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的破坏，仍然是实现沿海抗灾能力的主要挑战。 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。建筑附属物包括屋顶安装的可再生能源设备，如光伏阵列、屋顶设备、电信设备和建筑装饰，如尖顶和格子。 在飓风期间，对包层元件和附属设施的损坏会刺穿建筑物的外壳，并由于水的侵入和内部内容物的损失而使建筑物无法使用。这种损坏主要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，以更准确地描述低层建筑的峰值风荷载和风振特性。更好地表征峰值风荷载可以导致更好的设计和改造的包层和附属设施，从而减少建筑物的脆弱性和社区的损失，在重大风暴事件。这项研究将促进可持续的，高性能的建筑物与风力弹性和可再生的现场能源发电系统，以减少社会破坏的风暴引起的停电。该项目将通过利用STEM项目和利用研究成果来向下一代专业人员提供有关低层建筑屋顶的风暴破坏机制以及如何改善现场可再生能源系统的信息，从而加强对代表性不足的学生群体的教育。最后，远程呈现将在测试期间使用，以提高对风灾害影响的认识，并作为一个倍增器，以达到更多的观众。 该项目的数据将在NSF支持的自然灾害工程研究基础设施（NHERI）数据库（https：//www.example.com）中提供。www.DesignSafe-ci.org在估计和减轻高峰风对低层建筑物及其非结构性构件的影响方面，基础知识存在重大差距，这些建筑物在大风下容易受到破坏。首先，对于低层建筑，需要大比例模型进行精确测试。然而，这些尺度对湍流模拟施加了限制，导致在强涡度区域（通常是损伤开始的地方）对峰值气动载荷的风洞估计不保守。 其次，对于建筑附属物（例如，屋顶太阳能电池板），在当前的风荷载规定中没有考虑到在高频率下的风引起的共振。本研究的目的是建立一种新的基于物理的混合实验-数值方法，用于准确预测低层建筑覆层和附属物的峰值风效应，该方法（a）使用大尺度、高雷诺数物理模型试验，准确模拟高频湍流，（B）通过试验后数值分析来增强试验结果，以纳入缺失的低频湍流和动态响应的影响，以及（c）考虑来自周围结构的干扰效应。该方法将通过综合建筑构件的现场数据和佛罗里达国际大学NSF支持的NHERI风墙实验设施的大规模实验结果以及相关的数值分析来开发。这种新的方法，在现场校准的支持下，将允许获得峰值风荷载估计：（a）不受比例效应引起的误差的影响，（B）包括迎面气流中各种湍流比例的影响，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）结合由高频湍流涡流引起的较小附属物的振动的共振放大。 这项研究还将有助于制定程序，提高传统边界层风洞模拟比目前可能的更大模型比例的湍流的能力，并实现新的设计准则，考虑到观察到的广泛飓风引起的对建筑物构件的破坏，风引起的动态影响。此外，这项研究将奠定基础，制定结构和功能的脆弱性曲线，有和没有改造策略，可以激励公民采取具有成本效益的改造。在NHERI数据仓库中提供的关于峰值风效应的现场数据将为研究和专业团体提供信息，并帮助基准未来的计算流体动力学工具，以增强设计和实现更有弹性的社区。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

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.