Study On Influence Of Abutment On Seismic Performance Of Skew Continuous Beam Bridge

In the present,for the seismic design of skew bridges,it is assumed that the width between beam and abutment is large enough.There is no collision reaction between girder and abutment.Neglecting the influence of abutment on seismic response of skew bridges.However,some studies have shown that the interaction between abutment and orthogonal bridges can significantly change the seismic response of bridges.The influence of abutment should not be ignored in seismic design.As we all KNow,the dynamic characteristics of skew bridges are more complicated than orthogonal bridges.Therefore,the influence of abutment on the seismic response of skew bridge will be greater.It is necessary to conduct in-depth research to provide guidance for the seismic design of these structures.In this paper,the seismic damage characteristics of skew bridges and the current research situations are summarized.Based on a skew bridge project,the analysis model of this skew bridge is established by Sap2000 software.Firstly,the influence of skew angle on dynamic characteristics and ductility ability of piers is studied.After that,the influence of abutment on the response of skew bridge is studied under the two-way horizontal(longitudinal + transverse)seismic input.Finally,the influence of lateral block on the seismic performance of skew bridges is analyzed.Optimization suggestions on the selection of lateral block parameters(stiffness and width)are put forward.Through the research and analysis of this paper,the main conclusions are as follows:(1)Through the analysis of the dynamic characteristics of skew bridge,it shows that skew angle has a great influence on its vibration characteristics.For bridges with skew angle greater than 40 °,the coupling vibration characteristics of the longitudinal and transverse directions and rotation of bridges are obvious.(2)The change of skew angle will affect the ductility of piers.With the increase of skew angle,the ductility of piers in longitudinal direction will gradually increase,while that in transverse direction will gradually decrease.(3)Under the two-way horizontal(longitudinal bridge + transverse bridge)seismic input,the abutment can reduce the longitudinal response and the longitudinal force of the skew bridge,but it will aggravate the lateral response and the lateral force of the bridge,and reduce the lateral safety of the bridge.The greater angle of bridge,the more obvious influence of the abutment.(4)Under the action of earthquake,the greater angle of bridge,the stronger i MPact force at the obtuse angle of beam.The greater rotation moment of abutment to beam.The torsional moment of abutment to main girder is one of the important reasons for horizontal rotation of beam.(5)Setting lateral blocks on both sides of skew bridge can limit the lateral displacement and horizontal angle of beam.However,it will increase the lateral response and stress of piers and reduce the lateral safety of piers.(6)Through the analysis of parameters(stiffness and width)of lateral block,it is found that for skew bridges with different angles,the lateral block should be set with different parameters to improve the seismic performance.