相近参数拉索的同/异步振动特性研究

辅助索被认为是一种具有潜力的减振手段,但仅在拉索间发生异步振动时才能取得良好的效果．然而,目前对拉索同/异步振动机理尚缺乏系统研究,为此对双水平索进行了模型试验研究．试验主要关注两根不同垂跨比水平拉索跨中面内响应的相位关系．首先对模型进行不同激励频率和保持激励幅值不变下的振动测试,发现垂跨比相同时,两根索相位差基本保持一致;垂跨比不同时,两根索由同步振动转为异步振动．同时采用有限元软件模拟测试实验,其结果与实验吻合良好．为更进一步探究其机理,对试验模型进行了相同激励幅值下的扫频试验．通过对双索幅频特性和相频特性的分析,发现拉索相近参数导致共振区错位是双索存在异步振动现象的根本原因．

Study on Synchronous/Asynchronous Vibration Characteristics of Cables with Similar Parameters

Cross-tie is considered to be a potential means of vibration reduction, and can only achieve good effect when asynchronous vibration occurs between cables. However, there is still a lack of systematic research on the mechanism of synchronous/asynchronous vibration of cables, therefore the model experiment of double-horizontal cables was carried out. The experiment was mianly concerned about the phase relationships of in-plane responses of two horizontal cables with different sag-span ratios. Firstly, the vibration experiment of the model was carried out under different excitation frequencies and constant excitation amplitudes. It was found that the phase difference of the two cables was basically the same when the sag-span ratio was the same, while the two cables changed from synchronous vibration to asynchronous vibration when their sag-span ratio was different. At the same time, finite element software was used to simulate the experiment, and the results were in good agreement with the experiment. In order to further explore the mechanism, the sweep-frequency test was carried out for the experiment model under the same excitation amplitude. Through the analysis of the amplitude-frequency characteristics and phase-frequency characteristics of double cables, it is found that the mismatch of the resonance range caused by the similarity of the cable parameters is the fundamental reason for the existence of asynchronous vibration of double cables.