What is the purpose of the NDS Format Conversion Factor, K_F?

• The NDS Format Conversion Factor, K_F , converts reference design values (allowable stress design values based on normal load duration) to LRFD reference resistances as described in ASTM D5457 Standard Specification for Computing Reference Resistance of Wood-Based Materials and Structural Connections for Load and Resistance Factor Design. The expression for K_F is a constant divided by the resistance factor, φ, and includes the following:
  1) a conversion factor to adjust an allowable design value to a strength level design value (embedded in the constant),
  2) a conversion factor to adjust from a 10 year (long-term) load duration to a 10 minute (short-term) load duration basis (embedded in the constant), and
  3) a conversion factor to adjust for a specified resistance factor, φ (expressed independently in the denominator).