ISO/FDIS 20895

ISO/TC 167/WG 3
ISO/TC 167
Secretariat: SN
Date: 2025-11-0412-12
Welded joints performance for seismic steel structures
FDIS stage
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Welded joints . 2
4.1 Applicable structural performance . 2
4.2 Mechanical properties of base metal . 3
5 Mechanical testing . 3
5.1 Type of testing . 3
5.2 Test specimens . 3
5.3 Testing procedure . 23
6 Acceptance criteria . 23
6.1 Basic Demand . 23
6.2 Critical Demand . 23
7 Re-testing . 24
8 Test reports . 24
Annex A (informative) Example welded joints of steel structures . 26
Annex B (informative) Relationship between the structural performance and the acceptance
criteria for Critical Demand . 37
Bibliography . 40

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 167, Steel and aluminium structures.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
Structural safety is needed in high public occupancy facilities, tall or large-scale structures, and other
important facilities. Higher performance is needed for structures subjected to seismic actions. In the case of
steel frame structures, integrity of welded joints determines the structural safety of these structures, because
welding is often used with beam to column connections, joints of steel members, member assembly, etc. It is
especially important to ensure the strength and toughness of the welds.
This document addresses the mechanical testing methods and acceptance criteria for weld metal and heat
affected zones. These mechanical properties, coupled with appropriate designs for the seismic force resisting
system, proper connection designs and detailing, as well as appropriate weld quality and inspection criteria
are essential to ensuring the high structural safety of steel structures of seismic design.
This document specifies the target performance regarding the strength and toughness of welded joints in the
acceptance criteria, but does not mention the means for realizing the performance. Rather, the document
intends to present the performance-based standards, in recognition of diverse construction methods and the
need to promote and disseminate new technologies.
v
Welded joints performance for seismic steel structures
1 Scope
This document defines two performance levels for welded joints, namely Basic Demand and Critical Demand,
for longitudinal tensile strength of weld metals, impact toughness of weld metals and heat affected zones
(HAZ) to suit the level of seismic performance specifications required for welded steel structures.
This document supplements the provisions of the standards or codes for welding procedure qualification in
the application of new steel materials, welding consumables, or complex joints, for welds that require the
performance of Basic or Critical Demands as specified by the engineer in the contract.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 148--1, Metallic materials — Charpy pendulum impact test — Part 1: Test method
ISO 4063:2023, Welding, brazing, soldering and cutting — Nomenclature of processes and reference numbers
ISO 6892--1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
3.1 3.1
structural performance
qualitative or quantitative representation of the behaviour of a structure related to its safety and
serviceability, durability, and robustness under various actions
3.2 3.2
basic demand
required properties of welded joints based on the conventional welding parameters and specifications of
materials used
3.3 3.3
critical demand
required properties of welded joints that prevent brittle fracture and ensure sufficient level of cumulative
plastic deformation capacity expected of beams welded to beam-to-column connections
3.4 3.4
sequential testing
group or set of tests for which either a certain average or an individual test results, or both, are required, for
demonstrating that the specification requirements have been satisfied
4 Welded joints
4.1 Applicable structural performance
This document specifies the two structural performance levels, namely Basic Demand and Critical Demand,
for welded joints of steel structures listed below:
— — beam to column;
— — column to column, beam to beam;
— — welded built-up box section column, H-beam and H-column.
The Basic Demand is a performance category considered to be exhibited at a minimum based on the
specifications of materials used as base materials. This refers to the performance level that can be ensured
even if it is not specified in the design drawing as a special specification, etc., and it is set on the assumption
that the performance obtained by the general construction method in the steel frame manufacturing exceeds
this. This performance category represents the minimum requirements for mechanical properties of steel
structure welded joints for which seismic performance is required.
The Critical Demand is a performance category recommended by various advanced research efforts to ensure
higher safety. This is the performance level that is applied when it is specified in the design drawing as a special
specification, and to realize this goal, it is necessary to designate special materials for use and to manufacture
them with the higher technological system.
This document may be applied to various types of welded joints of steel structures (see Annex AAnnex A),),
but the definitive rules on the level of performance to be adopted in individual circumstances of welded joints
are not given in this clause. Table 1 shows theThe levels of required performances applicable to various
welded joints shall be in accordance with Table 1.
The range of plate thicknesses of welded joints to which this standard applies are the base metal plate
thicknesses shown in Table 2Table 2 or Table 3Table 3. Application to members exceeding this thickness
range can be determined by engineers based on structural tests.
Table 1 — Applicable structural performance
Performance
Welding process b b
Performance
Table 1 — Applicable structural performanceTypeType
a a
process
of welded joint
Basic Critical
(ISO 4063:2023)
Demand Demand
Single-bevel-groove, butt joint
Beam flange to through diaphragm (see
111,114, 135,136,138 X X
Figures A.1Figures A.1 and A.2A.2))
Beam to beam (see Figure A.3Figure A.3)) 111,114, 135,136,138 X ―
Column to column (see Figure A.4Figure A.4)) 111,114, 135,136,138 X ―
Single-bevel-groove, T-joint and corner joint
Beam flange to column (see Figures A.5Figures A.5 and
111,114, 135,136,138 X X
A.6A.6))
Column to through diaphragm (see Figure A.7Figure A.7)) 111,114, 135,136,138 X ―
Welded built-up box section column (Corner welding, see
111,114,12,135,136,138 X ―
Figure A.8Figure A.8))
Performance
Welding process b b
Performance
Table 1 — Applicable structural performanceTypeType
a a
process
of welded joint
Basic Critical
(ISO 4063:2023)
Demand Demand
Square-groove, T-joint
Inner diaphragm for welded built-up box section column
772 X X
(see Figure A.9Figure A.9))
Double-bevel-groove, T-joint
Welded built-up H-beam and H-column (T-joint, groove
111,114,12,135,136,138 X ―
welding, see Figure A.10Figure A.10))
a The most commonly applied welding processes, but not limited to those shown in this table.
b X : applicable; ― : not generally applicable.
NOTE The Critical Demand is established because brittle fractures of welded joints were conspicuously observed in
the damage caused by the Great Hanshin Earthquake in 1995 and subsequent experimental research. In the series of
research efforts, brittle fracture of beam flange welds for beam to column connections and inner diaphragm electroslag
welds for welded built-up box section columns were regarded especially problematic. In order to prevent such fractures,
it has been found that a considerably higher Charpy absorption energy than has conventionally been considered needs
[2-6[2-6] ]
to be secured in the welded joints . .
4.2 Mechanical properties of base metal
4.2.1 Toughness of base metal
The steel materials constituting welded joints of seismic steel structures, to which this document applies, shall
be structural steels for which the lower limit values of toughness have been specified regarding the Charpy
impact absorption energy. The lower limit values shall be greater than or equal to the acceptance criteria
regarding Charpy impact tests on welded joints specified in Clause 6Clause 6. The test temperature shall be
the lowest service temperature of the steel structure determined by the engineer based on national
regulations, codes, standards, etc. Steel materials for which the lower limit value of Charpy impact absorption
energy is not specified may be used if a toughness value was added optionally to the steel material
specifications.
4.2.2 Tensile strength of base metal
The range of tensile strength R of steel materials constituting welded joints is from 400 MPa to 740 MPa, for
m
which the Basic Demand or Critical Demand defined in this document is required.
5 Mechanical testing
5.1 Type of testing
Two types of mechanical testing performed shall be a weld metal longitudinal tensile test and an impact test.
5.2 Test specimens
5.2.1 Shape and dimensions of specimens
5.2.1.1 Tensile test specimens
The dimensions of test specimens shall be as shown in Figure 1Figure 1,, Type A or Type B test specimen, to
suit the plate thickness of the base material.
R
L
c
Unit (mm)
Type of specimen d0 Lc R
Type A 12,5 60 ≤ 15 ≤
Type B 6 32 ≤ 6 ≤
Key
d original diameter of the parallel length of a circular specimen
L parallel length
c
R radius of shoulder
d original diameter of the parallel length of a circular specimen
L parallel length
c
R radius of shoulder
Figure 1 — Schematic of weld metal longitudinal tensile strength test specimen
5.2.1.2 Impact test specimens
Test specimen designation is expressed using VWT and VHT according to ISO 9016. Size and tolerance shall
be in accordance with ISO 148-1.
5.2.2 Specimen location, notch orientation and number of specimens
5.2.2.1 General
Test specimens shall be taken in accordance with 5.2.2.25.2.2.2 and 5.2.2.35.2.2.3. Location for extraction of
mechanical test specimen shall be in accordance with Figure 2Figure 2.
The specific requirements for each welded joint apply:
a) a) The specimens for longitudinal tensile test shall be extracted from a location of the weld metal,
if the entire cross-section of the joint is welded with single process. If welded with multiple processes, the
test specimens shall be extracted from the location of each weld metal made by the respective welding
process.
b) b) The specimens for impact test shall be extracted from the vicinity of a location that could be
the point of fracture origin.
c) c) For beam flange to through diaphragm weld, beam flange to column weld, or beam to beam
weld, in the case of shop welding where the upper flange and lower flange are welded by the same welding
d
o
parameters with a metal backing plate placed on an inner side of beam joint, the specimens shall be
extracted from the weld metal of either the upper or lower flange.
In the case of site welding that is performed with a metal backing plate placed on an outer side of the beam
joint for lower flange welding, the specimens shall be extracted from the weld metals of both upper and
lower flanges, because the welding parameters differ between the upper and lower flanges.
d) d) Test specimens may be taken from full-scale test piece of the joints or simplified test pieces
made from plate-to-plate or tube-to-tube groove welds with steel materials actually used in the structure.
When simplified test pieces are used, the impact test specimens shall be taken from the locations specified
by the type of joint being simulated (upper flange or lower flange).
Dimensions in millimetres
25 25
25 25
a) Beam flange to through diaphragm weld, beam flange to b) Square steel tube column to diaphragm weld, or column to
column weld, or beam to beam weld column weld
2t 2t
5 4
2t
1 25
2t
c) Welded built-up box section column d) H-column to diaphragm weld, or column to column weld
t + 80 t + 80
t
2t 2t
t
e) Circular steel tube column to diaphragm weld or column f) Inner diaphragm for welded built-up box section column
to column weld (ESW)
300 300
g) Welded built-up box section column
(corner welding)
200 200
h) Welded built-up H-beam and H-column (T-joint, groove welding)
Key
1 location for extraction of mechanical test specimen
2 beam flange
3 seam weld
4 flange
5 web
6 box column plate
Figure 2 — Location for mechanical test specimens
5.2.2.2 Tensile test specimen
Tensile test specimens shall be taken in accordance with Table 2Table 2 and Figure 3Figure 3.
If a test joint is welded with multiple processes, tensile test specimens shall be extracted from locations that
can yield complete specimens with the reduced section completely in weld metal deposited by each single
process.
Table 2 — Tensile test specimen location and number of specimen
Nominal Location
thickness of
Type of
Number of Distance
base metal
Type of welded joint specimen
specimens
b b, f
a a y y Figure
t specimen
mm
mm
Single-bevel-groove, Butt joint (Including single-V-groove)
c c
Beam flange to through 9 ≤ t t ˂ 20 Type B 0,5t
1 specimen from
diaphragm, Beam to beam
upper or lower flange
c c b
20 ≤ t t ≤ 100 Type A 10
(shop welding)
c c
1 specimen from 9 ≤ t t ˂ 20 Type B 0,5t
Beam flange to through
upper and lower
diaphragm, Beam to beam
flange each (total 2
c c b
20 ≤ t t ≤ 100 Type A 10
(field welding)
specimens)
Figure 3
Figure 3
d d
Column to column 9 ≤ t t ˂ 20 Type B 0,5t
a)
(Welded built-up box section
1 specimen
d d b
column, Square or rectangular
20 ≤ t t ≤ 100 Type A 10
steel tube, H-column)
d d, h b
16 ≤ t t ˂ 30 Type B 10
Column to column
1 specimen d d, h
30 ≤ t t ≤
b
(Circular steel tube)
Type A 15
Single-bevel-groove, T-joint and corner joint (Including single-V-groove corner joint)
e e
9 ≤ t t ˂ 20 Type B 0,5t
Beam flange to column
1 specimen from
upper or lower flange e e b
(shop welding)
20 ≤ t t ≤ 100 Type A 10
e e
1 specimen from 9 ≤ t t ˂ 20 Type B 0,5t
Beam flange to column
upper and lower
flange each (total 2 e e b
(field welding)
20 ≤ t t ≤ 100 Type A 10
Figure 3
specimens)
Figure 3
d d
9 ≤ t t ˂ 20 Type B 0,5t b)
Column to through diaphragm
1 specimen
d d b
(Square steel tube, H-column)
20 ≤ t t ≤ 60 Type A 10
d d, h b
16 ≤ t t ˂ 30 Type B 10
Column to through diaphragm
1 specimen excluded
d d, h
30 ≤ t t ≤
seam weld of tube
(Circular steel tube) b
Type A 15
Nominal Location
thickness of
Type of
Number of Distance
base metal
Type of welded joint specimen
specimens b b, f
a a y y Figure
t specimen
mm
mm
Single process
b
22 ≤ t ≤ 100 Type A 10
1 specimen
Figure
Welded built-up box section
Multiple process 3
Figure 3
column b
1 specimen from each c)
50 ≤ t ≤ 100 Type A
f
process (total 2 20
specimens)
Square-groove, T-joint
Figure
Inner diaphragm for welded Centre of
g g
1 specimen 22 ≤ t t ≤ 100 Type A 3Figure
built-up box section column weld metal
3 d)
Double-bevel-groove, T-joint
22 ≤ t ˂ 28 Type B Figure 3
Welded built-up H-beam and Centre of
1 specimen Figure 3
H-column weld metal
28 ≤ t ≤ 40 Type A
e)
a See 5.2.1.15.2.1.1.
b Distance from the weld joint face side to the centre of specimen, y
F.
c Thickness of the thinner of the two welded plates.
d Thickness of column.
e Thickness of beam flange.
f Distance from the centre of specimen to the weld joint face of root side, yR.
g Thickness of box column plate.
h Outer diameter of circular steel tube; 400 mm or more.

t
y
F
y 3
F
t
a) Single-bevel-groove, Butt joint
3 t
y
F
y
F
t
b) Single-bevel-groove, T-joint
y
y
F
F
6 6
t
t
y
R
t t
9 9
c) Single-bevel-groove, corner joint (single or multiple process)
t
W
t
0.5t
t
S
0.5s
s
d) Square-groove, T-joint e) Double-bevel-groove, T-joint
Key
1 through diaphragm
2 beam flange
3 column
4 inner diaphragm
5 box column plate
6 box column plate (flange)
7 box column plate (web)
8 H-beam web
9 reference line, which indicates the centre line of the groove at the position of the test specimen
t thickness of beam flange or column plate
t thickness of beam web
w
yF distance from the centre of specimen to the weld joint face side
tS thickness of box column plate
s distance from the weld root to the bead toe
1 through diaphragm
2 beam flange
3 column
4 inner diaphragm
5 box column plate
6 box column plate (flange)
7 box column plate (web)
8 H-beam web
9 reference line, which indicates the centre line of the groove at the position of the test specimen
t thickness of beam flange or column plate
t thickness of beam web
w
y distance from the centre of specimen to the weld joint face side
F
t thickness of box column plate
S
s distance from the weld root to the bead toe
Figure 3 — Location of test specimens for tensile test
5.2.2.3 Impact test specimens
Impact test specimens shall be taken in accordance with Table 3Table 3 and Figure 4Figure 4. Three
specimens shall be extracted from each location of weld metal.
Table 3 — Location and notch position of impact test specimens
Notch Nominal
Distance
thickness of
e e, j
Distance
base metal
Type of welded joint Location
Denomination
y
t
(ISO 9016)
mm
mm
Single-bevel-groove, Butt joint (Including single-V-groove)
f f
VWT 0/y 12 ≤ t t ˂ 14 t / 2
Beam flange to through
VHT 0/y
Figure 4
upper or
Figur
a a
diaphragm, Beam to beam
y
e 4 a) f f e
lower flange
14 ≤ t t ≤ 100 7
(shop welding)
VHT 1/y
b b
y
f f
VWT 0/y 12 ≤ t t ˂ 14 t / 2
VHT 0/y
Figure 4
upper Figur
a a
y
flange e 4 a)
f f e
14 ≤ t t ≤ 100 7
VHT 1/y
upper
Beam flange to through
b b
y
and
diaphragm, Beam to beam
lower
f f
VWT 0/y 12 ≤ t t ˂ 14 t / 2
(field welding)
flanges
VHT 0/y
Figure 4
lower Figur
a a
y
flange e 4 b)
f f j
14 ≤ t t ≤ 100 7
VHT 1/y
b b
y
h h
VWT 0/y 9 ≤ t t ˂ 20 t / 2
Column to column
VHT 0/y Figure 4Fig
(Welded built-up box section
h h
a a 20 ≤ t t ≤
y ure 4 c)
e
column, S
...