ASTM D2915-17
(Practice)Standard Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based Products
Standard Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based Products
ABSTRACT
This practice covers sampling and analysis procedures for the investigation and evaluation of allowable properties of specified populations of stress-graded structural lumber. This practice generally assumes that the population is sufficiently large so that, for sampling purposes, it may be considered infinite. The population shall be clearly defined where it may be necessary to specify the following: (1) grade name and description, (2) geographical area over which sampling will take place, (3) species or species group, (4) time span for sampling (5) lumber size, and (6) moisture content. Two statistical techniques are described under this practice, namely: parametric and nonparametric analysis. The sampling methods include: (1) random sampling, (2) sampling with unequal probabilities, and (3) sequential sampling. Selection and method of determining sample size are detailed. The results of the tests performed shall be presented as (1) a set of summarizing statistics, and (2) an appendix of unadjusted individual test specimen results. The procedures and requirements for analysis of results are detailed and includes the following: (1) adjustment factors used to reduce the test statistics to the level of allowable properties, (2) formula for calculating apparent modulus of elasticity, sample mean, sample standard deviation, and confidence interval for the mean (3) sample nonparametric percent point estimate, (4) nonparametric lower tolerance limit, (5) parametric point estimate, (6) lower parametric tolerance limit, and (7) histogram and empirical cumulative distribution function. This practice does not specify the action to be taken after the results have been analyzed.
SCOPE
1.1 This practice covers sampling and analysis procedures for the investigation of specified populations of wood and wood-based structural products referred to in this standard as products. Appropriate product standards should be referenced for presentation requirements for data. Depending on the interest of the user, the population from which samples are taken may range from the products produced at a specific manufacturing site to all the products produced in a particular grade from a particular geographic area, during some specified interval of time. This practice generally assumes that the population is sufficiently large so that, for sampling purposes, it may be considered infinite. Where this assumption is inadequate, that is, the population is assumed finite, many of the provisions of this practice may be employed but the sampling and analysis procedure must be designed to reflect a finite population. The statistical techniques embodied in this practice provide procedures to summarize data so that logical judgments can be made. This practice does not specify the action to be taken after the results have been analyzed. The action to be taken depends on the particular requirements of the user of the product.
1.2 The values stated in inch-pound units are to be regarded as the standard.
1.3 This practice does not purport to address the adjustment factors needed to adjust test data to standardized mechanical and environmental conditions (that is, temperature, moisture, test span, or load duration). Additionally, it provides a basis for statistical estimates that will typically require further adjustment to determine design values for use with an accepted design methodology (that is, allowable stress, limit states, or load and resistance factor design). It shall be the responsibility of the user to seek out the appropriate adjustments in specific product standards.
1.4 This practice 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.
1.5 This international standard was developed in accordance with internation...
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Designation: D2915 − 17
Standard Practice for
Sampling and Data-Analysis for Structural Wood and Wood-
1
Based Products
This standard is issued under the fixed designation D2915; 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
Sampling and data analysis should be integrated in the design and evaluation of wood and
wood-basedstructuralproducts.Thispracticeisusefulinassessingtheappropriatenessoftheassigned
properties and for checking the effectiveness of grading procedures. Statistical methodologies are
providedtoserveasabasisfortheempiricalestablishmentandevaluationofmeanandnearminimum
property estimates.These population estimates are then used by product standards to assign structural
design values for use with an established design methodology (that is, allowable stress design, load
and resistance factor design, limit states design, etc.). Near-minimum property estimates are typically
used by the product standards to define the performance for a variety of structural properties where
strength is a primary consideration (that is, extreme fiber stress in bending, axial tension, axial
compression, shear, and elasticity for buckling concerns). Population mean estimates are often used
to assess serviceability design criteria where strength is not the primary design concern (that is,
elasticity estimates used for deformation calculations, permissible compression stress at a
deformation, etc.).
Forsituationswhereamanufacturedproductissampledrepeatedlyorlotsizesaresmall,alternative
2
test methods as described in Ref (1) may be more applicable.
1. Scope finite population. The statistical techniques embodied in this
practice provide procedures to summarize data so that logical
1.1 This practice covers sampling and analysis procedures
judgments can be made. This practice does not specify the
for the investigation of specified populations of wood and
action to be taken after the results have been analyzed. The
wood-based structural products referred to in this standard as
actiontobetakendependsontheparticularrequirementsofthe
products. Appropriate product standards should be referenced
user of the product.
for presentation requirements for data. Depending on the
interest of the user, the population from which samples are
1.2 Thevaluesstatedininch-poundunitsaretoberegarded
taken may range from the products produced at a specific
as the standard.
manufacturing site to all the products produced in a particular
1.3 This practice does not purport to address the adjustment
grade from a particular geographic area, during some specified
factors needed to adjust test data to standardized mechanical
interval of time. This practice generally assumes that the
and environmental conditions (that is, temperature, moisture,
population is sufficiently large so that, for sampling purposes,
it may be considered infinite. Where this assumption is testspan,orloadduration).Additionally,itprovidesabasisfor
inadequate, that is, the population is assumed finite, many of statistical estimates that will typically require further adjust-
the provisions of this practice may be employed but the
ment to determine design values for use with an accepted
sampling and analysis procedure must be designed to reflect a
design methodology (that is, allowable stress, limit states, or
load and resistance factor design). It shall be the responsibility
of the user to seek out the appropriate adjustments in specific
1
This practice is under the jurisdiction ofASTM Committee D07 on Wood and product standards.
is the direct responsibility of Subcommittee D07.02 on Lumber and Engineered
1.4 This practice does not purport to address all of the
Wood Products.
Current edition approved Oct. 1, 2017. Published October 2017. Originally
safety concerns, if any, associated with its use. It is the
approved in 1970 as D2915–70 T. Last previous edition approved in 2010 as
responsibility of the user of this standard to establish appro-
D2915–10. DOI: 10.1520/D2915-17.
2 priate safety and health practices and determine the applica-
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this practice. bility of regulatory limitations prior to use.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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D2915 − 17
1.5 This international standard was developed in accor- 3.2.5.1 Discussion—Structural design values are test results
dance with internationally recognized principles on standard- adjusted for duration of load, factor of safety, a
...
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: D2915 − 10 D2915 − 17
Standard Practice for
Sampling and Data-Analysis for Structural Wood and Wood-
1
Based Products
This standard is issued under the fixed designation D2915; 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
Sampling and data analysis should be integrated in the design and evaluation of wood and
wood-based structural products. This practice is useful in assessing the appropriateness of the assigned
properties and for checking the effectiveness of grading procedures. Statistical methodologies are
provided to serve as a basis for the empirical establishment and evaluation of mean and near minimum
property estimates. These population estimates are then used by product standards to assign structural
design values for use with an established design methodology (that is, allowable stress design, load
and resistance factor design, limit states design, etc.). Near-minimum property estimates are typically
used by the product standards to define the performance for a variety of structural properties where
strength is a primary consideration (that is, extreme fiber stress in bending, axial tension, axial
compression, shear, and elasticity for buckling concerns). Population mean estimates are often used
to assess serviceability design criteria where strength is not the primary design concern (that is,
elasticity estimates used for deformation calculations, permissible compression stress at a
deformation, etc.).
For situations where a manufactured product is sampled repeatedly or lot sizes are small, alternative
2
test methods as described in Ref (1) may be more applicable.
1. Scope
1.1 This practice covers sampling and analysis procedures for the investigation of specified populations of wood and
wood-based structural products referred to in this standard as products. Appropriate product standards should be referenced for
presentation requirements for data. Depending on the interest of the user, the population from which samples are taken may range
from the products produced at a specific manufacturing site to all the products produced in a particular grade from a particular
geographic area, during some specified interval of time. This practice generally assumes that the population is sufficiently large
so that, for sampling purposes, it may be considered infinite. Where this assumption is inadequate, that is, the population is
assumed finite, many of the provisions of this practice may be employed but the sampling and analysis procedure must be designed
to reflect a finite population. The statistical techniques embodied in this practice provide procedures to summarize data so that
logical judgments can be made. This practice does not specify the action to be taken after the results have been analyzed. The action
to be taken depends on the particular requirements of the user of the product.
1.2 The values stated in inch-pound units are to be regarded as the standard.
1.3 This practice does not purport to address the adjustment factors needed to adjust test data to standardized mechanical and
environmental conditions (that is, temperature, moisture, test span, or load duration). Additionally, it provides a basis for statistical
estimates that will typically require further adjustment to determine design values for use with an accepted design methodology
(that is, allowable stress, limit states, or load and resistance factor design). It shall be the responsibility of the user to seek out the
appropriate adjustments in specific product standards.
1.4 This practice 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.
1
This practice is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.02 on Lumber and Engineered Wood
Products.
Current edition approved Nov. 1, 2010Oct. 1, 2017. Published January 2011October 2017. Originally approved in 1970 as D2915 – 70 T. Last previous edition approved
in 20032010 as D2915 –03. –10. DOI: 10.1520/D2915-10.10.1520/D2915-17.
2
The boldface numbers in parentheses refer to the list of references at the end of thi
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