For the fifth consecutive year, I happily attended the ASCE/AISC National Student Steel Bridge Competition (NSSBC)—this year hosted by University of Washington, in Seattle on May 31st - June 1st, 2013. This competition poses a directly applied challenge to students’ skills in steel design, fabrication, scheduling, and management. Year after year, students agree that this competition is equal parts hard work, hands-on learning, and fun!
Bentley was proud to continue as a National sponsor; we also (again) provided free software and tutorials to all participating steel bridge teams in ASCE student chapters as they began work on their 2013 designs last fall. (See my sponsorship blog).
The rules of the Student Steel Bridge Competition change annually, simulating a request for proposal and resulting in a 1:10 scaled model to demonstrate the merits of the design. This year’s problem statement involved a request for design/build proposals for a bridge providing direct access from the suburbs across the river, since revitalization of a waterfront area resulted in vehicle traffic exceeding city street capacity. Mandates included accelerated bridge construction (to minimize travel and economic disruptions), clearance for tour boats, and a cantilever over a historic billiard parlor.
210 teams from the United States, Canada and Mexico competed in the regional ASCE Student Conferences; 49 of those teams qualified for the 22nd annual National finals.
Friday May 31st found the qualifying teams in UW’s Red Square for registration, bridge set up and display judging. This first day provided the teams with ample time to interact—and to scrutinize the work of their competitors!
First, between 3 and 6 team members gathered at the build stations, carefully placing each tool and every individual component of their bridges in the staging area. The goal is to have the fastest build time and lowest building cost, so strategy is important. While more team members increase construction speed, they also add onto construction costs. Under the watchful eyes of the judges, the builders raced the clock while attempting to avoid any penalties. One piece at a time, students ran each component of their bridge over to the builders, who scrambled to construct their bridge as quickly as possible.
This year, the fastest time was 4:07, by University of California, Davis
After the judges evaluated the construction, deemed it sound, and recorded the official time (adding any penalties), each team moved their bridge to the Load Testing station. First, the students applied a standardized lateral load test. Decking was placed at the center of the back span and then 75 lbs were added; a 50 lbs lateral pull was applied, and the sway must not exceed 1/2 inch. Next the lateral load test of the cantilever was conducted in the same manner; again, the sway must not exceed ½ inch.
Once both lateral load tests were passed, the loads and decking were removed and the vertical load tests began. Two sections of decking were added, and three targets measured vertical deflection. 100 lbs preload were added to the decking on the back span, and 50 lbs preload were added on the cantilever. An additional 1,400 lbs then were applied to the back span, where sway cannot exceed ½ inch. Finally, 950 lbs were added to the cantilever—for a total load of 2,500 lbs on the bridge. Sway cannot exceed 1/2 inch, and deflection cannot be more than 2 inches on the cantilever or 3 inches downward on the back span.
Each bridge is ultimately judged on the following categories: display, construction speed, lightness (lowest total weight), stiffness (lowest aggregate deflection), construction economy (lowest construction cost), and structural efficiency.
And this year’s winners are....
1st place: University of California, Berkeley
2nd place: Massachusetts Institute of Technology
3rd place: University of California, Davis.
Congratulations to all of the participating teams, for jobs well done!
You can read more about this competition at http://www.aisc.org/steelbridge, and see full results here: http://www.nssbc.info/History/2013NSSCResults.pdf