Videoconferencing supports student design

In upcoming years, the majority of bridges across the country needing rehabilitation or replacement will be short- to medium-span length bridges. Precast, prestressed concrete beams and girders can be a cost-competitive alternative for rehabilitation at these span lengths. Clarkson University, Potsdam, N.Y., is addressing this trend in the bridge industry by introducing its graduate students to prestressed concrete design.

Six students — two Master of Engineering and three Master of Science candidates, along with one senior undergraduate — had the chance to design a bridge by way of an innovative semester long program.

Senior-level undergraduate students worked on a highway steel bridge comprehensive design, as part of the university’s capstone design course, and the graduate students designed a structural alternative to the steel using prestressed concrete.

To facilitate the prestressed concrete bridge design project, the Environmental Engineering Department called on both the consulting engineering community and the manufacturing industry. This partnership forgoes the traditional classroom approach in favor of something a little more innovative — “real-time” consultation through a weekly two-hour video teleconference coordinated by the University’s Education Resource Center and ATT in Syracuse, N.Y. It marks the first time that video teleconferencing technology has been used to teach a course at Clarkson.

The design project was taken from an actual “real-world” project originally designed by the New York State Department of Transportation’s (NYSDOT) Region 7 Bridge Design Group and currently under construction.

The existing 1929 steel truss bridge located on Route 56 over Hannawa Falls/Racquette River in Colton, N.Y., is being replaced with a two-span, 240-foot continuous-span steel composite plate girder superstructure.

The senior-level capstone design course duplicated the steel plate girder superstructure design.

However, the graduate students designed an alternative using three 80-foot simple spans of prestressed concrete multi-box beams. The superstructure can carry two 12-foot traffic lanes and 8-foot sidewalks on both sides for a total out-to-out width of 40 feet. It included 10 4-foot-wide and 39-inch-deep prestressed box beams with a 6-inch concrete wearing surface, concrete sidewalks and four-rail bridge rail. An HS25 truck was the design-life vehicle.

During each weekly session, Steven Skeele, of Syracuse-based C&S Engineers who helps lead the interactive sessions, presented an element of the design methodology by duplicating the students’ project, but substituting American Association of State Highway and Transportation Officials (AASHTO) prestressed I-girders and a reinforced concrete deck.

When the sessions were completed, the students submited a prestressed concrete box beam bridge design that included design calculations performed with Mathcad or Maple software, superstructure plans and section details, design load and camber tables and other miscellaneous superstructure component details.

Final grades were based on the written design report and an oral presentation of the project.

Toward the end of the semester, the students went on a field trip to the Spancrete Northeast’s manufacturing plant in Manchester, N.Y., to get a first-hand look at the manufacturing process involved in producing prestressed concrete beams. The company also gave the students PC-based computer prestressed concrete design software to help them check their manually designed projects.

The bridge design pilot course helped provide young engineers with an excellent opportunity to focus on and solve a real-world problem while also introducing them to the newest technology and equipment in teleconferencing. In this case, videoconferencing made possible the timely and direct interaction between a rurally located university and more urban-based businesses and industry.

Other benefits are immediate. The students’ hands-on experience with prestressed concrete design adds a new dimension to their education, development and career marketability.