Application of Structural Health Monitoring System for Reliable Seismic Performance Evaluation of Infrastructures

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.