Time-variant reliability analysis of hysteretic SDOF systems with uncertain parameters and subjected to stochastic loading

The problem of the time-variant reliability/safety analysis of nonlinear hysteretic structural systems with system parameter uncertainty and subjected to stochastic dynamic loading is the object of this paper. A computational method based on the first-order reliability method, FORM, to obtain an upper bound of the probability of the system exiting or out-crossing a safe domain within a given time interval is applied to the Bouc-Wen single-degree-of-freedom (SDOF) hysteretic oscillator subjected to base excitation. An algorithm to compute the exact-gradient of the numerical response of the oscillator with respect to both loading and system parameters is developed and used as part of the time-variant reliability method. The:effects and relative importance of loading stochasticity and system parameter uncertainty are investigated.: Valuable insight into the behavior of the SDOF system under conditions of loading and system uncertainty is provided by the design point. Upper bound time-variant failure probabilities obtained for both the deterministic and uncertain Bouc-Wen oscillators are verified through Monte Carlo simulation.