RAPID: Assessing the Performance of Elevated Wood Buildings, including Manufactured Housing, in Florida during 2018 Hurricane Michael

这项快速反应研究拨款（Rapid）将调查飓风迈克尔期间现场建造和制造的高架房屋的风力性能，该飓风于2018年10月10日在佛罗里达州登陆，仅比5级飓风低几英里每小时（mph）。这是自1992年安德鲁飓风以来袭击美国大陆的最强飓风。飓风迈克尔的观测影响为研究现场建造和制造的高架房屋的风力性能提供了一个独特而重要的机会，因为在海岸和内陆，记录的风速达到并超过了设计风速。佛罗里达州是美国制造房屋库存最多的州之一，这是最容易受到飓风影响的住宅结构，也往往是社会上最脆弱的家庭。虽然在重大飓风事件之后，制造房屋的损坏已经被广泛注意到，但这种类型的结构却很少受到研究的关注。人造房屋是高架房屋的一个子集，在受飓风迈克尔影响的地区，高架现场建造的房屋也很常见。高程高度、高跷分布和基础类型对现场建造和制造的高架房屋结构的风荷载和损坏的影响目前尚不清楚。该项目将通过收集飓风迈克尔后高架住宅性能的临时数据来调查这些基本知识差距。主要飓风事件造成的灾害损失中，住房的损坏通常占一半，尽管由于家庭流离失所造成了广泛的破坏。本研究的结果将与国家和州一级的规范和标准委员会分享，以提高普通但尚未得到充分研究的住宅建筑的弹性，以促进飓风事件后国家福利和繁荣的连续性。通过该拨款收集的数据将在NHERI数据仓库和侦察门户网站（https://www.DesignSafe-ci.org）上共享，供工程界广泛使用。飓风迈克尔风场的内陆风速范围很广，因此为不同类型的住宅建筑结构（包括现场建造和制造的高架住宅）的现场损害调查提供了机会。目前的规范和标准没有考虑到高架住宅建筑下面的空气流动。初步研究表明，不同的海拔高度可能会放大在墙壁和屋顶表面测量到的风压，这表明目前基于规范的设计方法不保守。RAPID项目将评估一系列高架和非高架房屋的损坏情况，并根据“迈克尔”飓风期间经历设计级别和更高风速的地区的海拔高度、高跷分布和基础类型进行比较。此外，飓风“迈克尔”影响地区的人造房屋的设计适用于II区（100英里/小时）或III区（110英里/小时）的峰值风速，以及75英里/小时的高速公路/州际运输持续风速。目前设计中使用的大多数风荷载考虑三秒阵风风速，这是一种瞬时风荷载，假设在极端风事件中结构部件和材料的行为保持在线性范围内。在风速维持在75英里/小时或更低的地方检查制造外壳的损坏，将有助于了解故障是由疲劳引起的，是由持续的风荷载引起的，还是发展为机组的灾难性故障。这些获得的知识将指导未来制造房屋研究的研究重点，以便为制造房屋的改造（旧）和设计（新）制定更好的损害减轻计划。侦察小组将进入佛罗里达州受飓风迈克尔影响的地区，收集现场数据，包括损坏图像和建筑信息，用于分析和提高高架场地建造和制造住房的基本知识。该奖项反映了美国国家科学基金会的法定使命，并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。

This Grant for Rapid Response Research (RAPID) will investigate the wind performance of elevated site-built and manufactured housing during Hurricane Michael, which made landfall in Florida on October 10, 2018, just a few miles per hour (mph) below a Category 5 hurricane. This hurricane was the strongest to hit the continental United States since Hurricane Andrew in 1992. The observed impact of Hurricane Michael presents a unique and important opportunity to investigate the wind performance of elevated site-built and manufactured housing, given that recorded wind speeds reached and exceeded design winds at the coast and further inland. Florida has one of the largest inventories in the United States of manufactured housing, the most vulnerable residential structure to hurricanes, which also often houses the most socially vulnerable households. While damage to manufactured housing has been widely noticed following major hurricane events, this type of structure has received minimal research attention. Manufactured housing is a subset of elevated housing, where elevated site-built homes are also very common in the areas impacted by Hurricane Michael. The influence that the elevation height, stilt distribution, and foundation type have on wind loading and damage experienced by elevated site-built and manufactured housing structures is presently unknown. This project will investigate these fundamental knowledge gaps through ephemeral data collection of the performance of elevated housing following Hurricane Michael. Damage to housing is often responsible for half of the disaster losses following major hurricane events notwithstanding the widespread disruption it causes through household dislocation. Findings from this study will be shared with national and state-level codes and standards committees to improve the resilience of common, but understudied, residential buildings, in order to promote continuity in national welfare and prosperity following a hurricane event. Data collected through this grant will be shared on the NHERI Data Depot and Reconnaissance Portal (https://www.DesignSafe-ci.org) for broad use by the engineering community.The Hurricane Michael wind field had a wide range of inland wind speeds, and thus presents the opportunity for on-site damage investigation of different types of residential building structures, including elevated site-built and manufactured homes. Current codes and standards do not account for the air flow that occurs underneath elevated residential buildings. Preliminary research has shown that different elevations could amplify the wind pressures measured on the wall and roof surfaces, suggesting unconservatism in current code-based design approaches. This RAPID award will assess damage to a range of elevated and non-elevated homes, and make comparisons based on elevation height, stilt distribution, and foundation type in areas that experienced design-level and higher wind speeds during Hurricane Michael. Furthermore, manufactured homes in the Hurricane Michael impacted areas are designed for either Zone II (100 mph) or Zone III (110 mph) peak wind speeds, as well as for 75 mph sustained wind for transportation on highway/interstate purposes. Most wind loads used in design currently consider three-second gust wind speed, which is an instant wind load that assumes structural component and material behaviors stay in the linear range during an extreme wind event. Examining damage to manufactured housing at the sites where wind speeds were sustained at 75 mph or less will advance missing knowledge on whether failures are initiated by fatigue, caused by sustained wind loads, and progress into catastrophic failure of the unit. This gained knowledge will direct future research foci for manufactured housing studies to have better damage mitigation plans for both retrofit (old) and design (new) of manufactured homes. The reconnaissance team will enter areas in Florida affected by Hurricane Michael and collect on-site data, including images of damage and building information, for analyses and advancement of fundamental knowledge on elevated site-built and manufacturing housing.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.