Dynamic curvature based monitoring in a highway overpass

With the growing challenge of aging infrastructure and the increasing cost for replacement and repair, structural health monitoring (SHM) offers an approach to address these challenges. It has been found in the literature that curvature and strain based methods may offer a more reliable approach to dynamic SHM compared to other methods such as acceleration and frequency based approaches. This research focuses on the application of a curvature based damage detection method, the normalized curvature ratio (NCR), to an in-service highway overpass. This method is widely applicable to beam like structures because it permits a structure to remain in-service, utilizes the service loads for monitoring, and is adaptable to a variety of sensor arrangements. Additionally, this research will focus on the use of long-gage fiber Bragg grating (FBG) sensors as they offer numerous benefits compared to other sensors currently available, such as low cost, multiplexing capabilities and the ability for both static and dynamic monitoring. Fiber optic sensors also allow for the instrumentation of large areas of a structure with long-gages sensors which helps enable global monitoring of the structure. Previous research applying this curvature based method in both small-scale laboratory testing and applied this method to a girder on an inservice highway overpass, demonstrating the feasibility of this method as a potential damage sensitive feature. This resaerch will focus on the applications of this method to girder 2 of the in-service highway overpass. Long term dynamic strain measurements from vibrations due to traffic loading on the structure have been measured through a series of FBG strain sensors instrumented on the structure. This research shows encouraging results and the potential for the NCR to be used as a simplistic metric for damage detection using FBG strain sensors.