Nonlinear Dynamic Response and Seismic Performance of Steel Towers of Cable-Stayed Bridges under Great Earthquake Ground Motion

采用基于全拉格朗日公式的有限元方法，对三维大地震动作用下的钢塔斜拉桥进行了非线性动力分析。从调查和讨论中，可以总结出以下结论。(1)确定了水平梁位置对塔轴力动力响应的有效性。水平梁高度由原塔向塔顶的变化减小了塔底的轴向压缩力和轴向拉伸力。(2)倒v型轴向力响应最大，最大轴向压缩力约为重力荷载的4.70倍，最大轴向拉伸力约为重力荷载的2.55倍。大的负反力使得在提升过程中地脚螺栓可能失效，需要考虑塔架的安全问题。(3)所提出的消能系统在降低屈服水平时，通过在塔水平梁处集中非弹性性能并保持结构其余部分的弹性性能，证明了其在减小结构单元力和控制塔最大位移方面的能力和有效性。在塔结构的设计中应考虑屈服后屈曲能力。(4)垂直地震动对阻尼方案的影响很大。瑞利阻尼在高频范围内更为有效，导致垂直地面运动对塔动力响应的影响较小。对于高层塔楼的保守非线性地震反应，可以推荐采用罗伊利阻尼。(6)低屈服钢材料主要通过材料滞回作用增加阻尼，随着水平梁的早期达到，塔体的柔度增加，塔体结构体系反映部分地震输入能量增加的能力增强。消能系统通过水平梁吸收能量是有效的。(7)大质量刚性基础激活输入地震动的高频平移运动，产生基础晃动响应。对基础拐角处竖向响应的主要贡献来自巨大的基础晃动，而不是竖向激励。研究发现，永久定居的意义不大。少

A finite element procedure based on total Lagrangian formulation for the nonlinear dynamic analysis of steel tower cable-stayed bridge under three dimensional great earthquake ground motion is carried out. From the peiformed investigations and discussions, the following conclusions can be summarized.(1)The effectiveness of the horizontal beam position on tower axial force dynamic response is assured. The change of horizontal beam height from that of the original tower toward tower top reduces the compressive and tensile axial forces at tower base.(2)The inverted V-type has the largest axial force response, where the maximum compressive and tension axial forces are about 4.70 and 2.55 times of the gravity loads, respectively. The large negative reaction makes the problem that the anchor bolts may fail in the lift up and the safety of the tower should be considered.(3)The proposed energy dissipation system demonstrates its capability and effectiveness in reducing structural dements force … More s and controlling tower maximum displacement through its capability achieving the concentration of inelastic behavior at tower horizontal beam and keeping the rest of the structure elastic behavior as yield level decreases. The post-yield buckling capacity should be considered in the design of tower structures.(4)The effect of vertical ground motion has highly dependence on damping scheme. The Rayleigh's damping is more effective in high frequency range, which leads to slightly effects of the vertical ground motion on tower dynamic response. The Royleigh's damping could be recommended for conservative nonlinear seismic response of high-rise towers.(6)The low yield steel material could add damping primarily by material hysteresis and increase tower flexibility as the horizontal beam early attains, in terms tower structural system ability to reflect a portion of earthquake input energy increase. The energy dissipation system become effective in energy absorption through the horizontal beam.(7)The massive rigid foundation actives the high frequency translation motion of the input ground motion and generates foundation-rocking responses. The predominant contribution to the vertical response at footing base corner from the massive foundation rocking rather than from the vertical excitation. The permanent settlement is found to be less significant. Less