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 (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.
