RAPID/Collaborative Research: Performance of Low-Rise Large-Volume Buildings in Florida during 2018 Hurricane Michael

低层大容积（LRLV）金属建筑是社区和国家复原力的关键组成部分，通常用作学校礼堂或体育馆，军用或民用飞机机库，配送中心，超市，教堂，工业和制造业建筑以及保护高价值财产的存储设施。不幸的是，飓风迈克尔于2018年10月10日在佛罗里达的巴拿马城以南登陆，其中许多建筑物遭受灾难性倒塌或不可挽回的破坏，成为4级飓风。NSF支持的结构极端事件侦察网络的初步评估发现，这些结构的损坏是常见的，并且通常与周围的建筑物不成比例，这表明在理解这些结构的动态载荷和/或极端风事件期间结构对这些载荷的响应机制方面存在知识差距。快速反应研究（RAPID）将支持现场部署，以高分辨率3D点云的形式，通过地面和机载激光雷达和摄影测量，以及法医结构工程分析，快速准确地捕捉飓风后LRLV建筑物的损坏状态。数据的后处理和分析将为这些建筑的风荷载和结构响应提供先进的计算模型，最终实现更安全、更高效的设计。通过更好地了解这些建筑物在风荷载下的复杂动态行为，该项目的研究结果可以为未来的设计提供信息，以减少未来极端风事件中LRLV建筑物故障的频率。现场勘察和分析将培训本科生和研究生工程师的法医工程方法，并提供高质量的案例研究，可供工程教育界使用。 从该奖项收集的数据将存档在NSF支持的自然灾害工程研究基础设施（NHERI）数据库（https：www.DesignSafe-CI.org）。 在飓风期间，LRLV金属建筑物的尺寸可能超过湍流的整体长度尺度，在建筑物表面上产生不连贯的阵风结构。这种现象对峰值结构力的影响，特别是内部压力响应，还没有很好的理解。该项目的目标是：1）在清理之前，保持受飓风迈克尔影响的LRLV建筑物在飓风后的精确状况，2）评估LRLV建筑物所经受的极端风况，3）对LRLV建筑物故障的主要驱动因素进行初步评估，以及4）定位未来的研究工作，进行先进的风荷载和结构分析模拟，以解决导致大故障率的关键知识差距。在佛罗里达的数据收集考察（3-5天）将使用多种传感技术快速收集目标结构的详细结构信息，包括地面激光雷达和测量，以及基于无人机的激光雷达和图像。在将数据简化为3D模型后，分析过程将侧重于参数，包括建筑物体积，无保护开口尺寸，建筑物相对于主风向的方向，内部压力的共振，结构系统（重力和横向），结构年龄和事件发生前的条件。这项研究将解决一个关键的知识差距，飓风引起的风荷载对LRLV建筑物，同时调查这些负载的结构系统响应。该奖项反映了NSF的法定使命，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，被认为值得支持。

Low-rise, large-volume (LRLV) metal buildings are a critical component to community and national resilience, often functioning as school auditoriums or gymnasiums, military or civilian aircraft hangars, distribution centers, supermarkets, churches, industrial and manufacturing buildings, and storage facilities protecting high-value property. Unfortunately, many of these structures suffered catastrophic collapses or irreparable damage following Hurricane Michael, which made landfall south of Panama City, Florida on October 10, 2018, as a Category 4 hurricane. Preliminary assessments by the NSF-supported Structural Extreme Events Reconnaissance network found that damage to these structures was common and often disproportionate to surrounding buildings, indicating a knowledge gap in the understanding of the dynamic loads on these structures and/or the mechanisms of structural response to these loads during extreme wind events. This Grant for Rapid Response Research (RAPID) will support field deployments to quickly and precisely capture the post-hurricane damage state of LRLV buildings in the form of high-resolution 3D point clouds, by means of terrestrial and airborne LIDAR and photogrammetry, and forensic structural engineering analysis. Post-processing and analysis of the data will inform advanced computational models of wind load and structural response for these buildings, which will ultimately enable safer and more efficient designs. By enabling a better understanding of the complex dynamic behavior of these buildings under wind loads, the findings from this project can inform future designs to reduce the frequency of LRLV building failures in future extreme wind events. The field reconnaissance and analysis will train undergraduate and graduate engineers in forensic engineering methods and provide high quality case studies that can be used by the engineering education community. Data collected from this award will be archived in the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) Data Depot (https://www.DesignSafe-CI.org). During hurricane-force winds, the dimensions of LRLV metal buildings can exceed the integral length scales of the turbulent flow, producing incoherent gust structures over the surface of the building. The effects of this phenomenon on peak structural forces, and particularly the internal pressure response, are not well understood. The goals of this project are to: 1) preserve the precise post-hurricane condition of LRLV buildings impacted by Hurricane Michael prior to cleanup, 2) assess the extreme wind conditions to which the LRLV buildings were subjected, 3) conduct preliminary assessments of the primary drivers of LRLV building failures, and 4) position future research efforts for conducting advanced wind load and structural analysis simulations to address the key knowledge gaps that have led to large failure rates. Data gathering excursions (3-5 days) in Florida will use multiple sensing technologies to quickly gather detailed structural information on target structures including terrestrial LIDAR and measurements, and drone-based LIDAR and imagery. After reducing the data into 3D models, the analysis process will focus on parameters including building volume, unprotected opening size, building orientation with respect to primary wind direction, resonance of internal pressure, structural system (gravity and lateral), structure age, and pre-event condition. This study will address a key knowledge gap in hurricane-induced wind loads on LRLV buildings while simultaneously investigating the structural system response to these loads. The holistic approach will advance scientific understanding of the phenomena driving the failures of these systems and inform more resilient building designs for future events.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.