FEATURE STORY — January/February 2008

Bridging the Gap

For decades, UIC civil engineering professors Farhad Ansari and Mohsen Issa have been researching ways to improve the design, construction, maintenance and safety of the nation’s highway infrastructure

By Richard Asa

Catastrophes have a way of galvanizing the public and private sectors, so it was inevitable after the Interstate 35 bridge collapse in Minneapolis that America’s transportation infrastructure was subjected to intense scrutiny. Engineers at local, state and federal levels scrambled to assure Americans that the nation’s 577,000 bridges would not begin to fail en masse.

Still, if the transportation infrastructure were a student, it would be reluctant to bring its report card home to waiting parents. The influential American Society of Civil Engineers gave the nation’s roads a grade of “D” and its bridges a “C” in the organization’s most recent report card on infrastructure (issued in 2005).

The ASCE 2005 report card also stated that 27.1 percent of all U.S. bridges are “structurally deficient,” and that it would cost $9.4 billion annually over the next 20 years to remedy all their deficiencies. In addition, ASCE estimates that the $59.4 billion being spent on roads annually is “well below the $94 billion needed annually to improve transportation infrastructure conditions nationally.”

Toiling away in UIC’s engineering labs

Whether or not any measures could have been taken to prevent the Minnesota tragedy, the answers will be wrapped in hindsight and ultimately dependent on an ongoing investigation by the National Transportation Safety Board, which is legendary for its painstaking and definitive reports. Meanwhile, engineers in the public and private sectors are loath to speculate, as they seek ways to prevent future tragedies.

For decades, however, UIC’s civil engineering faculty has been seeking ways to improve the design, construction, maintenance and safety of the nation’s civil infrastructure. Their labs, located on the first floor of the Science and Engineering Laboratories Buildings on Halsted Street, are crammed with the tools and materials of their profession: fiber optic sensors, concrete pillars, wire, agate, cement and steel. Powerful computers collect and collate the data compiled when materials are stressed by water, weight, salt, pressure and other simulated road conditions.

Interpreting that data are two of the leading researchers in field, Farhad Ansari PHD ’83 ENG, ’76 UIUC, professor and head of UIC’s Civil Engineering Department, and Mohsen Issa, professor of civil engineering and director of UIC’s Structural and Concrete Research Laboratory. The results of their exhaustive testing, field research and number crunching are relied upon by engineering firms and government agencies alike.

“What [UIC] professors and others are doing is [examining] new technologies, so that when we [civil engineers]... construct or maintain a facility, we build in more resiliency and extend its useful life,” comments David Mongan, ASCE president and president of Whitney, Bailey, Cox & Magnani LLC, an architectural/ engineering/construction firm headquartered in Baltimore. “The solution [to the infrastructure challenge] isn’t just money; it’s innovation in construction techniques, design and materials.”

Using fiber optic sensors
to diagnose bridges

For nearly 20 years, Ansari has been blazing a path for the application of fiber optic sensors to monitor the structural integrity of bridges, tunnels and dams. (Within the civil engineering field, Ansari’s discipline is known as structural health monitoring.)

After completing his doctorate in civil engineering at UIC, Ansari joined the faculty at the New Jersey Institute of Technology. He later returned to UIC to found the College of Engineering’s Smart Sensors and Non-Destructive Testing Laboratory. To date, his research has yielded more than 200 technical articles and garnered more than $12 million in funding from projects, books and patents. For example, one of his U.S. patents covers a system that measures air bubbles in concrete, which is used to analyze the ability of concrete to withstand freeze and thaw cycles.
           
Since 1988, Ansari has received several awards for his teaching, and was recently recognized as the first founding fellow of the International Society for Health Monitoring of Intelligent Infrastructure, a non-profit consortium that promotes information exchange and increases awareness of “smart technology” in the civil engineering community worldwide.

Adapted from their use in aeronautics, fiber optic sensors in infrastructure applications are deployed to gather data to evaluate structural integrity, facilitate maintenance and develop design improvements. Fiber optic sensors offer several advantages over conventional sensors such as accelerometers and strain gauges. They are minute in size, which gives them greater flexibility in terms of placement; can be incorporated easily into complex data sensing networks; and are impervious to electrical and electromagnetic interference (such as cell phones). Fiber optic sensors also are far less prone to fire and explosion, explains Ansari, and relatively affordable. He estimates, for example, that the cost of installing and monitoring sensors for the first five years (at an average-sized bridge) is about $250,000.

Information collected from the sensors, which can be embedded in prefabricated concrete and other materials used to “fast-track” construction, is stored in what he calls an “interrogation unit” attached to a bridge. From there, the information can be downloaded to virtually any computer via satellite for analysis.

The sensors can be used to detect conditions such as cracks and air bubbles, both of which hasten deterioration of concrete. They also can be used to evaluate the quality of concrete mix in real time during pouring, which can help avoid conditions (such as too much water in the mix) that lead to deterioration.

In 2007, Ansari received an Illinois Department of Transportation contract to design a system that can detect scour—the erosion of sediments from underneath piers during the flooding of rivers—at a yet-to-be-determined Chicago-area bridge. Scour is considered the number one culprit in causing instability and eventual catastrophic failure of bridges, says Ansari.

Ansari and his graduate students also have developed sensor systems for a Hudson River bridge in New York and a pedestrian bridge used during the Turin Winter Olympics in 2006. Ansari and UIC have been contracted by the University of Nevada, Reno, to measure post-seismic effects on a reinforced concrete bridge subjected to events that surpass the magnitude of the California Northridge earthquake.

Ansari likens the discipline to a physician’s diagnostic approach, which uses various tests to obtain an integrated and complete picture of a patient’s health in order to provide an accurate health assessment and appropriate treatment. “The more data a doctor has, the better he or she can evaluate a patient,” he says. The same methodology can be applied to roads and bridges. “As we grow older, our physicians need more data,” says Ansari. “It’s the same with a bridge.”

Fiber optic sensor systems have yet to be adapted for widespread construction use, but Ansari and others are creating a groundswell of interest by supplying new data and promising results. “It may not happen in my lifetime, but hopefully before another bridge collapses,” he says.

Concrete under pressure
and promising new materials

Many days, Mohsen Issa is identifiable by his hands alone. Just look for the fingers wrapped in Band-Aids. They symbolize the hands-on approach he takes to his experiments in UIC’s Structural and Concrete Laboratory.

Recently recognized by ASCE for his 25 years in the field, Issa has completed research that has led to advances in theory and practice in the construction of roads and bridges. “His innovative and practical approach to the rehabilitation and replacement of bridge decks is widely used for fast-track construction of highway bridges and has resulted in structures that are safe, effective and economical,” states an October 2007 profile in the ASCE News. “Issa also developed an experimental technology for ascertaining the susceptibility of construction materials to fracturing, a technique that is helping to reduce life-cycle costs.”

Issa states the impact of his approach bluntly: “The goal is to get in, get out—and stay out,” he says with a grin, explaining that when the research and data precede the construction of a road or bridge, the end result is better quality and a longer service life.

The results of his research on fibrous concrete overlays and precast-concrete segments, for example, will be applied in the construction of a new bridge over the Mississippi River, which will connect Missouri and Illinois near St. Louis. Altogether, his funded research has exceeded $4 million (includes in-kind industry support), and has included support from organizations such as the National Science Foundation, Illinois Department of Transportation, Chicago Department of Transportation, Illinois State Toll Highway Authority and U.S. Army Construction Engineering Research Laboratories.

Issa earned his BSCE, MSCE and Ph.D. degrees from the University of Texas, and began his career at UIC in 1989. Through his research funding, he has helped graduate 10 Ph.D. and 13 master’s degree students. Issa was honored with the Harold A. Simon Award for excellence in teaching in 1994 and received the UIC Award for Excellence in Teaching and UIC Teaching Recognition Award in 2000. In 1999, he received the Faculty Research Award from UIC’s College of Engineering and became an ACI fellow. For the past 15 years, Issa also has directed the ASCE student chapter at UIC in constructing a concrete canoe, as part of ASCE’s annual National Concrete Canoe Competition.

“I always work to enhance the existing strengths of the department, as well as to help younger faculty establish new research directions and introduce curriculum changes”—all of which helps heighten the department’s visibility and reputation, says Issa, explaining the synergy between his roles as educator and researcher. “I also understand the current and future needs of the industry, and try to establish and maintain close links with industrial organizations, especially local ones.”

 Consequently, many engineers from both the private and public sectors have visited his structural and concrete research laboratory to witness firsthand just how Issa and his students know what they know. During the last six years, for example, Issa has kept several concrete beams (rehabilitated and strengthened with carbon-fiber reinforced polymers) under simulated road conditions—weight and pressure—while constantly dousing them with water and road salt to test how they will tolerate Chicago’s harsh winters. His experiment has shown that carbon-fiber reinforced concrete “is unbelievably strong,” and that it is “probably three times [stronger] than that of the concrete without it,” he says.

His research also includes developing reliability models for testing new construction materials, such as high-performance cementitious materials. These materials, according to the book, Toward Infrastructure Improvement: An Agenda for Research, have high-strength-to-weight ratios and corrosion resistance, which would allow them to replace conventional materials in bridge construction, as well as increase the load-carrying capacity of bridges. Both materials are remarkably strong, but prohibitively brittle, notes Issa. As a result, he has developed a lab test designed to analyze them for crack growth.

Issa is also known for his experiments with (and analytical studies of) high-performance concrete, a material often used in bridge construction. Here his research focuses on HPC’s ability to withstand severe environments and resist penetration of water and caustic solutions. (The results of his HPC research, for example, were implemented in the Wacker Drive Viaduct Reconstruction Project in Chicago.)

Filling a role vacated by industry

The work being done by researchers such as Ansari and Issa fills an important void, according to ASCE’s Mongan.

“Clearly, we’re in a position to stretch the boundaries on new technology and materials,” says Mongan. “Forty to 50 years ago, companies spent a significant amount of their budgets on research and development, but its magnitude has been reduced to what is probably one-tenth of what it was 30 years ago.