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 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 (´) indicates an editorial change since the last revision or reapproval.INTRODUCTIONLoad and resistance factor design (LRFD) is a structural design method 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 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-based 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 structures addressed by the loadcombinations in ASCE 7-10.1.2 A commentary to this specification is provided inAppendix X1.1.3 Units—The 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 forinformation 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 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 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 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 Methods 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 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

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United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1D3737 Practice for Establishing Allowable Properties forStructural Glued Laminated Timber (Glulam)D4761 Test Methods for Mechanical Properties of 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 Minimum 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 coeffıcient of variation, CVw—a relative measure ofvariability based on the shape parameter of the 2-parameterWeibull distribution.3.2.1.1 Discussion—It is not the traditional sample standarddeviation of the data divided by the sample mean.3.2.2 data confidence factor, Ω—a factor that is used toadjust member reference resistance for sample variability andsample size.3.2.3 distribution percentile, Rp—the value of the distribu-tion associated with proportion, p, of the cumulative distribu-tion function.3.2.4 factored resistance, ϕ Rn—the product of the resis-tance factor and the reference or nominal resistance notincluding the time effect factor (λ) and other adjustments forend-use conditions.3.2.5 format conversion factor, KF—a factor applied toconvert resistance from the allowable stress design (ASD)format to the LRFD format.3.2.6 lower tail—a portion of an ordered data set consistingof all test specimens with the lowest property values (forexample, lowest strengths).3.2.7 nominal resistance—a term equivalent to the referenceresistance used in reliability analysis and LRFD standards.3.2.8 reference resistance, Rn—the design value used inLRFD equations to represent member resistance prior toapplication of the resistance factor, the time effect factor (λ),and other adjustments for end-use conditions.3.2.8.1 Discussion—The reference value represents memberresistance at 10-minute load duration.3.2.9 reliability normalization factor, KR—a factor used toestablish the reference resistance to achieve a target reliabilityindex for a reference set of conditions.3.2.10 resistance factor, ϕ—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 Procedure: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 factoredresistance, ϕRn, are given in Table 1.NOTE 1—Examples 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 purposes, 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 LRFD 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 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 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 Example—An ASD bolt designvalue for a single shear 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 orDiaphragms—AnASD 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, ϕsApplication Property ϕsMembers compressionA0.90bending, 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 − 1722, the format conversion factor, KF, is 2.00. The correspondingLRFD shear wall reference resistance value is as follows:Rn5 KF3 Fx5 2.00 3395 5 790 lb⁄ft ~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)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, Ω, and reliability normalizationfactor, 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 shall 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 essential 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 Sets—When data from multiple datasets are compiled or grouped, the criteria 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—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 sample 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 procedures 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 standard conditions.A1.3.2 Periodic Property Assessment—Periodic testing isrecommended to verify that the properties of productionmaterial remain representative of published properties.A1.4 Reference Resistance, Rn—The following equationestablishes reference resistance for LRFD:Rn5 Rp3Ω 3 KR(A1.1)where:Rp= distribution percentile estimate,Ω = 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 being estimated.Rp5 η@-ln ~1 2 p!#1⁄α(A1.2)where:η = 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 2.88Connections 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 format 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 − 173α = Weibull shape parameter.A1.4.3 The shape (α) and scale (η) parameters 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 Coeffıcient of Variation, CVw—The coefficient ofvariation of the material is necessary when determining thedata confidence factor, Ω, and the reliability normalizationfactor, KR. The CVwcan be estimated from the shape parameterof the Weibull distribution as follows:CVwα20.92(A1.3)NOTE A1.2—The above approximation is within 1 % of the exactsolution for CVwvalues between 0.09 and 0.50. An exact relationship ofCVwand α is shown in Appendix X3.A1.5 Data Confidence Factor, Ω—The data confidencefactor, Ω, 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 estimate. Table A1.1 provides data confi-dence factors appropriate for lower fifth-percentile estimates.NOTE A1.3—When a distribution tolerance limit is developed on a basisconsistent with Ω, the data confidence factor is taken as unity.A1.6 Reliability Normalization Factor, KR—The 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 reliability normalization factor