Dynamic Characteristics And Seismic Response Analysis Of Low-pylon Cable-stayed Bridge

Low-pylon cable-stayed bridge is a new type of composite system bridge that has risen rapidly in recent years.It is a bridge type between the rigid continuous beam bridge and the flexible cable-stayed bridge^[1].Its structure features are the bridge tower height is small,the main beam stiffness is large,the cable spacing is small,more concentrated.Bridge tower height is small,when the bridge is set up near the airport where the height of the bridge is strictly limited,the use of low tower cable-stayed bridge is more appropriate.Also in the city construction,the short tower cable-stayed bridge has a wide range of application space.Due to the frequent earthquake disasters in China in recent years,the importance of bridge engineering as the lifeblood of transportation is self-evident,so it is necessary to study the seismic design of short-pyloned cable-stayed Bridges,and the dynamic characteristics and seismic response analysis are the basis of seismic design research.At present,with the increase in the number of short-pylon cable-stayed Bridges,the theoretical test and research on short-pylon cable-stayed Bridges are deepening,and the construction techniques are becoming more and more mature.However,the research on the dynamic characteristics and seismic response of short-pylon cable-stayed Bridges is not perfect,especially for the high-pylon cable-stayed Bridges.This article in view of short tower cable-stayed bridge dynamic characteristics and seismic response analysis of the problems lack of experimental evidence theory model research,will be a new domestic tower type of short tower cable-stayed bridge as the engineering background,using finite element software Midas/Civil2018 to establish finite element model of the bridge,the dynamic characteristics analysis,and by using the measured self-vibration characteristic test to verify the accuracy of the theoretical model.Then the seismic response result is calculated by the model modified by the experimental data,and the result is more accurate.Some design parameters,such as tower height and cable stiffness,are selected as dynamic parameters.The dynamic characteristics of cable-stayed bridge with high tower type and short tower type are studied by these parameters and the influence of these parameters on the dynamic characteristics of cable-stayed bridge with high tower type and short tower type is quantitatively analyzed.Based on the study of the characteristics of natural vibration,the seismic response analysis in the longitudinal,transverse and vertical directions of cable-stayed Bridges with high pylons and short pylons is calculated by response spectrum method and time history analysis method.The response spectrum curve is drawn according to the design of the bridge site and geological data to determine the site category,seismic fortification intensity and site characteristic period of the cable-stayed bridge.The seismic wave is also selected according to the bridge site category and site characteristic period 7 similar representative,after the adjustment of its input structure,the bridge in the time history analysis and calculation of the general law,and comparative analysis of the results and laws of the two methods are different.The interaction of pile-soil structure and the influence of bridge tower height on seismic response are analyzed.