基于浮框式测力模型的桥梁涡激力特性研究

Study on Characteristics of Vortex-induced Forces on a Bridge Deck Based on a Dynamometric Model with Suspension Frame

基于开发的内置浮框式三节段测力模型装置,通过弹性悬挂测振风洞试验测试了某大跨度斜拉桥初步设计主梁断面的涡振响应及对应的涡激力.分析了发生竖向涡激共振的0°与+3°两种风攻角下的数据,验证了内置浮框式三节段测力模型在桥梁断面气动力测试中的可靠性,对比研究了不同风攻角下涡激力与涡激振动响应的测试结果,探讨了锁定区间范围内涡振频率、力与位移之间相位差及涡激力做功的变化情况.结果表明,内置浮框式三节段测力模型可以在风致振动过程中同步测试气动力;所测试得到的涡激力频率在风速锁定区间内与位移响应频率完全一致,同时,模型的竖弯涡激力与涡激振动位移响应之间存在的相位差随风速增大而增大,而涡激力做功有一个先增大后减小的变化过程.

Based on the developed three segment model with inner dynamometric suspension frame,the vortex induced vibration （VIV） and the corresponding vortex induced forces （VIF） of preliminary design deck of a long span cable stayed bridge were measured through wind tunnel test with aeroelastic section model. Through the analysis of VIV under 0° and ＋3° wind attack angle,the dynamometric model was proved to be effective for measuring aerodynamic forces on bridge deck. In addition,the recorded displacements and forces of VIV under different wind attack angles were compared,and the varying curves of VIV frequency,phase difference between force and displacement as well as the work applied by VIF in lock in range were also discussed. The results show that the dynamometric model can measure the aerodynamic forces simultaneously when the model is vibrated. Furthermore,for the lock in range,the VIF frequencies were the same as displacement frequencies,and the phase difference between VIF and displacement increased with the wind speed growth,while the work applied by VIF demonstrated the trend of increasing firstly and then decreasing.