My name is Mason Jordan. I built a bridge out of Popsicle sticks. It is about eighteen inches long and five and a half inches high. I made it for a 7th grade class extension project. It has to be at least 18 inches long. There was no height limits and has to hold one hundred pounds. For your bridge to hold one hundred pounds you must do a lot of research first. The main thing that I learned was that triangles are one of the strongest geometrical shapes, and the kind of glue that you use does matter.
Step 1: Design Your Bridge.
I used Instructables to search what types of bridges people were building. I used this to help me figure out which type of bridge I wanted to build. There are four main types of bridges. The Arch bridge, Beam bridge, Suspension bridge, and Truss bridge. I based my bridge off of the truss bridge. The part that I did different was the top. The second picture shows what I did differently. I glued the popsicle sticks so the thinnest part was facing up because it can withstand more weight. What I did on the top was an idea I had in my head.
Step 2: Getting the Right Materials
These are the materials that you will need. I used about 150 popsicle sticks. Something to clamp the popsicle sticks together, like a clothespin. I used Gorilla wood glue. I wouldn't recommend hot glue because it will flex and twist with pressure. Old newspaper will be necessary to put underneath your bridge while drying in case any glue drips.
Step 3: Getting Started
I started off with building the triangles. Keep in mind that triangles are really strong. I clamped the corners where I put the glue so it was nice and tight. Triangles are the one of the strongest shapes because any added force is evenly spread through all three sides. The second picture is what the triangle looks like after the glue is dried and the clamps are removed. I generally kept the clamps on for at least 30 minutes. You want to make sure that you have a lot of clamps so you can make more that one triangle at a time.
Step 4: Getting Bigger
I continue to keep working. I connected three triangles at the base by putting popsicle sticks on both sides to make it as strong as I possibly could. The next step was to attach some popsicle sticks to the top to connect the points and make a replica for the other side of the bridge.
Step 5: Moving Forward.
I connected the two sides by placing popsicle sticks across the two sides with glue. There was one problem, I should have measured the popsicle sticks before I glued them because I still had a little bit hanging off the side.
Step 6: Adding the Top Layer
How I added the top layer? First I added some cross beams (four cross beams). I added the cross beams so I could add some more popsicle sticks along the sides at the top (in third photo). I added those so I could make some beams that were horizontal and on its edge. That would increase the weight it can hold.
Step 7: Final Touches
For my final touches I didn't do much. I put more glue where it was scarce. I also added more supports were it looked week. I noticed that some popsicle sticks had some gaps between them. So I decided to fill in the gaps by cutting some popsicle sticks up to the right size and putting them in there and sealing it with glue. Now time to test.
Step 8: Testing Phase
At first before I started, I looked at my bridge and thought if I put 100 pounds on top, it has to at least bend. We are going to test in class so I only wanted to put up to 100 pounds on it. I started with around 35 lbs. Nothing happened. I went up to around 60 lbs. and still nothing happened - no sounds or bending. Then I went up to a little over 90 lbs. Nothing at all was happening. So then came 100 lbs. We placed it on and nothing happened. The bridge held 100 pounds successfully.
Step 9: Your Final Product.
My bridge had many parts. The most important part was the triangles. Some other parts were beams, supports, and the base and top.