Format Conversion Factor (LRFD Only) Explained:
Used in Sawn Lumber Design, Glu Lam Design, Round Timber/Poles Design?, etc, the format conversion factor (KF) is used to adjust reference ASD? design values to LRFD? reference resistances. By using LRFD in lieu of ASD design you are substituting three variables for one, therefore I normally recommend ASD as being the superior choice for wood design.
Note: The LRFD load combinations for wood are found either in the governing building code (e.g. IBC, UBC, etc.), or those LRFD load combinations specified in the ASCE 7-05.
Format Conversion Factors (KF)[1]
| Table 1: Format Conversion Factors (KF) | ||
| Application | Property | KF |
| Members | Fb, Ft, Fv, Fc, Frt, Fs | 2.16/φ |
| Fc-p | 1.875/φ | |
| Emin | 1.5/φ | |
| Connections | (all connections) | 2.16/φ |
where:
phi (φ) = the wood resistance factor (LRFD only)
Note: KF is not applicable where the LRFD design values are determined in accordance with the reliability normalization factor method (ASTM D 5457).
References:
- American Forest and Paper Association, "National Design Specification for Wood Construction", 2005
- Found in Appendix N.