University of Wisconsin Madison: The Art of Bridge Building
In roughly four minutes, the UW-Madison Steel Bridge Team can construct an 18-foot-long bridge that easily holds 2,500 pounds.
That lightning-fast time is the product of hundreds of hours of preparation and hard work by a group that, for more than a decade, has been a regular National Student Steel Bridge Competition regional winner and national championship contender.
2005-06 Steel Bridge Team
The steel bridge competition challenges university teams around the country to design, fabricate, test and build a steel bridge within certain spatial and structural constraints. Teams strive to earn the lowest overall score based on their performance in six categories: bridge appearance and poster display, construction speed and time penalties, construction economy, lightness, stiffness, and structural efficiency.
For the 2007 competition, a fictitious state department of transportation is seeking to replace a century-old bridge that spans a river and adjacent floodway. Each team must design a 1:10 scale model and erect it under simulated field conditions to demonstrate its concept. At that scale, the river width is 9 feet; the bridge may be up to 4 feet wide and span between 18 and 20 feet.
Constructing the bridge during competition (Large image) |
Among the restrictions: A single component, or “member,” can weigh no more than 20 pounds and may be no larger than 3 feet long by 6 inches square. During assembly, each member must connect directly to every member it touches by at least one steel bolt and hexagonal nut combination.
Construction takes place in a 95-by-15-foot area, including a 15-foot-square staging area on either end. The construction team, which can include up to six builders and one superintendent, may not cross the river while building the bridge.
The competition is fierce and the margin of error is very small. At the 2003 national competition, for example, the team placed in the top three in five of the six categories, yet missed a first-place finish by two seconds of construction time. In 2006, bridge deflection was greater than the group expected, yet the team scored well in other categories and took home a third-place finish—its second-best showing in the national competition since the event began in 1992.
Naturally, the team is excited about its design for the 2007 competition— particularly since it incorporates the fewest number of components possible. “It performs fairly similar to other ones with a lot more members,” says current team co-chair Adam Bechle, a civil and environmental engineering junior. “We picked this one because there wasn’t a huge difference in the structural stability.”
To simulate loads, weight and deflection, team members analyze the bridge using a computer program called SAP 2000. “We have hundreds of thousands of lines of data that it prints, and we figure out where we need to pull that data so that we can figure out the deflections we need,” he says.
While a civil engineering background is helpful for members hoping to shape the bridge design, the Steel Bridge Team is open to anyone, says Bechle. Team members learn how to operate machine-shop tools and fabricate small bridge parts, including connectors like sleeves, pins or dovetails. Per a broad interpretation of competition rules, such innovations circumvent the need for a time-consuming bolt-and-nut combination.
During the university winter break, about 10 students put in 12-hour days at Endres Manufacturing in Waunakee. The company purchases materials for the team and “loans” them an experienced welder and its machining facilities for a week. “We don’t know how we would fabricate the bridge if it weren’t for them,” says Bechle.
Once the bridge is finished, the “athletes” take over. Working initially for three or four hours on Saturday afternoons in the Engineering Centers Building, the construction crew choreographs the most efficient way to assemble the bridge. “We put painter’s tape on the floor and set up the yard exactly like it says in the rules,” says Bechle.
The crew first walks through the assembly, noting restrictions in the rules about how many people can be in the construction area at a time, where they can and cannot step, and how they can handle and place bridge members. By the time the builders have run through the assembly several times, they sprint into and out of the construction area like dancers in a wild musical production. Before the competition, these students will have assembled and disassembled their bridge more than 100 times.
In practice as well as in competition, their focus is unwavering and the intensity is high. It truly is a sport—and one that combines creativity, ingenuity and mental and physical agility, says Bechle. “You can win a national championship, whereas in high school sports, you can win a conference championship, or something like that,” he says. “Here, you’re competing against the best people in the nation.”
Bechle joined the team as a freshman and says a benefit of membership is that it has provided him a way to apply his engineering knowledge outside the classroom. The team’s culture of mentorship gave him an opportunity to learn from and now, to teach, his fellow students. In addition, he says, employers appreciate his leadership role. “If you’re looking for an engineering job, you’re going to be solving problems and working in teams,” he says. “You know—it’s exactly what you do here.”
