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Adjustment Factors
From NDS Table 16.2.2, the fire strength adjustment factors of 2.58 for fc and 2.85 for ft are applied.
Effective Stiffness
The effective stiffness EIeff used in determining the buckling resistance PcE is calculated using the fire-reduced section as described in Effective Stiffness, above.
Effective Area
The effective area used to determine design stresses fc and ft , the slenderness ratio, and axial compressive resistance Pc* is that of the fire-reduced cross section.
Effective Moment of Inertia
The effective moment of inertia Ieff used for the slenderness factor is calculated using the reduced section.
Out-of-Plane Deflection
The value of the out-of-plane deflection used for combined axial and bending includes the load eccentricity, that is, the distance from the location of the axial load to the centroid of the fire-reduced section. For this reason, combined-axial-and-bending compression design is always calculated for fire design, even when there was initially no load eccentricity or lateral loads.