Abstract
In this study, the useful application of an instrumented structural health monitoring (SHM) system is proposed for the reliable seismic performance evaluation based on measured response data. A seismic fragility is chosen as a key index for probabilistic seismic performance assessment on an infrastructure. The seismic performance evaluation procedure consists of the following five main steps; (1) measuring ambient vibration of a bridge under general traveling vehicles; (2) identifying modal parameters including natural frequencies and mode shapes from the measured acceleration data by output-only modal identification method; (3) updating linear structural parameters in a preliminary finite element (FE) model using the identified modal parameters; (4) analyzing nonlinear response time histories of the structure using nonlinear seismic analysis program; and finally (5) evaluating the probabilistic seismic performance in terms of seismic fragility. In the present study, the seismic fragility curves are represented by a log-normal distribution function. An instrumented highway bridge is utilized to demonstrate the proposed evaluation procedure and it is found that the seismic fragility of a highway bridge can be reliably evaluated by combining the modal information obtained from the instrumented SHM system and FE model updating by using the information.
