. Hidenori Hamada)— “New Seismic Design for Port & Harbor Structures” (Prof. Osamu Kiyomiya)
Outline of Hanoi Seminar● Date (venue): November 12, 2010 (Hotel Hilton Ha Noi Opera)● Participants: 110 from government and academic fields, fabricators, design companies,
construction companies● Lectures: Six themes (three from Japan, three from Indonesia)— “Design Codes and Construction Trend on Steel-concrete Composite Bridges in Japan”(Prof. Masatsugu Nagai)— “Evaluation of Loading Testing Results on Can Tho Cable Stayed Bridge (Prof. Dr. Nguyen
Viet Trung)— “Applications of Steel Construction in Transportation Engineering in Vietnam (Mr. Nguyen Trung Hong, Mr. Tran Quoc Bao)
— “Design & Construction of Port Structures by Steel Piles” (Prof. Osamu Kiyomiya)— “Some Applications of Steel Construction in Bridge Engineering in Vietnam” (Dr. DO Huu
Thang and Mr. BUI Xuan Hoc)
— “Life Extension of Steel Structures by Corrosion Prevention Technology — Especially Portand Harbor Steel Structures” (Prof. Hidenori Hamada)Seminar scenes
19 JISF Seminar in Jakarta and Hanoi(Jakarta) (Hanoi)1

Steel-frame Structure: Technological
Trends and Development

Special Feature
Tokyo Sky Tree3
Creation of a Landscape beyond
Space-time
5
Structural Outline of Terrestrial Digital Broadcasting Tower
10 Construction of World-class SteelTower
14 High-strength Steel Pipe for Antenna
Tower
16

High-strength CFT Columns

COVER
Artist's sketch of Tokyo Sky Tree upon completion

A magazine 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
Chairman: Eiji Hayashida
URL http://www.jisf.or.jp
Japanese Society of Steel Construction
Yotsuya Mitsubishi Bldg. 9th Fl., 3-2-1 Yotsuya,
Shinjuku-ku, Tokyo 160-0004, Japan
Phone: 81-3-5919-1535 Fax: 81-3-5919-1536
President: Koichi Takanashi
URL http://www.jssc.or.jp
Editorial GroupJISF/JSSC Joint Editing Group for Steel Construction Today & Tomorrow
Editor-in-Chief: Tetsuya Akahoshi
The Japan Iron and Steel Federation● Beijing Office
Room 2206, Jingtai Tower, 24 JianguomenwaiStreet, Chaoyang-District, Beijing 100022, China
Phone: +86-10-6515-6678
Phone: +86-10-6515-6694
STEEL CONSTRUCTION TODAY & TOMORROW ispublished three times per year to promote better
understanding of steel products and their application in construction field and circulated to interested executives and companies in all branches of trade, industry and business. No part of thispublication can be reproduced in any form without permission. We welcome your comments
about the publication. Please address to Lettersto the Editor.