ASTM D6555-23
(Guide)Standard Guide for Evaluating System Effects in Repetitive-Member Wood Assemblies
Standard Guide for Evaluating System Effects in Repetitive-Member Wood Assemblies
ABSTRACT
This guide identifies the variables to consider when evaluating the performance of repetitive-member wood assemblies for parallel framing systems. This guide discusses general approaches to quantifying an assembly adjustment including limitations of methods and materials when evaluating repetitive-member assembly performance, and does not address the techniques for modeling or testing of such.
SCOPE
1.1 This guide identifies variables to consider when evaluating repetitive-member assembly performance for parallel framing systems.
1.2 This guide defines terms commonly used to describe interaction mechanisms.
1.3 This guide discusses general approaches to quantifying an assembly adjustment including limitations of methods and materials when evaluating repetitive-member assembly performance.
1.4 This guide does not detail the techniques for modeling or testing repetitive-member assembly performance.
1.5 The analysis and discussion presented in this guideline are based on the assumption that a means exists for distributing applied loads among adjacent, parallel supporting members of the system.
1.6 Evaluation of creep effects is beyond the scope of this guide.
1.7 This guide does not purport to suggest or establish appropriate safety levels for assemblies, but cautions users that designers often interpret that safety levels for assemblies and full structures should be higher than safety levels for individual structural members.
Note 1: Methods other than traditional safety factor approaches, such as reliability methods, are increasingly used to estimate the probability of failure of structural elements. However, the extension of these methods to assemblies or to complete structures is still evolving. For example, complete structures will likely exhibit less variability than individual structural elements. Additionally, there is a potential for beneficial changes in failure modes (that is, more ductile failure modes in systems). These considerations are beyond the scope of this guide.
1.8 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.10 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6555 − 23
Standard Guide for
Evaluating System Effects in Repetitive-Member Wood
1
Assemblies
This standard is issued under the fixed designation D6555; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The apparent stiffness and strength of repetitive-member wood assemblies is generally greater than
the stiffness and strength of the members in the assembly acting alone. The enhanced performance is
a result of load sharing, partial composite action, and residual capacity obtained through the joining
of members with sheathing or cladding, or by connections directly. The contributions of these effects
are quantified by comparing the response of a particular assembly under an applied load to the
response of the members of the assembly under the same load. This guide defines the individual effects
responsible for enhanced repetitive-member performance and provides general information on the
variables that should be considered in the evaluation of the magnitude of such performance.
The influence of load sharing, composite action, and residual capacity on assembly performance
varies with assembly configuration and individual member properties, as well as other variables. The
relationship between such variables and the effects of load sharing and composite action is discussed
in engineering literature. Consensus committees have recognized design stress increases for
assemblies based on the contribution of these effects individually or on their combined effect.
The development of a standardized approach to recognize “system effects” in the design of
repetitive-member assemblies requires standardized analyses of the effects of assembly construction
and performance. Users are cautioned to understand that the performance improvements that might be
observed in system testing are often related to load paths or boundary conditions in the assembly that
differ from those of individual members. This is especially true for relatively complex assemblies. For
such assemblies, users are encouraged to design the test protocols such that internal load paths, as well
as summations of “loads in” versus “loads out” are measured (see X3.11.7.1). Data from testing,
preferably coupled with analytical predictions, provide the most effective means by which system
factors can be developed. When system factors are intended to apply to strength (rather than being
limited to stiffness), loads must be applied to produce failures so that the effects of nonlinearities or
changes in failure modes can be quantified.
1. Scope 1.4 This guide does not detail the techniques for modeling
or testing repetitive-member assembly performance.
1.1 This guide identifies variables to consider when evalu-
ating repetitive-member assembly performance for parallel
1.5 The analysis and discussion presented in this guideline
framing systems.
are based on the assumption that a means exists for distributing
1.2 This guide defines terms commonly used to describe
applied loads among adjacent, parallel supporting members of
interaction mechanisms.
the system.
1.3 This guide discusses general approaches to quantifying
1.6 Evaluation of creep effects is beyond the scope of this
an assembly adjustment including limitations of methods and
guide.
materials when evaluating repetitive-member assembly perfor-
mance.
1.7 This guide does not purport to suggest or establish
appropriate safety levels for assemblies, but cautions users that
1
This guide is under the jurisdiction of ASTM Committee D07 on Wood and is
designers often interpret that safety levels for assemblies and
the direct responsibility of Subcommittee D07.05 on Wood Assemblies.
full structures should be higher than safety levels for individual
Current edition approved Oct. 1, 2023. Published October 2023. Originally
structural members.
approved in 2000. Last previous edition approved in 2017 as D6555 – 17. DOI:
10.1520/D6555-23.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D6555 − 23
NOTE 1—Methods other than traditional safety factor approaches, such
3.1.1 composite action, n—interaction of two or more con-
as reliability methods, are increasingly used to estimate the probability of
nected wood members that increases the effective section
failure of structural elements. However, the extension of these me
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6555 − 17 D6555 − 23
Standard Guide for
Evaluating System Effects in Repetitive-Member Wood
1
Assemblies
This standard is issued under the fixed designation D6555; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The apparent stiffness and strength of repetitive-member wood assemblies is generally greater than
the stiffness and strength of the members in the assembly acting alone. The enhanced performance is
a result of load sharing, partial composite action, and residual capacity obtained through the joining
of members with sheathing or cladding, or by connections directly. The contributions of these effects
are quantified by comparing the response of a particular assembly under an applied load to the
response of the members of the assembly under the same load. This guide defines the individual effects
responsible for enhanced repetitive-member performance and provides general information on the
variables that should be considered in the evaluation of the magnitude of such performance.
The influence of load sharing, composite action, and residual capacity on assembly performance
varies with assembly configuration and individual member properties, as well as other variables. The
relationship between such variables and the effects of load sharing and composite action is discussed
in engineering literature. Consensus committees have recognized design stress increases for
assemblies based on the contribution of these effects individually or on their combined effect.
The development of a standardized approach to recognize “system effects” in the design of
repetitive-member assemblies requires standardized analyses of the effects of assembly construction
and performance. Users are cautioned to understand that the performance improvements that might be
observed in system testing are often related to load paths or boundary conditions in the assembly that
differ from those of individual members. This is especially true for relatively complex assemblies. For
such assemblies, users are encouraged to design the test protocols such that internal load paths, as well
as summations of “loads in” versus “loads out” are measured (see X3.11.7.1). Data from testing,
preferably coupled with analytical predictions, provide the most effective means by which system
factors can be developed. When system factors are intended to apply to strength (rather than being
limited to stiffness), loads must be applied to produce failures so that the effects of nonlinearities or
changes in failure modes can be quantified.
1. Scope
1.1 This guide identifies variables to consider when evaluating repetitive-member assembly performance for parallel framing
systems.
1.2 This guide defines terms commonly used to describe interaction mechanisms.
1
This guide is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.05 on Wood Assemblies.
Current edition approved Nov. 1, 2017Oct. 1, 2023. Published November 2017October 2023. Originally approved in 2000. Last previous edition approved in 20142017
as D6555 – 03D6555 – 17.(2014). DOI: 10.1520/D6555-17.10.1520/D6555-23.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D6555 − 23
1.3 This guide discusses general approaches to quantifying an assembly adjustment including limitations of methods and materials
when evaluating repetitive-member assembly performance.
1.4 This guide does not detail the techniques for modeling or testing repetitive-member assembly performance.
1.5 The analysis and discussion presented in this guideline are based on the assumption that a means exists for distributing applied
loads among adjacent, parallel supporting members of the system.
1.6 Evaluation of creep effects is beyond the scope of this guide.
1.7 This guide does not purport to suggest or establish appropriate safety levels for assemblies, but cautions users that designers
often interpret that safety levels for assemblies and full structures should be higher than safety levels for individual structural
members.
2
---------------------- Page: 2 ----------------------
D6555 − 23
NOTE 1—Methods other than traditional safety factor approaches,
...
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