VERTICAL DEFLECTION OF A PRESTRESSED CONCRETE BRIDGE OBTAINED USING DEFORMATION SENSORS AND INCLINOMETER MEASUREMENTS

The serviceability of a bridge is generally analyzed by a comparison b etween the vertical deflections expected by the engineer and those mea sured during a load test or in the long term The existing methods do n ot allow the determination of the vertical displacements from the meas urements carried out by a network of deformation sensors placed inside the bridge. The mathematical model presented here allows the determin ation of the displacement field from internal horizontal deformation m easurements and helps in the design of the required sensor network. Th is model was tested on an experimental model and on the Lutrive Highwa y Bridge (Switzerland) by comparing the changes in vertical displaceme nts under daily temperature variations obtained with the proposed meth od, with those measured directly using an absolute hydrostatic levelin g system. Fiber optic deformation sensors and electrical inclinometers were used to carry out the measurements. With this deformation monito ring system, featuring a precision of 10 mu m on I m long deformation sensors, it is possible to retrieve the vertical displacement field of a beam with a global error less than 8 percent.