Condition assessment of multispan masonry arch bridges

Abstract

A reliability-based condition assessment procedure of multispan masonry arch bridges is presented in this paper. Safety margins (limit state functions) are introduced for each arch of the bridge, with the authors considering axle load as assessment criterion. Two variables constitute the introduced safety margins: provisional axle load (PAL) which is estimated using MEXE methods, and actual axle load (AAL), which is estimated using weigh-in-motion measurements of the bridge. That both variables follow log normal distribution is assumed. Failure probabilities of each arch (estimated from statistical parameters of variables) then are combined to get the failure probability of the bridge using reliability bounds. The bridge reliability index is estimated from the failure probability. Bridge condition prediction is performed through comparison of the reliability index with its acceptable reliability index. Further, corresponding reliability index changes are discussed when the statistical parameters behave as interval numbers. The introduced assessment procedure is illustrated by a Sri Lankan four span brick masonry arch bridge.