Program

This lecture will focus on exploring the influence of turbulence, damping, noise and correlation in stabalizing the dynamics of systems of mechanical, electrical, aerodynamic, hydrodynamic and other origins. Added damping in a structural system tends to tame its behavior by lessening the amplitude of motion. Along the same lines, turbulent fluctuations in the approach flow field upon interacting with a structure like a building or a bridge lead to aerodynamic pressure fluctuations replicating those present in the inflow field and at additional frequencies ensuing from nonlinear aerodynamic features. These fluctuations in the regions where flow does not remain attached to the structure (surfaces parallel to the flow) have been observed to fade in the presence of added turbulence in the inflow. These trends are manifested by way of dampening the instabilities in the separated flow regions around the building that leads to vitiating the enveloping flow field energetics and hence the aerodynamic forces. This is similar to adding damping to the flow field fluctuations resulting in a reduction in loads and hence building response. Similarly, noise is known to influence the dynamics of nonlinear systems by influencing the onset of bifurcation behavior, stability and the transition to chaos. The lack of correlation structure, e.g., in fluid (wind & waves) structure interaction tends to reduce the integrated load effects. The lack of correlation may be due to the nature of approach flow field and any asymmetry in it, e.g., turbulence and directional seas and variations in the profile of the form of building/bridge profile. In numerical simulation of flow fields often introduction of damping through different means tends to dampen out high frequency fluctuations. This note briefly discusses the analogous role of damping, turbulence, correlation and noise in taming the behavior of dynamic systems based on the notion that everything is a “harmonic oscillator” and mutual interactions among them manifest vicissitudes in the system dynamics! These can be viewed as virtual harmonic oscillators that facilitate simple-to-understand analogs that conceptually capture the complexity otherwise couched in a complex system of equations. The role of these features on the virtualization of systems, making sense out of sensing, and issues surrounding the three “nons,” i.e., nonlinearity, non-Gaussianity and non-stationarity will be discussed.

NatHaz Modeling Laboratory
University of Notre Dame
www.nd.ed/~nathaz
https://en.wikipedia.org/wiki/Ahsan_Kareem

Ahsan Kareem, Dist. FASCE, NAE, is the Robert M. Moran Professor of Engineering in the Department of Civil & Environmental Engineering and Earth Sciences (CEEES) at the University of Notre Dame. He served as the President of the American Association of Wind Engineering (AAWE) and International Association of Wind Engineering (IAWE). The focus of his work is on quantifying load effects caused by various natural hazards on structures and to develop innovative strategies to manage and mitigate their effects. This includes characterization and formulation of dynamic load effects due to wind, waves and earthquakes on tall buildings, long-span bridges, offshore structures and energy related structures that is carried out via fundamental analytical computational methods, and experiments at laboratory, and full-scale. He directs NatHaz Group (NatHaz Modeling Laboratory) which focuses on developments in cyberspace virtual collaborative research platforms, e.g., virtual organizations, IoT, edge computing, crowdsourcing, computational intelligence, living laboratories, sensing and actuation, citizen sensing, web-enabled analysis and design, scientific machine learning (SciML) and cloud-based computing to address challenges posed by natural hazards to the built environment.

Resilience is the ability to prepare for, adapt to, and recovery rapidly from hazards such as tornadoes and hurricanes. The ability to model a community necessitates combining models from different disciplines including their interfaces, the propagation of uncertainty, and ultimately the measurement of resilience metrics across physical systems, households, social institutions, and the economy. This presentation will begin with a very brief summary of the history of community resilience research in the United States, quickly moving to the state-of-the-research in interdisciplinary resilience modeling of communities and cities to extreme wind hazards such as tornadoes and hurricanes. Four areas of community stability are examined including population stability, economic stability, physical services stability, and social services stability to demonstrate policies that can improve resilience to extreme wind events produced by tornadoes and wind-wave-surge loading produced by hurricanes. The cities of Joplin, Missouri and Galveston, Texas, are presented as examples for tornado and hurricane hazards, respectively, highlighting both mitigation and policy approaches to improve resilience and accelerate community recovery. Examples are presented in a free open-source platform known as the Interdependent Networked Community Resilience Modeling Environment (IN-CORE) that is available to anyone as a result of a National Institute of Standards and Technology funded center.

John W. van de Lindt, Ph.D. F. SEI, F. ASCE
Harold H. Short Endowed Chair Professor
Co-Director, Center for Risk-Based Community Resilience Planning
Director, Project IN-CORE
Chief Editor, Journal of Structural Engineering
Colorado State University
Fort Collins, Colorado 80523-1372; USA
Email: jwv@colostate.edu
Bluesky: @commresilience
Web 1: http://resilience.colostate.edu
Web 2: https://www.engr.colostate.edu/~jwv/
Pronouns: he/him/his

Dr. John W. van de Lindt is the Harold H. Short Chaired Professor in the Department of Civil and Environmental Engineering at Colorado State University. Over the last two decades van de Lindt’s research program has focused on performance-based engineering and test bed applications of buildings and other systems for hurricanes, tsunamis, earthquakes, tornadoes and floods. He has led data collection efforts following hurricanes, earthquakes, floods, and tornadoes with the most recent being the December 2021 Midwest tornado outbreak. Professor van de Lindt is the Co-director of the National Institute of Standards and Technology-funded Center of Excellence (COE) for Risk-Based Community Resilience Planning headquartered at Colorado State University in its tenth year. A major portion of the COE is to develop a computational platform IN-CORE to enable communities to measure their resilience to natural hazards. He serves as the Past Chair of the Executive Committee for the American Society of Civil Engineer’s (ASCE) Infrastructure Resilience Division and has published more than 500 technical articles and reports including more than 250 journal publications. He currently serves on a number of journal editorial boards worldwide including as the Editor-in-Chief for the ASCE Journal of Structural Engineering.

The lecture will cover the contributions of Barry Vickery to wind engineering over his career, discussing his work at The University of Sydney, the National Physics Laboratory in the UK (now BMT) and at the University of Western Ontario. His original contributions to wind engineering cover a wide range of topics including bluff body aerodynamics, gust factors, internal pressures, chimneys and vortex shedding, offshore structures, and wind climatology. The talk will follow his career beginning in Sydney, Australia in the early 1960’s and ending at the University of Western Ontario in the mid 2000’s. In addition to his pioneering contributions to wind engineering, he was also a well-respected teacher, and some thoughts and comments from some of his students will also be included.

Dr. Peter Vickery joined Applied Research Associates, Inc. (ARA) in 1988. Prior to joining ARA, Dr. Vickery completed both his Masters and Doctoral studies at the University of Western Ontario. Dr. Vickery has over 40 years of experience in wind engineering. Dr. Vickery retired from ARA in 2022 and is now a part time consultant. Dr. Vickery has published numerous peer reviewed journal papers related to hurricane risk and additional papers related to wind loads on buildings and other structures. He pioneered the development of the probabilistic track modeling approach for hurricane risk assessment, which is now the standard method used for insurance probabilistic hurricane loss modeling. Dr. Vickery was one of the primary developers of FEMA’s Hazus hurricane loss model, which has been in use since 2002 to estimate damage and loss associated with landfalling hurricanes. He has over 20 years’ experience in the application of hurricane modeling relevant to modeling and damage and loss associated with hurricanes and the built environment and its application to insurance loss analysis and rate making. Dr. Vickery has been involved in numerous probabilistic wind risk analyses for nuclear facilities in the US and Canada and has performed numerous hurricane wind-wave analyses for offshore wind farms.

Dr. Vickery is a member National Academy of Engineers and is a fellow of the American Society of Civil Engineers (ASCE) and the ASCE Structural Engineering Institute (SEI). He is a recipient of ASCE’s Collinwood Award, and the Jack E. Cermak Medal.

The identity of coastal communities is tied to their connection to the coast. Increasing climate change-driven coastal hazards (raising sea levels, wind intensification, and compound flooding) together with increased exposure (coastal construction and population growth) is increasing risk along US shorelines. In just the past 3 years, the US has been impacted by four hurricanes that rank in the top ten for US tropical cyclone damages (based on 2024 dollars) as well as numerous fatalities. Increased hurricane intensity is fueled by warmer ocean temperature, and although the number of hurricanes may not increase, Category 4 and 5 cyclones are projected to increase by 10% by 2100. In addition, increased rates of hurricane intensification, slower decay at landfall, slower forward speeds, and increased rainfall are already causing increased impacts. More intense hurricanes produce larger waves and storm surge, greater direct wind damage, and increased erosion, flooding, and infrastructure damage. More rapid intensification results in less predictive accuracy in winds, waves, and surge, and less time for evacuations and storm preparation. Longer hurricane seasons and poleward shifts of hurricane tracks extend the range of impacts in time and space (e.g., 2024 saw the earliest Category 5 hurricane on record in the Atlantic basin, Hurricane Beryl on July 1st). Climate-driven environmental impacts such as coral bleaching and vegetation type/coverage impact natural protection in coastal areas.

Coastal resilience is defined as the capacity to anticipate and plan for disturbances, resist damages and/or absorb impacts, rapidly recover afterwards, and adapt to stressors, changing conditions and constraints. Traditional “gray” coastal engineering approaches (e.g., seawalls, breakwaters, groins) to lower flood and erosion risk can negatively impact the coastal system and disconnect people from coastal amenities. These approaches are also challenging to adapt for nonstationary in the hazard. Nature-based solutions (beach nourishment, reefs, vegetated features) are gaining in popularity and have the potential advantage of natural adaptation, but nature-based solutions require larger footprints to implement and can be ineffective under extreme hazards (e.g., large hurricane waves and storm surge). Hybrid solutions combining hard and soft (gray and green) approaches are an area of active investigation. Nature-based and hybrid solutions also generally have greater environmental and social benefits.

Design and adaption of coastal protection requires quantification of the risk due to wind, waves, and surge over a range of scales. The intersection of wind engineering and coastal engineering has generally had limited overlap. Atmospheric observations and models provide critical input to drive storm surge and wave models that are applied to evaluate coastal risk both through forecasts and hindcasts, but feedback from waves and surge are not commonly applied to the atmospheric models. At the coast, the downscaling of wind information to resolve nearshore processes, wave breaking, and coastal morphological features is challenging. The aeolian transport of sediments on beaches and dunes is dependent on moisture content, armoring, beach gradients, and interaction with beach vegetation on sub-meter resolution. These interactions become even more daunting for the rapidly varying hurricane wind fields in time and space.

This presentation will discuss the evolving coastal hazards and coastal engineering requirements for wind research to quantify and reduce risk for coastal communities.

Smith is a Research Professor at University of Florida and an Emeritus Senior Research Scientist at the US Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory. She earned a PhD from University of Delaware in Civil Engineering with an emphasis in Coastal Engineering. Her research focus is on coastal hydrodynamics, including nearshore waves and currents, shallow-water wave processes, and storm surge. Her projects include theoretical and numerical studies as well laboratory and field experimentation. Smith is a member of the National Academy of Engineering and a Distinguished Member of American Society of Civil Engineers. She received the 2022 International Coastal Engineering Award. Smith serves on editorial boards for Coastal Engineering; Journal of Waterway, Port, Coastal and Ocean Engineering; and Frontiers in Built Environment and is a member of the Marine Board of the National Academies. She has over 200 professional publications.

The performance of cladding, connections, and other building components is critical for reducing losses due to severe storms. From an engineering design perspective, there are two sides to this problem: (1) defining the loads on small elements that depend on complex, sometimes undefined, geometry, and (2) defining the resistance and capacity of these elements, which are often determined by standardized tests that greatly simplify the loading while using set-ups that often neglect possible building system effects. Design wind loads for cladding and building components are typically obtained via the wind tunnel method or from codes and standards, which also rely on wind tunnel data for their development. The determination of design wind loads for these systems is challenging, particularly for systems that are multi-layer and air permeable. Small air gaps between adjacent components and layers cannot be modeled at the typical scales used in boundary layer wind tunnels, which requires relaxation of the usual wind tunnel scaling laws for accuracy. Standardized tests apply uniform, static (or slowly varying cyclic) pressures to find the limiting load. The paper examines recent advances in the understanding of the aerodynamics of such air permeable systems, how the building alters these, and how both of these affect wind tunnel test methods, net loading on the different layers, and the simplifications assumed under standardized tests. Recommendations for developments to ensure improved performance-based design goals and improved disaster resilience of these systems are made.

Gregory Kopp is Professor of Civil & Environmental Engineering at Western University, where he also holds the ImpactWX Chair in Severe Storms Engineering and is the founding Director of the Canadian Severe Storms Laboratory (CSSL). He received a BSc in Mechanical Engineering from the University of Manitoba in 1989, a MEng from McMaster University in 1991 and a PhD in Mechanical Engineering from the University of Toronto in 1995. He has been at Western since 1997. His expertise and research relate to assessing and mitigating damage to structures during extreme wind storms such as tornadoes and hurricanes, building aerodynamics and wind tunnel testing, and wind loading and component testing of cladding systems. He works actively to implement research findings into practice, currently serving as Chair of the ASCE 49 Standards Committee on “Wind Tunnel Testing for Buildings and other Structures”, and as a member of various other building code and design standards committees including the ASCE 7 Wind Loads Sub-Committee. Professor Kopp has won numerous awards including the IAWE Davenport Medal and ASCE’s Cermak Medal.

Extreme winds associated with intense storms such as hurricanes, severe convective storms, and atmospheric rivers pose major hazards to wind energy infrastructure. Storm-resolving models at kilometers resolution are needed to simulate extreme winds and their future changes. Advances in numerical modeling using unstructured grids have made it possible to simulate intense storms at a regional-to-continental scale using regional refinement in global models. While these models have been demonstrated to simulate extreme storms with high fidelity, their high computational cost and low throughput limit their current use to storyline simulations of historic extreme storms and their unfolding in the future. Complementary to storm-resolving models, synthetic hurricane models have been used to support the analysis of storm-induced risk. In this presentation, I will discuss recent advances in storm-resolving modeling and synthetic storm modeling using examples, highlighting successes as well as challenges, and discuss directions in extreme winds modeling to support sustainable wind energy planning.

Dr. L. Ruby Leung is a Battelle Fellow at Pacific Northwest National Laboratory. Her research broadly cuts across multiple areas in modeling and analysis of climate and the hydrological cycle including land-atmosphere interactions, orographic processes, monsoon climate, climate extremes, land surface processes, and aerosol-cloud interactions. Her research on climate change impacts has been featured in Science, Popular Science, Wall Street Journal, National Public Radio, and many major newspapers.

Dr. Leung is the Chief Scientist of Energy Exascale Earth System Model (E3SM) supported by U.S. Department of Energy, a major effort to develop state-of-the-art capabilities for modeling human-Earth system processes on DOE’s next generation high performance computers. She has organized key workshops sponsored by DOE, NSF, NOAA, and NASA, and served on advisory panels and NRC and NASEM committee that define future priorities and opportunities in Digital Twin, AI/ML, climate modeling, hydroclimate, and water cycle research. She is an editor of the American Meteorological Society Journal of Hydrometeorology. Dr. Leung is an elected member of the National Academy of Engineering and Washington State Academy of Sciences. She is a fellow of the American Meteorological Society (AMS), American Association for the Advancement of Science (AAAS), and American Geophysical Union (AGU). She is the recipient of the AMS Hydrologic Sciences Medal in 2022, AGU Global Environmental Change Bert Bolin Award and Lecture in 2019 and the AGU Atmospheric Science Jacob Bjerknes Lecture in 2020. In 2021, Dr. Leung received the U.S. Department of Energy Office of Science Distinguished Scientist Fellow Award. She has published over 500 papers in peer-reviewed journals.

Ahsan Kareem, Dist. FASCE, NAE, is the Robert M. Moran Professor of Engineering in the Department of Civil & Environmental Engineering and Earth Sciences (CEEES) at the University of Notre Dame. He served as the President of the American Association of Wind Engineering (AAWE) and International Association of Wind Engineering (IAWE). The focus of his work is on quantifying load effects caused by various natural hazards on structures and to develop innovative strategies to manage and mitigate their effects. This includes characterization and formulation of dynamic load effects due to wind, waves and earthquakes on tall buildings, long-span bridges, offshore structures and energy related structures that is carried out via fundamental analytical computational methods, and experiments at laboratory, and full-scale. He directs NatHaz Group (NatHaz Modeling Laboratory) which focuses on developments in cyberspace virtual collaborative research platforms, e.g., virtual organizations, IoT, edge computing, crowdsourcing, computational intelligence, living laboratories, sensing and actuation, citizen sensing, web-enabled analysis and design, scientific machine learning (SciML) and cloud-based computing to address challenges posed by natural hazards to the built environment.