Simplified multimodal pushover target acceleration method for seismic resistance analysis of medium-rise RC structures

This paper presents a simplified target acceleration method, which is a new modification of the multimodal pushover method. Target acceleration is defined as the minimum acceleration of a base that leads to the ultimate limit state of a structure, presenting thus the lowest seismic resistance of the structure. Target acceleration is achieved by an iterative procedure, using a nonlinear numerical model of stability and load-bearing capacity of RC structures. A multimodal pushover analysis was performed for a linear combination of modes. The simplified target acceleration method is exemplified on two medium-rise RC frame structures. The influence of higher modes, particularly of the second one, has proven very significant. Validation of presented simplified target acceleration method was conducted through an incremental dynamic analysis. A comparison between the target acceleration obtained from the simplified target acceleration method and the failure peak ground acceleration obtained from the dynamic response of the structure exhibits very good agreement. The presented results demonstrate the ability of the simplified multimodal pushover target acceleration method to reliably assess the lowest seismic resistance of medium-rise RC structures.