Influence Of Auxiliary Pier On Static And Dynamic Response Of Double-tower Cable-stayed Bridge Under Near And Far Field Earthquakes

The static and dynamic response of cable-stayed bridge under near-field and far-field earthquake is still the key problem in the design of cable-stayed bridge.The height of Auxiliary Pier,layout,connection mode of tower and beam,relative stiffness of tower and beam,and structural system of cable-stayed bridge have great influence on the static and dynamic response of cable-stayed bridge under earthquake.In order to study the influence of Auxiliary Pier on the static and dynamic response of double tower cable-stayed bridge under near-field and far-field earthquake,firstly,the research status at home and abroad and the research content of this paper are introduced.Secondly,taking a double tower cable-stayed bridge in southwest mountainous area as the research background,the influence of Auxiliary Pier and different auxiliary pier height on the static stability and natural vibration characteristics of double tower cable-stayed bridge is explored Finally,the parameter sensitivity of double tower cable-stayed bridge under near-field earthquake and far-field earthquake is studied,The main conclusions are as follows:(1)The internal force and stability of the auxiliary pier are greater than the corresponding value without auxiliary pier,but the displacement response of the auxiliary pier is less than that of the non-Auxiliary Pier.With the increase of the height of the auxiliary pier,the internal force response of each key point decreases,and the displacement response of the key point increases accordingly.The fundamental frequencies of non-Auxiliary Pier and auxiliary pier are 0.196Hz and 0.268Hz respectively,which are in good agreement with the calculated values in the code.With the increase of the height of the auxiliary pier,the main frequencies decrease,especially for transverse bending,vertical bending and symmetrical torsion.Compared with the minimum pier height,the transverse bending,vertical bending and torsion frequencies of the maximum pier height are reduced by 53.5%,57.5% and 30.0% respectively.(2)The results show that the tower pier height of the original system is the most suitable tower pier height under earthquake action,and the top displacement and mid span deflection of the tower are the minimum,while the bending moment at the bottom of the tower is not large.The results show that the top displacement and mid span deflection of the three systems have little difference,but the bottom bending moment of system 2(semi floating system)is the smallest,so the semi floating system is the most suitable system among the three systems.(3)The stiffness of tower beam has little influence on the longitudinal displacement of tower top,but has great influence on the transverse displacement,which can be reduced by 57.9%;The mid span deflection decreases with the increase of tower beam stiffness,while the tower bottom bending moment increases with the increase of tower beam stiffness.The bending moment of main girder has little change under the action of different pier height and different tower beam relative stiffness,but it increases with the increase of pier height in a certain range,and decreases with the increase of tower beam relative stiffness.(4)The displacement response and internal force response under near-field earthquake are greater than those under far-field earthquake,and the longitudinal displacement of tower top and axial force of end stay cable under X+Z condition are greater than those under Y+Z condition,but the bending moment of tower bottom is relatively affected by transverse earthquake.(5)The setting of auxiliary pier can significantly reduce the side span bending moment(41.2%)and mid span deflection(21.5%),and reduce the bending moment(8.3%)and end Stay Cable axial force(4.4%)of mid span girder to a certain extent,making the structure more reasonable.(6)Under the semi floating system,the top displacement and bottom bending moment of the tower are the smallest,but the vertical displacement in the middle of the span is slightly larger,but it is not different from the other two systems.