A SIMULATION METHOD FOR TIME-DEPENDENT STRUCTURAL RELIABILITY

A one-dimensional simulation procedure is developed for use in estimat ing structural reliability in multi-dimensional load and resistance sp ace with the loads represented as stochastic process. The technique em ployed is based on the idea of using 'strips' of points parallel to ea ch other and sampled on the limit state hyperplanes. The 'local' outcr ossing rate and the zero time failure probability P(f)(0) associated w ith the narrow strips are derived using the conditional reliability in dex. When the domain boundary consists of a set of limit states, secon d order bounds are used to obtain a lower bound approximation of the o utcrossing rate and P(f)(0) associated with the union of a set of lamb da strips. It is shown by examples that for high reliability problems, lambda may be much less than the number of limit states without signi ficant loss of accuracy and with considerable saving in computation ti me. It was also found that the rate of convergence of the simulations is quite fast even without using importance sampling.