This weekend I returned to my alma mater, the University of Michigan, for the North Central Regional student conference. It was the first time that I had attended the annual Steel Bridge and Concrete Canoe competition in at least five years. The last time, I helped a team rebuild their broken canoe with left over steel bridge parts. See April 18, 2010, “It Broke!” This year I was on hand to volunteer as a steel bridge judge.
As a competitor, I could never understand why the whole steel bridge competition went so slowly. We knew the rules forward and back, had trained to construct the bridge in record time, and had load tested to the limit (and subsequently failed the bridge with two weeks to go). Fast forward to this weekend, and I felt much less confident in the much changed rules and more skeptical of the bridge designs pushing the limit.
On Friday night, the judges met with the team captains to clear up any rule interpretations. At that moment it seemed evident that the teams were versed on this year’s requirements. After the meeting, the judges went to check out the loading irons and other judging accessories. This year’s lateral loading requirements and bridge height required us to retrofit the lateral loading rig. Fortunately, the UM team was on hand to do some last minute welding for us.
The next morning I was tasked with managing the load testing. I got the job because I had brought some dial gauges that we could use to measure the bridge deflection. When I arrived at the competition site, everything was just in pile in the corner of the small room assigned to the load test. A couple other judges and I started untangling ropes and sorting the equipment. By the time the first team had constructed their bridge, we though we were ready.
It wasn’t until the first bridge came in that I realized what kind of responsibility I had as a judge. Firstly, we wanted to be safe. We tried to identify locations to install stanchions that would catch the bridge if it did fail. Since that wasn’t practical in all locations due to cross-bracing and truss diagonals, we also placed stacks of buckets below the metal grating on which the angle irons would be placed. The process of adding these safety measures was time consuming and required a lot of judgment calls.
We also had to make sure that the weights were safely applied. That meant restricting how many of the 30-lb angle irons we allowed the students to apply at a time. Application of the load had to be done very carefully, because if the dial gauges were knocked it would mean that the entire process would have to be restarted from the beginning. It took us about an hour and a half to fully test the first bridge alone.
Fortunately, we were quickly able to work out all the kinks in our system by the second bridge. Eventually, we caught up to the backlog and finished the competition before 5:00. Unfortunately, our timing was assisted by disqualifying one team. I felt bad, because it was obvious that they had spent a lot of time on their bridge. They failed the lateral load test, and that confirmed that the bridge just wasn’t safe for the full loading.
The day went quickly for me. I wish we had had more time to explain to the students some of their mistakes. I think the judges were more intrigued by the deflected shape of the bridges than the students. They just wanted to win; we were excited to see lateral torsional buckling and double curvature.
To those students I was able to talk with I stressed how valuable this experience is. I feel that my own steel bridge experience prepared me for industry better than any single class. It’s also great these students volunteer their time just for the sake of competition. You won’t find that enthusiasm for extracurricular activity in the “real world.” I think I’ll be back next year to share in the excitement again.
