ASTM D6570-00a

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Designation:D6570–00a
Standard Practice for
Assigning Allowable Properties for Mechanically-Graded
Lumber
This standard is issued under the fixed designation D 6570; 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.
1. Scope D 4761 Test Method for Mechanical Properties of Lumber
and Wood-Based Structural Material
1.1 This practice provides for the methodology of grade
2.2 ANSI Standards:
qualification, assignment of design properties, and require-
ANSI/AITCA190.1, AmericanNationalStandardforWood
ments for the quality control of mechanically graded solid
Products—Structural Glued Laminated Timber
sawn lumber.
ANSI/AF&PA NDS, National Design Specification for
1.2 This practice acknowledges alternative methods for the
Wood Construction
assignment of specific properties. These methods are assign-
2.3 Canadian Standards Association Standard:
ment by test, relationship to other properties, and by proce-
CSA O141, Softwood Lumber
dures in other appropriate standards.
2.4 National Institute of Standards and Technology Stan-
2. Referenced Documents
dard:
Voluntary Product Standard PS 20, American Softwood
2.1 ASTM Standards:
Lumber Standard
D 9 Terminology Relating to Wood
D 143 Method of Testing Small Clear Specimens of Tim-
3. Terminology
ber
3.1 Definitions—For definitions of terms related to wood,
D 198 Test Methods of Static Tests of Lumber in Structural
refer to Terminology D 9.
Sizes
3.2 Definitions of Terms Specific to This Standard:
D 245 Practice for Establishing Structural Grades and Re-
3.2.1 mechanical evaluation, n—identification and ap-
lated Allowable Properties for Visually-Graded Lumber
praisal of one or more physical or mechanical lumber charac-
D 1165 Nomenclature of Domestic Hardwoods and Soft-
teristics as part of the lumber segregation process.
woods
3.2.2 mechanically-graded lumber, n—solid sawn lumber
D 1990 Practice for Establishing Allowable Properties for
graded by mechanical evaluation. Visual evaluation also may
Visually-Graded Dimension Lumber from In-Grade Tests
2 be required. The material has assigned design properties and is
of Full-Size Specimens
manufactured for use as structural members.
D 2395 Test Methods for Specific Gravity of Wood and
2 3.2.3 qualified agency, n—an organization, hereafter re-
Wood-Based Materials
ferred to as the agency, that has trained personnel and proce-
D 2555 Test Methods for Establishing Clear Wood Strength
2 dures to ensure the system evaluations and grades comply with
Values
all applicable requirements of this practice.
D 2915 Practice for Evaluating Allowable Properties for
2 3.2.3.1 Discussion—The agency shall have no financial
Grades of Structural Lumber
interest in, nor shall be financially dependent upon, any single
D 3737 Practice for Establishing Stresses for Structural
2 company manufacturing the product being inspected or tested;
Glued Laminated Timber (Glulam)
and shall not be owned, operated, or controlled by any such
D 4442 TestMethodsforDirectMoistureContentMeasure-
company.
ment of Wood and Wood-Based Materials
3.2.3.2 Discussion—The agency shall conform with the
D 4444 TestMethodsforUseandCalibrationofHand-Held
provisions for agency accreditation under the appropriate
Moisture Meters
consensus standard.
1 3
This practice is under the jurisdiction ofASTM Committee D07 on Wood and Available from the American National Standards Institute, 1430 Broadway,
is the direct responsibility of Subcommittee D07.02 on Lumber and Engineered New York, NY 10018.
Wood Products. Available from the National Institute of Standards and Technology, U.S.
Current edition approved Oct. 10, 2000. Published December 2000. Originally Department of Commerce, Washington, DC 20234.
published as D 6570-00. Last previous edition D 6570-00. Available from Canadian StandardsAssociation, 178 Rexdale, Ontario, Canada
Annual Book of ASTM Standards, Vol 04.10. M9W IR3.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6570
3.2.4 visual evaluation, n—identification and appraisal of 6.3.1 When mechanical and physical properties in Section 7
lumber growth and manufacturing characteristics by visual are determined by tests, the appropriateASTM standards shall
means as part of the lumber segregation process. be used.
6.3.2 Mechanical test methods shall be in accordance with
NOTE 1—In the United States and Canada, criteria for agency accredi-
either Test Method D 198 or Test Methods D 4761.
tation are contained in PS-20, ANSI/AITC A190, and CSA O141.
6.3.2.1 The determination of the MOE and MOR by edge-
4. Significance and Use wise bending shall employ third-point in accordance with Test
Methods D 4761.
4.1 Theproceduresdescribedinthispracticeareintendedto
6.3.2.2 The determination of the MOE by flat-wise bending
be used to establish appropriate allowable unit stresses, moduli
shall be in accordance with Test Methods D 4761.
of elasticity, and specific gravity for mechanically graded solid
6.3.2.3 The UTS of a sample shall be determined according
sawn lumber. An on-going quality control program to monitor
to Test Methods D 4761. Whenever possible, a minimum
compliance with the assigned grade properties is required.
gauge length of not less than 96-in. (2.44 m) shall be used.
WhendeterminationofthetensionparalleltothegrainMOEis
5. System Requirements
desired, testing shall be conducted according to the provisions
5.1 Mechanical Device Requirements—A mechanical de-
of Test Method D 198.
vice used as part of the grading process shall demonstrate the
6.3.3 Specific gravity shall be based on weight and dimen-
ability to measure the mechanical or physical wood property
sions when oven-dry as specified in Test Methods D 2395.
used to segregate the lumber.
Measurements shall either be taken on oven-dried specimens,
5.2 Visual Requirements:
oratsomeothermoisturecontentandthevaluesadjustedtothe
5.2.1 Characteristicstobelimitedbyvisualevaluation,shall
oven-dry condition.
be documented as part of the qualification and quality control
6.3.4 Determination of the moisture content of the lumber
procedures. Such limitations shall be part of the grade require-
sample shall be in accordance with Test Methods D 4442 or
ments.
D 4444.
5.2.2 Personnel conducting visual evaluations shall be
qualified by the agency.
7. Procedures for Assignment of Allowable Mechanical
Properties and Specific Gravity
6. Criteria for Grade Qualification
7.1 Allowable mechanical properties and specific gravity
6.1 General Requirements: shall be assigned using the qualification test procedures of 7.2,
6.1.1 A minimum of one assigned property of a grade shall the property correlation procedures of 7.3, or the procedures of
be qualified by test. The grade assignment for properties 7.4.These alternative procedures of 7.2, 7.3, and 7.4 define the
qualified by test is given in 7.2. maximum property values, which are permitted to be assigned
6.1.1.1 If the modulus of elasticity (MOE) is the only to a grade of mechanically-graded lumber.
property assigned to a grade, it shall be evaluated by test. 7.1.1 Selection of the procedures specified in 7.1 to estab-
6.1.1.2 If both strength and MOE properties are assigned to lish a value for any particular property assigned to a grade is
a grade, a minimum of one strength property and one MOE the prerogative of the grade specification author.
property shall be evaluated by test. If only one strength 7.1.2 The factors used in 7.2 and 7.3 apply to softwood
property is tested, that property shall be either the modulus of lumber. Hardwood lumber species shall be reduced by the
rupture (MOR) or ultimate tensile stress (UTS). applicable factors in Practice D 245, Table 10.
6.1.2 Each grade shall be qualified at each size and for each 7.1.3 If the Fb is to be an assigned property, it shall be
species/species group.
determined by the test procedures of 7.2.
6.1.3 Sampling,evaluation,andpresentationofdatashallbe 7.2 Assignment of Allowable Properties by Qualification
in accordance with Practice D 2915.
Tests:
6.2 Qualification Samples: 7.2.1 Assignment of allowable properties by test shall
6.2.1 Thecriteriaforselectingqualificationsamplesshallbe
follow the procedures of this section. Test results shall be
documented and shall be in accordance with 6.1.3. evaluated according to Practice D 2915.
6.2.2 Allqualificationsamplesshallmeetthevisualrequire- 7.2.1.1 Qualification tests are used to either establish allow-
ments established for the grade. able mechanical property values for new grades or to qualify
6.2.3 The minimum sample size for estimation of strength for published grade categories.
properties, and MOE shall be 53 specimens. 7.2.2 Extreme Fiber Stress in Bending (Fb)—The fifth
6.2.4 The minimum sample size for estimation of mean or percentile tolerance limit (75 % confidence) for the MOR of
median property values, other than MOE, shall be 30 speci- the qualification sample shall equal or exceed 2.1 times the
mens. assigned Fb value.
6.2.5 When the allowable shear stress parallel to grain (Fv) 7.2.3 Fiber Stress in Tension Parallel to Grain (Ft)—The
or the allowable compressive stress perpendicular to grain fifth percentile tolerance limit (75 % confidence) for the UTS
(Fc') are determined in accordance with 7.3.4 and 7.3.5 of the qualification sample shall equal or exceed 2.1 times the
respectively, the specific gravity of a minimum of 30 qualifi- assigned Ft value.
cation test specimens shall be measured and recorded. 7.2.4 Fiber Stress in Compression Parallel to Grain (Fc)—
6.3 Qualification Test Methods: The fifth percentile tolerance limit (75 % confidence) for
D6570
ultimate compressive strength parallel to grain (UCS) of the procedures of Practice D 245 for visually-graded solid sawn
qualification sample shall equal or exceed 1.9 times the lumber of the same species or species group.
assigned Fc value. 7.4.4 Specific Gravity—The specific gravity shall be as-
7.2.5 Shear Stress Parallel to Grain (Fv)—Thefifthpercen- signed as reported inANSI/AF&PA- NDS for visually-graded
tile tolerance limit (75 % confidence) Fv for the qualification solid sawn lumber of the same species or species group.
sample shall equal or exceed 2.1 times the assigned Fv value.
8. Minimum Allowable Property Increment
7.2.6 Modulus of Elasticity—The upper 95 % confidence
interval of the qualification sample mean MOE shall equal or
8.1 Allowable properties shall be rounded in accordance
exceed, the assigned grade MOE.
with Table 1.
7.2.7 Specific Gravity (SG)—The upper 95 % confidence
interval of the qualification sample mean specific gravity shall 9. Quality Control
equal or exceed the assigned specific gravity value.
9.1 A quality control program shall be developed for each
7.3 Assignment of Allowable Properties Based on Relation-
mechanical grading system. The quality control program shall
ships:
delineate the respective responsibilities of the producer and the
7.3.1 The methods of 7.3 permit assignment of certain
agency.
allowable properties based on recognized relationships be-
9.2 The quality control program shall include monitoring
tween the assigned properties. This assignment shall be in
and control of both the mechanical and visual portions of the
accordance with the following procedures.
system.
7.3.2 Fiber Stress in Tension Parallel to Grain:
9.2.1 The visual evaluation of the grade shall be conducted
7.3.2.1 The maximum allowable Ft shall be assigned in
in accordance with the applicable agency requirements.
accordance with an established grade assignment model based
9.2.2 The quality control program shall address the proce-
on the assigned Fb which has been published by the agency.
dures for quality control of the mechanical system.
7.3.2.2 In the absence of corroborative data, a maximum
9.3 The quality control program shall require periodic
Ft/Fb ratio of 0.45 shall be used.
evaluation of at least one of the assigned properties qualified in
7.3.3 Fiber Stress in Compression Parallel to Grain:
6.1.1.
7.3.3.1 ThemaximumallowableFcshallbecalculatedfrom
9.4 A quality manual shall be prepared for each production
the following equation:
facility.
Fc5~0.7098Fb12060.7!/1.9 (1) 9.4.1 The quality manual shall address precision and bias of
calibration and measurement.
where:
9.4.2 The manual shall describe the inspection, sampling,
Fb = the assigned Fb for the grade.
testing, and analysis to be conducted in accordance with this
7.3.4 Shear Parallel to Grain—The Fv determined by a
practice and other applicable requirements.
specific gravity based model (see Appendix X1) is permitted
9.4.3 The manual shall describe corrective action to be
when the specific gravity is assigned in accordance with 7.2.7
taken with nonconforming material.
or 7.3.6.
9.4.4 Documentation requirements of the quality control
7.3.5 Fiber Stress in Compression Perpendicular to Grain
program shall be described in the manual, including retention
' '
(Fc )—The Fc determined by a specific gravity based model
and other applicable requirements.
(see Appendix X1) is permitted when specific gravity is
9.4.5 The manual shall describe the individual and joint
assigned in accordance with 7.2.7 or 7.3.6.
responsibilities of the production facility and the agency.
7.3.6 Specific Gravity—It is permitted to assign specific
gravity in accordance with a model that relates grading
10. Keywords
machine measurement to specific gravity. When such a model
10.1 lumber; mechanically-graded lumber; solid sawn lum-
is used, the agency shall develop corroborative data to support
ber; wood
the appropriateness of the assigned specific gravity.
7.4 AssignmentofAllowablePropertiesbyOtherStandards:
7.4.1 The methods of 7.4 permit assignment of certain
TABLE 1 Rounding Rules for Allowable Property Values
allowable properties based on procedures in the appropriate
MOE 100 000 psi
ASTM and ANSI standards. Fb 50 psi at 1000 psi
and above
7.4.2 Shear Parallel to Grain Stress—The Fv shall be
25 psi below 1000 psi
assigned in accordance with the procedures of Practice D 245
Ft 25 psi
for visually-graded solid sawn lumber of the same species or Fc 25 psi
Fc' 5 psi
species group.
Fv 5 psi
7.4.3 Fiber Stress in Compression Perpendicular to
SG 0.01
Grain—The Fc' shall be assigned in accordance with the
D6570
APPENDIXES
(Nonmandatory Information)
X1. FORMULAS FOR DETERMINING THE SHEAR STRESS PARALLEL TO GRAIN AND FIBER STRESS IN
COMPRESSION PERPENDICULAR TO GRAIN
X1.1 Shear
...