No. 69 December 2023

STEEL CONSTRUCTIONTODAY & TOMORROW

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

Feature Article

Marking Rule for Steel
Properties
1 Quality Assurance for Steel Products and Marking of Properties
in Japan

3 JSS I 02-2017 Marking

Rule for Steel Properties

6 JSS I 02-2017 Marking

Rule for Steel
Properties―Commentary

9 Practical Examples ofMarking Rule for Steel
Properties

Special Topic
11 Achieving Carbon Neutrality in the Japanese Steel Industry

Serial Article: Latest Design of Steel Buildings in Japan (8)Yamato Konan Building
15 A Double Spiral Structure
Enables a Museum andPeripheral Vehicle
PassagePublished Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel Construction

Feature Article: Marking Rule for Steel Properties (1)Quality Assurance for Steel Products
and Marking of Properties in Japanby Tsuyoshi Tanaka
Chairman of Subcommittee on Revision ofMarking Rule for Steel Properties, Vice Chairmanof Committee on Technologies and Standards,
Japanese Society of Steel Construction (Professor,
Graduate School of Engineering, Kobe University)
Quality Assurance for Steel
Products
In steel-structure construction, when thegrade of the steel products applied in theconstruction differs from that specified
in the design documents, the completed
structure will present serious problems interms of structural safety, and there mayarise situations in which rebuilding is required depending on the situation.
In general, after the shipment of steel
products from steelmakers, these products are delivered to steel-frame fabrication plants via steel product distribution
companies and intermediate processing
companies. In order to verify the quality of the steel products to be applied to
the final products manufactured by steelframe fabrication plants, it is necessary
to prepare unified rules for verifying
steel product quality at the stage of distribution.
To cope with such a need, the quality verification method called the “endorsement system” has been firmly established in Japan. The quality of steel
products can be confirmed by collatingwith standardized product certificates(mill sheets). However, when steel prod-(1) Label-attached wide flange beam
Photo 1 Stage of shipment from steelmakers
1 Steel Construction Today & Tomorrow December 2023

Tsuyoshi Tanaka: After finishing the mastercourse
at the Kobe University, he entered the Asanuma
Corporation in 1985. Then, he served as assistantat the Kobe University in 1992. He assumed his
current position as a professor at the Kobe University in 2010. His main research themes are thedesign of beam-to-column connections and the construction of welded connections in steel buildings.

ucts are distributed via complex routes, it
is likely that the steel products deliveredfrom the steelmaker and a mere copy ofthe standardized product certificate may
not match each other. In order to prevent
such a mismatching from occurring, the“endorsement system” is applied. Specifically in this system, the person who
confirms whether or not the delivered
product matches with the original standardized product certificate implements
quality assurance by using the original
certificate-equivalent standardized product certificate with his signature and seal,
company name/company seal and the delivery date. This system also makes it
possible to trace steel products.
Marking of Steel Product
Properties
At the same time, even when the steel
products ordered by the steel-frame fabricating plant arrive correctly, misuse islikely to occur when workers at the steelframe fabrication plant do not correctly
understand the grade of the steel products. This makes it impossible to apply
the proper fabrication method suitableto each grade of steel products appliedin respective fabrication processes. For
example, it becomes impossible for thewelder to choose the appropriate welding
wire and welding method at the welding
stage.
At the shipping stage from the steel
product maker, the grade of steel products can be understood by collating withthe label and stencil pasted on the steel
product as shown in Photo 1. However,at the stage of distribution, steel products
are subjected to cutting or other secondary processing to manufacture processed
products. Further, at the steel-frame manufacturing plant, steel products undergo
cutting and fabrication. When steel products undergo cutting and fabrication, it
becomes impossible to know the gradeof the steel products from the appearanceof the fabricated steel members. Accordingly, it becomes necessary to establish arule required to understand the grade of
the steel products delivered from steelmakers by taking a look at these fabricated members.
In Japan, with the aim of marking
steel product grades, the Japanese Society of Steel Construction established“JSS (Japanese Society of Steel Con-

(2) Stencil-attached square steel tube

struction Standard) 4-1971 Marking
Rule for Structural Steel Performancewith Color Coating” in 1971. JSS 4-1971
was cited in the "Japanese ArchitecturalStandard Specification" published by theArchitectural Institute of Japan and the“Specifications for Highway Bridges”
published by the Japan Road Association, which led to the wide establishmentof JSS 4-1971 as a method for marking
the properties of steel products in Japan.
Along with the diversification of steel
grades and their classes, this standard
was revised three times in 1985, 2004
and 2017, and the current version is “JSS
I 02-2017 Marking Rule for Steel Properties.”
Among the representative marking
methods specified in “JSS I 02-2017
Marking Rule for Steel Properties” is acolor-coated line indication system. Thisis the system in which the steel grade
marking color is linearly coated on theedge or surface of fabricated members(see Fig. 1). As for the marking colors, two colors are properly used-thestrength reference color to be coated inconformity with strength classifications
and the supplementary color to be coatedto distinguish the grade of the specified
product from those of other products.
Photo 2 shows its practical application.
Incidentally, in the practical marking operation, it is important to mark the steel
grade for each piece of a steel productprior to their cutting and fabrication.
When marking is performed after cutting, the steel grade may be incorrectly
indicated due to a careless mistake.
Unified Rules for Marking Steel
Properties
In the economic bubble period startingfrom the middle of the 1980s, inappropriate design/construction as well as themisuse/mixed use of steel grades at thesteel member manufacturing stage cameto light, thereby causing social concerns.
In order for the required steel products tobe correctly applied at all times in steelstructure construction, it is essential that
not only steel structure-related industries

and companies correctly understand theknowledge and meaning of quality assurance and the marking of steel properties
but also that they use these unified rules
for the marking of steel properties.
•••
In the following pages, the full version of
JSS I 02-2017 “Marking Rule for Steel
Properties” is introduced with the content shown below:
JSS I 02-2017 Marking Rule for Steel
Properties
1 Scope2 Marking Method
2.1 Steel Grade Indication System
2.2 Color-coated Line Indication System
2.3 Colored Character Indication System
Commentary
1 Scope2 Marking Method
2.1 Steel Grade Indication System
2.2 Color-coated Line Indication System
2.3 Colored Character Indication System
Appendix

Fig. 1 Color-coated Line Indication System
Construction work symbol

Structural member symbol

Indication of steel grade on the surface

Indication of steel grade on the edge

(1) Steel plate
Photo 2 Practical example of color-coated line indication system(2) Through diaphragm and square steel tube

December 2023 Steel Construction Today & Tomorrow 2

Feature Article: Marking Rule for Steel Properties (2)Japanese Society of Steel Construction
Standard JSS I 02-2017 Marking Rule for
Steel Properties

Japanese Society of Steel Construction
1. Scope
In the field of buildings and bridges,
steel products shall be applied in which
the properties are marked based on JIS
standards or their corresponding standards. This standard specifies the method to be used for marking the steel grade(symbol of the grade of steel products)
of fabricated members to which shearing
and other fabrication methods are provided during the distribution process ofthese steel products. However, this shallnot apply if otherwise agreed between
the parties involved in delivery.
The steel grades subject to “Marking
Rule for Steel Properties” are as shownin Table 1.
2. Marking Method
The steel grade is usually indicated onsteel products such as plates/sheets,
shapes and tubes at the stage of shipment from the steel product maker using a label, spraying (stencil) and/or other means. In the case when the indicatedsteel grade is lost at the stage of distribution of fabricated products to which
shearing and other fabrication methods
are applied, and the remarking of steel
grade is required, marking is provided
by the use of any of the steel grade indication system, color-coated line indication system and colored character indication system as shown below.
2.1 Steel Grade Indication System
In this system, characters that indicate
the steel grade (symbol of the grade of
the steel product) are indicated on thesurface or edge of fabricated members
by means of hand-writing, stamping,
printing, pasting or other corresponding methods. The color of characters is
not specified, but a color shall be appliedthat allows the steel grade to be clearly
distinguished.

2.2 Color-coated Line Indication
System
In this system, the steel grade marking
color is linearly coated on the edge or surface of fabricated members. The marking
color is composed of the strength reference color that conforms to the strengthclassification of the steel products and the
supplementary color that is used to distinguish the kind of steel product as required. The strength reference color shallbe the color shown by the strength rating of the steel products as shown in Table 2. In addition, the white, blue, silver
and black colors shown in the footnotesof Table 2 are used as supplementary colors. Incidentally, the colors are based on
the color names specified in JIS Z 8102
(names of non-luminous object colors),
and the color specification conforms to
JIS Z 8721 (color specification-specification according to three attributes).

Table 1 Steel Grades Subject to JSS I 02-2017 Marking Rule for Steel Properties
JIS G 3101

Name of standards
Rolled steels for general structure

JIS G 3106

Rolled steels for welded structure

JIS G 3136

Rolled steels for building structure

JIS G 3114

Hot-rolled atmospheric corrosion resisting
steels for welded structure

JIS G 3140

Higher yield strength steel plates for bridges

MDCR 0016 TMCP steels for building structure
MDCR 0004 520 N/mm2 rolled steels for building structure
N/mm2 high-performance steels for
MDCR 0017 550
building structure
N/mm2 high-performance steels for
MDCR 0013 590
building structure
JIS G 3444

Carbon steel tubes for general structure

JIS G 3475

Carbon steel tubes for building structure

Steel grades
SS400
SM400A, B, C
SM490A, B, C
SM490YA, YB
SM520B, C
SM570
SN400A, B, C
SN490B, C
SMA400AW, BW, CW
SMA400AP, BP, CP
SMA490AW, BW, CW
SMA490AP, BP, CP
SMA570W, P
SBHS400
SBHS400W
SBHS500
SBHS500W
TMCP325B, C
TMCP355B, C
SM520B-SNB, SNC
TMCP385B, C
SA440B, C
STK400
STK490STKN400W, B
STKN490B
STKR400
STKR490

Carbon steel square and rectangular tubes forgeneral structureroll-formed square steel tubes for building BCR295
MDCR 0002 Coldstructurepress-formed square steel tubes for
BCP235MDCR 0003 Coldbuilding structure
BCP325
Coldpress-formed
high-performancesquareMDCR 0012 steel tubes for building structure
BCP325T
MDCR (Market Development Committee Regulation): The Japan Iron and SteelFederation standards

JIS G 3466

Notes to JSS I 02-2017 Marking Rule for Steel Properties
1) Translated and published by Japanese Society of Steel Construction
2) Translation without guarantee. In the event of any doubt arising, the original standard in Japanese shall take precedence.
3) Send any comment and question about this standard to Japanese Society of Steel Construction (contact details: see back cover).
3 Steel Construction Today & Tomorrow December 2023

Table 2 Strength Reference Colors and Color Specifications
Classification of strength rating
Strength reference color (typical color symbol)
2
400 N/mm grade
Green (5G5.5/6), white (N9.5)
490 N/mm2 grade
Yellow (2.5Y8/12), orange (2.5YR6/13), blue (2.5PB5/6)
520 N/mm2 grade
Pink (2.5R6.5/8)
550, 570, 590 N/mm2 grade
Purple (7.5P5/12), red (5R4/13)
Supplementary colors:
White (N9.5): Used to mark rolled steels for welded structureBlue (2.5PB5/6): Used to mark TMCP steel
Silver (N6.5): Used to mark atmospheric corrosion resisting steel
Black (N1.5): Used to mark fire-resistant steel

In the case of marking by means ofcolor-coated line indication with the target placed on steel plates and sheets,
marking is indicated linearly on the edgeor surface of fabricated members according to the combination of marking colors
shown in Table 3. In principle, the indication of the color-coated lines shall bedone on the edge, but may be done on
the surface.

Table 3 Steel Grade Marking Methods by Means of Color-coated Line Indication and Colored Character Indication(Steel Plates and Sheets)
Steel product
Classification

Steel grade

490 N/mm2
grade

520 N/mm2
grade

550 N/mm2
grade
570 N/mm2
grade
590 N/mm2
grade

Building Bridge Marking color
White

SS400

400 N/mm2
grade

Color-coated line indication

Application

A
B
SM400
C
AW, AP
SMA400 BW, BP
CW, CP
A
B
SN400
C
A
B
SM490
C
AW, AP
SMA490 BW, BP
CW, CP
B
SN490
CB
TMCP325CA
SM490YB

Yellow-White

SBHS400

Blue
Blue-Silver

W
B
C
SM520
B−SNB
B−SNC
B
TMCP355C
B
TMCP385
C
SM570
W, P
SMA570
SBHS500
SA440

W
B
C

Green-While

Green-Silver

Green

Yellow-Silver
Yellow
Yellow-Blue
OrangePink-White
Pink
Pink-Blue
Purple-Blue
Red
Red-Silver
PurplePurple-Silver
Red

Colored character indication

Indication
1 white line
1 green line+1 white line
2 green lines+1 white line
3 green lines+1 white line
1 green line+1 silver line
2 green lines+1 silver line
3 green lines+1 silver line
1 green line
2 green lines
3 green lines
1 yellow line+1 white line
2 yellow lines+1 white line
3 yellow lines+1 white line
1 yellow line+1 silver line
2 yellow lines+1 silver line
3 yellow lines+1 silver line
2 yellow lines
3 yellow lines
2 yellow lines+1 blue line
3 yellow lines+1 blue line
1 orange line
2 orange lines
1 blue line
1 blue line+1 silver line
2 pink lines+1 white line
3 pink lines+1 white line
2 pink lines
3 pink lines
2 pink lines+1 blue line
3 pink lines+1 blue line
2 purple lines+1 blue line
3 purple lines+1 blue line
1 red line
1 red line+1 silver line
1 purple line
1 purple line+1 silver line
2 red lines
3 red lines

Marking color

Indication*1

White

−
MA
MB
MC
AW, AP
BW, BP
CW, CP
NA
NB
NC
MA
MB
MC
AW, AP
BW, BP
CW, CP
NB
NC
TB
TC
A
B
H※2
HW※2
MB
MC
NB
NC
TB
TC
TB
TC
Q※3
W, P
H※2
HW※2
B
C

Green

Green

Green

Yellow

Yellow
Yellow
Yellow
Orange
Blue

Pink

Pink
PurpleRed
Red
PurpleRed*1: The character TMC is added in the case of marking TMCP (thermo-mechanical control process) steel for bridge construction.
*2: For higher yield strength steel plates for bridges (SBHS), because TMCP steel is a mainstream grade, H to indicate the steel grade
is indicated in the case of marking TMCP steel (HW in the case of marking atmospheric corrosion resisting steel), and Q is added in
the case of marking Q (quenched/tempered) steel.
*3: For SM570, the character Q is indicated in the case of marking Q steel, and the character TMC is indicated in the case of marking TMCP steel.
December 2023 Steel Construction Today & Tomorrow 4

In the case of marking by means ofcolor-coated line indication with the target placed on shapes and tubes, the marking of shapes is provided in conformity
with the combination of marking colors
shown in the color-coated line indicationin Table 3, and that of tubes according to
the color-coated line indication in Table
4. For both shapes and tubes, marking
shall be indicated linearly on the edgeor surface of fabricated members as withplates and sheets.

2.3 Colored Character Indication
System
In this system, marking is indicated using the strength reference colors in Table
2 and by means of indicating abbreviatedsymbols (characters) to indicate the steel
grade on the surface or edge of fabricatedmembers. Clearly legible characters shallbe applied, and in order to distinguishfrom other characters, the characters may
be enclosed using 〇 or □. The practicalindication method is shown in the coloredcharacter indication in Table 3.

Table 4 Steel Grade Marking Methods by Means of Colored Character Indication(Steel Tubes)
Steel productApplication

Classification

Building

Steel grade

Bridge

STK400Circular steel
tubes

400 N/mm
grade

W

STKN400

B−

STKN490

B

BCR295
BCP235

Square steel
tubes(SN400B)(SN400C)

BCP325(SN490C)

BCP325T

5 Steel Construction Today & Tomorrow December 2023

1 green line
2 green lines

Yellow

2 yellow lines

White

1 white line

−

Green

1 green line

−

Green

−

Blue
(SN490B)

1 white line

1 blue line

STKR490490 N/mm2
grade

Green

IndicationBlue

STK490
STKR400

400 N/mm2
gradeMarking color
White

2

490 N/mm2
grade

Color-coated line indication−

Yellow−

Yellow-Blue

2 green lines
3 green lines
1 blue line
2 yellow lines
3 yellow lines
2 yellow lines+
1 blue lineFeature Article: Marking Rule for Steel Properties (3)JSS I 02-2017 Marking Rule for Steel
Properties-Commentary

Japanese Society of Steel Construction
1. Scope
Since the revision of JSS I 02-2004“Marking Rule for Steel Properties” in
2004, JIS G 3140 higher yield strength
steel plates for bridges (SBHS) was established. In the field of building construction, new steel products have beendeveloped, which have been establishedunder MDCR (Market Development
Committee Regulation) by the Japan
Iron and Steel Federation. In the current

revision of JSS I 02-2017 “Marking Rulefor Steel Properties,” the following steel
grades were newly added.
• Higher yield strength steel plates forbridges SBHS400 SBHS400W SBHS500
SBHS500W (JIS G3140)• Steels for building structure SM520BSNB,SNC TMCP325B,C TMCP355B,C
TMCP385B,C
Cold
press-formed high performance•square steel tubes for building structure BCP325T
Incidentally, SS490 (rolled steels forgeneral structure), which was conventionally included in the scope, was excluded from the steel grades subject to
JSS I 02-2017 because of its rare application in the field of building construction and no specifications as anapplicable steel grade in the “Speci-

Commentary-Table 1 Steel Grades Subject to JSS I 02-2017 Marking Rule for Steel Properties(Comparison before and after Revision)
Name of standard

Steel grade
FormerNew

JIS G 3101
Rolled steels for general structure
JIS G 3106
Rolled steels for welded structure

SS400
SS490
SM400A, B, C
SM490A, B, C
SM490YA, YB
SM520B, C
SM570
SMA400AW, BW, CW
SMA400AP, BP, CP
SMA490AW, BW, CW
SMA490AP, BP, CP
SMA570W, P

SS400

JIS G 3114
Hot-rolled atmospheric corrosion resisting
steels for welded structure
JIS G 3140
Higher yield strength steel plates for bridges
JIS G 3136
Rolled steels for building structure
MDCR 0016-2016
TMCP steels for building structure
MDCR 0004-2015
520 N/mm2 rolled steels for building structure
MDCR 0017-2016
550 N/mm2 high-performance steels forbuilding structure
MDCR 0013-0004
590 N/mm2 high-performance steels forbuilding structure
JIS G 3444
Carbon steel tubes for general structure
JIS G 3466
Carbon steel square and rectangular tubes
for general structure
JIS G 3475
Carbon steel tubes for building structure
MDCR 0002-2017
Cold roll-formed square steel tubes forbuilding structure
MDCR 0003-2017
Cold press-formed square steel tubes forbuilding structure
MDCR 0012-2017
Cold press-formed high-performance square
steel tubes for building structure

SN400A, B, C
SN490B, C

Subject or not subject to
JSS I 02-2017
SS490: Not subject to JSS I

SM400A, B, C
SM490A, B, C
SM490YA, YB
SM520B, C
SM570
SMA400AW, BW, CW
SMA400AP, BP, CP
SMA490AW, BW, CW
SMA490AP, BP, CP
SMA570W, P
SBHS400
SBHS400W
SBHS500
SBHS500W
SN400A, B, C
SN490B, C
TMCP325B, C
TMCP355B, C
SM520B-SNB, SNC
TMCP385B, C

Addition
SBHS700, 700W: Not subject to JSS I

Addition
Addition
Addition

SA440B, C

SA440B, C

STK400
STK490
STKR400
STKR490

STK400
STK490
STKR400
STKR490

STKN400W, B
STKN490B
BCR295

STKN400W, B
STKN490B
BCR295

BCP235
BCP325

BCP235
BCP325

Revision of MDCR in 2017: Increaseof size range

BCP325T

Addition

Revision of MDCR in 2017: Increaseof size range

December 2023 Steel Construction Today & Tomorrow 6

fications for Highway Bridges” in thefield of bridge construction. As for SBHS700 and SBHS700W (higher yieldstrength steel plates for bridges), sinceboth grades show lower records of application, it was decided that the arrangement of marking in their application be commissioned to the parties
concerned. As for square steel tubes,
while new grades such as UBCR365,
BCP385, SHC400 and SHC490 havebeen developed and put into practicaluse, common specifications have notyet been established, and thus it was decided that the arrangement of marking
in their application be commissioned tothe parties concerned.
The steel grades subject to JSS I 022017 “Marking Rule for Steel Properties”
were increased from 10 grades at its establishment in 1971 and 24 grades at thetime of its revision in 2004 to 32 gradesin the current revision in 2017. The colors used for color-coated line indication
is limited, and thus it has become difficult to settle an indication method common to buildings and bridges.
Meanwhile, the result of surveys of
related industry organizations revealed
that the most common marking method in the field of buildings is the color-coated line indication system, andthat in the field of bridges is the colored character indication system using
strength reference colors, and thus thesteel property marking method appliedin the field of buildings differs considerably from that in the field of bridges. Further it was learned from survey
results that rolled steels for building structure (SN grade), higher yieldstrength steel plates for bridges (SBHS
grade) and other steel products specialized for the required performance forbuildings and bridges have been standardized under JIS, and that along withthe diversification of steel products,
the steel grades commonly used in thefield of buildings and bridges are limited to rolled steels for welded structure(SM grade). Then, the standardizationof independent marking by application was discussed, but it was predicted that there would be some confusion
concerning incorrect use and markingof steel products at shearing companies who receive orders for cut sheets
and plates from not only the fabricator
involved in both buildings and bridges but also the building and bridge construction companies. Based on a comprehensive judgement of this situation
7 Steel Construction Today & Tomorrow December 2023

and from the viewpoint of preventing
confusion, independent standardization
by application was not the aim, and it
was decided to not aim to mark by application but to maintain the conventional marking system common to bothfields.
2. Marking Methods
Three versions of “Marking Rulefor Steel Properties” have thus far
been published-the Japanese Society of Steel Construction Standard JSS
4-1971 Marking Rule for Structural
Steel Performances with Color Coating
established in 1971, the revised original draft published in JSSC’s bulletin
in 1985 and the former version revisedin 2004. As to the name of the marking method used in these three versions, various terms such as character
indication, color-coated indication, color-coated line indication and coloredcharacter indication were used, and thename itself was also changed in these
versions. While the changes were implemented in each revision by adapting to the current situation, it was hardto understand the details of revisions,the main text of the JSS and the content
of the commentary. To remedy this, it
was decided in the 2017 revision thatthe marking method be classified into
three systems-the steel grade indication system, color-coated line indication system and colored character indication system so as to unify the term ofmarking method.
Meanwhile, for steel products suchas plates and sheets, shapes (wideflange beam, angle, channel, flat) andtubes (circular and square), the steel
grade is usually indicated at the stage ofshipment from steel product makers bymeans of labelling and spraying (stenciling). Particularly for rolled steels forbuilding structure (SN grade), there isa case in which marking of steel grade
and its class is provided on the surfaceof steel products. In this process, marking is printed on the surface of steel
products at the stage of their shipmentfrom the steel product makers, and because marking remains in the fabricated members after shearing, this marking is accepted as the most reliable anddesirable marking system. Further, forsteel shapes and other products, there
are many cases in which the productlabel is pasted that indicates the steel
grade, cast or inspection number, dimensions and maker’s name. Howev-

er, because a unified indication method for marking the steel grade of theseproducts has not been applied, it was
decided that this would not be subject
to JSS I 02-2017 as with past JSS versions.
The targets subject to “Marking Rulefor Steel Properties” are fabricatedmembers processed from steel products
by means of shearing and other processing methods. In the case when thesteel grade indication provided by thesteel product maker is lost at the stageof distribution of sheared members represented by cut plates and sheets or
fabricated members subjected to otherfabrication processes, requiring the remarking of steel grade on these fabricated products, it was decided to markthese members by the use of any of thefollowing three systems-steel grade
indication system, color-coated line indication system and colored character
indication system.
2.1 Steel Grade Indication
System
A system in which the characters to indicate the steel grade (symbols of thegrade of steel products) is shown on thesurface or edge of the steel products or
fabricated members by means of handwriting, stamping, printing, pasting orother similar methods. All characters toindicate the grade are indicated, not justthe abbreviated symbol. While the color used to indicate the characters is not
specified, white is mostly applied. At
shearing companies and the plants that
manufacture various types of intermediate members, hand-writing directlyon the fabricated members is frequently applied.
Recently, with the progress of production systems, the dot system andother automated printing devices arebeing increasingly introduced for use
for printing of member symbols andcharacters, and the wider application of
automated printing devices is being desired from the viewpoint of labor-saving and preventing incorrect indication.
2.2 Color-coated Line Indication
System
A system in which the color to markthe steel grade is linearly coated on theedge or surface of steel products or fabricated members. This system has been
adopted in the Japanese Architectural Standard Specification JASS6 of theArchitectural Institute of Japan and hasbeen firmly established within the society. This is the fundamental marking
method that can be commonly adopted,
not only for plates and sheets but also
shapes and tubes.
The common practice is to indicate
the grade by means of vertical coatingof color lines along the edge. This is ahighly efficient system for the markingof cut plates and sheets, because they
can be coated at once while piled up.
The coating of vertical or horizontal
lines on the surface is also available.
With this color-coated line indication system, various kinds of steel
grades can be indicated by means of theuse of combined colors. The basic concept in color coating is the combined
use of strength reference color used toindicate the strength rating and the supplementary color used to distinguishthe different steel grades with identical strength as the need arises. Regarding the supplementary color, while silver has conventionally been used only
for marking the atmospheric corrosion
resisting steel, the frequency of application of supplementary colors has increased since the last revision in whichsteel grades were increased due to themarketing of rolled steels for building structure (SN grade) and other new
products.
In the last revision in 2004, SN
grade (rolled steels for building structure) was added, and it was specified
that “green + white lines” be used for
SN400 grade to distinguish from the“green line” for SM400 grade pertaining to the 400 N/mm2 grade, and thatthe “yellow + white lines” be used for
SN490 grade to distinguish from the“yellow line” for SM490 grade pertaining to the 490 N/mm2 grade. In the fieldof buildings, the frequency of application to SN grade is higher than that of
SM grade, and while indication using
one color is used for SM400 and 490
grades, two colors to which a supplementary white color is added to thestrength reference color is used for
SN400 and 490 grades. There were many opinions that the two-color indication would cause more issues, and as
a result, the relevant organizations requested that the color-coated line indication system for SM grade should be
replaced with that for SN grade. On
the other hand, in the field of bridges,
SN grade has not been applied, and SM
grade is the mainstream grade.
Conventionally, the basic policy

was not to change the indication system for existing steel grades. However, in the current revision, based on thepresent situation in which the SN grade
accounts for about 70% of total steel
product distribution even if distribution for bridges is included, it was decided that a revision be made to reflect
the need in the field of buildings. As
a result, the color-coated line indication system for SM grade (rolled steels
for welded structure) was changed in
the field of bridges, but here coloredcharacter indication is the mainstream
marking system and the color-coatedline indication system shows less application. To that end, it was judged that
this change would not have a significant impact.
Incidentally, regarding the “bluecolor” used for SS490 grade, this was
adopted as the marking color for SBHS400 (higher yield strength steel
plates for bridges), and in the field ofbuildings it was also adopted as the
supplementary color to indicate TMCP
steel.
2.3 Colored Character Indication
System
A system in which abbreviated symbols(characters) to indicate the steel grade
are indicated on the surface of fabricated members using a strength referencecolor. Because both member symbol indication and colored character indication happen concurrently, this is a comparatively simple method. In order tomake clear that the character indicatesthe steel grade, the character is frequently enclosed with 〇 or □. The colored character indication system shownin Table 3 is the method that indicatesthe steel grade and detailed grade classification (classes such as A, B, C) as
easily as possible. Incidentally, the reason why examples of colored character
indication is not shown in Table 4 Steel
Grade Marking Methods by Means ofColored Character Indication (SteelTubes) is that steel tubes are composedof many kinds and thus the standardization of abbreviated symbols (characters) is difficult, and that it was judged
desirable to adopt the color-coated line
indication system applied to the edge orsurface of members or the steel grade
indication system with which all characters that indicate the steel grades areindicated.
Recently, there have been cases inwhich TMCP steel has been appliedin place of SM and SMA steels in thefield of bridges. In this regard, in the“Specifications for Highway Bridges,”
the specification of thermo-mechanical processing and linear-reheatingstraightening for use for non-quenched/tempered steel differs from that for
TMCP steel, which has thus required
proper marking. Consequently, it wasalso decided to indicate TMC characters pertaining to TMCP steel underJSS I 02-2017. Two grades, quenched/tempered steel and TMCP steel, areavailable for SM570 and SMA570, andthus it was decided to indicate a Q in
the case of marking quenched/tempered
steel and TMC in the case of marking
TMCP steel. Also, two steel grades,
quenched/tempered steel and TMCP
steel, are available for SBHS grade, but
because the mainstream grade of SBHS steel is TMCP steel, it was decided
to indicate a Q in the case of marking
quenched/tempered steel and to require
no indication in the case of TMCP steel.
On the other hand, for example,
when the detailed grade classification(classes such as A, B, C) of steel products can be judged based on the application standard of the steel grade byplate thickness or the detailed classification of steel grades can be marked by
the use of other means, it has become
possible to mark the steel grade only byindicating the member and construction
work symbols on the surface of fabricated members using strength referencecolors. Because this approach can serveboth as member symbol indication andsteel grade marking, its distinctive feature is high efficiency in marking operations, and thus it can be said that
this approach is a kind of color-coatedcharacter indication system. Incidentally, when the member symbol can be indicated by the use of white characters
printed using an automated printing device, it is impossible to mark by theuse of colors, and thus it is necessary
to mark using the color-coated line indication system shown in 2.2 above orother means.

December 2023 Steel Construction Today & Tomorrow 8

JSS I 02-2017 Appendix
Practical Examples of “Marking Rule for Steel Properties”
Construction work symbol
Member symbol

Indication of steel grade on the surface(In the case of marking SN490B steel plate)

Steel Grade Indication System

SN490B steel plate (hand-written)

Indication of steel grade on the edge

TMCP325C steel plate (stamped)

Color-coated Line Indication System

SN490C steel plate (edge)

TMCP325B steel plate (surface)

SN490B wide-flange beam (edge)

BCP325 square steel tube (corner surface)

9 Steel Construction Today & Tomorrow December 2023

Colored Character Indication System

SN490CTMCP355C (enclosed with 〇)Examples of Steel Products Requiring No Marking
Conditions in which labels and stencils remain in shapes and tubes

Wide-flange beam (attached with label)

Wide-flange beam (with stencil)

Square steel tube (attached with label)

Square steel tube (with stencil)

December 2023 Steel Construction Today & Tomorrow 10

Special Topic

Achieving Carbon Neutrality in theJapanese Steel Industry

by Toshio Isohara
Chairman, Task Force for Carbon Neutral Steel
Advancement, The Japan Iron and SteelFederation

Low-carbon Steelmaking with
Hydrogen
Steel is produced in extremely large volumes compared to other materials andused as the basic material of various industries. As a result, steel emits at thestage of production as much as 14% of
CO2 (after allocating CO2 emissions
from power generation) of the total emissions in Japan. Thus, reducing its emissions is an urgent issue for the Japanese
steel industry.
Steel is generally produced by removing oxygen (reduction) from iron ore using carbon (coal or coke) in the blast furnace-basic oxygen furnace (BF-BOF)
process. In the process, CO2 is emitted
as follows.
• 2Fe2O3 + 3C → 4Fe + 3CO2

Toshio Isohara: General Manager, Technical
Administration & Planning Div., Nippon SteelCorporation. Expert in LCA, product sustainability andlow carbonization in steel production. He has various
work experience including heads of R&D planning,
R&D laboratory and intellectual property. He is also
the chair of the Planning Committee for Technological
Policy, The Japan Iron and Steel Federation.

The carbon intensity in steel production is low compared to those of othermaterials. However, as mentioned above,
the total CO2 emissions are extremely
high because of the huge amount of steel
produced. On the other hand, if hydrogenis used in steel production, only water is
produced and no CO2 is generated, as described below.
• Fe2O3 + 3H2 → 2Fe + 3H2O
Japanese blast furnace steel companies have been supported by the New Energy and Industrial Technology Development Organization (NEDO) in the R&Dof the COURSE50 (CO2 Ultimate Reduction System for Cool Earth 50) project. The project is designed to reduce theCO2 emissions of blast furnaces by 10%
with hydrogen, and by 20% with CCUS

(CO2 Capture, Utilization and Storage)
resulting in 30% reduction as a total. In
2018, the Experimental Blast Furnace
installed at the Kimitsu site of Nippon
Steel Corporation demonstrated 10% reduction of CO2 emissions by means ofhydrogen injection. A CO2 capture facility using a new type of absorbent was also installed near the Experimental Blast
Furnace, and a linkage test was conducted (Fig. 1).

Fig. 1 COURSE50 Experimental Blast Furnace (left) and CO2 Capture Facility (right)

Blast furnace
StripperOre storage bin
Hot stove

Absorber

PCI*

Reboiler*PCI：Pulverized coal injection
COURSE50
Experimental Blast Furnace

11 Steel Construction Today & Tomorrow December 2023

NEDO・JISF：COURSE50

COURSE50
CO2 capture facility

NEDO・JISF：COURSE50

Fig. 2 Conventional, COURSE50 and Super COURSE50 Blast Furnaces and Hydrogen Direct Reduction Shaft Furnace
Conventional blast furnace

COURSE50

CO2

Carbon(Coal)Super
COURSE50

CCU
CCS

CarbonCarbonHydrogenHydrogen

CCU
CCS

Hydrogen direct
reduction

Hydrogen

Molten slag Molten ironhydrogen-producing countries and the
DRI imported to Japan.
However, hydrogen will be used invarious sectors in the future, so it will be
important for society to build a hydrogen supply infrastructure to meet thesehydrogen demands. In addition, in orderto produce steel at the same cost level
as current coking coal, hydrogen prices
must be lower than the government vision level. However, since there will bea lower limit of hydrogen cost, social acceptance for the increased price of lowcarbon steel is also required (Fig. 4).

is highly expected as the ultimate lowcarbon ironmaking process and various
research has started in various countries.
The amount of hydrogen required forsteel production is enormous. If all of Japan's current steel production were to be
produced using hydrogen, approximately 20 million tons of hydrogen would be
required annually. This is equivalent to
the entire amount of hydrogen that theJapanese government has vision to supply in Japan by 2050. Since carbon-freehydrogen is expected to be imported, it
will be possible that DRI is produced inFig. 3 Reduction of Iron Ore Using Carbon (left) and Hydrogen (right)
CO

H2

Iron ore

Iron ore

CO2

Iron

Hydrogen

H2O
Water

Iron

Iron ore reduction with carbon

Iron ore reduction with hydrogen

Fig. 4 Hydrogen Cost and Price Visions of the Japanese Government (circles)
and Trend (broken curves)
Hydrogen cost & price ( USD/kg-H2 )Since hydrogen is not currently available in large quantities, COURSE50 assumes the use of hydrogen produced in
integrated steel mills during coke production. Assuming that hydrogen will be available in large quantities at low cost in the
future, the Super COURSE50 project has
also started to inject larger quantities ofhydrogen into the blast furnace. Recently,
22% reduction in CO2 emissions has been
demonstrated by injecting heated hydrogen into the Experimental Blast Furnace.
In the blast furnace, solid coke supports
the iron ore even at high temperatures andmaintains gas ventilation in the furnace.
Therefore, the coke amount cannot be zero, and reduction cannot be performed with
100% hydrogen in the blast furnace. On theother hand, 'direct reduction' in which ironore is made into pellets and reduced withnatural gas in a shaft furnace is also usedalthough the production amount is relatively small. The shaft furnace is small in size
compared to blast furnace, but it is possible
to reduce iron ore using only hydrogen byreplacing natural gas with hydrogen. Thisis called 'hydrogen direct reduction' (Fig.
2). The iron obtained by direct reduction
is called direct reduced iron (DRI), whichmust be followed by melting in an electricarc furnace etc. Furthermore, direct reduction requires high-grade iron ore, producedin less than 10% of the total iron ore, because if the raw material contains a large
amount of gangue, a large amount of electricity is required to melt it.
In addition, the reaction of iron ore withCO, main reaction in the blast furnace, isan exothermic reaction and so the reducediron is melt in the blast furnace. On the other hand, the reaction of iron ore with hydrogen is an endothermic reaction, so heating is required for the reaction (Fig. 3).
As described above, direct reduction
using hydrogen has various issues, but it

7.0
6.0

Imp

5.0

Dom

esti

4.0
3.0

c pr
odu

ed

ctio

hyd

n co

rog
e

st

nC

IF p

rice

National vision in 2030

2.0

National vision in 2050

1.0
0
2020

ort

2025

Hydrogen price equivalent to current coking coal
2030
2035
2040
2045

2050

December 2023 Steel Construction Today & Tomorrow 12

Low-carbon Steelmaking with
CO2 Capture
Conversion of CO2 into chemicals andminerals or geological storage of CO2
is another effective means of reducing CO2 emissions. The challenge of
CCUS is the economics of CO2 capture. In case of CCS, there are additional issues including transportation
cost of CO2 to storage sites often in remote areas, monitoring cost, and social
acceptance of the storage.
Biomass is considered a carbonneutral carbon-based reducing agent
because it absorbs CO2 from the atmosphere through photosynthesis when
it is generated. Charcoal, in particular, has a certain degree of strengthand can be used in small blast furnaces as a substitute for coke, and has beenused in Brazil where forest resources
are abundant. On the other hand, it canlead to deforestation and its sustainability can be an issue.
Low-carbon Steelmaking with
Scrap
Steel scrap is a useful steel resourcethat has already been reduced. Currently, one third of the world's steel is produced from steel scrap, and this figure
will continue to increase as steel stockincreases in the world. The problemof scrap is the contamination of othermetals. Steel is a highly recyclable material that can be separated from other metals by means of magnetic sorting, and most of other metals can beeasily removed as their oxides (slag)by oxygen refining. However, copper
which is widely used in wire harness
and core in motors is easily mixed withsteel scrap. Once cupper is melted withsteel, it is impossible to remove. Contaminated copper degrades the quality of steel and accumulates in steel
resources. Preventing copper contamination in scrap is a major issue fromthe perspective of not only steel resource circulation but also low-carbon
steel production.
It is sometimes pointed out that Japan produces as low as about 25% ofscrap electric arc furnace steels, which
is low carbon emissions in production
phase, compared to USA, for example,
which produces as high as 60% of electric arc furnace steel. However, in USA,a large amount of blast furnace steel isindirectly imported as final products
and used. In Japan, contrary, about 60%of blast furnace steel is exported. As aresult, the percentage of scrap used in
the steel products used in both countries is about the same. It is important tonote that looking only at the producing

phase tends to lead missing carbon leakage where carbon is not reduced but only emitted outside the country.
Low-carbon Steelmaking with
Electricity
Since carbon emissions from electric
power generation will become lower due to increase of renewable energy
sources, iron ore reduction by electrolysis might become an option. Boston
Metal is attempting to produce molten
iron by molten oxide electrolysis. ArcelorMittal is trying to produce iron byelectrowinning. Although both of thesetechnologies still have significant challenges to overcome in terms of productivity and large-scale production, they
are expected to be highly energy-efficient in terms of direct use of electricity without conversion to hydrogen.
Their progress is noteworthy for steel
industry.
Low Carbon Roadmap andChallenges
The roadmap to carbon neutrality insteelmaking presented by the Japan
Iron and Steel Federation (Fig. 5) indicates that the Japanese steel industry
parallelly develops COURSE50, SuperCOURSE50, and hydrogen direct reduction, while combining CCUS.

Fig. 5. Roadmap of the Japan Iron and Steel Federation to Carbon Neutral Steel

Fundamentals insociety

Technology development bysteel sector

2020

13 Steel Construction Today & Tomorrow December 2023

2030

2040

2050

2100

The Japanese blast furnace companies have formed a consortium for hydrogen steelmaking 'GREINS (GREen
INnovation in Steelmaking)' with supports by NEDO as the 'Green Innovation Fund project: Hydrogen utilizationin steelmaking processes.' In the project,comprehensive joint studies are being
developed including COURSE50, Super COURSE50, hydrogen direct reduction, and advanced electric furnace technologies. In addition, steel producers in
the world, including Japan, are challenging to low carbon steel, with targets ofreducing CO2 emissions by around 30%
in 2030 and vision of carbon neutrality in
2050 (Fig. 6).

Fig. 6. Roadmap to Zero Emissions by Steel Producers (Scope 1+2)
TATA Europe

0%

Nippon SteelSalzgitter

JFE

USS, HBIS

Nucor
Kobe SteelTATA India
VA Baowu

AM

HBI

S

-10%
Ind

JFE

-20%

TA

TA

Baowu

ia

Kob
e
Nippon Steel Steel
Nuco
r

AM

Eu

ro

pe

POSCO (Scope 1)
Tokyo Steel (Scope 1)
US Steel
AM global-40%

TATA Europe, TK, VA, JFE, Kobe Steel, Nippon SteelTATA India
AMSSAB
EuropeAnSteelNucor(SBTi)TATA Netherland, Kobe Steel-50%

Salzgitter-60%

Tokyo Steel

-30%

HBIS
POSCO

-70%
-80%

: CO2 emissions intensity: CO2 emissions

-90%
-100%
2010

2013

2018

SSAB
2020

2030

Salzgitter
2035

2040

2050

December 2023 Steel Construction Today & Tomorrow 14

Serial Article: The Latest Designs of Steel Buildings in Japan (8)Yamato Konan Building-A Double Spiral Structure Enables a Museum andPeripheral Vehicle PassageNikken Sekkei Ltd.
Yamato Konan Building is a 10-story
composite logistics building that accommodates a variety of functions, including a home delivery service center,a corporate museum and training facilities. The sloped vehicle path, as wellas the sloped museum, wrap aroundthe building’s periphery in a “double
spiral” design. At upper levels, theseslopes are suspended from a steelframed hat truss structure, while thelower floors are supported by cantilevers. The highly rationalized space also capitalizes on prevailing conditions
at the site.
Trucks Traverse the Building’s
Periphery
The original Yamato Konan Buildingsite featured a collection/delivery center with an attached dormitory for Yamato Transport. The company wished
to rebuild it as a futuristic facility on
the occasion of the 100th anniversaryof the founding of the Yamato Group.
Specifically, the project called for thefacility to accommodate a training center for human resource development, a
corporate museum for public relations,and a café for physically-handicapped
employees while retaining its collection and delivery functions. The relatively compact 2,480 m2 site area required a highly rationalized design tomeet all of the client’s needs.
The building’s 1st to 5th floors areused for loading and unloading, while
the 6th floor serves as the entrance forthe museum, and the 7th to 10th floors
host the office and training center. At
the lower floors, the vehicle passage
connecting the logistics center and museum wrap around the building in a
double spiral. The passages connect tothe 50 m-high top floor, as they change
function.
In such multi-storied logistics facilities, independently-structured ramp-

ways with flat floors to the side areusually provided for vehicles to traverse the upper and lower floors. However, no matter how the rampway is arranged, the passage length remains thesame, leaving unused space surrounded by the vehicle passages. To that end,
this innovative design allows for flat,
wide floors to be arranged in the building center, routing vehicles to the outer periphery.
In order to prevent damage to deliverable goods, Yamato Transport specified a more gradual vehicular passageway gradient than is typically seen.
The resulting design allows the vehicle to ascend one level per half lengthof building periphery, or two levels
for every 360-degree “round-trip.” As
this design still left one level of vacant
space between the passages, an additional passage was allocated as a museum exhibition space. (Photos 1 and 2)

Photo 2 Conceptual model: The blue spiralshows the vehicle passage where thevehicles ascend/descend. The orange
spiral depicts the corporate museum.

Photo 1 Canal side (east side) view. Arriving delivery vehicles can be seen through diagonally-slatted
sections in the glass façade.
15 Steel Construction Today & Tomorrow December 2023

Bringing Out the Slope from the
Flat SpaceAs the structural performance requirements of the sloped passage and exhibition space differed from the logistics
center, office and training facilities, anumber of mechanisms were needed tointegrate the building’s diverse functions.
A 36 m × 27 m flat space was allotted to the building center. A structural frame secures the floor, while thesloping peripheral passageways aresupported by cantilevers that protrude
from these floor structures. Because
the structural plane is essentially identical throughout the building’s levels, it
was possible to design a well-balanced
building, provided that its structural elements were properly arranged.
At first glance, it seemed logical toinstall columns along the outer periphery. However, it was feared that with
the Takahama Canal on the east sideof the site and the old seawall on theboundary, providing foundation beams
or driving piles near the seawall mightdestabilize it (the seawall). Thus,
the decision was made to support thebuilding structure and the slopes at the
periphery from the center.
Piles could have been driven at thefront (west side) of the building, thereverse side of the canal. Ultimately,
however, no outer periphery columns
or structural elements were placed
there in order to strike a total building
structure balance. Employee and vehicle entrances are also located on thisside, so this structural design conceptalso benefited these circulation plans.
The logistics center required 10ton trucks to enter from the 1st floor.
Taking streetscape and atmosphere improvement priorities into consideration, the rebuild plan allows vehicles
to line up at the rear canal side, an aesthetically better solution than the previous layout in which they lined up at
the former coastal street side. (Figs. 1,
2, 3, and Photo 3)

Fig. 1 Sectional View

Spiralterrace

Lounge StudioSpiralterrace

Spiralterrace

Seminar room

Spiralopen space

Spiralopen space

OfficeSpiralterrace

SpiralMeetingterrace Lounge room
Exhibition
room

OfficeOfficeSpiralopen space
Peripheral
vehiclepassage

Peripheral
vehiclepassageCargo disposal/parking

Exhibition
room

Cargo disposal/parking

Peripheral
vehiclepassage

Peripheral
vehiclepassageCargo disposal/parking

Exhibition
room

Café
Peripheral
vehiclepassage

Takahama
Canal

StudioCargo disposal/parking
Cargo disposal/parking

Exhibition
room

Peripheral
vehiclepassage

FormercostalstreetFig. 2 Plane View

Seminar room
StudioLounge9th floor

10th floor
Peripheral vehicle passage

Exhibition room
Exhibition
room
Peripheral
vehiclepassageCargo disposal/
parking

Exhibition
room
Peripheral
vehiclepassage

Exhibition
room

Peripheral vehicle passage
3rd floor

Exhibition
room

6th floor

Former coastal street
Peripheral vehicle passage
Peripheral
vehiclepassage
Peripheral
vehicle Cargo disposal/
passageparking

Cargo disposal/
parking

Peripheral
vehiclepassage

Peripheral vehicle passage

Peripheral
vehiclepassage
EV hall

Café

Lobby

2nd floor

1st floor
Takahama Canal

December 2023 Steel Construction Today & Tomorrow 16

Seismic-resistant brace
5400 1850

Fig. 3 Framing Plan
Slope

Y6

7200

Y5

Y4

13000

Flat floor

7200

Y3

8000

6000

6000

12000

6000

6000

1850

5400

Y2

Slope

Y1

8000

Steel Frame Cantilever andSuspension Structures
The structural performance specifications
for the building’s lower floors differ fromthe upper floor specs. Floors 1 to 5 are dedicated to cargo handling; delivery trucks
traverse the vehicle passage on the periphery. The corporate museum entrance is on
the 6th floor, where guests arrive by elevator. Guests can view the exhibitions whilemoving down the sloped exhibition spaces
between the truck paths. In this way, mobility is maximized for both people and vehicles. The lower floors were treated as acontiguous “mobile zone.” A 7.2 meterlong cantilever beam structure supports
the periphery at the east-west sides. Beamheight is 700~1200 mm.
In order to counter vibration, beams
were required to be satisfactorily rigid.
Vibration measurements were taken at theexisting building and at the newly completed building via rigorous testing; results proved that vibration levels were notproblematic. The little overlap between
the museum operating hours and the truck
operating hours helped to mitigate vibration. Finally, the cantilever beam tips ateach floor were connected using 190 mmdiameter steel pipes to counter movement
beneath and above the passages.
The 6th through 10th floor area wasconsidered a “quiet zone” due to its designated office and training center use. Nevertheless, measures were also taken here
to mitigate vibration. A steel-frame hat
truss was installed at the topmost floor,
and the upper floor peripheral section was
structured by suspending edge columns(composed of 190 mm-diameter steel
pipes) from the truss. As previously explained, the mechanisms used to support
the building’s peripheral structure differ between the mobile and quiet zones.
Oil dampers installed on the intermediate
floor also help to absorb and neutralize
vehicle-generated vibration effects.
17 Steel Construction Today & Tomorrow December 2023

Photo 3 Vehicle passage circumscribing the building’s outer periphery

Yamato Konan Building is unique inthe planar relationship between its center floor and periphery, and in terms of thesectional structural performance differences between its upper and lower floors.
Symmetrical architectural floor plans
were employed to deal with this. (Fig. 4)
Truss Frame Installation andSlope Gradations
A total of four hat trusses were installedon the top floor. These cross east to south,
connecting the building’s front and canal sides, where there were no peripheral columns rooted at the lower levels.
In turn, columns were placed along thenorth and south sides (the gable sides) of
the building for good earthquake-resistant balance. The hat trusses could only
be installed where the floor was flat inorder for them to be effective. Therefore,
Fig. 4 Sectional View
Hat truss

Suspended column

Oil damper

Stabilizing column
Formerreclaimedseawall
Takahama Canalthey were placed where the slopes at thecanal side and front side flatten for vehicles to enter and exit the cargo space.
The slope rises by one floor halfway
around the periphery. A general gradient
was applied for the slopes on the northand west sides where there are pillars.
For the corners, a gentler (flatter) gradient
was applied. Generally speaking, slopes
would be made of reinforced concrete. In
this project, however, because the lower
floors are composed of a 7.2 meter-deep
cantilever structure, lightweight durable
steel frames were adopted. This structural design accounted for improved member fabrication efficiency -- made possible by applying as much commonality as
possible for items such as joint position.
For the vehicle passages, particularly in curved sections, calculating for water gradient and the difference in gradi-ents for the right and left sides of truck
wheels was tricky.
Slope gradients differ for vehicles andpeople. The exhibition space (where visitors walk around) employs a combination of slopes and landings based on Japan’s Barrier Free Law, which promotes
easy mobility and accessibility for theaged and disabled.
The building’s center, with stacked flat
floors, is the structural core. A seismic-resistant brace was arranged at its four corners to prevent large axial forces onto the
diagonal beams. While beams are intricately arranged at these braces, they could
still be used as a building service-related
shaft space. The architectural design teamwas tasked to prepare symmetrical floor
plans; thus, the structural design team accepted that elements in its purview would
also be arranged symmetrically.
Interestingly, the corner sections
shown in the framing plan formed a radial state. The indoor ceiling was thus divided into a radial form (as opposed to amore orthodox x-y axis). Perforated ceiling panels of 474 mm width were alignedwith space between them to create a fanlike pattern. With perforated materials,
slight differences in their spacing did
not pose a concern. Panel positioning at
the corner sections did pose a challenge,
however. Panels were not aligned in aconcentric circle but placed on a shifting plane center to honor continuity. The
panels were designed to enable final adjustments at the construction site. (Photos 4, 5, 6, 7 and 8)
Upper Floor Use and Changing
Applications
The flat spaces in the center of the 7th to10th floors are home to offices and training facilities. The peripheral vehicle passage at the lower floors turns into outdoor terraces with abundant greenery at
higher floors. Meanwhile, the slope thathosts to the corporate museum on thelower floors also serves as conference
and employee refreshment areas.
During the height of the COVID-19
pandemic (when social distancing becamea priority), the peripheral space was ingeniously utilized as an office space that company employees could use freely. (Photo 9)
The Glass Screen Façade
The glass screens diagonally arranged on
the building’s periphery allow passers-by tosee vehicles as they move through the interior. For the exhibition rooms and otherindoor spaces for which functional glass isrequired, another glaze was added to the in-

Photo 4 Top-floor hat truss

Photo 5 Erection of four trusses to the north andeast directions

Photo 8 Corner section slope construction
Photo 6 Through the open evacuation door, both theexhibition room and collection/delivery
center can be seen, showcasing the
intriguing difference between levels andduality of space.

Photo 9 A communication spiral circumscribes
the office space, and includes a windowside bench.

Photo 7 Corner section wall surface construction

December 2023 Steel Construction Today & Tomorrow 18

terior, forming a “double skin” design. The
outer glass assumes the image of a worn
scarf, and is single-glazed. Functionally, it
reduces some heat load during the summer.
This single-glazing is cut diagonally to display the aesthetic value of the cut edge.
In order to reduce costs and the construction period, a 9 m-long glass “belt”
was prepared, composed of glass panels, each measuring 1.2 m in width and2.6 m in height. The belts were arranged
by staggering them vertically to make thejoints less noticeable. The glass belts appear to have continuous vertical mullions,but they are instead aluminum fittings
that cover the edges of the glass panels.
The actual load bearing elements lie inside these panels. The connected fittings
look, in the end, like mullions, however.
Earthquake resistance is achieved byvertical, independently rocking units, forwhich necessary space is provided between the glass penels. The façade is split
by its glass belts, which allows huge clearances in the event of earthquakes. No displacement is structurally accumulated in
the belts, a feature which enhances overall
seismic resistance. Open spaces between
the belts also serve to ventilate the vehicle
passage and terrace areas. (Photo 10)
A Project Where People andVehicles are Equal
This project piqued our interest with respect to the concept of diversity. We rarely come across a context in which people and vehicles coexist on roughly equal
footing. In order to change or create anew
such a “non-discriminatory” space, seamless continuity is necessary. With wheelchairs, strollers, and emerging robotics, etal, mobility is consistently related to continuity. We feel that Yamato Konan Building is in the middle of this society-wide
trend, and may deserve consideration as aforerunner of this era.
In the end, this project is not an attempt to create a new concept building,but rather the result of a thought process
in creating a space to meet client needs;
as such, it seems to represent the state oftoday’s society. (Photo 11)

Yamato Konan Building Outline
Location: Minato-ku, Tokyo
Photo Courtesy
Owner: Yamato Transport Co., Ltd.
Photos 1, 3, 6, 9 and 11: Noda Harunori,
Main applications: Garage, office, museum
gankohsha
2
Photos 2, 4, 7, 8 and 10: Nikken Sekkei Ltd.
Area Site: 2,482.66 m
2
Photo 5: Maeda Corporation
Building area: 2,242.93 m
Total floor area: 19,542.80 m2
Structure: Steel structure, steel and reinforcedconcrete composite structure
No. of stories: 10 stories aboveground
Maximum height: 59.55 m
Eave height: 58.62 m
Architectural design: Nikken Sekkei Ltd
Structural design: Nikken Sekkei Ltd
Construction: Maeda Corporation
Design period: June 2016~February 2018
Construction period: February 2018~September 2019

Photo 10 Exterior building construction, with a façade composedof small glass aggregates

Photo 11 The top-floor studio and lounge are continuously connected to the terrace.

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© 2023 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): Takashi Shibuya
P u b l i s h e d t h r e e t i m e s p e r y e a r, S T E E L C O N S T R U C T I O N TO D AY &TOMORROW is circulated to interested persons, companies and publicorganizations to promote a better understanding of steel products and theirapplication in the construction industry. Any part of this publication may be
reproduced with our permission. To download content (PDF format), please go
our website at: https://www.jisf.or.jp/en/activity/sctt/index.html. We welcome yourcomments about the publication and ask that you contact us at: sunpou@jisf.or.jp.