Research And Applying Technique Of Strengthening Old Arch Bridge With Jacking Force

With the merits of full use of the materials, saving steel bar and the cement, structure simple, big bearing potential, and costs few, the masonry arch-bridge is widely used in China. In recent years, along with the promotion of load rank, services ability of the arch bridge in the maintain area is severely weakened due to the various diseases occurs in operating and need to be maintained. Therefore, it is urgent to study on masonry arch-bridge's reinforcement. Some old arch bridges are lack of bearing capacity, and its design load needs to be improved. As a result, the new Reinforcement Method with Steel truss arch ring pushing up old arch ring is proposed according to the virtual reinforced concrete arch bridge near the JinChuan group railway special line in GanSu Province. The simulation was carried out by using the finite element analysis software MIDAS/Civil. Also the contrast between the pre and post bridge on static and dynamic characteristics was investigate.The purpose of the strengthening method of incremental launching method is to make the new arch ring bear the load which the old can't bear. By compared to the traditional strengthening method, the new method proposed can unload the old arch ring, partially recover the crack,and reserve some bearing capacity. Two arch rings can work well together by shift load on old arch to the new one. In the process of the strengthening, the reinforcement effect can be controlled to reach the target by changing the jacking force.The study was concentrated on two aspects:1) Based on the reinforcement methods of common arch bridges, the new Reinforcement Method was proposed with the mechanic performance of the masonry arch-bridge. And some discussion was made on the rationality of the method in theory and simulation. By comparing push vertical and push radial in theory and simulation, drew the conclusion that vertical jacking method was better.2) Cabined with reinforcement practice of a virtual arch, a numerical model was established using Midas program. The feasibility was verified valid by comparing with static and dynamic characteristics pre and post.The conclusion showed that the stress and deflection was decreased obviously when the old arch bridge was reinforced, vertical rigidity was improved, and dynamic response was decreased. Proved the feasibility of the method. It can be a reference for similar arch bridges.