Nonlinear Analysis Of Seismic Response Of Long-span Concrete-Filled Steel-Tubular Arch Bridge

In recent years, with concrete-filled steel tubular (CFST) structure of the theory of continuous improvement, the application of CFST arch bridge has been developing rapidly. The seismic resistance question needs the deep research on the long span CFST arch bridge. At present, the long span CFST arch bridge's earthquake resistance question is not clearly defined in China's code. From the bridge seismic literature, the study of seismic response is still less on the long-span CFST arch bridge. In the dissertation some problems relating to seismic response behavior of CFST arch bridge are studied.The dissertation takes the bridge dam project (steel pipe concretes arched bridge) as the background in HANZHONG city. The finite element model established has suited in the seismic response analysis. It considers the selection of the main arch rib model on the seismic response analysis effect. In the model buildingâ… ,â…¡, compared displacement response time-history on the key cross-section of the models in the three-dimensional excitation, it shows the model selection influence to be big. Taking use of the method of the time-history analysis, it has discussed the vertical excitation, the multi-dimensional excitation influence. It obtains the vertical seismic to excite that changes the distribute rule of each control unit internal force, and the vertical seismic excitation can be not neglected. It also indicates that the three-dimensional excitation is the most disadvantage excitation way on the seismic response of the long span CFST arch bridge. The peak value of horizontal displacement,in-plane bending moment My is remarkable under the three-dimensional excitation. It indicates that the transverse response of the arch rib is basically controlled by transverse excitation and the coupling mode of vibration function is not obvious.Secondly, the seismic response behavior of the bridge model is studied on the traveling wave effect. And the effect of different wave velocity to the displacement and element force is studied.The result indicates that the effect of transverse seismic excitation to the displacement of the traveling-wave direction is obvious and the effect to the element force is also negative. If the wave velocity is slower, the effect to the displacement and element force are more obvious. So it is necessary to consider the seismic traveling wave effect of the long span CFST arch bridge.Finally, in the linear seismic response analysis's foundation, the dissertation has further studied the effect of geometry nonlinear, material nonlinear which responds to seismic response of the long span CFST arch bridge. It obtains that the geometry nonlinear is not to be obvious to the effect of the arch bridge, but the effect of the material nonlinear is obvious.