1、Designation: D 1990 00 (Reapproved 2002)e1Standard 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 ye
2、ar oforiginal adoption 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.e1NOTERef (14) was added in September 2002.INTRODUCTIONVisual str
3、ess-grades of lumber manufactured in North America have evolved 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 of Test Methods D 2555.The clear wood va
4、lues 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 structurallumber as commercially produced and marketed has become possible with the development of suitabletest equipment that permi
5、ts rapid rates of loading to test large numbers of pieces from commerciallumber 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 evaluat
6、ing the data and assigning allowable propertiesto both tested and 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 assi
7、gning allowable stress and modulus ofelasticity values to dimension 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 procedu
8、res used in thispractice is that the samples selected and tested 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 ent
9、ire growth range ofa species or species group. Every effort shall be made to ensurethe representativeness of the test sample.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 modul
10、us ofelasticity values 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 Lumb
11、er PS20-70.NOTE 1In 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
12、This standard does 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 Docum
13、ents2.1 ASTM Standards:D9 Terminology Relating to Wood2D 198 Methods of Static Tests of Timbers in StructuralSizes2D 245 Practice for Establishing Structural Grades and Re-lated Allowable Properties for Visually Graded Lumber2D 1165 Nomenclature of Domestic Hardwoods and Soft-woods21This practice is
14、 under the jurisdiction of ASTM Committee D07 on Wood andis the direct responsibility of Subcommittee D7.02 on Lumber and EngineeredWood Products.Current edition approved April 10, 2000. Published June 2000. Originallypublished as D 1990 91. Last previous edition D 1990 97.2Annual Book of ASTM Stand
15、ards, Vol 04.10.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 2555 Test Methods for Establishing Clear-Wood StrengthValues2D 2915 Practice for Evaluating Allowable Properties forGrades of Structural Lumber2D 4442 Test Methods for
16、 Direct Moisture Content Measure-ment of Wood and Wood-Base Materials2D 4444 Test Methods for Use and Calibration of Hand-HeldMoisture Meters2D 4761 Test Methods for Mechanical Properties of Lumberand Wood-Base Structural Material2IEEE-SI 1032.2 American Softwood Lumber Standard:National Institute o
17、f Standards and Technology VoluntaryProduct Standard PS 20-9443. Terminology3.1 Definitions:3.1.1 For definitions of terms related to wood, refer toTerminology D9.3.2 Definitions of Terms Specific to This Standard:3.2.1 characteristic sizethe standard dimensions of thepiece at which the characterist
18、ic 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 % moisture content.3.2.2 characteristic valuethe population mean, median ortolerance limit value estimated
19、 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 development of allowable stressand modulus of elasticity values. Typically for structural visualgrades, standard
20、ized 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 data at the standardizedconditions, its appropriateness shall be demonstrated. (SeePractice D 2915 for
21、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 grades of major volume, commercially availableNorth American softwood species groups. For other species (
22、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 development of these procedureswere as described in the grading rules for Douglas Fir-Larch, Hem-Fir andSout
23、hern Pine from the United States, and Spruce-Pine-Fir, Douglasfir(N), and Hem-Fir(N) from Canada (1, 2, 3, and 4)5. The specific speciesgroupings, together with botanical names are given in NomenclatureD 1165.3.2.3 grade quality index (GQI)A numerical assessmentof the characteristics found in the sa
24、mple 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 modulus ofelasticity with respect to grade (Note 4).NOTE 4In the North American In-Grade test program, lum
25、ber 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 type of failure indicated bythe failure code (see Test Methods D 4761). Strength ratios were calcu-lated a
26、ccording 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 bending. Thesample grade quality index for each sample was calculated as thenonparametric five percentile p
27、oint 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 grades ascommercially produced. Samples collected in this manner areintended to represent the full range o
28、f 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 isintended to characterize the property trends for a range ofgrades for a single size or a range of sizes for
29、 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 characterize thatsampling unit.3.2.7 thicknessthe lesser dimension perpendicular to thelong axis of lumber.3.2.8
30、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 procedures described in this practice are intended tobe used to establish allowable stress and modulus of ela
31、sticityvalues 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 and grades exists. In addition, the methodology forestablishing allowable stress and modulus of elasticit
32、y 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.4.2 Methods for establishing allowable stress and modulusof elasticity values for a single size/grade t
33、est 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 representativeness ofthe input test data.4.3 A review and reassessment of values derived from thispractice shall be con
34、ducted 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 orre-evaluation, or both, in accordance with the procedures ofthis practice may be needed.3Annual Book of ASTM Standards, Vol 14.0
35、2.4Available from Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.5The boldface numbers in parentheses refer to the references listed at the end ofthis practice.D 1990 00 (2002)e125. Documentation of Results, Adjustments, andDevelopment of Allowable Properties5.1 Re
36、porting 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 des
37、cription 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 ofpro
38、perty 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 pract
39、ice and 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 ar
40、chive 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
41、errors. 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.Cl
42、ass widths 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 documen
43、ted in 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
44、.4 Provide 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 present
45、ed to 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 brie
46、f summary 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 m
47、aterial 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 syst
48、emshould 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 Practice D 245 (seeRefs 1, 2, 3,
49、 and 4).7. Minimum Sampling Matrix7.1 General ConsiderationsDevelopment of allowablestress and modulus of elasticity values under this practice maybe for either a single size (7.3) or a single grade (7.2) or a fullmatrix of sizes and grades (7.4). The required sampling matrixis determined by the desired end result. The intent of a samplematrix is to provide sufficient data across the sizes or grades, orboth, to permit interpolation between data points. Extrapolationbeyond the sample matrix may be misleading and therefore isnot recommended. Assignment of allow
