【作者】 刘斌；

【导师】 沈锐利；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2009， 硕士

【摘要】 近年来,跨海以及跨江工程是桥梁工程的又一热点,三塔悬索桥方案已经在我国跨长江的两座桥中采用。三塔大跨悬索桥中,桥梁的抗震能力、抗风能力和车桥振动问题可能是设计中的控制因素。论文从能量原理出发建立三塔悬索桥自由振动的基本方程,利用Rayleigh-Ritz方法推导了三塔悬索桥竖向振动的四个基频计算公式和扭转振动的四个基频计算公式。然后以两个算例验证了该基频计算公式的正确性,并对相关因素的影响进行了讨论。论文建立主跨1,080m、结构体系不同的四个三塔悬索桥有限元计算模型,分析了冲击荷载作用于加劲梁多个不同位置时不同体系悬索桥加劲梁的挠度、加速度及内力、主缆张力、吊索张力、桥塔塔顶位移和桥塔塔底弯矩的振动响应特点;讨论了冲击荷载持时变化和有限元计算模型中阻尼取值变化对结构动力响应的影响。为了解冲击荷载作用下结构动力响应的频域特性,本文还对部分时程响应结果作了频谱分析,得到该类荷载作用下不同阶振型对结构综合动力响应贡献大小的规律。最后文章还考察了谐振荷载作用下结构的动力响应特性。为分析行车荷载通过三塔悬索桥时结构的动力响应,论文仍采用上面四个有限元模型,作了简单匀速移动荷载作用下结构的瞬态动力分析。计算分析了不同大小值的集中荷载以不同速度过桥时结构的内力、位移振动响应结果。为考虑车辆惯性力对车辆桥梁相互作用力的影响,论文同时讨论了有限元仿真计算中移动质量模型和移动荷载模型动力响应结果的差别。按一种较为简单的行车情况,本文模拟了相隔固定间距并以恒定速度前行的无限长车队依次通过三塔两跨连续悬索桥时结构的动力响应情况。更多还原

【Abstract】 Intercontinental engineering over sea and river become another hotspot in bridge engineering recently, and the proposal of three-tower suspension was put into practice by two bridges which are both over The Changjian River. The dynamic response of seismic vibrations,wind-induced vibration and vehecal load may be very important in the design of three-tower suspension bridge.Based on energy principles,the thesis firstly formed the inherent vibration formula of three-tower suspension bridge, and four vertical vibrating fundamental frequency and four torsional vibrating fundamental frequency of the bridge were deduced by the Rayleigh-Ritz method. Then the computation formulas were all verified by caculating two case.The thesis also discussed the related influencing factors which will influence the fundamental frequency result calculated by the formula.In the thesis, four different types finite element model of three-tower suspension bridge, of which main span are all 1,080 meters were established. The deflection, acceleration and internal force of stiffening girder, horizontal tension of main cable, tension of sling, longitudinal displacement in the top of tower and bending moment in the bot of tower respectively of the four model were analyzed in case that impact load acting on the different parts of stiffening girder. The time history responses of the structure were discussed when the duration of impact load and damping of computational model changed. It had also done frequency-domain analysis with time domain response results when impact load act on it,and so the relationship between inherent vibration mode and general dynamic response of the structrue had been revealed. At the end of chapter, simple harmonic loading were applied on the structure and its harmonic response was studied.The thesis analyzed the dynamic response of three-tower suspention bridge model when the simple traveling load moves on road, and internal force,deflection response of the structure were also computed and analyzed here,in case that the velocity or magnitude of traveling load was variable. Considering of vehiclular inertial force may also impact the interaction force between vehicle and bridges,the thesis also discussed the difference results of computational model based on moving loads and moving mass. At last,the thesis simulated a situlation that the equidistant indefinite length moving vehicle passed through the deck of three-span continous suspention bridge one after another,and the respond of it was studied.更多还原