【作者】 王中正；

【导师】 安永辉；

【作者基本信息】 大连理工大学 ， 结构工程， 2019， 硕士

【摘要】 吊杆是大跨度桥梁中最脆弱的部件之一,其在正常服役状态下的持续的振动响应会引起疲劳累计甚至导致构件损坏;以往的研究表明,在极端天气下吊杆可能发生的大幅振动,会对桥梁结构和交通安全构成威胁。到目前为止,垂直吊杆的减震研究还较为有限,但近年来逐渐引起学者和工程师们的重视。本研究着眼于大跨桥梁细柔吊杆的振动控制,研究了使用两种被动控制手段对其实现减振:环形调谐液体阻尼器与摆式调谐质量阻尼器,并给出了相应的设计方法、模拟与实验验证,并对其模拟结果进行了对比。本文主要研究内容如下:(1)本文中提出了运用于吊杆减振的环形调谐液体阻尼器(RSTLD)。基于SIMULINK对吊杆-阻尼器体系分别进行了正弦荷载与白噪声荷载激励下的数值模拟,研究了阻尼器尺寸等参数的优化设计方法,探讨了阻尼器尺寸与其阻尼比对减振效果的影响,并给出了该方法适用的吊杆频率范围。选取大连星海湾跨海大桥的一根长度为61.55m的吊杆作为现场实验研究对象,对RSTLD的控制效果进行验证。加工了考虑不同质量比和充填液体(分别为水与甲基硅油)的两个RSTLD进行实验,采集了安装阻尼器吊杆的响应与没有安装阻尼器的在另一吊杆平面上的对称吊杆的响应进行对照,用于在受控和非受控情况之间进行比较。实验结果表明,当液体为水且质量比为3%时,安装RSTLD后吊杆中点的加速度方差和最大加速度分别降低约50%和20%~30%。当充填甲基硅油的质量比为1%时,加速度方差和最大加速度分别降低约30%和20%。实验中的振动控制效果接近于模拟中的效果。在一定范围内,如果调整更大的液体粘滞阻尼比或更大的质量比,则振动控制效果将增加。(2)提出了一种四线摆式的摆式调谐质量阻尼器(PTMD)。文章中探讨了所提出的PTMD的运动机理,四线悬吊摆运动中的摆长变化和其在大摆角下的非线性对悬吊摆周期的影响;并且探究了其在不同的荷载幅值下的摆动幅度情况;通过模拟探讨了质量比和摆长等因素对控制效果的影响;提出的PTMD对于吊杆的位移和速度具有良好的控制效果,相同的质量比下优于环形调谐液体阻尼器,但对于吊杆加速度的控制效果有限。该研究提出的两种阻尼器对于桥梁吊杆所有方向的振动均具有良好的减振效果,可减轻在恶劣的外部环境下桥梁结构承受的反复的大小和方向不断变化的动力荷载对桥梁吊杆的安全服役造成的负面影响,其研究成果或将在工程上取得重要的应用并对于提高细柔构件服役寿命以及减轻维护吊杆的负担有积极的意义。更多还原

【Abstract】 A growing number of long span bridge is and will to be in service.The suspender cable is one of the most vulnerable components in long-span bridges.Vibration of the suspender cables will induce fatigue damage under common serice state,and large vibrations of these cables under extreme weather can be a threat to traffic and structural safety.The studies about the suspender cable is attracting more and more attention nowadays.This study focuses on the vibration of suspender cable,and it is imperative to develop effective methods to mitigate such vibration.Two methods are mentioned in this paper: ring-shaped tuned liquid damper and pendulum-tuned mass damper,with relative design methods,simulation and validation.The main research contents of this paper are as follows:(1)A ring-shaped tuned liquid damper(RSTLD)for vibration mitigation of suspender cable is proposed in this paper.The study utilizes SIMULINK environment to numerically simulate the structure-RSTLD system.A 61.55 m long suspender cable of the Xinghai Bay Cross-sea Bridge was selected as the object of the field experiment to verify the RSTLD’s vibration control efficiency.Two RSTLDs with different mass ratios and filled liquids were adopted in the experiment,and the response of the RSTLD installed cable and the symmetrical cable on the other cable plane without damper was acquired for comparing controlled and uncontrolled conditions.The experimental results show that when the liquid is water and the mass ratio is 3%,the variance of the acceleration and the maximum acceleration is reduced by about 50% and 20% to 30%,respectively.When the liquid is silicone oil and the mass ratio is 1%,the variance of the acceleration and the maximum acceleration is reduced by about 30% and 20%,respectively.The vibration control effect in the experiment is close to that in simulation.If a larger liquid viscosity damping ratio or a larger mass ratio is used,the vibration control effect will increase.(2)A pendulum-tuned mass damper(PTMD)in the form of a four-wire pendulum is proposed.In this paper,the motion mechanism of the proposed PTMD is discussed and the four-wire suspension pendulum model considering the nonlinear and pendulum length changes under the large swing angle is analyzed;explore the swing amplitude under different load amplitudes;discuss the influence factors upon the mitigation effect;the simulation results show that PTMD has great damping effect on the displacement and velocity index of the response,but there is limit effect upon the acceleration..The two damper both have a good damping capacity for all excitation directions,and can alleviate the negative impact upon the bridge structure suspender cable’s safe service caused by loading which repeat changes in magnitude and orientation in the harsh external environment.Research results may have important applications in engineering and have a positive impact on improving the service life of the delicate components and reducing the burden of maintenance and maintenance of suspender cable.更多还原