Probability Density Evolution of a Nonlinear Concrete Gravity Dam Subjected to Nonstationary Seismic Ground Motion

Abstract

To simulate fully nonstationary earthquake ground motion, an improved generalized evolutionary spectrum model derived from a counterpart of stationary seismic processes is proposed in the present paper. Through integrating the proposed generalized evolutionary spectrum model and updated spectral representation method (U-SRM), a renewed simulation scheme is adopted to represent fully nonstationary seismic accelerations. The complete set of representative samples of earthquake ground motion with assigned probabilities can thus be readily generated. For the purpose of comprehensively evaluating the dynamic reliability of a concrete gravity dam structure, three relative displacement angles are suggested. Using the renewed simulation scheme combined with the probability density evolution method (PDEM), the nonlinear stochastic responses and dynamic reliability analysis for a randomly base-excited concrete gravity dam are examined. Numerical results reveal the physical mechanism of nonlinear seismic responses of concrete gravity dams. It thus indicates that the renewed scheme integrating the proposed generalized evolutionary spectrum model and U-SRM accommodates a more logical indicator for the seismic design of concrete gravity dams than the deterministic seismic design currently used in practice with recorded seismic accelerations.