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

基于全拉格朗日公式，建立了钢塔斜拉桥在三维大地震作用下的非线性动力分析的有限元程序。通过前期的研究和讨论，得出以下结论：(1)保证了水平梁位置对塔架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基的压拉轴力。(2)倒V型结构的轴力响应最大，最大压拉轴力分别约为重力荷载的4.70倍和2.55倍。较大的负反力使得地脚螺栓在吊装过程中可能失效，必须考虑塔架的安全性。(3)消能减震体系在降低结构维向力…方面具有一定的能力和有效性。更多的是通过S和控制塔架最大位移的能力，实现了塔架水平梁处弹塑性行为的集中，并保持了结构其余部分的弹性行为随着屈服水平的降低。塔楼结构设计时应考虑屈曲后的屈曲能力。(4)竖向地震动的影响与减震方案有很大的相关性。瑞利阻尼器在高频段更有效，这导致竖向地面运动对塔楼动力响应的影响很小。对于高层塔楼的保守非线性地震反应，建议采用Royleigh阻尼法。(6)低屈服钢材料主要通过材料滞回来增加塔架的阻尼力，随着横梁的提早达到，塔架的柔度也随之增加，这是因为塔架结构体系能够反映一部分地震输入能量的增加。耗能体系通过横梁起到有效的吸能作用。(7)大体积刚性基础激发输入地震动的高频平移运动，产生基础摇摆反应。对基础底角竖向响应的主要贡献来自于大体积基础的摇摆，而不是竖向激励。永久解决方案被发现没有那么重要。较少

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