拱桥钢箱吊杆驰振稳定性数值计算研究

Numerical Calculation of Galloping Stability of Steel Box Suspender of Arch Bridge

驰振是细长结构在横风向作用下的一种不稳定的单自由度发散振动现象,会导致结构毁坏,截面形状的微小变化会改变结构驰振稳定性.文中运用两种方法对南京大胜关长江大桥吊杆1/10缩尺模型进行了驰振性能计算,并展示了驰振中的极限环振动现象.吊杆包括长方形截面、切角长方形截面A、切角长方形截面B三种方案.方法一是通过计算流体力学软件FLUENT求出不同风攻角下的阻力系数和升力系数,并根据葛劳渥-登哈托原理判断驰振是否发生;根据相关公式计算驰振临界风速.方法二是对FLUENT进行二次开发,将Newmark方法的代码嵌入用户自定义函数UDF,运用FLUENT动网格技术建立二维流固耦合模型进行驰振仿真计算,求出驰振临界风速以及各风速下的振幅变化规律.仿真计算结果表明,横桥向来风时,长方形截面,切角长方形截面A方案的1/10缩尺模型会发生驰振,切角长方形截面B的1/10缩尺模型不会发生驰振,仿真计算结果与风洞试验结果吻合较好,为工程结构气动力截面选型提供依据.

The galloping vibration is an unstable one-degree-of-freedom divergent vibration phenomenon of slender structures under the action of transverse wind direction, which will lead to structural damage and small changes in cross-sectional shape will change the galloping stability of the structures.In this paper, the galloping performance of the 1 / 10 scale model of the suspender of Nanjing Dashengguan Yangtze River Bridge was calculated by two methods for the first time, and the phenomenon of limit cycle vibration in galloping was presented. The design of suspender includes three schemes： rectangular cross section, rectangular cross section A with cut corners, and rectangular cross section B with cut corners. The first method is to calculate the drag coefficient and lift coefficient at different wind angles of attack through the computational fluid dynamics software FLUENT, and the galloping phenomenon is judged according to the principle of Grouw-Denhato, and the galloping critical wind speed is calculated. The second method is to develop FLUENT for the second time and embed the code of Newmark method into user-defined function UDF. The FLUENT dynamic grid technology is used to establish a two-dimensional fluid-solid coupling model for galloping simulation calculation, and the galloping critical wind speed and the amplitude variation law under each wind speed are obtained. The simulation results show that the 1 / 10 scale model of rectangular section and tangent rectangular section A will gallop while the 1 / 10 scale model of tangent rectangular section B will not gallop when the transverse bridge is facing the wind.The simulation results are in good agreement with the wind tunnel test results, providing a basis for aerodynamic section selection of engineering structures.