Collaborative Research: Hybrid Experimental-Numerical Methodology and Field Calibration for Characterization of Peak Wind Effects on Low-Rise Buildings and Their Appurtenances

减轻飓风对建筑物围护结构和附属设施的破坏，特别是对低层建筑物，仍然是实现沿海复原力的主要挑战。建筑围护结构包括屋顶和墙壁覆层系统以及窗、门和车库门等洞口。建筑物附属设施包括安装在屋顶上的可再生能源设备，如光伏阵列、屋顶设备、电信设备，以及尖顶和格子等建筑装饰。在飓风期间，覆层元件和附属设施的损坏可能会刺穿建筑围护结构，使建筑无法使用，原因是水入侵和内部内容丢失。这种损害在很大程度上是由于低估了这些部件上的峰值风荷载。这项研究将综合现场数据、实验和数值分析，以更准确地表征低层建筑的峰值风荷载和风致振动。更好地表征峰值风荷载可以导致更好地设计和改造覆层和附着物，从而减少重大风暴事件期间的建筑脆弱性和社区损失。这项研究将促进可持续的高性能建筑，使用具有抗风能力和可再生的现场能源发电系统，以减少风暴导致的电力中断对社会的破坏。该项目将通过利用STEM项目并利用研究成果向下一代专业人员通报低层建筑屋顶的风暴破坏机理以及如何改进现场可再生能源系统，来加强对代表不足的学生群体的教育。最后，将在测试期间使用网真，以提高对风灾影响的认识，并成为接触更多受众的倍增器。该项目的数据将在国家科学基金会支持的自然灾害工程研究基础设施(NHERI)数据仓库(https://www.DesignSafe-ci.org).)中提供在估计和缓解峰值风对低层建筑及其非结构部件的影响方面，在基本知识方面存在重大差距，这些部件在大风下容易受到破坏。首先，对于低层建筑，需要大型模型来进行准确的测试。然而，这些尺度对湍流模拟施加了限制，导致风洞对强涡度区域的峰值空气动力载荷的估计不保守，在这些区域通常会发生破坏。其次，对于建筑物附属物(例如屋顶太阳能电池板)，目前的风荷载规定中没有考虑高频风致共振振动。研究的目标是创建一种新的基于物理的、混合的实验-数值方法，用于准确预测低层建筑覆层和附属物上的峰值风效应，该方法(A)使用大规模、高雷诺数的物理模型试验来准确模拟高频湍流，(B)用试验后的数值分析来补充试验结果，以纳入缺失的低频湍流和动力响应的影响，以及(C)考虑来自周围结构的干扰影响。这一方法将通过综合建筑部件的现场数据和佛罗里达国际大学国家科学基金会支持的NHERI风墙实验设施的大规模实验结果和相关的数值分析来制定。在现场校准的支持下，这一新方法将允许获得峰值风荷载估计数：(A)不受尺度效应误差的影响，(B)包括迎面流中各种尺度的湍流的影响，包括由周围结构和建筑物本身产生的低频阵风和较小的涡流，以及(C)纳入高频湍流涡流引起的较小附属设备振动的共振放大。这项研究还将有助于制定程序，加强传统边界层风洞在比目前可能的模型尺度更大的情况下模拟湍流的能力，并针对观察到的广泛的飓风对建筑构件造成的破坏，实现新的建筑构件风致动力效应设计准则。此外，这项研究将为制定结构和功能脆弱性曲线奠定基础，包括采用和不采用改造战略，以激励公民采用具有成本效益的改造。NHERI数据仓库提供的关于峰值风影响的现场数据将为研究和专业社区提供信息，并帮助对未来的计算流体力学工具进行基准测试，以改进设计并实现更具弹性的社区。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Mitigating hurricane damage to building envelopes and appurtenances, particularly for low-rise buildings, remains a principal challenge to achieving coastal resilience. Building envelopes include roof and wall cladding systems and openings such as windows, doors, and garage doors. Building appurtenances include roof-mounted renewable energy devices such as photovoltaic arrays, rooftop equipment, telecommunications equipment, and architectural ornamentation such as spires and trellises. During hurricanes, damage to cladding elements and appurtenances can puncture the building envelope and render the building unusable due to water intrusion and loss of interior contents. Such damage largely results from underestimation of peak wind loads on these components. This research will synthesize field data, experiments, and numerical analysis to more accurately characterize peak wind loads and wind-induced vibrations on low-rise buildings. Better characterization of peak wind loads can lead to better design and retrofit of cladding and appurtenances, thus reducing building vulnerabilities and community losses during major windstorm events. This research will foster sustainable, high-performance buildings with wind-resilient and renewable on-site energy generation systems, to reduce societal disruption from windstorm-induced power outages. The project will enhance the education of underrepresented student groups by leveraging STEM programs and using research outcomes to inform the next generation professionals on windstorm damage mechanisms of low-rise building roofs and how to improve on-site renewable energy systems. Finally, telepresence will be used during testing to increase awareness of wind hazard impacts and serve as a multiplier to reach additional audiences. Data from this project will be made available in the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) Data Depot (https://www.DesignSafe-ci.org). Major gaps in fundamental knowledge exist in the estimation and mitigation of peak wind effects on low-rise buildings and their non-structural components, which are vulnerable to damage under high winds. First, for low-rise buildings, large-scale models are needed for accurate testing. However, these scales impose constraints on turbulence simulation, resulting in unconservative wind tunnel estimates of peak aerodynamic loads in areas of strong vorticity where damage is typically initiated. Second, for building appurtenances (e.g., rooftop solar panels), wind-induced resonant vibrations at high frequencies are unaccounted for in current wind load provisions. The research objective is to create a new physics-based, hybrid experimental-numerical methodology for accurately predicting peak wind effects on low-rise building cladding and appurtenances that (a) uses large-scale, high Reynolds number physical model tests that accurately simulate high frequency turbulence, (b) augments the test results with post-test numerical analysis to incorporate the effects of missing low frequency turbulence and dynamic responses, and (c) accounts for interference effects from surrounding structures. This methodology will be developed through a synthesis of in-situ data on building components with results from large-scale experiments at the NSF-supported NHERI Wall of Wind experimental facility at Florida International University and associated numerical analysis. This new methodology, supported by field calibration, will allow obtaining peak wind load estimates that: (a) are not subject to errors due to scaling effects, (b) include the effects of various scales of turbulence in the oncoming flow, including low frequency gusts and smaller eddies generated by the surrounding structures and by the building itself, and (c) incorporate the resonant amplification of vibrations of smaller appurtenances induced by high frequency turbulent eddies. This research will also contribute to formulating procedures that will enhance the ability of conventional boundary layer wind tunnels to simulate turbulence for larger model scales than are currently possible, and achieving new design guidelines for wind-induced dynamic effects on building components, needed in view of observed widespread hurricane-induced damage to such components. In addition, this research will lay the foundation for the formulation of structural and functional fragility curves with and without retrofitting strategies that can incentivize citizens to adopt cost-effective retrofits. Field data on peak wind effects, made available in the NHERI Data Depot, will inform the research and professional communities and help benchmark future computational fluid dynamics tools to enhance design and achieve more resilient communities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.