IFEM method for distributed monitoring of cable forces in cable-stayed bridges

The method proposed in this article pertains to developing a technique for structural health monitoring of cable-stayed bridges based on the inverse finite element method (iFEM). This approach is built on distributed monitoring of strains by using a Brillouin scattering-based distributed optical fiber sensor. Using this method, both the deflections and changes in cable forces are computed to assess the structural health of bridges. In contrast to the existing distributed strain-based techniques, the computation of cable forces does not require prior knowledge of loads and their locations. This provides the opportunity for use under operational conditions of the bridge, where the bridge is subjected to moving vehicular loads. The capability of the proposed technique was evaluated in laboratory experiments by a scaled model of a cable-stayed bridge. The experiments involved static and dynamic loads and the acquisition of distributed strains by a PPP-BOTDA optical fiber interrogation unit. Other sensor types, such as LVDT and FBG sensors, were employed in the experiments to validate the results of the proposed computational approach. In addition, the differences between the proposed approach and previous techniques are compared in terms of the computational approach, their attributes, and percentage errors in the computation of cable force variations.