Redundancy of structural systems with and without maintenance: An approach based on lifetime functions

The lifetime reliability of existing structures may be quantified by lifetime functions. Redundancy is an additional type of structural performance indicator that is defined as a measure of warning available prior to system collapse. Lifetime functions provide a basis on which lifetime redundancy can be evaluated and its quantification can be formulated. The objective of this paper is to present a novel approach for the evaluation of the lifetime redundancy of structural systems. Measures of lifetime redundancy based on lifetime functions are investigated. The effects of maintenance on lifetime functions and redundancy are also presented. Furthermore, the lifetime redundancy is incorporated in a maintenance optimization algorithm. This optimization algorithm is illustrated on an existing highway bridge.