近海环境斜拉索风致疲劳损伤的磁流变阻尼器控制

Long span cables are susceptible to vibration with large amplitude under wind/rain loading, vehicles or support excitation due to their light weight, small damping ratio and internal flexible. The durability of cable structures is affected by the fatigue damage that accumulates within service time. This project is focused on stay-cables in the offshore environment. Magneto rheological dampers (MR dampers) are applied in control of cables vibration induced by wind in order to decreasing the fatigue damage caused. The mechanism of stay-cable random vibration is examined and fluid-structure interaction of wind vibration mathematical model is built. The structural system combined the main tower, cables, dampers and the deck is done with nonlinear dynamic analysis. Applied with vibration control equations discrete and numerical methods of optimization, the dynamic response of the cables are required. The MR damper model is established by identified test parameters. According to the field of ocean wind environment test, the relationship between the optimal marker of the MR dampers, the mounting position, the voltage applied, the first frequency of the cables (tensile force, length, and mass per unit length), lag time exciting loads with the fatigue damage in key points of stay-cables are studied. Experimental study of indoor cable-stayed model and the engineering of cables are planned. Vibration control of MR dampers are compared with other control method (passive control, aerodynamic damping method, auxiliary rope method). Semi-active control strategies which are based on the displacement and velocity direction and based on optimal control are advanced to improve structural safety of the cross sea bridges.

斜拉索质量轻、阻尼小、柔性大，极易在风、雨、车辆、支座激励等外界因素作用下产生不同机理的大幅振动，由此引发的疲劳损伤将影响拉索结构的耐久性能。本项目研究超长斜拉索在近海环境下应用磁流变阻尼器控制风致振动，抑制其疲劳损伤的发生。根据斜拉索随机振动的作用机理，建立风致疲劳损伤数学模型，优化振动控制方程的离散和数值计算方法，分析主塔-斜拉索-阻尼器-桥面耦合振动的非线性动力响应。通过磁流变阻尼器力学模型的试验参数识别，现场实测近海风环境，试验研究室内索模型和工程索，考察磁流变阻尼器型号、安装位置、安装方式、斜拉索基频、激励荷载、半主动控制算法、控制的滞后时间等各种因素对斜拉索关键受力部位抗疲劳损伤的影响，结合与其它控制方法（阻尼器被动控制、气动减振法、辅助索法等）抗疲劳损伤的比较，完善基于位移和速度方向和基于最优控制力的两种半主动控制算法，提高跨海大桥整体结构的安全度。

斜拉索质量轻、阻尼小、柔性大，极易在风、雨、车辆、支座激励等外界因素作用下产生不同机理的大幅振动，由此引发的疲劳损伤将影响拉索结构的耐久性能。本项目研究超长斜拉索在近海环境下应用磁流变阻尼器控制风致振动，抑制其疲劳损伤的发生。根据斜拉索随机振动的作用机理，建立风致疲劳损伤数学模型，优化振动控制方程的离散和数值计算方法，分析被控系统振动的非线性动力响应。通过建立磁流变阻尼器力学模型，模拟近海风环境，分析研究了索模型和工程索，考察磁流变阻尼器型号、安装位置、安装方式、斜拉索基频、激励荷载、半主动控制算法、控制的滞后时间等各种因素对斜拉索关键受力部位抗疲劳损伤的影响，结合与其它控制方法（阻尼器被动控制、气动减振法、辅助索法等）抗疲劳损伤的比较，完善基于位移和速度方向和基于最优控制力的两种半主动控制算法，提高跨海大桥整体结构的安全度。