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Structural Response to Tsunami Loading
The Rationale for Vertical Evacuation
Laura KongIOC ITIC
Ian RobertsonUniversity of Hawaii at Manoa
Harry YehOregon State University
Topics
Pilot Study on current code tsunami design Lessons from Indian Ocean Tsunami FEMA ATC-64 Project NEESR-SG Proposal - Performance Based
Tsunami Engineering, PBTE
Seismic/Tsunami Construction,Phase I: A Pilot Study
Initiated and funded by Washington State Emergency Management Division
One year pilot study Joint effort by OSU and UH Manoa Culminating in development of proposal for
future design guideline development
Project Scope
1. Review current codes for tsunami loading provisions
2. Evaluate prototype structures for seismic/tsunami design
3. Review past tsunami damage
1. Review Current Codes
a. City and County of Honolulu Building Code (CCH)
b. FEMA Coastal Construction Manual (FEMA CCM)
c. Dames and Moore 1980
d. 1997 Uniform Building Code (UBC 97)
e. 2000 and 2003 International Building Code (IBC)
f. ASCE 7-98 and ASCE 7-02 (ASCE 7)
Provisions of codes: • Predominantly intended for residential construction
or small scale structures.• Code provisions developed for storm wave
conditions, storm surge and river flooding.• CCH and FEMA CCM add reference to tsunami
conditions.
FEMA CCM states that : “Tsunami loads on residential buildings may be calculated in the same fashion as other flood loads; when the tsunami forms a borelike wave, the flood velocities are substantially higher.
Conclusion of FEMA CCM: Tsunami loads
are too great and not feasible or practical to design normal structures to withstand these loads.
(Note that this report was intended for use in low-rise residential construction)
Tsunamis covered in CCH and FEMA CCM
Tsunami Design Vs. Design Stillwater Depth
FEMA CCM: Section 11.7 Figure 11-16
Design Considerations
Hydraulic Lateral Forces– full structure – individual elements
Impact Force– floating debris
Buoyancy Force Scour
Design Considerations
Hydraulic Lateral Forces– Hydrostatic– Surge Force– Breaking Wave Force – Hydrodynamic
Impact Force
Design Considerations
Hydraulic Lateral Forces– Hydrostatic– Surge Force– Breaking Wave Force – Hydrodynamic
Impact Force
Design Considerations
Hydraulic Lateral Forces– Hydrostatic– Surge Force– Breaking Wave Force – Hydrodynamic
Impact Force
Design Considerations
Hydraulic Lateral Forces– Hydrostatic– Surge Force– Breaking Wave Force – Hydrodynamic
Impact Force
Design Considerations
Hydraulic Lateral Forces– Hydrostatic– Surge Force– Breaking Wave Force – Hydrodynamic
Impact Force
Design Considerations
Hydraulic Lateral Forces– Hydrostatic– Surge Force– Breaking Wave Force – Hydrodynamic
Impact Force
Impact Force (CCH)
attg
WVFi Δ
= sd
where W = 1000 lbs
t
VFi Δ
=31
Example: Wood Steel RC
VFi 31= VFi 62= VFi 310=
Wood 1.0 secSteel 0.5 secRC 0.1 sec
tΔ Values:
Loading Combinations
If walls not designed to break away:1. Hydrostatic force on building elevation,
plus hydrodynamic force on sides of structure, plus impact force.
2. Breaking wave force on building elevation, plus hydrodynamic force on sides of structure, plus impact force.
3. Surge force on building elevation, plus hydrodynamic force on sides of structure, plus impact force.
Codes call for break-away walls:In-fill wall capacity: min. 10 psf and max. 20 psf
2. Prototype Buildings
Seismic and Wind Design of
Concrete Buildings.
S.K. Ghosh and David A. Fanella
2003.
Includes examples of typical concrete building design for Gravity, Wind and Seismic loading.
Considers various wind exposure conditions and seismic design categories.
Shows sample column, beam and shear wall design.
Building 1 – MRF and Dual System
Building 2 – Building Frame System
Building 3 – Bearing Wall System
Building Design Criteria
Seismic Wind Building Equiv. TsunamiSDC Speed Location Prone Location
A 145 Miami, FL Kauai, HIC 110 New York, NY Oahu & Maui, HI
D 85 San Francisco, CAWest Coast, US;
Hawaii, HI
E 85 Berkeley, CAWest Coast, US;
Hawaii, HI
SDC – Seismic Design Category (Seismic Hazard and Soil Type)
Seismic and Wind Design Criteria
Tsunami Design Criteria
3 Meter Flow Depth
5 Meter Flow Depth
10 Meter Flow Depth
Building 1 ResultsBase Shear Non-break-away walls
KEY SDC A SDC EADEQUATE WIND GOVERNS (145 mph) EQ GOVERNSMARGINAL Entire Structure Entire Structure
INADEQUATE Base Shear (kips) Base Shear (kips)Seismic Forces 291.10 --
N-S Seismic Forces -- 4,690.00E-W Seismic Forces -- 3,162.00N-S Wind Forces 1,493.50 512.70E-W Wind Forces 498.90 171.50
3 Meter Tsunami 6,280.00 6,280.005 Meter Tsunami 17,400.00 17,400.0010 Meter Tsunami 69,700.00 69,700.00
3 Meter Tsunami 2,330.00 2,330.005 Meter Tsunami 6,460.00 6,460.0010 Meter Tsunami 25,800.00 25,800.00
N-S Load Case 2
E-W Load Case 2
Building 1 ResultsBase Shear Break-away walls
KEY SDC A SDC EADEQUATE WIND GOVERNS (145 mph) EQ GOVERNSMARGINAL Entire Structure Entire Structure
INADEQUATE Base Shear (kips) Base Shear (kips)Seismic Forces 291.10 --
N-S Seismic Forces -- 4,690.00E-W Seismic Forces -- 3,162.00N-S Wind Forces 1,493.50 512.70E-W Wind Forces 498.90 171.50
3 Meter Tsunami 1,480.00 1,680.005 Meter Tsunami 4,960.00 5,810.0010 Meter Tsunami 19,800.00 23,200.00
3 Meter Tsunami 2,890.00 3,940.005 Meter Tsunami 8,304.00 11,320.0010 Meter Tsunami 33,100.00 45,200.00
N-S Load Case 1
E-W Load Case 1
Building 1Forces on Structural Members
Column C4 Shear Wall
Building 1 Results
KEYADEQUATE Max Axial N-S Max E-W Max N-S Max E-W Max MARGINAL SDC Force Bending Moment Bending Moment Shear Force Shear Force
INADEQUATE (kips) (ft-kips) (ft-kips) (kips) (kips)
*EQ C 1,507.64 117.82 117.82 21.82 21.82
3 Meter Tsunami C 1,362.76 121.52 121.52 51.08 51.085 Meter Tsunami C 1,362.76 197.93 197.93 83.82 83.8210 Meter Tsunami C 1,362.76 395.88 395.88 167.66 167.66
*EQ D 1,841.45 228.00 386.18 39.27 77.45
3 Meter Tsunami D 1,512.82 132.56 132.56 57.23 57.235 Meter Tsunami D 1,512.82 217.70 217.70 94.43 94.4310 Meter Tsunami D 1,512.82 435.44 435.44 188.86 188.86
*EQ E 2,124.00 273.82 658.91 58.91 140.73
3 Meter Tsunami E 1,641.11 139.37 139.37 62.41 62.415 Meter Tsunami E 1,641.11 229.36 229.36 103.18 103.1810 Meter Tsunami E 1,641.11 458.74 458.74 206.36 206.36
*Governing design of structure
Column
Column – Design ForcesCode Tsunami Forces compared with Seismic Design
Building 1 Results Column - Actual StrengthCode Tsunami Forces vs As-Built Strength
KEYADEQUATE Max Axial Max Bending Max ShearMARGINAL SDC Force Moment Capacity Strength
INADEQUATE (kips) (ft-kips) (kips)
*EQ C 1,507.64 503.00 115.96
3 Meter Tsunami C 1,362.76 121.52 51.085 Meter Tsunami C 1,362.76 197.93 83.8210 Meter Tsunami C 1,362.76 395.88 167.66
*EQ E 2,124.00 1,274.00 365.40
3 Meter Tsunami E 1,641.11 139.37 62.415 Meter Tsunami E 1,641.11 229.36 103.1810 Meter Tsunami E 1,641.11 458.74 206.36
*Governing design of structure
As-Built Column
Building 1 Results Shear Wall - Actual StrengthCode Tsunami Forces vs As-Built Strength
KEYADEQUATE Max Axial E-W Max Bending Max ShearMARGINAL SDC Force Moment Capacity Strength
INADEQUATE (kips) (ft-kips) (kips)
*EQ C 3,112.00 2,386.00 535.58
3 Meter Tsunami C 3,111.98 1,670.81 735.665 Meter Tsunami C 3,111.98 3,249.78 1,557.9310 Meter Tsunami C 3,111.98 8,194.21 3,654.17
*EQ D 4,471.00 7,482.00 1,181.89
3 Meter Tsunami D 3,604.43 1,669.01 748.285 Meter Tsunami D 3,604.43 3,245.03 1,586.6110 Meter Tsunami D 3,604.43 8,141.78 3,710.56
*EQ E 5,135.00 9,912.00 1,601.36
3 Meter Tsunami E 3,899.48 1,600.37 738.175 Meter Tsunami E 3,899.48 3,113.38 1,569.2010 Meter Tsunami E 3,899.48 7,726.59 3,644.41
As-Built Shear Wall
*Governing design of structure
Building 1 Results Shear Wall - Actual StrengthRecommended Tsunami Forces vs As-Built Strength
KEYADEQUATE Max Axial E-W Max Bending Max ShearMARGINAL SDC Force Moment Capacity Strength
INADEQUATE (kips) (ft-kips) (kips)
*EQ C 3,112.00 2,386.00 535.58
3 Meter Tsunami C 3,111.98 768.33 336.885 Meter Tsunami C 3,111.98 1,379.69 584.3210 Meter Tsunami C 3,111.98 2,759.42 1,168.66
*EQ E 5,135.00 9,912.00 1,601.36
3 Meter Tsunami E 3,899.48 734.34 337.615 Meter Tsunami E 3,899.48 1,281.97 576.6810 Meter Tsunami E 3,899.48 2,563.93 1,153.36
*Governing design of structure
As-Built Shear Wall
Conclusions
1. The USA building codes do not adequately address the flow velocity and subsequent structural loading during a tsunami. Experimental validation of the velocity, flow depth and loading expressions is needed.
2. The tsunami forces often exceed the design forces based on wind and seismic conditions
3. However, a review of three typical prototype buildings indicated that the as-built capacity of individual members is often adequate for the tsunami loads
4. The prototype building with moment-resisting frame or dual system was able to resist the tsunami forces
Conclusions (cont.)
5. The prototype building with shear wall-frame system was able to resist the tsunami forces, however individual shear walls perpendicular to the tsunami flow may fail and lead to progressive collapse of the building
6. The prototype building with bearing wall system was not able to resist the tsunami loads and is not recommended for construction in tsunami inundation zones
7. A structure must resist both the initial earthquake ground shaking, as well as the subsequent tsunami loads, so that vertical evacuation can be recommended to levels above the expected maximum flow
Recommendations
1. Analytical Modeling and experimental verification of tsunami flow depth and velocity should be performed using a large-scale wave tank
2. Hydrodynamic force and impact force are the most probable during a tsunami.
3. Wave tank studies should also be performed to verify hydrodynamic loading due to tsunami flow, and impact due to waterborne debris
4. Based on these studies the code tsunami loading equations should be revised.
Recommendations (cont)
5. All non-structural walls at the lower levels should be designed to break-away during a tsunami event
6. Open moment frame or dual systems are recommended for lateral framing of buildings in tsunami inundation areas
7. Buildings in tsunami inundation areas should avoid the use of bearing walls or large structural walls perpendicular to the anticipated tsunami flow
8. Structures must be able to resist the local source earthquake, which often precedes the tsunami, with limited structural damage
Final Recommendation
Vertical evacuation in multi-story reinforced concrete (and structural steel) buildings is an appropriate policy for:
All near-source tsunamis
Remote-source tsunamis in densely populated areas where horizontal evacuation is not feasible
FEMA ATC-64 project
Initiated by FEMA as follow-on to Pilot Study
$400,000 funding for 2-year effort “Development of Design and Construction
Guidance for Special Facilities for Vertical Evacuation from Tsunami”
Applied Technology Council Project Team– Chris Rojahn – Project Executive Director– Steven Baldridge – Project Technical Director
NEESR-SGPerformance Based Tsunami
Engineering, PBTE Proposal to the NSF George E. Brown Network for
Earthquake Engineering Simulation, NEES Small Group project, $1,600,000 over 4-years UH, Princeton, Oregon State University “Development of Performance Based Tsunami
Engineering” Will include numerous tsunami wave basin
experiments to validate run-up and 3-D RANS modeling, develop improved loading time-history, scour modeling and structural response.
Result in code adoptable tsunami design provisions
HOTELWAIKIKI
Thank-you