No. 63 December 2021

STEEL CONSTRUCTIONTODAY & TOMORROW

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

Feature Article

Towards Promotion of
Steel-structure Constructionof Public Buildings
1 Steel Supports the Future

Construction of Public Buildings

3 Optimized Use of Features Peculiar
to Steel Structures

6 Trial Design and Cost Comparisonof Steel-structure School Building

7 Verification of Habitability of
Steel-structure Buildings

11 Outstanding Examples in Public Building Construction
Employing Steel Structures

Serial Article: Latest Design of Steel Buildings in Japan (6)Shibuya Station on theTokyo Metro Ginza Line
15 Column-free Subway

Station Building Constructedby the Use of 45
Continuously-arranged
M-shaped Steel Arches

Published Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel Construction

Feature Article: Towards Promotion of Steel-structure Construction of Public Buildings (1)Steel Supports the Future Constructionof Public Buildings
Emerging Tasks Involved in Public Building Construction

Superannuating Public Facilities
and Steel Structures
A pressing task is emerging in Japan-theissue of the ongoing superannuation of social infrastructure constructed in the higheconomic growth period in the 1960s, andappropriate measures to cope with such asituation are required to be promptly implemented. In particular, schools, government
offices, hospitals and other public buildings
are undergoing remarkable superannuation,and public buildings constructed during
the period from the late 1960s to the early
1970s have entered into the renewal stage.
In Japan, most non-residential buildings
are constructed with steel structures. On
the other hand, reinforced-concrete (RC)structures have been adopted for the construction of most public buildings, particularly school buildings. However, steelstructures are increasingly being adopted in
the construction of public buildings due tochanges in societal environments such as:• Need for new facility improvement measures with which building space and application can flexibly be changed so as to meetchanges in population movement in the future and building function to be required• Remarkable shortage of skilled workers engaged in RC construction, suchas those working in reinforcing bar arrangement and form assembly
Steel structures can redundantly resist
earthquakes, and because the structure iscomposed of stable-quality structural members manufactured and fabricated at shops,
it can be said that steel structures are suitable for the construction of public buildings
for which high seismic safety is required.

Steel Industry Initiatives for theWider Application of Steel Structures
The Japan Iron and Steel Federation (JISF)
established in 2014 the Committee on the
Promotion of the Steel Construction of Public Buildings, which has so far extended extensive efforts for promoting steel-structure
application in the construction of schools,
hospitals, and other public buildings wheresteel-structure application levels have been
low. Under collaboration with the Japan
Steel Fabricators Association, JISF has distributed steel-structure promotional brochures to local governments, design offices and general contractors nationwide andhas held related courses for them (Photo 1).
In addition, JISF has established the Subcommittee on the Survey and Research on
Public Buildings Employing Steel Structures within the Japanese Society of Steel
Construction. Learned persons in the field ofbuilding plans, particularly of living environments, those working in practical design andconstruction and researchers of design andconstruction companies have participated in
the Subcommittee, which has conducted surveys and research on the following subjects:• Analysis of the specific performance of steel

Fig. 1 Societal Conditions and Needs Surrounding Public
Facilities
Enhanceddisasterprevention
measureFinancial
restrictions

Ongoingsuperannuation
Current
state ofpublicfacilities

Societalneeds
Elimination/
consolidation,
reorganization
Gender-equal
society• Welfare facility(Day nursery)

Globalenvironmentprotection measure• Countermeasureagainst global warming• Effective utilizationof resource• Reduction ofindustrial waste
Local community• Social training
facility• Sport facility(Library, child hall,public hall)Decreasing birthrate
and aging society• Welfare facility• Sport facility(Health facility, daily carecenter for the aged)

1 Steel Construction Today & Tomorrow December 2021

Photo 1 Course to promote steel-structure
application held by JISF

structures vis-à-vis the function required for
public buildings, and the trial calculation of
construction costs employing trial designs• Survey of the noise-, vibration- and thermalinsulation performance of steel structures
involved in the living environment, and theexamination of points of cares to be givenin the design of steel-structure buildings
New Functions and Requirements
in Public Building Construction
While many public facilities have enteredinto the renewal stage, societal conditions
surrounding public buildings show radical
changes, and the function and application
required for these buildings are diversifying
and becoming more sophisticated. It is required for public facilities to function as not
only a core operating base but also a disaster prevention base for people living in thelocal community. On the other hand, the recent financial restrictions imposed on local
governments call for less maintenance andconstruction costs and longer service life
for public facilities. (Refer to Figs. 1 and 2)

Fig. 2 Functions Required for Public Facilities to Possess
and Tasks Requiring Further Examination
Applications

SchoolFunctions required Functions required in
the event of disasterin usual time

• Safe and secure• Evacuation facility • Response to
place
for those living inchange in• Core facility in the neighboring areas student number
regional communityand population
Complex use as
movement
public hallOpening ofgymnasium andlibrary• User-friendly andease-of-use
facility
Government • Suppression ofequipment andofficerunning costs

Hospital

Tasks requiring
examination• Response to• Response tobusinesschange incontinuity
population
program (BCP)
movement• Disaster response (change of service
headquarters
to be required)• Response to• Safe and secure• Replacement of
medical equipment;
businessplace
continuity program response to aging• Comfortablesociety andspace for patients • Accommodation
reforming of system
of mass injured• Building plan that
(response topersons
is high in working
increase/decrease
efficiency and easyof sickbed number)in working for staff

Steel Solutions Conducive to Dealing with Emerging Tasks in Public Building Construction

For public buildings, there is a call for functions that can appropriately meet changing
societal needs, and certain tasks to copewith such a need are becoming apparent.
In dealing with such emerging tasks, characteristic features peculiar to steel structures may serve as an effective solution.
Given such situations, JISF’s Committee on the Promotion of Steel Constructionof Public Buildings has recently publisheda revised steel-structure promotional brochure titled “Steel Supports the Future
Construction of Public Buildings” (Photo2). It assesses the role and performance ofsteel structures conducive to solving thesetasks as seen in the following:

Optimized Use of Features
Peculiar to Steel Structures• Response to Complex Use andApplication Change
It is required for public buildings to promote effective facility operation for complex uses and to flexibly meet changing
needs. Steel structures can secure wider space with less column installation.
Flexible space can be created by the useof steel structure.
• Reduction of Construction Termand Cost
In the construction of public buildings,
shorter construction periods and the reduction of construction cost and maintenance cost are important requisites. Steelstructures can reduce the construction
term over RC structures.
• Provision for Disasters
It is required for public facilities to function as a disaster-prevention base in theevent of disaster. Steel is a material high intoughness, strength and ductility. Seismicenergy is absorbed by steel’s own deformation capacity to prevent the collapse ofbuildings. Steel structures are suitable forthe construction of the disaster-prevention
base (evacuation site) for which high seismic safety is required to be provided.
• Reduction of Environmental Load
Environmental friendliness is an important element required for public buildings. Steel can be recycled without construction waste. Steel is an eco-friendly
material that allows reuse.
(Refer to Fig. 3)

Trial Design and Cost Comparisonof Steel-structure School Buildings
Trial design was made for school buildings
employing steel structure and RC structures to compare the construction cost between these two structures. It was learned
from the trial design that the total cost of
steel structures was cheaper than that of RC
structure due to a sharp reduction of foundation pile work costs caused by the lightweight construction of the upper structure
and to the reduced on-site management
costs caused by the shorter construction
term. Further, it was also learned that interms of the maintenance cost, steel structures were preferable over RC structures.
Verification of Habitability of
Steel-structure Buildings
Some project owners and designers havefears that the sound-insulation and vibration-damping performance of steel structures are inferior to those of RC structures.
Targeting school buildings employing steel
structures and RC structures, sound insulation and vibration damping were surveyed.
Further, assuming the school building, theFig. 3 Keywords for Public Building Construction in the Coming Generation
and Features of Steel Structures
KeywordFeatures peculiar tosteel structures• Response to complex use andsocietal changes and needs• Creation of flexible space• Affluent architectural design• Reduction of construction term
and cost• Stabilized quality and shorter
construction term brought about
by the use of shop-manufactured
steel frame members• Provision for disasters• Steel-structure buildings resistantto earthquakes, tsunamis andother disasters• Mitigation of environmental loads• Steel product-Eco-friendly
materialsound environment and temperature/thermal environment were analyzed.
• Survey of Sound Environments
Targeting primary school buildings employing steel-structures and RC-structures, the floor impact sound insulation
performance was measured. Becauseof the difference in floor specifications
subjected to surveys, a simple comparison between these two structures could
not be conducted, but it was confirmedthat the steel structure offered the floor
impact sound insulation performance required for classroom floors.
• Analysis of Heavyweight Impact
SoundsThe vibration response of steel-structure
and RC-structure models was analyzed.
No clear difference between them wasrecognized.
• Analysis of Walking Vibrations
Walking-simulated vibration was analyzed. It was confirmed that both steel
structures and RC structures have enoughhabitability to resist walking vibrations.
• Analysis of Annual Thermal Load
Assuming a 3-story school building, thethermal load imposed on steel-structure
and RC-structure models was calculated. No remarkable difference of air-conditioning load between them was recognized, and further it was confirmed thatthe structural difference did not materially affect the air-conditioning load.

Outstanding Examples in Public
Building Construction Employing
Steel Structures
Main reasons why steel structures are adopted are as follows:• Realization of column-free open space• Feasible lightweight construction becauseof unstable ground conditions• Reduction of construction term
• Reduction of construction cost
• High compatibility with timber materials♦♦♦

How steel structures can contribute to the future
construction of
public buildings
is introduced in
more detail in thefollowing pages:

Photo 2 Steel-structure
promotional
brochure
December 2021 Steel Construction Today & Tomorrow 2

Feature Article: Towards Promotion of Steel-structure Construction of Public Buildings (2)Optimized Use of Features Peculiar to
Steel Structures
Response to Complex Uses
and Application Changes

For public buildings in the coming generation, there is a need to meet diverse
needs and functions, among which are:
Efficient Improvement of Public
Facilities Capitalizing on Complex
Uses
Schools and other similar public facilities have so far been prepared for single application purpose. However, fromthe viewpoint of financial restrictions,improved convenience for the community and effective land utilization, it isrequired to efficiently prepare public facilities that capitalize on complex uses.
(Fig. 1)
Flexible Response to Changing
Needs
Due to the declining birthrate and ongoing aging society and the trend toward
more compact living spheres in the community, the population and age composition are showing steady changes, which
poses new requirements for public buildings-building structures that allow not
only flexible changes in internal layout and application but also efficient use
over the long term.
Column-free Wide Space andFreedom in Room Layout
A notable feature of steel-structure buildings lies in their wide spaces with lesscolumns. For facilities required to provide wide open spaces, it can be said
that steel structures are the appropriate

structural system. Because of less structural restrictions such as no installationof fixed walls (bearing wall) in steelstructure buildings, it is possible to design free plane plans with the use of steel
structures. In addition, when movablepartitions are adopted in steel-structurebuildings, it is easy to change the roomlayout.(See Photos 1 and 2)
Long Service Life-oriented Facilities to Flexibly Meet Changes inApplication and Layout
In common steel-structure buildings, thewall members do not bear the structural
strength. Because of this, the wall can beremoved or installed in conformity withchange in future needs and without damaging the structural members, and accordingly the building application androom layout can easily be changed.
In short, steel structures are a structural system that allows the construction of“long service life-oriented public facilities” for which efficient utilization overthe long term becomes feasible.
Securement of Effective SpaceOne of the attractive points in steelstructure buildings is the narrow sectionof columns. That is, even in an identicalfloor area, as the area occupied by columns is narrower, the applicable building space increases.
Further, because of the low heightof steel beams, it becomes possible
to secure the required ceiling height
while suppressing an increase of story height or settling the story height
to a low level.

Affluent Architectural Design
Because wide openings can be provided
with the use of steel structures, bright,
open indoor spaces can also be provided. Further, high workability peculiar
to steel structures can offer diverse architectural designs such as fine curving and hybrid use with timber (Photo3) and other locally produced structural members.

Photo 1 Column-free working room found in asteel-structure building
Movablepartition

Corridor

Photo 2 Classroom layout change employing
movable partitions

Fig. 1 Image of Complex Facility Building of Public Function-intensive Type

Local community exchangearea (public hall, etc.)

Gymnasium(sharing between school
and community)

Library(sharing between school
and community)
Junior high school
Primary school

3 Steel Construction Today & Tomorrow December 2021

Photo 3 Timber-steel hybrid structural member(fireproof member is put into practical use)
Source: Japan Laminated Wood Products
Association

Reduction of Construction
Term and Cost

In the construction of public buildings,
an important issue is the reduction of
construction costs.
Because steel-structure members are
shop-manufactured, their quality is stable. In
addition, it can be expected for the steel structure to reduce on-site construction term andconstruction cost. On top of this, less on-site
work brought about by the reduced construction term also leads to the mitigation of various loads imposed on those living in neighboring areas and users.
Stable Quality Obtained from
Industrial Production
Because of the shop manufacture and fabrication of steel structural members, their quality is stable. The steel structure is assembled
at the site by means of bolt fastening andsimple welding, and thus the building quality is not apt to be governed by the skill level of on-site workers, which thus allows thestable construction of high-quality buildings.
Reduction of Construction Termdue to Reduced On-site WorkIn the construction of RC-structure buildings, reinforcing steel bars are arranged at

the construction site and concrete is poured
into the form to erect the building structure floor by floor. In contrast, in the construction of steel-structure buildings, steel
structural members shop-fabricated in advance are carried into the construction site
to assemble the building structure, which
thus does not require complicated on-site
work. Accordingly, the construction work
can be proceeded without impacts from ashortage of labor or weather conditions,which thus allows the reduction of construction terms. (Refer to Figs. 2 and 3)

involved in construction site management.
Reduction of Construction Costs
One of the structural features brought
about by the use of steel structures is thepossibility for the lightweight construction of the upper building structure, whichallows a sharp reduction of construction
costs including piling work costs whencompared to RC structures. In addition,
the steel structure allows the reduction of
on-site management costs due to the reduced construction term. (Refer to Fig. 4)

Reduction of Maintenance Costs
Mitigation of Diverse Loads
The exterior walls of RC structures are notaround Construction Site
Because of the reduced on-site work, the maintenance-free, and periodical mainteemission of dust and waste materials and nance is required to prevent the neutralization of concrete. On the other hand,occurrence of noises can be prevented.
Because of this, when construction the application of highly-durable exterior
work is promoted at sites close to residen- walls in steel-structure buildings can suptial areas, the mental burdens imposed on press maintenance costs to a low level.
residents around thesite can be mitigated. Fig. 3 Comparison of Construction Term between Steel
Structures and RC Structures
Further, the usage(Example of Medium-rise Building)term of the land andSteel structureparking lot around
Earth Earth work Abovegroundthe construction siteretainingandskeletonand piling foundation construction
can be shortened,
Inspec- Reduction
Finishing workbywhich leads to thetion 2 months
reduction of the cost

Fig. 2 Reduction of On-site Work
Steel structures

RC structures

Steel frames are shop-fabricated inadvance, and fabricated frames arecarried into the construction site andassembled at the site, which requires
no complicated on-site work.

Reinforcing bars are arranged at
the construction site and concrete
is poured into forms to erect thebuilding structure one story by
one story.

1 m. 2 m. 3 m. 4 m. 5 m. 6 m. 7 m. 8 m. 9 m. 10 m. 11 m. 12 m. 13 m. 14 m.
m: month(s)Earth Earth work Aboveground skeleton
retainingandconstruction
and piling foundation
Finishing work
RC structure

Fig. 4 Comparison of Costs between Steel Structures and
RC Structures
12
monthsSteel frame erection

On-site reinforcing
bar arrangement

Provisions for Disasters

For government offices, hospitals, andother public facilities, there is a need tofunction as a disaster-prevention base(evacuation site) in the event of disaster,and thus it is necessary to take possiblemeans to handle earthquakes and tsunamis. Steel structures support the construction of public facilities that are highly resistant to disasters.
Provisions for Earthquakes
Steel structures tenaciously resist seismic
vibration. Steel is a structural material that is high in toughness, and thus theInspection

14monthsMaterial cost: On-site work amount: Construction term:
Steel structure
Steel structure
Steel structure> RC structure< RC structure< RC structure

seismic energy is absorbed capitalizingon the optimum use of its own deformation capacity, which thus prevents thecollapse of buildings.
In order to further improve the seismic
safety of steel-structure buildings, building
vibration is reduced by the use of vibrationcontrol dampers (buckling-restraint braces,etc.) and isolators (laminated rubber, etc.),
which also allows the mitigation of damage to columns and beams (Photo 4). Steelstructures are a structural system suitable
for the construction of disaster-prevention
bases requiring high seismic safety.
Another advantage of steel-structure

Cost
reduction

application is easy maintenance after being subjected to earthquakes. In steel structures, structural members and finishingmembers (exterior wall, etc.) are separately installed, and thus maintenance work
can more easily be implemented compared to the repairing of cracks that occur

Photo 4 Example of base isolator
December 2021 Steel Construction Today & Tomorrow 4

in RC structures (Photo 5). Steel structures
allows the mitigation of repair costs.
As a measure to handle seismic force,base-isolation steel-structure buildings
are increasingly being constructed. Because the steel structure is light in weight,
the number of base-isolation devices tobe installed can be decreased. Base-isolation devices are high-priced members, andwhen the installation number is decreased,
the building construction cost can be reduced by a wide margin. (Refer to Fig. 5)

Provisions for Tsunamis
Based on the survey results of damage in
the Great East Japan Earthquake, technical standards concerning tsunami evacuation buildings were established in 2011.

With their establishment, it has become
possible to design tsunami evacuationbuildings employing steel structures.
(Refer to Figs. 6 and 7, and Photo 6)

Fig. 5 Seismic-resistant Building Construction
Seismic-resistant structure

Vibration-control structure

Base-isolation structure

Vibrationcontrol
damperDamperIsolator
Vibrations

Vibrations

Vibrations

Fig. 6 Calculation Method for Tsunami Wave Pressure
Tsunami wave pressure is calculated as the static hydraulic pressure with a height
Tsunamiobtained by multiplying design inundation depth h by water depth coefficient a.
wave
a: Water depth coefficient
p: Unit volume mass of water (t/m3)
h: Design inundation depth (m) g: Gravity acceleration (m/s2)
ah pressure

Shielded

Not shielded

Distance from500 m Less than No relation
shore or river bank or more 500 m with distancePhoto 5 In RC-structure walls, cracking andconcrete peeling are apt to occur inthe event of earthquake.

Water depth
coefficient a

1.5

2

h

3

apgh

Fig. 7 Example of Design of Seismic- and Tsunami-resistant Reinforcement of
Existing RC-structure School Buildings using Steel Structures

Outline of building• 3 stories aboveground; Total floor area of 2,005 m2
Outline of reinforcement• Additional installation of steel-frame withsteel braces on peripheral section of existing
school building• Installation of steel-structure evacuation stage
by taking into account application as tsunami
evacuation facility• Support of evacuation stage by the use of steel
tube column newly installed at peripheral sectionof existing building• New installation of screwing pipe piles aiming at
overturning prevention, sliding prevention, bracepull-out resistance and load support of evacuation stage

Mitigation of Environmental
Loads

Today it is required for public buildings
to be “eco- and human-friendly facilities.”
The human-friendliness (barrier free), thenecessity to pay due consideration to theperipheral environment and other requirements described in the specifications caneasily be solved at the structural design
stage. Then, what should happen to publicbuildings after they finish their service life?
Steel-Ultimate Eco-friendly
Material
For buildings to be built in the future, it isrequired to pay due attention to the lifecycle
cost (cost covering from building construction and maintenance to demolition and disposal). Far before the term “eco-friendliness” spread in society, steel has properly
been recycled for reuse. Steel is an outstanding structural material in terms of recycling.
5 Steel Construction Today & Tomorrow December 2021

Outdoor evacuation
stairway

Evacuationstage

Evacuation
balcony

Steel-frame
brace
Steel tube
columnPhoto 6 Mitigation of tsunami
external force by means
Source: Japanese Society ofof the installation of
Steel Construction
pilotis at low-rise section
Steel pipe pile with tip wingof building• Reduction of Construction

Towards realizing a “sustainable society for the coming generation” from the“scrap and build society” we have experienced, steel structures support the construction of long service life buildingsthat can flexibly meet even changes inapplication in the future.

• Saving of Resources

Fig. 8 Conceptual Diagram of Steel
Recycling from Construction
WastesLimestone

Waste Emissions
Because steel products can be recycled, noconstruction waste is emitted, which leads
to the reduction of waste treatment costs.
Steel is conducive to solving a pressingtask, the shortage of waste disposal sites.

Steel is an ultimate eco-friendly material that can be reused repeatedly by meansof decomposition and regeneration of recycled steel products. The steel industry does not waste iron, an important resource presented from the earth. (Fig. 8)• Long Service Life Buildings
Among notable structural advantages derived from the use of steel structures are thelarge-span construction and no need for seismic-resistant walls. It can be said that steel
structures are the structural system mostsuitable for the renovation of buildings.

Iron
ore

Coal

ConcreteBlast
furnaceSteel scrap
Steelproduct

Electricarc
furnaceContinuous
casting
Refining

Converter

Feature Article: Towards Promotion of Steel-structure Construction of Public Buildings (3)Trial Design and Cost Comparison of
Steel-structure School Building

Fig. 1 3rd-floor Framing Plan

Atrium8.1m

Fig. 2 Framing Elevation (span direction)
4.0m

Multi-purpose
hall (atrium)

4.0m
4.1m

10.8m

10.8m

10.8m

Table 1 Comparison of Cost between Steel Structures and RC Structures(¥1,000)
Item
Steel structure
RC structure
271,342
Building structure
238,364□-500×16-22 (BCR295)□-800×900~□600×1150 (Fc30~33)
Column□-600×950~□-650×1150 (Fc30~33)
H-488×300~H-800×300 (SN490B)
Beam
323,072
Finishing
288,183
Exterior wall
Exposed reinforced concrete + Coating
Extrusion-formed cement board
Gypsum board with lightweight steel beds
Interior(Exterior wall section: Spraying of thermal insulation material*)
wall
Window
Double-layer glass
Fire protection―
12,371(sprayed rock-wool)
24,277
27,100Earth work
83,000156,000
PilingCast-in-place
Φ1600~1900
Φ2000(L=29 m)681,084
742,625
Total cost
*Additional cost reduction due to reduced construction term can be expected for the steel structure.

Outline of Building Structure• Longer span (8.1×10.8 m) than the span ofgeneral school buildings and moment-frame
structural type by takConstruction Cost (Initial Cost)
ing into account future Fig. 3Building
structure Fire protection
application change
Finishing
Earth work
Piling• Safety coefficient as 800,000
700,000
a disaster-prevention
600,000
base: 1.25; Structural
500,000
400,000
calculation: Route 3300,000
Foundation
pile
type:
•
200,000
Cast-in-place con100,000
crete pile (L=29 m)
0
Steel structure RC structure(Figs. 1 and 2)
Construction cost (¥1,000)

Photo 1 Appearance perspective of steel-structure
school building

Fig. 4 Maintenance Cost

Calculation conditions• The durable year is set at 60 years, andmaintenance is carried out every 15 years.
• The exterior wall of steel structures issubjected to partial repair (20%), and thatof RC structures is recoated every 15
years. The sealing material used for both
structures is replaced every 15 years.
• As regards the interior, waterproof layer
and other sections, identical maintenanceis carried out for both structures.

Maintenance cost (¥1,000)

Outline of Building Plan
Total floor• 4 stories aboveground;area: 4,963 m2• Ordinary classrooms: 12 classes(4 classes × 3 grades)
Exchangeof students between grades and•utilization by local communities by providing an atrium space on the 2nd floor(installation of a stair that can enter directly into the 2nd floor)
Installationof top light on the 2nd-floor•
atrium to utilize natural light• Adoption of highly-durable extrusionformed cement board for exterior wall
Applicationof rooftop as an evacuation space•(Photo 1)

Comparison of Cost between
Steel-structure and RC-structure
Buildings
Targeting the trial design of the steelstructure school building (4-story building with a total floor area of 4,963 m2)
introduced above, the construction costin the case of adopting both the steel
structure and the RC structure was compared.
The building construction cost was low
for the steel structure that could sharply reduce the piling work cost due to lightweight
construction of the upper building structure. Even for the building requiring no piling work, because it can be expected for the
steel structure to reduce the construction
term by about 2 months over the RC structure, the steel structure was lower than the
RC structure in terms of the total cost. In
addition, because the section of the structural members to be applied could be madesmaller in the steel structure, wider effective
space became available. (Table 1, Fig. 3)
Further, in the steel structure for which
the exterior wall material could be freely
chosen, the maintenance cost could be suppressed to a low level by the use of highlydurable exterior wall members (extrusionformed cement boards, etc.). (Fig. 4)

10.8m

In the construction of a junior highschool building to be newly constructed
due to the integration and abolishment ofexisting schools, the Committee on the
Promotion of Steel Construction of Public Buildings of the Japan Iron and SteelFederation has proposed a school building employing a steel structure.
The proposed school building can flexibly meet future changes in both student
numbers and application capitalizing on thesteel structure. Further, due consideration
has been given to the complex use of theschool building as not only a disaster-prevention base in the event of disaster but alsoa facility for the use of local communities.
Based on this proposition, the Subcommittee on the Survey and Research on Public Buildings Employing Steel Structures of
the Japanese Society of Steel Construction
has made a trial design of this steel-structure school building and a trial calculationof the initial cost for the school building in
the case of adopting a steel structure or an
RC structure in its construction.

(Accumulated total)

350,000
300,000
250,000
200,000
150,000RC
structure
Steelstructure

100,000
50,000
0

15th
year

30th
year

45th
year

60th
year

December 2021 Steel Construction Today & Tomorrow 6

Feature Article: Towards Promotion of Steel-structure Construction of Public Buildings (4)Verification of Habitability of
Steel-structure Buildings

Living environments (insulation ofsound, vibration, heat and other elements) are an important factor requiredfor public buildings. Some project owners and designers seem to have fears
that the sound-insulation and vibrationdamping performance of steel structures
may be inferior to those of RC structures.
In order to promote the construction ofSurvey of Sound Environments

Aiming to understand the sound-insulation performance of the floor structures of public buildings employing steel
structures, the floor impact sound-insulation performance of two school buildings
employing steel structures and RC structures was measured.
Survey Targets
The steel-structure school building subjected to survey was as follows:• S primary school in Chiba Prefecture• Building outline: 2 stories aboveground;steel-structure public buildings, it will benecessary to wipe away such fears.
At the Subcommittee on the Survey andResearch on Public Buildings Employing Steel Structure of the Japanese Society of Steel Construction, surveys weremade of the sound-insulation performanceof school buildings employing steel structures and RC structures. Further, analysis

was made of the sound and thermal environments assuming school facilities.
As a result of surveys and analyses,
it was confirmed that there was almost
no effect of the difference by structural type on the sound insulation performance, walking-induced floor vibration
and air-conditioning load. The specificresults are as follows:

total floor area of 7,927 m2
The RC-structure school building subjected to survey was as follows:R• primary school in Chiba Prefecture• Building outline: 3 stories aboveground;total floor area of 4,934 m2

pact sound insulation of building: Part
1: Method using standard light impact
source and JIS A 1418-2 Measurementof floor impact sound insulation of building: Part 1: Method using standard heavy
impact source. (Refer to Fig. 1)

Measurement Methods
The floor impact sound-insulation performance was measured targeting thesteel-structure and RC-structure primary school buildings. The floor impact
sound was found in conformity with
JIS A 1418-1 Measurement of floor im-

Measurement Results
Because of the difference of floor specifications (double-wall floor in the steel
structure), a simple comparison could
not be made, but it was confirmed thatthe steel structure possessed the floor
impact sound insulation performancerequired for classrooms and in dealing
with both heavyweight and lightweight
impact sources (Table 1 and Fig. 2).

Fig. 1 Survey Method for Sound
Insulation Performance
Excitation room
(upper-story
classroom)

Fig. 2 Measurement Results for Floor
Impact Sound Levels
Heavyweight impact source

Table 1 Outline of Measurement Results

Measurement room
Sound
Width ×source room
Depth
2F ordinary classroom(intermediate section
S primaryof building)
8.4 m ×school
8.0 m
2F
ordinaryclassroom(steel structure)(corner sectionof building)
Building

Floor
specification

Lightweight impact source
Measurement result*
Heavyweight Lightweight
impactimpactFloor slab
LL-50
LH-50
150 mm(best class)(best class)Flooring(dry-type
LL-50
LH-50
double-layer(best class)(best class)floor)
Floor slab
3F ordinary classroom
LL-60
LH-50
180 mm
(RC partition wall)(best class) (second class)R primary
Flooring
8.0m×
school(finishing by
8.0 m(RC structure) 3F ordinary classroom
LL-60
LH-55
means of(dry-type partition wall)
direct putting on) (first class) (second class)*Class designation in parenthesis conforms to the guidelines of the Architectural Institute of Japan(best class: highly excellent; first class: excellent; second class: standard).
It is considered that the difference of measurement results between steel structures and RC
structures in lightweight impact is notably affected by the difference of floor specifications.

Analysis of Heavyweight
Floor Impact Sounds

In order to assess the effect of the difference of structural type (steel and RC
structures) on the floor impact soundinsulation performance, the heavyweight floor impact sound was ana7 Steel Construction Today & Tomorrow December 2021

lyzed targeting the following analytical models.
Structures Subject to Analysis
Figs. 3 and 4, and Table 2 show an outline of the steel-structure model.
Fig. 5 and Table 3 show an outline of
the RC-structure model.

90
80

Floor impact sound level (dB)

Sound receiving room
(lower-story
classroom)

Heavyweight
impact source
Steel structure
RC structure
L-75
L-70
L-65

70
60
50
40
30

L-55
L-50

L-60

L-45
L-40
L-35
L-30

20
0

63 125 250 500 1000 2000 4000
Center frequency of octave band (Hz)Analytical Cases
Table 4 shows the analytical cases. For
the analytical case of S3 (steel-structure with composite floor slab) shownin Table 4, the section of the composite
slab (deck plate depth of 50 mm + concrete of 125 mm) was structured to havea weight per unit area nearly similar toAnalytical Conditions
The in-plane/out-of-plane coupled-type
finite element method* was adopted as
an approach to analyze the vibration response. Analysis was made by setting theexcitation force and the damping performance for every octave band of 31.5~500
Hz bands. For the radiation sound analytical approach, the wave function method* was adopted. (Refer to Figs. 7 and 8)

Analytical Results
Figs. 9 and 10 show the plane distribution of vibration acceleration level obtained from the vibration response analysis.
When comparing the analytical cases of steel-structure models, the L value (classification of sound insulation) of*Reference: “Study on floor slab vibrations andUniversity of Tokyo)

Fig. 5 Framing Plan at 2nd and 3rd
Floors of RC-structure Model

Fig. 3 Framing Elevation of
Steel-structure Model

Table 3 Dimensions of Beams andColumns of RC-structure Model

Fig. 4 Framing Plan at 2nd and 3rd
Floors of Steel-structure Model

Beam

Girder G1
Girder G2
Beam B1

ColumnSectionSectional area

400×700-

400×700

Beam

SectionSectional area
123.6 cm2

Girder GY1 H-500×250×9×16
Beam B1
Beam B2
ColumnC1

123.6 cm2

H-450×200×9×14

95.43 cm2

SectionSectional area

H-200×100×5.5×8□-350×19-“High Deck KHD75” (plate thickness: 1.0 mm)
ColumnAdjusting plate
Beam
Deck plate support
Splice plate
FB-6×22

Deck plate
support
FB-6×22Beam

26.67 cm2
Deck plateOn-site cutting

239.2 cm2

Table 4 Analytical Cases
Structural
type

Classroom
Story
dimension(column-to- heightcolumn span)

S-1
S-2

Steel
structure

S-3
RC-1

RC
RC-2 structure

8.1 m ×8.1 m

4m

Floor slab

Steel
form

Balcony

RC slab
No useThickness:
150 mm
RC slabUseThickness:
Thickness:
No
150 mm
1.0 mminstaComposite slabUsellationDeck plate depth:
50 mm + Concrete Thickness:
1.2
mm
thickness: 125 mm
RC slab
No useThickness:
150 mmColumnExcitation point/
Sound receiving point

Beam

Sectional area

Fig. 6 Specifications of Steel Structurewith Deck Plate

Girder GX1 H-500×250×9×16

S-1-RC slab thickness: 150 mm; No use of steel form-

700×700
C1
Foundation 1500×1500×1500
footing

Table 2 Dimensions of Beams andColumns of Steel-structure Model

Fig. 7 Plane Condition for
Steel-structure Analytical Model-

400×500
SectionModels S-2-1 and S-2-2 with steel forms
was decreased by 1~3 from that of Model S-1 with an RC slab thickness of 150
mm, which showed an improved soundinsulation performance due to the adoption of steel forms. While the unit-areamass of Model S-3 using a composite
slab was similar to that of Model S-1, theL value of S-3 was decreased by 1 fromthat of S-1.
When comparing the steel-structure
model to the RC-structure model having an identical RC slab thickness of
150 mm, the L value of the steel-structure model (S-1) was 55 and the L value of the RC-structure model (RC-1,
RC-2) was 54~56, which showed a nearly identical trend in sound insulation performance for both the steel-structure andRC-structure models.
When examining all analytical cases, the L value of the steel-structure
model was assessed as 52~55 andPartitionwall

Dry type

Dry type
Seismicresistant wall

Indoorsoundabsorption
conditionSoundreverberationtime: 1.0 s(assuming
low-sound
zone)

Sound
receivingroom

Fig. 8 Analytical Model for Steel-frame
Beam and SlabS-1-RC slab thickness: 150 mm; No use of steel form
Analysis-target surface(slab upper-end surface)Shellelement
Y
X
Section I

Concrete
layer

Section II
SteelBar element(upper flange)
beam
Bar element (web)Bar element(lower flange)
Section I: X-Y plane stress condition
Section II: Y-direction shaft stress condition

Fig. 9 Vibration Response Distribution of S1
63 Hz
band

Vibration accelerationlevel (dB)sound radiation” by N. Hashimoto (thesis of The

Fig. 10 Vibration Response Distribution of RC-2
63 Hz
band

Vibration accelerationlevel (dB)that of the RC slab with a thickness of
150 mm.

December 2021 Steel Construction Today & Tomorrow 8

conditions, no notable difference of thesound insulation-performance between
steel structures and RC structures wasobserved.
(Refer to Table 5 and Fig. 11)

Table 5 Analytical Results for Heavyweight Floor Impact Sound Level

Fig. 11 Analytical Results for Heavyweight
Floor Impact Sound Level
100

Floor impact sound level (dB)the L value of the RC-structure model was assessed as 54~56. It was confirmed from these assessment results
that, while the sound insulation performance changed due to the difference of floor slab type and restriction(unit: dB)

Center frequency inLoctave band (Hz)Slab specificationvalue
31.5 63 125 250 500
S-1
79.4 77.9 62.2 51.3 44.6 55 RC slab 150 mm
S-2-1 78.9 77.2 63.6 50.2 44.0 54 RC slab 150 mm; use of steel form (no consideration to rib)
S-2-2 77.3 74.6 60.9 51.2 43.7 52 RC slab 150 mm; use of steel form (consideration to rib)
S-3
78.1 76.6 62.8 51.2 44.5 54 Composite slab; concrete thickness: 125 mm
RC-1 80.5 78.5 64.4 50.6 43.7 56 RC slat 150 mm
RC-2 76.7 77.1 66.1 50.4 43.7 54 RC slat 150 mm
Corrected for excitation point number and time weighting characteristics for sound level
Model

In order to assess the effect of the difference in structural types (steel structure
and RC structure) on the floor vibrationrelated habitability, the walking vibration was analyzed and examined.
Models Subject to Analysis
The same models as those used in the previous chapter “Heavyweight Floor Impact Sound” were subjected to analysis.

P2(1.2, 0.15s) P3(1.2, 0.45s)

1 P1(0.5, 0.012s)
0.5(0.67, 0.3s)
00

0.1 0.2 0.3 0.4 0.5 0.6
Time (seconds)

Excitation force/
WeightExcitation force/WeightFig. 12 Analytical Model for
Per-step Walking
Excitation Force
1.5

the previous chapter was also adopted.
As a condition for walking excitation,a case of walking by one person (specified weight: 60 kg) was assumed. As regards the waveform to input the walking
excitation force, it was settled that the
waveform per 1 step having 2 peaks atheel collision (Peak P1) and heel landing (Peak P2) was set to repeat a 0.5-second cycle at the walking pace. (Fig. 12).
Fig. 13 shows the walking excitation
force input waveform used in the analysis.
Fig. 14 shows the plane condition of thesteel-structure model used for the analysis.

Before overlaying of waveforms

1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0

0.5

1

1.5

2

2.5

Time (seconds)
After overlaying of waveforms

0.5

1

1.5

2

2.5

Time (seconds)

3

3.5

3

0
0.1
1

1.5

2
2.5
Time (seconds)

-900
-600
Excitation-300
force-input value
0
300
600
3.5
4 900
Analytical result

-0.1

0.5

3.5

3

Acceleration (m/s2)

RC-2-RC slab thickness: 150 mm; Use of seismic-resistant wall

-0.1
0
0.1
0.2 0

0.5

1

1.5

2
2.5
Time (seconds)

9 Steel Construction Today & Tomorrow December 2021

3

-900
-600
Excitation-300
force-input value
0
300
600
3.5
4 900
Analytical result

Excitation force (N)Fig. 16 Analytical Results for Time-history Response Acceleration
Waveform due to Walking Excitation
-0.2

50

31.5

63

125

250

500

Analytical Results
In order to assess the effect of the difference
in structural types (steel structure and RC
structure) on the floor vibration-related habitability, the floor vibration was analyzed targeting identical building plane plans and using various analytical models in which thedifference of the structural type was reflected.
The vibration under the excitation condition assuming one-person walking was analyzed and assessed based on the Guidelines
for the Evaluation of Habitability to Building Vibration prepared by the Architectural
Institute of Japan. As a result, the floor vibration response was assessed at V-10 or lower
for both the steel-structure and RC-structure
models. (Refer to Figs. 15, 16 and 17)

4

S-1-RC slab thickness: 150 mm; No use of steel form
ColumnExcitation point/
Assessment point
Classroom
Beam

Excitation force (N)Acceleration (m/s2)

S-1-RC slab thickness: 150 mm; No use of steel form

0.2 0

Lr-60
Lr-55
Lr-50
Lr-45

60

Fig. 14 Plane Condition of
Steel-structure Analytical Model

Fig. 15 Analytical Results for Time-history Response Acceleration
Waveform due to Walking Excitation
-0.2

70

40

Fig. 13 Walking Excitation Force Input Waveform

Excitation force/
WeightAnalytical Conditions
For the approach to analyze thevibration response, the in-plane/
out-of-plane coupled-type finite element method shown in

80

Center frequency in octave band (Hz)4

Fig. 17 Assessment Results for
Walking Vibrations (AIJ’s
Guidelines for the Evaluation of
Habitability to Building Vibration)
100

Response acceleration (cm/s2)

Analysis of Walking
Vibrations

S-1
S-2-1
S-2-2
S-3
RC-1
RC-2

90

S-1
S-2-1
S-2-2
S-3
RC-1
RC-2

10
V-90
V-70
V-50
V-30
V-10

1

0.1

0.01

0

10
Frequency (Hz)100

Calculation of Annual
Thermal Loads

Fig. 18 Building Model Used for Thermal Load Analysis

Analytical Approaches and Models
The thermal load was analyzed at an interval of 1 minute and by the use of thermal load analysis software TRNSYS. In
the analysis, the indoor heat generation,
ventilation and air-conditioning schedule was settled in conformity to the “Calculation and Judgement Methods in Accordance with Energy-saving Standards
2013”, and the Expanded AMeDAS
Weather Data (2000 edition) was used as
the meteorological data.
Analytical Parameters
Table 6 shows the parameters used in theanalysis of thermal loads.
Analytical Results for Annual
Thermal Load
It was confirmed from analysis that no
notable difference of thermal load between the steel-structure and RC-structure models was found thereby demonstrating almost no effect of a differenceof structural type on the air-condition
load.
Figs. 19 and 20 show the analyticalresults for annual thermal loads.

4,000

In order to assess the effect of the difference in structural types (steel structure and RC structure) on the thermal environment and air-conditioning load, thethermal load was calculated using the analytical model shown in Fig. 18.

12,0004,000 4,000

Ceiling: Sound-absorption
gypsum board 95

Classroom

1,500

50
45
40
35
30
25

Steel structure:
Exterior thermal insulation

3.86

3.86

3.86

Corridor

8,100
12,600

19.66

19.67

Story
heightCeilingheightClassroom
dimensionCorridor
width

Eave,
verandaTokyo
Sapporo

3

4.0 m

3.0 m

8.1 × 8.1 m

3m

1.5 m

Structural
type

Fire
protection

Partition wall
(between classrooms)

RCstructure

RC (examination only of RC structure)
RC thickness: 150 mm
RC thickness: 150 mm
Hard urethane foam 25 mm
Gypsum board 12.5 mm (gypsum lining) (Use or no use)
Basswood plywood 5.5 mm with cloth

Structural
type
Steel
structureRC
structure-

Outdoor-side
window glass
Single-layer glass
Double-layer glass
Double-layer glass(Low-E type)(aluminum sash)

Floor slab

Earthen floor concrete

RC 150 mm
Flooring: Direct
putting up

RC 150 mm
Polystyrene foam 25 mm
Polystyrene film 0.15 mm

Structural
Partition (between
Ceiling
typeclassroomand corridor)
Steelstructure Sound-absorption
Full-surface
gypsum board
glass fitting
RC
9.5
mm
structure

Cooling load(latent heat), GJ

3.85

3.86

19.24

19.27

50
45
40
35
30
25
15
5

5.74
4.71
4.20
4.93
DoubleSingleDoubleDoublelayer
layer
layer
layer
glass
glass
glass
glass
(Low-E type)(Low-E type)Specifications for window glass• While the heating load of the steel structure is lower than that of the RC
structure, the cooling load of the steel structure is higher than that of the
RC structure, and in terms of both heating and cooling loads on an annual
basis, no notable difference between two structures was found.
• The difference between heating and cooling loads is considered to be
attributable to the effect of the heat capacity of the RC structure.

Rooftop floor
Concrete trowel
Polystyrene foam 25 mm
Composite high-polymer roofing sheet 2.0 mm
RC 150 mm

Fig. 20 Effect of Thermal Insulation Specifications on
Thermal Load in Steel Structures (Sapporo)

5

4.40
Doublelayer
glass

Extrusion-formed cement
board 60 mm
Hard urethane foam 25 mm(Use or no use)
*Urethane foam in Sapporo
Examination also of 100 mm

Dry type
Steel stud C-73x45x12x0.8@303 mm
Reinforced gypsum board
15 mm + 15 mm (both sides)
Basswood plywood 5.5 mm with cloth

105.12Singlelayer
glass

Exterior wall

No use(impossible
Steelstructure
to payconsideration)

RC structure:
Exterior thermal insulation

18.95

8,100

No. ofstoriesHeating load(sensible heat), GJ
No exterior thermal
insulation
0.64
6.55

Cooling load(sensible heat), GJ

0.64

0.64

No exterior thermal
insulation
Rooftop thermal
insulation 100 mm
0.64
0.64
0.64

6.75

6.79

6.61

20
19.42

8,100
24,300Construction
site

10
0

8,100

3,000

Structural
type
Steel
structureRC
structure

20
15

CorridorTable 6 Outline of Specifications of Thermal Load Analytical Models

Cooling load(sensible heat), GJ

3.86

Aluminum sash
1,800 × 6,000

Window glass

CorridorClassroom
Full-surface
glass fitting
Classroom
Flooring:
Direct putting up

Fig. 19 Comparison of Annual Thermal Load between Steel
Structure and RC Structure (Tokyo)
Heating load(sensible heat), GJ

Exterior wall
(extrusion-formed
cement board or RC)

24.79 23.50

23.14

6.84

6.88

Cooling load(latent heat), GJ

Provision of exteriorwall thermal insulation
100 mmRooftop thermal
insulation 100 mm
0.64
7.57

24.28 22.87 22.47 19.96

0.64

0.64

8.21

8.45

17.38

16.44

0

Single- Double- Double- Single- Double- Double- Single- Double- Doublelayer
layer
layer
layer
layer
layer
layer
layer
layer
glass glass glass glass glass glass glass glass glass(Low-E type)(Low-E type)(Low-E type)Specifications for window glass• The heating load is predominant in cold districts.
• The effect of the difference of opening specifications on the thermalload is high due to reinforced rooftop thermal insulation(from 25 mm to 50 mm).
• The effect of the reinforced thermal insulation (from 25 mm to 50 mm)
is higher than that of the difference of opening specifications.
December 2021 Steel Construction Today & Tomorrow 10

Feature Article: Towards Promotion of Steel-structure Construction of Public Buildings (5)Outstanding Examples in Public Building
Construction Employing Steel Structures
Complex Facility-Sukagawa Community Center “tette”

Complex Facility Incorporating Library and Lifelong
Study Functions• Reconstruction project for the comprehensive welfare centerdamaged by the Great East Japan Earthquake
Complexfacility in which the function as a public hall is inte•
grated with a library and the multiple uses for lifelong study,
child care support and a museum are incorporated♦ Project owner: Sukagawa City, Fukushima Prefecture♦ Location: Nakamachi, Sukagawa, Fukushima Prefecture.
♦ No. of stories: 5 stories aboveground, 1 basement♦ Building area: 7,723 m2♦ Total floor area: 13,698 m2♦ Structural type: Steel structure (partly SRC structure)♦ Design: Ishimoto Architectural & Engineering Firm andUnemori Architects♦ Construction: Joint venture of Sumitomo Mitsui Construction and Sanpaku Kougyou♦ Completion: July 2018
Reasons for the Adoption of Steel Structures• At the stage of design, a new form of facility was targeted thatserves as a new activity site for citizens and as a symbol ofreconstruction. The steel structure was suitable for realizing
a column-free open space where citizens can gather together
and exchange with each other.
• The concept of mega-structure was adopted in order to realize the design that makes many terraces by stacking while setting back the floor.
-Creation of a space in which columns are not installed on
the 1st floor path; Support of the floor using suspension columns and columns installed on the intermediate floor; Formation of a large space structure with a long span of 23.4 m
in maximum length and employing cantilever beams witha maximum length of 7.65 m
In response to these requirements, a steel structure was adopted
as a rational structural system that could secure sufficient rigidity and strength required to support the upper and lower floors.
Megastructure
Flow offorce

Structural Diagram

Suspended floor

School-Shiota Junior High School
Y-shaped Steel-frame Unit to Harmonize with
Surrounding Areas and to Provide Flood Measure• Adoption of a gambrel roof that harmonizes with the landscape peculiar to an old post town
• Raised-floor structure (installation of steel-frame undergroundbeam on the pile top retained at a high position)♦ Project owner: Ureshino City, Saga Prefecture♦ Location: Shiotacho, Ureshino City, Saga Prefecture♦ No. of stories: 2 stories aboveground♦ Building area: 7,660 m2♦ Total floor area: 8,436 m2♦ Structural type: Steel structure♦ Design: Suemitsu Hirokazu+Suemitsu Yoko/SUEP+Sasaki
Nobuaki/INTERMEDIA♦ Construction: Toa Corporation♦ Completion: August 2014
11 Steel Construction Today & Tomorrow December 2021

Reasons for the Adoption of Steel Structures• Lightweight construction (the site is located in a sandbank
with weak ground, and it was required to adopt a raised-floor
structure as a flood countermeasure.)• Creation of open space• Sense of security imparted by the steel structure• Cost reduction

School-Kamaishi-Higashi Junior High School, Unosumai Primary School, Unosumai Child Hall
Reconstruction Symbol Built on High Landin a Disaster-stricken Area
• Reconstruction plan for a primary school, junior high school,
child hall and kindergarten damaged by the Great East Japan
Earthquake• Restriction of earth drilling volume of the mountain area thatserves as a building site to a minimum level and developmentof the land for a building site while retaining the mountain ridgeby working out an integrated civil engineering/building construction plan so as to suppress the construction cost and term
♦ Project owner: Kamaishi City, Iwate Prefecture♦ Location: Unosumaimachi, Kamaishi City, Iwate Prefecture♦ No. of stories: 4 stories aboveground♦ Building area: 6,309 m2 (total of primary school, junior highschool, child hall)♦ Total floor area: 11,142 m2 (total of primary school, juniorhigh school, child hall)♦ Structural type: Steel structure♦ Design: Kojima Kazuhiko+Akamatsu Kazuko/CAt♦ Construction: Joint venture of Obayashi, Kumagai Gumi,
Toyo Construction and Motomochi Group♦ Completion: March 2017
Reasons for the Adoption of Steel Structures• Selection of a steel structure by taking into account the construction cost and term, and ground conditions• In the adoption of the steel structure in the “birthplace ofthe modern steel industry, KAMAISHI,” the building design
was made by raising awareness of the positive expression ofsteel-frame members, which has improved the image of steel
frames and led to cost reduction.

Photo: Masao Nishikawa
Photography Studio

School-Bantani Primary School
Harmony with the Natural Environment, Flexibly
Expanding School Environment• Adoption of timber as an interior member• Ordinary classroom that allows flexible applications using
movable partitions♦ Project owner: Koka City, Shiga Prefecture♦ Location: Minakuchicho, Koka City, Shiga Prefecture♦ No. of stories: 3 stories aboveground♦ Building area: 3,344 m2 (school building)♦ Total floor area: 6,251 m2 (school building)♦ Structural type: Steel structure♦ Design: Katabuchi Architects♦ Construction: Joint venture of Toda and Nishimura Construction♦ Completion: March 2003
Reasons for the Adoption of Steel Structures• Lightweight construction of the building (suitable for theconstruction at the developed ground)• Reduction of surplus soil excavation due to the reduced pilefoundation work (environmental considerations)• Construction term reduction (by about 2 months from RC
construction)• Availability of large-span space and ease of change in indoor
layout• Flexible response to future enlargement and reconstruction• Recyclability of steel members in the event of demolition

December 2021 Steel Construction Today & Tomorrow 12

Government Office-Yamaga City Government Office Building and Yamaga Citizens' Exchange Center♦ Project owner: Yamaga City, Kumamoto Prefecture♦ Location: Yamaga, Yamaga City, Kumamoto Prefecture♦ Design: Kume Sekkei♦ Construction: Obayashi Corporation♦ Completion: September 2014 (main building)Government office building♦ No. of stories: 5 stories aboveground, 1 basement♦ Building area: 2,376 m2♦ Total floor area: 9,341 m2♦ Structural type: Steel structure (partly SRC structure); Baseisolation structure
Citizens' exchange center♦ No. of stories: 2 stories aboveground, 1 basement♦ Building area: 2,154 m2♦ Total floor area: 2,894 m2♦ Structural type: SRC structure (partly steel structure); Seismic-resistant structure
Reasons for the Adoption of Steel Structures• Reduced construction term, and decreased number in the useof both base-isolation devices and foundation piles due tolong-span construction• Decreased number in the use of base-isolation devices and reduced size of piles by means of lightweight construction• Adoption of a steel-RC composite structure for the basement
and concrete-filled steel tube columns in order to secure thestiffness required for a base-isolation building

Office space
ConferenceroomLarge hall

Waiting lobby

Waiting hallConsultation
room
Consultation
room

Government office
Office space

Deckterrace

Entrancehall
Waiting lobby
Citizens' exchange
centerJapanesestyleroom
Main entrance≒7ⅿ
Entrance (government office)
Kitchenhall
Conference
room

≒16ⅿ

Efficient and Functional Government Office Buildingthat is Human- and Eco-friendly• The rebuilding of the superannuated government office building for the new Yamaga City inaugurated by the merger of 1city and 4 towns in 2005; Due consideration paid to ease-ofunderstanding and use by intensively arranging the help desk
to low-rise floors; Rebuilding plan for a town building thatallows for citizens to easily gather together through the provision of a spacious public hall, meeting place and library attached to the government office building• For use as a disaster-prevention base, adoption of a base-isolation structure for the government office building, diversification of heat sources and installation of a power generator toallow continuous operation for about 72 hours, and a watertank and sewage storage tank to allow water supply for 7 days
• Design that takes into account improved maintenance andcomfortability such as energy saving measures by the useof solar power generation, rainwater, optical ducts and other natural resources and reduced solar light burdens with the
optimum use of eaves

Recep- Main entrance
tion (citizens' exchange center)

Photo: SS Co., Ltd.

Government Office-New Saijo City Government Office Building
Eco-friendly Building Constructed by the Optimized
Use of Features Unique to the Locale• Use of locally-produced timber as interior members and exterior wall members
Securementof natural ventilation by the use of ascending air•
current and prevailing wind inside the stair tower♦ Project owner: Saijo City, Ehime Prefecture♦ Location: Akeyashiki, Saijo City, Ehime Prefecture♦ No. of stories: 7 stories aboveground♦ Building area: 1,483 m2♦ Total floor area: 9,448 m2♦ Structural type: Steel structure♦ Design: Yasui Architects & Engineers♦ Construction: Joint venture of Nishimatsu Construction,
Shiraishi Construction Industry and Yumiyama Kensetsu♦ Completion: January 2014

Photo: KOKUSAIKIKAKU

13 Steel Construction Today & Tomorrow December 2021

Reasons for the Adoption of
Steel Structures• Realization of column-free business space• Decreased number in the installation of isolation devices bymeans of lightweight building
construction• Reduction of construction termHospital-Ibaraki Western Medical Center
New Hospital to Take Responsibility for Acute-phase
Medical Care in the Western Area of Ibaraki Prefecture• Reorganization project for integrating 3 hospitals- the public Chikusei Citizen Hospital and Kensei General Hospital,
and the private Sanno Hospital• Based on the experience in which former hospitals sufferedfrom the Great East Japan Earthquake, an ECI system* wasadopted so as to respond to pressing tasks for realizing hospitals that serve as a disaster-prevention base and have baseisolation functions*ECI (early contractor involvement) system: The general contractor participates in the project from the stage of design andextends technical cooperation in design thereby offering expectations for reduced construction cost and term.

♦ Building area: 8,688 m2♦ Total floor area: 19,394 m2♦ Structural type: Steel structure (base-isolated hospital building):
Steel structure (seismic-resistant information plaza building)♦ Design: YAMASHITA・NEMOTOHIDE SEKKEI JV♦ Construction: Maeda Corporation♦ Completion: August 2018
Reasons for the Adoption of Steel Structures• Adoption of long-span framing to enhance the freedom inworking out the inside plan for the hospital building• Decreased number in the installation of base-isolation devices due to long-span framing and assessment of the steel
structure as a rational structure in terms of cost

♦ Project owner: Chikusei City, Ibaraki Prefecture♦ Construction site: Otsuka, Chikusei City, Ibaraki Prefecture♦ No. of stories: 6 stories aboveground (hospital building); 1
story aboveground (information plaza building)Hospitalbuilding

Information
plaza building≒12ⅿ

Dialysis
Guard
Mortuary
Overtime Medicine Nutrition Dissection
Emergency
Medicaldiagnostic medical care
image
Blood sampling Chemical
Urine sampling treatment
RehaCentral
MedicalPhysiologicalbilitation
treatment
examination
inspection

Endoscope

Medicalmatters
Medical tie-up

Outpatient

Restaurant

Hall

Possibleto enlargeChildcareN≒12ⅿ

Hospital-Chutoen General Medical Center
LCB Hospital Constructed by the Integration of
Kakegawa and Fukuroi City Hospitals• Design of a hospital building considering the continuity of
medical function (life continuity building or LCB) becauseof the location in the epicenter of forecast Tokai Earthquake♦ Project owner: Kakegawa City-Fukuroi City enterprise consortium, Shizuoka Prefecture♦ Construction site: Shobugaike, Kakegawa City, Shizuoka
Prefecture♦ No. of stories: 8 stories aboveground♦ Building area: 11,804 m2♦ Total floor area: 44,529 m 2 (500 sickbeds, possible toincrease to 825 sickbeds)♦ Structural type: Steel structure (base-isolation structure)♦ Design: Kume Sekkei♦ Construction: Joint venture of Obayashi, Tozka and Marumei♦ Completion: March 2013
Installation of reserve
warehouse for disaster prevention
Diversion of parking lot to the takeoff/landing
space for supporting helicopter (in the event of disaster)

Reasons for the Adoption of Steel Structures• High freedom that can meet diverse architectural requirements-Less restrictions imposed on the angle on which abeam attaches to a column; Securement of column-free open
space
• High flexibility that can meet future change of functions andenlargement-Decreased number in the installation of columns by means of long span construction; Shortening of
beam depth and securement of a ceiling space required toprovide piping routes; High freedom in the arrangement of
the holes that penetrate the beam for piping• Reduction of construction term and environmental impactReduction of construction term due to labor-saving work atsite by factory fabrication of building frame; Reduction ofnoise and vibration in the surrounding environment throughlabor saving and rationalization of on-site work

Multi-sickbed room to meetthe need for increase of sickbed
in the event of disaster

Maintenance balcony for compatible
use for preventing glass from falling

Sash not collapsedby distortion

Private electric
generator

Installation ofheliport for carrying
patient (regular use)

Securement of triage spacein the event of disasterBas-isolation
construction ofenergy center

Oil tank

Photo: SS Co., Ltd.

Securement of water storagetank capacity to meet the need forwater supply in the event of disaster

Securement of general service waterin the event of disaster by means ofrainwater filtration and sterilization

Use of spring pit as the waste water
reservoir tank in the event of disaster

Lighting and ventilating to hospitalmall used to serve as treatment
space in the event of disaster

Adoption of base-isolation structure
Important coefficient 1.5 + Baseisolation structureContinuous receipt of transmitted
electricity using two circuits(dual incoming lines)

December 2021 Steel Construction Today & Tomorrow 14

Serial Article: Latest Design of Steel Buildings in Japan (6)Shibuya Station on the Tokyo
Metro Ginza Line-Column-free Subway Station Building Constructedby the Use of 45 Continuously-arranged M-shaped Steel ArchesNaito Architect & Associates
KAP
A large-scale urban redevelopment projectis being promoted at Shibuya, in downtown Tokyo. In connection with this redevelopment project, Shibuya Station on theTokyo Metro Ginza Line, located aboveground, was relocated eastward by about
130 m, and a new subway station building
covered with aluminum panels and glass
was constructed spanning Meijidori Avenue. M-shaped steel-frame arches wereadopted for the construction of the station building roof. A total of 45 M-shaped
arches were continuously aligned at an interval of 2.5 m, which brings about a column-free spacious platform with a total
extension of 110 m. (See Photo 1)
With many restrictions that had been
imposed on the building plan, how was theM-shaped arch realized? Those engaged
in the structural design of the Shibuya Station tell about the relocation project successfully completed capitalizing on theapplication of the M-shaped arches andnewly-devised construction technologies
peculiar to railway operations.
Relocation of Shibuya Station on
the Ginza LineWe think it was probably around 2009that we heard about the relocation project of Shibuya Station on the Tokyo Metro Ginza Line. The urban redevelopment
project at Shibuya had started due to theongoing superannuation of many buildings located around Shibuya Station andthe resultant need to reconstruct related
infrastructure facilities. Among these reconstruction projects was the rebuilding
plan around the Shibuya Station East Exit Square, where two relocation projects
were examined-an overpass (pedestrian deck at the East Gate of Shibuya Station, completed in 2012) that connects the
Shibuya Hikarie (complex facility building) and the East Exit of JR (Japanese
Railway) Shibuya Station and Shibuya
15 Steel Construction Today & Tomorrow December 2021

Photo 1 Spacious platform at Shibuya Station on the Tokyo Metro Ginza Line, which was realized
capitalizing on M-shaped steel arch framing

Station on the Tokyo Metro Ginza Line.
Shibuya Station on the Tokyo Metro Ginza Line is a terminal station. Although the Ginza Line is a subway line,
the platform of Shibuya Station is located aboveground because the site around
Shibuya Station is composed of a valleyshaped topography.
In the current urban redevelopment
project, it was decided that the platformof Shibuya Station on the Tokyo Metro Ginza Line be relocated eastward by
about 130 m partially spanning Meijidori Avenue, and that the relocated Shibuya
Station be reconstructed as a key facility
that connects JR Shibuya Station, Shibuya
Scramble Square and Shibuya Hikarie.

Further, in the building plan for the
peripheral area, it was decided that, aswith the overpass mentioned above,
steel girders be erected spanning Meijidori Avenue by 55 m, on which the subway runs, and that a pedestrian deckcalled Skyway be constructed further on
the railway line to connect Dogenzaka(westside area of Shibuya Station) andMiyamasuzaka (eastside area).
(Refer to Photo 2 and Fig. 1)
Examination of Configuration of
the Station Building
The new station building of Shibuya Station on the Tokyo Metro Ginza Line is anover-track station constructed spanningMeijdori Avenue and the East Exit Square,
and its total length measures about 110 m.
The platform in the former station was two
separate platforms servicing two tracks,
and its width was a narrow 6 m. In contrast, the platform on the new station is an
island platform serving two tracks, and its
width has been broadened to up to 12 m.
The periphery of the East Exit Squareis crowded with many buildings, and thus
not much of the sky can be seen. In order
to visually suppress the voluminous impression of the station building, the sectional form was designed with a configuration in which the corner section was
shaved off, rather than a square configuration. On the condition of placing the pedestrian deck on the building, further examinations were made of the building
structure. For the upper structure of thestation building, because the subway runs,
it was impossible to erect columns inside
the building. To that end, arch framing
was adopted for the construction of theupper structure of the station as it strad-

tion to the detailed track configuration,
the track at one side shows curving whenlooking from the Miyamasuzaka side,then the track runs straight in the midway, and finally it slightly expands in therailway siding area. In this way, the trackheight shows changes in terms of not only plane but also section. We felt as if wewere surrounded by diverse kinds of restrictions occurring both inside and outside of the station building. Because theheight and width of the track in the projectsite changed in three-dimensions, complex work was needed to be implemented
in the current relocation project. (Fig. 4)
The restrictions were imposed in thecourse of project promotion. It was required to proceed with the construction of
the station building without not only the
traffic close on Meijidori Avenue but also
the suspension of subway traffic. It wasalso necessary for the project to be promoted by repeating changeovers of tracks
and changing the level of the track.

dles the platform. (Refer to Figs. 2 and 3)
Among other restrictions imposed on
the relocation project was “structural clearances” such as the dimensional clearance
imposed on the location of the structuresin the space above the track. Another restriction was to proceed with the project
while regularly operating the subway line,
and thus it was required to provide certain room in the height of the frames tobe applied to the upper section of the station building. Further, it was planned to install a pedestrian deck (Skyway) on the station building. For the pedestrian deck, theinstallation level at both the Miyamasuzaka side and the JR Shibuya Station was already designated, and thus the gradient of
the pedestrian deck was also designated.
Needless to say, the gradient of the subway track was also designated. In short, theupper and lower heights at the respective
project sites had already been designated.
In terms of the plane of the stationbuilding, the track configuration was designated. While nobody pays much atten-

Fig. 1 Location of Facilities around Shibuya Station
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East Exit Square

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reserve tankLine

Photo: SS Kikaku Inc.

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Shibuya
Scramble SquaresOverpasShibuya
HikarieN

Fig. 4 Wide-section Diagram around Shibuya Station on
the Tokyo Metro Ginza Line
ShibuyaMark City

Dogenzaka

ShibuyaShibuya
Scramble
Hikarie
SquareSkywayShibuya Stationpedestrian on Tokyo Metrodeck
Ginza Line
Miyamasuzaka
JR concourse
Fukutoshin Line/
Hanzomon Line/Den-en Toshi Line Tokyu Line
December 2021 Steel Construction Today & Tomorrow 16

Curved Beams Composed ofM-shaped Steel Frames
Regarding the building framing, we examined the adoption of semi-circular arch framing at the initial stage of design. However, if
this type of framing were adopted, the contact section with the pedestrian deck would
become narrow and the framing would beunstable in order to securely bear the deck’s
large load. Then we proposed a rational arch
design that can easily bear the deck load:
Specifically, the structural height is provided
to the position where the deck is placed. Thatis, the center section of the arch framing isshaped convex downward, and the M-shaped
arch framing is structured in which the convex arch framing and upper deck structure
are integrated. (Refer to Figs. 5 and 6)
When this M-shaped arch design was
proposed, we thought this design was justright. The organic configuration producedby continuously arranging M-shaped framings is so interesting, and the letter M of the
M-shaped framing associates with the corporate mark M of the Tokyo Metro. To that
end, we thought this proposition would be
accepted by Tokyo Metro Co., Ltd. without
dissent. As expected, Tokyo Metro raised no

objection to the M-shaped framing design.
The M-shaped arch is a steel-frame
member with a height of 6.7~8.5 m and awidth of 20.5~25.2 m. Even after designation of the arch configuration to an M-shape,
examinations were implemented of the arch
erection interval and other details employing study mockups. Finally, it was decided
that a total of 45 M-shaped steel arch members would be erected at an interval of 2.5 m
to structure the entire roof framing.
The steel product adopted for the Mshaped arch was SN490B (rolled steels forbuilding structures). A feature of this Mshaped arch is the box-shaped curved beam.
The sectional dimension is 300 mm in width
for all arch members, but the height varies.
While the depth is high for the section where
the bending moment is dynamically high, thedepth is reduced for the lower end of the Mshaped arch because it serves as the pin. The
center section of the arch cannot be formed
only by the use of an M-shaped beam, andtherefore the truss was assembled by the
combined use of beams at the side of thefloor slab that is placed on the arch and the
downward convex section at the center section of the M-shaped arch. Accordingly, theFig. 5 South-North Section of the
Platform at Shibuya Station on
the Tokyo Metro Ginza Line
(Meijidori Av. Side)

Fig. 7 Detailed Section of Shibuya Stationon the Tokyo Metro Ginza Line

Skyway pedestrian deck

North
side

South
side

South side

M-shaped steel frame• Heavy-duty
corrosion-protection coating
Aluminum panel• Engagement-type
aluminum extruded member• Rib fabrication of surface
Glass panel• High-transparency
laminated glass 8+8• Steel frame: HDZ+
Phosphetic-acidtreatment

Skyway pedestrian deck
South
side

Platform

Eaves trough• Sheet water-proofing• Snow-melting device
Exterior• Aluminum cut panel (t=3)• Baking finish

Skywaypedestrian deckOn-siteweldingHigh
Ceiling
ceiling Louver• Aluminum • AluminumDL
porousextrudedShopsound-absorbing
memberwelding• Secondary plateelectrolytic
pigmentation

Platform
door

Cast steel column base

North
side

17 Steel Construction Today & Tomorrow December 2021

Adoption of Sliding Method in the
Erection of Steel Framings
In the current relocation project, because thestation building was to be constructed while
securing both Meijidori Avenue traffic and

Top light• FL laminated glass 12+12• Steel frame: HDZ+Phosphetic-acid treatment
Aluminum water-proof louver

Platform

Fig. 6 South-North Section of the
Platform at Shibuya Station on
the Tokyo Metro Ginza Line
(Station Square Side)

section of M-shaped arch became smaller.
In other words, while making full useof the curved configuration of the Mshaped arch and adding sectional devices, an arch configuration with less uselessstructural sections was realized. Although
we simply say “less useless structural section,” it would be easy for the fabricatingside to manufacture structural memberswith identical sections, but we asked thefabricating side to do their best in order torealize “less useless structural sections.”
In the initial stage of design, the topic wasbrought up as to whether the arch framingwith a configuration shown in the bending
moment drawing could be manufactured.
It would be possible to manufacture sucha framing with the use of thick structuralmembers. However, while being theoretical,
we adopted the above-mentioned M-shaped
arch by taking into account the dynamic aspect required for the roof framing. (Fig. 7)

Equipment column• Hot-extruded steel• HDZ+Phospheticacid treatment
Floor• Porcelain tile

regular subway operations, the site for installing cranes was restricted. To cope withsuch a situation, the sliding erection method
was adopted in which the temporary bent
was installed as it straddles the track, theM-shaped arch framing was assembled bymeans of on-site welding on the bent, andthen the assembled framing was moved tothe specified erection position. This sliding
method was truly an excellent technology.
Its detailed process is as follows:
At first, eight spans of arches to be erected at the Shibuya Hikarie side of the track
were assembled on the bent, which were
slid to the Hikarie side. Then three spansof arches were assembled on the bent andpushed to the JR Shibuya Station side, andthis was then repeated to cover the remaining 70 m-long platform section. The largest
arch weighed 820 tons, which was movedby 15.5 m. Lastly, arches on the bent wereassembled to complete the erection of the
M-shaped arches on the platform. A totalof 45 M-shaped arches were erected overabout one year. (Refer to Photo 3 and Fig. 8)
Tomoe Corporation in charge of the erec-tion work has handled many special building
construction projects, and thus the company accurately prepared work plans to steadily proceed such a difficult project. We surely felt the high skill offered by the Japanese
steel-frame fabricators. In addition, Tokyu
Construction Co., Ltd. in charge of the entire
project management extended joint supportin tackling this difficult project. (Photo 4)

secure the moving line at the stage of resuming operations, the project ownermade a request to install a passage where
people could pass between frames towhich unbond braces are arranged.
Regarding the section in which unbond
braces were removed, as a result of various
examinations, the framing around the opening was reinforced to maintain seismic resistance. It was helpful that the frame was originally designed as one featuring structural
redundancy and margins, and as a result
we could clear the request without any reduction of structural strength and by meansof reinforcing beams and increasing theplate thickness of frames while balancing
the structural strength of the entire framing
structure. We could successfully meet theowner’s request because of the applicationof steel structures, but if other structures had
been adopted, it would have been difficult.
On the Ginza Line, the changeoverof the track at Shibuya Station was carried out by restricting subway operation
to Omotesando Station, one stop before
Shibuya Station, during six days from De-

Erection of Unbond Braces at FourLongitudinal-direction Sections
In order to secure seismic resistance, thearch structure was securely anchored underground for the transverse-direction
section of the framing. But for the longitudinal-direction section of the building
framing, it was considered to be better tobasically adopt simple construction, andthus small-section beams were adopted.
In compensation for this, “unbond braces”(buckling-restraint braces) were arranged
in four sections of the building framing tohandle seismic forces. (Refer to Fig. 9)
After finishing the execution design
and the start of construction, in order toFig. 8 Processes of Sliding Method
Omotesando Avenue side

North bent
Protective bent
JR Shibuya
Stationside

8 spans

3 spans

South bent

The M-shaped steel-framearch is assembled on theprotective bent installed
as it straddles the track.

Eight spans of arches are slid
to the Omotesando Avenue side.
Before sliding, the exterior panel
and glass panel are attached to
the M-shaped arch.

M-shaped arch assembled
After sliding, M-shapedon the bent is slid to thearch is fixed to the pedestal
JR Shibuya Station side
by means of jacking down
basically by three spans, and and then welding.
this process is then repeated.

Lastly, the M-shaped archon the bent is assembled.
An entire span of arches wasassembled in 10 months whileregularly operating the train.

Fig. 9 Details of M-shaped Arch and Brace Section①Plate thickness adjustment gradient 1/6
or lower②AIIP (arch internal inflection point)③AEIP (arch external inflection point)▽FL

Photo 3 M-shaped arch divided into three members is carried into the construction site,which is on-site weld-joined by welding
workers.

BT-100×100×16×9
L-100×100×10
BT-150×100×16×9
G2

Slab plate: PL9①
Seal welding of joint
Slab longitudinal rib: ③P3
PL9×180 @500
③P2
Stiffener
HTB 4-M16
HTB 4-M20
PL9③P1
Stiffener
PL9
②P7

③P4
G7 steel▽STL
frame
core P23

HTB 2-M22

2×PL9-176×96

PL25-200×600
HTB 4-M16

G3

L-100×100×10

PL9

②P8

PL12

Lateralstiffener
PL16②P9

Stiffener PL9

Stiffener PL9②P10
Stiffener
PL16

PL16
HTB 2-M20
PL12
HTB 2-M20

G7 steel frame core P24
PL12
HTB 2-M20③P5

Stiffener
PL16
②P11

PL12
HTB 2-M20

G7 steel frame
core P25

Stiffener PL9V2
PL12
HTB 2-M20
HTB 4-M20
PL9
PL16
PL9
PL16

PL16

PL16
PL16

PL16
PL9
PL9

Stiffener
PL16

G7 steel frame core P26

PL16
HTB 2-M16

Stiffener PL9
H19

Brace section
V2

GPL19

GPL19

G9

Photo 4 All those involved in M-shape frame
fabrication at the Oyama Plant ofTomoe Corporation gathered together
to confirm the mockup and make final
adjustments.

G7

Cast steel pin
column baseArch-main beamjoining base point②P12

G7 steel frame
core P27

PL12
HTB 2-M20

Bearing
pin center
P28

Unbond brace section

December 2021 Steel Construction Today & Tomorrow 18

cember 28, 2019, to January 2 of the following year. During these six days, a totalof 5,000 workers participated in the trackchangeover. We happened to be present at
the work site and were overwhelmed by
the large and complex scale of the work.
While we observed the track changeover work from the command room
where monitor TVs were set up, on-site
workers attached pin cameras on their
helmets, and when the command room
instructed “No. 2 worker! Please reflect
this side,” the instructed image of thatside was projected on the monitor TV.
After finishing the round-the-clock workover six days, the new Shibuya Stationon the Tokyo Metro Ginza Line resumed
its regular service with the departure ofits first train on January 3, 2020.
Exact Assessment of Excellent
Technologies
In the design of special buildings requiring
difficult structural work such as the stationbuilding introduced above, the first task is
to search for an appropriate company fromamong many steel-frame fabricators. While
there were many fabricators with special
and advanced technologies, regrettably
there were cases in which some of these fabricators had not kept going. In cases when
the cost that offsets the special technology is
not accepted, we think that the level of technological capability of Japanese fabricators
will follow to decline. We consider it necessary to establish the concept that “advanced
technology naturally requires proper cost.”
In the current relocation project, manytechnical experts extended their cooperation.
This has helped us to understand the important
theme of how many such excellent experts
can be secured in the future, too. How many
experts will continue to exist around us in the
future-especially those having high technical expertise vis-à-vis such fields as welding
technology and the accurate sliding control ofsteel frames? This seems deeply involved in
the future development of steel-structure culture. Without such experts in the future, projects such as this one will not be feasible. The
reason why we, architects, can challenge thetask of difficult projects is attributable to thefact that these technical experts are ready toextend their full support.

Outline of Shibuya Station on the Tokyo Metro Ginza Line
Location
Project owner
Main application
Area

Shibuya, Shibuya-ku, Tokyo
Tokyo Metro Co., Ltd.
Railway facility
Site area:
9,899.42 m2
Building area: 2,662.80 m2
Total floor area: 5,212.52 m2
Main building Steel structure
Structure
2 stories aboveground, 2-story basement
No. of story
Maximum height 20,000 mm
Architecture Naito Architect & Associates
DesignMetro Development Co., Ltd.
Tokyu Architects & Engineers Inc.
Structure: KAP
Equipment: P.T. Morimura & Associates, Ltd.
Joint venture of Tokyu Construction Co., Ltd., Shimizu Corporation
Construction
and Kajima Corporation
October 2015~June 2016
Design term
Construction term August 2018~December 2019
Photo courtesy of

Photo 5 Full view of the platform at Shibuya Station on the Tokyo Metro Ginza Line.
Advanced steel construction technologies were fully applied in the station
relocation project.

STEEL CONSTRUCTION TODAY & TOMORROW
Published jointly by

The Japan Iron and Steel Federation
3-2-10, Nihonbashi Kayabacho, Chuo-ku, Tokyo 103-0025, Japan
Phone: 81-3-3669-4815 Fax: 81-3-3667-0245
URL https://www.jisf.or.jp/en/index.html
Japanese Society of Steel Construction
3F Aminosan Kaikan Building, 3-15-8 Nihonbashi, Chuo-ku, Tokyo 103-0027, Japan
Phone: 81-3-3516-2151 Fax: 81-3-3516-2152
URL http://www.jssc.or.jp/english/index.html

19

Makoto Yoshida of Nikkei Architecture and Naito Architect & Associates© 2021 The Japan Iron and Steel Federation/Japanese Society of Steel Construction
Edited byCommittee on Overseas Market Promotion, The Japan Iron and Steel Federation
Chairman (Editor): Keiji AndoP u b l i s h e d t h r e e t i m e s p e r y e a r, S T E E L C O N S T R U C T I O N TO D AY &TOMORROW is circulated to interested persons, companies and publicorganizations to promote a better understanding of steel products and theirapplication in the construction industry. Any part of this publication may be
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