Birch Truss Bridge

The goal was simple to state and hard to do: design a birch-plywood truss that carries as much load as possible for as little weight as possible, then build it and test it to destruction. The design went through the full engineering process, from first sketches to a physical bridge loaded until it broke.

The finished truss weighed 0.6 kg and held 10.38 kN, roughly 1,700 times its own weight, the third-highest load in the class.

I worked through every stage of the design: researching truss forms and sketching concepts, modeling the geometry in SAP2000, developing the parts in SolidWorks under finite element analysis, then laser-cutting and hand-assembling the final bridge.

The bridge was loaded on an Instron testing machine until failure. It carried 10.38 kN before giving way, and the break came at the crossmembers beneath the load points rather than in the truss itself, meaning the main structure never reached its own limit and the true capacity was higher still.