流线型箱梁气动外形的数值优化

为改善基于风洞试验的桥梁断面气动外形优化方法所固有的人力物力耗费、搜索范围有限等缺点,提出了一套基于数值计算和数学策略的主梁气动外形优化方法。选取断面下腹板倾角和梁高作为设计变量,以计算流体力学(CFD)模拟和颤振时域法作为数值计算手段替代风洞试验,将试验设计、蚁群混合遗传算法与Kriging代理模型作为协同数学策略替代试错法,探索优化了苏通长江大桥流线型箱梁断面颤振性能最佳的参数匹配方案。结果显示,设计域内最优断面颤振临界风速比原型断面提高8%,下腹板倾角相比梁高对颤振性能影响更大,且存在交互作用。主梁断面气动外形数值优化方法能够较好地取代风洞试验进行外形寻优,研究对以后大跨度桥梁断面选型具有借鉴意义。

Numerical aerodynamic shape optimization of streamlined box girder

To alleviate the problems of the aerodynamic shape optimization (ASO) method of bridge section based on wind tunnel test, such as manpower and material cost as well as limited search range, the ASO method of main girder based on numerical calculation and mathematical strategy was proposed. Taking the streamlined box girder of Sutong Changjiang Bridge as an example, the lower web inclination angle and beam height were selected as design variables, the computational fluid dynamics (CFD) simulation and flutter time domain method were adopted as numerical calculation methods to replace the wind tunnel test, the experimental design, hybrid ant colony genetic algorithm, and Kriging model were used as the collaborative mathematics strategy to replace the trial-and-error method, and the optimal parameter matching scheme of the flutter performance of the beam section was explored. The optimization results show that the critical flutter wind speed of the optimal section in the design domain was 8% higher than that of the original section. The lower web inclination angle had a greater influence on the flutter performance than the beam height, and there was interaction between the two variables. The numerical ASO method of main beam section could better replace the wind tunnel test for shape optimization, and the research could be used as reference for the selection of long-span bridge sections.