中日欧桥梁抗风设计规范涡激振动对比研究

Comparative Study on Vortex-Induced Vibration Stipulations in Wind-Resistant Design Specifications for Bridges in China,Japan and Europe

为深入了解不同规范中桥梁涡激振动的相关规定以指导桥梁抗风设计,对中国、日本和欧洲桥梁抗风设计规范中的涡激振动相关条文进行对比研究。首先对比了3种规范的结构阻尼、起振风速、涡激振动振幅和允许振幅的取值或计算方法,在此基础上,以日本东京湾海峡大桥为背景,按照3种规范计算了该桥涡激振动起振风速、振幅及允许振幅,并与实测结果进行对比。结果表明:3种规范的桥梁结构阻尼比取值接近,中国规范的钢-混组合结构或混凝土结构阻尼比取值大于其它规范;中国、日本规范和欧洲规范分别采用结构振动位移和运动加速度为指标计算主梁涡激振动允许振幅,当主梁基频较低时,采用欧洲规范可能会低估涡激振动对桥梁的影响;3种规范均可较为准确地预测主梁涡激振动的起振风速,但可能会低估涡激振动振幅。3种规范仅适用于200 m或300 m跨度以下的桥梁,对于大跨度桥梁需结合位移和加速度等多项指标评价涡激振动的影响。

The stipulations of vortex-induced vibration(VIV)in the wind-resistant design specifications for bridges in China,Japan and Europe are compared and analyzed.Firstly,the structural damping,critical wind speed,VIV amplitude and the allowable amplitude or calculation methods suggested in different specifications are selected for comparison.Then,the critical wind speed of VIV,vibration amplitude and allowable amplitude of the Trans-Tokyo Bay Crossing Bridge in Japan are computed,referencing different specifications,and the calculations are compared with the measured data.It is shown that the structural damping ratios for the steel-concrete composite and concrete structures suggested in the Chinese and Japanese specifications as well as Eurocodes approximate each other,and the recommended structural damping ratios in the Chinese specifications are larger.To calculate the allowable amplitude of VIV of bridge deck,different specifications suggest different indexes,specifically,the structural vibration displacement in Chinese and Japanese specifications and motion accelerations in Eurocodes.When the fundamental frequency of the bridge deck is relatively low,the effect of VIV on bridge is likely to be underestimated with Eurocodes.The critical wind speed of VIV of bridge deck can be accurately predicted with Chinese and Japanese specifications as well as Eurocdes,but the VIV amplitude would be undervalued.The wind-resistant design specifications for bridges in China,Japan and Europe suit bridges with span lengths between 200 m and 300 m.For bridges of longer spans,multiple indexes,including displacement and acceleration,should be considered to evaluate the VIV effect.