Implementation of directional simulation to estimate outcrossing rates in time-variant reliability analysis of structures

Time-dependent reliability analysis of structures by the use of an outcrossing approach normally requires the so-called outcrossing rate to be estimated. A variety of methods has been recorded in the literature to evaluate this rate both for continues and discrete processes. Despite the availability of these methods, still more general and at the same time less sophisticated approaches are desired. In this paper, attempt is made to use the basic idea of "parallel system reliability formulation" to calculate the outcrossing rate for circumstances where the processes are continuous. These calculations are carried out by directional simulation. It is shown that this approach is simple to implement and may be used for the cases where the problem involves nonstationary processes and also for the cases where several limit state functions may have to be considered.