Project Listing

Current

  1. Collaborative Research: Nonlinear Long Wave Amplification in the Shadow Zone of Offshore Islands (Phase I)
  2. Collaborative Research: Fundamental Mechanics and Conditional Probabilities for Prediction of Hurricane Surge and Wave Loads on Elevated Coastal Structures
  3. Probabilistic Assessment of Tsunami Forces on Coastal Structures
  4. Collaborative Research: Numerical and Probabilistic Modeling of Aboveground Storage Tanks Subjected to Multi-Hazard Storm Events
  5. Collaborative Research: Nonlinear Long Wave Amplification in the Shadow Zone of Offshore Islands (Phase II)
  6. SBIR Phase I: Telescopic Structural Flood Walls
  7. CAREER: Advancing Multi-Hazard Assessment and Risk-Based Design for Offshore Wind Energy Technology
  8. Transient Rip Current Dynamics: Laboratory Measurements and Modeling of Surfzone Vorticity
  9. Collaborative Research: Physical Modeling of Submarine Volcanic Eruption Generated Tsunamis
  10. Runups of Unusual Size: Predicting Unexpectedly Large Swash Events

Upcoming

  1. Collaborative Research: Wave, Surge, and Tsunami Overland Hazard, Loading and Structural Response for Developed Shorelines
  2. Vertical Evacuation Structures Subjected to Sequential Earthquake and Tsunami Loadings
  3. Collaborative Research: Physics of Dune Erosion during Extreme Wave and Storm-Surge Events

Current Project Details  

Collaborative Research: Nonlinear Long Wave Amplification in the Shadow Zone of Offshore Islands (Phase I)

CMMI 1538190 – PI James Kaihatu, Texas A&M

2016-Q3. Resource: Directional Wave Basin

Field survey reports from recent tsunamis suggest that local residents in mainland areas shadowed by nearby islands may be under the impression that these islands protect them from tsunamis. Recent numerical results using the mathematical procedure known as "active learning" have generated substantial attention in world media (The Economist, Der Spiegel, Science, Korean Herald, Kathimerini), because they suggest that, in most cases, islands amplify tsunamis in the shadow zones behind them. In this application, the active learning methodology requires about 100,000 times fewer computations than conventional mathematical approaches, and it is unclear if the amplification effect is real. Through comprehensive laboratory experiments, the physical manifestation of this effect will be studied. If indeed the physical experiments confirm the numerical idealizations, this research will help save lives by better targeting educational campaigns to at risk populations. For example, it will be determined if coastlines shadowed by offshore islands along the Pacific Coast of the US are more vulnerable than earlier believed.

The early numerical results from active learning are only applicable for non-breaking waves. While many existing numerical codes attempt to model mild long-wave breaking, as they sometimes do, it is unclear how well they perform when scattered long waves break and interact. It is equally unclear if the isthmus between islands scatters the wave energy or focuses further in the mainland behind them, or under what geographical conditions either effect prevails. Through the laboratory experiments, it will be determined if this vexing phenomenon persists when waves break. The results will help validate active learning as a mathematical procedure for uncertainty reduction which greatly reduces computational costs. Also, a substantial laboratory data set will be developed to help benchmark numerical computations for interacting breaking wave fronts, under conditions as yet unstudied. An outreach campaign is planned to educate populations at risk and improve the awareness of emergency managers on this unusual amplification phenomenon. 

Collaborative Research: Fundamental Mechanics and Conditional Probabilities for Prediction of Hurricane Surge and Wave Loads on Elevated Coastal Structures

CMMI 1301016 – PI Dan Cox, Oregon State University

2016-Q3, Q4. Resource: Large Wave Flume

Damage to coastal structures as a result of combined surge and wave loading has been significant in recent events such as Hurricane Ivan (2004), Katrina (2005) and Ike (2008) and most recently Sandy (2012). There is over $3T in built infrastructure along the US East and Gulf coasts, and elevated structures along coastal areas are becoming more commonplace as building stakeholders seek to mitigate damage and risk of property and structure loss. Currently, there are no accurate mechanics equations to compute the forces for combined surge and wave on these types of elevated structures and no comprehensive method to consistently account for the variability (uncertainty) in the random nature of the incoming waves. This project will pursue research that focuses on the impact of hurricane surge and wave loads on elevated coastal structures. The ultimate goal is to understand and quantify surge and wave loads on buildings and structures that can be used to mitigate damage to the coastal structures. A theoretical approach based on physics will be used to model the interaction between the water and coastal structure. The analytical formulation will be validated through small scale experimental testing in a wave tank. Storm surge and wave impacts will be formulated on a probabilistic basis. The results of the research can lead to performance based requirements in building standards.

This collaborative project between research teams at Oregon State University and Colorado State University will combine expertise in coastal engineering and structural engineering to develop a fundamental understanding and modeling of hurricane surge and wave loads on elevated structures. The goal is to mitigate damages to shoreline infrastructures from extreme coastal storms. The analytical formulation will be built on Goda's method for calculating surge forces on elevated coastal structures and will be extended to incorporate wave forces. A probabilistic approach will be taken to combine surge and wave loads. Hydrodynamic hurricane wave and structure interaction will be used to formulate loading on these types of structures. The formulation will be validated with experiments on small scale structure models using a wave tank. The collaborative project will contribute to understanding of wave and surge loads and develop predictive equations for uplift, impact and overturning loads on elevated structures. 

Probabilistic Assessment of Tsunami Forces on Coastal Structures

CMMI 1536198 – PI Mike Motley, University of Washington; co-PI Randall LeVeque and Frank Gonzalez, University of Washington

2016-Q4, 2017-Q1. Resource: Large Wave Flume

In the last decade, tsunamis have caused hundreds of thousands of deaths and hundreds of billions of dollars in damage to coastal communities around the world. While a major tsunami has not impacted the United States in some time, there is significant risk to the Pacific Coast and recent storm surge events have shown a potential for damage to domestic infrastructure similar to what was seen in East Asia and the Pacific. Interest in tsunami load predictions for structural design has grown, but it is difficult to develop models that accurately predict the tsunami load response of an individual structure, much less the tsunami risk for multiple structures within a specific region. The framework presented here is designed to improve the safety and sustainability of coastal structures and, consequently, improve tsunami hazard assessments, post-event response, and recovery efforts. Ultimately, this work will result in safer communities through increased public awareness of the risks posed by these types of hazards and enhanced tools to develop resilient infrastructure systems.

Increased computing power has prompted the development of novel numerical approaches to tsunami-structure interaction modeling tailored to capture specific physical phenomena with high-levels of resolution and accuracy, including coupled multiphysics models to simulate complex system interactions. If community-specific assessments of structural vulnerabilities are to be achieved, they must be based on a fundamental understanding of these interactions and an ability to efficiently model the associated physical processes in a probabilistic framework that accounts for the uncertain nature of these events. The primary goals of this research project are to establish an open-source modeling framework where 3D computational fluid dynamics solvers can be used efficiently to inform the development of load-prediction capabilities for existing, widely used inundation models and to develop a probabilistic framework for predicting the fluid loading and structural response of coastal structures at a community level. The research team will validate this framework against existing experimental data, assess the effects of bathymetry and community layout on flow, refine the models to include force predictions, and extend probabilistic tsunami hazard assessment methods to include fluid loading criteria. This work will provide users both the framework and the software tools necessary to develop site-specific numerical models to increase the safety and sustainability of coastal structure by improving our understanding of the probabilistic risk posed by tsunami events on these structures. 

Collaborative Research: Numerical and Probabilistic Modeling of Aboveground Storage Tanks Subjected to Multi-Hazard Storm Events

CMMI 1635784 – PI Jamie Padgett, Rice University

2017-Q1, Q2. Resource: Directional Wave Basin

Aboveground storage tanks (ASTs) used to store hazardous materials, such as crude oil, can suffer major damage in severe storms resulting in spills with catastrophic social, environmental, and economic consequences. Failure of these structures has been attributed to flotation, buckling, or damage from debris. Despite significant evidence of tank vulnerability and consequences of failure, understanding of the mechanisms leading to AST failure under multiple storm-induced hazards (e.g., surge, wave, wind) is limited. This research will address such gaps by providing numerical models that are capable of capturing the complex fluid-structure interaction (FSI) and nonlinear system behavior exhibited by ASTs under multi-hazard loads. Furthermore, probabilistic models of tank performance in severe storms will be developed, filling a major gap in risk assessment of this critical industrial and energy infrastructure. The advanced computational resources and collaboration and analysis tools of the National Science Foundation-supported Natural Hazards Engineering Research Infrastructure (NHERI) cyberinfrastructure, DesignSafe-CI.org, will be utilized and enhanced in this effort. Through this research, open source codes and probabilistic tools will be provided to better understand the public's risk of being exposed to hazardous spills with far reaching environmental and social impacts. To support risk reduction efforts, viable strategies to avoid such spills are investigated and disseminated to relevant stakeholders in addition to the scientific community. Along with the contribution of open source computer models to the natural hazards engineering community, this project will provide training materials and demonstration applications of DesignSafe-CI functionalities that can be used for education and community outreach on cyberinfrastructure-enabled research.

This project will harness the synergies of a multi-disciplinary team spanning computational sciences and structural engineering to provide robust numerical models of AST response under multi-flow conditions and to subsequently derive the first models of AST fragility under multiple storm-induced hazards. The project's research and educational objectives include: 1) advanced numerical modeling of FSI with emphasis on surge, wave, and wind impacts on ASTs; 2) derivation of multi-hazard flotation and buckling fragility models for ASTs in the presence of local and global imperfections; 3) case study analysis of a portfolio of tanks with the developed numerical and probabilistic models and dissemination of lessons learned; and 4) development of learning modules on cyberinfrastructure-enabled multi-disciplinary teaming for the natural hazards engineering community. To meet these objectives, open source, multi-physics software will be developed to capture complicated multi-phase flow scenarios and also allow for streamlined analysis of regional storm simulations with localized FSI response modeling. Numerical simulation with the resulting codes will provide new insight into the response of ASTs subjected to surge, wave, and wind and enable sensitivity and fragility analysis for flotation and buckling failure modes across a range of uncertain hazard and structural parameters. Given the computational complexity of simulating associated AST behavior, statistical surrogate models will be derived based on the numerical FSI simulations. This strategy is expected to render efficient limit state analysis for fragility modeling of ASTs feasible for the first time under surge, wave, and wind and address a major gap in risk assessment of ASTs. The resulting parameterized formulations will be amenable to sensitivity analyses and ready application to a portfolio of tank infrastructure, which will be tested through a case study in the Houston, Texas region. 

Collaborative Research: Nonlinear Long Wave Amplification in the Shadow Zone of Offshore Islands (Phase II)

CMMI 1538624 – PI Costas Synolakis, U. Southern California; co-PI Patrick Lynett, U. Southern California

2017-Q2, Q3. Resource: Directional Wave Basin

Field survey reports from recent tsunamis suggest that local residents in mainland areas shadowed by nearby islands may be under the impression that these islands protect them from tsunamis. Recent numerical results using the mathematical procedure known as "active learning" have generated substantial attention in world media (The Economist, Der Spiegel, Science, Korean Herald, Kathimerini), because they suggest that, in most cases, islands amplify tsunamis in the shadow zones behind them. In this application, the active learning methodology requires about 100,000 times fewer computations than conventional mathematical approaches, and it is unclear if the amplification effect is real. Through comprehensive laboratory experiments, the physical manifestation of this effect will be studied. If indeed the physical experiments confirm the numerical idealizations, this research will help save lives by better targeting educational campaigns to at risk populations. For example, it will be determined if coastlines shadowed by offshore islands along the Pacific Coast of the US are more vulnerable than earlier believed.

The early numerical results from active learning are only applicable for non-breaking waves. While many existing numerical codes attempt to model mild long-wave breaking, as they sometimes do, it is unclear how well they perform when scattered long waves break and interact. It is equally unclear if the isthmus between islands scatters the wave energy or focuses further in the mainland behind them, or under what geographical conditions either effect prevails. Through the laboratory experiments, it will be determined if this vexing phenomenon persists when waves break. The results will help validate active learning as a mathematical procedure for uncertainty reduction which greatly reduces computational costs. Also, a substantial laboratory data set will be developed to help benchmark numerical computations for interacting breaking wave fronts, under conditions as yet unstudied. An outreach campaign is planned to educate populations at risk and improve the awareness of emergency managers on this unusual amplification phenomenon. 

SBIR Phase I: Telescopic Structural Flood Walls

IIP 1621727 – PI Jorge Cueto, Smart Walls Construction LLC

2017-Q2. Resource: Directional Wave Basin and Large Wave Flume

This Small Business Innovation Research Phase I project is aimed to develop, test and validate a retractable telescopic structural wall for applications in flood protection. This technology will enable more resilient infrastructure in flood-prone areas. Climate change is creating a problem for coastal cities and local communities in proximity to large bodies of water. Population centers tend to be located near such bodies of water, and finding the space to accommodate increasing populations, as well as hazard-resilient infrastructure, represents a challenge for city officials and the engineering community in general. The addressable market size for this technology is estimated at $2.6 billion. The proposed concept, when validated, will provide a paradigm shift for the prefabricated concrete industry. It will also develop and validate new methods for telescopic interconnection of structural elements.

The intellectual merit of this project lies in a unique concept where structural boxes, made out of fiber reinforced concrete, can be deployed telescopically to withstand forces imposed from external sources, and then return to a retracted position. The goals of the proposed research surround the detailed design of the mechanisms, determination of a geometric configuration and material mix to achieve a high strength-to-weight ratio, and the execution of laboratory experimentation and field tests on physical working prototypes. The plan to accomplish these goals starts with the development of numerical simulations and an analytical framework. Results will be validated via laboratory tests where lateral and vertical loads, as well as impact loads, will be applied. Field tests of the specimens will also be conducted to determine the effects of soil type on performance. These field tests will serve as well to simulate realistic still flood water conditions. The anticipated technical result of Phase I is a working prototype of the telescopic structural flood wall with extension and retraction capabilities, and with the structural capability to withstand the forces from flood events with minimal to no damage. 

CAREER: Advancing Multi-Hazard Assessment and Risk-Based Design for Offshore Wind Energy Technology

CMMI 1552559 – PI Andrew Myers, Northeastern University

2017-Q4, 2018-Q1. Resource: Large Wave Flume

Offshore wind energy is a resource of renewable energy that is conveniently accessible to many major population centers, but harvesting offshore wind energy currently costs more than traditional sources. The research goal of this Faculty Early Career Development (CAREER) Program grant is to advance knowledge that can lead to reduction in the cost of offshore wind energy through (1) a much sharper understanding and modeling of the spatio-temporal interaction of multiple offshore hazards that impact the system-level performance of offshore wind energy farms to reduce insurance and financing costs, (2) the calculation of novel system-level performance metrics, and (3) the advancement of shallow water wave modeling to mitigate the current reliance on overly conservative design methods. The educational goals of this project are to leverage field experiences at state-of-the-art offshore wind-themed sites in New England to inspire high school students to pursue science, engineering, mathematics, and technology careers and to transfer knowledge of multi-hazard assessment and design to the public, other researchers, and the practicing engineering community.

This project will achieve the research goal through fundamental advancements to metamodels (surrogate models) to overcome restrictions that have previously limited the impact of such models in the context of multi-hazard assessment of spatially-distributed infrastructure. Specifically, novel metamodels will be developed to include several important features, such as spatio-temporally varying hazards, high-dimensionality of the input and output vectors, explicit accounting of model adequacy by quantifying inter- and intra-event uncertainty in the model predictions compared to measurements, and a coupling of multi-hazard and system/structural metamodels. The research will also explore innovative models that overcome important deficiencies in the modeling of nonlinear, highly skewed shallow water waves and their associated hydrodynamic loads, including breaking waves. The research will synthesize these advances and generate system-level performance metrics that will provide a fundamentally different paradigm for designing offshore wind farms. The project will leverage partnerships with state, city, academic, and industry organizations. The research outcomes are expected to have broad impact beyond the offshore wind industry, given the national needs in multi-hazard analysis and infrastructure system resilience, and the potential of metamodeling applications in civil engineering and other fields. 

Transient Rip Current Dynamics: Laboratory Measurements and Modeling of Surfzone Vorticity

OMI 1735460 – PI Nirnimesh Kumar, University of Washington; Melissa Moulton, University of Washington

2018-Q1, Q3. Resource: Directional Wave Basin

The nearshore region, valued as essential intertidal habitat and recreational grounds, is often compromised by pathogens and excess nutrient supply from terrestrial runoff. When an area becomes contaminated, beach closures, ecological disruption, and associated economic losses can result. Understanding the transport of materials throughout the nearshore region can have important implications for ecosystem and human health. Previous studies analyzing cross-shelf exchange suggest that transient rip currents are the dominant mechanism driving exchange between the surf zone and the inner shelf. Evidence also suggests that transient rip currents are generated from the coalescence of surf zone eddies, with short-crested waves serving as the source of rotation. This project will utilize a laboratory and numerical modeling to study the generation and evolution of surf zone eddies to form transient rip currents. The knowledge of mixing and exchange in the nearshore region will be significantly advanced through this study, which will have important implications for the transport of nutrients, larvae, and pollutants. In collaboration with National Oceanic and Atmospheric Administration scientists, simple predictors of transient rip currents will be developed to improve hazard forecasts for a broad range of environments. This is essential information for human safety as rip currents are the leading cause of fatalities and rescues on beaches. A graduate student will gain valuable training and education through involvement in this project. Outreach activities highlighting rip currents will be developed as a part of the O.H. Hinsdale Wave Research Laboratory Outreach Program seeking to broaden participation in Science, Technology, Engineering and Mathematics (STEM).

This project seeks to establish a cradle-to-grave picture of the injection of eddies into the surf zone by short-crested wave breaking, coalescence to form larger eddies, and formation of transient rip currents. The overall objective is to determine if the surf zone can be treated as a two-dimensional turbulence box. This study will improve understanding of the dynamics of surf zone eddy generation and evolution leading to transient rip currents and associated cross-shelf exchange by addressing four specific hypotheses: 1) short-crested waves are an important vorticity source at short spatial and temporal scales, 2) smaller eddies coalesce to create bigger eddies, 3) surf zone eddy decay is controlled by bottom friction, and 4) eddies ejected outside of the surf zone onto the shelf deviate from the two-dimensional paradigm. Laboratory experiments will include in situ and remote (stereo visible and infrared) measurements of sea-surface-elevations and velocities for a range of wave heights, periods, and directional spreads. State-of-the-art numerical modeling will be used to guide laboratory sampling, to analyze dynamics for a range of conditions, and to assess the importance of frictional dissipation and three-dimensional circulation properties. If the surf zone can be treated as a forced two-dimensional turbulence box, simplified models with appropriate forcing can be established to advance the understanding of the role of the surf zone in land-to-sea transport. 

Collaborative Research: Physical Modeling of Submarine Volcanic Eruption Generated Tsunamis

CMMI 1563217 – PI Hermann Fritz, Georgia Tech; Josef Dufek, Georgia Tech

2018-Q2, Q3. Resource: Directional Wave Basin

Tsunamis are normally associated with submarine earthquakes along subduction zones, such as the 2011 Japan tsunami. However, there are significant tsunami sources related to submarine volcanic eruptions. Volcanic tsunamis, like tectonic tsunamis, typically occur with little warning and can devastate populated coastal areas at considerable distances from the volcano. There have been more than 90 volcanic tsunamis accounting for about 25% of all fatalities directly attributable to volcanic eruptions during the last 250 years. The two deadliest non-tectonic tsunamis in the past 300 years are due to the 1883 Krakatoa eruption in Indonesia with associated pyroclastic flows and Japan's Mount Unzen lava dome collapse in 1792. At the source, volcanic tsunamis can exceed tectonic tsunamis in wave height, but these volcanic tsunamis are subject to significant wave attenuation and dispersion with propagation distance. There are at least nine different mechanisms by which volcanoes produce tsunamis. Most volcanic tsunami waves have been produced by extremely energetic explosive volcanic eruptions in submarine or near water surface settings, or by flow of voluminous pyroclastic flows or debris avalanches into the sea. The recent "orange" alert in July 2015 at the Kick 'em Jenny submarine volcano off Granada in the Caribbean Sea highlighted the challenges in characterizing the tsunami waves for a potential submarine volcanic eruption. In this work we will conduct a suite of experiments and closely linked modeling efforts to quantify the relationship between source eruptive mechanism and wave generation. This research will serve assessment and mitigation of coupled volcanic and tsunami hazards.

The ultimate long-term goal of this research is to transform assessment and mitigation of the submarine volcanic tsunami hazard through hybrid modeling of submarine volcanic eruption, tsunami generation and propagation along with the potential engulfment and caldera formation. Critically important data related to these submarine tsunami generation processes is lacking in the literature. This research will compensate for missing data by hybrid modeling of 3D submarine volcanic eruption tsunami generation scenarios. It will focus on the tsunami generation by submarine volcanic eruptions and engulfments. A computer controlled pneumatic submarine volcanic eruption tsunami generator (SVE-TG) will allow fully 3D physical modeling. The variable eruption velocities of the SVE-TG mimic relatively slow mud volcanoes and rapid explosive eruptions. The event analysis will be used to determine the experimental program and the design of the SVE-TG, which will expand the capabilities of the existing NHERI tsunami facilities. The experimental program will determine the characteristics of the dynamic eruptive column and the coupled tsunami generation, propagation and potential caldera formation. The combined experimental results from the submarine volcanic eruption will provide a robust validation tool for numerical models of submarine volcanic eruptions and engulfments. Source characteristics from submarine volcanic eruption events remain poorly constrained from present experimental and numerical studies. A historical event will be simulated by using described coupled volcanic mass flow, eruption and tsunami mechanisms. This research will transform knowledge and understanding of submarine volcanic tsunamis and potentially mitigate some of the deadliest non-tectonic tsunami hazards. 

Runups of Unusual Size: Predicting Unexpectedly Large Swash Events

OCE 1459049 – PI H. Tuba Ozkan-Haller, Oregon State University; co-PI Peter Ruggiero and Robert Holman , Oregon State University.

2018-Q2, Q4. Resource: Large Wave Flume

The goal of this project is to improve our understanding of unusually large wave runup events on ocean beaches. Such runup events are seen with only a small fraction of the waves, yet they are important for the prediction of dune erosion, inundation and coastal flooding during storms. A second type of unusual runup event is also distinguished in that it is sudden and unexpected even if the landward reach of the runup is not a statistical extreme. These large and unusual runup events are the leading cause of death by drowning along the U.S. Pacific Northwest. In order to understand the causes of unexpectedly large runup events, and to begin to forecast their potential occurrence, this project will use existing data, a new multi-year data set and a hierarchy of numerical model simulations and link the events to various generation mechanisms. Finally a model will be developed and tested for forecasting the risk of such events. The team will work with the National Weather Service offices as well as exploring other outlets to communicate severe event forecasts to the public. In addition to increased public safety, this project will also help coastal management efforts. These efforts rely on predictions to outline flood hazard zones and regions appropriate for development. Additionally, findings from the numerical modeling portion of the study will document and potentially advance the accuracy/capabilities of nearshore hydrodynamic models, which will benefit coastal zone management in other geographic settings. Finally the project will contribute to education efforts by directly involving graduate and undergraduate students in the research, paying specific attention to the entrainment of individuals from under-represented groups.

The study of swash zone hydrodynamics has seen sustained progress over the last decade, with much of the focus on the characterization of bulk and extreme runup statistics. However, the physical causes of large, and especially of unexpected, events have received considerably less attention. This project will conduct data collection and analysis and numerical model studies designed to distinguish between linear generation mechanisms related to super-position and nonlinear generation mechanisms related to bore-bore capture, incident wave-infragravity wave interactions and uprush-backwash events for large as well as unexpected runup events. Morphodynamic differences between two drastically different beaches, Agate Beach, OR and Duck, NC, will help reveal the role of beach type on the generation of both large and unusual runup events. The observations will allow the team to test and improve the skill of simple extreme runup parametric models during storms.


Upcoming Project Details 

Collaborative Research: Wave, Surge, and Tsunami Overland Hazard, Loading and Structural Response for Developed Shorelines

CMMI 1661015 – PI Andrew Kennedy, Notre Dame; co-PI Patrick Lynett, U Southern California; co-PI R. Gahnem, U Southern California; co-PI Andre Barbosa and Dan Cox, Oregon State University

2018-Q4, 2019-Q1. Resource: Directional Wave Basin and Large Wave Flume

Inundation from storms like Hurricanes Katrina and Sandy, and the 2011 East Japan tsunami, has caused catastrophic damage to coastal communities. With increasing coastal population, and trillions of dollars of infrastructure at risk, storms and tsunamis will continue to be threats to coastal communities. Improving community resilience to these Inundation Events (IEs) requires an understanding of how they damage buildings. Prediction of structural damage in IEs can be quite difficult along developed shorelines, where some structures may partially shield buildings behind them, reducing damage in ways that are not easily predictable using the existing state-of-the-art. This project will create new tools to predict structural damage from IEs along developed shorelines. The team from the University of Notre Dame, Oregon State University, and the University of Southern California will develop computer-based predictive methods for detailed building damage using laboratory tests and field data to guide development and validate accuracy. These new models will provide increased inundation and damage prediction accuracy, resulting in improved community resilience efforts and more efficient building design. Input from industry and professional standards committees will ensure that these results reach engineering practitioners.

Prediction of surge, wave, and tsunami flow transformation over the built and natural environment is essential in determining survival and failure of near-coast structures during Inundation Events. However, unlike earthquake and wind hazards, IE loading and damage often vary strongly at a parcel scale in built-up coastal regions due to the influence of nearby structures on hydrodynamic transformation. Additionally, IE hydrodynamics and loading are presently treated using a variety of simplified methods (e.g. bare earth method) which introduce significant uncertainty and/or bias. Furthermore, existing evaluations of structural damage during IEs do not employ standard structural techniques, in large part because of uncertainties in the hydrodynamics and loading. This collaborative project will examine probabilistic structural vulnerability to storm waves and tsunamis in developed regions, where structures are most concentrated but existing models perform poorly due to complex flow transformation around these structures. The laboratory and computational methodologies developed here will employ deterministic and stochastic models with scales able to resolve local transformation, and that directly represent relevant processes. Resolving the local transformation at fine scales will provide improved accuracy in the prediction of structural vulnerability during IEs, enabling improved design, mitigation, and risk-informed decision making. Results of the detailed methodology, which will be computationally intensive, will be used where appropriate to develop more tractable methodologies for the probabilistic prediction of hydrodynamic transformation, loading, and structural response by engineering practitioners. 

Vertical Evacuation Structures Subjected to Sequential Earthquake and Tsunami Loadings

CMMI 1726326 – PI Dawn Lehman, University of Washington; Pedro Arduino, Michael Motley and Charles Roeder, University of Washington

2019. Resource: Large Wave Flume

In extreme events, such as major earthquakes or tsunamis, public safety is a primary concern. A major subduction zone earthquake could cause a large tsunami, which could render constructed infrastructure near the coastline, traditionally designed for only seismic loads, to be severely damaged and result in loss of life. In coastal regions at low elevations, it may be difficult to quickly move to higher ground in the short time between the initial ground shaking and the arrival of a tsunami from a subduction earthquake. However, a vertical evacuation structure (VES) could provide refuge, with the most promising VES for large coastal populations being buildings with lower stories capable of resisting the sequential earthquake demands and tsunami loads. This research will investigate a new structural system for a building to serve as a VES, where the structural elements are continuous from the end of the pile to the top of the structure. This new system will use the above-wave-height stories for evacuation; the lower (below wave) stories will use connections that allow walls and slabs of the lower, non-evacuation floors to "breakaway" at the highest water level. Although counterintuitive, this breakaway system will reduce the tsunami load demands on the structure, further protecting the building and its occupants. This research will investigate the interactions of the structure, soil, and tsunami waves for both traditional systems designed only for seismic loads and the new breakaway structural system. The results of this research will provide first-of-its kind data for this new type of VES, which can improve life safety in tsunami-prone regions and provide course-ready material for graduate-level classes and seminars for researchers and practitioners. Data from the project will be archived and made publicly available in the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) Data Depot (http://www.designsafe-ci.org).

Although evacuation structures have been built in tsunami-prone regions in Japan and the United States, they are typically low-rise structures with limited shelter capacity. In contrast, taller structures could serve dual purposes, such as a hotel with lower stories housing retail or conference rooms, with upper levels designed for evacuation. Under earthquake loading, buildings are expected sustain damage in the maximum credible event and, unless specific to the site, soil-structure interaction is neglected. This design philosophy would not serve for a VES, which must be designed to: (1) remain damage-free during the maximum credible earthquake, (2) sustain the maximum considered tsunami at the lower floors, including horizontal and vertical forces, where initial research shows that these tsunami force demands can be two to five times the design earthquake forces, and (3) account for changes in the stiffness and strength of the soil due to liquefaction and scour. This research will address the fundamentals of sequential earthquake and tsunami hazard building performance to serve as a VES, accounting for full nonlinear soil-structure-wave interaction. Two structural systems will be studied: exterior concrete walls, which are a traditional structural solution for seismic loads, and a new structural system utilizing continuous concrete filled tube pile-column frames with breakaway connections at the floors below the inundation depth, tuned to fracture at specific loading resulting from hydrostatic buoyancy. The research activities will involve the following: (1) investigate fundamental characteristics of the soil-structure system through computational simulation, (2) experimentally study tsunami demands on the structure using the NHERI Large Wave Flume at Oregon State University, (3) analytically couple the tsunami demand and structure-soil response analyses using the NHERI Computational Modeling and Simulation Center resources, and (4) combine the findings to evaluate current and establish new design methodologies for VESs subjected to sequential earthquake and tsunami hazard loading. 

Collaborative Research: Physics of Dune Erosion during Extreme Wave and Storm-Surge Events

OCE 1756449- PI Dan Cox, Meagan Wengrove, Oregon State University; Jack Puleo, Tom Hsu, U Delaware; Rusty Feagin, TAMU

2019-Q2, Q3. Resource: Large Wave Flume

Sand dunes are often the primary and sometimes only 'line of defense' for coastal infrastructure, and are increasingly constructed and actively managed to protect against extreme events. Coastal managers require knowledge of how dunes will respond under these events so assets can be pre-positioned. Both natural and constructed dunes dissipate energy by modifying breaking waves and runup to limit overwash, thereby minimizing coastal flooding during extreme waves and storm-surge events. However, because extreme physical forces only interact with the dune for a relatively short, yet critical time when the water level rises, there is limited understanding on how dune sediments and vegetation can modify hydrodynamic forces and alter beach-dune profile evolution. This research focuses on dune response to a range of water level and forcing conditions that mimic the passage of an extreme storm event. A near prototype-scale laboratory experiment will be conducted over a mobile bed in the large wave flume at Oregon State University. Physical model studies will occur over a bare dune, a rapidly constructed (loosely compacted) dune following wave-induced erosion, and a dune with live vegetation. Data related to processes ranging from short-term (turbulence) to longer time scales (individual events) will be collected and analyzed to develop a fundamental understanding of the fluid-sediment-vegetation dynamics affecting dune stability, as well as damage mitigation strategies for extreme events. The collected data will be used to validate numerical models.

A multiphase flow model sedwaveFoam (created in the open-source OpenFOAM framework), capable of simulating the full profiles of sediment transport under realistic waves, will be extended for dune erosion with or without vegetation. Detailed simulations will further inform the creation of improved parameterizations of turbulence- and wave-scale processes in the event-scale morphodynamic model XBeach. A fragility framework, consistent with risk-based decision support tools, will be created to predict the probability of damage states (e.g., dune volume loss) for a given level and duration of hydrodynamic forcing. The collected data and extensive XBeach simulations will provide required input parameters for the fragility analysis. The data and modeling for different dune archetypes will be used to: (i) identify the fundamental processes (including waves, turbulence, and sediment transport) that drive dune evolution during extreme events; (ii) define the conditions by which dune vulnerability increases as function of berm erosion; (iii) investigate the interaction between the different processes and identify the threshold forcing conditions and time scales beyond which vegetation no longer enhances dune resilience; and (iv) examine the extent a fragility modeling framework can be used to improve risk-based decision for dune erosion during extreme surge and wave events. Natural resource managers and practicing engineers with on-the-ground experience, from Federal and State (Delaware, Texas) levels will contribute to this project through a stakeholder workshop planned for year 3. The fragility framework will be developed in collaboration with managers from Delaware and Texas, allowing prediction of dune damage based on commonly used measures of storm intensity. The project will support PhD and undergraduate students.