Initial Stress On The Bearing Capacity Of Long-span Cfst Arch Bridge Stability

With the development of new methods of structural analysis technique and electronic technology, the advance of skills of model test, the emergence of new types of high strength and quality of rolled steel, as well as the more and more perfection of construction technology and design theories, arch bridges which have age-old structural shape make rapidly progress. Especially, the applications of concrete-filled steel tubular arch bridges have been made more and more. Span of such bridges develop from several dekameters to 460m in Wuxia Chang-Jiang River bridges.In erection of concrete-filled steel tubular arch bridges, people adopt different methods of construction to join the two sections of arch bridge such as cable suspend method and sewing method, then fill the concrete into steel tubes. A great deal of initial stress exists in steel tubes. At present, the study of the influence of initial stress is less on stability and bearing capacity for concrete filled steel tubular arch bridges. The article elaborates basic mechanical behaviors and calculation theories of bearing capacity on non-existing initial stress and existing initial stress concrete-filled steel tubular members. In terms of constitutive relation of existing initial stress concreted-filled steel tubular, author puts forward practical method of calculation on the influence of initial stress in concrete-filled steel tubular arch bridges. And establishs syntactic model of Zhejiang DongYang ZhongShan bridge with Marc finite element method. Under existing initial stress and no-existing initial stress conditions, author carries out numerical analysis of stability and bearing capacity of Zhejiang DongYang Zhong-Shan bridge. The results show initial stress reduces stability and bearing capacity of concrete-filled steel tubular arch bridge; the influence of initial is not equal to different load conditions, in some conditions, the influence of initial stress is higher and shouldn't be ignored; The mechanical behaviors of concrete-filled steel tubular arch bridges differ from concrete-filled steel tubular pillars in building-house construction, thus, the computational theories of concrete-filled steel tubular pillars can't be applied mechanically. These conclusions offer reference for thorough study of the initial stress in large span concrete-filled steel tubular arch bridges in future.