地震作用下斜交空心板桥地震响应分析及其评价

Analysis and evaluation for seismic response of skew hollow slab bridge under seismic action

针对斜交空心板桥,运用有限元方法分析地震作用下桥梁的地震响应特性,并对其抗震性能进行评价,对不满足要求的地震响应提出应对措施。结果表明:在地震作用下,斜交桥的地震响应特性较直桥更为复杂,靠近承台的墩柱和桩基的地震响应较中间墩柱大,可达到中间墩柱地震响应的1.1~1.6倍;盖梁内部产生轴向压力和拉力;主梁扭转效应显著,支座受力分布不均匀,部分支座发生脱空和超压,处于斜桥锐角最边缘处的支座最易脱空,从锐角至钝角方向压力逐渐增大。在地震作用下,墩柱受剪、支座受剪、受压及变形均可能不满足承载能力的要求,并且支座会发生滑移。在设计时,需考虑盖梁轴力其对受弯及受剪承载力的影响;需选取适宜的支座型号,使其满足承载能力和变形的要求;对支座脱空问题,可通过调整支座竖向刚度予以控制,或设置抗拉支座;对支座滑移问题,可通过采取防落梁措施予以解决,横桥向可设置抗震挡块,纵桥向可设置纵向挡块、限位锚栓或拉索式连梁装置。

In view of skew hollow slab bridge,the seismic response of the bridge under the action of earthquake was analyzed by using finite element method,and its seismic performance was evaluated,furthermore the countermeasures for the seismic response that did not meet the requirements were put forward.Results showed that under the seismic action,the seismic response of skew bridge was more complex than that of straight bridge.The seismic response of pier column and pile foundation close to bearing platform were larger than those of intermediate pier columns,which could reach 1.1-1.6 times of the seismic response of intermediate pier column;axial compression and tension were generated in the capping beams;the torsional effect of main beam was significant,and the distribution of bearing force was uneven,meanwhile some abutments were hollowed and over pressured,which was at the extreme edge of skew bridge acute angle.The abutment at the edge was easy to be detached,and the pressure increased gradually from acute angle to obtuse angle.Under the action of earthquake,the shear of pier column,shear of abutment,compression and deformation might not meet the requirements of bearing capacity,and the abutment would slip.In the design procedure,it was necessary to consider the influence of the cover beam’s axial force on the bending and shear bearing capacity.To select the appropriate abutment type to meet the requirements of bearing capacity and deformation.To solve the problem of abutment void,it could be controlled by adjusting the vertical stiffness of the abutment,or setting the tensile abutment.To solve the abutment sliding problem,the anti-falling beam measures could be taken,and the anti-seismic blocking could be set in the transverse direction of the bridge,longitudinal block,limit anchor bolt or cable coupling device could be set in longitudinal bridge direction.