Volume 13, Number 3, 2005
As soon as John Hillman conceived the idea for a hybrid composite beam to be used in building railroad and highway bridges, he says he knew where to go for advice on how to get started.
The senior associate with the Chicago design and construction firm Teng & Associates turned to UD’s College of Engineering. Specifically, he contacted John W. Gillespie Jr., professor of materials science and civil engineering and director of the Center for Composite Materials, and Dennis Mertz, professor of civil
and environmental engineering. The result has been a partnership that could lead to an innovative type of beam, with the potential to be both longer-lasting and less expensive than those currently used.
“I had met Jack Gillespie and Dennis Mertz back in 1995, working on a composite bridge structure, and I knew that the two of them represented the ideal combination of expertise,” Hillman says.
“Jack directs the world’s largest research organization dedicated to all facets of composite materials, including not only design and analysis but also fabrication and testing, and Dennis is one of the most highly regarded academicians in the bridge community. It was a logical fit.”
Hillman’s design concept incorporated a fiber-reinforced plastic box beam, with compression reinforcement consisting of cement or concrete pumped into a profiled conduit within the beam shell and tension reinforcement consisting of carbon, glass or steel fibers. Now patented under the title “Plasticon-Optimized Composite Beam System,” the beam is a revolutionary new type of structural member for use in bridge construction.
“The construction and rehabilitation of bridge structures in our nation’s infrastructure is a multibillion-dollar industry annually,” Mertz says. “It’s well documented that in addition to new construction, major capital expenditures are necessary to rehabilitate and reconstruct our aging existing infrastructure.
“There’s a tremendous need to develop construction materials that can provide extended service lives to bridge structures, resulting in reduced maintenance and replacement costs in the future. The hybrid-composite beam offers an elegant solution to this objective.”
Hillman teamed with the Center for Composite Materials (CCM) and the Department of Civil and Environmental Engineering and submitted a successful proposal to the High-Speed Rail IDEA (Ideas Deserving Exploratory Analysis) program. Funded by the Transportation Research Board, the program provides seed money for new projects.
The project findings confirmed that the hybrid-composite beam can be manufactured with minimum tooling costs and that the girders can be predictably designed to satisfy the strength and serviceability requirements for railroad and highway bridge structures. Cost metrics indicate that the beam appears to provide a cost-effective alternative to concrete or steel beams, while also offering greater corrosion resistance.
During the second phase of the project, the team members turned their attention to fabrication issues. “This is important because getting a product to market requires that it be producible at low cost,” Hillman says. “With CCM’s expertise in composites manufacturing, we were able to develop a methodology for molding, layup and infusion.”
The researchers say their relationship is a true hands-on collaboration, not a long-distance partnership. Hillman periodically spends several days at the University, working with faculty and research staff in the CCM manufacturing lab and the civil and environmental engineering structure lab. In addition to Mertz and Gillespie, the University team includes CCM research associate Nick Shevchenko, structure lab coordinator Danny Richardson and research technician Gary Wenczel of the Department of Civil and Environmental Engineering.
“The working relationship is great,” Hillman says.
Shevchenko can speak to the challenges involved in fabricating and testing a beam of this size. “Scale is a real issue,” he says. “Things just don’t always scale up the way we think they will. We had fabricated and tested subscale beams, but it’s a big leap to triple the size—three times the size means 27 times the volume because it’s cubic.”
The final objective of the current phase of research involves extensive laboratory testing of a prototype beam, followed by fabricating and deploying a 30-foot prototype bridge on the test facility of the Association of American Railroads in Pueblo, Colo. The ultimate goal of the collaboration is to get the product to market.
—Diane Kukich, AS ’73, ’84M