ModelSmart3D

First Design

For our first bridge design, we built a truss above and below the bridge to maximize support. We used 1/2x1/2 balsaD2 wood and the bridge could hold two forces of 613lbs or a total force of 1226lbs. This design was 4ft long by 8in wide by 10in tall and spanned a distance of 3ft 4in.

Second design

Our second design used the same trusses as the first except we decreased the span of the bridge to exactly 3ft and then built the rest of the bridge around that distance. To keep the weight centered, we placed the force on two joints diagonal from each other. The bridge was able to hold 669lbs on each joint or a total weight of 1338lbs. This design was 4ft long by 8in wide by 10in tall.

First Triangle Design

For our third design, we wanted to try a different kind of truss and decided on a triangle truss. This design ended up being the weakest of all our designs with only being able to hold two forces of 551lbs or a total of 1102lbs. We decided to try the triangle truss again except with a different scale. This design was 4ft long by 8in wide by 12in tall and spanned 3ft.

Second Triangle Design

Our second triangle truss design was similar to the first design except we increased the height of the bridge to make the sides steeper. This change ended up making this the strongest design out of the four we tested. It was able to hold two forces of 692lbs or a total force of 1384lbs. This design was 4ft long by 12in wide by 2ft tall and spanned 3ft 4in.