ESTIMATING THERMAL INERTIA AND TEMPERATURE DISTRIBUTION CONSISTENT WITH MONITORED DATA FROM A RAILWAY BRIDGE

This paper proposes a sequence of analyses allowing the designer to quantify the changes in the structural response due to the temperature variation. This is illustrated for a case study on a railway bridge. The SHM (Structural Health Monitoring) system installed on the bridge consists of Fiber Bragg Grating (FBG) sensors. A numerical model of the bridge was created. The plot of the daily variation of the vertical displacement of a node, when numerically computed for a temperature field interpolating the readings of the temperature sensors, shows a curve similar to the recorded history plot, but the latter one is delayed. This delay is due to both the thermal inertia of the deck, the reinforced concrete of the superstructure, and the actual temperature distribution across and along the deck. Thus, a refined study of the temperature time histories was conducted by a suitable thermo-mechanical model driven by the temperatures measured at the sensor locations. The obtained field of temperature is then used as input for a stress-strain analysis. The resulting displacements are eventually compared with the measured values. Using a first set of data, the numerical model parameters are calibrated, while a second set of data is used for a validation of the whole procedure.