design of tsunami safe haven structures - apwa...
TRANSCRIPT
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Design of Tsunami Safe Haven Structures
Cale Ash, PE, SE – Degenkolb
Dan Trisler, PE, GE – Hart Crowser, Inc.
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Outline
• Tsunami and Other Seismic Hazards
• Safe Haven Structures
• Ocosta Case Study– Geotechnical Considerations
– Structural Considerations
Cale Ash, PE, SE Dan Trisler, PE, [email protected] [email protected]
600 University StreetSeattle, WA 98101
206.262.9240
www.degenkolb.com
300 West 15th StreetVancouver, WA 98660
360.448.4189
www.hartcrowser.com
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Tsunami / Seismic Hazard
• Earthquake Sources• Tsunami• Strong Ground Shaking• Fault Rupture• Liquefaction• Lateral Spread
Northwest Earthquake Sources
Source: USGS
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Washington Faults
Tsunami Generation
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Tsunami Generation
Tsunami
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Source: Presentation by Dr. Reiji Tanaka, Tohoku Institute of Technologyand Junji Ogawa, Akita Prefectural University
Tsunami (before)
Source: Presentation by Dr. Reiji Tanaka, Tohoku Institute of Technologyand Junji Ogawa, Akita Prefectural University
Tsunami (after)
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Strong Ground Shaking
Source: USGS
Design EQ Estimated PGA: 2% probability in 50 years
Washington
Fault Rupture/Subsidence-Uplift
2016 Kaikoura, New Zealand (Mw = 7.8)
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Liquefaction
February 28, 2001 Nisqually, WA: Boeing Field
Liquefaction
1964 Niigata, Japan
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Lateral Spreading
2016 Kaikoura, New Zealand (Mw = 7.8)
Lateral Spreading
2016 Kaikoura, New Zealand (Mw = 7.8)
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Tsunami Safe Havens
• What Are They?
• When/Where Needed?
• Design Considerations
• Preference given to high ground
• Manmade high ground in form of mound
• Building or other structure designed for tsunami loads
Vertical Evacuation Options
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• Earth mounds can act as effective evacuation sites
• Must be high and large enough
Manmade High Ground
• Port Authority Bldg.
• Kesennuma, Japan
• Designated as tsunami refuge
• Flooded to third level
• Numerous survivors sought refuge on roof
Vertical Evacuation Building / Refuge
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Tsunami Inundation Mapping
Westport Area(ASCE-7-16) Ocosta
Elementary
Tsunami Inundation Mapping
Westport Area(WADNR, 2000)
Ocosta Elementary
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Tsunami Inundation Mapping
Puget Sound(ASCE-7-16)
• 2008 – FEMA P646
• 2012 IBC Appendix M– Not adopted in WA
• 2016 ASCE 7 Chapter 6
• 2018 IBC – 2019 Adoption in WA
Building Code Status
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• Hydrostatic Forces• Buoyant Forces• Hydrodynamic Forces• Impulsive Forces• Debris Impact Forces• Damming of Waterborne Debris• Uplift on Elevated Floors• Additional Gravity Loads on Elevated
Floors
ASCE 7-16 Chapter 6
Lessons from Tohoku
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Foundations – Toppling
Foundations – Scour
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Debris Impact
Wood Construction1.5 m to 2 m: 34% destroyed2 m to 2.5 m: 72% destroyed4 m and over: 100% destroyed
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Steel Construction
Concrete Construction
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Ocosta Elementary School
The nation’s first tsunami safe haven!
• Paula Akerlund/Ocosta & Doug Nichols/CSG• Brian Ho & Brian Fitzgerald/TCF Architecture • Cale Ash/Degenkolb• Dan Trisler/Hart Crowser• Ken Goettel/Goettel & Associates• Frank Gonzalez, et al./UW• John Schelling/WA EMD• Tim Walsh/WA DNR• Chuck Wallace/Grays Harbor County EM• Gary Chock, Ian Robertson (ASCE 7-16 subcommittee)
Project Team
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Project Site – Westport, WA
Project Site – Westport, WA
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• Incorporate refuge into elementary school– 25’ safe refuge elevation (50’ above MHW)
– 700 students/faculty/staff
– 1000 “total” capacity
– 36,000 sf
• Access & Egress– Security & 24/7 access
– Stairs
– Shelter & supplies
• Limited Budget (~$13m)
Project Scope
• CSZ Scenario– M9– 1,000 km long– 85 km wide– 1-2 m subsidence at site– 8-10 m uplift
• GeoClaw Model – Developed at UW– NTHMP validated
Inundation Modeling
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• Bathymetry
• Topography
• Scour of dunes
• Sea level rise
• Friction coefficient
Site-Specific Inputs
Modeling Resultshmax= 5.3 ft(14.4’ for design)
umax= 3.9 ft/s(10 ft/s for design)
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• Refuge elevation shall be 1-story (3m/10ft) above predicted inundation (with 1.3 uncertainty factor)
• Ocosta – 53 ft. above sea level, 28 ft. above adjacent grade
Minimum Refuge Elevation
• Loose to dense sands• PGA = 0.73 g• Liquefiable to 25 feet
– Plus 5-foot zone near 50 feet
• ½-foot of liquefaction settlement • Lateral spread inconsequential• Scour – 12 feet
Geotechnical Considerations
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• Auger-cast piles (18-inch by 25-foot and 24-inch by 48-foot)
• Six design conditions:– Static, long-term loading without scour– Static loading with scour– Seismic loading with and without scour– Post-seismic, static loading with down drag
(with and without scour)
Foundation Design
• Overturning • Hydrostatic
• Hydrodynamic
• Impact• Logs
• Vehicles
• Progressive collapse
Structural Design
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Safe Refuge Design
Construction
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Foundation Construction
Foundation Construction
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Foundation Construction
Construction
(8) 24” x 50’ piles24” thick pile cap 14” walls
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Construction
Construction
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June 11th Ribbon Cutting
June 11th Ribbon Cutting
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June 11th Ribbon Cutting
June 11th Ribbon Cutting
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June 11th Ribbon Cutting
June 11th Ribbon Cutting
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Questions?