开口桥梁断面颤振及气动措施的数值与试验研究

针对典型开口桥梁断面颤振抑振措施进行了风洞试验和数值模拟研究.风洞试验结果表明,原型断面在较低风速即发生了颤振失稳现象.通过数值模拟方法进行了颤振模拟,与风洞试验得到了一致的颤振临界风速,并研究了其颤振机理,即高折减风速下断面下表面产生的旋涡脱落及其漂移与断面扭转位移相匹配,产生了与断面运动方向相同的气动扭矩,导致了颤振发散.数值模拟显示,下稳定板可以有效阻碍断面下表面旋涡的脱落和运动,使得气动力在断面运动周期内做功为负,抑制颤振发散.节段模型风洞试验和全桥模型风洞试验结果显示,下稳定板是开口桥梁断面颤振的有效气动抑振措施.

Numerical and Experimental Study of the Mechanism of Torsional Flutter for Open Cross Section Composite Beams

Computational fluid dynamics and experimental methods are utilized to study the flutter characteristic and countermeasure mechanism of open cross section. The wind tunnel test results show that the prototype section of one suspension bridge tends to suffer flutter instability at relatively low wind speeds. The flutter critical wind speed is obtained by using the CFD approach, which conforms well with wind tunnel test results. Numerical simulations show that vortex shedding and drift from the lower surface of the section at high wind speeds match with the torsional displacement of the deck section. Vortex drifting produces the same direction aerodynamic torque as the section movement direction, leading to a flutter divergence. The same calculation is done with three sections added with different types of stabilization plates. The existence of stabilization plate prohibits the development and movement of main vortices, resulting in aerodynamic forces acting on the girder related less to displacement, thus suppress the flutter. Sectional and aerodynamics model wind tunnel tests are conducted to prove the effectiveness of stabilization plates. The results show that the lower stability plate is an effective vibration suppression measure for the flutter of the open cross section.