桥梁自立杆风致振动TMD控制及优化设计

TMD CONTROL AND DESIGN OPTIMIZATION FOR WIND INDUCED VIBRATION OF A SELF-STAYED ROD ON A BRIDGE

桥梁自立杆风致振动往往会引起路灯及附属监测设施的损坏,严重时甚至导致灯杆断裂,对其进行风振控制可以避免因常年设施检修引起交通不畅等庞大间接损失。采用TMD阻尼器进行自立杆振动控制已有工程应用,然而相应的阻尼器参数优化设计方法尚未得到深入的研究。根据频域分析理论,采用虚拟激励法及詹姆斯公式可以得到安装TMD阻尼器前后的等效阻尼比,通过参数分析得到了阻尼器参数及位置对控制效果影响的优化曲线,采用该曲线就可以得到TMD的最优参数及安装位置。还推导并建立了自立杆-阻尼器系统的耦合风振控制方程,可适用于Newmark-β时程分析方法。选择某一实际桥梁路灯杆,根据优化曲线选取并安装TMD阻尼器,风荷载则采用谐波合成法模拟脉动风速叠加平均风速计算获得,时程分析表明采用TMD阻尼器并结合提出的优化设计方法极大地抑制了自立杆的振动。时域与频域分析结果比较表明二者吻合较好,说明自立杆振动可以采用考虑一阶振动的频域分析结果。

Wind induced vibration of a self-stayed rod on a bridge will cause damage of lamps and monitoring instruments on the rod,even lead to its being broken.Tuned mass dampers(TMD) are applied in actual vibration control of rods,but deep study on design and optimizing damper parameters and location are not conducted.According to the frequency domain analysis theory,the virtual excitation method and James formulation are used to obtain the equivalent damping ratio before and after installation of TMD damper.Through parameter analysis,an optimal design carve reflecting effects of damper parameters and locations on vibration control efficiency is obtained.With it,optimal parameters and location of a TMD can be achieved.The couple vibration equation of the damper-rod system is derived,which is appropriate for Newmark-β time domain analysis.An actual lamp rod on a bridge is selected for case study with a TMD installed,its parameters and location are chosen based on the optimal design curve.After simulating wind load with weighted amplitude wavelet superposition(WAWS) method,time domain analysis is also conducted.It is indicated that the vibration of the rod on the bridge is obviously suppressed using a TMD.Comparison of the results obtained in time and frequency domain shows that they agree well each other,and the frequency domain results considering just one vibration mode can be used for the rod vibration analysis with relative small error.