Adaptive upper-bound pushover analysis for high-rise moment steel frames

In this paper, a new nonlinear static analysis procedure is proposed to assess the seismic performance of tall buildings, which considers both the higher modes effects as well as the progressive changes in the dynamic characteristics of structures during the inelastic response. In this method, the applied load pattern computed using the upper-bound (UB) method is updated at each analysis step considering only the first two modes of vibration and corrected by combining this applied load pattern with a uniform load distribution. The accuracy of the proposed adaptive upper-bound (AUB) procedure is tested using four steel moment resisting frame buildings. The results from the (AUB) are compared to those of the (UB) pushover analysis, improved upper-bound (IUB) method, modal pushover analysis (MPA), displacement-based adaptive pushover (DAP) procedure, and the nonlinear time history analysis (NTHA). In most cases, the proposed procedure leads to more adequate results and closer to those obtained by NTHA.