Redundancy and robustness of structures: A retrospective

摘要

Issues related to structural redundancy and robustness have gained increased importance after a number of recent major collapses due to man-made or natural hazards. As a result, several recent and on-going studies have focused on determining the failure mechanisms in typical structural systems and are making recommendations to improve the overall system safety of civil structures including buildings and bridges. Yet, despite major advances in developing methodologies for the structural analysis of cascading failures and in understanding the behavior of different types of systems under suddenly applied extreme loads, a main issue related to defining objective measures of redundancy and quantifying the levels of redundancy that exist in structural systems remains vastly unresolved. This paper revisits some of the work done by the authors and their colleagues on the quantification of system redundancy and reviews previously made proposals for including system redundancy and robustness during the structural design and safety assessment of structural systems. These proposals, which are based on system reliability principles, consider structural system safety, system redundancy and system robustness in comparison to member safety, and account for the uncertainties associated with determining member and system strengths as well as future loads in a consistent and rational manner.