Ductility spectra of reinforced concrete structures subjected to far-field seismic excitations

Abstract

This paper calculates the nonlinear ductility ratio spectra of low-to medium-rise RC structures subjected to simulated earthquake ground excitations. Two nonlinear structural models are used. One represents RC structural failure primarily by shear and the other represents the failure primarily by flexural tension and compression. Four types of earthquake ground motions are simulated for the calculation. They represent motions at a rock and a soft soil site caused by an earthquake of Richter magnitude 8 and epicentral distance 300 km. For each type of motion, 20 time histories are simulated for the structural response analysis. The mean response spectra of ductility ratios and their coefficients of variation for the two structural models subjected to each type of motion are calculated by using the 20 simulated time histories. The probability functions of the ductility ratios are formulated by using the mean values and coefficients of variation. These functions are used as preliminary estimators of failure probabilities of RC structures. The results presented can be used to check the safety probability of low to medium rise RC structures under earthquake excitations.