Title: Bridge Spatial Displacement Monitoring with Fiber Optic Deformations Sensors
Author(s): S. Vurpillot, P. Kronenberg, and D. lnaudi
Publication: Symposium Paper
Appears on pages(s): 909-924
Keywords: bridge; deformation; sensor
Our laboratory fitted a highway bridge near Geneva (Switzerland) with more than 100 low-coherence fiber optic deformation sensors. The Versoix Bridge is a classical concrete bridge consisting of two parallel pre-stressed concrete beams supporting a 30 cm concrete deck and two overhangs. To enlarge the bridge, the beams were widened and the overhang extended. In order to increase the knowledge on the behaviour between the old and the new concrete, low-coherence fiber optic sensors were chosen in order to measure the displacements of the fresh concrete during the setting phase and to monitor its long term deformations. The aim is to retrieve the spatial displacements of the bridge in an earth-bound coordinate system by monitoring its internal deformations. The curvature of the bridge is measured locally at multiple locations along the bridge span by installing sensors at different distances from the neutral axis. By taking the double integral of the curvature and respecting the boundary conditions, it is then possible to retrieve the deformation of the bridge. The choice of the optimal emplacement of the sensors and the mathematical model required to interpreter the results are also presented.