RELIABILITY OF STRUCTURAL SYSTEMS WITH GENERAL MEMBER BEHAVIOUR

For redundant structural systems, the limit state equations for given failure modes may be obtained by the so-called incremental loading method (ILM), in which members fail progressively as the load increments. In this report it is shown that ILM is capable of dealing with structural systems having multiple random loadings. A wider range of member behaviour other than plastic and brittle types previously considered by others is presented. For the special case of member behaviour in which the post-yield stiffness is zero, the so-called artificial load concept for use in the truncated enumeration method (TEM) has been shown previously to be simpler in application than ILM. It is shown herein that the results obtained from this approach agree with those from ILM. For multiple load cases it is demonstrated (but not proved) that the choice of load for incrementation is not important; the limit states obtained are invariant, provided that the utilization matrix in ILM is not singular. It is proposed that an economical system reliability analysis would be obtained by combining the truncated enumeration method (TEM) and ILM. Then for a wide range of member behaviour with the possibility of unloading of member capacity following failure, either partial or total, stochastically dominant modes of structural failure, are automatically generated. Several examples are given to illustrate the validity of the approach. (Author/TRRL)