Seismic Study On Performance Of Double Column Pier

Double column pier are widely used in China's medium and small span highway bridges and urban viaducts.Due to their have small displacement of the top of the piers,high number of structural indeterminations and strong lateral forces and so on in the earthquake.However,when the height of the pier is high,the rigidity of the pier will cause a large horizontal displacement at the top of the pierin in the level earthquake,which will easily cause the beam to fall off and be damaged.In addition,due to the relatively small cross-section size of the pier,the bending and shear resistance of the pier bottom is also weak,and the pier is more prone to bending and shear failure.Therefore,the paper selects the double column pier bridge as the research object.Based on the analysis method of the seismic design of the bridge,based on the ductile seismic design,using Midas civil finite element analysis software to perform static elastoplastic analysis and dynamic time history analysis.Explored the influence of the piers' own design parameters,the setting of transverse beams and the action of water on the seismic performance of double column pier and bridges.The following main conclusions are reached:1.The analysis of the double column bridge pier in different piers' own design parameters and seismic response analysis has led to the following conclusions:(1)The capabilities and the ductility of the pier are in a better when the shear span ratio between 6 and 8.(2)As the axial compression ratio increase,the displacement capacity decrease,the bending capacity and bending moment requirements increase.It is recommended that the axial compression ratio be designed to be around 0.15.(3)As the longitudinal tendon ratio increase,the curvature ductility will gradually decrease,and the displacement capacity demand ratio of the structure first increase and then decrease,and it reach maximum when the longitudinal tendon ratio is 1.0%,the bending capacity is increased.Considering the requirements of seismic performance,the longitudinal reinforcement ratio is preferably about 1.0%.(4)With the increase of the volume coupling ratio,the ultimate curvature of the section and the ductility are significantly increase.When the volume coupling ratio is about 1.5%,the section curvature ductility tends to a fixed value and the bending capacity and bending moment requirements are basically unchanged.2.The setting of cross tie beams between pier and pier can improve the bending capacity and displacement capacity in the transverse direction of the bridge.But it is not good for the shear resistance of the bridge and has no effect on the ability of the bridge in the direction of thebridge.However,with the increase of the number of transverse tie beams,the utility of the tie beams gradually decreases.3.Influence of comprehensive factors such as water depth and water content,the change trend of bridge pier displacement shows a trend of decreasing first and then increasing,which is different from the simple consideration of water depth.Among them,dynamic water pressure has the most influence on shear force.protruding.Therefore,in the design of bridge pier in water,the influence of water content and dynamic water pressure on the seismic performance of the bridge must be considered at the same time.