基于代理模型的大跨屋盖气动抗风措施优化研究

Appropriate aerodynamic wind-resistant measures in the wind-load sensitive area of large-span roofs can be applied to mitigate vortices and consequently reduce the wind loads. The main target of aerodynamic measure optimizations is to search the optimal design scheme, in order to further promote the wind-resistant performance of large-span roofs. Up to date, surrogate model method has been the most prevalent approach in the optimization studies of engineering structures, and has recently been used in the aerodynamic measure design of high-rise buildings. However, only limited attention has been paid on the aerodynamic measure optimizations for the large-span roofs. Therefore, in the current project, an improved surrogate-based optimization algorithm will be proposed, based on the evaluation and improvement of existing infill sampling criteria for the surrogate model；Combined with the use of CFD numerical simulations, the surrogate models for the optimizations of porous deflector plates and local modifications of architectural configuration of the flat and cantilevered roofs will be established, to minimize the local wind suction in the wind-load sensitive area and the lift coefficient. The aim of the optimizations is to obtain the optimal design scheme of aerodynamic measures associated with the best wind-resistant performance of large-span roofs. Finally, The optimal results of the aerodynamic measures will be evaluated based on the analysis of global wind pressure distributions, the width of vortices, peak suctions at axis of vortices and etc., and will also be verified by the wind tunnel tests. Based on the above work, it is aimed to extend the wind-resistant design ideas for the large-span roofs, and to promote the development and application of aerodynamic wind-resistant measures.

在大跨屋盖风敏感区域采取适当的气动抗风措施，能够在源头上抑制旋涡作用以降低风荷载，而对气动抗风措施优化的目的是寻找其最优的设计方案，进一步提升屋盖结构的抗风性能。目前，基于代理模型的优化方法已成为工程优化设计领域的热点技术，在高层建筑气动抗风措施设计中得到一定应用，但国内外针对大跨屋盖气动抗风措施的优化研究甚少。为此，本项目将在评价与改进现有代理模型加点准则的基础上，提出基于代理模型的改进优化算法；结合数值模拟技术，针对平屋盖和悬挑屋盖，以风敏感区域内局部风吸力及整体升力系数最小为优化目标，建立设置透风导流板和建筑外形局部修正两种气动抗风措施优化的代理模型，以获得最优的设计方案，使屋盖结构的抗风性能达到最优，最后从整体风压分布、旋涡作用范围及涡核处峰值吸力等方面综合评判优化结果，并结合风洞试验数据加以验证。通过以上工作，旨在拓展现有大跨屋盖结构的抗风设计思路，促进气动抗风措施的应用与发展。

历年来大跨屋盖在台风或飓风等极端风况下的风致破坏事件频发，其原因多归结于屋面风敏感区易遭受锥形涡或分离涡等破坏性旋涡作用。为在源头上抑制旋涡作用并减小风荷载，本项目针对大跨屋盖的气动抗风措施及其优化设计开展了系统性研究。结合Kriging模型、拉丁超立方采样技术和遗传算法等，提出了基于代理模型的气动抗风措施优化设计方法，并通过Benchmark数学测试算例，验证了该算法的计算效率、预测精度及鲁棒性；采用附加源项法来模拟多孔连续介质对气流的阻塞作用，对动量方程、湍动能方程和耗散率方程分别进行修正，提出了多孔气动抗风措施的数值模拟方法，并应用到火电厂防风栅和轻型平屋盖女儿墙防风效果的数值模拟研究中，通过风洞试验对该方法进行了验证；针对平屋盖、球面屋盖和柱面屋盖三种典型大跨屋盖结构开展了风洞测压试验，以风敏感区域内局部风吸力及屋盖整体升力系数最小为优化目标，分别构建了设置透风女儿墙和建筑外形修正两种气动抗风措施优化的代理模型，确定了最优的设计方案，并揭示了气动抗风措施对旋涡作用的抑制效果。本项目的完成对于提升大跨屋盖的抗风性能、减轻极端风况灾害、以及推动气动抗风措施的应用与发展具有较重要的工程实际意义。