ISO/TR 21141:2022
(Main)Timber structures — Timber connections and assemblies — Determination of yield and ultimate characteristics and ductility from test data
Timber structures — Timber connections and assemblies — Determination of yield and ultimate characteristics and ductility from test data
The purpose of this document is to extract the methods for determining the yield and ultimate characteristics and ductility of joints and assemblies from test data by reviewing existing standards in Europe, North America and Far East Asia and to provide the basic data for unifying the evaluation methods of parameters by clarifying their similarities and differences. These parameters are applied for determining the seismic performance of timber structures. This document deals with the method for determining the mechanical properties of individual joints and assemblies, and it does not refer to the seismic performance of the entire structure.
Structures en bois — Assemblages et composants bois — Détermination des caractéristiques limites et ultimes et de la ductilité à partir des données d’essai
General Information
Relations
Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 21141
First edition
2022-05
Timber structures — Timber
connections and assemblies —
Determination of yield and ultimate
characteristics and ductility from test
data
Structures en bois — Assemblages et composants bois —
Détermination des caractéristiques limites et ultimes et de la ductilité
à partir des données d’essai
Reference number
ISO/TR 21141:2022(E)
© ISO 2022
---------------------- Page: 1 ----------------------
ISO/TR 21141:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022
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
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO 2022 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 21141:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.2
5 Determination of envelope curves.3
6 Determination of elastic stiffness . 3
7 Determination of yield point . 5
7.1 Determination of yield load . 5
7.2 Determination of yield displacement . 7
8 Determination of ultimate limit state . 7
8.1 Ultimate (failure) displacement . 7
8.2 Ultimate (failure) load . 7
8.3 Equivalent energy elastic-plastic load and stiffness. 8
9 Determination of ductility factor . 9
Annex A (informative) Examples of modelling of envelope curves.10
Annex B (informative) Examples of test data .12
Annex C (informative) Impairment of strength and energy dissipation .36
Bibliography .38
iii
© ISO 2022 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/TR 21141:2022(E)
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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
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 165, Timber 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
© ISO 2022 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TR 21141:2022(E)
Introduction
Timber shows generally brittle failure in tension and bending. This characteristic of wood may cause
serious damage to buildings due to the lack of energy dissipation during an earthquake. To avoid such
damage, it is expected that the joints connecting wooden members dissipate seismic energy instead
of the members themselves. Ductility of a structure is one of the most important factors in dissipating
seismic energy. In this technical report, the definitions of yield point, ultimate characteristics and
ductility factor used in various test standards are reviewed and methods of determining these
characteristics from quasi-static and reversed-cyclic loading test data are compared.
Better fits to envelope curves derived from testing, such as more detailed piecewise linearization
are permissible, and indeed desirable for whole building design. The derived load-deflection inputs
to structural analysis programs of the various structural elements are only applicable to the case of
assessing the maximum connection forces under earthquake loading and provide no guarantee that a
structure will remain stable beyond the ultimate strength of the system.
v
© ISO 2022 – All rights reserved
---------------------- Page: 5 ----------------------
TECHNICAL REPORT ISO/TR 21141:2022(E)
Timber structures — Timber connections and assemblies
— Determination of yield and ultimate characteristics and
ductility from test data
1 Scope
The purpose of this document is to extract the methods for determining the yield and ultimate
characteristics and ductility of joints and assemblies from test data by reviewing existing standards
in Europe, North America and Far East Asia and to provide the basic data for unifying the evaluation
methods of parameters by clarifying their similarities and differences.
These parameters are applied for determining the seismic performance of timber structures. This
document deals with the method for determining the mechanical properties of individual joints and
assemblies, and it does not refer to the seismic performance of the entire structure.
2 Normative references
There are no normative references in this document.
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
envelope curve
locus of extremities of the load-displacement hysteresis loops, either obtained separately for the
positive and negative loading directions, or obtained by averaging the absolute values of load and
displacement of the corresponding positive and negative envelope points for each cycle in the case of a
reversed cyclic loading test (see Clause 5)
3.2
stiffness
K
e
resistance to deformation of a specimen in the elastic range, which can be expressed as a slope measured
by the ratio of the resisted load, F , to the corresponding displacement, V (see Clause 6)
1 1
3.3
elastic range
stress range in which a material, upon unloading, will recover the deformation caused by the application
of a stress or force
3.4
yield point
point at which a joint or an assembly begins to deform plastically
1
© ISO 2022 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/TR 21141:2022(E)
3.5
yield load and displacement
F , V
y y
load and displacement corresponding to the yield point (3.4) (see 7.1)
3.6
maximum load
F
max
maximum value of the load recorded in a quasi-static test or the maximum value of the load on the
average envelope curve (3.1) in a reversed-cyclic test or the absolute maximum values of the load
recorded in positive and negative directions
3.7
ultimate limit state
failure limit state
state at which a joint or an assembly undergoes a sudden load drop or the load decreases gradually to
80 % of the maximum load (3.6), F , or an excessive deformation (displacement or rotation) occurs
max
(see 8.1 and 8.2)
3.8
ultimate displacement
V
u
failure displacement
displacement corresponding to the ultimate limit state (3.7) (see 8.1).
3.9
equivalent energy elastic-plastic curve
EEEP
ideal elastic-plastic curve circumscribing an area equal to the area enclosed by the envelope curve (3.1)
between the origin, the ultimate displacement (3.8), V , and the displacement axis (see 8.3)
u
3.10
equivalent energy elastic-plastic load
F
eeep
load corresponding to the upper limit of the equivalent energy elastic-plastic curve, EEEP, (3.9)
3.11
ductility
ability of joints or assemblies to undergo large amplitude displacement in the plastic range without a
substantial reduction of strength
3.12
ductility factor
μ
ratio between ultimate displacement (3.8), V , and yield displacement, V , (see Clause 9).
u y
3.13
equivalent energy elastic-plastic ductility factor
μ
eeep
ratio between ultimate displacement (3.8), V , and EEEP displacement, V , (see Clause 9).
u eeep
4 Symbols and abbreviated terms
The following symbols and units apply.
F , F any load within the elastic range of the curve, expressed in Newtons
1 2
F equivalent energy elastic-plastic (EEEP) load, expressed in Newtons
eeep
2
© ISO 2022 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TR 21141:2022(E)
F equivalent energy bilinear ultimate load, expressed in Newtons
eebl
F maximum load, expressed in Newtons
max
F yield load, expressed in Newtons
y
F ultimate (failure) load, expressed in Newtons
u
K elastic stiffness, expressed in Newtons per millimetre
e
K equivalent energy elastic-plastic stiffness, expressed in Newtons per millimetre
eeep
V , V displacement corresponding to F , F within the elastic range, expressed in millimetres
1 2 1 2
V equivalent energy elastic-plastic yield displacement, expressed in millimetres
eeep
V yield displacement, expressed in millimetres
y
V ultimate (failure) displacement, expressed in millimetres
u
μ ductility factor
μ equivalent energy elastic-plastic ductility factor
eeep
5 Determination of envelope curves
The initial envelope curve for the reversed-cyclic tests is established by connecting the peak loads and/
or the peak displacements from the first cycle of each phase of the cyclic loading, whichever better
represents the backbone shape of the hysteretic response. The points on the hysteresis loops where the
absolute value of the displacement at the peak load is less than that in the previous phase are replaced
with points that better represent the hysteretic response.
The envelope curves for the second and subsequent reversed cycles of each phase may be also
established if necessary.
If the load-displacement relation is (point) symmetric, envelope curve may be obtained by averaging the
absolute values of load and displacement of the corresponding positive and negative envelope points for
each cycle (see examples in B.1, B.5, B.6 and B.7).
For joints and assemblies producing asymmetric response, the positive and negative envelopes are
analysed separately (see examples B.2, B.3, and B.4).
NOTE In Annex B, positive and negative envelope curves are obtained separately if the values of maximum
(peak) load or displacement in the positive hysteresis loops in each phase up to the ultimate displacement, V ,
u
differ more than 20 % from the absolute value of those obtained from the corresponding negative hysteresis
loops.
6 Determination of elastic stiffness
Initial stiffness of joints or assemblies, K , is determined by the line (a) in Figures 1 a) to 1 d).
e
Figure 1 a) shows an idealized case where the load-displacement (or envelope) curve starts at the origin
and is linear in the elastic range. The load, F , and the corresponding displacement, V , can be taken
1 1
anywhere within the elastic range of the curve (see examples in B.1.2 and B.3.2).
Figure 1 b) shows schematically a case of a load-displacement (or envelope) curve with initial slip
(horizontal offset) due to slack in the joint or assembly, due to load delay or other reasons. Depending
on the reasons, the initial slip may be neglected in the determination of the initial stiffness, as shown
in Figure 1 b). However, if the slack is inherent to the performance of the joint or assembly, it is
recommended to not neglect it (see example B.2.2).
3
© ISO 2022 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/TR 21141:2022(E)
Figure 1.C shows schematically a case of a load-displacement (or envelope) curve with an infinite initial
stiffness (vertical offset) due to preload or initial friction in the joint or assembly or other reasons.
Depending on the reasons, the offset may be neglected in the determination of the initial stiffness, as
shown in Figure 1 c). However, if the high initial stiffness is inherent to the performance of the joint or
assembly, it is recommended to not neglect it (see example B.4.2).
Figure 1 d) shows schematically a case of a load-displacement (or envelope) curve without distinct
linear portion in the elastic range. In this case, the initial stiffness may be approximated by the slope
of a straight line connecting the points between 0,1 and 0,4 times the maximum load, F . Linear
max
regression may be used to determine the slope of the line (see example in B.6.2).
NOTE 1 If the straight line connecting the points between 0,1 and 0,4 F does not fit the load-displacement
max
(or envelope) curve, this range is not appropriate. Some joints (e.g., with multiple fasteners) produce S-shape
load-displacement (or envelope) curves where linear regression in the range 0,1 to 0,4 F is not appropriate,
max
because the initial take-off can go beyond 0,1 F and the maximum stiffness (the steepest slope) is achieved
max
beyond 0,4 F . Also, the 0,4 F limit is not appropriate when the initial yielding starts below 0,4 F . It can
max max max
be observed either in joints with multiple fasteners or where the yield mode is overridden by another failure
mode (e.g., tear-through or head pull through). In these cases, ranges other than 0,1 to 0,4 can be appropriate.
NOTE 2 Stiffness for determination of the equivalent energy elastic-plastic curve (K ) can be determined
eeep
differently (see 8.3).
NOTE 3 ISO 6891 will be referred to determine the elastic stiffness in case of the quasi static test.
a) Idealised stiffness b) Stiffness with initial slip
4
© ISO 2022 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/TR 21141:2022(E)
c) Stiffness with initial friction d) Stiffness without linear part
Figure 1 — Examples of elastic stiffness
7 Determination of yield point
7.1 Determination of yield load
Yield load, F , is determined by one of the following methods according to the relevant standard.
y
Method A1 [EN 12512]: When the load-displacement (or envelope) curve presents two well-defined
linear parts, the yield load, F , is determined by the intersection of these two lines (lines (a) and (c) in
y
Figure 2 a)).
Method A2 [EN 12512]: When the load-displacement (or envelope) curve does not present well-defined
linear parts, the yield load, F , is determined by the intersection of two straight lines: the first line-
y
connecting the points between 0,1 and 0,4 times the maximum load, F , and the second line having
max
the tangent of a slope of 1/6 of the first line (lines (a) and (d) in Figure 2 b)) (see Figures B.2 and B.8).
NOTE 1 EN 12512 intends to apply this method to determine the yield load for timber joints. It has not been
confirmed if this method is applicable to determine the yield load of assemblies such as shear walls. It tends to
give a higher value than JIS A1414-2 in cases of wood-based shear walls (see Figures B.14 c) and B.20 c)).
NOTE 2 The determined yield load is affected by the slope of the first line as the slope of the second line is
determined also according to the slope of the first line. This tendency is more significant when the slope of the
first line is low and the envelope curve is convexly rounded after the yielding (see Figure B.5 d)).
Method A3 [JIS A1414-2]: When the load-displacement (or envelope) curve does not present well-
defined linear parts, the yield load, F , is determined by the intersection of two straight lines: the first
y
line connecting the points between 0,1 and 0,4 times the maximum load, F , (line (a) in Figure 2 c)) and
max
the second line (line (f) in Figure 2 c)) determined as a tangent to the load-displacement (or envelope)
curve and parallel to the line connecting two points corresponding to 0,4 and 0,9 times the maximum
load (F ) (line (e) in Figure 2 c)) (see Figure B.20 b)).
max
NOTE 1 JIS A1414-2 intends to apply this method to determine the yield load of shear walls. However, this
method is applied also to determine the yield load of timber joints.
5
© ISO 2022 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/TR 21141:2022(E)
NOTE 2 If the load-displacement (or envelope) curve is concavely curved and there is no appropriate
intersection of lines (a) and (f), the ranges 0,1 to 0,4 and 0,4 to 0,9 times the maximum load, F , are not
max
appropriate.
Method A4 [ASTM D5652]: For joints with dowel-type fasteners, the yield load, F , is determined
y
as follows. Fit a straight line to the initial linear part of the load-displacement (or envelope) curve,
offset this line by a displacement equal to 5 % of the nominal fastener diameter (or the measured
fastener diameter if the nominal diameter is not determined), and select the load at which the offset
line intersects the load-displacement curve (see line (a') in Figure 2 d)). If the initial part of the load-
displacement (or envelope) curve is nonlinear, use the straight line connecting the points between 0,1
and 0,4 times the maximum load, F , (see Figures B.4 and B.11 c)).
max
NOTE 1 ASTM D5652 intends to apply this method to determine the yield point of a single-bolt joint. This
method is applicable to joints with other types of single dowels such as nails and screws, but it does not apply
directly to other types of joints and assemblies such as shear walls. However, it can be applied if the offset
criterion is agreed upon.
NOTE 2 In the case where the offset line does not intersect the load-displacement (or envelope) curve, the
yield load is not determined.
a) Determination of yield load by lines (a) b) Determination of yield load by lines (a) and
and (c) (d)
c) Determination of yield load by lines (a) d) Determination of yield load by line (a')
and (f)
6
© ISO 2022 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/TR 21141:2022(E)
Key
a
5 % off-set of bolt diameter.
Figure 2 — Determination of yield load
7.2 Determination of yield displacement
Yield displacement, V , is determined as the displacement at the intersection point of two lines
y
determined for Method A1 or Method A2 (see 7.1) (Figures 2 a) and 2 b)).
Yield displacement, V , is determined as the displacement corresponding to the yield load, F , on the
y y
load-displacement (or envelope) curve for Method A3 or Method A4 (see 7.1) (Figures 2 c) and 2 d)).
8 Determination of ultimate limit state
8.1 Ultimate (failure) displacement
Ultimate (failure) displacement, V , is determined as one of the following, whichever occurs first (see
u
Figure 3):
Case (1): displacement corresponding to the ultimate limit state caused by a sudden load drop.
Case (2): displacement corresponding to the ultimate limit state caused by a gradual decrease of load to
0,8F after the maximum load, F , is achieved.
max max
Case (3): displacement 30 mm for joints and rotation or shear deformation angle 1/15 rad. for assemblies
(e.g., moment resisting joints, shear walls, etc.).
8.2 Ultimate (failure) load
Ultimate (failure) load, F , is determined as one of the following, whichever occurs first (see Figure 3):
u
Case (1): load recorded at the point immediately preceding the load drop (F ≥ F ≥ 0,8F ).
max u max
Case (2): 0,8 times maximum load, F , in case of a gradual load decrease after the maximum load
max
(F = 0,8F ).
u max
Case (3): load corresponding to the ultimate displacement 30 mm for joints and rotation or shear
deformation angle 1/15 rad. for assemblies in case of an excessive deformation.
7
© ISO 2022 – All rights reserved
---------------------- Page: 12 ----------------------
ISO/TR 21141:2022(E)
Key
a
Case (1).
b
Case (2).
c
Case (3).
d
(30 mm or 1/15 rad.).
Figure 3 — Definition of ultimate displacement, V
u
8.3 Equivalent energy elastic-plastic load and stiffness
Equivalent energy elastic-plastic (EEEP) curve is determined by equating the area, A, under the load-
displacement (or envelope) curve up to the ultimate displacement, V , and the area limited by the
u
straight lines: line (b) representing the equivalent energy elastic-plastic stiffness, K , and line (g)
eeep
representing the equivalent energy elastic-plastic load, F , up to the ultimate displacement, V , (see
eeep u
Figures 4 a) and 4 b)).
Equivalent energy elastic-plastic load, F , is calculated using Formula (1):
eeep
2A
2
FV=− V − K (1)
eeep uu eeep
K
eeep
2A
2
If V < , it is permitted to take F = 0,85F .
u eeep max
K
eeep
Equivalent energy elastic-plastic stiffness, K , is determined using one of the following methods.
eeep
Method B1 [ASTM E2126]: The equivalent energy elastic-plastic stiffness, K , is determined by a
eeep
straight line passing through the origin and 0,4F on the load-displacement (or envelope) curve (see
max
Figures 4 a) and B.18 a)).
Method B2 [JIS A1414-2]: The equivalent energy elastic-plastic stiffness, K , is determined by a
eeep
straight line passing through the origin and the yield point on the load-displacement (or envelope)
curve determined using Method A3 (see 7.1) (see Figures 4 b) and B.18 b)).
NOTE 1 Method B1 tends to give smaller V and consequently larger μ than Method B2(see examples in
eeep eeep
B.5.3, B.6.3 and B.7.3).
8
© ISO 2022 – All rights reserved
---------------------- Page: 13 ----------------------
ISO/TR 21141:2022(E)
NOTE 2 If the equivalent energy elastic-plastic model does not produce satisfactory results, an equivalent
energy bi-linear model can be applied. In this case, the equivalent energy bilinear ultimate load, F ,can be
eebl
determined so that the area limited by the bi-linear curve up to the ultimate displacement equals the area limited
by the load-displacement (or envelope) curve (see example in A.2).
a) Determination of the EEEP stiffness b) Determination of the EEEP stiffness (K )
eeep
(K )(line (b)) and the EEEP load (F ) (line (b)) and the EEEP load (F ) (line (g))
eeep eeep eeep
(line (g))
Figure 4 — Determination of the EEEP stiffness
9 Determination of ductility factor
Ductility factor is determined using one of the following methods.
Method C1 [EN 12512]: Ductility factor, μ, is calculated from Formula 2 as the ratio of the ultimate
displacement, V , (see 8.1) to the yield displacement, V , (see 7.2)(see Figure A.1).
u y
μ =VV/ (2)
uy
Method C2 [ASTM E2126, JIS A1414-2]: Equivalent energy elastic-plastic ductility factor, μ , is
eeep
calculated from Formula 3 as the ratio of the ultimate displacement, V , (see8.1) to the equivalent
u
energy elastic-plastic yield displacement, V , (see Figures 4 a) and 4 b)).
eeep
μ =VV/ (3)
eeep u eeep
where, V is the displacement at the intersection of lines (b) and (g) in Figure 4.
eeep
NOTE 1 The relationship between μ and μ is expressed as follows:
eeep
F
y
μμ=
eeep
F
eeep
Examples of determination of the elastic stiffness, yield point, ultimate characteristics and ductility
factor for joints and assemblies are shown in Annex B.
Determination method of impairment of strength (strength degradation) and energy dissipation in
connections and assemblies are shown in Annex C.
9
© ISO 2022 – All rights reserved
---------------------- Page: 14 ----------------------
ISO/TR 21141:2022(E)
Annex A
(informative)
Examples of modelling of envelope curves
A.1 Elastic-plastic model
Most envelope curves can be modelled generally by elastic–plastic model as shown in Figure A.1. This
model determines the ratio, R , of the linear force response, F , to the ultimate capacity of the joints
eeep 0
or assemblies, F , which has the equivalent energy dissipation in elastic-plastic model as shown in
eeep
Figure A.1. The value of R is the ratio of the linear seismic response to non-linear response and
eeep
expressed as follows by using equivalent energy elastic-plastic ductility factor, μ .
eeep
F
0
R == 21μ −
eeep eeep
F
eeep
The ratio, R , defined by the ratio F to F is determined by using the ductility factor, μ, and strength
y 0 y
ratio, r .
u
F
0
R == rr2μ−
()
y uu
F
y
μ==VV// rF F
uy uyeeep
where F is the maximum linear force response.
0
Figure A.1 — Linear response and response by elastic-plastic model
A.2 Bi-linear model
In case the envelope curve is modelled by bi-linear model, the inclination of the second line (g) is
determined so that the area surrounded by the lines (b), (g), (h) and displacement axis equals to the
area surrounded by the envelope curves as shown in Figure A.2. This model determines the ratio, R ,
y
defined by the ratio of the linear force response, F , to the yield strength, F , of the joints or assemblies
0 y
10
© ISO 2022 – All rights reserved
---------------------- Page: 15 ----------------------
ISO/TR 21141:2022(E)
which has the equivalent energy dissipation in bi-linear model. The value of R is expressed as follows
y
by using ductility factor, μ, and strength ratio, r .
u
F
0
R == ()rr+ 1 ⋅μ−
y uu
F
y
where, rF= /F (F ≦ F )
uyeebl eebl max
where
F is the equivalent energy bi-linear ultimate load;
eebl
F is the maximum linear force response.
0
Figure A.2 — Example of modeling by bilinear model
11
© ISO 2022 – All rights reserved
---------------------- Page: 16 ----------------------
ISO/TR 21141:2022(E)
Annex B
(informative)
Examples of test data
B.1 General
Yield and ultimate characteristics and ductility of several joints and assemblies are determined from
test data with different evaluation methods presented in this technical report. These examples are
provided for understanding the effect of the determination methods on a particular load-displacement
re
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.