Structural Engineers Association of Illinois – April 4, 2006 Building for Extreme Events – Lessons Learned from Katrina SEAOI Meeting April 4, 2006 William L. Coulbourne, P.E. URS Corporation

Structural Engineers Association of Illinois – April 4, 2006 What is an extreme natural event?  Flooding – 500-year or.02% annual chance of occurrence  Wind – 150 to 200 mph (Category 5 hurricane or tornado)  Storm effects create additional problems such as debris  Storm impact such that recovery is complicated and takes a long time

Structural Engineers Association of Illinois – April 4, 2006 Building Code Requirements for Katrina Impacted Areas  AL, MS, LA – no state wide code pre-Katrina  Some communities enforced either the 1997 SBC or the IBC  IBC references ASCE 7 and ASCE 24  Floodplain maps ranged in age from a few years to over 20 years  Floodplain maps show limits of 100-year or 1% annual chance of flooding both inland and on the coast

Structural Engineers Association of Illinois – April 4, 2006 Specific Katrina Storm Results  Storm surge elevations were nearly 30 feet in a few areas  Surge created flooding in back bays far in excess of flood map elevations  Wind speed was less than building code levels in all but a very small area  Significant line of surge created debris  Flood protection structures failed

Structural Engineers Association of Illinois – April 4, 2006 Katrina Statistics  Over 350,000 houses destroyed  Another 140,000 houses with major damage  Total economic losses exceed $125 billion  450,000 displaced people  Category 5 storm in the Gulf with 902 millibar central pressure – a very strong storm

Structural Engineers Association of Illinois – April 4, 2006 Katrina Storm Surge Model

Structural Engineers Association of Illinois – April 4, 2006 Gulf Coast Storm Surge – SLOSH MODEL LA Gulfport FlaAlaMississippi Biloxi WESTEAST

Structural Engineers Association of Illinois – April 4, 2006 So what were the effects from flooding….  Water washed through first floors if the building stayed  Water pushed and floated buildings from their foundations  Surge lifted large, heavy structures like parking garages  Surge created large mounds of debris and tossed debris (barges) at buildings

Structural Engineers Association of Illinois – April 4, 2006 Daulphin Island, AL…success

Structural Engineers Association of Illinois – April 4, 2006 Waveland, MS …survivor

Structural Engineers Association of Illinois – April 4, 2006 Biloxi, MS…damage

Structural Engineers Association of Illinois – April 4, 2006 Biloxi, MS…severe damage

Structural Engineers Association of Illinois – April 4, 2006 Dauphin Island, AL…severe damage

Structural Engineers Association of Illinois – April 4, 2006 Pass Christian, MS…severe damage

Structural Engineers Association of Illinois – April 4, 2006 Fire Station (new)…severe damage

Structural Engineers Association of Illinois – April 4, 2006 Long Beach, MS…total destruction The Neighbors: out of +/- 100 homes in the area, we counted 2 survivors

Structural Engineers Association of Illinois – April 4, 2006 Pass Christian, MS…total destruction

Structural Engineers Association of Illinois – April 4, 2006 Debris

Debris

ASCE 7 Wind Speed Map Estimated Actual Wind Speeds