1、Designation: D 1990 07Standard Practice forEstablishing Allowable Properties for Visually-GradedDimension Lumber from In-Grade Tests of Full-SizeSpecimens1This standard is issued under the fixed designation D 1990; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONVisual stress-grades of lumber manufactured in North America have evolved
3、 from the proceduresof Practice D 245.Allowable stress and modulus of elasticity values were determined for these gradesusing the procedures of Practice D 245 and the appropriate clear wood values ofTest Methods D 2555.The clear wood values of Test Methods D 2555 were developed from tests of small c
4、lear specimens.Development of allowable stress and modulus of elasticity values from tests of full-size structurallumber as commercially produced and marketed has become possible with the development of suitabletest equipment that permits rapid rates of loading to test large numbers of pieces from c
5、ommerciallumber production. These tests can be carried out at the production sites or in a laboratory.1. Scope1.1 Due to the number of specimens involved and thenumber of mechanical properties to be evaluated, a methodol-ogy for evaluating the data and assigning allowable propertiesto both tested an
6、d untested grade/size cells is necessary.Sampling and analysis of tested cells are covered in PracticeD 2915. The mechanical test methods are covered in TestMethods D 198 and D 4761. This practice covers the necessaryprocedures for assigning allowable stress and modulus ofelasticity values to dimens
7、ion lumber from In-Grade tests. Thepractice includes methods to permit assignment of allowablestress and modulus of elasticity values to untested sizes andgrades, as well as some untested properties.1.2 A basic assumption of the procedures used in thispractice is that the samples selected and tested
8、 are representa-tive of the entire global population being evaluated. Thisapproach is consistent with the historical clear wood method-ology of assigning an allowable property to visually-gradedlumber which was representative of the entire growth range ofa species or species group. Every effort shal
9、l be made to ensurethe test sample is representative of population by grade andsize (see 7.1.1 and 7.1.2).1.3 This practice covers the principles and procedures forestablishing allowable stress values for bending, tension par-allel to grain, compression parallel to grain and modulus ofelasticity val
10、ues for structural design from “In-Grade” tests offull-size visually graded solid sawn dimension lumber. Thispractice is focused on, but is not limited to, grades which usedthe concepts incorporated in Practice D 245 and were devel-oped and interpreted under American Softwood Lumber PS20-70.NOTE 1In
11、 the implementation of the North American In-Grade testprogram, allowable stress values for compression perpendicular to grainand shear parallel to grain for structural design were calculated using theprocedures of Practice D 245.1.4 This practice only covers dimension lumber.1.5 This standard does
12、not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standa
13、rds:2D9 Terminology Relating to Wood and Wood-Based Prod-uctsD 198 Test Methods of Static Tests of Lumber in StructuralSizesD 245 Practice for Establishing Structural Grades and Re-lated Allowable Properties for Visually Graded Lumber1This practice is under the jurisdiction of ASTM Committee D07 on
14、Wood andis the direct responsibility of Subcommittee D07.02 on Lumber and EngineeredWood Products.Current edition approved Dec. 1, 2007. Published December 2007. Originallyapproved in 1991. Last previous edition approved in 2002 as D 1990 00 (2002)e1.2For referenced ASTM standards, visit the ASTM we
15、bsite, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United St
16、ates.Copyright by ASTM Intl (all rights reserved); Fri Jan 11 01:22:02 EST 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.D 1165 Nomenclature of Commercial Hardwoods and Soft-woodsD 2555 Practice for Establishing Clear Wood Strength Val-u
17、esD 2915 Practice for Evaluating Allowable Properties forGrades of Structural LumberD 4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Base MaterialsD 4444 Test Methods for Use and Calibration of Hand-HeldMoisture MetersD 4761 Test Methods for Mechanical Properties of Lumb
18、erand Wood-Base Structural MaterialIEEE-SI 1022.2 American Softwood Lumber Standard:National Institute of Standards and Technology VoluntaryProduct Standard PS 20-9433. Terminology3.1 Definitions:3.1.1 For definitions of terms related to wood, refer toTerminology D9.3.2 Definitions of Terms Specific
19、 to This Standard:3.2.1 characteristic sizethe standard dimensions of thepiece at which the characteristic value is calculated (Note 2).NOTE 2In the North American In-Grade program, the characteristicsize used was 1.5 in. (38 mm) thick by 7.25 in. (184 mm) wide by 144 in.(3.658 m) in length at 15 %
20、moisture content.3.2.2 characteristic valuethe population mean, median ortolerance limit value estimated from the test data after it hasbeen adjusted to standardized conditions of temperature, mois-ture content and characteristic size. The characteristic value isan intermediate value in the developm
21、ent of allowable stressand modulus of elasticity values. Typically for structural visualgrades, standardized conditions are 73F (23C), and 15 %moisture content (Note 3). A nonparametric estimate of thecharacteristic value is the preferred estimate. If a distributionalform is used to characterize the
22、 data at the standardizedconditions, its appropriateness shall be demonstrated. (SeePractice D 2915 for guidance on selection of distribution.)NOTE 3The described adjustment factors and allowable stress andmodulus of elasticity value assignment procedures were developed basedon test data of visual g
23、rades of major volume, commercially availableNorth American softwood species groups. For other species (see Nomen-clature D 1165) and for other grading methods, it may be necessary toverify that the listed adjustments are applicable. The commercial speciesgroups and grading criteria used in the deve
24、lopment of these procedureswere as described in the grading rules for Douglas Fir-Larch, Hem-Fir andSouthern Pine from the United States, and Spruce-Pine-Fir, Douglasfir(N), and Hem-Fir(N) from Canada (1, 2, 3, and 4)4. The specific speciesgroupings, together with botanical names are given in Nomenc
25、latureD 1165.3.2.3 grade quality index (GQI)A numerical assessmentof the characteristics found in the sample specimens which areconsidered to be related to strength and are limited as part ofthe grade description. The grade quality index is a scalingparameter which allows modeling of strength and mo
26、dulus ofelasticity with respect to grade (Note 4).NOTE 4In the North American In-Grade test program, lumber pro-duced in accordance with visual stress grading rules developed from theprocedures of Practice D 245 was sampled. For each test specimen astrength ratio was calculated for the particular ty
27、pe of failure indicated bythe failure code (see Test Methods D 4761). Strength ratios were calcu-lated according to the formulas given in the appendix of Practice D 245for bending and compression parallel to grain test specimens. Strengthratios for lumber tested in tension were calculated as for ben
28、ding. Thesample grade quality index for each sample was calculated as thenonparametric five percentile point estimate of the distribution of strengthratios. Specimens which failed in clear wood were excluded from thesample for determining the sample GQI.3.2.4 In-Gradesamples collected from lumber gr
29、ades ascommercially produced. Samples collected in this manner areintended to represent the full range of strength and modulus ofelasticity values normally found within a grade.3.2.5 sampling matrixthe collective designation used todescribe all of the individual test cells. The sampling matrix isint
30、ended to characterize the property trends for a range ofgrades for a single size or a range of sizes for a single grade ora combination of both sizes and grades for a species or speciesgroup.3.2.6 test cellthe combined test data for a single size/grade/species/property which is intended to character
31、ize thatsampling unit.3.2.7 thicknessthe lesser dimension perpendicular to thelong axis of lumber.3.2.8 tolerance limit (TL)refers to the tolerance limit with95 % content and 75 % confidence.3.2.9 widththe greater dimension perpendicular to thelong axis of lumber.4. Significance and Use4.1 The proce
32、dures described in this practice are intended tobe used to establish allowable stress and modulus of elasticityvalues for solid sawn, visually graded dimension lumber fromIn-Grade type test data. These procedures apply to the testedand untested sizes and grades when an adequate data matrix ofsizes a
33、nd grades exists. In addition, the methodology forestablishing allowable stress and modulus of elasticity valuesfor combinations of species and species groups is covered.Allowable stress and modulus of elasticity values may also bedeveloped for a single size or a single grade of lumber from testdata
34、.4.2 Methods for establishing allowable stress and modulusof elasticity values for a single size/grade test cell are coveredin Practice D 2915. The appropriateness of these methods toestablish allowable stress and modulus of elasticity values isdirectly dependent upon the quality and representativen
35、ess ofthe input test data.4.3 A review and reassessment of values derived from thispractice shall be conducted if there is cause to believe that therehas been a significant change in the raw material resource orproduct mix. If a change is found to be significant, retesting or3Available from U.S. Gov
36、ernment Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.4The boldface numbers in parentheses refer to the references listed at the end ofthis practice.D1990072Copyright by ASTM Intl (all rights reserved); Fri Jan 11 0
37、1:22:02 EST 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.re-evaluation, or both, in accordance with the procedures ofthis practice may be needed.5. Documentation of Results, Adjustments, andDevelopment of Allowable Properties5.1 Reporti
38、ng Test Data:5.1.1 Summarizing Statistics:5.1.1.1 Provide a set of summarizing statistics that includessample size, mean, median, standard deviation, confidenceintervals, and nonparametric point estimates and tolerancelimits. If parametric methods are used to characterize the data,provide a descript
39、ion of selection procedures and a tabulationof distribution parameters. Document any “best fit” judgmentsmade in the selection of a distribution.5.1.1.2 Provide a description of all statistical methods usedwith the summarizing statistics.5.1.2 Unadjusted Test ResultsTo permit verification ofproperty
40、 calculations by regulatory and third party reviewers,unadjusted individual specimen test results shall be maintainedin suitable achival form. The archived records shall be retainedas long as the derived property values are applicable.Archivedrecords shall be retained by the user of this practice an
41、d anindependent public institution.NOTE 5In the United States, the USDA Forest Products Laboratory,theAmerican Lumber Standards Committee, and colleges and universitiesare considered suitable independent public institutions. It may be desirablefor historical or other purposes to continue to archive
42、the records after thederived values are no longer applicable. In such cases, the records shouldbe maintained by a public institution.5.1.3 Significant DigitsWith example calculations, illus-trate that adequate significant digits were maintained in inter-mediate calculations to avoid round-off errors
43、. Table 3 andSection 4 of Practice E 380 provide guidance.5.2 Graphical PresentationGraphical presentations arerecommended to illustrate typical data sets. If parametricmethods are used, histograms or cumulative distribution func-tions shall be shown superimposed on the parametric functions.Class wi
44、dths shall meet the requirements of Practice D 2915,Table 7.5.3 Preparation of Characteristic Values5.3.1 Adjustments to Test Data:5.3.1.1 Document each of the adjustments to the test data.5.3.1.2 If the adjustments to the test data follow proceduresfound in other ASTM standards or are documented in
45、 othersources, reference these sources in a manner permitting thereader to recreate the use of these sources in the sameapplication. Indicate the limitations of application.5.3.1.3 In the presentation, explain adjustments made to thedata which cannot be referenced to acknowledged sources.5.3.1.4 Pro
46、vide examples of all adjustment procedures.5.4 Development of Allowable Properties:5.4.1 Explain each step of the development of allowableproperties with reference to the appropriate paragraph of thispractice.5.4.2 GroupingSummarize all grouping calculations intabular form and examples presented to
47、illustrate application oflimiting criteria.5.4.3 Allowable Property Adjustments Illustrate each ofthe adjustments for allowable properties for at least one of thesize/grade combinations presented. Present all adjustments intabular form. Examples may be presented.5.5 Summary/IndexPrepare a brief summ
48、ary of the pre-sentation that highlights each of the major steps. An index ortable of contents shall accompany the document that referencesthe content and the corresponding paragraphs of this practice.6. Development of Stress Grades6.1 Stress grades for lumber are designed to separate theraw materia
49、l source into marketable groups of specific qualitylevels to which allowable stress and modulus of elasticityvalues can be assigned. Stress grading systems used with thispractice shall be internally consistent and continuous (Note 6).NOTE 6To be considered internally consistent, a grading systemshould not be based on two or more methods of determining an allowableproperty. A continuous system should not skip levels of material strength.For example, the North American In-Grade test program sampled gradeswhich were developed using the stress ratio system of Pra
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