1、Designation: D1990 14Standard Practice forEstablishing Allowable Properties for Visually-GradedDimension Lumber from In-Grade Tests of Full-SizeSpecimens1This standard is issued under the fixed designation D1990; the number immediately following the designation indicates the year oforiginal adoption
2、 or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONVisual stress-grades of lumber manufactured in North America have evolved fr
3、om the proceduresof Practice D245. Allowable stress and modulus of elasticity values were determined for these gradesusing the procedures of Practice D245 and the appropriate clear wood values of Practice D2555. Theclear wood values of Practice D2555 were developed from tests of small clear specimen
4、s.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 commerciallumb
5、er production. These tests can be carried out at the production sites or in a laboratory.1. Scope1.1 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 values for s
6、tructural design from “In-Grade” tests offull-size visually graded solid sawn dimension lumber. Thispractice also covers procedures for periodic monitoring, andadditional procedures, if needed, for evaluation and possiblereassessment of assigned design values. This practice is fo-cused on, but is no
7、t limited to, grades which used the conceptsincorporated in Practice D245 and were developed and inter-preted under American Softwood Lumber PS 20.1.2 A basic assumption of the procedures used in thispractice is that the samples selected and tested are representa-tive of the entire global population
8、 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 shall be made to ensurethe test sample is representative
9、 of population by grade andsize (see 7.1.1 and 7.1.2).1.3 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 and untested grade/size cells is necessary.Sampling and an
10、alysis of tested cells are covered in PracticeD2915. The mechanical test methods are covered in TestMethods D198 and D4761. This practice covers the necessaryprocedures for assigning allowable stress and modulus ofelasticity values to dimension lumber from In-Grade tests. Thepractice includes method
11、s to permit assignment of allowablestress and modulus of elasticity values to untested sizes andgrades, as well as some untested properties. The practiceincludes procedures for periodic monitoring of the species orspecies group to quantify potential changes in the product andverification of the assi
12、gned design values through, evaluation,and reassessment.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 D245.1.4 Thi
13、s practice only covers dimension lumber.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is the1This practice is under the jurisdiction of ASTM Committee D07 on Wood andis the direct responsibility of Subcommittee D07.02 on Lumber and Engin
14、eeredWood Products.Current edition approved Feb. 15, 2014. Published April 2014. Originallyapproved in 1991. Last previous edition approved in 2007 as D1990 07. DOI:10.1520/D1990-14.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1resp
15、onsibility 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 Standards:2D9 Terminology Relating to Wood and Wood-Based Prod-uctsD198 Test Methods of Static Tests o
16、f Lumber in StructuralSizesD245 Practice for Establishing Structural Grades and Re-lated Allowable Properties for Visually Graded LumberD1165 Nomenclature of Commercial Hardwoods and Soft-woodsD2555 Practice for Establishing Clear Wood Strength ValuesD2915 Practice for Sampling and Data-Analysis for
17、 Struc-tural Wood and Wood-Based ProductsD4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Base MaterialsD4444 Test Method for Laboratory Standardization andCalibration of Hand-Held Moisture MetersD4761 Test Methods for Mechanical Properties of Lumberand Wood-Base Structur
18、al MaterialE380 Practice for Use of the International System of Units(SI) (the Modernized Metric System) (Withdrawn 1997)3IEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System2.2 American Softwood Lumber Standard:National Institute of Standards and Techn
19、ology 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 characteristic value is calculate
20、d (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 from the test data a
21、fter it hasbeen adjusted to standardized conditions of temperature, mois-ture content and characteristic size.3.2.2.1 DiscussionThe characteristic value is an interme-diate value in the development of allowable stress and modulusof elasticity values. Typically for structural visual grades,standardiz
22、ed conditions are 73F (23C), and 15 % moisturecontent (Note 3).Anonparametric estimate of the characteristicvalue is the preferred estimate. If a distributional form is usedto characterize the data at the standardized conditions, itsappropriateness shall be demonstrated. (See Practice D2915 forguida
23、nce 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 (see N
24、omen-clature D1165) 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 andSouthern P
25、ine 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 NomenclatureD1165.3.2.3 grade quality index (GQI)A numerical assessmentof the characteristics found in the sample sp
26、ecimens 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, lumberprod
27、uced in accordance with visual stress grading rules (1, 2, 3, 4, 5, and6) developed from the procedures of Practice D245 was sampled. For eachtest specimen a strength ratio was calculated for the particular type offailure indicated by the failure code (see Test Methods D4761). Strengthratios were ca
28、lculated according to the formulas given in the appendix ofPractice D245 for bending and compression parallel to grain test speci-mens. Strength ratios for lumber tested in tension were calculated as forbending. The sample grade quality index for each sample was calculatedas the nonparametric five p
29、ercentile point estimate of the distribution ofstrength ratios. Specimens which failed in clear wood were excluded fromthe sample for determining the sample GQI.3.2.4 In-Gradesamples collected from lumber grades ascommercially produced.3.2.4.1 DiscussionSamples collected in this manner areintended t
30、o represent the full range of strength and modulus ofelasticity values normally found within a grade.3.2.5 monitoring, na periodic review of a subset ofstructural properties of a lumber cell to determine if a potentialdownward shift from the assigned values indicates a need foran evaluation or reass
31、essment, or both, of allowable propertiesdeveloped with this practice (Stage 1).3.2.6 evaluation, nThe process of examining data, includ-ing that collected over the course of a monitoring program thathas detected a shift in cell properties, to determine the likelycause for the detected shift in cell
32、 properties, developing thebest response to the data, and establishing that the actions aresufficient (Stage 2).3.2.6.1 DiscussionThe response to the evaluation caninclude altering the grade description, or the input resource, orchanging the method of processing. Testing is conducted toconfirm that
33、the action taken corrected the affected properties.2For referenced ASTM standards, visit the ASTM website, 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.3The last
34、approved version of this historical standard is referenced onwww.astm.org.4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.5The boldface numbers in parentheses refer to the references li
35、sted at the end ofthis practice.D1990 1423.2.7 reassessment, nThe recalculation of allowable prop-erties derived by this practice because of a change in productproperties (Stage 3).3.2.8 statistically significant downward shift, nA statisti-cally significant downward change in the monitored size gra
36、decell property in relation to a single cell from the matrix used toderive the current allowable property for which further actionis required in this Practice.3.2.8.1 DiscussionThe Wilcoxon nonparametric statisticaltest showing a change that is significant at the 0.05 level hasbeen selected as the c
37、onsensus statistical method for determin-ing when further action is required in this Standard.3.2.9 action levelThe lower property boundary, represent-ing a statistically significant downward shift, used in monitor-ing to define the property level at which additional confirma-tion testing during mon
38、itoring, or further action beyondmonitoring is necessary.3.2.10 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 a single grade
39、 ora combination of both sizes and grades for a species or speciesgroup.3.2.10.1 DiscussionThe sampling matrix is intended tocharacterize the property trends for a range of grades for asingle size or a range of sizes for a single grade or acombination of both sizes and grades for a species or specie
40、sgroup.3.2.11 test cellthe combined test data for a single size/grade/species/property which is intended to characterize thatsampling unit.3.2.12 thicknessthe lesser dimension perpendicular to thelong axis of lumber.3.2.13 tolerance limit (TL)refers to the tolerance limitwith 95 % content and 75 % c
41、onfidence.3.2.14 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 elasticityvalues for solid sawn, visually graded dimension lumber fromIn-Grade
42、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 elasticity valuesfor combinations of species and species groups is covered.Allowable
43、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 test cell are coveredin Practice D2915. The appropriateness of these methods
44、toestablish allowable stress and modulus of elasticity values isdirectly dependent upon the quality and representativeness ofthe input test data.4.3 A monitoring program shall be established to periodi-cally review the continued applicability of allowable propertiesderived by this practice. A monito
45、ring program will establishdata sets that are either the same as, above, or below the datathat was used to develop the current allowable properties.Upon detection of a statistically significant downward shift,evaluation of the data and confirmation of remedial actionsshall be undertaken. When evalua
46、tion is not undertaken or theresults of the evaluation indicate an adjustment to allowableproperties is appropriate, a reassessment shall be conducted tore-establish allowable properties.NOTE 5It is recognized that over time there is the potential forchanges in the raw material or product mix. In re
47、sponse to this amonitoring program must be conducted to ensure design values derived bythis practice are not invalidated by such changes. If the data collected witha monitoring provides evidence of an statistically significant downwardshift in lumber properties an evaluation program in accordance wi
48、th theprocedures of this practice is needed to detect and confirm that responsesto such changes are appropriate. Evaluation, if undertaken, provides ameans for responding to the data and assessing if the actions taken aresufficient. Following the confirmation of a statistically significant down-ward
49、 shift, reassessment of values shall be conducted if evaluation iseither not undertaken or does not adequately address the downward shift.5. Documentation of Results, Adjustments, andDevelopment of Allowable Properties5.1 Reporting 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 description of selection procedures and a
