By Denise Brehm
Civil & Environmental Engineering

The regionally top-ranked MIT Steel Bridge Team placed sixth at the national competition at Purdue University May 29, an extraordinary feat for this young team of undergraduates in its fourth year of participation. MIT ranked first among private universities.

Participants in the competition were required to design a 21-foot bridge that can be assembled quickly (the top speed this year was 3 minutes, 12 seconds) and withstand loads of 2,500 pounds with little deflection or sag. While the design rules change annually, all bridge pieces must fit into small boxes (about 3.5 feet long), and during construction, each team member is allowed to enter only certain portions of the staging area and to hold only one bridge piece at a time. This requires team members to pass pieces from hand to hand, relay-race style, as they construct the bridge.

The students’ success this year is due largely to their enthusiasm, willingness to put in late nights and their ability to work well under deadline pressure. Another very important factor was their bridge design, which benefitted from the work of Pierre Ghisbain, a graduate student advisor to the team whose area of research is earthquake engineering and structural optimization. The Department of Civil and Environmental Engineering (CEE) awarded Ghisbain the Trond Kaalstad (Class of 1957) Fellowship for his voluntary efforts working with the team.

“My specialty is optimization, and the whole competition is really about optimization, so I decided to jump in,” said Ghisbain, who had no prior experience in bridge design, but was very familiar with engineering design software.

“Without his guidance on design issues and the many hours he devoted towards fabricating the bridge during evenings and weekends, the student team would not have been as successful,” said the team’s faculty advisor, Professor Jerome Connor of CEE.

Building a better bridge

Ghisbain explained that the team chose a unique design concept, a truss structure that had far fewer pieces and less depth (the measurement of the height of the horizontal “beam” of the bridge) than the truss structure traditionally seen at the competition. This design emphasized tight connections to optimize stiffness, the category in which the team placed third, and less material to optimize efficiency.

Bridges are judged on five aspects that go into an overall ranking. A sixth category, “aesthetics,” is used as a tiebreaker. The “economy” rating is based on the construction time and the number of builders. “Efficiency” is based on weight of the bridge and deflection. “The MIT team has always done well on speed [6:33 this year], and economy. This year’s big jump is due to much better stiffness and efficiency scores,” said Ghisbain.

“At the awards ceremony, we weren’t ready when they called ‘Massachusetts Institute of Technology’ for third place in the stiffness category,” said co-captain Emily Moberg, a junior majoring in environmental engineering science who blogged about the team this spring. “This critical win, against many heavier, deeper bridges, helped us to place sixth in the overall competition. The team was ecstatic to have finally broken into the top 10!”

Facing stiff competition

Many of the 197 teams that participated in regional competitions earlier this spring come from universities with very large civil engineering departments that have participated in the competition for many years. For instance, the 2010 national champion, North Dakota State University, has four previous No. 1 rankings since 1995, and 438 undergraduates in its Department of Civil Engineering and Construction. No. 2 ranked University of California at Berkeley has more than 400 undergraduate students in its Department of Civil and Environmental Engineering.

By contrast, MIT CEE has about 100 undergraduate students. The Steel Bridge Team is made up of nine undergraduates with two graduate student advisors and one faculty advisor. CEE lab instructor Stephen Rudolph provides many hours of hands-on shop assistance to the team, and two industry volunteers — Jimmy Duffy and Jimmy O’Donnell of Boston Bridge Services (fondly referred to as “the two Jimmies”) — help the team with welding.

“The big universities have very large teams of undergraduates — 20, 30 even 40 — and many faculty are involved,” said Ghisbain. “The small schools have mostly graduate students and they’re all guys. Our team is small, very young and female. So we are very different from the other teams.”

Nevertheless, the team has made it to the national competition in each of its four years, placing 24th in 2007, 21st in 2008 and 18th in 2009. In both 2009 and 2010, the team was regional champion.

The 2010 MIT Steel Bridge Team members are seniors Dan Jimenez, Jana Marjanovic, Matt Pires, Gina Policelli and Adam Talsma; juniors Kim Huppert, Alex Jordan and Moberg, and freshman Scott Landers. Graduate student Tina Lai, who was a team member for three years as an undergraduate and once clarified the rules for the judges during a competition, served as a graduate student advisor. This was the 18th year of the competition, which is sponsored by the American Society of Civil Engineers and the American Institute of Steel Construction.