Research On Bridge Jacking-up Optimization For Replacing The Bearing Of Concrete Continous Beam Bridge

Abstract:Due to the product quality, the construction precision, the increased traffic and the overloading, the bridge bearings would appear all sorts of diseases over a period of time. In order to use the bridge normally and safety, the injured bearing should be replaced in time.The "Lateral synchronization, longitudinal jacking-up by steps in different stages" method was used gradually, because it had the advantages of low occupancy personnel and less machinery equipment, facilitating the construction control, and not requiring interrupted traffic. To minimize the girder body’s stress and the construction workload, when this method was applied to multi-span concrete continuous beam, it was necessary to accurately analyse the reasonable combination of the maximum jacking-up and the location of jacking-up points. The key of this approaches how to determine the most reasonable combination, when the amount of jacking-up was large and there were many jacking points. Usually, some kinds of combinations were assumed according to the experience, then the different combinations can be calculated and adjusted. Finally, a satisfactory result would be selected as the last jacking-up scheme. However, the workload in the process of the calculation is too large, and the final scheme might not be the optimal result.Based on previous studies, this paper proposes the bearing jacking-up scheme by using the optimization method. The main research contents were as follows:(1) This article summarized the common diseases of the bearing, and introduced the developing situation of the bearing replacement technology in detail.(2) For the "Lateral synchronization, longitudinal jacking-up by steps in different stages" method, this paper established the jacking-up optimization mathematical model by choosing the lifting height of each pier as design variable, the stress of beam’s key section as constraint conditions, the least workload of jacking-up as the objective function.(3) The optimization problems were solved by the integer linear programming with interior point-branch and bound algorithm. The paper compiled optimization programs which were verified correctly and reliably by the standard examination questions.(4) Adopted the finite element calculation program for structural analysis in the process of optimization and used the influence matrix method to replace the structural reanalysis. The efficiency of optimization calculation has been greatly improved. It is proved that the optimization model is correct and efficient by two engineering examples.Overall, it proposed that the optimization thought can be used in the "Lateral synchronization, longitudinal jacking-up by steps in different stages" method for the first time.It could not only ensure the structure safety, but also the jacking-up workload would be the least as well.