ASTM D6555-03(2014)
(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 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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Buy Standard
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D6555 − 03 (Reapproved 2014)
Standard Guide for
Evaluating System Effects in Repetitive-Member Wood
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.Anumber 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
responseofthemembersoftheassemblyunderthesameload.Thisguidedefinestheindividualeffects
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.
1. Scope 1.6 Evaluation of creep effects is beyond the scope of this
guide.
1.1 This guide identifies variables to consider when evalu-
1.7 This standard does not purport to address all of the
ating repetitive-member assembly performance for parallel
safety concerns, if any, associated with its use. It is the
framing systems.
responsibility of the user of this standard to establish appro-
1.2 This guide defines terms commonly used to describe
priate safety and health practices and determine the applica-
interaction mechanisms.
bility of regulatory limitations prior to use.
1.3 This guide discusses general approaches to quantifying
2. Referenced Documents
an assembly adjustment including limitations of methods and
materials when evaluating repetitive-member assembly perfor-
2.1 ASTM Standards:
mance.
D245Practice for Establishing Structural Grades and Re-
lated Allowable Properties for Visually Graded Lumber
1.4 This guide does not detail the techniques for modeling
D1990Practice for Establishing Allowable Properties for
or testing repetitive-member assembly performance.
Visually-Graded Dimension Lumber from In-Grade Tests
1.5 The analysis and discussion presented in this guideline
of Full-Size Specimens
arebasedontheassumptionthatameansexistsfordistributing
D2915Practice for Sampling and Data-Analysis for Struc-
applied loads among adjacent, parallel supporting members of
tural Wood and Wood-Based Products
the system.
D5055Specification for Establishing and Monitoring Struc-
tural Capacities of Prefabricated Wood I-Joists
This guide is under the jurisdiction ofASTM Committee D07 on Wood and is
the direct responsibility of Subcommittee D07.05 on Wood Assemblies. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Aug. 1, 2014. Published August 2014. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2000. Last previous edition approved in 2008 as D6555–03 (2008). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6555-03R14. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6555 − 03 (2014)
NOTE 1—Enhanced assembly performance due to intentional overde-
3. Terminology
sign or the contribution of elements not considered in the design are
3.1 Definitions:
beyond the scope of this guide.
3.1.1 composite action, n—interaction of two or more con-
nected wood members that increases the effective section
5. Load Sharing
properties over that determined for the individual members.
5.1 Explanation of Load Sharing:
3.1.2 element, n—a discrete physical piece of a member
5.1.1 Load sharing reduces apparent stiffness variability of
such as a truss chord.
memberswithinagivenassembly.Ingeneral,memberstiffness
3.1.3 global correlation, n—correlation of member proper- variabilityresultsinadistributionofloadthatincreasesloadon
ties based on analysis of property data representative of the stiffer members and reduces load on more flexible members.
species or species group for a large defined area or region 5.1.2 A positive strength-stiffness correlation for members
ratherthanmill-by-millorlot-by-lotdata.Thearearepresented
results in load sharing increases, which give the appearance of
may be defined by political, ecological, or other boundaries. higherstrengthforminimumstrengthmembersinanassembly
under uniform loads.
3.1.4 load sharing, n—distribution of load among adjacent,
parallel members in proportion to relative member stiffness.
NOTE 2—Positive correlations between modulus of elasticity and
strength are generally observed in samples of “mill run” dimension
3.1.5 member, n—a structural wood element or elements
lumber;however,noprocessiscurrentlyinplacetoensureorimprovethe
such as studs, joists, rafters, tresses, that carry load directly to
correlation of these relationships on a grade-by-grade or lot-by-lot basis.
assembly supports. A member may consist of one element or
Where design values for a member grade are based on global values,
multiple elements.
global correlations may be used with that grade when variability in the
stiffness of production lots is taken into account.
3.1.6 parallel framing system, n—a system of parallel fram-
ing members. 5.1.3 Load sharing tends to increase as member stiffness
variability increases and as transverse load-distributing ele-
3.1.7 repetitive-member wood assembly, n—a system in
ment stiffness increases. Assembly capacity at first member
which three or more members are joined using a transverse
failure is increased as member strength-stiffness correlation
load-distributing element.
increases.
3.1.7.1 Discussion—Exception: Two-ply assemblies can be
considered repetitive-member assemblies when the members
NOTE 3—From a practical standpoint, the system performance due to
are in direct side-by-side contact and are joined together by loadsharingisboundedbytheminimumperformancewhentheminimum
member in the assembly acts alone and by the maximum performance
mechanical connections or adhesives, or both, to distribute
when all members in the assembly achieve average performance.
load.
5.2 Variables affecting Load Sharing Effects on Stiffness
3.1.8 residual capacity, n—ratio of the maximum assembly
include:
capacity to the assembly capacity at first failure of an indi-
5.2.1 Loading conditions;
vidual member or connection.
5.2.2 Memberspan,endconditions,andsupportconditions;
3.1.9 sheathing gaps, n—interruptions in the continuity of a
5.2.3 Member spacing;
load-distributing element such as joints in sheathing or deck-
5.2.4 Variability of member stiffness;
ing.
5.2.5 Ratio of average transverse load-distributing element
3.1.10 transverse load-distributing elements, n—structural
stiffness to average member stiffness;
componentssuchassheathing,sidinganddeckingthatsupport
5.2.6 Sheathing gaps;
and distribute load to members. Other components such as
5.2.7 Number of members;
cross bridging, solid blocking, distributed ceiling strapping,
5.2.8 Load-distributing element end conditions;
strongbacks, and connection systems may also distribute load
5.2.9 Lateral bracing; and
among members.
5.2.10 Attachment between members.
5.3 Variables affecting Load Sharing Effects on Strength
4. Significance and Use
include:
4.1 This guide covers variables to be considered in the
5.3.1 Load sharing for stiffness (5.2), and
evaluation of the performance of repetitive-member wood
5.3.2 Level of member strength-stiffness correlation.
assemblies. System performance is attributable to one or more
of the following effects:
6. Composite Action
4.1.1 Load sharing,
6.1 Explanation of Composite Action:
4.1.2 Composite action, or
6.1.1 For bending members, composite action results in
4.1.3 Residual capacity.
increased flexural rigidity by increasing the effective moment
4.2 This guide is intended for use where design stress
ofinertiaofthecombinedcross-section.Theincreasedflexural
adjustments for repetitive-member assemblies are being devel-
rigidity results in a redistribution of stresses which usually
oped.
results in increased strength.
4.3 This guide serves as a basis to evaluate design stress 6.1.2 Partial composite action is the result of a non-rigid
adjustments developed using analytical or empirical proce- connection between elements which allows interlayer slip
dures. under load.
D6555 − 03 (2014)
6.1.3 Composite action decreases as the rigidity of the 8. Quantifying Repetitive-Member Effects
connection between the transverse load-distributing element
8.1 General—This section describes procedures for evalu-
and the member decreases.
ating the system effects in repetitive-member wood assemblies
6.2 Variables affecting Composite Action Effects on Stiff-
using either analytical or empirical methods. Analysis of the
ness include:
results for either method shall follow the requirements of 8.4.
6.2.1 Loading conditions,
8.2 Analytical Method:
6.2.2 Load magnitude,
8.2.1 System effects in repetitive-member wood assemblies
6.2.3 Member span,
shall be quantified using methods of mechanics and statistics.
6.2.4 Member spacing,
8.2.2 Each component of the system factor shall be consid-
6.2.5 Connection type and stiffness,
ered.
6.2.6 Sheathing gap stiffness and location in transverse
8.2.3 Confirmation tests shall be conducted to verify ad-
load-distributing elements, and
equacy of the derivation in 8.2.1 to compute force distribu-
6.2.7 Stiffness of members and transverse load-distributing
tions. Tests shall cover the range of conditions (that is,
elements (see 3.1.5).
variables listed in 5.2, 5.3, 6.2, 6.3, and 7.2) anticipated in use.
6.3 Variables affecting Composite Action Effects on
If it is not possible to test the full range of conditions
Strength include:
anticipatedinuse,theresultsoflimitedconfirmationtestsshall
6.3.1 Composite action for stiffness (6.2), and
be so reported and the application of such test results clearly
6.3.2 Location of sheathing gaps along members.
limited to the range of conditions represented by the tests.
Confirmation tests shall reflect the statistical assumptions of
7. Residual Capacity of the Assembly
8.2.1.
7.1 Explanation of Residual Capacity:
NOTE 6—When analyzing the results of confirmation tests, the user is
7.1.1 Residual capacity is a function of load sharing and
cautioned to differentiate between system effects in repetitive-member
composite action which occur after first member failure. As a
wood assemblies that occur prior to first member failure and system
result, actual capacity of an assembly can be higher than
effects which occur after first member failure as a result of residual
capacity at first member failure. capacity in the test assembly (see Section 7).
8.2.4 If increased performance is to be based on material
NOTE 4—Residual capacity theoretically reduces the probability that a
“weak-link” failure will propagate into progressive collapse of the property variability, the effects of the property variability shall
assembly. However, an initial failure under a gravity or similar type
be included in the analysis.
loading may precipitate dynamic effects resulting in instantaneous col-
8.2.4.1 For material properties which are assigned using
lapse.
global ingrade test data, the effects of the property variability,
7.1.2 Residual capacity does not reduce the probability of
including lot-by-lot variation, shall be accounted for through
failure of a single member. In fact, the increased number of
Monte Carlo simulation using validated property distributions
members in an assembly reduces the expected load at which
based on global ingrade test data (Practice D1990).
first member failure (FMF) will occur (see Note 5). For some
8.2.4.2 For material properties that are assigned using mill
specific assemblies, residual capacity from load sharing after
specific data, the effects of the property variability shall be
FMF may reduce the probability of progressive collapse or
accounted for using criteria upon which ongoing evaluation of
catastrophic failure of the assembly.
the material properties under consideration are based.
NOTE 5—Conventional engineering design criteria do not include
8.2.5 Extrapolation of results beyond the limitations as-
factors for residual capacity after FMF in the design of single structural
signed to the analysis of 8.2.1 is not permitted.
members. The increased probability of FMF with increased number of
members can be derived using probability theory and is not unique to
8.3 Empirical Method:
wood. The contribution of residual capacity should not be included in the
8.3.1 System effects in repetitive-member wood assemblies
development of system factors unless it can be combined with load
quantified using empirical test results shall be subject to the
sharing beyond FMF and assembly performance criteria which take into
following limitations:
account general structural integrity requirements such as avoidance of
progressive collapse (that is, increased safety factor, load factor, or
8.3.1.1 For qualification, a minimum of 28 assembly speci-
reliability index). Development of acceptable assembly criteria should
mens shall be tested for a reference condition. Additional
consider the desired reliability of the assembly.
samples containing 28 assembly specimens shall be tested for
7.2 Variables affecting Residual Capacity Effects on
additional loading and test conditions.
Strength include:
Exception:Whensystemfactorsarelimitedtoserviceability,
7.2.1 Loading conditions,
the number of assembly tests need not exceed that required to
7.2.2 Load sharing,
estimate the mean within 65 % with 75 % confidence.
7.2.3 Composite action,
NOTE7—Theminimumsamplesizeof28wasselectedfromTable2of
7.2.
...
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 − 03 (Reapproved 2008) D6555 − 03 (Reapproved 2014)
Standard Guide for
Evaluating System Effects in Repetitive-Member Wood
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.
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.
1.3 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 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D245 Practice for Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber
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 Aug. 1, 2008Aug. 1, 2014. Published August 2008August 2014. Originally approved in 2000. Last previous edition approved in 20032008 as
D6555 – 03.D6555 – 03 (2008). DOI: 10.1520/D6555-03R08.10.1520/D6555-03R14.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6555 − 03 (2014)
D1990 Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size
Specimens
D2915 Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based Products
D5055 Specification for Establishing and Monitoring Structural Capacities of Prefabricated Wood I-Joists
3. Terminology
3.1 Definitions:
3.1.1 composite action, n—interaction of two or more connected wood members that increases the effective section properties
over that determined for the individual members.
3.1.2 element, n—a discrete physical piece of a member such as a truss chord.
3.1.3 global correlation, n—correlation of member properties based on analysis of property data representative of the species
or species group for a large defined area or region rather than mill-by-mill or lot-by-lot data. The area represented may be defined
by political, ecological, or other boundaries.
3.1.4 load sharing, n—distribution of load among adjacent, parallel members in proportion to relative member stiffness.
3.1.5 member, n—a structural wood element or elements such as studs, joists, rafters, tresses, that carry load directly to assembly
supports. A member may consist of one element or multiple elements.
3.1.6 parallel framing system, n—a system of parallel framing members.
3.1.7 repetitive-member wood assembly, n—a system in which three or more members are joined using a transverse
load-distributing element.
3.1.7.1 Discussion—
Exception: Two-ply assemblies can be considered repetitive-member assemblies when the members are in direct side-by-side
contact and are joined together by mechanical connections or adhesives, or both, to distribute load.
3.1.8 residual capacity, n—ratio of the maximum assembly capacity to the assembly capacity at first failure of an individual
member or connection.
3.1.9 sheathing gaps, n—interruptions in the continuity of a load-distributing element such as joints in sheathing or decking.
3.1.10 transverse load-distributing elements, n—structural components such as sheathing, siding and decking that support and
distribute load to members. Other components such as cross bridging, solid blocking, distributed ceiling strapping, strongbacks,
and connection systems may also distribute load among members.
4. Significance and Use
4.1 This guide covers variables to be considered in the evaluation of the performance of repetitive-member wood assemblies.
System performance is attributable to one or more of the following effects:
4.1.1 Load sharing,
4.1.2 Composite action, or
4.1.3 Residual capacity.
4.2 This guide is intended for use where design stress adjustments for repetitive-member assemblies are being developed.
4.3 This guide serves as a basis to evaluate design stress adjustments developed using analytical or empirical procedures.
NOTE 1—Enhanced assembly performance due to intentional overdesign or the contribution of elements not considered in the design are beyond the
scope of this guide.
5. Load Sharing
5.1 Explanation of Load Sharing:
5.1.1 Load sharing reduces apparent stiffness variability of members within a given assembly. In general, member stiffness
variability results in a distribution of load that increases load on stiffer members and reduces load on more flexible members.
5.1.2 A positive strength-stiffness correlation for members results in load sharing increases, which give the appearance of higher
strength for minimum strength members in an assembly under uniform loads.
NOTE 2—Positive correlations between modulus of elasticity and strength are generally observed in samples of “mill run” dimension lumber; however,
no process is currently in place to ensure or improve the correlation of these relationships on a grade-by-grade or lot-by-lot basis. Where design values
for a member grade are based on global values, global correlations may be used with that grade when variability in the stiffness of production lots is taken
into account.
5.1.3 Load sharing tends to increase as member stiffness variability increases and as transverse load-distributing element
stiffness increases. Assembly capacity at first member failure is increased as member strength-stiffness correlation increases.
D6555 − 03 (2014)
NOTE 3—From a practical standpoint, the system performance due to load sharing is bounded by the minimum performance when the minimum
member in the assembly acts alone and by the maximum performance when all members in the assembly achieve average performance.
5.2 Variables affecting Load Sharing Effects on Stiffness include:
5.2.1 Loading conditions;
5.2.2 Member span, end conditions, and support conditions;
5.2.3 Member spacing;
5.2.4 Variability of member stiffness;
5.2.5 Ratio of average transverse load-distributing element stiffness to average member stiffness;
5.2.6 Sheathing gaps;
5.2.7 Number of members;
5.2.8 Load-distributing element end conditions;
5.2.9 Lateral bracing; and
5.2.10 Attachment between members.
5.3 Variables affecting Load Sharing Effects on Strength include:
5.3.1 Load sharing for stiffness (5.2), and
5.3.2 Level of member strength-stiffness correlation.
6. Composite Action
6.1 Explanation of Composite Action:
6.1.1 For bending members, composite action results in increased flexural rigidity by increasing the effective moment of inertia
of the combined cross-section. The increased flexural rigidity results in a redistribution of stresses which usually results in
increased strength.
6.1.2 Partial composite action is the result of a non-rigid connection between elements which allows interlayer slip under load.
6.1.3 Composite action decreases as the rigidity of the connection between the transverse load-distributing element and the
member decreases.
6.2 Variables affecting Composite Action Effects on Stiffness include:
6.2.1 Loading conditions,
6.2.2 Load magnitude,
6.2.3 Member span,
6.2.4 Member spacing,
6.2.5 Connection type and stiffness,
6.2.6 Sheathing gap stiffness and location in transverse load-distributing elements, and
6.2.7 Stiffness of members and transverse load-distributing elements (see 3.1.5).
6.3 Variables affecting Composite Action Effects on Strength include:
6.3.1 Composite action for stiffness (6.2), and
6.3.2 Location of sheathing gaps along members.
7. Residual Capacity of the Assembly
7.1 Explanation of Residual Capacity : Capacity:
7.1.1 Residual capacity is a function of load sharing and composite action which occur after first member failure. As a result,
actual capacity of an assembly can be higher than capacity at first member failure.
NOTE 4—Residual capacity theoretically reduces the probability that a “weak-link” failure will propagate into progressive collapse of the assembly.
However, an initial failure under a gravity or similar type loading may precipitate dynamic effects resulting in instantaneous collapse.
7.1.2 Residual capacity does not reduce the probability of failure of a single member. In fact, the increased number of members
in an assembly reduces the expected load at which first member failure (FMF) will occur (see Note 5). For some specific
assemblies, residual capacity from load sharing after FMF may reduce the probability of progressive collapse or catastrophic
failure of the assembly.
NOTE 5—Conventional engineering design criteria do not include factors for residual capacity after FMF in the design of single structural members.
The increased probability of FMF with increased number of members can be derived using probability theory and is not unique to wood. The contribution
of residual capacity should not be included in the development of system factors unless it can be combined with load sharing beyond FMF and assembly
performance criteria which take into account general structural integrity requirements such as avoidance of progressive collapse (that is, increased safety
factor, load factor, or reliability index). Development of acceptable assembly criteria should consider the desired reliability of the assembly.
7.2 Variables affecting Residual Capacity Effects on Strength include:
7.2.1 Loading conditions,
7.2.2 Load sharing,
7.2.3 Composite action,
7.2.4 Number and type of members,
D6555 − 03 (2014)
7.2.5 Member ductility (brittle versus ductile),
7.2.6 Connection system,
7.2.7 Contribution from structural or nonstructural elements not considered in design, and
7.2.8 Contribution from structural redundancy.
8. Quantifying Repetitive-Member Effects
8.1 General—This section describes procedures for evaluating the system effects in repetitive-member wood assemblies using
either analytical or empirical methods. Analysis of the results for either method shall follow the requirements of 8.4.
8.2 Analytical Method:
8.2.1 System effects in repetitive-member wood assemblies shall be quantified using methods of mechanics and statistics.
8.2.2 Each component of the system factor shall be considered.
8.2.3 Confirmation tests shall be conducted to verify adequacy of the derivation in 8.2.1 to compute force distributions. Tests
shall cover the range of conditions (that is, variables listed in 5.2, 5.3, 6.2, 6.3, and 7.2) anticipated in use. If it is not possible to
test the full range of conditions anticipated in use, the results of limited confirmation tests shall be so reported and the application
of such test results clearly limited to the range of conditions represented by the tests. Confirmation tests shall reflect the statistical
assumptions of 8.2.1.
NOTE 6—When analyzing the results of confirmation tests, the user is cautioned to differentiate between system effects in repetitive-member wood
assemblies that occur prior to first member failure and system effects which occur after first member failure as a result of residual capacity in the test
assembly (see Section 7).
8.2.4 If increased performance is to be based on material property variability, the effects of the property variability shall be
included in the analysis.
8.2.4.1 For material properties which are assigned using global ingrade test data, the effects of the property variability, including
lot-by-lot variation, shall be accounted for through Monte Carlo simulation using validated property distributions based on global
ingrade test data (Practice D1990).
8.2.4.2 For material properties that are assigned using mill specific data, the effects of the property variability shall be accounted
for using criteria upon which ongoing evalua
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.