考虑桥墩轴力变化影响的刚构桥近场地震反应

为了分析刚构桥梁顺桥向近场地震反应特性,通过对远场地震时程叠加三角函数拟合速度脉冲的方法模拟近场地震动,根据纤维及塑性铰2种计算模型在近场地震作用下弹塑性地震反应计算结果讨论地震动脉冲对中等规模刚构桥梁地震反应的影响.结果表明,刚构桥梁在地震作用下桥墩轴力变化较大,采用纤维模型计算时桥墩地震反应较大|近场脉冲型地震激励下,桥梁地震反应与脉冲持时有关,短周期脉冲对本桥地震反应影响较大.采用叠加速度脉冲的方法模拟近场地震是可行的方法.

Seismic response of rigid frame bridge subjected to near-fault ground motion with effect of axial force variation of pier

The velocity pulses which simulated by trigonometric functions were superimposed on far-fault ground motions to simulate the near-fault ground motions. Based on elastoplastic seismic response of fiber model and plastic hinge model subjected to near-fault ground motion, the influence of ground motion pulse on seismic response of medium-sized rigid frame bridge were studied. The results show that the axial force of rigid frame bridge pier change obviously in the earthquake, and the seismic response of pier more significant when fiber model is used; the seismic response of bridge subjected to near-fault ground motion is related to the pulse duration, and the influence of short-cycle pulse to seismic response of the bridge is more obvious. The method of superimposing velocity pulse to simulate the near-fault ground motions is reasonable．