Seismic Performance Analysis Of Concrete Filled Steel Tube Curved Chord Truss Bridge

The concrete filled steel tube curved chord truss bridge has the advantages of flexible layout,beautiful appearance,strong spanning ability,large bearing capacity and prominent structural mechanical properties,so it is applied in bridge projects.As the service time of the bridge is extended,the performance of the bridge is gradually degraded,maintenance and reinforcement are required to improve the service capability of the bridge.Therefore,this paper relies on a certain highway concrete filled steel curved chord truss bridge and studies the changes of the vibration characteristics and seismic performance,and will provide references for seismic design and determination of reinforcement plan of the curved chord truss bridge.The main work of this paper is as follows:1.According to the characteristics of concrete filled steel tube curved chord truss bridge,four finite element models pre and post reinforcement of concrete filled steel tube curved chord truss bridge with spans(62m and 122m)are established by using finite element software ANSYS.2.Analyzing the vibration characteristics of concrete filled steel tube curved chord truss bridges pre and post reinforcement,the results show that after strengthening the bridge,the base frequency of the 62 m bridge increased from1.741 Hz to 2.103 Hz,and the base frequency of the 122 m bridge increased from0.719 Hz to 0.773 Hz,all of which exhibit the lateral vibration of the main truss,indicating that the lateral stiffness of the main truss of the bridges is relatively weaker;the vertical stiffness of reinforcement bridges has been improved,among the vertical stiffness of bridge decks and the torsional stiffness of the bridges have been significantly improved,and the out-of-plane stiffness of the main truss has not increased significantly.3.The seismic responses of concrete filled steel tube curved chord truss bridges pre and post reinforcement are calculated by using response spectrum method.The results show that the fixed-end and 3/4L position of the upper chord are the seismic vulnerability of the original bridges,and the displacement is most significant in thecross-bridge direction,indicating that the lateral stiffness of the main truss is relatively weaker.The axial force and displacement of the reinforced bridges are reduced to a different extent than the original bridges,indicating that the seismic performance of the reinforced bridges is improved,and the reinforcement scheme can improve the seismic performance of the bridges.4.The seismic responses of concrete filled steel tube curved chord truss bridges pre and post reinforcement are calculated by using time-history method.The results show that the maximum internal force of the bridges pre and post reinforcement occurs at both ends of the upper chord,the internal force and displacement of reinforced bridges are reduced compared with the original bridges;the lateral stiffness of the main truss of the bridges is relatively weaker;there is a certain gap in the calculation results under different seismic waves,but the basic rules are roughly the same.5.The calculation results of the response spectrum method and the dynamic time-history method are compared,the results show that the former is smaller than the latter,but the basic rules of the results obtained by the two methods are consistent,and both reflect the seismic performance of concrete filled steel tube curved chord truss bridges.