The popsicle stick bridge is a classic science demonstration and competition. Every year many students world-wide build bridges made soley from popsicle sticks and glue, to see which designs can hold the most weight.

We built one, using maybe 140 sticks, give or take a few. Not expecting it to hold much weight, we were surprised by how strong it ended up being! (results in last step)

Step 1: Design Your Bridge

There are many ways to build bridges, both real bridges and popsicle stick bridges. Do some research, be creative, and remember - triangles are strong.
A triangle spreads out weight and is much more stable than a simple rectangle or square support. Be sure to incorporate lots of triangles into your bridge design. More popsicle sticks doesn't necessarily mean a stronger bridge.

In fact, according to the internet, "If there is a single most important shape in engineering, it is the triangle. Unlike a rectangle, a triangle cannot be deformed without changing the length of one of its sides or breaking one of its joints. In fact, one of the simplest ways to strengthen a rectangle is to add supports that form triangles at the rectangle's corners or across its diagonal length. A single support between two diagonal corners greatly strengthens a rectangle by turning it into two triangles."[link]

My design consists of two main bottom supports, and two across the top, and then a lot of triangles across the sides, the top and bottom, and going from the bottom of one side to the top of the other. Very similar to the one in the diagram.

Draw your design on paper, and estimate the number of sticks you will need.
Be creative with your design!

Step 2: Supplies

Very, very simple:

-Popsicle sticks
-Wood glue
-PVC (optional)

Step 3: Constructing

Some things to keep in mind:

A clamp of some sort is a good idea when constructing. I used Tim Andersons method, but bulldog clips work just as well. Clamps are important because most of the popsicle stick aren't flat, so if you don't clamp them when you glue them together your bridge probably won't hold together very well.

Don't pinch your fingers.

Keep your workspace clean! I glued everything on top of a piece of paper, as I have a tendency to get glue everywhere.

Step 4: Start Small

I started by making smaller pieces that would be easier to glue together. I counted out how many I needed and started with that. Once they'd dried just enough to not fall apart, I moved on.

Step 5: Get Bigger...

I glued the smaller pieces together, to create the main supports for the bridge. I then repeated the process and made some slightly shorter pieces for the top.

Step 6: Add Supports

I started with each side of the bridge, keeping them symmetrical, then flipped each side and added more.

Step 7: Add MORE Supports

I added angled supports across the bottom to start with, to hold it together, then across the top.
Keeping in mind the idea that triangles are strong, I added some center supports going across as well as up and down.

Step 8: Finish It Off

I finished it off with some pieces across the top. I'm not sure they add any structural support, but they look good.
I also touched-up on the glue where it was looking scarce, and added more horizontal supports.

Lastly I sanded the top, to make it completely flat so that weight wouldn't be focused on any one point

Step 9: Break It! (Or Try)

This is the last step, obviously.

We decided we'd test the bridge with sand in a bucket. We bought two 60 lb bags of sand, thinking surely my bridge would break under 120 lbs.
It held 120 lbs.
We emptied the sand out, and added 40 lbs of water, then added all the sand back. It still held.

We tried the intern, and it still held.

Two days later we bought another 150 lbs of sand. The bridge finally broke under 205 lbs!

How much does yours weigh?
<p>takes a long time</p>
<p>how long is this</p>
<p>can this support a sphero</p>
<p>i did it</p>
<p>how much weight can it hold?</p>
<p>I think it is really hard to break it and my team is doing the same idea. </p><p>from Me,Rylee Walters and my team ,Yarrh,Caroline and angelina </p>
<p>i cant help sorry </p>
<p>My bridge is a little different. I'm having trouble putting the deck and top supports on. Help?</p>
<p>How about using a glue gun for steps 3-5? It dries faster!</p>
But it won't stick as wet as wood glue.
<p>a glue gun will not hold the sticks together for long. elmer's regular school glue and wood glue soak into the wood (sort of) and that makes it stick better than glue from a glue gun. Yeah, that's my boring glue lecture...</p>
Yah I know
<p>I find that cloths pins are also very effective to hold the sticks together.</p>
<p>nice thank you </p>
<p>I will try it! looks good, gonna save this page on my School USB and make it for STEM.</p>
<p>Awesome idea! I am looking for ideas for our popsicle stick birdge for our group in the STEM unit we have! This really helps! </p>
<p>im making it</p>
<p>do you think it'll work with 100?</p>
Nope maybe 200
I'm going to make it!
<p>try it again</p>
It held 5lbs.
<p>I have made this, it kinda worked.... But it is not that strong</p>
How do you test it? What are the equipments? What is that block on the top of the bridge?
<p>Which bridge design do you think is the best to hold to most weight? Or is it rather the complexity of the bridge that holds a lot of weight?</p>
<p>try a combination of different types of bridges.</p>
<p>Still some free shovacado!</p>
<p>free shavocado!</p>
<p>And all credit to this is maker if i win Thanks for the idea!</p>
<p>Is anyone else doing this?</p>
<p>I am gonna make this in toothpicks i hope it woks</p>
What makes the bridge contain a ton of weight?
<p>I just did our school's annual Busta Bridge Competition - I am the reigning champ, and have been for 2 yrs. since i started doing this</p>
<p>Mine held 492 lbs! Anyone held that much?</p>
<p>i have held 900lbs</p>
<p>I need to make a bridge of physics!!! Now i have an idea of what i can do.</p>
<p>how long did your bridge become? </p>
<p>Thanks for this project. Its working out great so far!</p>
<p>Is it ok to use ordinary glue? and What are those gray things on the side of the bridge to hold it up?</p>
<p>how much did your bridge weight</p>
<p>Is it okay to use ordinary glue?</p>
<p>AWESOME thats really cool! also congrats nicholas</p>
<p>wow this is nice but i would appreciate a video of how you did it or a more detailed one.</p><p>this isn't bad its awesome !!!!!</p>
<p>This project was so awesome when I entered it in the science fair that I won 1st place and won a $100 Visa Gift Card. Yay</p>
<p>Cool design! I'm doing this for class and this would probably work super well! Thanks for the tips and info.</p>
<p>Ty! I got a perfect score because of this! </p>
<p>Thank you for this good instructions.</p>

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