Back analysis for earthquake damaged bridges. Part I: General procedure

This paper and its companion (Sebastiani et al., 2012) present a method of back analysis for the interpretation of earthquake damage patterns of bridges. The a posteriori damage evaluation is based on a number of finite element analyses carried out with the aim of bounding the structural and geotechnical configurations. This first part presents the methodological aspects of the procedure, comprised of a series of investigations and modeling steps. Regarding the investigations, they consist in: i) geological and geotechnical surveys to evaluate soil properties, ii) studies to characterize the occurred ground motion, iii) structural investigations to establish the structural conditions of the bridge before and after the occurred earthquake. Afterwards, a set of models to evaluate the local site effects, the soil-structure interaction and the structural behavior by means of nonlinear time history analysis is employed. All necessary steps to reproduce the damage scenario are discussed, with flowcharts representing the various analysis phases. The methodology does not only aim at identifying the causes of damage, but also at bounding the occurred damage within the range of scenarios corresponding to the problem uncertainties. To this end, different structural, seismic and geo-technical models are compared in order to evaluate the influence of uncertainties on the results. © 2012 Taylor & Francis Group.