Energy Demand and Damage Assessment of a Multi-Story Frame Based on Static Pushover Analysis

Static pushover method has become a common tool for performance based seismic design and evaluation of structures. In this paper, an energy based method has been developed as a design and evaluation tool to assess the energy demand and cumulative damage using the pushover analysis. The app roach is based on the relationships between the elastic input energy, hysteretic energy, and the energy under the monotonic response, pushover curve. Single degree-of-freedom (SDOF) systems were first analyzed under selected ground motions to obtain the key relationships. The method was applied to a low-rise steel moment frame to predict the energy demand and cumulative damage due to ground motions. A nonlinear pushover analysis was first conducted to obtain the monotonic response curve and distribution of hysteretic energy along the height of the frame. The input energy from the ground motions was used to determine the target deformation and hysteretic energy demand. Finally, cumulative damage was assessed based on the Park-Ang Damage Index. The deformation, energy demand, and cumulative damage predicted based on the pushover analysis were compared with those obtained from time history analysis results. The accuracy and limitations of the method are presented and discussed.