基于TMD的大跨度悬索桥时域抖振控制研究

发布时间：2018-11-27 20:42

【摘要】：随着现代交通工程对跨线结构设计要求的不断提高,新建桥梁逐渐向大跨、纤细、轻柔的特点发展,作为跨越能力相对较强的悬索桥体系,自然风下主梁的抖振问题随之凸显,结构在长周期下的疲劳振动将大大缩短其正常服役年限。因此,对大跨度悬索桥风致抖振控制措施进行系统研究显得十分必要。当前针对结构制振问题的研究已存在多种控制方法,而调谐质量阻尼器(Tuned Mass Damper,简称TMD)是运用于桥梁上最为广泛的机械减振被动控制手段之一。本文以国内某大跨度悬索桥为工程背景,采用数值模拟的方式研究了该桥在脉动风下的主梁横向及竖向时域抖振响应,结合TMD减振原理后,对主梁节点的振动位移及加速度等关键指标进行了控制。通过研究工作主要得出以下结论:1、采用乔列斯基分解法获得自然风的随机样本,通过ANSYS二次开发语言(APDL)实现了脉动风荷载(抖振力)向桥梁结构的输入及求解。对比结构自振特性及时域抖振模拟结果后发现,主梁的随机振动形态以基阶横弯及竖弯模态占主导,针对本桥的TMD参数设计应基于最大频响值下的发振频率。2、采用ANSYS自带单元联合模拟了线性减振TMD装置,结合被控结构在时域下的抖振均方根分布(RMS)及频域下的幅值谱响应,对STMD(Single Tuned Mass Dampers)的设计参数进行了初步确定,采用正交试验方法对各参数的敏感性进行了分析,研究表明,STMD减振效果不随质量及刚度的改变单调变化,阻尼系数的增大有利于结构减振性能的提高。3、由于本桥固有频率较低,在进行TMD控制时提取了 TMD节点及对应主梁节点的相对位移时程,结合弹簧减振原理后发现本桥TMD存在过大初始静位移且与自身质量无关,本文借鉴实际工程下减振弹簧的预压技术解决了数值模拟中竖弯振动在控制初期振幅过大的问题。4、调整STMD的频率参数对桥梁进行了前两阶模态的调谐控制,研究发现竖向振动控制在同时考虑前两阶模态振型的参与时较横向制振效果更为明显。因此,实际工程应用中STMD的设计应基于被控结构的激振频率及对应频响程度来进行参数的确立。5、采用MTMD(Multiple Tuned Mass Dampers)对本桥进行了减振控制模拟,通过对减振装置自身参数及主梁结构固有频率的偏移调整发现,作者针对本桥提出的MTMD参数取值具有一定程度的结构老化适应性,其设计频带宽可适用于该桥的长周期服役。
[Abstract]:With the increasing demands of modern traffic engineering on the design of cross-line structure, the newly built bridges are gradually developing to the characteristics of long span, slender and soft. As a suspension bridge system with relatively strong span ability, the buffeting problem of the main girder under natural wind becomes prominent. The fatigue vibration of the structure under long period will greatly shorten its normal service life. Therefore, it is necessary to study the wind-induced buffeting control measures of long-span suspension bridge. At present, there are many control methods for vibration control of structures, and tuned mass damper (Tuned Mass Damper,) is one of the most widely used passive control methods of mechanical vibration reduction in bridges. In this paper, the transverse and vertical time domain buffeting responses of the main beam of a large span suspension bridge under pulsating wind are studied by numerical simulation based on the engineering background of a large span suspension bridge in China. After combining with the principle of TMD vibration reduction, The key indexes such as vibration displacement and acceleration are controlled. The main conclusions are as follows: 1. By using Cholesky decomposition method, the random samples of natural wind are obtained, and the input and solution of pulsating wind load (buffeting force) to bridge structure are realized by ANSYS secondary development language (APDL). By comparing the natural vibration characteristics of the structure and the time domain buffeting simulation results, it is found that the random vibration patterns of the main beam are dominated by the fundamental transverse bending and vertical bending modes. The design of TMD parameters of the bridge should be based on the frequency of the maximum frequency response. 2. The linear damping TMD device is simulated by ANSYS self-contained unit. The design parameters of STMD (Single Tuned Mass Dampers) are preliminarily determined by combining the buffeting RMS distribution (RMS) of the controlled structure in time domain and the amplitude spectrum response in frequency domain. The sensitivity of each parameter is analyzed by orthogonal test. The results show that the damping effect of STMD does not change monotonously with the change of mass and stiffness, and the increase of damping coefficient is beneficial to the improvement of the damping performance of the structure. Because of the low natural frequency of the bridge, the relative displacement time history of the TMD node and the corresponding main beam joint is extracted during the TMD control. Combined with the principle of spring vibration absorption, it is found that the TMD of the bridge has excessive initial static displacement and is independent of its own mass. In this paper, the problem of excessive amplitude of vertical and flexural vibration in numerical simulation is solved by using the preloading technique of damping spring in practical engineering. 4. The first two modes of bridge are tuned by adjusting the frequency parameters of STMD. It is found that the vertical vibration control is more effective than the transverse vibration control when the first two modes are taken into account simultaneously. Therefore, in practical engineering application, the design of STMD should be based on the excitation frequency and the corresponding frequency response degree of the controlled structure to establish the parameters. 5. The vibration control simulation of the bridge is carried out by using MTMD (Multiple Tuned Mass Dampers). Through the offset adjustment of the vibration absorber's own parameters and the natural frequency of the main beam structure, it is found that the MTMD parameter values proposed by the author have a certain degree of structural aging adaptability, and its design frequency bandwidth can be applied to the long period service of the bridge.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441.3;U448.25

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