12.07.2015 Views

Report - PEER - University of California, Berkeley

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AN ANALYSIS ON THE SEISMIC PERFORMANCE LEVELS OF BRIDGESKazuhiko KAWASHIMA 1ABSTRACTThis paper presents an analysis on the seismic performance criteria and levels <strong>of</strong> bridges basedon a questionnaire survey to 100 civil engineers. Analysis is presented for design criteria,period and cost <strong>of</strong> repair, expectation and problems, and analytical tools in the performancebasedseismic design.Keywords: Performance-based design; Seismic design; Bridges; Performance criteria;Analytical tools; Seismic damage.INTRODUCTIONIn seismic design <strong>of</strong> bridges, it is important to have clear seismic performance criteria.The basic concept <strong>of</strong> seismic design philosophy and performance criteria is more orless similar among the current codes worldwide. For small-to-moderate earthquakesbridges should be resisted within the elastic range <strong>of</strong> the structural componentswithout significant damage, and bridges exposed to shaking from large earthquakesshould not cause collapse. The performance requirements depend on the importance<strong>of</strong> bridges.For example, Table 1 shows the performance criteria and performance matrix <strong>of</strong>bridges in Japan (JRA 2002). Function evaluation ground motions and safetyevaluation ground motions are considered under the 2 level seismic design. Middlefieldground motions generated by earthquakes with magnitude <strong>of</strong> about 8 (Type-Iground motions) and near-field ground motions generated by earthquakes withmagnitude <strong>of</strong> about 7 (Type-II ground motions) are used. The seismic performance isclassified in terms <strong>of</strong> safety, function and reparability.However the expression in the performance criteria and goals is general andvague. For example, what does “maintain safety for collapse” mean? Is it allowed thatbridges cannot be repaired after an earthquake if only collapse can be avoided, orshould damage be within a certain level so that bridges can be repaired? What “retainfunction in a short time after an earthquake” means? How shortly the damaged bridgeshould be repaired?1 Pr<strong>of</strong>essor, Department <strong>of</strong> Civil Engineering, Tokyo Inst. <strong>of</strong> Technology, Tokyo, Japan, Email:kawasima@cv.titech.ac.jp77

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