1、Designation: D6570 04 (Reapproved 2010)D6570 18Standard Practice forAssigning Allowable Properties for Mechanically GradedLumber1This standard is issued under the fixed designation D6570; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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.1. Scope1.1 This practice covers the methodology of grade qualification, assignment of design properties, and req
3、uirements for thequality control of mechanically graded solid sawn lumber.1.2 This practice acknowledges alternative methods for the assignment of specific properties. These methods are assignment bytest, relationship to other properties, and by procedures in other appropriate standards.1.3 This int
4、ernational standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Co
5、mmittee.2. Referenced Documents2.1 ASTM Standards:2D9 Terminology Relating to Wood and Wood-Based ProductsD143 Test Methods for Small Clear Specimens of TimberD198 Test Methods of Static Tests of Lumber in Structural SizesD245 Practice for Establishing Structural Grades and Related Allowable Propert
6、ies for Visually Graded LumberD1165 Nomenclature of Commercial Hardwoods and SoftwoodsD1990 Practice for EstablishingAllowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-SizeSpecimensD2395 Test Methods for Density and Specific Gravity (Relative Density) of Wood and W
7、ood-Based MaterialsD2555 Practice for Establishing Clear Wood Strength ValuesD2915 Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based ProductsD3737 Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)D4442 Test Methods for Direct Moist
8、ure Content Measurement of Wood and Wood-Based MaterialsD4444 Test Method for Laboratory Standardization and Calibration of Hand-Held Moisture MetersD4761 Test Methods for Mechanical Properties of Lumber and Wood-Base Structural MaterialD7438 Practice for Field Calibration and Application of Hand-He
9、ld Moisture Meters2.2 ANSI Standards:3ANSI/AITC A190.1 American National Standard for Wood ProductsStructural Glued Laminated TimberANSI/AF and shall not be owned, operated, or controlled by any such company.3.2.3.2 DiscussionThe agency shall conform with the provisions for agency accreditation unde
10、r the appropriate consensus standard.3.2.4 visual evaluation, nidentification and appraisal of lumber growth and manufacturing characteristics by visual means aspart of the lumber segregation process.NOTE 1In the United States and Canada, criteria for agency accreditation are contained in PS 20, ANS
11、I/AITC A190.1, and CSA O141.4. Significance and Use4.1 The procedures described in this practice are intended to be used to establish appropriate allowable unit stresses, moduli ofelasticity, and specific gravity for mechanically graded solid sawn lumber. An on-going quality control program to monit
12、orcompliance with the assigned grade properties is required.5. System Requirements5.1 Mechanical Device Requirements A mechanical device used as part of the grading process shall demonstrate the abilityto measure the mechanical or physical wood property used to segregate the lumber.5.2 Visual Requir
13、ements:5.2.1 Characteristics to be limited by visual evaluation, shall be documented as part of the qualification and quality controlprocedures. Such limitations shall be part of the grade requirements.5.2.2 Personnel conducting visual evaluations shall be qualified by the agency.6. Criteria for Gra
14、de Qualification6.1 General Requirements:6.1.1 A minimum of one assigned property of a grade shall be qualified by test. The grade assignment for properties qualifiedby test is given in 7.2.6.1.1.1 If the modulus of elasticity (MOE) is the only property assigned to a grade, it shall be evaluated by
15、test.6.1.1.2 If both strength and MOE properties are assigned to a grade, a minimum of one strength property and one MOE propertyshall be evaluated by test. If only one strength property is tested, that property shall be either the modulus of rupture (MOR) orultimate tensile stress (UTS).6.1.2 Each
16、grade shall be qualified at each size and for each species/species group.6.1.3 Sampling, evaluation, and presentation of data shall be in accordance with Practice D2915.6.2 Qualification Samples:6.2.1 The criteria for selecting qualification samples shall be documented and shall be in accordance wit
17、h 6.1.3.6.2.2 All qualification samples shall meet the visual requirements established for the grade.6.2.3 The minimum sample size for estimation of strength properties, and MOE shall be 53 specimens.6.2.4 The minimum sample size for estimation of mean or median property values, other than MOE, shal
18、l be 30 specimens.6.2.5 When the allowable shear stress parallel to grain (Fv) or the allowable compressive stress perpendicular to grain (Fc)are determined in accordance with 7.3.4 and 7.3.5, respectively, the specific gravity of a minimum of 30 qualification testspecimens shall be measured and rec
19、orded.6.3 Qualification Test Methods:D6570 1826.3.1 When mechanical and physical properties in Section 7 are determined by tests, the appropriate ASTM standards shall beused.6.3.1 Mechanical test methods shall be in accordance withWhen mechanical and physical properties in Section 7 TestMethodsare d
20、etermined D143,by D198, ortests, the D4761.appropriate ASTM standards shall be used:6.3.1.1 The determination of the MOE by edgewise bending shall employ third-point in accordance with Test Methods D4761.6.3.1.2 The determination of the MOE and MOR by edge-wiseedgewise bending shall employ third-poi
21、nt in accordance withTest Methods D4761.6.3.1.3 The determination of the MOE by flat-wise bending shall be in accordance with Test Methods D4761.6.3.1.4 The UTS of a sample shall be determined according to Test Methods D4761.6.3.1.5 The UTS of a sample shall be determined according to Test Methods D
22、4761. Whenever possible, a minimum gagelength of not less than 96 in. (2.44 m) shall be used. When determination of the tension parallel to the grain MOE is desired, testingshall be conducted according to the provisions of Test Methods D198.6.3.1.6 The determination of the ultimate shear strength pa
23、rallel to grain values shall be in accordance with Test Methods D143.6.3.1.7 The determination of the compression perpendicular to grain values shall be in accordance with Test Methods D143.6.3.2 Determination of the moisture content of the lumber sample shall be in accordance with Test Methods D444
24、2 or D7438.6.3.3 Specific gravity shall be based on weight and dimensions when oven dry as specified in Test Methods D2395.Measurements shall either be taken on oven-dried specimens, or at some other moisture content and the values adjusted to theoven-dry condition.6.3.4 Determination of the moistur
25、e content of the lumber sample shall be in accordance with Test Methods D4442 or D4444.7. Procedures for Assignment of Allowable Mechanical Properties and Specific Gravity7.1 Allowable mechanical properties and specific gravity shall be assigned using the qualification test procedures of 7.2, thepro
26、perty correlation procedures of 7.3, or the procedures of 7.4. These alternative procedures of 7.2 7.4 define the maximumproperty values, which are permitted to be assigned to a grade of mechanically graded lumber.7.1.1 Selection of the procedures specified in 7.1 to establish a value for any partic
27、ular property assigned to a grade is theprerogative of the grade specification author.7.1.2 The factors used in 7.2 and 7.3 apply to softwood lumber.7.1.3 If the Fb is to be an assigned property, it shall be determined by the test procedures of 7.2.7.1.4 Hardwood lumber species shall be reduced by t
28、he applicable factors in Practice D245, Table 8.7.1.4.1 Species containing interlocked grain shall have Fb,Ft, and Fc evaluated by test procedures of 7.2. Sample size selectionshall consider the evidence of interlocked grain and its representation in the sample.7.2 Assignment of Allowable Properties
29、 by Qualification Tests:7.2.1 Assignment of allowable properties by test shall follow the procedures of this section. Test results shall be evaluatedaccording to Practice D2915.7.2.1.1 Qualification tests are used to either establish allowable mechanical property values for new grades or to qualify
30、forpublished grade categories.7.2.2 Extreme Fiber Stress in Bending (Fb)The fifth percentile tolerance limit (75 % confidence) for the MOR of thequalification sample shall equal or exceed 2.1 times the assigned Fb value.7.2.3 Fiber Stress in Tension Parallel to Grain (Ft)The fifth percentile toleran
31、ce limit (75 % confidence) for the UTS of thequalification sample shall equal or exceed 2.1 times the assigned Ft value.7.2.4 Fiber Stress in Compression Parallel to Grain (Fc)The fifth percentile tolerance limit (75 % confidence) for ultimatecompressive strength parallel to grain (UCS) of the quali
32、fication sample shall equal or exceed 1.9 times the assigned Fc value.7.2.5 Shear Stress Parallel to Grain (Fv)The fifth percentile tolerance limit (75 % confidence) Fv for the qualification sampleshall equal or exceed 2.1 times the assigned Fv value.7.2.6 Modulus of ElasticityElasticity: The upper
33、95 % confidence interval of the qualification sample mean MOE shall equalor exceed the assigned grade MOE.7.2.6.1 The upper bound of the 95 % confidence interval of the qualification sample mean MOE shall meet or exceed theassigned grade MOE.7.2.6.2 For grades that include a near-minimum MOE specifi
34、cation, the sample parametric or non-parametric point estimate asdetermined in accordance with Practice D2915 shall equal or exceed the near-minimum MOE for the grade.7.2.7 Specific Gravity (SG)The upper bound of the 95 % confidence interval of the qualification sample mean specific gravityshall mee
35、t or exceed the assigned specific gravity value.7.2.8 Fiber Stress in Compression Perpendicular to Grain (Fc)The Fcshall be determined by test in accordance with TestMethods D143, and adjusted by the procedures of Practice D245.7.3 Assignment of Allowable Properties Based on Relationships:7.3.1 The
36、methods of 7.3 permit assignment of certain allowable properties based on recognized relationships between theassigned properties. This assignment shall be in accordance with the following procedures.7.3.2 Fiber Stress in Tension Parallel to Grain:D6570 1837.3.2.1 The maximum allowable Ft shall be a
37、ssigned in accordance with an established grade assignment model based on theassigned Fb, which has been published by the agency.7.3.2.2 In the absence of corroborative data, a maximum Ft/Fb ratio of 0.45 shall be used.7.3.3 Fiber Stress in Compression Parallel to Grain:7.3.3.1 The maximum allowable
38、 Fc shall be calculated from the following equation:Fc50.7098 Fb 12060.7!/1.9 (1)where:Fb = the assigned Fb for the grade.7.3.4 Shear Parallel to GrainThe Fv determined by a specific gravity-based model (see Appendix X1) is permitted when thespecific gravity is assigned in accordance with 7.2.7 or 7
39、.3.6.7.3.5 Fiber Stress in Compression Perpendicular to Grain (Fc)The Fcdetermined by a specific gravity-based model (seeAppendix X1) is permitted when specific gravity is assigned in accordance with 7.2.7 or 7.3.6.7.3.6 Specific GravityIt is permitted to assign specific gravity in accordance with a
40、 model that relates grading machinemeasurement to specific gravity. When such a model is used, the agency shall develop corroborative data to support theappropriateness of the assigned specific gravity.7.4 Assignment of Allowable Properties by Other Standards:7.4.1 The methods of 7.4 permit assignme
41、nt of certain allowable properties based on procedures in the appropriate ASTM andANSI standards.7.4.2 Shear Parallel to Grain StressThe Fv shall be assigned in accordance with the procedures of Practice D245 for visuallygraded solid sawn lumber of the same species or species group.7.4.3 Fiber Stres
42、s in Compression Perpendicular to GrainThe Fc shall be assigned in accordance with the procedures ofPractice D245 for visually graded solid sawn lumber of the same species or species group.7.4.4 Specific GravityThe specific gravity shall be assigned as reported in ANSI/AF mechanically graded lumber;
43、 solid sawn lumber; woodTABLE 1 Rounding Rules for Allowable Property ValuesMOE 100 000 psiFb 50 psi at 1000 psiand above25 psi below 1000 psiFt 25 psiFc 25 psiFc 5 psiFv 5 psiSG 0.01D6570 184APPENDIXES(Nonmandatory Information)X1. FORMULAS FOR DETERMINING THE SHEAR STRESS PARALLEL TO GRAIN AND FIBE
44、R STRESS IN COMPRES-SION PERPENDICULAR TO GRAINX1.1 Shear Stress Parallel to GrainX1.1.1 When qualified by measurement of the specific gravity (SG), the allowable stress in shear stress parallel to the grain (Fv)shall be calculated by a relationship between SG (based on oven dry weight/oven dry volu
45、me basis) and Fv:X1.1.2 For Douglas Fir, Douglas Fir-Larch, Douglas Fir-South, Hem-Fir, Southern Pine, Spruce-Pine-Fir (South),WesternWoods,and Western Cedars:Fv52663SG!140 (X1.1)X1.1.3 For Douglas Fir-Larch (N), Hem-Fir (N), and Spruce-Pine-Fir:Fv5284.83SG!126.6 (X1.2)where:SG = specific gravity (o
46、ven-dry weight/oven-dry volume basis)X1.2 Compression Perpendicular to the Grain (Fc) (0.04-in. deformation limit)X1.2.1 When qualified by measurement of the SG, the allowable stress shall be calculated by a relationship between SG (basedon oven dry weight/oven dry volume) and Fc:X1.2.1.1 For Dougla
47、s Fir, Douglas Fir-Larch, Douglas Fir-South, Hem-Fir, Southern Pine, Spruce-Pine-Fir (South), WesternWoods, and Western Cedars:Fc52252.43SG!2480 (X1.3)X1.2.1.2 For Douglas Fir-Larch (N), Hem-Fir (N), and Spruce-Pine-Fir:Fc52243.83SG!2473.8 (X1.4)X1.3 Compression Perpendicular to the Grain (Fc) (0.02
48、-in. deformation limit)X1.3.1 Refer to the appropriate agency grading rules for equations to adjust the Fcfrom a 0.04-in. deformation limit to a 0.02-in.deformation limit.D6570 185X2. EXPLANATION OF SOLID SAWN LUMBER PRODUCTS CURRENTLY PRODUCED IN THE UNITED STATES ANDCANADA BY NONDESTRUCTIVE EVALUA
49、TIONX2.1 Mechanically Graded LumberX2.1.1 GeneralThe process where each piece of lumber is nondestructively evaluated by a machine to determine the value ofthe sorting parameter or grading algorithm. Mechanically graded lumber also is required to meet certain visual requirements. Theprocess assigns strength and MOE values based on a model that combines information from the nondestructive parameter andvisual characteristics. One exception is E-rated lumber; strength values are not assigned to E-rated lumber.X2.2 Machine Stress-Rated LumberX2.2
