With the increasing span of suspension bridges, the towers have higher heights and have become more flexible, and so do the nearby suspenders. Not only are the towers easy to be affected by winds, but also the nearby suspenders by the wake flow of the towers. To enhance the structural stiffness, a bridge tower may be designed with more columns, but this design may lead to strong aerodynamic interference among the columns, complicating the wind-induced behaviors of the tower and nearby suspenders. In this paper, wind tunnel tests and numerical simulations were carried out to investigate the vortex-induced vibration of a tall bridge tower with four columns, and the wake effects on nearby suspenders. The results show that the displacement response at the tower top increases with the increasing wind speed. No obvious lock-in region is observed, as different cross-sections of the tower show different vortex shedding characteristics. The vortex shedding characteristics are determined mainly by the aerodynamic forces acting on the leeward columns. In the wake of the tower, the aerodynamic forces of the suspenders have the same dominant frequencies as the shedding frequencies of the vortices from the tower. The frequencies may approach the natural frequencies of the suspenders, causing possible wake-induced vibration that should be avoided for a good design.

中文翻译：

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四柱高桥塔的涡激振动及其对附近吊杆的尾流效应

随着悬索桥跨度的增加，塔的高度越来越高，也越来越灵活，附近的吊杆也是如此。不仅塔容易受到风的影响，而且附近的吊杆也会受到塔的尾流的影响。为了提高结构刚度，桥塔可以设计更多的柱子，但这种设计可能会导致柱子之间产生强烈的空气动力干扰，使塔楼和附近吊杆的风致行为变得复杂。本文通过风洞试验和数值模拟研究了一座四柱高桥塔的涡激振动，以及尾流对附近吊杆的影响。结果表明，塔顶位移响应随着风速的增加而增加。没有观察到明显的锁定区域，由于塔的不同横截面表现出不同的涡旋脱落特性。涡旋脱落特性主要由作用在背风柱上的气动力决定。在塔的尾流中，吊杆的空气动力具有与塔的涡流脱落频率相同的主导频率。频率可能会接近吊杆的固有频率，从而导致可能的尾流诱发振动，这是一个好的设计应该避免的。吊杆的空气动力与塔的涡流脱落频率具有相同的主导频率。频率可能会接近吊杆的固有频率，从而导致可能的尾流诱发振动，这是一个好的设计应该避免的。吊杆的空气动力与塔的涡流脱落频率具有相同的主导频率。频率可能会接近吊杆的固有频率，从而导致可能的尾流诱发振动，这是一个好的设计应该避免的。