Meet Your Steel Bridge Chair
About Steel Bridge
Most of the following information was obtained from the official steel bridge rules: HERE
Officially known as the Student Steel Bridge Competition, it is the premiere inter-collegiate steel bridge competition. In which civil engineering students design, fabricate and construct a steel bridge. After construction the bridge is then tested at the regional competition by applying a given load. If the bridge performs well enough, it will be tested again at the national competition. The competition is sponsored by the American Institute of Steel Construction (AISC) and the American Society of Civil Engineers (ASCE). It is also co-sponsored by the American Iron and Steel Institute and the James F. Lincoln Arc Welding Foundation.
There are two levels of competition: regional and national. Regional competitions are held in conjunction with ASCE regional conferences. Only one bridge per university is entered into the regional competition, and a university can only compete in one region. Invitations to compete at the national level are extended only to the winner from a region with two, three or four participating universities, to the top two teams from a region with five to ten participating, and the top three teams from a region with eleven or more participating universities.
2012- 2013 Team
The 2013 Kansas State Steel Bridge team is happy to say that our bridge has been completed! We are currently practicing building our bridge for construction time and will be competing at Nationals in Seattle, WA here in a few weeks. We placed 1st at regionals and are looking forward to competing at the national leve.
Below are a series of pictures that document the team’s progress this year from “a pile of steel” to the bridge we currently have. We have tried to describe using pictures some of what went into fabricating this year’s bridge.
The first picture is steel donated by our sponsor, Salina Steel, shortly after it arrived in the CE shop. Prior to being cut, the pieces come in 20-24 foot lengths. Also note the full length jig that we constructed. Using this 21 foot jig, we were able to help align all of the bridge members for one side of the bridge. Next picture is of the steel pieces after they have been cut. Each piece is labeled with a number and letter that correspond to our labeling system so that they can be retrieved later on in the fabrication process.
Here is a 1/4” diameter pieces are bent around a jig using an acetylene torch. These pieces will be used for the webbing of our leg members. The webbing for the cross members were bent in the same manner, but with a wider jig. The second picture is of one of the legs, about 50% complete. It will still have bracing along the other two sides and connections welded on to accommodate the top and bottom chord members.
There are the truss hangers will later be welded to the top and bottom chord members and connect using dovetail connections. Next our some of the dovetails, which were cut by the Mechanical Engineering shop using a CNC mill. We received them in 6 inch lengths, which were later cut down to sizes ranging from 3/4 inch to 1-1/2 inch depending on the application also the end view of the dovetails.
A large majority of the dovetails used on the bridge. In total, the 2011 bridge used about 50 dovetail connections. Using a dovetail and one of the pipe-notched end pieces, we welded up what ended up as the truss hangers and connections. This is the final product (minus finish welds). The hangers are ready to be tacked into place using 21 foot wooden jig.
Here is a better view of what each truss member looks like. Each hanger has two dovetails and will be connected to the top and bottom chords. This is what the truss members look like sitting in the jig. They are ready to be tacked in place once they are aligned and leveled. However, the chord members are not ready yet and are shown below.
These are the new, twisting connections we designed for this year’s bridge. They went through three different prototypes until we decided upon this final design. They were made using a CNC lathe by AMI and were cut out of 1-5/8 inch diameter round bar stock. Here are 25 of the 28 twisting connections we used this year. We are very pleased with the low tolerances and quick construction speed that these connections provide. The twisting connections were shrink fit (slip fit) into the top and bottom chord members using an acetylene torch. The extra heat from the torch allowed the tubing to expand and then the connections were quickly forced into the end of the tube before it cooled. The connections were slip fit into place, they were welded and ground down for extra strength.
Once all the chord and truss members had their connections finished, they were laid out into the jig and tack welded in place. Here you can see the shape of one side of the bridge coming together. The middle picture is what one side of the bridge looks like after it is completed and removed from the jig. The second side was made in the same fashion. The final picture is of the cross members were welded using another jig and then fit to the bridge on a case-by-case basis.
The picture on the left end is one of the completed cross members, which is 6 inches deep. Next is a picture of both sides of the bridge connected by a few cross members, the first time it actually looked like a 3-D bridge. The final picture is of the bridge a further along. As you can see, the cross bracing is all set into place except for the cantilever cross bracing.
The cantilever cross member bracing, finally complete. There are a lot of members on the cantilever due to the very strict lateral bracing requirements for this year’s competition. This also marks the end of structural fabrication meaning the bridge is ready to be load tested!
There is a close-up of a typical hanger and chord member connection. Each connection has a bolt connecting two members which satisfies the rules. This is the backside of the same connection shown. Note the stops welded on the back which allow the builders to quickly assemble the twisting connections and truss members. Last is a picture of the close-up of the most complex connection on the bridge. This is where the lateral pull test will occur and features three cross members coming together at a single point.
The completed bridge; sign plate and all. This is shortly before we load tested the bridge. The second picture is setting up the grate and string potentiometers (used for measuring deflections) for the load test.
During the load test, the load was placed on the mid-point of the backspan to simulate worst case loading. As you can see, the tethers are slack, indicting the fork lift is not holding any weight. The second picture is of a number of angle iron to finish loading the cantilever portion of the bridge to 700 pounds. This, combined with the backspan load, equals the 2500 pounds total that the bridge will carry at competition.
Overall, the bridge weights about 215 pounds and had an aggregate deflection of 0.399 inches (worst case loading) during our load test. We are still working on construction time, but hope to build the bridge in 12 minutes using three builders.
We placed first overall at the Regional Competition held in Norman, Oklahoma.
We placed 23rd out of 46 teams at the National Competition held West Lafayette, Indiana.
We placed second overall at the Regional Competition held in Carbonadle, Illinois.
We placed 25th in Las Vegas, Nevada.
We placed second overall at regionals at the University of Arkansas.
We placed 14th out of the 43 North American teams at Gainesville, Florida.
Official ASCE/AISC Student steel bridge competition website: Official Site
Current copy of the rules: Rules
Competition Guide: Guide
Kansas State University – Student Governing Association
Kansas State University – College of Engineering
Kansas State University – Department of Civil Engineering
Kansas State University Transportation Center
The Monarch Cement Company
Wildcat Construction Inc.
Bartlett and West Engineers
Sloan, Meyer, and Hancock Consultants
Constellation Design Group
Salina Steel Supply Inc.
Advanced Manufacturing Institute
CE Advisory Council
Dr. Hayder Rasheed
Dr. Jacob Najjar
Dr. Mustaque Hossain
Dr. Sunanda Dissanayake
Dr. David Steward
Dr. Asad Esmaeily
Dr. Bob and Anita Peterman
Bruce and Jeane Johnson
Dr. Hayder Rasheed