Application of a Web-enabled real-time structural health monitoring system for civilinfrastructure systems

Abstract

The system architecture of a novel structural health monitoring system that isoptimized for the continuous real-time monitoring of dispersed civil infrastructures ispresented. The monitoring system is based on a highly efficient multithreaded softwaredesign that allows the system to acquire data from a large number of channels,monitor and condition this data, and distribute it, in real time, over the Internet tomultiple remote locations. Bandwidth and latency issues that impact the operationof monitoring systems are discussed. The application of the monitoring systemunder discussion to a long span, flexible bridge in the metropolitan Los Angelesregion is described. The bridge had previously been instrumented with 26 strongmotion accelerometers. Sample ‘quick analysis’ results continuously provided by themonitoring system are presented and interpreted. System identification results,obtained through off-line batch processing, are presented for a data set from arecent earthquake that automatically triggered the recording capability of thesystem. It is shown that, using a time domain system identification approach,the bridge stiffness and damping matrices can be identified from the earthquakedata set and subsequently used to determine the bridge modal properties, suchas frequencies and damping ratios. In this approach the bridge is modeled as amulti-input/multi-output system with order compatible with the number of availablesensors. Implementation issues requiring further investigation are presented and discussed.