Seismic Performance Of Super Long Span Concrete Arch Bridge With CFST Stiffened Skeleton

This thesis firstly introduces the development of arch bridge stiffened with concrete-filled steel tube and some elementary knowledge related to bridge aseismic design. Using the response spectrum method and the dynamic time-history analysis method and combining with Beipanjiang Bridge (draft design), the aseismic behavior of long span arch bridge is analyzed by numerical simulation with finite element software. The contents and conclusions of the study are as follows.With the results of modal analysis of the main arch ring and the full bridge, the major periods and vibration modes can be gotten, and then the dynamic performances can be analyzed and compared. It shows that superstructure has great influence on the dynamic performance of main arch ring by reducing its natural vibration period and the influence is greater in the transverse direction than in the longitudinal direction.The seismic responses in the transverse and the longitudinal direction of the main arch ring and the full bridge are calculated by the response spectrum method. By comparison of the seismic responses, such as displacements, internal forces, stresses and support reactions, it shows that superstructure will swing under seismic loads which can reduce the vibration of full bridge and therefore inhibit the seismic response of main arch ring.With the seismic excitations, the lateral displacement of superstructure will be great. Besides, the girder falling and block damage accident may happen in earthquakes. Therefore it is suggested that some measures should be taken to prevent similar events in long span bridge design process. For example, one can set some lateral connecting devices in the bridge junctions and pier-beam joint.The vertical earthquake has a great influence on the vertical displacement of bridge-superstructure. Therefore, in the process of bridge design, one should pay enough attention to this situationBasically, Beipanjiang Bridge (draft design) in the earthquake under the function of response spectrum can meet the requirements. Just in the vertical earthquake, the bottom of the main arch ring may appear larger stress. Through the dynamic time-history analysis method, the analysis of the earthquake response of the main arch ring and the full bridge model is given in the action of two kinds of seismic waves. The analysis shows that the bridge-superstructure will not always aggravate or inhibit seismic response of main arch ring, while it is related to the spectrum characteristics of the seismic wave, the dynamic performance of the main arch ring and the mode shape of the bridge-superstructure excited by seismic wave and other factors.