Visualization system for bridge deformations under live load based on multipoint simultaneous measurements of displacement and rotational response using MEMS sensors

Abstract Displacement-induced fatigue accounts for most of the fatigue damage in steel bridges. In order to implement appropriate countermeasures against displacement-induced fatigue, it is important to understand bridge deformations under live load that cause stress concentration, and eventually lead to fatigue damage. Furthermore, knowledge of the positions of live load can shed light on the cause of bridge deformation. In the present study, a visualization system for bridge deformations is proposed. In the system, multipoint simultaneous measurements of displacement and rotational response are made by microelectromechanical systems (MEMS) sensors placed on an actual in-service bridge. The measured responses are input into a pre-made FEM model as the boundary conditions. MEMS sensors are suitable for multipoint simultaneous measurements of an in-service steel bridge, because they do not require a fixed reference point and can be attached by magnets on the painted surface of the bridge. Furthermore, the proposed system provided the positions of live load using the acceleration responses measured at the vertical stiffener on both longitudinal edges of the main girder. Implementation of the proposed system in an actual in-service bridge revealed the relationship between the bridge deformations that leads to the stress concentration and the positions of traveling vehicles.