Logo: University of Southern California

Steel Bridge

April 05, 2005 —

Chris Cho, center, and members of the Viterbi School steel bridge team, assemble their masterpiece, a 21-foot long, 220-pound truss bridge.

USC's Viterbi School placed second in this year's AISC (American Institute of Steel Construction) Student Steel Bridge Competition by building a 21-foot-long, 220-pound truss bridge in six and a half minutes.
Six engineering students in the Department of Civil and Environmental Engineering put their steel masterpiece together in record time at the 2005 Pacific Southwest Regional Conference (PSWRC), held April 1 on the California State University, Fullerton campus.  A team from California State University, Long Beach, won first place in the popular bridge-building tournament.
The competition, hosted by the American Society for Civil Engineers (ASCE), brings together approximately 600 engineering undergraduates from 16 universities in California, Arizona, Nevada and Hawaii, for two days of  competition, presentations and networking opportunities.   

“This is a wonderful opportunity for students to share in the practical experience of taking concepts and information taught in their engineering classes and putting it to use,” said Raman Unnikrishnan, dean of the hosting College of Engineering and Computer Science at Cal State Fullerton. “This provides valuable

Joel Waters, who was on the construction team, uses a band saw to sculpt pieces of the bridge.

lessons that can only be achieved when actually taking concepts and knowledge and using them in applications similar to what they will be doing in their careers.” 

The design competition tests the skills of civil engineering students from colleges and universities across the country who are learning the benefits and challenges of using prefabricated steel in bridge construction, said USC’s John Caffrey, a research assistant professor of civil and environmental engineering, who served as the team’s faculty advisor. In addition to the competition, students also have a chance to meet new people, see other schools and apply their design skills.
Serious Business
The students take the competition seriously. For months beforehand, Viterbi School team co-captains Patrick Maguire, a senior civil engineering major, and Chris Cho, a junior civil engineering major, welded, hammered and cut steel strips into small, prefabricated pieces that would be fastened together during competition. Fifteen civil and environmental engineering students worked on the bridge this year, fashioning all of the steel pieces to fit in a box that’s only 3’6” x 6” x 6”.  Although they were allowed to weld and bolt their pieces together in the prefabrication phase, they were only able to connect the pieces with nuts and bolts during the competition.

Co-captain Patrick Maguire welds a section of the truss.

“This year our design was a single span truss bridge that's fairly heavy, but exceedingly strong, and could be built quickly,” said Maguire, who was on last year’s team as well.  “It was heavier than some of the other bridges, but it deflected less than one-tenth of an inch under a load of 2,500 pounds of weight.”

According to the PSWRC rules, students were able to design and scale any type of single span bridge. Single span bridges have only two sets of footings. The competition called for a bridge that would span an imaginary river 21 feet from bank to bank. Students were given a site plan and elevation map of the river valley in which the bridge was to be built.  Maguire’s team picked a truss design that stood about 5-to-6 feet tall and 4 feet wide when it was finished.

“Suspension, truss or beam bridges were all viable options,” Maguire said.  “According to PSWRC rules, the bridge itself was to be a support structure for steel decking, which would simulate a roadway.” 

Amanda Merrick, also on the construction team, uses a drill press during fabrication.


There are four key elements to building a winning bridge, Maguire and his teammates explained.  First, the bridge must be fully pre-fabricated prior to the competition and fit into the specified box.  Second, it must be constructed in as little time as possible using as few people as possible. Third, the bridge must be able to hold 2,500 pounds of weight without bending more than 2 inches under the load.  And last but not least, the bridge must be lightweight.

The Ideal Bridge
"The ideal bridge would be one that is made out of the minimum number of pieces, thus making it very easy and quick to build," Maguire said.  "It would take the entire load without deflecting more than one-tenth of an inch, and would weigh less than 80 pounds, because anything over 80 pounds begins to work against you.  Those were the ideal parameters we were shooting for."
The team worked long hours after classes and on weekends to design and fabricate the 45 pieces that made up the truss. They began in September, during the first week of school, Maguire said, sketching out designs, doing hand calculations, modeling and running computer analyses of their creations to see how well they performed. Caffrey helped troubleshoot various designs with the students.
The spring semester was devoted to fabrication, which included ordering the steel, then cutting it to the required sizes, and finally welding it all together into the pre-fabricated pieces, Maguire said.  Six students were chosen to compete in the regional contest, but they had few chances to test the bridge prior to last week’s competition.  

Seventeen PSWRC steel bridge entries were judged on stiffness, lightness, speed of construction, aesthetics, efficiency and economy. The bridges were  displayed on Thursday, March 31, at the main entrance to California State University, Fullerton. Judging

Chris Cho and Kathryne Ceballos fasten two top pieces together

took place on Friday, April 1, in the Cal State Fullerton Quad.

The first and second place teams from the regional contests will compete in the national competition, to be held May 27-28 at Central Florida University in Orlando.    

For more information about the competition, see http://www.aisc.org/.
--Diane Ainsworth