Analysis Desires

Last week, my group mates and I tested our 2' bridge in a competition against the rest of the groups in our class. Our bridge would have cost over $305,000 to build full-scale, but it only supported 17.4 pounds of sand during the test. This was the first time we tested one of our bridges using the apparatus, and we were able to get a good view of how our bridge failed. This week we will be testing our 3' bridge which was designed completely differently. We decided to cut costs by using different gusset plates and longer chords. We believe our bridge will be able to support more weight than our last bridge. And even though this bridge is a foot longer than the last, it's nearly $50,000 less expensive.

In designing the bridge using Knex, something that is challenging is having to run several tests and analyze each one to determine where the weaker points are. In West Point Bridge Designer, a table of information was presented after each simulated test. The info included statistics regarding each individual chord's tension and compression forces, and slenderness. I would like to be able to determine the tension and compression forces across the top and bottom of the Knex bridges we've been designing, but the problem is that WPBD bridges normally fail because of weak chords giving out. The pattern I've noticed with the Knex bridges is that the joints, or "Gusset plates," have been failing before the chords. I am not sure how we could calculate the tension and compression forces.