In the midst of our Studio and Construction Systems work, our other classes continued ahead at full steam. In Structures 1, after having learned all about beams, columns, etc. and how to calculate their forces, we were tasked to construct a pedestrian bridge to scale. This bridge was to be loaded using a machine in the shop, to test its capacity. The structure also had to include a covering, but had to be open at the very center where the load would be placed.
I teamed up with classmates Jesse, Lauren, Erik, and Miguel for this project. We began with a simple arched design, with a flat path placed below rather than above the arch. Originally we had misunderstood the assignment and designed the bridge such that the load would be placed on the arch. Our hope was that the pedestrian walkway below would act as a tension member to hold the ends of the arch in place (as it had not material to brace against as it might in a building). We constructed the bridge out of laminated sheets of MDF, and this was ultimately our downfall.
When tested, the bridge failed much earlier than we had hoped or anticipated – very quickly the laminated sheets sheared apart, as the glue was not able to hold them together under the stress of the load.
Back to the drawing board for the second and final design, knowing this time that if we were to laminate the structure, we would need to provide some sort of cross-member to keep the material from shearing apart.