Long-term performance of structural health monitoring system in bridges

Despite the fact that structural health monitoring systems (SHMS) are generally intended for long-term service, rare attention has been paid to the long-term performance of sensor systems. It has been observed that life durations of many installed sensors may not be as long as the service life of bridges, which makes proper inspection, maintenance or even complete replacement of sensor systems necessary during lifetime of bridge structures. Therefore a rational optimal design approach of sensor systems needs to properly take into account their long-term performance including lifetime, life-cycle reliability and maintenance period. The traditional design approaches solely based on initial performance and cost may be compromised by neglecting these factors. In light of this limitation, this paper studies the "health" of SHMS on bridges. A performance index is developed to assess the functionality of sensor systems, and the time-variant performance is then studied in a probabilistic framework.