在役斜拉索粘滞阻尼器力学性能与控制效果研究

Research on Mechanical Property and Control Effects of In-Service Viscous Dampers for Stay Cables

针对在役斜拉索粘滞阻尼器长期服役后易产生液体泄漏的问题,采用性能试验和有限元法定量评估并分析液体泄漏对阻尼器力学性能和减振控制效果的影响。首先,采用性能试验的方法分析实桥液体泄漏粘滞阻尼器力学性能,研究滑移产生的机理;然后,引入缝隙单元并与粘壶单元串联,建立液体泄漏粘滞阻尼器力学模型,确定模型参数并通过试验验证;最后,基于该力学模型,采用数值模拟方法建立斜拉索-液体泄漏粘滞阻尼器的系统模型,分析液体泄漏对斜拉索附加模态阻尼比的影响。结果表明:液体泄漏导致粘滞阻尼器阻尼力滞回曲线出现明显的滑移现象;液体泄漏后粘滞阻尼器内部出现空隙,当活塞杆经过空隙时无法产生正常的阻尼力,导致阻尼力滞回曲线出现滑移平台,显著削弱了阻尼器的耗能能力;随着滑移量的增大,粘滞阻尼器能够实现的一阶附加模态阻尼比逐渐减少,降低了其对斜拉索的减振控制效果。

After long-term service,viscous dampers of stay cables are prone to liquid leakage.This article quantitatively evaluates and analyzes the degradation of mechanical property and vibration control performance of viscous dampers caused by liquid leakage.Firstly,using performance testing methods,viscous dampers with liquid leakage on an existing bridge are selected to study their mechanical properties and explore the mechanism of slip generation.Secondly,the mechanical property of the viscous dampers with liquid leakage was numerically simulated,with the gap elements and dashpot elements connected in series.The parameters of the model were determined and verified by tests.Based on the mechanical model,the system model of stay cables and viscous dampers with liquid leakage was established to analyze the slip triggered by liquid leakage on the additional damping ratio of the stay cables.It is shown that the liquid leakage caused significant slip of the hysteresis curves of the damping forces of the viscous dampers attached to the in-service stay cables in the second and fourth quadrants.There appeared gap inside the viscous dampers after liquid leakage,and when the piston rod passes by the gap,no resistance was generated,as a result,there appeared slip platform in the hysteresis curve of the damping force,which distinctively weakened the energy dissipation capacity of the dampers.As the slip increases,the first-mode additional damping ratio became smaller,undermining the vibration control effect of the viscous dampers on the stay cables.