The Temperature Gradient Effect Of Lightweight Composite Beam On Super-span Suspension Bridges

With the development of bridge structure and the study of material, composite bridges have been widely used. Composite bridges can make full use of the superior tensile properties of steel and the good compression performance of concrete. In the traditional composite bridge structures, the concrete deck is thick, with the increase of bridge spans, the weight of structure gets larger, which leads to a limit of the development of super-span bridge. Using composite bridges on continuous girder bridge may cause large tensile stress in the upper part of the concrete, even make concrete cracks, so as to affect the durability of the bridge structure.It is put forward a research on the use of lightweight composite beam on super-span suspension bridge in this paper. The main structure of light-weighted composite bridge is orthotropic steel bridge panel which is connected with UHPC(Ultra-High Performance Concrete) by shear connector. UHPC has the advantages of high strength, good durability, less shrinkage and creep and stable volume. It can significantly reduce the weight of structure, and improve the acrossing ability of bridge when it’s used with orthotropic steel bridge panel. This light-weighted composite bridge not only improves the overall mechanical performance, but also increases the local mechanical performance under vehicle wheel load. Based on the super-span suspension bridge across the Qiongzhou straits, the mainly following research work has beed made in this paper:(1)The temperature gradient simulation of light-weighted composite beam structure: Based on the theory of solar radiation and the heat transfer between the structure and the external environment, establish a third type of boundary conditions of light-weighted composite beam under sunshine, propose a appropriate temperature gradient of light-weight composite beams. Also analyse the the influence of asphalt pavement layer on the temperature gradient, and finally analyses the main parameters affecting the temperature gradient.(2)The calculation of cable shape on super-span suspension bridge: Combined with specific engineering, the shape and internal force of main cable have been calculated respectively by adopting analytical method and finite element analysis, when the constraciton of the bridge finished. It points using the finite element calculation is feasible in the static calculation of super-span suspension bridge by comparing results of the two calculation methods.(3)Static calculation of super-span suspension bridge: Through the finite element software, adopt the linear second-order method and nonlinear finite element to calculate the static performance of the suspension bridge, comparison of the two calculation results show that linear second-order method is feasible.(4)Comparison of ligh-weighted composite beam with the traditional steel box girder: calculate and compare mechanics performance and economic cost of the two plans. Results indicate ligh-weighted composite beam is more reasonably than traditional steel box girder on super span suspension bridge.