1、Designation: D5457 17Standard Specification forComputing Reference Resistance of Wood-Based Materialsand Structural Connections for Load and Resistance FactorDesign1This standard is issued under the fixed designation D5457; the number immediately following the designation indicates the year oforigin
2、al adoption 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.INTRODUCTIONLoad and resistance factor design (LRFD) is a structural design m
3、ethod that uses concepts fromreliability theory and incorporates them into a procedure usable by the design community. The basicdesign equation requires establishing a reference resistance based on several material propertyparameters. A standard method for calculating the required material property
4、input data is critical sothat all wood-based structural materials can be treated equitably. This specification provides theprocedures that are required for the generation of reference resistance for LRFD.1. Scope1.1 This specification covers procedures for computing thereference resistance of wood-b
5、ased materials and structuralconnections for use in load and resistance factor design(LRFD). The format conversion procedure is outlined inSection 4. The test-based derivation procedure is outlined inAnnex A1. The reference resistance derived from this specifi-cation applies to the design of structu
6、res addressed by the loadcombinations in ASCE 7-10.1.2 A commentary to this specification is provided inAppendix X1.1.3 UnitsThe values stated in inch-pound units are to beregarded as the standard. The values given in parentheses aremathematical conversions to SI units that are provided forinformati
7、on only and are not considered standard.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World
8、 Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D9 Terminology Relating to Wood and Wood-Based Prod-uctsD143 Test Methods for Small Clear Specimens of TimberD198 Test Methods of Static Tests of Lumber in StructuralSizesD1037 Test Methods for
9、Evaluating Properties of Wood-Base Fiber and Particle Panel MaterialsD1761 Test Methods for Mechanical Fasteners in WoodD1990 Practice for Establishing Allowable Properties forVisually-Graded Dimension Lumber from In-Grade Testsof Full-Size SpecimensD2718 Test Methods for Structural Panels in Planar
10、 Shear(Rolling Shear)D2719 Test Methods for Structural Panels in Shear Through-the-ThicknessD2915 Practice for Sampling and Data-Analysis for Struc-tural Wood and Wood-Based ProductsD3043 Test Methods for Structural Panels in FlexureD3500 Test Methods for Structural Panels in TensionD3501 Test Metho
11、ds for Wood-Based Structural Panels inCompression1This specification is under the jurisdiction of ASTM Committee D07 on Woodand is the direct responsibility of Subcommittee D07.02 on Lumber and EngineeredWood Products.Current edition approved Nov. 1, 2017. Published December 2017. Originallyapproved
12、 in 1993. Last previous edition approved in 2015 as D5457 15. DOI:10.1520/D5457-17.2For 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 pa
13、ge onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for t
14、heDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.148 D3737 Practice for Establishing Allowable Properties forStructural Glued Laminated Timber (Glulam)D4761 Test Methods for Mechanical Properties o
15、f Lumberand Wood-Base Structural MaterialD5055 Specification for Establishing and Monitoring Struc-tural Capacities of Prefabricated Wood I-JoistsD5456 Specification for Evaluation of Structural CompositeLumber ProductsE105 Practice for Probability Sampling of Materials2.2 ASCE Standard:3ASCE 7-10 M
16、inimum Design Loads for Buildings and OtherStructures3. Terminology3.1 Definitions:3.1.1 For general definitions of terms related to wood, referto Terminology D9.3.2 Definitions of Terms Specific to This Standard:3.2.1 coeffcient of variation, CVwa relative measure ofvariability based on the shape p
17、arameter of the 2-parameterWeibull distribution.3.2.1.1 DiscussionIt is not the traditional sample standarddeviation of the data divided by the sample mean.3.2.2 data confidence factor, a factor that is used toadjust member reference resistance for sample variability andsample size.3.2.3 distributio
18、n percentile, Rpthe value of the distribu-tion associated with proportion, p, of the cumulative distribu-tion function.3.2.4 factored resistance, Rnthe product of the resis-tance factor and the reference or nominal resistance notincluding the time effect factor () and other adjustments forend-use co
19、nditions.3.2.5 format conversion factor, KFa factor applied toconvert resistance from the allowable stress design (ASD)format to the LRFD format.3.2.6 lower taila portion of an ordered data set consistingof all test specimens with the lowest property values (forexample, lowest strengths).3.2.7 nomin
20、al resistancea term equivalent to the referenceresistance used in reliability analysis and LRFD standards.3.2.8 reference resistance, Rnthe design value used inLRFD equations to represent member resistance prior toapplication of the resistance factor, the time effect factor (),and other adjustments
21、for end-use conditions.3.2.8.1 DiscussionThe reference value represents memberresistance at 10-minute load duration.3.2.9 reliability normalization factor, KRa factor used toestablish the reference resistance to achieve a target reliabilityindex for a reference set of conditions.3.2.10 resistance fa
22、ctor, a factor applied to the resistanceside of the LRFD equation.4. Reference Resistance for LRFD4.1 Reference resistance for LRFD shall be determinedusing one of the following procedures:4.1.1 Format conversion per Section 4.2;or4.1.2 Test-based derivation per Annex A1.4.2 Format Conversion Proced
23、ure:4.2.1 Resistance values for LRFD are permitted to be basedon format conversion from code-recognized allowable stressdesign (ASD). It shall not be claimed that reference resistancevalues generated in this manner achieve a stated reliabilityindex. Resistance factors for determining LRFD factoredre
24、sistance, Rn, are given in Table 1.NOTE 1Examples of standards that are used to generate code-recognized ASD values include Test Methods D143, D198, D1037,D1761, D2718, D2719, D3043, D3500, D3501, and D4761; PracticesD1990 and D3737; and Specifications D5055 and D5456.4.2.2 For standardization purpo
25、ses, format conversion ref-erence resistance values shall be based on the arithmeticconversion at a specified reference condition that results fromthe calibration (defined as providing an identical requiredsection modulus, cross-sectional area, allowable load capacity,and so forth) of basicASD and L
26、RFD equations. The specifiedreference condition shall be chosen such that changes in designcapacity over the range of expected load cases and load ratiosis minimized.4.2.3 Values of the format conversion factor, KF, are givenin Table 2.4.2.4 The format conversion reference resistance is com-puted by
27、 multiplying the ASD resistance by KF. For membersand connections, the ASD resistance is based on a normal(10-year) load duration. For shear walls and diaphragms, theASD resistance is based on a 10-minute load duration.4.2.5 For lateral buckling (stability), compression perpen-dicular to grain, and
28、rolling shear that is not subject to loadduration or time effect adjustments, the value of KFis based onthe assumption that neither the ASD nor LRFD resistancevalues are modified by duration of load or time effect adjust-ments.4.2.6 Format Conversion ExampleAn ASD bolt designvalue for a single shear
29、 connection, Fx, is 800 lbf (3.56 kN)(based on normal 10-year load duration). From Table 2, theformat conversion factor, KF, is 3.32. The correspondingLRFD bolt reference resistance value is as follows:Rn5 KF3 Fx5 3.32 3800 5 2658 lbf 11.82 kN! (1)4.2.7 Format Conversion Example for Shear Walls orDi
30、aphragmsAnASD shear wall design value, Fx, is 395 lb/ft(5.76 kN/m) (based on a 10-minute load duration). From Table3Available from The American Society of Civil Engineers (ASCE), 1801Alexander Bell Dr., Reston, VA 20191.TABLE 1 Specified LRFD Resistance Factors, sApplication Property sMembers compre
31、ssionA0.90bending, lateral buckling (stability) 0.85tension parallel 0.80shear, radial tension 0.75Connections all 0.65Shear Walls, diaphragms shear 0.80ACompressionparallel-to-grain,compressionperpendicular-to-grain,andbearing.D5457 17248 2, the format conversion factor, KF, is 2.00. The correspond
32、ingLRFD shear wall reference resistance value is as follows:Rn5 KF3 Fx5 2.00 3395 5 790 lbft 11.53 kN/m! (2)5. Keywords5.1 format conversion; load and resistance factor design(LRFD); reference resistance; structural connections; test-based derivation; wood-based materialsANNEX(Mandatory Information)
33、A1. TEST-BASED DERIVATION OF REFERENCE RESISTANCE FOR LRFDA1.1 Parameters required for the derivation of referenceresistance are presented in this Annex. These parametersinclude the distribution percentile, Rp, coefficient of variation,CVw, data confidence factor, , and reliability normalizationfact
34、or, KR. An example derivation of reference resistance isprovided in X1.8.5.A1.2 Sampling:A1.2.1 Samples selected for analysis and implementationwith this specification shall be representative of the populationabout which inferences are to be made. Both manufacturingand material source variability sh
35、all be considered. The prin-ciples of Practice E105 shall be maintained. Practice D2915provides methods for establishing a sampling plan. Specialattention is directed to sampling procedures in which thevariability is low and results can be influenced significantly bymanufacturing variables. It is es
36、sential that the sampling planaddresses the relative magnitude of the sources of variability.A1.2.1.1 Data generated from a quality control programshall be acceptable if the criteria of A1.2.1 are maintained.A1.2.1.2 Multiple Data SetsWhen data from multiple datasets are compiled or grouped, the cri
37、teria used to group suchdata shall be in accordance with the provisions of A1.2.1.When such procedures are available in applicable productstandards, they shall be used.A1.2.2 Sample Size:A1.2.2.1 For data sets in which all specimens are tested tofailure, the minimum sample size shall be 30.NOTE A1.1
38、The confidence with which population properties can beestimated decreases with decreasing sample size. For sample sizes lessthan 60, extreme care must be taken during sampling to ensure arepresentative sample.A1.2.2.2 For lower tail data sets, a minimum of 60 failedobservations is required for sampl
39、e sizes of n = 600 or less.This represents at least the lower 10 % of the distribution. Forsample sizes greater than 600, a minimum of the lowest 10 %of the distribution is required. For example, sample size,n = 720, 0.10 (720) = 72 failed test specimens in the lower tail.Only parameter estimation p
40、rocedures designed specifically forlower tail data sets shall be used (see Appendix X2).A1.3 Testing:A1.3.1 Testing shall be conducted in accordance with ap-propriate standard testing procedures. The intent of the testingshall be to develop data that represent the capacity of theproduct under standa
41、rd conditions.A1.3.2 Periodic Property AssessmentPeriodic testing isrecommended to verify that the properties of productionmaterial remain representative of published properties.A1.4 Reference Resistance, RnThe following equationestablishes reference resistance for LRFD:Rn5 Rp3 3 KR(A1.1)where:Rp= d
42、istribution percentile estimate, = data confidence factor, andKR= reliability normalization factor.A1.4.1 Distribution Percentile Estimate, Rp:A1.4.2 Eq A1.2 is intended to be used to calculate anypercentile of a two-parameter Weibull distribution. The per-centile of interest depends on the property
43、 being estimated.Rp5 -ln 1 2 p!#1(A1.2)where: = Weibull scale parameter,p = percentile of interest expressed as a decimal (forexample, 0.05), andTABLE 2 Format Conversion Factor, KFProperty KFCompression Parallel to Grain 2.40Bending 2.54Tension Parallel to Grain 2.70Shear 2.88ARadial Tension 2.88Co
44、nnections 3.32Lateral Buckling (Stability) 1.76Compression Perpendicular to Grain 1.67Shear Wall and Diaphragm Shear 2.00BAThe value of the format conversion factor is 2.00 where shear is not subject toload duration or time effect adjustments (e.g., rolling shear in cross-laminatedtimber).BThe forma
45、t conversion factor for shear wall and diaphragm shear is only intendedto be applied to the design capacity of shear wall or diaphragm assemblies, not tothe design of individual members or subcomponents of these assemblies.D5457 17348 = Weibull shape parameter.A1.4.3 The shape () and scale () parame
46、ters of thetwo-parameter Weibull distribution shall be established todefine the distribution of the material resistance (1).4Algo-rithms for common estimation procedures are provided inAppendix X2.A1.4.4 Coeffcient of Variation, CVwThe coefficient ofvariation of the material is necessary when determ
47、ining thedata confidence factor, , and the reliability normalizationfactor, KR. The CVwcan be estimated from the shape parameterof the Weibull distribution as follows:CVw20.92(A1.3)NOTE A1.2The above approximation is within 1 % of the exactsolution for CVwvalues between 0.09 and 0.50. An exact relat
48、ionship ofCVwand is shown in Appendix X3.A1.5 Data Confidence Factor, The data confidencefactor, , accounts for uncertainty associated with data sets (2).This factor, which is a function of coefficient of variation,sample size, and reference percentile, is applied as a multiplieron the distribution
49、estimate. Table A1.1 provides data confi-dence factors appropriate for lower fifth-percentile estimates.NOTE A1.3When a distribution tolerance limit is developed on a basisconsistent with , the data confidence factor is taken as unity.A1.6 Reliability Normalization Factor, KRThe reliabilitynormalization factor, KR, which is a function of CVwand isgenerated for specific target reliability indices, is used to adjustthe distribution estimate (for example, R0.05) to achieve a targetreliability index.The reliabi
