Structural Engineering & Structural Mechanics

Science Friday interviews Abbie Liel on infrastructure resilience

Anonymous — Fri, 25 Feb 2022 22:50:21 +0000

Science Friday interviews Abbie Liel on infrastructure resilience Anonymous (not verified) Fri, 02/25/2022 - 15:50

Professor Abbie Liel was interviewed by Science Friday, a weekly NPR program dedicated to science and technology.

She discusses bridge infrastructure and new ways of building more resilient structures in a segment produced following the recent bridge collapse in Pittsburgh.

Liel's research focuses on ways to make communities safer and more resilient in the face of natural hazards.

Listen to the interview at Science Friday

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Seed grant opens research into future of construction materials, site tools

Anonymous — Mon, 14 Feb 2022 16:15:21 +0000

Seed grant opens research into future of construction materials, site tools Anonymous (not verified) Mon, 02/14/2022 - 09:15

Researchers at CU Boulder are developing an app that could reliably and quickly predict whether batches of concrete made at construction sites are safe. If successful, the work could usher in a new era of building that is faster, more cost effective and safer overall for everyone.

The work is still in its early stages and is funded by a seed grant from the Engineering Education and AI-Augmented Learning Interdisciplinary Research Theme within the College of Engineering and Applied Science.

Assistant Professor Mija Hubler of civil, environmental and architectural engineering said the goal of the project was to develop an app that could collect and analyze sample images of concrete for possible defects using machine learning techniques based on composition, fault lines and visual clues.

“To do that today, we have to send samples to the lab where it is then destroyed to be analyzed – so it isn’t a very efficient process in many ways,” she said. “We are hoping to develop something where you could cut a sample open on site, take a picture and understand how that batch will perform mechanically.”

Hubler said the approach is similar to medical techniques, in which doctors examine images of bones or organs to make assessments with increasingly sophisticated tools and techniques.

However, concrete is a much less homogeneous material, which makes assessment tricky. And users of such an app would need at least some basic education about machine learning to understand the inherent uncertainty in the predictions and how to proceed with them.

“We are talking about – essentially – a smart tool here. These kinds of tools and skills are going to become more common in construction over the next 20 years, especially with the introduction of autonomous vehicles,” she said. “We quickly realized then that it is more of a question of education for everyone on the site. How do we teach these skills? How much does someone need to know about machine learning to use these tools? That is why it fits well with the Engineering Education and AI-Augmented Learning Interdisciplinary Research Theme.”

To address those kinds of questions, Hubler is working with computer science Assistant Teaching Professor Geena Kim. Kim said that while artificial intelligence and machine learning are increasingly common in her field, many other branches of engineering are just starting to use those concepts. She added that the scale and size of data sets in civil engineering make for interesting challenges when creating the needed algorithms, testing with students and understanding the results for broad applications.

“We need to get more data and observations to really understand how people will interact with this app and what their personal experience with AI and machine learning needs to be to use it properly,” she said. “This work will also help with our understanding of these concepts in curriculum and workforce development over time.”

Hubler said the team will continue to refine their approach, while also seeking collaborators at CU Boulder and beyond.

“The primary way we assess and track our infrastructure in America is through visual inspections, so this kind of tool would be quite powerful,” she said.

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What the Marshall Fire can teach us about future climate catastrophes

Anonymous — Tue, 25 Jan 2022 17:17:28 +0000

What the Marshall Fire can teach us about future climate catastrophes Anonymous (not verified) Tue, 01/25/2022 - 10:17

Nearly one month after the Marshall Fire became the most destructive and one of the most unique wildfires in Colorado history, CU Boulder researchers from across campus—many of them personally affected by the fire—have pivoted and applied their expertise to the aftermath, hoping to learn from a tragedy in their own backyard and help prepare the country for the next “climate fire.”

“What makes this fire really unique is that it happened in a community that is full of researchers that study this exact topic,” said Natasha Stavros, director of the Earth Lab Analytics Hub at the Cooperative Institute for Research in Environmental Sciences (CIRES) at CU Boulder. “We are going to have measurements unlike anywhere else.”

What makes this fire really unique is that it happened in a community that is full of researchers that study this exact topic. We are going to have measurements unlike anywhere else.”
–Natasha Stavros

As a grass-fueled December wildfire in a crowded suburb, the fire was quite different than the state’s massive forest fires of 2020, resulting in many novel impacts on the environment and human health. More than a dozen research projects are already underway, investigating everything from its impact on air and water quality, to the fire speeds that drove it, and how changes in infrastructure and insurance could limit damage from future fires like it. Researchers hope the findings can help inform homeowners, local governments and communities today and shape policies for tomorrow.

“In between all of us, there is so much expertise to address the causes and the impacts of this fire,” said Joost de Gouw, CIRES fellow and professor of chemistry. “If we come together to produce and publish research, we can really change the future of how we think about wildfire.”

Recipe for a winter wildfire

Three ingredients contribute to fire on the landscape: fuel, climate and ignition, said Stavros.

Due to higher-than-normal snowpack levels in late winter of 2021, a wet spring and a rainier than normal July, grasses grew abundantly in the Front Range throughout the year. By the time December rolled around, fuel accumulation was up 60% to 70% compared with a normal year. These plentiful dry grasses, combined with a 3-foot snow deficit and fierce Chinook winds, set the perfect stage that day for a spark to spiral out of control.

Avery Hatch, a CU Boulder doctoral student in environmental engineering, monitors indoor air quality in a spared home after the Marshall wildfire. (Photo by Casey A. Cass/CU Boulder)

Environmental engineering faculty Julie Korak and Cresten Mansfeldt collect water samples. (Credit: Fernando Rosario-Ortiz)

This abundant fuel would not have existed without increases in precipitation and snowmelt in the first half of 2021, followed by a drastic lack of moisture in the second half of the year—both of which point to climate as the driving cause.

“It’s the first time in my career I have felt comfortable saying this is a climate fire,” said Stavros.

Climate change will continue to have a hand in the future of wildfire, increasing the length and intensity of fire seasons as well as changing how, when and where water is distributed, said Stavros.

In addition to analyzing the impacts of fuel growth, researchers in the Earth Lab are also examining the role of another major factor in the Marshall Fiire: speed.

The Marshall Fire only burned 6,000 acres, less than half the size of Colorado’s second most destructive fire in state history, the Black Forest Fire. Yet it tore through twice as much infrastructure, accounting for 39% of all homes lost to wildfire disasters in the state since 1999, according to Maxwell Cook, doctoral student in the Department of Geography and the Earth Lab.

The fire also now ranks in the top 15 most destructive wildfire events in the western United States, only one of two grassland fires in that list.

Cook is currently working with Jennifer Balch, director of the Earth Lab, to conduct research on the factors which make a fire most likely to burn down homes.

So far, their data shows speed matters most. This may seem obvious, but Cook, Balch and their colleagues have developed new data that now allows them to track and quantify that impact.

“The speed of the fire is also really what makes it difficult for emergency management personnel to respond, to get evacuation orders out in time,” said Cook. “Management strategies that are aimed at reducing the speed of wildfires could be critically important for communities.”

This could include creating fire/fuel breaks around suburban neighborhoods and removing vegetation next to homes—strategies already broadly in use in foothills communities around Colorado. Early detection systems and quick emergency responses are also key, especially in densely populated neighborhoods.

The Earth Lab is also involved in helping develop better maps of where homes are at risk of wildfire across the West, which can help communities and insurances companies better plan for and mitigate that risk.

“We may need to think hard about what we define as the wildland urban interface (WUI). There's a lot of flammable landscape and development out there that's maybe not accounted for,” said Cook. “Building smarter, both in terms of where we build and how we build, that's going to be a big thing moving forward.”

Clearing the air

Three weeks after the fire, homeowners and renters who did not lose their residences still face an important unknown: Is it safe to go home?

Buildings were inundated with smoke, full of unhealthy compounds created as the blaze burned paint, fried refrigerators and melted metals in nearby homes. These chemicals, absorbed by surviving structures like a sponge, now pose a previously unquantified problem.

Air quality scientists from CU Boulder, CIRES and NOAA quickly compiled an online resource about the impacts of post-fire smoke cleanup in homes. Led by de Gouw, they next installed instruments in several surviving homes to measure levels of harmful gases and understand the lingering effects of smoke on indoor air quality. Another team of scientists have also been driving through affected neighborhoods with a mobile laboratory to measure what the remains of buildings emit into the immediate atmosphere.

An interdisciplinary team including engineers, social scientists and chemists from across campus will continue to collect data indoors over the coming months to inform residents and local governments and learn more about lingering human health concerns that wildfires in urban areas can present.

Downstream effects

Meanwhile, Fernando Rosario-Ortiz and his colleagues are studying water.

For years, the associate dean for faculty advancement at the College of Engineering and his colleagues in the Environmental Engineering Program have worked to understand the implications of wildfire on water. But they usually study forests.

“Combusting homes is a whole different ball game,” said Rosario-Ortiz.

It’s not just wood that’s burning in a suburban fire: It’s homes, vehicles and all the stuff in them: fabric, plastics, electronics, batteries, you name it. Those remains and the compounds created can find their way into local water systems. When a fire is quickly followed by rain or snow, as was the case with the Marshall Fire, concerns about contamination are even higher, he said.

Julie Korak and Cresten Mansfeldt, assistant professors of environmental engineering, have partnered with colleagues across campus, local community organizations and municipalities, to collect surface water samples in the area, test for concerning chemicals and address questions of watershed safety posed by residents. In the next month or so, the team will have initial results to share with stakeholders.

“Everyone here takes their water very seriously,” said Mansfeldt. “This work provides a first fingerprint of how a fire like this impacts a community, and how we can assist recovery.”

Building back better

Now that we know a fire like this is possible, the big question the Front Range faces is: How do we keep this from happening again?

A first step in answering: To get a comprehensive, birds-eye view of the damage.

Read more

Fire resources

To that end, Brad Wham, assistant research professor in the Center for Infrastructure, Energy and Space Testing, will join a national team of colleagues this week to fly drones over the burn sites before cleanup begins, gathering valuable clues about what happened that day. The work is part of a larger collaborative research effort, supported by the Resilient Infrastructure with Sustainability and Equity IRT (RISE) within the College of Engineering and Applied Science, formed in the wake of the fire to connect environmental engineers, social scientists, first responders, and policy experts conducting work on natural disasters.

And once rebuilding begins?

“It is entirely practical to build back better,” said Keith Porter, adjoint professor of civil, architecture and environmental engineering.

Porter explains that using fire resistant materials to build a home doesn’t only make it less likely to burn, but they’re a relatively cheap upgrade (less than $10,000 compared to replacing a home worth $600,000) and due to their longevity, can lead to immense savings over the life of the home.

The International Wildland Urban Interface Code, for example—adopted in parts of Boulder County—requires that fire resistant materials be used in new construction. Porter points out, however, that unless cities and counties mandate this kind of fire code, homebuilders aren’t required to swap wood shingles for a non-combustible roof or to replace vinyl siding with stucco in new developments. When rebuilding, insurance companies may mandate that a house be replaced “like for like,” potentially inhibiting homeowners from replacing flammable building materials with fire resistant ones—even if it could save insurance companies money to let people do so, according to Porter.

As affected residents navigate their insurance policies, find temporary housing in a tight market and try to stay healthy during the omicron surge, fighting for fire resistant materials may not be able to be a top priority. This is why, Porter points out, the real power to protect public safety is not on the individual, but in the hands of local officials.

“Everybody else is affected by somebody else's house burning,” said Porter. “Both in an economic sense and in a moral sense, we really are all in this together.”

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Carbon capture DOE-funded projects may lead to more durable concrete materials

Anonymous — Wed, 25 Aug 2021 22:34:44 +0000

Carbon capture DOE-funded projects may lead to more durable concrete materials Anonymous (not verified) Wed, 08/25/2021 - 16:34

Assistant Professor Mija Hubler and Melvin E. and Virginia M. Clark Professor Al Weimer are collaborating on linked Department of Energy-funded projects to capture and repurpose carbon products from fuel sources into materials for concrete bricks. They hope to reduce pollution while also making stronger, more resilient building materials that require less maintenance and repairs over time.

The collaboration began in 2019, when the researchers received a Research and Innovation Office seed grant for their “Extremely Durable Concrete using Methane Decarbonization Nanofiber Byproducts” project. Based on the results of their initial study, they applied for two separate but related Department of Energy grants the following year.

“Our initial collaboration was motivated by the need to produce a byproduct to financially enable hydrogen for the transportation industry,” Hubler said. “We had previously shown there were benefits of adding solid carbon to concrete. We saw the potential to benefit concrete for infrastructure applications at the same time.”

The DOE approved “Extremely Durable Concrete using Methane Decarbonization Nanofiber Co-products with Hydrogen” through the Office of Energy and Renewable Energy and “Modular Processing of Flare Gas for Carbon Nanoproducts” through the National Energy Technology Laboratory in 2020. The projects’ combined funding totals $4 million.

“Depending on the optimal percent of carbon nano-product being sequestered with addition to cement and concrete, it is possible to replace as much as 25% of the hydrogen used in the U.S. that is made by greenhouse gas-generating steam methane reforming,” Weimer said. “This will have a dramatic impact on reducing CO2 emissions.”

The “Extremely Durable Concrete” project seeks to displace hydrogen production by steam methane reforming with a low-cost and scalable chemical vapor deposition process that produces value-added carbon nano-products. The “Modular Processing of Flare Gas for Carbon Nanoproducts” project will create a modular process to react methane to a value-added carbon nano-product that holds the potential to convert vented or flared natural gas into a commercially viable product.

In both cases, these carbon products can be incorporated into concrete.

“The value-added carbon nano-product ‘sequesters’ carbon from methane as a solid,” Hubler said. “The addition of the carbon nanofiber product to concrete increases the service life of concrete structures. This reduces the need for repair and reconstruction of concrete infrastructure.”

This materials science project is a joint effort between Team Weimer, housed in the Department of Chemical and Biological Engineering, and the Hubler Research Group of the Department of Civil, Environmental and Architectural Engineering.

“The collaboration means we learn a lot about material science research across these fields,” Hubler said. “We have a joint research team of students and postdocs across both projects and departments. Additionally, consultation from our industry partners Forge Nano and National Ready Mix Concrete Association ensures the applicability of our efforts.”

Weimer has been a member of the MSE Program since its founding. Hubler is joining the program this fall.

“Since my research projects entail studies of materials innovation for structural applications, I hope my joining the MSE Program will enable the subset of my students who pursue materials development to take classes directly related to their research and be part of a student cohort of other materials researchers,” Hubler said.

She pointed toward the benefits of materials research for both the natural and built environments.

“Beyond the basic drive for improved cost and performance, structural materials such as concrete are facing a crisis due to their carbon footprint,” she said. “They are the most produced materials in the world and their manufacture has a direct impact on the future climate. As a result, there is a need and urgency to reinvent the structural materials we build with today. The field of new structural materials is exciting and beyond traditional concepts incorporating smart, living, healing and computationally designed materials.”

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Researchers will use DOE grant to help update aging natural gas infrastructure

Anonymous — Wed, 02 Sep 2020 15:43:08 +0000

Researchers will use DOE grant to help update aging natural gas infrastructure Anonymous (not verified) Wed, 09/02/2020 - 09:43

A multi-institutional team that includes three �鶹��Ƶ civil engineering researchers has been awarded $5.4 million from the U.S. Department of Energy to help enhance the performance and longevity of natural gas distribution systems.

Led by Assistant Research Professor Brad Wham, the team will use the award from the DOE’s Advanced Research Projects Agency-Energy (ARPA-E) to develop a new testing and modeling framework to allow the gas industry to better evaluate the products it uses to rehabilitate aging cast iron and steel natural gas pipelines.

The award is part of ARPA-E’s Rapid Encapsulation of Pipelines Avoiding Intensive Replacement (REPAIR) program. REPAIR aims to develop technologies to reduce natural gas leaks from legacy and outdated natural gas pipes by creating a suite of technologies to enable the automated construction of new pipe inside existing pipe.

“Our objective is to validate a 50-year design life for innovative pipe-in-pipe systems by developing numerical, analytical and physical testing protocols,” said Wham, who serves as managing director of the Center for Infrastructure, Energy and Space Testing (CIEST) facilities at CU Boulder.

His partners on the project will be center co-directors Mija Hubler and Shideh Dashti, as well as researchers from Cornell University, the University of Southern Queensland and the Gas Technology Institute.

Wham added that the project will focus on pinpointing when pipes are likely to fail and establishing performance criteria for replacement pipes.

“CIEST is perfectly positioned to take on this kind of critical infrastructure research,” Wham said. “We not only have the facilities and faculty expertise for large-scale structural and materials testing, but also the industry experience necessary to provide relevant, real-world recommendations that can be rapidly accepted into practice.”

Led by Assistant Research Professor Brad Wham, the team will use the award to develop a new testing and modeling framework to allow the gas industry to better evaluate the products it uses to rehabilitate aging cast iron and steel natural gas pipelines.

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CEAE Professor Abbie Liel Awarded ASCE SEI Fellowship

Anonymous — Tue, 11 Dec 2018 17:19:50 +0000

CEAE Professor Abbie Liel Awarded ASCE SEI Fellowship Anonymous (not verified) Tue, 12/11/2018 - 10:19

Dr. Abbie Liel of CU Boulder’s Department of Civil, Environmental and Architectural Engineering will advance to the title of Fellow within the American Society of Civil Engineers Structural Engineering Institute (SEI) at the annual Structures Congress in April 2019. This title honors Dr. Liel as a leader and mentor in the profession of structural engineering. Dr. Liel is well known for her contributions to structural engineering education and research on extreme loading, such as that due to earthquakes and snow.

The SEI is committed to improving the field of structural engineering by reinforcing the relationship between academic research and the engineering industry. At the annual Structures Congress, over 1200 structural engineers meet to discuss and exhibit innovations in the industry. Dr. Liel and the other new Fellows will be honored at this event. Dr. Liel will become our department’s only current SEI Fellow.

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DOE Grant to Increase Safety of Nuclear Waste Storage

Anonymous — Fri, 16 Nov 2018 21:02:49 +0000

DOE Grant to Increase Safety of Nuclear Waste Storage Anonymous (not verified) Fri, 11/16/2018 - 14:02

Professors Yida Zhang and Yunping Xi from the Civil, Environmental and Architectural Engineering Department at the University of Colorado Boulder were awarded $789,000 from the Department of Energy for their research project “Time-Dependent THMC Properties and Microstructural Evolution of Damage Rocks in Excavation Damage Zone.” This research will contribute to increasing the safety of nuclear waste storage.

"Since the closure of the Yucca Mountain project, U.S. has been reevaluating all the options available for geological disposal of high-level nuclear wastes. This research will help accelerate this goal by evaluating the suitability of salt rock and claystone formations for long-term isolation of nuclear wastes,” said Zhang.

Nuclear energy is an efficient and greenhouse gas free method of electricity generation with one major issue: the waste from nuclear power plants is radioactive and potentially harmful. The current consensus is that the best potential solution for this high-level nuclear waste (HLW) is deep geological disposal.This would involve building a large repository deep underground in bedrock or inside a salt dome. This would allow the isolation of the nuclear waste until it is no longer hazardous. The U.S. Nuclear Regulatory Commission (NRC) requires that nuclear waste is isolated for 1 million years. Due to the massive time scale involved, engineers need to be very confident that their deep geological disposal repositories are stable and isolated from the outside environment. Due to the challenges in developing these repositories, none are currently in operation despite 50 years of research in multiple countries. For engineers to better control the uncertainties associated with million-year time scale, they need to improve their understanding of the coupled thermal-hydrological-mechanical-chemical (THCM) processes in relation to the evolving microstructures of the host rocks.

Figure 1: Left, schematic of excavation damage zone; right, the increase of permeability near the excavation.

The stress state of host rocks are deeply perturbed by the construction of an underground opening, creating a region known as the excavation damage zone (EDZ). EDZ’s include increased fracturing and fissuring parallel to the opening face of the rock. These cracks and holes can allow groundwater to flow into the repositories.The EDZ is dynamic and variable. It’s time dependent behavior is poorly understood, especially in a long-term sense. Zhang and Xi will try to obtain a better understanding of the

Figure 2: Excavation damage zone

behavior of the EDZ as a function of post-closure time.

“We will use coupled thermo-hydro-mechanical tests to probe the creep behavior of these rocks in laboratory time scale (e.g. one month), then extrapolate the results to geological time scale (e.g. one million years) via multi-scale theoretical and numerical models to be developed in this project,” said Zhang.

Zhang is the lead PI of this project. His research with CU focuses on geotechnical engineering, including constitutive modeling of geomaterials interacting with environmental factors and micromechanics of granular materials. Xi focuses on structural engineering and materials science, including evaluation of nuclear power plants and containment structures. They are using their background in micromechanics of particles to gain a better understanding of the long term effects of deep excavation.

“We are extremely excited to get this project, to help shape the future of U.S. energy solutions and meanwhile minimize environmental impacts.”

Zhang and Xi will use their background in geomechanics to analyze EDZ behavior in salt and argalite, two materials with promising potential for deep geological disposal. While there are many other aspects involved with the behavior of EDZs, their research will help make nuclear energy a more safe and reliable option.

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Civil engineering researcher tapped for nuclear war study

Anonymous — Wed, 02 Aug 2017 19:15:45 +0000

Civil engineering researcher tapped for nuclear war study Anonymous (not verified) Wed, 08/02/2017 - 13:15

When a nuclear bomb goes off, it starts a chain of events whose effects reach far beyond the blast site. Over the next three years, Professor Yunping Xi of civil, environmental and architectural engineering will be involved in a study to quantify those effects in the event of a nuclear war.

The study brings together a diverse group of researchers, led by CU Boulder Professor Brian Toon and Rutgers University Professor Alan Robock, who were part of the first studies that formulated the “nuclear winter” theory in the early 1980s.

Each researcher will look at a link in the chain of events set into motion by a nuclear conflict, Xi explained. For instance, a group of nuclear weapon experts will begin by developing potential nuclear war scenarios, in which numbers of weapons and targets will be determined.

Then, Xi and his team will examine what happens if a bomb hits a large metropolitan area, burning everything from buildings and bridges, to the contents of trash collection sites.

“The temperature at the blast center is very high. Buildings will burn, along with all of their contents – furniture, books and flammable construction materials,” he explained.

Xi said they will start with data collected by other organizations on construction materials used in structures and infrastructures in major cities. Then, they’ll integrate research he’s done previously on how those materials react to high temperatures, and then determine the amount of elemental carbons and other chemicals generated from a targeted city.

Their goal is to help determine how much soot will be released into the atmosphere in each selected nuclear war scenarios. From there, other teams at The Laboratory for Atmospheric and Space Physics (LASP), National Center for Atmospheric Research (NCAR) and Rutgers University will study how that soot moves and spreads, and how it affects climate, agriculture, food supply and much more.

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