Dynamic capacity curve and its application to the seismic evaluation of structures

This paper presents a simplified procedure for the seismic evaluation of structures based on the dynamic capacity curve; and its validity as a structural property associated with seismic demands. The proposed procedure calculates the performance of a structure subjected to seismic demands from a uniform hazard spectrum through an approximation of the dynamic capacity curve constructed from modal spectral analysis associated with increasing intensity demands. To account for stiffness reduction and energy dissipation due to hysteresis, a single-degree-of-freedom oscillator with the characteristics of the fundamental mode is analysed. The approximation of the dynamic capacity curve obtained from the proposed procedure is validated by comparing it with that obtained from nonlinear time-history analysis under increasing intensity demands for two reinforced concrete structures: a 12-storey plane frame irregular in elevation and a continuous viaduct-type bridge.