筒形拱桥数值风洞模拟及体型系数研究

Numerical wind tunnel simulation and shape factor of cylindrical arch bridge

基于桥梁风工程及流体力学理论,探讨了网格尺寸、湍流模型和壁面粗糙度等对筒形拱桥表面风压特性的影响.通过对壁面粗糙度的模拟分析可知:随着壁面粗糙度的增大,背风面的涡旋增多,建筑背风面所受风吸力增大.将数值模拟结果与试验结果进行比较,验证了数值模拟的精确性和可行性.在此基础上采用最优模拟方法(SST k-ω,壁面粗糙度0.1),研究了椭圆形、圆形和矩形截面的拱形桥梁的抗风性能以及拱顶外凸平台对结构表面风荷载特性的影响,并给出各形状拱桥的局部体型系数,弥补了规范中关于此类拱形结构体型系数的空白.抗风性能最好的体型为椭圆形,其次是圆形,矩形相对较差.拱顶观光平台的存在可以有效减小拱上下侧面的风吸力,尤其对平台附近作用明显.

Based on bridge wind engineering and fluid mechanics theory,the effects of grid size,turbulence model,and wall roughness on wind pressure characteristics of cylindrical arch bridge were discussed.Through the simulation analysis of wall roughness,it can be known that as the wall roughness increases,the vortex on the leeward surface increases,and the wind suction force on the leeward surface of the building increases.The numerical simulation results are compared with experimental results,which verifies the accuracy and feasibility of the numerical simulation.On this basis,the optimal simulation method(SST k-ω,wall roughness 0.1)is used to study the wind resistance of arch bridges with oval,circular and rectangular cross sections,as well as the effect of convex platform at arch top on the surface wind load characteristics.The local shape coefficients of various types of bridges are given,which makes up for the blank of shape coefficients of such arched structures in the code.The best shape for wind resistance is oval,followed by round,and rectangular is relatively poor in case of wind resistance.A platform at arch top can effectively reduce the wind suction on the upper and lower sides of the arch,especially in the vicinity of the platform.