NEESRSG: Development of Performance Based Tsunami Engineering PBTE

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NEESR-SG Development of Performance Based
Tsunami Engineering(PBTE)

• University of Hawaii at Manoa

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Tsunami Engineering
Source Mechanism Tsunami Generation Open Ocean
Propagation Coastal Inundation
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Project Team
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Advisory Panel
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Technical Areas

• Tsunami bore formation/breaking, runup, and
  coastal inundation
• Sediment transport and scour
• Fluid forces on structures
• Structural response to, and design for, tsunami
  loading

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Runup Experiments and Modeling

• Bore formation and breaking
• Effect of fringing reefs and surface roughness
• Energy dissipation
• Bathymetry based on coastal reef environment

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Run-up Experiments
160 ft
runup/reef 15
14 ft
wave propagation
Wavemaker
runup / reef 110
wave propagation
14 ft
runup / reef 115
wave propagation
14 ft
87 ft
New walls
T W B

• Tsunami wave basin will be modified to allow for
  three individual flumes with different bottom
  slopes (July - Dec 2007)

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Run-up Experiments-Constant Slope
resistance wave gauges
gap
piston
2m
ADVs
1m
slopes
115
15
110
18.8m
30m
20m
10m

• Solitary waves with heights from 5cm up to 65cm
• Study bore formation and energy dissipation
• Resistance wave gauges, ADVs, and PIV
• Benchmark tests for bed roughness, fringing reef,
  scour and structural loading

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Run-up Experiments-Fringing Reef
piston
resistance wave gauges
absorber
ADVs
h1
110
15
115
30m

• Fringing reef will be modeled by bi-linear beach
  slopes
• Water level will be varied below, at and above
  the reef flat
• Calibration of shallow water and Boussinesq
  models for wave energy dissipation
• Validation of RANS models for bore breaking

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Run-up Experiments
laser altimeter
high speed camera
piston
absorber

• Laser altimeter will track free surface when air
  entrainment distorts resistance gauges and ADV
  readings
• PIV will monitor transition to white water
• High speed camera will track markers on still
  water and dry bed

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Channels and Beach Slopes

• Develop a modular, reconfigurable system that can
  be used for walls and beach slopes
• FRP panels are promising option
• Long-term asset to the TWB
• Insufficient funding in our project
• Pool with other projects
• Additional funding from NSF/NEES

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Sediment Transport and Scour

• Develop and validate sediment transport and scour
  models
• Enhanced sediment mobility due to excess pore
  pressure
• Role of large scale vortices and bore-generated
  turbulence
• Role of fluid acceleration and deceleration
• Dependence on wave steepness, bed slope, and bed
  roughness

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Sediment Transport ExperimentsLWF
resistance wave gauges
piston
1.5m
1.5m
16
16
ADVs
2m
2m
120
40m
40m
10m
Transducer arrays (bathymetry change) OBS
(sediment concentrations) Pore pressure
transducers

• Monochromatic waves with height at 0.2m increment
  up to 1.6m
• Well-graded sand bed (0.2mm median grain size)
• Preferred instrumentation FOBS (more suitable
  for nearbed sediment concentration measurements)
  for LWF, traverse system for TWB

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Sediment Transport Experiments
piston
2m
1m
110
18.8m
30m
20m
Velocimeter Fiber Optic Backscatter (FOBS) Pore
pressure transducers

• Repeat for 115 bottom slope
• Well-graded sand bed (0.2mm median grain size)

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Sediment Transport Experiments
piston
2m
1m
110
18.8m
30m
20m
Velocimeter FOBS Pore pressure transducers

• Include Plexiglas cylinder to simulate pile

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Fluid Forces on Structures

• Horizontal hydrodynamic loads
• Vertical hydrodynamic loads
• Debris impact loads
• Debris damming loads

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Fluid-Structure Experiments
laser altimeter
high speed camera
piston
absorber
Simple Structure

• Utilize fringing reef setup to produce bore
• Monitor loading on structural elements and simple
  structural systems

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Fluid-Structure Experiments
laser altimeter
high speed camera
piston
absorber
Shipping Container

• Monitor debris damming effects
• Potential payload project to consider woodframe
  structures

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Fluid-Structure Simulation

• Use RANS fluid models with the experimental data
  to improve fluid-structure interaction modeling
• Combination of FLUENT ABAQUS
• Staggered (partitioned) coupling strategy
• Possible use of COMSOL
• Integrated fluid and structure models
  (monolithic architecture)
• SDSC and MHPCC

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Structural Response and Design

• Structural response to hydraulic and impact loads
• Progressive collapse prevention
• Most likely scenario for tsunami
• Prescriptive design
• Code-compatible guidance to design engineers
• Work to implement in codes
• Methodology for site-specific PBTE
• For critical structures

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Performance Levels
Tsunami Wave Height
Maximum Considered Tsunami
Very Rare Events
Design Tsunami
Rare Events
Minor Tsunami
Occasional Events
Vertical evacuation
Collapse Prevention
Immediate Occupancy
Frequent Events
Life safety
Building Performance Level
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Outreach

• Princeton REU program (summer 06)
• Review of existing design guidelines to protect
  coastal structures against erosion and scour
  damage
• Assist with design and setup of scour experiments
• Oregon State University
• Web telecast of all experiments performed in the
  TWB
• Selected experiments will be incorporated into an
  educational webcast for K-12 audience
• University of Hawaii
• Summer 2006 two high school summer interns
  worked on FLUENT modeling
• Enhancement of tsunami display at Bishop Museum

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Education and Outreach

• Bishop Museum - Honolulu
• New Science Adventure Center
• Includes tank showing generation of storm and
  tsunami waves

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Acknowledgments

• This work is supported by the National Science
  Foundation under Grant No. CMS-0530759.
• Any opinions, findings, and conclusions or
  recommendations expressed herein are those of the
  author(s) and do not necessarily reflect the
  views of the National Science Foundation