Structural Seismic Performance Evaluation of Highway Bridges Based on Vibration Measurements

This paper represents the first effort in seismic fragility analysis of a structure using a structural analysis model developed on the basis of measured vibration data. An instrumented highway bridge is used to demonstrate the analysis procedure involving measuring ambient vibration, identifying modal parameters from the measured data, updating a preliminary FE model (obtained from structural design drawings) with the measured modal parameters, analyzing nonlinear response time histories of the structure under earthquake excitations, and finally developing fragility curves. The seismic fragility of a highway bridge is more reliably evaluated by utilizing the updated structural model. NOMENCLATURE J : objective function i w : weighting factor i f : natural frequency of i -th mode i φ : mode shape of i -th mode A : sectional area I : moment of inertia j c : correction coefficient for structural parameters θ : rotational displacement y θ : rotational displacement at yield j F : fragility curve