| At present our country is entering on an active period during which construct of infrastructure in the west, the most crucial traffic construction in infrastructure construction is booming, as a hub of communications, the long-span Bridges have huge investment and it have a significant influence on the national economy. China is a country with frequent earthquake calamities, especially in the western. The long-span bridges were damaged in the earthquake, which subsequently brings about considerable economic losses and affect the post-disaster rescue efforts in disaster areas, therefore, it is very important to analyze the earthquake response and research the seismic-resistance measures for long-span cable-stayed bridges. This thesis aims at long-span cable-stayed bridge with twin towers, the main research work is summarized as follows:Taking Jiujiang Yangtze River Highway Bridge in the Jiangxi province as an example, this paper aims at studying the structural model of dynamic calculation, which is established by using ANSYS, the differences between the results of model fundamental frequency are not so significant that consideration of soil-pile interaction or not by means of calculation and Analysis the dynamic characteristics. Using the response spectrum of GB50011-2001 for spectrum analysis and selecting, Northridge wave, Kobe wave to earthquake elastic time history analysis under uniform seismic excitations, then choose the results calculated by EI-Centro wave are compared with the results determined by response spectrum, some conclusions about the vertical excitation increase the longitudinal seismic response of bridges, the multi-dimensional excitation control Transverse excitation and the three-dimensional excitation is the most disadvantage excitation way of the long-span cable-stayed bridge with twin towers are obtained. The tower of cable-stayed bridge with vertical and horizontal is analyzed of pushover by means of MIDAS mode method, the location of the first plastic hinge is found.Secondly: research on the seismic response effects of traveling wave effect on the long-span cable-stayed bridge with twin towers, and the effect of different wave velocity to the bridge is studied. The result indicates that the effect of traveling wave effect is obvious to the displacement of longitudinal and vertical, the effect on transverse displacement is negligible. On the other hand, the effect of traveling wave effect on longitudinal moment and longitudinal shear of south tower are obvious, but for other inner force is negligible. Therefore, the traveling wave effect must be considered when the earthquake response analysis of long-span cable-stayed bridge with twin towers.Finally, based on the earthquake response analysis, the seismic responses is reduced by setting the vertical and horizontal viscous dampers, the value of viscous damper parameter is proposed, the damping coefficient of longitudinal viscous damper is found while the position to control the displacement and inner forces achieve the best damping effect and the transverse damping coefficient is found which can improve transverse seismic response and it has the lest influence on reduce longitudinal seismic responses of bridges. |
