Structural health monitoring of existing bridges in earthquake prone areas: Laboratory validation

Road infrastructures and particularly bridges can suffer structural damage due to earthquakes threatening the efficiency of the transportation network and the possibility to ensure prompt rescue operation. This particularly applies to existing bridges, most of which have been designed and built according to outdated codes. Structural Health Monitoring (SHM) systems can support the prompt assessment of bridges after seismic events. However, reliability of modal based damage detection currently depends on the accuracy of modal parameter estimates automatically obtained from the analysis of the operational response of the monitored structure, and on the capability of the measurement system to resolve low amplitude as well as strong motions, eventually associated to saturation of sensors. In the present paper, the performance of a modal-based SHM system for existing bridges in seismic areas is assessed by shaking table tests on a 1: 3 scale single span bridge representative of existing highway bridges built in the 60s in Italy. Results show that hidden damage can be identified on a remote basis, thus demonstrating the interesting applicative perspectives of modal based SHM for fast assessment of existing bridges in the early earthquake aftershock. The resilience to earthquake shaking of the SHM system has been also assessed. Finally, specific data processing procedures for earthquake response data are tested and compared with the results of laboratory measurements