Study On Dynamic Characteristics And Seismic Response Of Continuous Composite Bridge With Corrugated Steel Webs

In recent years,composite continuous bridge with corrugated steel webs has a rapid development in China,the largest main span exceeding 160 m.The static characteristics of this type of bridge have been increasingly improved in the field.With the popularization and application of this kind of bridge in mountains and high-intensity earthquake areas,the dynamic characteristics and seismic performance began to attract attention.Taking Qugang Expressway South-to-North Water Diversion Bridge as the engineering background,the seismic simulation shaking table test and the finite element analysis method are adopted in this thesis to study the dynamic characteristics and seismic response of the continuous composite girder bridge with corrugated steel webs.The main contents and conclusions of this thesis are listed as follows:(1)The continuous test beam with corrugated steel webs and the equivalent concrete continuous test beam were designed,and the seismic simulation shaking table test was carried out to measure the vibrational frequency and seismic response of the two test beams.The results show that the vibration frequency of the continuous beam with corrugated steel webs is lower than that of the concrete continuous beam,and the seismic response of the continuous girder with corrugated steel webs is lower,meaning better seismic performance.(2)The finite element model was established based on the test beam,and the accuracy of the finite element model was verified.Based on this finite element model,the parameter analysis was carried out.The results show that the transverse diaphragm can effectively improve the dynamic characteristics of the continuous girder with corrugated steel webs;increasing the thickness of the steel web can improve the stiffness of the box girder;with the increase of the inclination angle of the steel webs,the vertical bending stiffness and torsional stiffness of the box girder develop correspondingly,and the lateral bending stiffness first rises and then decreases;the length of horizontal plate of the steel webs does not affect the dynamic characteristics of the box girder;when the corrugated angle of the steel webs increases,the vertical bending stiffness of the box girder decreases,and the lateral bending stiffness and torsional stiffness tends to increase first and then decrease.(3)The seismic response of the continuous combined bridge with corrugated steel webs with the ordinary bearing and the friction pendulum bearing was calculated.The results show that the friction pendulum bearing can better improve the stress of the main beam and the piers,and also it can effectively reduce the displacement of the pier top and reduce the seismic response of the structure.So the friction pendulum bearing has good seismic isolation effect.(4)The effects of the curvature radius and dynamic friction coefficient of the sliding surface on the seismic isolation of the friction pendulum bearing were studied.The results show that with the increase of the curvature radius of sliding surface of the friction pendulum bearing,the longitudinal shear force of the piers bottom is reduced,and the longitudinal displacement of the beam increases first and then decreases.With the increase of the dynamic friction coefficient of the friction pendulum bearing,the shear force of the piers and the longitudinal displacement of the main beam both decreases.