栏杆高度对流线型箱梁涡振性能影响的试验研究

Experimental Study on Influence of Railings Heights on Vortex-induced Vibration Performance of Streamlined Box Girder

为研究栏杆高度对流线型箱梁涡激振动性能的影响并揭示其机理,通过节段模型风洞动态测压与测振试验,研究了流线型箱梁涡振响应、平均和脉动风压系数、频域特性以及局部升力对涡振的贡献系数分布情况.结果表明:安装栏杆后主梁表面的平均风压系数增大,脉动风压系数变化复杂,脉动风压卓越频率与模型自振频率基本一致,局部升力对涡振的贡献作用增大,使主梁涡振加剧;栏杆高度的变化对主梁表面平均风压系数基本没有影响,但对其脉动风压系数的分布规律及脉动压力功率谱幅值有较大影响;栏杆高度的变化,使主梁上表面前部和尾部区域的局部升力对涡振贡献程度呈现出显著差异,当贡献值增大时,主梁涡振响应增大.当栏杆高度为45%的梁高时流线型箱梁的涡振幅值最大,在此基础上适当降低或增大栏杆高度均有一定的抑振效果,降低栏杆高度效果更好.研究结果为流线型箱梁栏杆的设计和相关研究提供了依据和参考.

To understand the influence of the railing heights on the vortex-induced vibration(VIV)performance of the girder,and to reveal its mechanism,a segment model wind tunnel test including dynamic pressure and vibration measurement was carried out.The VIV response,aerodynamic forces,mean and fluctuating wind pressure coefficients,frequency domain characteristics,and the distribution of contribution coefficient of local lift on VIV were comprehensively analyzed.The results indicate that after installing the railings,the mean wind pressure coefficient is increased,and the fluctuating wind pressure change is complicated.The predominant frequency of fluctuating wind pressure is almost consistent with the natural frequency of the model.And the contribution function of the local lift on VIV increases.Therefore,the VIV phenomenon is far more marked.And the influence of variation in railing height on the surface wind pressure coefficient of the girder is negligible,but it has a great influence on the distribution of fluctuating wind pressure coefficient and the amplitude of fluctuating pressure power spectrum;with different railing heights,local lift in the front and tail areas of the upper surface of the main beam contribute differently to the vortex.When the contribution increases,the VIV response of the main beam increases;when the railing height is 45%of times the beam height,the vortex response of the streamlined box girder is the largest.On this basis,appropriately reducing or increasing the railing height has a certain vibration suppression effect,and especially reducing the railing height shows a better effect.The research results provide a basis and reference for the design and related research of streamlined box girder railings.