Analysis On Seismic Response Of Double X-arch Bridge And Isolation Effect Of Isolation Bearing

The double X-arch bridge is novel-looking and a new type of arch bridge without the traditional transverse bracing. The stress and the structure of double X-bridge is very complex and is quite different from conventional arch bridges. Over the past decade, high magnitude and large destructive earthquake disaster occurred more and more frequently, this is a great test for the bridge buildings regarded as the lifeline engineering. In this paper, choosing a double X-arch bridge crossing the Xinhe River on the Dongting Road, Changde city, Hunan province as the example which is a concrete-filled steel tube arch bridge, and using the finite element method, main research work and conclusions relating to seismic responses behavior of this type of bridge and the isolation effects of isolation bearing have been studied as follows:1. The analysis of the self-vibration characteristics of a double X-arch bridge. The influence on the dynamic performance of this type of structure is investigated when the inclination angle of inclined arch changed, the rigidity of arch rib and the main beam changed, the number of cross-brace changed, and the use of different bearing system, etc.2. The analysis of seismic response of double X-arch bridge. analyze and summarize the seismic response characteristics of double X-arch bridge by the methods of response spectrum analysis and time-history analysis. Analyze the influence on the seismic response behavior of double X-arch bridge as a result of the change of main structure parameters, and put forward some useful design recommendations on the seismic design of this type of bridge.The results show that time history analysis and spectrum analysis method for the calculation of the structure seismic response basic is basically consistent, and time history analysis result is slightly less than the spectrum analysis results. 3. propose a new method that using three-dimension combination of the spring element to simulate isolation bearing, and verify the applicability of the proposed method by an instance of a single degree of freedom system. Analyze and compare the isolation effects when used different isolation bearing in the double X-arch bridge, and discuss the main factors affecting the isolation effect of isolation bearing, The results show that the isolation bearing has a certain effect on extending the bridge vibration cycle as a result of having damping and energy dissipation characteristics, the isolation effect is obvious. At last, make some preliminary recommendations on the seismic design of double X-arch bridge about the design of isolation bearing.