ASTM D1990-00(2002)e1
(Practice)Standard Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size Specimens
Standard Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size Specimens
SIGNIFICANCE AND USE
The procedures described in this practice are intended to be used to establish allowable stress and modulus of elasticity values for solid sawn, visually graded dimension lumber from In-Grade type test data. These procedures apply to the tested and untested sizes and grades when an adequate data matrix of sizes and grades exists. In addition, the methodology for establishing allowable stress and modulus of elasticity values for combinations of species and species groups is covered. Allowable stress and modulus of elasticity values may also be developed for a single size or a single grade of lumber from test data.
Methods for establishing allowable stress and modulus of elasticity values for a single size/grade test cell are covered in Practice D 2915. The appropriateness of these methods to establish allowable stress and modulus of elasticity values is directly dependent upon the quality and representativeness of the input test data.
A review and reassessment of values derived from this practice shall be conducted if there is cause to believe that there has been a significant change in the raw material resource or product mix. If a change is found to be significant, retesting or re-evaluation, or both, in accordance with the procedures of this practice may be needed.
SCOPE
1.1 Due to the number of specimens involved and the number of mechanical properties to be evaluated, a methodology for evaluating the data and assigning allowable properties to both tested and untested grade/size cells is necessary. Sampling and analysis of tested cells are covered in Practice D 2915. The mechanical test methods are covered in Test Methods D 198 and D 4761. This practice covers the necessary procedures for assigning allowable stress and modulus of elasticity values to dimension lumber from In-Grade tests. The practice includes methods to permit assignment of allowable stress and modulus of elasticity values to untested sizes and grades, as well as some untested properties.
1.2 A basic assumption of the procedures used in this practice is that the samples selected and tested are representative of the entire global population being evaluated. This approach is consistent with the historical clear wood methodology of assigning an allowable property to visually-graded lumber which was representative of the entire growth range of a species or species group. Every effort shall be made to ensure the representativeness of the test sample.
1.3 This practice covers the principles and procedures for establishing allowable stress values for bending, tension parallel to grain, compression parallel to grain and modulus of elasticity values for structural design from "In-Grade" tests of full-size visually graded solid sawn dimension lumber. This practice is focused on, but is not limited to, grades which used the concepts incorporated in Practice D 245 and were developed and interpreted under American Softwood Lumber PS 20-70.
Note 1—In the implementation of the North American In-Grade test program, allowable stress values for compression perpendicular to grain and shear parallel to grain for structural design were calculated using the procedures of Practice D 245.
1.4 This practice only covers dimension lumber.
1.5 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.
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e1
Designation: D 1990 – 00 (Reapproved 2002)
Standard Practice for
Establishing Allowable Properties for Visually-Graded
Dimension Lumber from In-Grade Tests of Full-Size
Specimens
This standard is issued under the fixed designation D1990; 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 (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Ref (14) was added in September 2002.
INTRODUCTION
Visual stress-grades of lumber manufactured in North America have evolved from the procedures
ofPracticeD245.Allowablestressandmodulusofelasticityvaluesweredeterminedforthesegrades
usingtheproceduresofPracticeD245andtheappropriateclearwoodvaluesofTestMethodsD2555.
The clear wood values of Test Methods D2555 were developed from tests of small clear specimens.
Development of allowable stress and modulus of elasticity values from tests of full-size structural
lumberascommerciallyproducedandmarketedhasbecomepossiblewiththedevelopmentofsuitable
test equipment that permits rapid rates of loading to test large numbers of pieces from commercial
lumber production. These tests can be carried out at the production sites or in a laboratory.
1. Scope allel to grain, compression parallel to grain and modulus of
elasticity values for structural design from “In-Grade” tests of
1.1 Due to the number of specimens involved and the
full-size visually graded solid sawn dimension lumber. This
number of mechanical properties to be evaluated, a methodol-
practice is focused on, but is not limited to, grades which used
ogy for evaluating the data and assigning allowable properties
the concepts incorporated in Practice D245 and were devel-
to both tested and untested grade/size cells is necessary.
oped and interpreted under American Softwood Lumber PS
Sampling and analysis of tested cells are covered in Practice
20-70.
D2915. The mechanical test methods are covered in Test
MethodsD198andD4761.Thispracticecoversthenecessary
NOTE 1—In the implementation of the North American In-Grade test
procedures for assigning allowable stress and modulus of program, allowable stress values for compression perpendicular to grain
and shear parallel to grain for structural design were calculated using the
elasticity values to dimension lumber from In-Grade tests.The
procedures of Practice D245.
practice includes methods to permit assignment of allowable
stress and modulus of elasticity values to untested sizes and
1.4 This practice only covers dimension lumber.
grades, as well as some untested properties.
1.5 This standard does not purport to address all of the
1.2 A basic assumption of the procedures used in this
safety concerns, if any, associated with its use. It is the
practice is that the samples selected and tested are representa-
responsibility of the user of this standard to establish appro-
tive of the entire global population being evaluated. This
priate safety and health practices and determine the applica-
approach is consistent with the historical clear wood method-
bility of regulatory limitations prior to use.
ology of assigning an allowable property to visually-graded
2. Referenced Documents
lumber which was representative of the entire growth range of
aspeciesorspeciesgroup.Everyeffortshallbemadetoensure
2.1 ASTM Standards:
the representativeness of the test sample.
D9 Terminology Relating to Wood
1.3 This practice covers the principles and procedures for D198 Methods of Static Tests of Timbers in Structural
establishing allowable stress values for bending, tension par-
Sizes
D245 Practice for Establishing Structural Grades and Re-
lated Allowable Properties for Visually Graded Lumber
D1165 Nomenclature of Domestic Hardwoods and Soft-
This practice is under the jurisdiction ofASTM Committee D07 on Wood and
woods
is the direct responsibility of Subcommittee D7.02 on Lumber and Engineered
Wood Products.
Current edition approved April 10, 2000. Published June 2000. Originally
published as D1990–91. Last previous edition D1990–97.
Annual Book of ASTM Standards, Vol 04.10.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D 1990 – 00 (2002)
D2555 TestMethodsforEstablishingClear-WoodStrength parameter which allows modeling of strength and modulus of
Values elasticity with respect to grade (Note 4).
D2915 Practice for Evaluating Allowable Properties for
NOTE 4—In the North American In-Grade test program, lumber pro-
Grades of Structural Lumber
duced in accordance with visual stress grading rules developed from the
D4442 TestMethodsforDirectMoistureContentMeasure-
procedures of Practice D245 was sampled. For each test specimen a
ment of Wood and Wood-Base Materials
strength ratio was calculated for the particular type of failure indicated by
D4444 TestMethodsforUseandCalibrationofHand-Held the failure code (see Test Methods D4761). Strength ratios were calcu-
lated according to the formulas given in the appendix of Practice D245
Moisture Meters
for bending and compression parallel to grain test specimens. Strength
D4761 Test Methods for Mechanical Properties of Lumber
ratios for lumber tested in tension were calculated as for bending. The
and Wood-Base Structural Material
sample grade quality index for each sample was calculated as the
IEEE-SI 10
nonparametric five percentile point estimate of the distribution of strength
2.2 American Softwood Lumber Standard:
ratios. Specimens which failed in clear wood were excluded from the
National Institute of Standards and Technology Voluntary
sample for determining the sample GQI.
Product Standard PS 20-94
3.2.4 In-Grade—samples collected from lumber grades as
commercially produced. Samples collected in this manner are
3. Terminology
intended to represent the full range of strength and modulus of
3.1 Definitions:
elasticity values normally found within a grade.
3.1.1 For definitions of terms related to wood, refer to
3.2.5 sampling matrix—the collective designation used to
TerminologyD9.
describe all of the individual test cells. The sampling matrix is
3.2 Definitions of Terms Specific to This Standard:
intended to characterize the property trends for a range of
3.2.1 characteristic size—the standard dimensions of the
grades for a single size or a range of sizes for a single grade or
piece at which the characteristic value is calculated (Note 2).
a combination of both sizes and grades for a species or species
NOTE 2—In the North American In-Grade program, the characteristic
group.
size used was 1.5 in. (38 mm) thick by 7.25 in. (184 mm) wide by 144 in.
3.2.6 test cell—the combined test data for a single size/
(3.658 m) in length at 15% moisture content.
grade/species/property which is intended to characterize that
3.2.2 characteristic value—the population mean, median or
sampling unit.
tolerance limit value estimated from the test data after it has
3.2.7 thickness—the lesser dimension perpendicular to the
been adjusted to standardized conditions of temperature, mois-
long axis of lumber.
ture content and characteristic size. The characteristic value is
3.2.8 tolerance limit (TL)—referstothetolerancelimitwith
an intermediate value in the development of allowable stress
95% content and 75% confidence.
andmodulusofelasticityvalues.Typicallyforstructuralvisual
3.2.9 width—the greater dimension perpendicular to the
grades, standardized conditions are 73°F (23°C), and 15%
long axis of lumber.
moisture content (Note 3). A nonparametric estimate of the
characteristic value is the preferred estimate. If a distributional
4. Significance and Use
form is used to characterize the data at the standardized
conditions, its appropriateness shall be demonstrated. (See
4.1 Theproceduresdescribedinthispracticeareintendedto
Practice D2915 for guidance on selection of distribution.)
be used to establish allowable stress and modulus of elasticity
values for solid sawn, visually graded dimension lumber from
NOTE 3—The described adjustment factors and allowable stress and
In-Grade type test data. These procedures apply to the tested
modulus of elasticity value assignment procedures were developed based
and untested sizes and grades when an adequate data matrix of
on test data of visual grades of major volume, commercially available
NorthAmerican softwood species groups. For other species (see Nomen- sizes and grades exists. In addition, the methodology for
clature D1165) and for other grading methods, it may be necessary to
establishing allowable stress and modulus of elasticity values
verify that the listed adjustments are applicable. The commercial species
for combinations of species and species groups is covered.
groups and grading criteria used in the development of these procedures
Allowable stress and modulus of elasticity values may also be
wereasdescribedinthegradingrulesforDouglasFir-Larch,Hem-Firand
developedforasinglesizeorasinglegradeoflumberfromtest
Southern Pine from the United States, and Spruce-Pine-Fir, Douglas
data.
fir(N),andHem-Fir(N)fromCanada(1,2,3,and4) .Thespecificspecies
groupings, together with botanical names are given in Nomenclature
4.2 Methods for establishing allowable stress and modulus
D1165.
of elasticity values for a single size/grade test cell are covered
in Practice D2915. The appropriateness of these methods to
3.2.3 grade quality index (GQI)—A numerical assessment
establish allowable stress and modulus of elasticity values is
of the characteristics found in the sample specimens which are
directly dependent upon the quality and representativeness of
considered to be related to strength and are limited as part of
the input test data.
the grade description. The grade quality index is a scaling
4.3 A review and reassessment of values derived from this
practiceshallbeconductedifthereiscausetobelievethatthere
Annual Book of ASTM Standards, Vol 14.02.
has been a significant change in the raw material resource or
Available from Superintendent of Documents, U.S. Government Printing
product mix. If a change is found to be significant, retesting or
Office, Washington, DC 20402.
re-evaluation, or both, in accordance with the procedures of
The boldface numbers in parentheses refer to the references listed at the end of
this practice. this practice may be needed.
e1
D 1990 – 00 (2002)
5. Documentation of Results, Adjustments, and 5.5 Summary/Index—Prepare a brief summary of the pre-
Development of Allowable Properties sentation that highlights each of the major steps. An index or
tableofcontentsshallaccompanythedocumentthatreferences
5.1 Reporting Test Data:
the content and the corresponding paragraphs of this practice.
5.1.1 Summarizing Statistics:
5.1.1.1 Provide a set of summarizing statistics that includes
6. Development of Stress Grades
sample size, mean, median, standard deviation, confidence
6.1 Stress grades for lumber are designed to separate the
intervals, and nonparametric point estimates and tolerance
limits. If parametric methods are used to characterize the data, raw material source into marketable groups of specific quality
levels to which allowable stress and modulus of elasticity
provide a description of selection procedures and a tabulation
of distribution parameters. Document any “best fit” judgments values can be assigned. Stress grading systems used with this
practice shall be internally consistent and continuous (Note 6).
made in the selection of a distribution.
5.1.1.2 Provide a description of all statistical methods used
NOTE 6—To be considered internally consistent, a grading system
with the summarizing statistics.
should not be based on two or more methods of determining an allowable
5.1.2 Unadjusted Test Results—To permit verification of
property.Acontinuous system should not skip levels of material strength.
property calculations by regulatory and third party reviewers, For example, the North American In-Grade test program sampled grades
whichweredevelopedusingthestressratiosystemofPracticeD245(see
unadjustedindividualspecimentestresultsshallbemaintained
Refs 1, 2, 3, and 4).
insuitableachivalform.Thearchivedrecordsshallberetained
as long as the derived property values are applicable.Archived
7. Minimum Sampling Matrix
records shall be retained by the user of this practice and an
7.1 General Considerations—Development of allowable
independent public institution.
stress and modulus of elasticity values under this practice may
NOTE 5—In the United States, the USDA Forest Products Laboratory,
be for either a single size (7.3) or a single grade (7.2) or a full
theAmericanLumberStandardsCommittee,andcollegesanduniversities
matrix of sizes and grades (7.4).The required sampling matrix
areconsideredsuitableindependentpublicinstitutions.Itmaybedesirable
is determined by the desired end result. The intent of a sample
for historical or other purposes to continue to archive the records after the
matrixistoprovidesufficientdataacrossthesizesorgrades,or
derived values are no longer applicable. In such cases, the records should
both,topermitinterpolationbetweendatapoints.Extrapolation
be maintained by a public institution.
beyond the sample matrix may be misleading and therefore is
5.1.3 Significant Digits—With example calculations, illus-
not recommended. Assignment of allowable stress values
trate that adequate significant digits were maintained in inter-
beyondthesamplematrixispermittedwhenthereisadditional
mediate calculations to avoid round-off errors. Table 3 and
supporting information to indicate that the assigned values are
Section 4 of Practice E380 provide guidance.
conservative estimates.
5.2 Graphical Presentation—Graphical presentations are
7.2 Grade—To adequately model grade performance, it is
recommended to illustrate typical data sets. If parametric
necessarytosampleaminimumoftwogradesrepresentativeof
methods are used, histograms or cumulative distribution func-
the range of grade quality (Note 4). Grades sampled to model
tionsshallbeshownsuperimposedontheparametricfunctions.
grade relationships shall be separated by no more than one
Class widths shall meet the requirements of Practice D2915,
intermediary grade and no more than one quarter of the total
Table 7.
possible range (Note 7) in assumed bending GQI.
5.3 Preparation of Characteristic Values
NOTE 7—For the grading system sampled in the North American
5.3.1 Adjustments to Test Data:
In-Grade test program, the total possible range in strength ratio (GQI) is
5.3.1.1 Document each of the adjustments to the test data.
0 to 100%. The strength ratio concept is described in
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