STABILITY ANALYSIS OF THE SEISMIC RESPONSE OF HIGH RISE STEEL BUILDINGS INCLUDING P-DELTA EFFECTS

The objective of this study was to investigate the effect of P-Delta analysis on the static and dynamic stability analysis of high rise steel buildings subjected to earthquake excitation. Different building models including ten,twenty, thirty, forty and fifty story composite steel buildings with symmetrical and asymmetrical layouts were analyzed. Finite element approach by using ETABS software was used to conduct this study.Different parameters were investigated including number of stories, structural elements stiffness, and bracing system. The second-order analysis, which includes geometric nonlinearity and P-Delta effect, used tocheck the adequacy of the amplified first-order analysis proposed by AISC specification for stability and strength design. Second-order analysis with linear and nonlinear time-history, including P-Delta effects wasaccounted for. The numerical analysis results presented reveal that the stability coefficient approach introduced in the ASCE 7-10 standard to consider P-Δ effects in the design and analysis of structures appears to beoverly conservative. A maximum stability coefficient (θmax) greater than 0.25 would be necessary to account for P-Delta effects. This depends on the type of loading, number of stories, type of analysis as static or dynamic and shape of the buildings as symmetrical or asymmetrical.

Keywords:

Dynamic Analysis , High-Rise Building , Finite Element , P-Delta Effect , Stability