DEFLECTION ESTIMATION OF A FULL SCALE PSC GIRDER USING LONG-GAUGE FIBER OPTIC SENSORS

초록

This paper investigates the applicability of long-gauge fiber optic sensors (FOS) to prestressed concrete structures. A main motivation is the desire to monitor the deflection of the railway bridges without intervenes of the signal intensity fluctuations. A 25 m long and 1.8 m deep bulb-tee prestressed concrete (PSC) girder was compositely fabricated with a 2 m wide and 22 cm thick reinforced concrete deck. Two pairs of 3 m long-gauge sensors were attached to the prestressed concrete girder with parallel topology. Using the geometric relationship between curvature and vertical deflection in a simple beam and the quadratic regression of curvatures at the discrete point, it is possible to extrapolate the deflection curve of the girder. The estimated deflection measured by the developed method is compared with the results using conventional strain gauges and LVDTs. It has been demonstrated that long-gauge fiber optic sensors provide excellent agreement with conventional sensors.