As the National Student Steel Bridge Competition marked its 20th anniversary this year, Bentley was proud to continue as a National sponsor, offering free software and tutorials to participating teams as they worked on their 2011 designs beginning last fall. (See my sponsorship blog). The competition was more rigorous than ever and reached record levels of participants this year—with 201 teams competing in the regional ASCE Student Conferences and 48 teams qualifying for the National finals.

           

 

This year’s problem statement involved a new road in a state park, to access remote areas and including a bridge over a scenic river that carries utilities to both the welcome center and campground. The design/build proposals were to include a deck bridge (“to minimize visual impact”), with clearance for boating and passageways for utilities. Environmental impact considerations lead to additional requirements: only permitting permanent supports on natural levees on both riverbanks, and the requirement for one end of the bridge to be cantilevered to span wetlands.

For the third consecutive year, I happily attended the ASCE/AISC National Student Steel Bridge Competition (NSSBC)—this year hosted by Texas A&M University in College Station, TX on May 20th-21st, 2011. This competition must be witnessed firsthand, to truly appreciate what a challenge it poses to students’ skill in steel design, fabrication, scheduling, and management. Ask any team member, and they will undoubtedly say it is equal parts hard work, hands-on learning, and fun!

48 teams reported to Brazos County Expo Center on Friday, May 20th, for bridge set up and display judging. This first day is as much about scoping out the competition, and gathering ideas for next year, as it is about proudly displaying their own 1:10 scale model bridges.

Saturday, May 21st found the teams at a venue on TAMU’s campus, Reed Arena, for the construction and load testing portion of the competition. At the build stations, 3-5 team members carefully laid out each individual component of their bridges—down to each individual nut and bolt—and then waited for the judges to start the stopwatch.

One or two team members then raced the clock to bring components over to the rest of their fellows in the construction area, with a joint goal of building their bridge in record time. Students ran back and forth with each critical component of the bridge, one bit at a time and in sequence, while the builders grabed each piece and scrambled to build their bridge at breakneck speed.

This year, Lakehead University clocked the best time, constructing their bridge in only 4.74 minutes! 

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 stations. This year’s sway and deflection limits were a full 1/2” less than last year, making the 2011 design challenge still more difficult for the teams.

Over in Load Testing: First, the back span of each bridge is subjected to a lateral load test; decking and 75 lbs are applied, and the sway may not exceed ½ inch. If the bridge passes, then it proceeds to the lateral load test of the cantilever—again, with 75 lbs applied and the sway not exceeding .5”.  For those bridges that passed these two stages, the decking and load are then removed for the final stage.

In the vertical load test, two decking units are placed, with 200 lbs of pre-load on the back span decking unit, and 50 lbs on the cantilever span, to measure deflection. Next, 1600 additional pounds of weight are added on the back span, while checking for sway (no more than .5”) and deflection (no more than 1.5” downward). Finally, another 650 pounds are added to the right deck, for a total test load of 2,500 pounds for these scale model bridges.

Each bridge is ultimately judged on the following steel design requirements: display, construction speed, lightness (lowest total weight), stiffness (lowest aggregate deflection), construction economy (lowest construction cost), and structural efficiency.

On behalf of Bentley, I applaud all 48 teams. Their efforts in the 2011 NSSBC prove that the next generation of structural engineers is well prepared to help design and sustain the world's infrastructure.

The 2011 National Student Steel Bridge Competition overall winners are as follows:

1. Lakehead University

2. Michigan Technological University

3. SUNY Canton

Congratulations to all of the participating teams, for jobs well done!

You can read more about this competition at http://www.aisc.org/steelbridge

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