曲率半径和激励角度对刚构桥地震响应的影响

Study on the Effect of the Curvature Radius and Seismic Excitation Angle on the Seismic Responses of High Pier and Long-span Continuous Rigid Frame Bridge

目的研究曲率半径和地震动激励角度对高墩大跨连续刚构桥地震响应的影响,确定该类桥型的最不利地震激励方向.方法以某跨度为(70+3×127+70)m的公路连续刚构桥为背景进行分析,采用有限元法建立全桥模型,并考虑桩-土相互作用,探讨曲率半径对结构动力特性的影响;采用反应谱法研究地震作用下桥梁结构的内力和位移响应.结果分析结果表明:曲率半径对该类桥的自振特性有较大影响,随着曲率半径的减少,结构的自振频率和整体刚度逐渐降低;在纵桥向激励时,随着曲率半径的增大,桥墩纵桥向的内力及位移均有增大趋势,在横桥向激励时,随着曲率半径的增大,桥墩横桥向的内力及位移变化规律不明显.结论该类桥梁的最不利地震动激励方向并不是纵桥向和横桥向,其最不利地震动激励角度大致为80°和165°.

In order to study the effect of the curvature radius and seismic excitation angle on seismic response of the high pier and long-span rigid frame bridge,and determine the most unfavorable earthquake excitation direction of this kind of bridge,a highway rigid frame bridge with span arrangement（70＋3×127＋70） m was taken as an example and analyzed.The whole bridgeis modeled by the finite element software considering the pile-soil interaction,in which the effect of cur-vature radius on the structural dynamic properties was discussed.In addition,the internal forces and displacements under the seismic action were analyzed based on the response spectrum method.The analysis results show that radius of curvature has a great effect on the natural vibration characteristic of this bridge.At the same time,the structure natural frequency and the overall stiffness decrease gradually with the curvature radius decreasing.With the curvature radius increasing,the internal force and the displacement of the pier in longitudinal direction increase gradually under the excitation of the longitudinal direction,while they change irregularly in transverse direction under the excitation of the transverse direction.The critical excitation direction of the ground motion is neither longitudinal nor transverse direction,while the critical seismic excitation angles are about 80° and 165°.