1、Designation: D5457 15D5457 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
2、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
3、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 p
4、roperty 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 the reference resistance
5、of wood-based materials and structuralconnections for use in load and resistance factor design (LRFD). The format conversion procedure is outlined in Section 4. Thetest-based derivation procedure is outlined in Annex A1. The reference resistance derived from this specification applies to thedesign o
6、f structures addressed by the load combinations in ASCE 7-10.1.2 A commentary to this specification is provided in Appendix X1.1.3 UnitsThe values stated in inch-pound units are to be regarded as the standard. The values given in parentheses aremathematical conversions to SI units that are provided
7、for information only and are not considered standard.1.4 This international 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
8、the World Trade Organization Technical Barriers to Trade (TBT) Committee.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 SizesD1037 Test Me
9、thods for Evaluating Properties of Wood-Base Fiber and Particle Panel MaterialsD1761 Test Methods for Mechanical Fasteners in WoodD1990 Practice for EstablishingAllowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-SizeSpecimensD2718 Test Methods for Structural Panels
10、 in Planar Shear (Rolling Shear)D2719 Test Methods for Structural Panels in Shear Through-the-ThicknessD2915 Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based ProductsD3043 Test Methods for Structural Panels in Flexure1 This specification is under the jurisdiction ofASTM Com
11、mittee D07 on Wood and is the direct responsibility of Subcommittee D07.02 on Lumber and Engineered WoodProducts.Current edition approved May 1, 2015Nov. 1, 2017. Published June 2015December 2017. Originally approved in 1993. Last previous edition approved in 20122015 asD5457 12.D5457 15. DOI: 10.15
12、20/D5457-15.10.1520/D5457-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM sta
13、ndard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cas
14、es only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D3500 Test Methods for Structural Panels in TensionD3501 Test Methods for Wood-B
15、ased Structural Panels in CompressionD3737 Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)D4761 Test Methods for Mechanical Properties of Lumber and Wood-Base Structural MaterialD5055 Specification for Establishing and Monitoring Structural Capacities of
16、 Prefabricated Wood I-JoistsD5456 Specification for Evaluation of Structural Composite Lumber ProductsE105 Practice for Probability Sampling of Materials2.2 ASCE Standard:3ASCE 7-10 Minimum Design Loads for Buildings and Other Structures3. Terminology3.1 Definitions:3.1.1 For general definitions of
17、terms related to wood, refer to Terminology D9.3.2 Definitions:Definitions of Terms Specific to This Standard:3.1.1 For general definitions of terms related to wood, refer to Terminology D9.3.2.1 coeffcient of variation, CVwa relative measure of variability. For this specification, the calculation o
18、f variability CVwis based on the shape parameter of the 2-parameter Weibull distribution. It is not the traditional sample standard deviation of thedata divided by the sample mean.3.2.1.1 DiscussionIt is not the traditional sample standard deviation of the data divided by the sample mean.3.2.2 data
19、confidence factor, a factor that is used to adjust member reference resistance for sample variability and samplesize.3.2.3 distribution percentile, Rpthe value of the distribution associated with proportion, p, of the cumulative distributionfunction.3.2.4 factored resistance, Rnthe product of the re
20、sistance factor and the reference or nominal resistance not including thetime effect factor () and other adjustments for end-use conditions.3.2.5 format conversion factor, KFa factor applied to convert resistance from the allowable stress design (ASD) format to theLRFD format.3.2.6 lower taila porti
21、on of an ordered data set consisting of all test specimens with the lowest property values (for example,lowest strengths).3.2.7 nominal resistancea term equivalent to the reference resistance used in reliability analysis and LRFD standards.3.2.8 reference resistance, Rnthe design value used in LRFD
22、equations to represent member resistance (that is, strength orcapacity).prior to application of the resistance factor, the time effect factor (), and other adjustments for end-use conditions.3.2.8.1 DiscussionThe reference value represents member resistance at 10-minute load duration.3.2.9 reliabili
23、ty normalization factor, KRa factor used to establish the reference resistance to achieve a target reliability indexfor a reference set of conditions.3.2.10 resistance factorfactor, a factor applied to the resistance side of the LRFD equation.4. Sampling4.1 Samples selected for analysis and implemen
24、tation with this specification shall be representative of the population aboutwhich inferences are to be made. Both manufacturing and material source variability shall be considered. The principles of PracticeE105 shall be maintained. Practice D2915 provides methods for establishing a sampling plan.
25、 Special attention is directed tosampling procedures in which the variability is low and results can be influenced significantly by manufacturing variables. It isessential that the sampling plan address the relative magnitude of the sources of variability.4.1.1 Data generated from a quality control
26、program shall be acceptable if the criteria of 4.1 are maintained.4.1.2 When data from multiple data sets are compiled or grouped, the criteria used to group such data shall be in keeping withthe provisions of 4.1. When such procedures are available in applicable product standards, they shall be use
27、d.4.2 Sample Size:3 Available from The American Society of Civil Engineers (ASCE), 1801 Alexander Bell Dr., Reston, VA 20191.D5457 1724.2.1 For data sets in which all specimens are tested to failure, the minimum sample size shall be 30.NOTE 1The confidence with which population properties can be est
28、imated decreases with decreasing sample size. For sample sizes less than 60,extreme care must be taken during sampling to ensure a representative sample.4.2.2 For lower tail data sets, a minimum of 60 failed observations is required for sample sizes of n = 600 or less. (Thisrepresents at least the l
29、ower 10 % of the distribution.) For sample sizes greater than 600, a minimum of the lowest 10 % of thedistribution is required (for example, sample size, n = 720, 0.10 (720) = 72 failed test specimens in the lower tail). Only parameterestimation procedures designed specifically for lower tail data s
30、ets shall be used (see Appendix X2).5. Testing5.1 Testing shall be conducted in accordance with appropriate standard testing procedures. The intent of the testing shall be todevelop data that represent the capacity of the product in service.5.2 Periodic Property AssessmentPeriodic testing is recomme
31、nded to verify that the properties of production material remainrepresentative of published properties.4. Reference Resistance for LRFD6.1 The derivation of LRFD reference resistance is addressed in this section. Parameters required for the derivation of referenceresistance are also presented. These
32、 parameters include the distribution percentile, coefficient of variation, data confidence factor,and reliability normalization factor. An example derivation of reference resistance is provided in X1.7.6.2 Reference Resistance, RnThe following equation establishes reference resistance for LRFD:Rn 5R
33、p 33KR (1)where:Rp = distribution percentile estimate, = data confidence factor, andKR = reliability normalization factor.4.1 Distribution Percentile Estimate, Rp: Reference resistance for LRFD shall be determined using one of the followingprocedures:4.1.1 Eq 2 is intended toFormat conversion per Se
34、ction 4.2be used to calculate any percentile of a two-parameter Weibulldistribution. The percentile of interest depends on the property being estimated.; orRp 52ln12p!#1/ (2)where: = Weibull scale parameter,p = percentile of interest expressed as a decimal (for example, 0.05), and = Weibull shape pa
35、rameter.4.1.2 The shape (Test-based derivation per) and scale ( ) parameters of the two-parameter Weibull distribution shall beestablished to define the distribution of the material resistance. Algorithms for common estimation procedures are provided inAppendix X2Annex A1.6.4 Coeffcient of Variation
36、, CVwThe coefficient of variation of the material is necessary when determining the data confidencefactor, , and the reliability normalization factor, KR. The CVw can be estimated from the shape parameter of the Weibulldistribution as follows:CVw20.92 (3)NOTE 2The above approximation is within 1 % o
37、f the exact solution for CVw values between 0.09 and 0.50. An exact relationship of CVw and isshown in Appendix X3.6.5 Data Confidence Factor, The data confidence factor, , accounts for uncertainty associated with data sets.5 This factor,which is a function of coefficient of variation, sample size,
38、and reference percentile, is applied as a multiplier on the distributionestimate. Table 1 provides data confidence factors appropriate for lower fifth-percentile estimates.NOTE 3When a distribution tolerance limit is developed on a basis consistent with , the data confidence factor is taken as unity
39、.6.6 Reliability Normalization Factor, KRThe reliability normalization factor, KR, is used to adjust the distribution estimate (forexample, R0.05) to achieve a target reliability index. The reliability normalization factor is the ratio of the computed resistancefactor, c (X1.7), to the specified res
40、istance factor, s (Table 2), adjusted by a scaling factor. This adjustment factor is a functionof CVw and is generated for specific target reliability indices. The KR values presented in Table 3 represent resistance factors (c)computed at a live-to-dead load ratio of 3. Computations for determining
41、reliability normalization factors for target reliabilityindices greater than = 2.4 are contained in Zahn.64.2 Format Conversion: Conversion Procedure:D5457 1734.2.1 As an alternative to the use of Resistance KR, in which one chooses to adjust the design values to achieve a statedreliability index un
42、der the reference load conditions, it is permissible to generate LRFD reference resistance values values forLRFD are permitted to be based on format conversion from code-recognized allowable stress design (ASD). It shall not be claimedthat reference resistance values generated in this manner achieve
43、 a stated reliability index. Resistance factors for determiningLRFD factored resistance, 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; Practices D19
44、90 and D3737; and Specifications D5055 and D5456.4.2.2 For standardization purposes, format conversion reference resistance values shall be based on the arithmetic conversionat a specified reference condition that results from the calibration (defined as providing an identical required section modul
45、us,cross-sectional area, allowable load capacity, and so forth) of basic ASD and LRFD equations. The specified reference conditionshall be chosen such that changes in design capacity over the range of expected load cases and load ratios is minimized.4.2.3 Values of the format conversion factor, KF,
46、are given in Table 42.4.2.4 The format conversion reference resistance is computed by multiplying the ASD resistance by KF. For members andconnections, theASD resistance is based on a normal (10-year) load duration. For shear walls and diaphragms, theASD resistanceis based on a 10-minute load durati
47、on.4.2.5 For lateral buckling (stability), compression perpendicular to grain, and rolling shear that is not subject to load durationor time effect adjustments, the value of KF is based on the assumption that neither the ASD nor LRFD resistance values aremodified by duration of load or time effect a
48、djustments.4.2.6 Format Conversion ExampleAn ASD bolt design value for a single shear connection, Fx, is 800 lbf (3.56 kN) (basedon normal 10-year load duration). From Table 42, the format conversion factor, KF, is 3.32. The corresponding LRFD boltreference resistance value is as follows:Rn 53.32380
49、0 (1)Rn 52658 lbfRn 5KF 3Fx 53.32380052658 lbf 11.82 kN! (1)4.2.7 Format Conversion Example for Shear Walls or DiaphragmsAn ASD shear wall design value, Fx, is 395 lb/ft (5.76kN/m) (based on a 10-minute load duration). From Table 42, the format conversion factor, KF, is 2.00. The corresponding LRFDshear wall reference resistance value is as follows:Rn 52.003395 (2)Rn 5790 lb/ftRn 5KF 3Fx 52.0033955790 lbft 11.53 kN/m! (2)7. Presentation of Results7.1 Report the sampling plan and testing in accordance with applicable st
