ASTM D1990-00e1

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: D 1990 – 00
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 D 1990; 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 (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Equation A1.1 was corrected editorially in October 2000.
INTRODUCTION
Visual stress-grades of lumber manufactured in North America have evolved from the procedures
of Practice D 245. Allowable stress and modulus of elasticity values were determined for these grades
using the procedures of Practice D 245 and the appropriate clear wood values of Test Methods D 2555.
The clear wood values of Test Methods D 2555 were developed from tests of small clear specimens.
Development of allowable stress and modulus of elasticity values from tests of full-size structural
lumber as commercially produced and marketed has become possible with the development of suitable
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 elasticity values for structural design from “In-Grade” tests of
full-size visually graded solid sawn dimension lumber. This
1.1 Due to the number of specimens involved and the
practice is focused on, but is not limited to, grades which used
number of mechanical properties to be evaluated, a methodol-
the concepts incorporated in Practice D 245 and were devel-
ogy for evaluating the data and assigning allowable properties
oped and interpreted under American Softwood Lumber PS
to both tested and untested grade/size cells is necessary.
20-70.
Sampling and analysis of tested cells are covered in Practice
D 2915. The mechanical test methods are covered in Test
NOTE 1—In the implementation of the North American In-Grade test
Methods D 198 and D 4761. This practice covers the necessary
program, allowable stress values for compression perpendicular to grain
and shear parallel to grain for structural design were calculated using the
procedures for assigning allowable stress and modulus of
procedures of Practice D 245.
elasticity values to dimension lumber from In-Grade tests. The
practice includes methods to permit assignment of allowable
1.4 This practice only covers dimension lumber.
stress and modulus of elasticity values to untested sizes and
1.5 This standard does not purport to address all of the
grades, as well as some untested properties.
safety concerns, if any, associated with its use. It is the
1.2 A basic assumption of the procedures used in this
responsibility of the user of this standard to establish appro-
practice is that the samples selected and tested are representa-
priate safety and health practices and determine the applica-
tive of the entire global population being evaluated. This
bility of regulatory limitations prior to use.
approach is consistent with the historical clear wood method-
2. Referenced Documents
ology of assigning an allowable property to visually-graded
lumber which was representative of the entire growth range of 2.1 ASTM Standards:
a species or species group. Every effort shall be made to ensure
D 9 Terminology Relating to Wood
the representativeness of the test sample. D 198 Methods of Static Tests of Timbers in Structural
1.3 This practice covers the principles and procedures for
Sizes
establishing allowable stress values for bending, tension par- D 245 Practice for Establishing Structural Grades and Re-
allel to grain, compression parallel to grain and modulus of lated Allowable Properties for Visually Graded Lumber
D 1165 Nomenclature of Domestic Hardwoods and Soft-
woods
This practice is under the jurisdiction of ASTM Committee D-7 on Wood and
is the direct responsibility of Subcommittee D7.02 on Lumber and Engineered
Wood Products.
Current edition approved Apr. 10, 2000. Published June 2000. Originally
published as D 1990 – 91. Last previous edition D 1990 – 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.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 1990
D 2555 Test Methods for Establishing Clear-Wood Strength parameter which allows modeling of strength and modulus of
Values elasticity with respect to grade (Note 4).
D 2915 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
D 4442 Test Methods for Direct Moisture Content Measure-
procedures of Practice D 245 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
D 4444 Test Methods for Use and Calibration of Hand-Held the failure code (see Test Methods D 4761). Strength ratios were calcu-
lated according to the formulas given in the appendix of Practice D 245
Moisture Meters
for bending and compression parallel to grain test specimens. Strength
D 4761 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
Terminology D 9.
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)—refers to the tolerance limit with
an intermediate value in the development of allowable stress
95 % content and 75 % confidence.
and modulus of elasticity values. Typically for structural visual
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 The procedures described in this practice are intended to
Practice D 2915 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
North American softwood species groups. For other species (see Nomen-
sizes and grades exists. In addition, the methodology for
clature D 1165) 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
were as described in the grading rules for Douglas Fir-Larch, Hem-Fir and
developed for a single size or a single grade of lumber from test
Southern Pine from the United States, and Spruce-Pine-Fir, Douglas
data.
fir(N), and Hem-Fir(N) from Canada (1, 2, 3, and 4) . The specific species
groupings, together with botanical names are given in Nomenclature
4.2 Methods for establishing allowable stress and modulus
D 1165.
of elasticity values for a single size/grade test cell are covered
in Practice D 2915. 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
practice shall be conducted if there is cause to believe that there
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.
5 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.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 1990
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
table of contents shall accompany the document that references
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
raw material source into marketable groups of specific quality
limits. If parametric methods are used to characterize the data,
levels to which allowable stress and modulus of elasticity
provide a description of selection procedures and a tabulation
values can be assigned. Stress grading systems used with this
of distribution parameters. Document any “best fit” judgments
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. A continuous system should not skip levels of material strength.
For example, the North American In-Grade test program sampled grades
property calculations by regulatory and third party reviewers,
which were developed using the stress ratio system of Practice D 245 (see
unadjusted individual specimen test results shall be maintained
Refs 1, 2, 3, and 4).
in suitable achival form. The archived records shall be retained
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
the American Lumber Standards Committee, and colleges and universities
matrix of sizes and grades (7.4). The required sampling matrix
are considered suitable independent public institutions. It may be desirable
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
matrix is to provide sufficient data across the sizes or grades, or
derived values are no longer applicable. In such cases, the records should
both, to permit interpolation between data points. 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-
beyond the sample matrix is permitted when there is additional
mediate calculations to avoid round-off errors. Table 3 and
supporting information to indicate that the assigned values are
Section 4 of Practice E 380 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
necessary to sample a minimum of two grades representative of
methods are used, histograms or cumulative distribution func-
the range of grade quality (Note 4). Grades sampled to model
tions shall be s
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