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Damage Investigation Following Hurricane Irma in Florida
David O. Prevatt, Ph.D.Kurtis R. Gurley, Ph.D.
Chris Ferraro
9 October 2017Tallahassee, FL
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Outline of Presentation
• Hurricane Irma Description & Florida Impact • UF’s Damage Survey Protocol & Participants• Irma’s Peak Winds & FBC Design Wind Speed • Preliminary Damage Observations (Exterior)• Summary and Next Steps
Hurricane Irma’s Impact in Florida
• Landfall in Two landfalls on Florida:– Cudjoe Key, FL à 106 mph gust wind speed at Big Pine Key (9/10/17)– Marco Island à 130 mph (9/10/17: 3:35 pm) at Police Department
• Affected Florida from 10 – 12 Sept. 2017– 116,000 persons in 530 shelters– 11 fatalities (including 8 elderly persons in nursing home AC accident)– Power loss affects ~ 3 million customers– Storm surge and flooding in Miami, the Keys, Everglade City and Naples
UF Damage Assessment Survey • Objective: To Investigate structures in regions experiencing hurricane force
(Cat 3 wind speeds) • Focus à mainly single family houses, some multi-family
– Wind damage– Water intrusion– Storm Surge effects
• Approach:– Ground survey used smartphone app: Fulcrum (www.fulcrum.com)– Aerial survey of specific areas– Conducted in 5 days – 9/12 – 9/17
• Collaborated with National Science Foundation RAPID survey – Led by Notre Dame University– Researchers from FIU (Miami) and FIT (Melbourne), Auburn University– International: James Cook University (Australia), Western University (Canada)
• Coverage: 1,100 structures – 5,000 photographs of exterior building damage– 3D Point Clouds and information on structures
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Data Collection Methodology• Modified Applied Technology Council ATC-20 survey form on smartphone app• All data collected and stored in central server • Photographs and data uploaded once app is synced• GPS location automatically established and address autofilled
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Jacksonville &St Augustine
Miami
Marco Island
Islamorada to Key West
Naples
Fort Myers
Everglades City and Chokoloskee
Preliminary Surveys
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Jacksonville &St Augustine
Miami
Marco Island
Islamorada to Key West
Naples
Fort Myers
Everglades City and Chokoloskee
180
170
160
150
130
140
State of Florida’s Design Wind Speed
Category II (3-sec. gust)
Jacksonville, St. Augustine: • Tornado touchdown – wind speed 130 mph• Coastal erosion along AIA highway• 46 structures surveyed• Most damage moderate
House #1Yr Built: 1982
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Miami:• Estimated wind speed: 83 mph• Generally minor roofing damage • Failed ridge caps on clay tile roofs • 19 structures surveyed
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Naples:• Estimated wind speed: 100 mph• Minor roof damage observed on roof cover• Severe roof damage to mobile homes• Minimal damage to site built structures• 83 structures surveyed
Mobile Homes
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Marco Island:
• Estimated wind speed: 108 mph• Minor roof damage observed on roof cover• Houses have high quality.• 215 structures surveyed
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Everglades City:• Estimated wind speed: 110 mph• severe storm surge • minor wind damage on roof cover• 83 structures surveyed
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Chokoloskee:• Estimated wind speed: 110 mph• severe storm surge • minor roof cover and wall cladding damage• 40 structures surveyed
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Islamorada to Key West:• Estimated wind speed: 116 mph• Wide spread roof cover damage• Also storm surge damage widespread• by FIU and FIT researchers • 513 structures surveyed
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1. WindLoad ∝ WindSpeed /(𝑖𝑠 𝑝𝑟𝑜𝑝𝑜𝑟𝑡𝑖𝑜𝑛𝑎𝑙 𝑡𝑜)
DEFINITION: Windloadratio =ActualWindLoad𝐷𝑒𝑠𝑖𝑔𝑛𝑊𝑖𝑛𝑑𝐿𝑜𝑎𝑑
3. WindLoadRatio = QRSTUVWXYZ[\]]Z^_`abcdacefg__e
/×100%
• Next Slide à Comparing Actual Load vs. Design Load(approximately based on wind speed)
Structural Damage to Wind Speed Relationship
Surveyed RegionExample House
NumberZip Code of
HousesDegree of Damage Year built
Actual Wind Speed(3-sec peak gust )
Design Wind Speed
(Category II)
Wind Load
Ratio (%)
Jacksonville and St Augustine 1 FL 32080 Severe
(Tornado) 1982 130 (EF2 Tornado) 132 97
Miami 2 FL 33135 Minor 1968 83 168 24
Naples3, 4 and 5 FL 34113 Severe
(Mobile Homes) 1984 100 166 36
6 FL 34113 Minor 2001 100 166 36
Marco Island7 FL 34145 Minor 1970 108 169 41
8 FL 34145 Minor 2002 108 169 41
Everglades City
9 FL 34139 Moderate — 110 163 46
10 FL 34139 Severe(surge) — 110 163 46
11 FL 34139 Moderate(surge) — 110 163 46
Chokoloskee 12 FL 34141 Moderate — 110 164 45
Islamorada to Key West
13 FL 33042 Moderate(wind & surge) 1998 116 180 42
14 FL 33043 Moderate(surge) — 116 180 42
Wind Load Ratios & Damage at Survey Sites
Summary & Next Steps• Hurricane Irma was not a design level wind event
• Wind loads ranged from 25% to 97% of design levels• More vulnerable structures in North-Central Florida (lower design wind speeds)
• The question: Should any structures have failed?• Florida structures generally performed okay • The more severe damage more likely in older structures
• However, our preliminary survey à exterior damage only• Storm surge damage & costs high in low-lying areas• Future Work Proposal:
• Conduct interview with home owners to:• Capture & quantify distribution and extent of interior damage• Estimate of repair costs & time and evacuation
• Assess homeowner opinions on retrofit & strengthening home• Capture effects of water intrusion & storm surge
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AcknowledgementWe gratefully acknowledge financial support of the Florida Building Commission
We wish to acknowledge the National Science Foundation RAPID Award through Notre Dame University
Researchers and Student Participation: • Florida International University (Miami, FL)• Florida Institute of Technology (Melbourne, FL)• University of Western Ontario (Canada)• James Cook University (Australia)• Auburn University
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