Since he was raised in a family of civil engineers, it is not surprising that Ganesh Thiagarajan grew up to become an assistant professor of civil engineering at the University of Missouri-Kansas City. However, not until pursuing his masters degree at the Indian Institute of Technology, Madras (India), did he realize his true place in that world. “Somehow, at that point, I knew I wanted to be in academia,” Thiagarajan recalls. Looking back on his undergraduate classes, he realized the discrepancy between professors who had worked as practicing engineers in industry and those who had not. “There was a big difference in how they presented things, so I decided that if I wanted to be in academia I had to first work as a practitioner,” he says. After spending four years designing offices, residential buildings, and TV antenna towers, and later earning his PhD at Louisiana State University, Thiagarajan now approaches research projects from an academic perspective.
Thiagarajan was recently presented with the National Science Foundation’s prestigious CAREER award for assistant professors. His research, entitled Project FRANCES, aims to explore fracture analysis in concrete via experimentation and simulation. It is especially noteworthy that this five-year award from NSF was the direct result of a prior UMRB research project involving simulation of the response of concrete materials under blast loading.
Presently, as part of a collaborative project with the Missouri Department of Transportation (MoDOT), the Missouri Transportation Institute, and the National University Transportation Center at Rolla, Thiagarajan is working on a project to come up with cost-effective alternative structural solutions for bridge approach slabs on state roadways. Most road paving is made from asphalt; however, when a bridge is built over a waterway or another road, concrete is used instead. An approach slab, typically constructed of reinforced concrete, joins the bridge deck to the pavement and serves as a transition between the relatively soft structure of the pavement and the rigid concrete abutment of the bridge.
As the soil under the pavement and the approach slab naturally begins to settle, the asphalt is pulled down with it, while the concrete is not. This variance in material behavior can cause as much as a few inches of difference in the level of the roadway, resulting in a bumpy ride for the cars and trucks driving over the slab. “Right now MoDOT is interested in finding better designs that will prevent the bump in the bridges,” says Thiagarajan. And there are very sound and sensible reasons for their commitment to a solution. In addition to posing a safety risk, especially to trucks, these bumpy roadways are expensive to maintain because the slabs must be replaced every ten years or so.
Thiagarajan has been investigating several possible structural solutions to this problem. One involves changing the design of the sleeper slabs that rest on the soil and directly support the roadway above it. When trucks and cars approach these slabs and deliver an impact, the sleeper slabs gradually develop cracks and break, contributing to the settling problem. “I’m trying to see if there is another slab that can be used so that the impact is sort of spread out over 25-30 feet,” Thiagarajan explains. Other potential solutions include varying the thickness or length of the slabs. Once a cost-effective alternative is found and implemented across the state, drivers should notice a much smoother ride. “Next time you drive across a bridge, just before you approach the first slab,” he suggests, “see if you feel a difference. Hopefully your car won’t 'take off'. That’s what we hope to avoid.”
Thiagarajan also conducts research and participates in projects in areas that may at first glance seem to fall outside his field of civil engineering. For example, he is working with investigators at the University of Missouri-Kansas City and the University of Kansas to develop digital replicas of human knees, a virtual tool that will hopefully be used in clinical settings to predict the effects of stress on knee joints. By running MRI images of actual patients’ knees through computer software, he and his team have developed an exact replica of the human knee that can be manipulated and studied in a laboratory setting. “It allows you to calculate the stresses in the cartilage, the stresses in the meniscus,” he notes. While computer science and biology are not within his home area of expertise, his involvement in the project has been both instructive and contributory: “I am learning a lot in the process, and we are trying to produce some tools that will be useful in the future.”
Last year, Thiagarajan and a graduate student traveled to China to receive the first place award in an international competition. Sponsored by the Japanese National Institute of Earth Science and Disaster Prevention, and supported by the United States Network of Earthquake Engineering Simulation (NEES), the challenge entailed predicting the effects of an earthquake on a four-story steel building. “The various parameters we had to predict included the accelerations of the floors, the displacements in the floors, drift angles—things that from a designer’s perspective are useful quantities,” he explains. When the four-month competition came to a close, the predictions made by Thiagarajan’s team mirrored the real results of an earthquake most closely, and they won first prize.
In addition, Thiagarajan also offers his skills to the local community, for example by participating in an initiative sponsored by the National Science Foundation (through the ARROWS program) that aims to expose high school students to research in the sciences, including civil engineering. Students spend a week at UMKC, where they participate in modules on different subjects. Thiagarajan, for instance, teaches a unit on earthquakes. “You have to explain the concept of frequencies,” he remarks. “It is amazing how quickly they capture it if you present it in a way that makes sense.” At the end of the module, students construct model buildings, which Thiagarajan then subjects to simulated earthquakes to test the structural strength of their designs.
In this same spirit of community involvement, Thiagarajan is cooperating with the North Kansas City School District to establish a program that would allow students to work for extended periods of time with UMKC professors and graduate students on research relating to blast theory and impact design. While they are still in the development phase, he reports that the group is making strides in trying to identify “a good framework for the students to be exposed to the high end of research, at their level.”