Design Method And Construction Control For Long-Span CFST Arch Bridges

In our country, concrete-filled steel tubular (CFST) arch bridges have become a new technology of the bridge construction in recent years. It has the merits of light deadweight, great strength and strong distortion-resistant capacity. It can preferably satisfy requirements such as the materials for construction are saving, erection weight is light, the construction is simple, and bearing capacity is great. It is a kind of more ideal structure form for long-span arch bridges.The researches and applications about CFST structure have been taken about one hundred years in the world. But in China the researches have been taken since 1950s. Since 1990s, as a new-style combined material with favorable mechanical behaviour fit for arch bridges, CFST has been getting broad application and rapid development. The research in this thesis is concentrated on the basic calculation and construction control theory of CFST long-span arch bridges. The main contents are summarized as follow:1. Three different theory system together with relative design codes, which have been wide applied in China at present, are introduced and compared. Structure configuration and computational methods about CFST structure, which are prescribed in the domestic and foreign design standards (regulations), are analyzed.2. Starting with the introduction of erection methods of arch bridges, different erection methods and their applicability are analyzed briefly. Accordingly, construction issues are pointed out when using CFST for long-span arch bridges. The erection methods of CFST arch bridges are substantially the rigid skeleton method and the self-spanning method. Two main methods of the cable crane-assembly method and the rotation method forming span of steel tube skeleton are emphasized.3. This thesis introduces briefly the construction control principles and contents for long-span bridges. The main factors that affect the error of construction control in the constructing process of CFST arch bridge are analyzed, and the means applied to reduce these errors are proposed.4. On the project background of Rongzhou Bridge, a half through CFST arch bridge in Yibin crossing Jinshajiang, the optimizing theory is applied to the calculation of the stayed-buckle-cable forces in the process of craning construction of the steel-tube arch segment and construction error adjusting. The calculated optimum cable forces with high precision can guarantee the inner forces and the structuredeformation in safe state, and ensure the line shape of the arch ring in accordance with design requirements as well.