The evaluation of bridges by distributed FBG sensors

A distributed sensing system developed by authors for flexural structure using strain measurements from long-gage fiber Bragg grating (FBG) sensors for structural health monitoring (SHM) was introduced in this paper. By utilizing the sensing system, the following features of bridge can be evaluated: (1) strain distribution along the bridge; (2) bridge deflection distribution; (3) dynamic characteristics of bridge such as frequency and modal shape; (4) load level and (5) damage detection using modal macro-strain vector constructed by the strain measurement of all FBG sensors. To validate the effectiveness of the developed FBG sensing system, a series of field investigations on a reinforcement concrete (RC) bridge, a railway bridge and a pre-stressed concrete (PC) bridge were performed. The field observations showed good agreement between the results obtained from the sensing system and finite element method (FEM) analysis. This demonstrates that the sensing system could provide a multifunctional approach for SHM in the intelligent infrastructure.