Concrete check-up: Fae Azhari develops diagnostics for critical infrastructure

Professor Fae Azhari (MIE, CivE) holds a sample of the self-sensing concrete she designed. Her work helps monitor the structural health of crucial infrastructure such as bridges, roads and hydroelectric dams. (Credit: Roberta Baker)

This story originally appeared on U of T Engineering News.

Canada will spend $125 billion on infrastructure maintenance and expansion in the next 10 years. Professor Fae Azhari (MIE, CivE) is helping stretch those dollars farther by keeping our buildings, bridges, roads and reservoirs safe and structurally sound for longer.

Azhari’s research focuses on structural health monitoring. Just as you visit the doctor for periodic check-ups, structures need their health checked too — but instead of blood tests and heart rate measurements, engineers usually perform visual inspections and spot-checks with sensors and instruments.

“The problem with visual inspections is that they’re pretty subjective, and with periodic monitoring, you can miss certain events or failures,” says Azhari. “Now we’re moving toward continuous monitoring by incorporating permanent sensors on important structures to get real-time data.”

Degradation or damage suffered between inspections can have catastrophic consequences. In June 2013, a rail bridge just outside of downtown Calgary partially collapsed as a train was passing over it. The train, carrying flammable and toxic liquids, derailed. Emergency measures were taken to prevent the railcars from falling into the Bow River, which was running high with summer floodwater. The Transportation Safety Board of Canada determined that floodwaters had eroded the soil around the bridge’s foundations, causing the collapse. This loss of sediment from around foundational supports is called scour.

“Believe it or not, this happens very often, especially in North America and some Asian countries,” says Azhari. “Scour is a huge problem.”

For her PhD research at the University of California, Davis, Azhari tackled scour from a new angle: she took commercially available sensors that measure dissolved oxygen, typically used for agriculture or biological applications, and used them for sensing scour. Azhari’s design was to attach a number of oxygen sensors at increasing depths along the buried length of the bridge pier. If the pier is properly buried, the dissolved oxygen levels detected by the sensors should be very low — but as scour erodes the sediments and exposes the sensors to flowing water, the dissolved oxygen levels rise. As scour progresses, more and more sensors become exposed, indicating how badly scour is threatening the bridge’s structural integrity.

She has also worked on concrete sensors, including a design that integrates conductive carbon fibers and nanotubes into concrete, making it a self-sensing material. Measuring the resistance across the material reveals the stresses and strains on it. “This technology is well-proven in the laboratory, but moving it to the field is a big challenge,” says Azhari.

As she builds her research enterprise, Azhari plans to collaborate across disciplines and with key partners who could benefit from her sensors, as well her analysis and insight into the data that comes from them. “Transportation infrastructure, utilities, dams, power plants, wind turbines — basically any engineering system — needs maintenance and monitoring,” she says.

“It’s very important to get these sensors from prototype to implementation, and I want to work on that.”

Clean air map from U of T Engineering researchers helps cyclists avoid air pollution

Civil engineering post-doctoral researcher Sabreena Anowar and Professor Marianne Hatzopoulou (CivE) are studying the risks of air pollution on cyclists and their impact on route choice. (Photo: Tyler Irving)
Civil engineering post-doctoral researcher Sabreena Anowar and Professor Marianne Hatzopoulou (CivE) are studying the risks of air pollution on cyclists and their impact on route choice. (Photo: Tyler Irving)

Civil engineering post-doctoral researcher Sabreena Anowar and Professor Marianne Hatzopoulou (CivE) are studying the risks of air pollution on cyclists and their impact on route choice. (Photo: Tyler Irving)

This story originally appeared on U of T News.

Cyclists face a difficult dilemma: on one hand, cycling is good for your health and the environment; on the other, cyclists are more exposed to risks such as accidents and air pollution. New research from U of T Engineering is helping cyclists map cleaner routes to minimize this exposure.

“In general, the benefits of cycling certainly outweigh the risks,” says Professor Marianne Hatzopoulou (CivE). “If you are a healthy person, you are better off to continue cycling than stop.” Nevertheless, when it comes to air pollution, cyclists are at a disadvantage.

“Studies have shown that the concentration of air pollutants tends to be higher inside vehicles than outside them,” says Hatzopoulou. “However, cyclists have a higher breathing rate, which means that they inhale more of these pollutants, and they go deeper into the lungs.”

Such pollutants include ultra-fine particles, as well as nitrogen oxides. Hatzopoulou cites studies associating increased exposure to these pollutants with respiratory problems and certain types of cancer. Her own research has shown that they can even have immediate, measurable effects on the cardiovascular system.

To help address this challenge, Hatzopoulou has created a tool called the Clean Ride Mapper for both Toronto and Montreal. It is essentially a Google Map with an extra layer representing the average concentration of pollutants in a given area, as measured by her team and collaborators. Using this data, algorithms can be constructed to work out not only the shortest route between two points, but also the one that exposes the cyclist to the lowest levels of air pollution.

Hatzopoulou and Anowar outfit a bicycle with equipment to detect the concentration of pollutant particles in the nearby air. (Photo: Tyler Irving)

Hatzopoulou and Anowar outfit a bicycle with equipment to detect the concentration of pollutant particles in the nearby air. (Photo: Tyler Irving)

Hatzopoulou intends to further refine the maps — for example, by incorporating real-time pollution concentrations instead of static data — but lately she has been pondering another question: are such tools actually useful to cyclists?

“There are a lot of factors that influence the choice of a cycling route besides pollution,” she says. “For example, there is safety, separation from traffic, elevation, distance, etc. Which ones would cyclists be willing to trade off in order to decrease their pollution exposure?”

Sabreena Anowar (CivE), a post-doctoral researcher on Hatzopoulou’s team, is working on an answer. She’s designed a survey that proposes several different cycling routes and asks cyclists to choose which one they would prefer.

“No route is perfect,” says Anowar. “They all vary in terms of traffic volume, pollution, elevation, travel time and other attributes.” By measuring which routes people would choose for either a recreational ride or a commuting ride, Anowar and Hatzopoulou hope to better understand how cyclists factor the risks of pollution into their activities. This in turn can help improve the design of tools like the interactive maps.

The survey was launched in Toronto, Montreal, Orlando, Austin, New York in collaboration with researchers in those cities. It will be open at least until June, and Anowar and Hatzopoulou are hoping to get at least 3,000 participants. In addition to their own research, Anowar says that the data could also be useful for city planners. “It will help identify how people value road infrastructure like separated lanes or signage,” says Anowar. “If we build more infrastructure like this, perhaps we can encourage people to cycle more.”

To help Hatzopoulou and Anowar in their research, complete the online survey for either a recreational ride or a commuting ride.