Second-Order Analysis and Design of Wall-Framed Structures Allowing for Imperfections

Abstract

In design of steel structures including bare steel frames, composite steel-concrete structures and those with walls and slabs, the conventional method considers each member separately and the effective length is then assumed for member resistance check. This involves inconsistency between the analysis method and the design method. The primitive and rather inadequate second-order P-Δ-only analysis considering only the sway effect has been used extensively in industry and in many computer programs. However, as the P-δ effect for member bowing is ignored, the effective length is still required to be assumed for every member. Researchers in PolyU have completed the second-order P-Δ-δ analysis and design method for bare steel frames and recent research has been directed to the design of walled frames such that the effective length is not required for flexural buckling check. In this paper, the structural shear wall is modeled by finite shell element whereas the imperfect stability function is employed to model beam-column members. The slab is proposed to be modeled by efficient floor elements. The model is compared well with the results by others. The P-δ effect for member bowing is considered so that the section capacity check alone is sufficient to check the structural adequacy without the assumption of effective length, classification of sway and non-sway frame mode and the tedious individual member resistance check.