Structural Engineers Association of Illinois – April 4, 2006 Building for Extreme Events –...

Structural Engineers Association of Illinois – April 4, 2006Structural Engineers Association of Illinois – April 4, 2006

Building for Extreme Events –Building for Extreme Events –Lessons Learned from KatrinaLessons Learned from Katrina

SEAOI MeetingSEAOI MeetingApril 4, 2006April 4, 2006

William L. Coulbourne, P.E.William L. Coulbourne, P.E.URS CorporationURS Corporation


What is an extreme natural event?What is an extreme natural event?

Flooding – 500-year or .02% annual chance of Flooding – 500-year or .02% annual chance of occurrenceoccurrence

Wind – 150 to 200 mph (Category 5 hurricane Wind – 150 to 200 mph (Category 5 hurricane or tornado)or tornado)

Storm effects create additional problems such Storm effects create additional problems such as debrisas debris

Storm impact such that recovery is Storm impact such that recovery is complicated and takes a long timecomplicated and takes a long time


Building Code Requirements for Building Code Requirements for Katrina Impacted AreasKatrina Impacted AreasAL, MS, LA – no state wide code pre-KatrinaAL, MS, LA – no state wide code pre-Katrina

Some communities enforced either the 1997 Some communities enforced either the 1997 SBC or the IBCSBC or the IBC

IBC references ASCE 7 and ASCE 24IBC references ASCE 7 and ASCE 24

Floodplain maps ranged in age from a few years Floodplain maps ranged in age from a few years to over 20 yearsto over 20 years

Floodplain maps show limits of 100-year or 1% Floodplain maps show limits of 100-year or 1% annual chance of flooding both inland and on the annual chance of flooding both inland and on the coastcoast


Specific Katrina Storm ResultsSpecific Katrina Storm Results

Storm surge elevations were nearly 30 feet in Storm surge elevations were nearly 30 feet in a few areasa few areas

Surge created flooding in back bays far in Surge created flooding in back bays far in excess of flood map elevationsexcess of flood map elevations

Wind speed was less than building code Wind speed was less than building code levels in all but a very small arealevels in all but a very small area

Significant line of surge created debrisSignificant line of surge created debris

Flood protection structures failedFlood protection structures failed


Katrina StatisticsKatrina Statistics

Over 350,000 houses destroyedOver 350,000 houses destroyed

Another 140,000 houses with major damageAnother 140,000 houses with major damage

Total economic losses exceed $125 billionTotal economic losses exceed $125 billion

450,000 displaced people450,000 displaced people

Category 5 storm in the Gulf with 902 millibar Category 5 storm in the Gulf with 902 millibar central pressure – a very strong stormcentral pressure – a very strong storm


Katrina Storm Surge ModelKatrina Storm Surge Model


0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

Sto

rm S

urg

e E

leva

tio

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feet

) Cat 5Cat 3

Cat 1

Gulf Coast Storm Surge – Gulf Coast Storm Surge – SLOSH MODELSLOSH MODEL

LA

Gulfport

FlaAlaMississippi

Biloxi

WEST EAST


So what were the effects from So what were the effects from flooding….flooding….Water washed through first floors if the Water washed through first floors if the building stayedbuilding stayed

Water pushed and floated buildings from their Water pushed and floated buildings from their foundationsfoundations

Surge lifted large, heavy structures like Surge lifted large, heavy structures like parking garagesparking garages

Surge created large mounds of debris and Surge created large mounds of debris and tossed debris (barges) at buildingstossed debris (barges) at buildings


Daulphin Island, AL…successDaulphin Island, AL…success


Waveland, MS …survivorWaveland, MS …survivor


Biloxi, MS…damageBiloxi, MS…damage


Biloxi, MS…severe damageBiloxi, MS…severe damage


Dauphin Island, AL…severe damageDauphin Island, AL…severe damage


Pass Christian, MS…severe damagePass Christian, MS…severe damage


Fire Station (new)…severe damageFire Station (new)…severe damage


Long Beach, MS…total destructionLong Beach, MS…total destruction

The Neighbors: out of +/- 100 homes in the area, we counted 2 survivors


Pass Christian, MS…total destructionPass Christian, MS…total destruction


DebrisDebris


ASCE 7 Wind Speed MapASCE 7 Wind Speed Map

Estimated Actual Wind Speeds

Structural Engineers Association of Illinois – April 4, 2006 Building for Extreme Events –...

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