| The research and the application of CFST arched bridge in china are in the world advanced level, As a result of the good compressive capacity of CFST, enables the concrete filled steel tube arch bridge's spanning ability to have the very big superiority. Thus in great span bridge's research and design, CFST arch bridge stand out of numerous bridge types. Compared with continuous gride bridge, the CFST arch bridge's dead weight is smaller in spanning the greater distance's situation. There have been developing the studies of 600m and 1000m CFST arch bridges'to try to design in Japan and Croatia. Although there have not relevant research in china, as economic developing and technology continues innovation, CFST arch bridge will have to be concerned by more and more researchers in Engineering and academia.As a transport hub,the earthquake resistance of bridge is much accounted of numerous researcher, Because its application and development in a short period, and it's Stress mechanism is complicated, the theory of CFST is not mature. In China—a Multi-earthquake country, the seismic response of long span bridge is the important problem of researchers concerned.Analyzed the dynamic performance of Qiandao Lake Nampu bridge original structure in the subspace iteration method, and has listed the first ten step mode of vibration and the frequency. Then, compared with the date from scene examination of other same types bridge, has studied this bridge's dynamic performance. Obtained that the rigidity out of place of Nanpu bridge is bigger than the rigidity in place; the base frequency is small, and the structure is supple. Applying time history method analyzed the earthquake resistance performance of this bridge, considering of the disadvantage angle of Seismic waves input, have done the research of seismic response on this bridge separately under seven situation—0°,15°,30°,45°,60°, 75°,90°. Compared the distortion and the stress situation of arch rib under each kind of situation, it's shows that the vertical earthquake function cannot be neglect for the great span arch bridge, and the disadvantage angle of Seismic waves input should be considered.The rib of Limbs truss CFST arch bridge is composed of four concrete filled steel tubes, which is connected together by the steel tubes without concrete filled. In order to study the concrete filled in the rib to the whole structure's behavior, selected the whole or part of the rib not filled with concrete. Has studied the distortion and the stress situation of each kind of model's arch rib under the variable load and the permanent load, Analysis the difference of dynamic performance between the various models and the original structure, and the reasons of the changes happened. In addition, studied the seismic response of the five models in time history method, the date shows, when selecting the up two tube or the inside two tube not filled with concrete, it would not only save the amount of concrete, but also reduce the construction difficulty. And the influence to the structure's behavior is under the scope of safety.Transverse brace is the most important element of protecting the lateral rigidity of CFST arch bridge. Its'quantity and the arrangement form are playing very important role in the structure behavior. To obtain the influence of transverse brace to the dynamic property of rib, re-arranged the transverse brace, studied the seismic response of the four models in time history method. Compared the distortion and the stress situation of arch rib, draws the conclusion that reduce the quantity of transverse brace may increase the vertical displacement of rib, but it would not increase the horizontal displacement and the stress of rib.
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