The Seismic Response Analysis Of Long-span Cable-stayed Bridge Under Different Patterns Of Earthquake Excitations

As a destructive and unpredictable natural disaster, the earthquake occurred that would cause huge loss of lives and property, in particular the damage of the long-span cable-stayed bridges. Therefore, it is of great theoretical and practical significance to conduct comprehensive and systematic investigation on the earthquake-resistance of bridge.On the basis of the vibration theory of the long-span cable-stayed bridges and the achievements of theoretical investigation of aseismic analysis at home and abroad, the development history of aseismic analysis of bridge is introduced and the advantages and disadvantages of these methods are analyzed. On the above research and basic tenets, a study of the seismic response analysis of the long-span cable-stayed bridge with double tower and double cable plane is conducted using response spectrum and dynamic time-response analysis method as Xiaoshawan Yellow River Super Bridge of Inner Mongolia for engineering background, including the following aspects.Firstly, the space finite element dynamic calculation model is developed with the advanced analysis program ANSYS and the dynamic properties are obtained through modal analysis. The results accord with the characteristics of half-floating cable-stayed bridges.Secondly, based on the structure of the vibration characteristics, the response spectrum analysis and the same incentive linear time-history analysis are studied with the longitudinal, transverse, vertical and three-dimensional seismic input. By comparison, there are significant differences between the two results. For the sake of safety, the seismic analysis of the bridge should be conducted by means of combining the two theories to get satisfied results.Again, considering the geometry nonlinear factors of the long-span cable-stayed bridge of seismic response analysis, the nonlinear time-history analysis is conducted under the consistent excitation. From the different response results of linear time-history analysis and geometric nonlinear time-history analysis,the response results of the seismic analysis are strongly influenced by the geometry nonlinearity of the bridge.Therefore,the geometry nonlinearity must be taken into account in seismic analysis of long-span cable-stayed bridges.Fourthly, based on the dynamic formula of seismic responses of structures under the non-consistent excitations, the structural dynamic responses to traveling-wave effect are studied.The acceleration time-history is translated into force time-history with big mass principle,and force time-history is exerted in support place.By comparing the structural responses to the consistent and non-consistent excitations, the traveling-wave effect to the responses of the long-span cable-stayed bridge is closely related to the time-lag of seismic wave between the two towers.Finally,the vibration analysis of Xiaoshawan Bridge takes into account the structural elastic modulus,pile-soil-structure interaction,different damping modes and the number of modes.The analysis shows that the structural responses may endanger the safety by considering the changes of structure parameters and the influence rules and extent are not exactly in the same way,which provide an important reference for seismic design and analysis of long-span cable-stayed bridges.These laws can be used as the basis of seismic design of Xiaoshawan Bridge and is useful for directing seismic response analysis of such kind bridge.