Report - PEER - University of California, Berkeley

POST-EARTHQUAKE FUNCTION OF HIGHWAY OVERPASS BRIDGESKevin MACKIE 1 and Božidar STOJADINOVIĆ 2ABSTRACTBridges are a crucial part of the transportation network in a region struck by an earthquake.Whether the bridge has collapsed or not determines if a road is passable. Ability of a bridge tocarry traffic load after an earthquake determines the weight of trucks that can cross it and thespeed at which such traffic may move. Extent of structural damage in bridges as structuralsystems and bridge components determines the cost and the time required to repair them.Today, post-earthquake bridge evaluation is qualitative and empirical rather than quantitative.The goal of our research is to provide an engineering basis for quick and reliable evaluation ofthe ability of a typical highway overpass bridge to function after an earthquake.The PEER probabilistic performance-based evaluation approach provides the frameworkfor bridge function evaluation. Three limit states, repair cost, traffic function, and collapse areaddressed. An analytical study was performed that links engineering demand parameters for afamily of typical U.S. highway overpass bridges to ground motion intensity measures. ThePEER structural element performance database and reliability analysis tools were used to linkengineering demand measures to damage measures. Finally, a number of decision variableswere developed that describe the considered limit states in terms of measures of induceddamage. This paper presents the analytical models involved in bridge post-earthquake functionevaluation, the decision variables and their correlation to the considered limit states, and thefragility curves that represent the probability of exceeding a given limit state in a high seismicrisk zone in the U.S.Keywords: Performance-based earthquake engineering; Fragility; Decision variables;Damage limit state.1. INTRODUCTIONCan we get there? How quickly? How heavy a load can be transported? How muchwill it take to repair any damage? How long will that take? These are the questionsposed by emergency managers, recovery planners and structural engineers after anearthquake. The answers are in the state of highway infrastructure in a region struck1 Doctoral Candidate, Dept. of Civil and Env. Engineering, University of California, Berkeley, Berkeley,CA 94720-1710, mackie@ce.berkeley.edu2 Associate Professor, Dept. of Civil and Env. Engineering, University of California, Berkeley, Berkeley,CA 94720-1710, boza@ce.berkeley.edu53