The provisions of NDS Chapter 16 and FDS Chapter 3 are intended to allow the designer to use analytical methods to establish the fire resistance time associated with a wood member or assembly tested to an ASTM E119 fire exposure. In this mechanics-based design method, wood design properties intended for structural design are adjusted to nominal strengths for fire resistance calculations. These nominal strengths are used with cross-sections, reduced due to charring of the wood, to calculate the time to structural failure of a wood member or assembly. As such, application of the slenderness limits intended to provide safe structural designs to provisions for estimating structural failure time is unnecessary and would reduce accuracy of the estimated failure time. Reference to the equation 3.7-1 is provided within Chapter 16 to remind the user that the stability equations should be applied in the design of columns. Reference to the stability equations like 3.7-1 were only to remind the user that stability equations should be applied, but not intended to require application of design slenderness ratio limitations that are specific to structural design. As stated in NDS Commentary Section C16.1, these provisions do not address procedures for evaluating members for continued service following fire damage.
When performing fire design in accordance with NDS Chapter 16, should the slenderness ratio limits specified in NDS Chapter 3 be applied to columns and bending members?