Warren Distinguished Lecture Series

Banners that illustrate CEGE's mission and vision hang in the Charles Fairhurst Rotunda

The Warren Distinguished Lecture Series is made possible by a generous, renewing gift by Alice Warren Gaarden in 1961. Since 1989, we have been bringing in accomplished researchers and speakers from around the world to share their work with students, faculty, and friends of CEGE. Please join us for these lectures!

Upcoming Events

Mar 15  Roman Y Makhnenko, Civil & Environmental Engineering, University of Illinois Urbana-Champaign
Mar 22  Joseph Vantassel, Civil and Environmental Engineering, Virginia Tech
Mar 29  Elowyn Yager, Civil & Environmental Engineering, University of Idaho
Apr   5  Kyle Doudrick, Civil & Environmental Engineering & Earth Sciences, University of Notre Dame
Apr 12  Tim Strathmann, Civil & Environmental Engineering, Colorado School of Mines
Apr 19  Henry Liu, Civil and Environmental Engineering, and Mechanical Engineering, University of Michigan 
Apr 26  Dimitrios Lignos, Resilient Steel Structures Laboratory, École Polytechnique Fédérale de Lausanne (EPFL),  Lausanne (Switzerland)

There are no upcoming events matching your criteria.

Past Warren Lectures

Rethinking America’s Urban Water Infrastructure: Resource Efficiency, Access, and Public Health

Nancy Love
Civil and Environmental Engineering, University of Michigan

ABSTRACT: Water infrastructure renewal is receiving significant attention as many systems are reaching (or exceeding) their design life. Economic prosperity in developed cities is in part due to centralized water systems, which create high levels of water quality and public health. While centralized water infrastructure has served us well, Love argues that we should not be constrained to 20th century thinking as we plan for the future. IT-enabled "smart" hybrid water solutions have the potential to improve efficiency of resource use, enhance equitable access to water services, change consumer and provider behavior around water, and ensure that we sustain a high level of public health even as more people live in close proximity. Love presents case studies from around the globe. One case study explores development of "smart" distributed nutrient recovery systems being tested at the University of Michigan.

(recording not available )

3D Printing of Infrastructure Materials for Terrestrial and Extraterrestrial Constructions: Experiments, Computations, and Future Outlook

Gianluca Cusatis
Civil and Environmental Engineering, Northwestern University

Cusatis answers questions about disruptive force of 3D printing in the construction industry. He discusses recent work in this field performed at Northwestern University, including a presentation of the multiscale 3D printing facility recently established at Northwestern's CEE department. The facility features various 3D printers that are capable of the additive manufacturing of structures with a variety of materials including plastic, cement paste, concrete, and marscrete (a waterless material developed at Northwestern and being used to explore habitat construction using indigenous materials on Mars). Furthermore, Cusatis discusses a novel computational framework for the simulation of fresh concrete. He reviews the formulation, calibration, and validation of the model and demonstrates the application of the formulated model to the simulation of concrete 3D printing.

(recording not available)

The Granular Genome: An Alternative to Constitutive Modeling

José Andrade
Mechanical and Civil Engineering, California Institute of Technology

ABSTRACT: Andrade explores the concept of a granular genome, the set of inherent properties of granular assemblies that, in conjunction with the (external) state, determine the material’s emergent behavior. Andrade argues that this approach can be an effective alternative to orthodox constitutive modeling. Recent results show the remarkable ability of the genome approach in replicating the material behavior well beyond the capabilities of any orthodox constitutive model. One can then explore other portions of the stress space to obtain a thorough picture of the material behavior. Also, evolving granular features such as breakage (extreme morphological changes), degree of saturation (multiple components), and bonding (sintering, ice, etc.) can be quantified, and their impact on the constitutive behavior can be assessed for the first time.

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Rethinking the Seismic Design of Chevron Braced Frames

Jeff Berman
Civil and Environmental Engineering, University of Washington

ABSTRACT: Steel braced frames are widely used as seismic force resisting systems; they provide high stiffness, good ductility, and competitive economy. In chevron or inverted-V configurations, braced frames also allow for architectural flexibility, and architects and structural engineers favored these configurations as recently as the early 1990s. In the late 1990s, updates to seismic design requirements resulted in very large beam sizes for chevron-braced frames, greatly reducing the economy of the system. Recent research has demonstrated that an alternative yield mechanism that relies on flexural yielding of beams in chevron frames provides seismic performance comparable or better than frames designed to current requirements, and the alternative significantly improves the system’s economics. Berman highlights the research that led to discovery of this alternative mechanism, the large-scale experiments and computational studies conducted, and the development of requirements for the system. The new requirements are to be implemented in the next update to AISC's Seismic Provisions for Structural Steel Buildings.

(recording not available)

A Biogeochemical Perspective on the Reactivity of Dissolved Organic Matter in Natural Waters: from Antarctica to the Arctic

Diane McKnight
Civil, Environmental, and Architectural Engineering, University of Colorado Boulder

ABSTRACT: Dissolved organic matter (DOM) is ubiquitous in natural waters; it is derived from degradation of plant and microbial precursor organic materials. DOM concentrations are increasing in lakes and streams of north temperate regions and the Arctic. DOM is of interest to environmental engineers for several reasons. For example, the transport of trace metals and organic pollutants and the production of disinfection by products in drinking water treatment can be controlled by interactions with DOM. Further, environmental engineers, biogeochemists, and aquatic ecologists use similar methods for chemical characterization of DOM even though these research communities address different questions. Diane McKnight discusses how understanding ecological and biogeochemical processes in lakes and streams can provide useful, complementary insights beyond chemical characterization, and lead to managing current environmental engineering issues involving DOM. McKnight presents studies from the McMurdo Dry Valleys in Antarctica, the Okavango Delta in Botswana, and the arctic tundra in Alaska.

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Recent Innovations in Concrete Materials and Technologies

Jan Olek
Civil Engineering, Purdue University

ABSTRACT: The development of cementitious binders capable of hardening by binding of CO2 and recent forays into additive manufacturing (3D printing) of concrete are just two examples of transformations in the ways we think about concrete materials and construction technology. Olek focuses on these relatively young innovations in the traditionally conservative construction sector as a way to address such looming challenges as global climate change due to emissions and need for more sustainable technologies. Olek first reviews reaction mechanisms underlying the formation of cementing phases in low-lime, non-hydraulic binders and highlight selected mechanical and durability properties of concretes produced using such binders. Then Olek explores mechanical properties and fracture behavior of 3D-printed cement-paste elements with two types of nature-inspired internal architectures (“lamellar” and “Bouligand”) as a means to control their microstructure and mechanical response.

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Ultralight Coilable Structures

Sergio Pellegrino
Engineering and Applied Science, California Institute of Technology

Pellegrino and his team are developing ultralight, plate-like, square spacecraft for solar power satellites. Each satellite consists of a central element, four deployable booms supporting diagonal cords, and a series of strips parallel to the sides of the square, connected to four diagonal cords. The strips are ladder-like structures consisting of thin-shell longerons connected by transverse elements, supporting multifunctional “tiles” consisting of photovoltaic and RF elements. This whole assembly can be elastically folded into a star configuration and then tightly coiled around the hub. Proof-of-concept physical models of this structure have been built, and it has been demonstrated that these complex structures fold and deploy in a repeatable way under the action of simple constraints. Future applications of these structures will require upscaling of this structural concept to tens of meters, posing new challenges for the design of thin shell structures.

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Pattern Formation in Suspension Flows

Sungyon Lee
Mechanical Engineering, University of Minnesota

Lee focuses on two complementary flow configurations in which the presence of suspended particles may drastically alter the dynamics of the fluid-fluid interface and lead to pattern formation. First, Lee reports a particle-induced fingering instability when a mixture of particles and viscous oil is injected radially into an air-filled Hele-Shaw cell. Experimental results show that the onset and characteristics of fingering are most directly affected by the particle volume fraction but also depend on the ratio of the particle diameter to gap size. The physical mechanism and reduced model are also discussed. In the second part of the talk, Lee discusses the result of injecting air into a packing of soft hydrogel beads that are saturated in water. This new combination of buoyancy, capillarity, and elasticity under confinement leads to complex morphologies of air migration, as well as nontrivial dynamics in the amount of trapped air in the system.

(recording not available)

An Efficiency Paradox of Uberization

Yu (Marco) Nie
Civil and Environmental Engineering, Northwestern University

ABSTRACT: Uberization promises to transform society based on an intuitive proposition: Advanced peer-to-peer matching guarantees greater overall efficiency. Nie challenges this proposition in uberized ride-hail service through an ananlysis of a service called e-hail. By analyzing hundreds of local markets in Shenzhen, China, Nie discovered e-hail is outperformed &emdahs; in terms of wait time and trip production — by taxis hailed off the street in areas with high densities of passengers and drivers. This paradox arises because a quicker match does not always expedite and enhance a ride-hail service. On the contrary, quick match can induce competition that undermines the network effect, making a passenger less likely to benefit from more drivers, and vice versa, in e-hail service compared to taxi service. Consequently, simply attracting more users may not improve e-hail’s efficiency because its competitive edge diminishes with scale. The finding implies uberization has a limited impact on efficiency and is unlikely to create a “winner-take-all” in transportation.

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Optimization of Lattice-based Models for Simulation of Multi-stage Hydraulic Fracturing

Branko Damjanac
Itasca Consulting Company

ABSTRACT: Treatment of rock mass by fluid injection is a technology used for various objectives by various industries (for example, petroleum, mining, and geothermal). Initially, fluid injection was used by the petroleum industry, as hydraulic fracturing, to increase permeability of oil and gas reservoirs. In the past 10 years, development of multi-stage hydraulic fracturing from horizontal wells was one of the main reasons oil and gas production from shale reservoirs changed the global energy landscape. Damjanac describes a new numerical code based on lattice implementation of the synthetic rock mass (SRM) method, an analytical tool that could be applied for well and stimulation strategy designs and optimization of fractured reservoir treatments by fluid injection. The code can simulate different regimes of hydraulic fracture propagation in naturally fractured reservoirs initiated from multiple perforation clusters and stages. Damjanac describes the formulation of the numerical code including optimizations for different fracture propagation regimes, and he presents results illustrating interactions of hydraulic fractures for typical field conditions.

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