Natural Hazards Research Summit 2022: Fragility Functions and Experimental Investigation for Hurricane-Induced Wind Loads of Elevated Coastal Houses

Extreme wind events such as hurricanes are the main causes of damage to coastal residential houses in the United States. It is recommended to elevate coastal houses on columns to mitigate hurricane-induced flooding and storm surge hazards. However, post-event forensic studies reported that the envelope components of elevated houses experienced severe wind-induced damage (e.g., underside of the elevated floor, walls, and roofs) which, in many cases, has led to total collapse of the building. Therefore, studying hurricane-induced risks to these houses is important to reduce the losses and to enhance the resilience of coastal communities. Herein, this poster has two objectives: the first is to assess the performance and vulnerability of elevated houses under wind loads, and the second is to accurately determine the wind loads acting on elevated houses considering their unique aerodynamics characteristics and their exposure to stronger winds. For the first objective, empirically-based fragility functions were developed by utilizing damage data from post-hurricane damage assessment reports for both elevated and slab-on-grade houses, respectively. These houses were surveyed after Hurricanes Irma, Harvey, and Michael. For the second objective, this poster presents the major findings of extensive large-scale aerodynamic experiments conducted at the NSF-NHERI Wall of Wind (WOW) Experimental Facility (EF). The developed fragility curves highlighted the higher vulnerability of elevated houses compared to slab-on-grade houses. Furthermore, the aerodynamic test results showed that the underneath floor of elevated houses experiences high suction wind pressures around columns and edges which explain the field damage observations for these regions.