Safety Analysis of Statically Indeterminate Trusses 670615

The reliability analysis is formulated for a certain type of statically indeterminate structure with random resistance and subjected to a random load. Specifically, this paper studies the effect of stress redistribution on the reliability of the structural system due to the failure of certain redundant members in an m-member plane truss. In addition, the probabilities of complete survival for structures with different degrees of redundancy were compared on the basis of equal volume of materials used.

Numerical examples indicate that (a), for designs with each member carrying the same proportion of load, the failure of one member in a statically indeterminate structure is not necessarily more likely to cause the failure of the whole structural system, (b), for designs with equal area in each member, the probabilities of complete-survival of statically indeterminate trusses (with the exception of the three-member truss) are greater than those of the statically determinate truss with the same volume, and (c), for the type of structures investigated the statically indeterminate trusses should be designed so that each member has an equal cross-sectional area from the viewpoint of reliability. A third example shows that the effect of the number of members on the probabilities of complete-survival pmm for a parachute-like, three-dimensional structure becomes less pronounced at larger values of volume.