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为了研究材料非线性和竖向地震动对长挑臂宽主梁斜拉桥地震响应的影响,分别按照弹性梁单元和弹塑性纤维单元建立了全桥有限元模型,采用非线性时程反应方法,对比分析了该桥的动力特性和地震响应。研究表明:弹性模型的各阶周期明显大于纤维模型,且两者对应的振型出现在不同的阶数;不管峰值加速度(PGA)大小如何,弹性模型都会大大高估主塔的地震内力响应,低估其位移响应,且PGA越大,误差也越大;竖向地震动对主塔纵桥向的地震响应影响较大,对横桥向影响很小;随着PGA的增大,竖向地震动的影响也越大,不仅会大幅增大主塔的内力响应,而且会改变主塔的位移分布规律。因此,长挑臂宽主梁斜拉桥的抗震分析必须同时考虑材料非线性和竖向地震动的影响,尤其当PGA较大时。
In order to study the influence of material nonlinearity and vertical ground motions on the seismic responses of cable-stayed bridges with long picks and legs, a full-bridge finite element model was established according to elastic beam elements and elastoplastic elements respectively. Nonlinear time-history methods , Comparative analysis of the dynamic characteristics of the bridge and seismic response. The results show that the elasticity of the elastic model is obviously larger than that of the fiber model, and the corresponding vibration modes appear in different orders. The elastic model will greatly overestimate the seismic response of the main tower regardless of the peak acceleration (PGA) The displacement response is underestimated, and the bigger the PGA is, the bigger the error is. The vertical ground motion has a great influence on the seismic response of the longitudinal tower of the main tower and has little effect on the transverse bridge. As the PGA increases, the vertical earthquake The greater the impact of moving, not only will greatly increase the response of the main pylon internal force, but will change the main tower displacement distribution. Therefore, the seismic analysis of cable-stayed bridge with long arm and wide beam must take into account both the material nonlinearity and vertical ground motions, especially when the PGA is large.