I have always wanted to build a model suspension bridge, and finally I have finished one. This is a popsicle stick suspension bridge. I created it from scratch, coming up with the design on my own. After testing it to failure I learned quite a bit about how suspension bridges react to loads. This model suspension bridge uses popsicle sticks as the main building material. The decking is cardboard, and the “cables” are 550 parachute cord (military surplus).
Testing the Suspension Bridge
Here is the video of the bridge being tested to failure. I have two different angles showed right after each other. I think this video is very enlightening as to how a suspension bridge reacts to a load.
It appears that the bridge failed due to uneven loading. The weights leaned to one side, and I over-corrected as I kept adding weights.
I did not come up with a good method of securing the cables to an anchor. You will notice in the movie that the ends of the bridge lifted up as the middle bent down, until a certain point where the ends of the deck pressed up against the cables themselves. If I were to do this again, I would have the cables already pressing down on the ends of the deck to help secure it in place. I think this would provide much better support to the bridge rather than what I did.
This suspension bridge was very flexible, as you can tell from the video. I read an article about building model suspension bridges that said it was difficult to get them flexible enough. Also, I did not have any hangers (vertical cables hanging off the main cables) on this bridge. I did not make any mostly because of the great difficulty in making them even and I did not know a good way to attach the hangers to the main cables. In real life, the cables are metal and have metal clamps and other devices that make this process easier. But I was using parachute cord.
Plans for this Suspension Bridge
Do you want to build a model of a suspension bridge? They sure are fun and are great to look at when you are finished. My models are always functional, which means you can test them as well. While I do not have blueprints for this particular suspension bridge, I do have plans for a smaller one. You can check them out here:
Suspension Bridge Blueprints