极端波浪作用下T梁与箱梁受力研究

Study of Extreme Wave Forces on T-and Box-Types Girder

近海桥梁常采用的箱形截面主梁与T形截面主梁由于几何构型差异较大,在极端波浪(海啸和飓风)作用下波浪力有较大差别.分别以孤立波、椭圆余弦波模拟海啸和飓风波浪,基于RANS方程和SST k-ω湍流模型建立二维数值模型,采用VOF(volume of fluid)法追踪自由液面,对数值水槽造波效果及波浪力计算结果进行验证;在此基础上,分析海啸和飓风作用下波高及淹没系数对T梁、箱梁受力的影响,并比较二者受力差别.研究结果表明:海啸波作用下,箱梁受到的水平力峰值小于T梁,最大差值接近箱梁水平力峰值的32%,箱梁的竖向力峰值大于T梁,最大差值接近T梁竖向力峰值的13%;飓风波作用下,箱梁的水平力峰值小于T梁,最大差值接近箱梁水平力峰值的31%,且箱梁的竖向力峰值小于T梁竖向力峰值;相比于飓风波,海啸对桥梁主梁的作用力更大,对桥梁安全性威胁更大.

The extreme wave forces on costal bridges with T-type girder and box-type girder have great differences due to their special geometrical shapes.First,numerical models based on solitary wave theory and cnoidal wave theory were developed to simulate the tsunami waves and hurricane waves,in which the RANS(Reynolds-averaged Navier-Stokes)equations combined with the SST(shear stress transport)k-ωturbulence model were utilized to describe the mean flow motion,and the VOF(volume of fluid)method was used to trace the interface of air and water.Then,the effectiveness of the numerical models was verified.On this basis,the tsunami and hurricane induced wave forces on T-type girder and box-type girder were compared and discussed,considering different wave heights and submergence depths.The results show as follows:Tsunami wave induced horizontal peak forces on T-type girder are greater than those on box-type girder by over 32%;however,the boxtype girder suffers greater vertical peak forces than the T-type girder and the maximum difference between them is near 31%.Hurricane induced horizontal peak forces on T-type girder are greater than those on box-type girder by over 31%;meanwhile,the vertical peak forces on T-type girder are also greater than those on box-type girder.Compared with hurricane waves,tsunami waves pose a greater threat to the safety of coastal bridges.