| Curved girder bridges have been widely used in expressway ramps and urban viaducts.However,due to the complex mechanical characteristics of curved girder bridges,they have been severely damaged in recent major earthquakes,and they often appear to climb.The investigation found that different upper and lower connecting members,limit members and different structural parameters of curved beam bridges will cause large differences in the seismic performance of the structure.In view of this,this paper uses the response spectrum method,the time history analysis method,and combined with the finite element analysis software to use a small radius curved prestressed concrete(Pretensioned Concrete PC)continuous curved box girder on a highway ramp in a high-intensity area.The bridge is a supporting project,and the seismic performance of a small radius curved beam bridge is studied,and the influence of different ground motion acceleration,curvature radius,bridge pier height,block parameters,and support restraint system on the ground motion response of the curved beam bridge is analyzed.The main research contents and results are as follows:(1)The high-speed ramp bridges of the same type of prestressed concrete curved girder bridges were investigated and analyzed,a total of 30;and using finite element software,the main girder and supporting beams of the curved girder bridge under constant load,prestress and temperature were analyzed.The deformation of the seat is found to be more consistent with the research situation.The results show that in the daily operation of curved girder bridges,shear deformations of supports that are unreliable and self-recoverable,changes in expansion joint spacing,and damage to seismic blocks often occur,which will affect the seismic performance of the entire structure in severe cases.(2)Based on the multiple Ritz method,the influence of different curved girder bridge structural parameters on the structural dynamic characteristics is analyzed.The results show that the vibration modes of the curved beam bridge are coupled with each other,and it is impossible to vibrate in a single direction.The influence of the change of the radius of curvature on the dynamic characteristics of the curved girder bridge is mainly at the high-order frequency,while the change of the pier height has a relatively obvious influence on the low and high-order.The higher the pier height,the lower the natural frequency of the structure.(3)Based on the response spectrum analysis method,analysis and summary of the influence of different radius of curvature,different pier height changes and ground motion input angles on the ground motion response of curved girder bridges are analyzed and summarized.The analysis results show that the most unfavorable ground motion input angles for different key parts of the curved beam bridge structure under different curvature radii are different,and the seismic requirements are inconsistent.Comprehensive consideration is needed to achieve a good overall control effect for the structure;from the response results,The curve beam bridge is more sensitive to the seismic excitation in the transverse direction;as the radius of curvature decreases,the radial displacement of the superstructure and the radial shear force at the bottom of the pier increase;as the height of the pier increases,the shear force at the bottom of the pier Weakened,but the displacement of the pier top and the displacement of the main beam increase significantly,which will increase the collision effect of the main beam in the vertical and horizontal directions and the risk of beam drop.(4)Based on the time-history analysis method,combined with ANSYA and MADIS software to analyze the different bearing restraint systems,"climbing" caused by structural parameter changes,the impact of stopper strength and gap changes on the seismic response of the structure,and the impact of lead rubber The seismic isolation performance of the seismic isolation support has been compared and analyzed.The influence law of each setting parameter change on the structure,the damage mode of each structural component under different restraint systems,and the structure ground motion response change law caused by creeping are obtained. |
