From left, the UAH Steel Bridge Team is Michael Krauz, Jake Villarreal, Jon Torres, Matthew Hussak, Kevin Wang, Zach Riley, Blaise Brown and Sterling Riether.
UAH
A 20-foot long, 4-foot wide, 4 1/2-foot tall steel bridge weighing around 120 pounds has been created by The University of Alabama in Huntsville (UAH) Steel Bridge Team for the American Society of Civil Engineers (ASCE) steel bridge competition in Chattanooga, Tenn., Thursday through Saturday, March 19-21.
This is just the second year of competition by the UAH team, advised by civil engineering assistant professor Dr. Hongyu Zhou and civil engineering lecturer Dr. Ashraf Al-Hamdan.
One of the biggest challenges for the competition is that each bridge member must fit in a 3-foot by 6-foot by 4-inch box, and each of these members are then bolted together to make the 20-foot spanning bridge.
The steel bridge competition is one of the two major ASCE competitions, the other being the concrete canoe competition. The ASCE partners with the American Institute of Steel Construction (AISC) in the competition, which is an intercollegiate challenge requiring civil engineering students to design, fabricate and construct a 1:10 scale steel bridge according to pre-set rules that are modified yearly.
Participation requires that the team compete through three phases: design and testing, fabrication, and assembly. In the first phase, students use classroom knowledge to design and optimize a bridge structure to carry a 2,500-pound load.
"This is completed using STAAD.Pro, a finite element analysis software, to develop multiple bridge models from which the final bridge can be chosen," says Matthew Hussak, a civil engineering graduate student from Pittsburgh, Pa., who is the team's bridge chairman. "In this phase, we also prototype connection concepts and test their performance in tension and/or compression, depending on what is required for the bridge."
Team members are:
- Jake Villarreal, bridge design 1 leader, a civil engineering junior from Pensacola, Fla.;
- Sterling Riether, bridge design 2 leader, a civil engineering sophomore from Chelsea, Ala.;
- Zachary Riley, fabrication leader, a computer engineering sophomore from Huntsville;
- Kevin Wang, competition team captain, a computer engineering sophomore from Queens, N.Y.;
- Michael Krauz, team member, a mechanical engineering junior from Decatur;
- Jon Torres, member welder, a structural engineering sophomore from Lexington, Ala.;
- Hunter Fesmire, member welder, a civil engineering freshman from Chattanooga, Tenn.;
- Blaise Brown, member, a civil engineering sophomore from Oneonta, Ala.
Team members weld the components of their competition bridge.
UAH
After design, the students enter the fabrication phase, where they grind, weld and fit the parts together to form the bridge. Finally in the last phase, students put the parts together to build the designed bridge.
Bridges are scored in the contests by how long it takes to bolt together, the total weight of the bridge and the deflection of the bridge under the specified 2,500-pound load.
"One of the biggest challenges for the competition is that each bridge member must fit in a 3-foot by 6-foot by 4-inch box, and each of these members are then bolted together to make the 20-foot spanning bridge," says Hussak, who holds the only elected position on the team. "This member restriction has to be considered from the beginning of our design and becomes a major controlling factor in determining how our final bridge design will look."
The UAH team's bridge is optimized to reduce overall weight while limiting deflection.
"To accomplish this, we used 10 different sizes of tubing, each varying in diameter and wall thickness, to get the lightest bridge we could make," says Hussak. "One of the major differences of designing this bridge and a full-scale bridge is the connections we use. We have to design small-scale connections that require only one bolt to hold them together, yet they still need to be strong enough to withstand the competition load."
To gain strength, the team used more complicated, hand-calculated connections this year and machined all connections with a low tolerance, so that everything fits together tightly once the bridge is built.
"Then we had to find someone to machine them for us, which was an enormous challenge because there were 212 of one type that needed to be machined, and 175 of another type that needed to be cut out," says Hussak. "All of that work takes time, which costs us more money. In the end we used a former UAH student, Arthur Wang, to cut the 175 pieces, and Skip Swaim, who's a machinist with the Rotorcraft Systems Engineering and Simulation Center at UAH, was able to machine the 212 connections."
The team had to overcome hurdles in that what's designed is never exactly what appears after fabrication.
"We spent a lot of time fixing the bridge after each member is fabricated, " Hussak says. "Sometimes we have to shorten a member, other times we have to bend it a little to line up, but in the end we have to find a way to get the bridge to come together while still complying with all of the rules. It can be the most challenging and frustrating part of everything, and usually requires a lot of trial and error to make the bridge flat, stable and to have everything line up."
Nucor Steel of Decatur provided the structural steel for this year's bridge and Fastenal Co. provided all required bolts. Additionally, the Office of the Dean of Engineering and the Civil Engineering Dept. provided support to offset expenses for travel, manufacturing and equipment.
The experience benefits team members beyond the competition, Hussak says.
"We offer members the opportunity to learn as we design and build the bridge," He says. "Whether it's exposing them to structural engineering software for the first time, explaining the concepts of steel design, or teaching them how to weld, everyone learns a lot each year."