AbstractThe capacity deterioration of structures over time may impair their seismic structural reliability significantly, and, thus, they should be taken into account when assessing their seismic performance. In this study, a closed-form solution was proposed for time-dependent seismic reliability analysis of deteriorating structures. The capacity deterioration on the temporal scale was captured by the generalized capacity and deterioration function, and the Fréchet distribution was used to describe the probabilistic behavior of the peak ground acceleration. The deterioration of structural seismic capacity was modeled by a power function of time, and, thus, it was a nonlinear process if the exponent was other than 1. For a representative case, with some minor assumptions about the probability models of the deterioration process and of the seismic hazard, the proposed reliability analysis method was further simplified without the computation of integrals, which is beneficial for use in practical engineering. A numerical example was presented to demonstrate the accuracy and applicability of the proposed reliability analysis method. Future works will include the extension of the capacity deterioration model to more general forms for use in seismic structural reliability assessment through benchmark studies of real-world aging structures.