MR阻尼器对斜拉索减振控制的数值仿真

为控制斜拉索的大幅振动,在Hamilton原理基础上应用Galerkin法建立了斜拉索振动控制的计算模型。通过改进形函数,采用四阶五级RK算法对钱江三桥南岸154 m长的斜拉索进行了现场试验的数值仿真。磁流变(MR)阻尼器力学关系采用由室内试验结果回归的非线性滞回双粘性数学模型,系统等效阻尼比通过希尔伯特变换识别。分析表明:数值仿真对现场试验具有很好的指导作用,同时能进一步验证现场试验的结果。MR阻尼器作为被动控制器件时制振效果明显,与最优油阻尼器控制效果相当且控制的频域范围要比油阻尼器的广;当供电失效时也可满足斜拉索减振的要求。斜拉索的各阶共振峰频率在安装MR阻尼器后略微增大。MR阻尼器在施加一合适的电压时可以发挥最佳的制振效果。

Numerical Simulation of Vibration Control for Stay Cable Using MR Dampers

In order to overcome long span cables vibration,a calculation model for the cable-damper system was formulated by Galerkin method based on the Hamilton principle.The motion of the cable was computed by using a finite series approximation with a Galerkin method.Runge-Kutta method was applied for the numerical solution of initial value problems with oscillating solutions.A static deflection shape was taken as an addition shape function to improve the sine series convergence.According to experimental set-up,the 154 m long cable in the 3th Qianjiang Cable Stayed Bridge was numerical calculated.A nonlinear hysteretic bi-viscous model was identified for MR dampers.The displacement signal at observation point was driven by harmonic planar loads,and transformed by Hilbert.The equivalent cable modal damping ratios attributed to MR dampers were predicted,and the relationship among the equivalent modal damping ratios,the system frequency,the voltage imposed and displacement responses at the point of cable was pursued.The phenomena and conclusions from simulation guiding the experimental operation could be certified by full scale experimental study.It is shown that MR dampers to the cable can more significantly reduce cable vibration than oil dampers do;the resonant frequencies of the cable with MR dampers have a little increased change;there is optimum voltage on which the maximum modal damping ratio can be achieved.