Seismic Response Analysis Of Long-span Combined Beam Cable-stayed Bridges Under Complex Site

Earthquake is a geological disaster with great destructive force.It often brings huge loss of life and property,for its difficult to predict and propagate rapidly.The cable-stayed bridge,as a kind of long-span bridge,is the throat of the traffic system.When the cable-stayed bridge is damaged,the direct and indirect losses are incalculable.In recent years,with the wide application of the cable-stayed bridge,it is very necessary to study the seismic analysis of the cable-stayed bridge under various conditions.The cable-stayed bridge has the characteristics of large span and complicated force,which means that the geological difference between the supporting points will affect the seismic response of the cable-stayed bridge greatly.Therefore,it is inappropriate to use the conventional seismic analysis method to analyze the uniform excitation of the cable-stayed bridge in the complex site.In order to simulate the seismic response of a cable-stayed bridge with complex sites,it is necessary to consider the impact of different geological conditions on the seismic waves,and considering the changes of seismic waves with time and geological changes,so that the bridge should be analyzed by the non-consistent excitation analysis of the actual geological conditions.To analyze the response of long-span composite girder cable-stayed bridge under the non-uniform excitation,this paper studied based on the construction of the Yumenkou the Yellow River bridge,and the main contents are as follows:1.Make a introduction of the reasons for the occurrence of earthquakes and the variation of seismic waves in the propagation process with time and geology,and elaborate the causes and effects of the three spatial effects,such as coherence effect,traveling wave effect and site effect.The results of other aseismic research workers are summarized,and the calculation models of the three spatial effects are introduced,and the appropriate models are applied to the ground motion response analysis in this paper.2.Make a briefly introduction of the Yumenkou the Yellow River bridge engineering background.The overall span layout and the detailed structure of the bridge are described.By analyzing the geological structure at the bridge site,the aseismic fortification grade of the bridge is determined.According to the actual situation of bridge,and use the finite element software SAP 2000 to carry out finite element analysis for bridge,select enough modes to superimpose,calculate the cycle,frequency and mode diagram of each mode of bridge,and analyze the dynamic characteristics of bridge in turn.3.Analysis the responds of Yumenkou the Yellow River bridge under consistent excitation,and compare the response spectrum analysis and time history analysis results.The design response spectra of E1 and E2 were calculated according to the standard,and the response spectrum was analyzed,and the analysis results of the key sections were obtained.According to the seismic wave selecting principle selected three suitable seismic wave and adjusted according to actual needs,and then input the adjusted seismic wave to SAP 2000 and make time history analysis of uniform excitation and obtain the result of the key sections.The results of the response spectrum analysis and the time history analysis were compared and analyzed.4.Considering the different influence of space effect on bridge,adopt different combination of the spatial effect of Yumenkou the Yellow River bridge excitation analysis.Considering the seismic response of coherence effect,combination of coherence effect and traveling wave effect,combination of coherent effect and site effect and three kinds of spatial interaction modes on the bridge,and design 14 conditions to analyze the different responds on the key sections on different effect condition.Comparison of the response of the key sections in different conditions,analysis the different seismic responds under different conditions.The contribution of different spatial effects to the response of bridges under the earthquake action is summarized,which provides the basis for the earthquake prevention and disaster prevention of the girder cable-stayed bridge.5.Summarizes the research work and the conclusions of this paper,and points out the problems that need to be solved in the further research.