Reliability of rigid hardening structures

For the simple structural system examined in the example, it is evident that the use of the approximate plastic elastic (hardening) model leads to a particularly simple systems reliability problem of the parallel type. This can be solved by noting that the elastic subsystem must, by definition, fail last, and that only rigid plastic limit states can be invoked earlier. Hence the problem reduces to an ideal plastic parallel system reliability problem, for which standard techniques, such as fosm, can be applied. Where the plastic subsystem involves more than one limit state, the intersection with the elastic hardening subsystem limit state may be less easy to find, and an equivalent linearization in fosm may be required. This is presently under investigation.