Multi-channel random decrement smart sensing system for concrete bridge girders damage location identification

The concept has been used before for steel and metal structure. However, the concrete material is a nonlinear elasto-plastic damaged material with unique qualities of cracking, tension softening, shear degradation and tension stiffening effects. The emphasis for the steel beam monitoring is focused on the change in the natural frequency; however, the emphasis for the concrete beam monitoring is focused on the change in the Random Decrement Damping (RDD) between the intact and damaged case. The change in RDD is more evident for concrete beams due the rapid change in stiffness due to cracking and the propagation of cracking due to loading. The focus in this work is to assess the applicability of using MCRD with FBG arrays for monitoring reinforced concrete (RC) girders based on experimental testing. For validating the feasibility of the proposed approach, a laboratory investigation has been performed on a main and secondary girder to identify the suitability of using FBG sensors on RC girders to detect the damage and locate it. The results of the investigation showed that MCRD using FBG sensors has the potential to detect the damage location that could be implemented effectively in bridge monitoring strategies.