Formulations of Structural System Reliability

Abstract

Two formulations are developed for the determination of the reliability of general redundant structural systems. One is the failure mode approach, which is based on ways in which a structure may fail. The other is the stable configuration approach, which is based on the possible configurations in which a structure may carry an applied load. Conceptually, the stable configuration approach has the advantage over the failure mode approach in that neglecting possible configurations will be conservative, whereas neglecting potential failure modes will be unconservative. For a class of structures, in which the load effects on a surviving element never decrease with the failure of other elements (consistent redistribution), simplified formulations are obtained. Such simplifications for this type of structure result from the fact that the exact sequence in which the elements will fail is irrelevant. Results of the simplified formulations are conservative for structures in which the load effect on a member may be reduced following the failure of another member.