Damage Identification of Simply-Supported Beam Bridge Based on Deflection Influence Line

In order to extend the service life of the bridge and reduce the occurrence of catastrophic accidents, it is necessary to monitor and identify the damaged parts of the bridge in time. In this paper, the author firstly proposes a basic theory of deflection influence line, then analyzes the calculation basis and proposes a method of deflection influence line of simple supported structure. Finally, according to displacement-time curve of simply-supported beam structure under different load-moving speed can be obtained by using MIDAS, the mid span, damage degree and load-moving speed of structure model can be set to carry out the simulation calculation. The results show that: when the load moving speed is 10km/h, 30km/h, 60km/h and 100km/h, the influence line of deflection difference has no obvious change pattern, and there are different peak values, which cannot be used for damage identification. Under the static load condition, the influence lines of deflection difference at 1/2L position, 3/4L position and end part at 10% and 25% damage degree basically show linear change, while the deflection difference value at 1/2L position appears peak value, and the maximum deflection difference value at different damage positions shows nonlinear change. It indicates that the damage degree can be judged according to the deflection differences at the damage positions identified above.