A1-WETZEL

The goals I had in mind for my bridge design were:

• to build a two-lane truss bridge without the use of pillars
• for each shape made by the truss to be a triangle--the strongest shape
• for the truss design to include several small triangles stacked upon each other

My bridge design from the "Drawing Board" view.

A truck crossing the bridge in "Test" mode.

A table displaying the "Load Test Results" regarding each member of my bridge design.

While designing my bridge, I decided that instead of using small triangles, I might benefit from using larger triangles as a way of dispersing weight across the structure. I also learned that a member is too slender to be useful if its slenderness rating is above 300. Taking advantage of this information, I decided I could make my bridge stronger by keeping the slenderness rating below 200 for each member.

Currently, my bridge design cost is $585,603.91. After learning more about bridge design and developing strategies for keeping costs low and strengths high, I think that I could potentially lower the cost of this bridge to around $380,000--a difference of over $200,000.

From designing this bridge, I have learned that the weaker area of a bridge can be the top of the truss. For bridges whose trusses are above them, I'd always believed the bottom of the truss to be weaker. By experimenting with different bridge designs, I've notices that during failed tests, the top of my trusses were almost always the weaker sections. This is something I will try to understand better as I research bridges and learn more about successful bridge designs.