Modified Modal Pushover Design for Asymmetric-Plan RC Shear-Wall Structures

Abstract

The goal of this research is to provide a new method for designing reinforced concrete wall structures with a one-way asymmetric plan. This presented method is called the modified modal pushover design method (MMPD), which uses assumptions of modified modal pushover analysis (MMPA) for estimating the responses of structures. In summary, the arbitrary distribution of walls’ reinforcements at the beginning of MMPD design steps is modified so that a structure is limited to its selected limit state when analyzed by the MMPA method by knowing that walls’ stiffness is proportional to their corresponding strength. An appropriate hysteretic model (PIVOT model) is selected for the first-mode nonlinear SDOF system so that it estimates the peak and time history displacement response of the roof accurately. Three 8-storey buildings are designed for two different distributions of reinforcement areas to assess their effects on NRHA demands of each story. Higher mode contributions in responses of all structures are calculated by the elastic jagged response spectrum; mean-matched smoothed displacement response spectrum ± standard deviation curve is also used to compare stories’ shear and torsional demands estimated by these two response spectra. The results have shown the accuracy of the MMPD method in calculating the strength and stiffness of seismic-resisting walls.