The Fiber Model Applied To Concrete Filled Steel Tube Arch Bridge

The concrete-filled steel tubular( CSFT) is superior to other structures in high bearing capacity,technology and economy. Because of these advantages, it has been adopted in industry factory and high rise buildings widely. Arch bridge has been paid more attention in our country since ancient time,for its notable architectural effect, high load-bearing capacity, low construction cost, and good endurance. Concrete-Filled steel tubular(CFST) have been adopted more and more in bridges, because of the improvement of the strength of material and convenience of erection. Therefore the domestic and international scholars have carried on by many researches on mechanics performance and design method of the concrete-filled steel tubular structures. It is possible to engender some defects in the internal concrete and the cementation deviating between steel and concrete after pouring concrete. CFST column which carries the main load is mostly applied in construction structure. The structural stability and the mechanical properties of components would be reduced due to the defects. Therefore, it is essential to research the effect of different material parameters and the magnitude of lateral loads to the reduction of bearing capacity .Opensees (Open System for Earthquake Engineering Simulation) is a computational platform developed by University of California at Berkeley. Its key feature is open source and framework. Users can apply and develop it by the Internet. On the basic of Opensees , the influence of member stability is analyzed, The main contents are listed as follows:1. The concept and the calculations method of the fiber model are introduced , theoretical analysis verify the fiber method can be used in the calculation of concrete fillde steel tubular arches.2. On the basic of the Opensees computational platform,analysed the capacity of a concrete filled steel tubular arches, its numerical result is compared with that obtained by the previous experimental method .Primitive results verify the feasibility of the fiber method. 3. Calculated a concrete filled steel tubular arches based on the Opensees computational platform ,the effect of different material parameters and the magnitude of lateral loads was analysed ,the rule of bearing capacity reduction is obtained.4. Disengaging of steel tube confined concrete in arch bridges was analysed based on the Opensees computational platform, the effect of disengaging angle ,disengaging axial length and radial thickness were analysed , systematically summarized the effect of each factor. Obtained concrete filled steel tubular arches disengaging reduction factor, hoping that it may furnish reference for similar project.5. Under the background of zhijinghe super large bridge, the fiber model was applied in engineering calculation, its numerical result is compared with that obtained by the traditional FEM method, laid a foundation for the further engineering application of the fiber model.