大跨度悬索桥桥塔尾流区吊索复杂风致振动

发布时间：2019-05-24 02:58

【摘要】：悬索桥利用了索结构抗拉强度高的特点,适用于建造超大跨度的桥梁。但是,连接主缆与加劲梁的吊索存在长细比大和阻尼小的特征,对风荷载敏感。在现场监测中发现,在悬索桥桥塔附近长度较大吊索在风作用下会发生大幅值振动,导致各股吊索发生碰撞。因此,研究桥塔附近长吊索的风致振动特征与致振机理,将为吊索的减振提供理论依据。本文主要研究内容如下:第一,吊点及其周围流场与吊索的振动密切相关,首先要研究桥塔周围流场特征。建立无吊索的桥塔绕流CFD模型,并监测吊点处风速。通过分析不同风向角下桥塔的气动力与吊点处风速的关系,发现吊点处风速与桥塔气动力的频率主导成分基本相同。第二,取桥塔附近两组吊索研究其风致振动的影响因素。吊索的振动由桥塔尾流、吊索相互干扰、碰撞共同作用,振动情况较复杂。利用动网格方法来控制吊索周围网格的变形与重构,通过“用户自定义函数”来控制吊索的振动及碰撞。当桥塔旋涡脱落频率与吊索的固有频率接近时,吊索将发生共振。在不同风向角下,桥塔尾流将一直影响第一组吊索的运动,吊索相互干扰作用对第二组吊索的作用更强烈。最后,根据模拟结果预测了三维吊索在桥塔尾流中的运动情况。第三,尝试在吊索外设置多孔套环来抑制吊索在桥塔尾流区的振动。吊索套环上的气孔沿圆周均匀布置,以适应不同的来流方向。当吊索的运动剧烈时,从套环气孔中吹出的气流速度较大,可以减小吊索尾流宽度,从而降低吊索的阻力。套环对吊索的横风向振动也由一定的削弱作用。
[Abstract]:The suspension bridge makes use of the high tensile strength of the cable structure and is suitable for the construction of large span bridges. However, the sling cable connecting the main cable and the stiffened beam has the characteristics of large slenderness ratio and small damping, which is sensitive to wind load. In the field monitoring, it is found that the large length sling near the suspension bridge tower will vibrate with large amplitude under the action of wind, which will lead to the collision of each sling cable. Therefore, the study of wind-induced vibration characteristics and vibration mechanism of long sling near the bridge tower will provide a theoretical basis for the vibration reduction of sling. The main contents of this paper are as follows: first, the flow field around the suspension point and its surroundings is closely related to the vibration of the sling cable. First, the characteristics of the flow field around the bridge tower should be studied. The CFD model of bridge tower flow around the tower without sling is established, and the wind speed at the hoisting point is monitored. By analyzing the relationship between the aerodynamics of the bridge tower and the wind speed at the hoisting point under different wind direction angles, it is found that the frequency dominant components of the wind speed at the hanging point are basically the same as those of the tower. Secondly, two groups of sling near the bridge tower are taken to study the influencing factors of wind-induced vibration. The vibration of the sling is complicated by the wake of the bridge tower, the interference and collision of the sling. The dynamic grid method is used to control the deformation and reconstruction of the grid around the sling, and the vibration and collision of the sling are controlled by "user-defined function". When the vortex shedding frequency of the bridge tower is close to the natural frequency of the sling, the sling will resonate. Under different wind direction angles, the wake of the bridge tower will always affect the movement of the first group of sling, and the interaction between sling and sling will have a stronger effect on the second group of sling. Finally, according to the simulation results, the motion of three-dimensional sling in the wake of bridge tower is predicted. Third, try to set up a porous ring outside the sling to restrain the vibration of the sling in the tail flow area of the bridge tower. The pores on the sling ring are evenly arranged along the circumference to adapt to different incoming directions. When the movement of the sling is fierce, the velocity of air blowing from the hole of the ring is large, which can reduce the wake width of the sling and thus reduce the resistance of the sling. The transverse wind vibration of the sling is also weakened by the ring.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441.3;U448.25

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