Separation Test Method for Bridge Bearing Based on Displacement

In order to overcome the shortcomings of the traditional test method for bearing separation,such as difficulties in the installation of sensors and large measuring errors,the displacement method for judge the existance of the bridge bearing separation was proposed based on the different regularities of bridge deformation before and after the seperation,the proposed method according to the theoretical reaction-measured displacement curve and combined with the theoretical displacemnt curve.Laboratory experiments and in-situ load tests were performed to verify the effectiveness of the displacement method.The results from an experiment on a three-span continuous beam show that(1) the values before and after separation can be fitted by two lines that differ significantly in slope;(2) when the separation occurs,a turning point appears;(3) the slope of the curve before and after the turning point can vary as much as eightfold,the displacement method not only can judge the existance of the bridge bearing separation,but also can give the separation load and the elastic coefficient of the bearing;(4) together with the theoretical results,the displacement method can distinguish the separation appeared before the test,in the test or not appeared at all.The result from a load test on a four-span continuous steel box girder bridge shows that the proposed method is feasible.