大跨度桥梁主梁风雨致涡激振动试验研究

Experimental study on wind-rain-induced and vortex-induced vibration in bridge deck sections of long-span bridges

针对风雨联合作用下的大跨桥梁风雨致涡激振动问题,以某一分离式双箱主梁桥梁及其闭口主梁型式桥梁为研究对象,通过在大气边界层风洞中搭建风雨联合作用试验系统,完成风雨联合作用下大跨桥梁节段模型涡激振动试验.试验结果显示:不同雨强下,开口节段模型涡激振动的起振风速及锁定风速基本一致,但最大振动幅值有一定差别.不同雨强下,闭口节段模型随机振动的振动时程有一定差别,且随着风速增大,振动幅值增大.开口节段模型风雨联合作用下的位移幅值大于单一风作用下的位移幅值,最大增量可达1/4.得出结论:降雨增大了桥梁主梁涡激振动幅值;闭口节段模型相对开口节段模型在抵抗涡激振动方面性能更优良.

The vortex-induced vibration test in bridge deck sections of long-span bridges was carried out by considering vortex-induced vibration characteristics under the simultaneous actions of wind and rain,taking a separated twin-box girder bridge and its closed form as research objects.A system of simultaneous actions of wind and rain built in an atmospheric boundary layer wind tunnel was also utilized.Experimental results display that the wind speed at the start of oscillation and the wind speed of the lock-in region for the slotted section model show no difference in various rainfall intensities,but the maximal amplitudes of vortex-excited resonance display some differences.The time histories of stochastic vibration for the closed section model have some differences in various rainfall intensities,and the amplitude of vibration increases with rising wind speed.The displacement amplitude under the simultaneous actions of wind and rain is larger than the displacement amplitude under a single wind load;the highest increment reaches one quarter.Experimental results also show that the amplitude of vortex-induced vibration in bridge deck sections is increased by rainfall.The closed model has better performance in resisting vortex-induced vibration than the slotted model.