H形断面桥梁风致振动的流场机理

Flow-map mechanism of wind induced vibrations of H-shape bridge decks

为分析H形断面桥梁风致振动的流场机理,在同济大学TJ-4风洞实验室,采用粒子图像测速系统(PIV)获得以第一塔柯玛桥为原型的H形断面在多种风速下的结构周围流场,并采用激光位移计记录结构在相应风速下的位移响应。通过采用相位平均的方法,并以激光位移计获得的位移信号作为参考信号,获得结构运动四分点相位的流场。通过对设置中央稳定板前后对流场和结构运动状态的分析和比较,发现H形断面的风致振动是由其表面交替运动的旋涡驱动的。在一个完整的周期内,旋涡经历了从生成到脱落的过程,在每个时刻,原始H形断面的上下表面仅存在单个旋涡。

In order to analyze the mechanism of wind induced vibrations of H-shape bridge decks with the 1st Tacoma Narrows Bridge as the prototype, wind tunnel experiments were carried out in a TJ-4 boundary layer wind tunnel. The flow maps around the decks were obtained using Particle Image Velocimetry and the displacements of the decks were also obtained using laser displacements. The flow maps in four typical phase angles were obtained using the phase-averaging technique with the displacement as the reference signal. Based on the characteristics of the flow map around the decks with and without the central stabilizer, it was found that the vibrations of the deck were driven by the vortices on the surface of the decks moving from upstream to downstream. In one complete cycle, the vortices progressed from emergence to separation. At any given time, there is only one vortex in the up and the down sides of the deck.