This specification covers procedures for computing the reference resistance of wood-based materials and structural connections for use in load and resistance factor design (LRFD). Parameters required for the derivation of reference resistance are presented. These parameters include the distribution percentile, coefficient of variation, data confidence factor, and reliability normalization factor. The shape and scale parameters of the two-parameter Weibull distribution shall be established to define the distribution of the material resistance. The data confidence factor accounts for uncertainty associated with data sets. This factor, which is a function of coefficient of variation, sample size, and reference percentile, is applied as a multiplier on the distribution estimate. The reliability normalization factor is used to adjust the distribution estimate to achieve a target reliability index. The reliability normalization factor is the ratio of the computed resistance factor to the specified resistance factor, adjusted by a scaling factor.

1.1 This specification covers procedures for computing the reference resistance of wood-based materials and structural connections for use in load and resistance factor design (LRFD). The format conversion procedure is outlined in Section 4. The test-based derivation procedure is outlined in Annex A1. The reference resistance derived from this specification applies to the design of structures addressed by the load combinations in ASCE 7-16.

1.2 A commentary to this specification is provided in Appendix X1.

1.3 Units—The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.