Optimal Design Of Prestressing Tendons In Long-span PC Continuous Rigid Frame Bridges

With the rapid transit development of China's highway, more large span bridge was needed to span great rivers and bays, PC continuous rigid frame bridge emerged as the times require and was developed fleetly in recent years. In the optimal design of PC continuous rigid frame bridge, the optimization of three-dimensional prestressing tendoms is a urgent problem needed to solved. The prestressed design of PC continuous rigid frame bridge is an important component of the structural design to the main bridge. If the design of prestressed is appropriate, Not only increased the mechanical behavior substantially and applicated the concrete fully, but also reduced the structural self greatly, thus saved a lot of steel.Based on the Longtanhe Bridge of Hurong national highway in the west of Hubei province, this thesis focuses on the optimization of three-dimensional prestress of the PC continuous rigid frame bridge to study. The main research work is summarized as follows:(1) First, the existing research work on the optimization of pressing tendon had been introduced. Then, the deficiencies Department of the pressing tendons's Design was discussed.(2)The paper gives a method of optimized design of the prestressing tendons in continuous rigid-frame bridge which is constructed with cantilever, which based on the minimum bending energy method. The first step is selecting the construction control section and defining the object functions with the minimum bending energy of the discrete section, and the restriction condition is the section stress of each construction phase and the operational phase; the second step is using the Optimization Toolbox of Matlab to optimize the prestressing tendons.(3) Based on the results of the above optimization, the paper Combine BP neural networks and genetic algorithms to optimizate the angle and the curves of the longitudinal prestressing tendons and the spacing of the vertical prestressing tendons.(4) Taking Longtanhe Bridge of west HuRong national highway for example, based on the finite element procedure, which was programmed by APDL language, the interaction of the transverse prestressing tendons and the longitudinal prestressing tendons was studied, which geted the influence line of interactioncoefficient; and the shear lag effect of the prestressing was studied.