Seismic Response Spectrum Analysis Of A Single-Pylon Cable-Stayed Bridge With Dynamic Soil-Base Interaction

As important public facilities and the key components of transportation, cable-stayed Bridges play an important roles in the transportation network and safety is very crucial to people and civil engineers. Once bridges are destroyed or damaged by the earthquake, they will cause traffic disruptions and affect rescue, even bring greater economic losses. Due to the diversity and complexity of the bridge's seismic issues, here are any number of issues need further researches. Considering soil-base interaction (SBI), this paper analyzed the seismic response for a Single-Tower Cable-Stayed Bridge as the engineering background by using WenChuan earthquake acceleration response spectrum input. The main study works are as follows:(1) The usual models of dynamic soil-base interaction are reviewed and analyzed. In considering foundation damping effect combined with "m" approach, the soil-base interaction models used in paper and parameter formulas are given;(2) With reference to Guidelines for seismic Design of Highway Bridges (JTG/T B02-01-2008) results and previous research results, the fixed base model (FB model), the distribution spring and damper model (DSD model) and the lump spring and damper model (LSD model) for the pre-stressed concrete single-tower cable-stayed bridge are established(FEM). The static study of bridge model is calculated;(3) On the finite element model for vibration analysis, we have obtained the modal vibration characteristics of the structure and required modal order of the pre-stressed concrete cable-stayed bridge with single-tower. The result shows that the fundamental frequency decrease after taking the dynamic soil-base interaction into consideration, and the contribution of high-frequency modes structural deformation is smaller;(4) By using WenChuan earthquake acceleration response spectrum, the structure dynamic characteristics and deformation properties of cable-stayed bridge's three forms FEMs are analyzed. Comparative analysis of soil-base interaction effects on the seismic response of cable-stayed bridge. It turned out that if without considering soil-base interaction, seismic design of cable-stayed bridge will be unsafe;(5) The seismic history analysis result of three cable-stayed bridge finite element model with WenChuan earthquake excitation are computed. To compare with the response spectrum analysis results, first can be seen that both displacement and stress curve changes are consistent in the same order of magnitude. The relative difference is within 10% of the value, so in only the geometric nonlinearity conditions for single tower cable seismic analysis, the calculation accuracy of response spectrum analysis can be accepted. Secondly, considering SBI the model is better to use DSD.