Study On Seismic Displacement Control Of Continuous Skew Girder Bridges With Elastomeric Pad Bearings

Using a typical continuous skewed bridge in Wenchuan earthquake as a bridge example,OpenSEES software is used to establish a three-dimensional refined nonlinear finite element analysis model.Taking the Mianzhu Qingping ground motion in the Wenchuan earthquake as the excitation,the longitudinal and lateral displacement response of the girder,the shear deformation damage of the bearing,and the bending moment curvature response of the longitudinal and lateral directions of the pier are analyzed,and the typical continuous skewed bridge is evaluated.The seismic performance of the bridge.The research shows that the seismic displacement of the upper structure of the continuous skewed bridge has obvious coupling effect,and the longitudinal and lateral displacements are 0.21 m and 0.18 m respectively;the elastomeric pad bearing has severe shear failure;the lateral limit stop is seriously damaged.However,there is no obvious shape-fitting phenomenon in the lower pier column,and the girder has a large risk of falling beams.(2)Based on the above-mentioned typical continuous skewed bridge,a series of continuous skewed bridge are constructed with parameters such as pier height,skew angle and span number,and parameter analysis is carried out to design continuous skewed bridge with different structural parameters.The parametric comparison analysis of the bridge reveals the influence of different structural parameters on the seismic displacement response of the continuous skewed bridge under earthquake action,and lays a foundation for the seismic displacement control method of the continuous skewed bridge.The research shows that the increase of the friction coefficient of the bearing can reduce the shear deformation of the bearing and reduce the plane angle of the girder,but the response of the pier will increase continuously.The increase of the skew angle will make the girder horizontal.The displacement increases and the longitudinal displacement decreases.When the skew angle is 45°,the curvature of the pier and the plane angle of the girder have the largest response.The reason is that the longitudinal and lateral coupling effects are the largest under this condition;The increase(1 span ~ 4 span),the longitudinal and transverse shear deformation of the bearing firstly decreases and then increases.The longitudinal and lateral displacement of the girder increases first and then increases;The longitudinal and transverse shear deformation of the side span support increases,but the longitudinal and transverse shear deformation values of the mid-span support decrease,and the longitudinal shear deformation is more affected by the height of the pier than the transverse direction.(3)Based on the results of parameter analysis,select the representative bridges which are the most unfavorable in the parameter analysis as the research object,and carry out the research on seismic displacement control methods.By comparing various limit devices and their influence rules,The optimal displacement control method is proposed.The research shows that the reinforced concrete block and the X-shaped steel shear key can restrain the lateral displacement of the girder,but there is no limiting effect on the longitudinal displacement.On the basis of the lateral limit method,the shock transmission unit is used to simultaneously perform the longitudinal displacement.Limitation,when the stiffness of the shock transmission unit bearing is 100kN/m,the longitudinal and lateral displacement of the main beam can be effectively controlled.