【作者】 邬喆华；

【导师】 唐锦春； 楼文娟；

【作者基本信息】 浙江大学 ， 结构工程， 2003， 博士

【摘要】 本文采用MR阻尼器对斜拉索振动的控制进行了试验和理论研究，系统深入地分析了MR阻尼器对斜拉索的减振效果。 本文以钱江三桥南岸154m长的斜拉索为试验对象，通过施加阶跃荷载的方法获得斜拉索在MR阻尼器施加不同电压情况下前三阶振动的自由衰减信号。采集到的信号采用小波分解进行滤波，并经Hilbert变换识别出系统的等效阻尼比。试验结果表明MR阻尼器作为被动控制器件时存在最优电压；制振效果明显优于试验中的油阻尼器，控制的频域范围比油阻尼器更宽广；当供电失效时系统仍有较大的等效阻尼比，可以满足对索减振的要求；索的各阶共振峰频率在安装MR阻尼器后发生稍许增大，其影响程度比安装油阻尼器时明显。在Hamilton原理基础上应用Galerkin法，改进形函数的选取，建立了斜拉索振动控制的数学模型。对试验索和MR阻尼器组成的系统进行了数值振动计算，由此验证了试验结果。在Spencer现象模型的基础上研究了MR阻尼器的最优参数(型号、安装位置、施加的电压)以及斜拉索基频(张力、索长、质量)、Irvine参数、激励荷载(类型、频率、大小)等各种因素对MR阻尼器制振效果的影响。采用全索位移RMS作为评价MR阻尼器对斜拉索减振效果的指标，并与最优粘性油阻尼器进行了比较。计算结果表明存在合适的MR阻尼器(最优的MF)使斜拉索的减振效果达到最佳，并与粘性油阻尼器的最佳减振效果相当。以斜拉索共振峰频率漂移评价了MR阻尼器对系统提供的附加等效刚度。理论分析进一步丰富完善了试验所取得的成果，为MR阻尼器被动控制的实施提供了优化设计的方法。按照减振效果位移RMS等价的原则提出了用于MR阻尼器被动控制的简化模型。大量计算结果表明简化模型不仅与Spencer现象模型有极为相似的减振效果，能满足MR阻尼器被动控制的要求；而且能更好地揭示MR阻尼器的制振原理。等效粘性阻尼系数和等效刚度系数是表征MR阻尼器力学性能的重要指标。MR阻尼器被动控制的等效阻尼统—曲线表明MR阻尼器与粘性油阻尼器存在共性，均为耗能器件；而施加电压、激振频率、动力响应的幅值对MR阻尼器耗能能力的影响表明MR阻尼器制振效果更易适应外界环境的变化。采用偏最小二乘法误差估计、Chebyshev多项式拟合建立了MR阻尼器简化模型的参数化表达式，为合理选择MR阻尼器提供了便捷的可靠的手段。 本文提出了基于位移和速度方向的半主动控制算法；并将多种主动控制算法(线性最优控制算法、特征结构配置法、次最优控制法、变结构滑移模态控制法)与施加电压的切换方法(剪切优化控制法、基于阻尼器出力和速度法和基于Lyapunov稳定理论法)有机结合，发展了基于最优控制力的半主动控制算法。浙江大学博l了学位论文磁流变阻尼器对斜拉索振动控制的研究考察了MR阻尼器型号、安装位置、斜拉索基频(张力、索长、质量)、激励荷载(类型、频率、大小)等各种因素对MR阻尼器半主动制振效果的影响。研究表明MR阻尼器型号在合适的范围内对斜拉索半主动控制的减振效果优于最优的被动控制、优于最优的粘性油阻尼器，但弱于理想的半主动可变阻尼器减振性能。对长索亦能取得较好的减振效果。在基于位移和速度方向的半主动控制算法控制下MR阻尼器的最优型号与被动控制的最优型号接近。该算法在现场中只需在阻尼器处设置一个观测器就能完成实时控制，算法简单，易于操作，安全可靠，鲁棒性好，制振频域宽广。 在试验和理论研究的基础上开发出斜拉索振动控制分析软件MRCONTROL。该软件能完成MR阻尼器作为被动控制和在上述各种半主动控制算法下的分析计算，可与粘性油阻尼器的控制效果进行比较。通过MATLAB软件转化，可以在控制试验设备DSPACE系统上实现实时现场控制。更多还原

【Abstract】 Considering an extremely economic design and an aesthetic view to human being, cable-stayed bridges are practiced widely in longer spans. As the most important structural components in cable-supported bridges, stay cables, however, are vulnerable to vibrations with large amplitudes due to relate small mass, low internal structural damping and high flexibility. A number of methods have been proposed to mitigate cable vibrations, such as tying cables together, aerodynamic cable surface modification, passive and semi-active cable control have been used to dampen vibration. However, each has limitations in suppressing the longer cable vibration. As semi-active control devices, magneto-rheological (MR) dampers have significant potential to advance the acceptance of structural control as a viable means for dynamic hazard mitigation. This thesis focuses on the field of control of cable vibration by using MR dampers. Main conclusions are as follows:Considering that the field experimental study of bridge stay cables installed MR dampers is lack and different passive vibration controls have not compared in the same experiment, the discrete MR dampers were installed on the 154m-Iong cable near the anchorage in the 3rd QianJiang cable-stayed bridge. Vibration mitigation of the cable using MR dampers in a purely passive mode, where constant levels of current are supplied to the damper, is examined by a series of free vibration tests and compared to that of using oil dampers. The displacement signal is driven by harmonic planar loads, filtered through wavelet decomposition and transformed by Hilbert. The equivalent cable modal damping ratios attributed to MR dampers were measured and the relationship between the equivalent modal damping ratios, the system frequency, the voltage imposed and displacement responses at the point of cable was pursued. It is shown that MR dampers to the cable can more significantly reduce cable vibration than oil dampers do. There is optimum voltage on which the maximum modal damping ratio can be achieved.A theoretical model for the cable damper system is formulated by accounting for the cable inclination and sag effect based on the Hamilton’s principle. The motion of the cable was computed by using a finite series approximation with the Galerkin method. A static deflection shape as an addition shape function improved the sine series convergence. The experimental cable is taken as an numerical example. A nonlinear hysteretic biviscous model is identified for MR dampers according to experiment. The results also show the similar phenomenon and conclusions from experiment.A stay cable incorporated with MR dampers exhibits pronounced nonlinearity. The dynamic response performances of a cable with MR dampers are explored indetail by using Spencer photometric model. The primary measure of damper performance considered is the root mean square(RMS) cable deflection integrated along the length of the cable and the whole time. A universal estimation approach has been configured to depict the relationship among the equivalent modal damping ratio, RMS cable deflection, the optimal parameter of MR dampers (marker, mounting position and voltage applied), the first frequency of cables (tensile force, length and mass per unit length), Irvine parameter, excited loads (type, frequency and amount). The mitigation effect of the first three modal vibration of the cable was compared to the optimal oil dampers do. Frequency shift also debated. The theoretical studies rich and perfect the experimental results, and supply an optimal method for passive MR damper in practice.Based on equivalent RMS cable deflection criteria, the simplifying model is established for MR damper passive control. The calculated results shown that the simplifying model not only has the similar effect of mitigation to the Spencer model but also reveal the laws of energy dissipation criteria for MR dampers much better. The equivalent viscous damping coefficient and the equivalent stiffness coefficient capture the salient features of M更多还原