典型箱梁下腹板倾角对桥梁静风稳定性能的影响

Aerodynamic Performance of Bridge with Typical Box Girder Sections at Different Web Inclinations

以大跨桥梁中常用的近流线型箱梁断面为研究对象,通过计算流体动力学(computational fluid dynamics,CFD)方法,选取下腹板倾角这一关键几何参数进行研究,对比分析不同腹板倾角情况下的静风稳定性能,阐述静风失稳机理.研究结果表明,当下腹板倾角较小时,在底板与下游腹板交接处存在负压力区,可以产生向下的升力分量,从而降低升力系数;在一定的下腹板倾角范围内(9°~23°),竖向位移或扭转位移较小,有利于提高静风失稳临界风速.选用下腹板倾角较小(9°~23°)的断面,可有效增大上表面的正压力以及下表面的负压力,降低主梁的升力系数,降低阻力系数,从而达到提高静风稳定失稳风速的目的.

In this paper, concerning the critical aerodynamic geometrical parameters of a box girder, a series of web inclination angles(33 representative angles) were selected to fundamentally investigate the influence of web inclination angles on stationary aerodynamic stability performance of the long span bridge by using the computational fluid dynamics(CFD) method. The results show that there is a negative pressure zone at the junction of the bottom slab and the incline web when the angle of the web is small, which generates the downward force and decreases the lift coefficient of the box girder. By reducing the web inclination angle, the vertical and torsional displacements of the box girder at each wind speed are effectively reduced. The box girder with a lower web inclination angle can reduce the lift coefficient and drag coefficient of the box girder and can improve the stationary aerodynamic stability performance of the bridge.