异型钢独塔斜拉桥抗震性能分析

青海省西宁市西平大街异型钢独塔斜拉桥的结构、交通荷载较为复杂。为了保证该桥的抗震安全，使项目能够顺利进行，从桥梁空间动力模型建模、摩擦摆支座模拟、地震动输入方向3个方面进行分析，完成了桥梁的建模计算。结果表明：沿纵桥向输入地震动时，边塔的轴力和剪力远大于主塔，而沿横桥向输入地震动时，主塔的轴力、剪力和弯矩均大于边塔；选用的摩擦摆减隔震支座设计减隔震起始力为竖向承载力的10%，在E2强震作用下，支座进入减隔震摆动工作状态，有效延长了结构自振周期，实现了该桥减隔震设计；伸缩缝的设置应预留足够梁体位移量，以避免地震时梁体与桥台发生碰撞；桥台与主梁之间设置黏滞阻尼器，可有效控制梁体和桥塔的纵向位移，并起到减震耗能的作用。

Analysis on Seismic Performance of Special-shaped Steel Single-pylon Cable-stayed Bridge

The structure and traffic load of the special-shaped steel single-pylon cable-stayed bridge in Xiping Avenue in Xining City of Qinghai Province are complicated. In order to ensure the seismic safety of the bridge and make the project able to implement smoothly, the analysis is carried out from three aspects of bridge spatial dynamic model modeling, friction pendulum bearing simulation and seismic motion input direction. The modeling calculation of bridge is completed. The result shows that when the seismic motion is input along the longitudinal bridge, the axial force and shear force of the side pylon are much greater than those of the main pylon. When the seismic motion is input along the transverse direction of the bridge, the axial force, shear force, and bending moment of the main pylon are greater than those of the side pylon. The friction pendulum vibration reduction and isolation bearing is selected, and its designed initial vibration reduction and isolation capacity is 10% of the vertical bearing capacity. Under the E2 strong earthquake, the bearing enters the vibration reduction and isolation swing working state, which effectively extends the natural vibration period of the structure and realizes the vibration reduction and isolation design of the bridge. The setting of expansion joints should reserve the sufficient beam displacement to avoid the collision between the beam and the abutment during earthquakes. A viscous damper is installed between the abutment and the main beam, which can effectively control the longitudinal displacement of the beam body and the bridge pylon, and play a role in reducing vibration and energy consumption.