Energy-based modal pushover procedure for asymmetric structures

Energy-based seismic evaluations of structures can give clear illustrations of seismic demands made upon structures. This paper presents a 3-dimensional energy-based modal pushover analysis (3D EMPA) method with equivalent three degree of freedom (ETDOF) system and equal-displacement rule. The lateral-rotational coupled effect on structures asymmetric in plan is considered using the energy-based modal pushover analysis (EMPA), which is more robust than the traditional Modal Pushover Analysis (MPA) procedure. The proposed procedure was validated against a nonlinear time history analysis of a 5-storey structure. The results show that the method is able to take higher mode effects into account and that the instability of capacity spectra will be avoided. The maximum deformation obtained from EMPA shows good agreement with a nonlinear time history analysis results of the original system. The proposed EMPA procedure appears to be reliable and effective for evaluating the seismic response of asymmetric-plan structures.