This past weekend was the 2016 AISC Steel Bridge Competition. Lehigh is part of the Mid-Atlantic Region (MAR) and this year Drexel University hosted the event. For the past several months the team has been designing, training, and building our bridge for competition and we finally got to see it tested on Sunday.
Saturday is the first day of the competition which involves a judges review of each bridge, along with an essay presentation required by each team, and other meetings as well. This year the topic of the essay was about international ethics, in which Lehigh did very well. Sunday is the main event, bridges are built under a time limit and are then load tested with thousands of pounds. The actual event took place across the Delaware river in Cherry Hill, NJ at the Camden County Boat House. Overall the team showed improvement this year as it was the first time in recent history the team was not disqualified. In previous years the team has been disqualified for different reasons like exceeding the build time limit and failing the lateral load test.
This year we just barely built the bridge in time at around 42 minutes of the allowable 45 minutes. The overall design was similar to last year with a few tweaks made to the arch, cross bars, and connections. These tweaks helped us to reduce build time by a lot since last year it took about an hour to build. Even though we were disqualified last year they still let us load test and we did quite well. Last year’s bridge easily passed the lateral load test and failed the vertical load test at around 1700 lbs. The bridge this year performed about the same in the lateral test but unfortunately did not do as well in vertical loading. the bridge only took several hundred pounds before the arch bent and twisted in an “S” shape along the longitudinal axis of the bridge (see below). During our build some of the arches were slightly askew and the addition of weight caused the arch to buckle at these points since it was designed to be in total compression. It was unfortunate that it occurred but there was not enough time during construction to fix this mistake. On paper the bridge performed very well, even better than last year’s bridge, but in practice is where we fell a little short. Next year well be sure to make improvements to the design to cut down on build time and make connections as easy as possible.
Next year the competition will be held at the University of Maryland in College Park, MD. The team has been making steady progress over the years that I’ve been here at Lehigh and participating. None of our team member’s are graduating this year so we’ll all be a little older and wiser next year. I’m hopeful this translates to an even better improvement than the one we made this year!