Reliability-based structural design

This paper presents the use of state-of-the-art reliability techniques to develop efficient structural design guidelines for civil engineering structures in a manner that includes overall structural system effects. Probabilistic design is done by explicitly accounting for the uncertainties in the different variables and their influence on structural performance. This approach has been used to develop a set of load and resistance factors instead of just a single safety factor to address all the uncertainties. However, the reliabilities of the individual components, when placed in the overall configuration, may not remain the same as when the components are considered separately. Therefore, this paper proposes that the reliability of the structure be explicitly satisfied at the component level as well as at the system level during design. Two important considerations are addressed in this regard: (i) the influence of system effects on the element reliability, and (ii) formulation of component design to ensure overall system reliability. As a result, system factors are developed for inclusion in structural design.