Howe Truss Bridge

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Have you wanted to make a strong popsicle stick bridge that used 100 popsicle sticks or less? This popsicle bridge was made from 98 unmodified popsicle sticks and WeldBond glue. It was 21 inches long, 4 inches tall, and 4 inches wide. It weighed about 150 grams, and held 140 pounds. With less than 100 popsicle sticks, that is a lot of strength in this bridge. Its efficiency score was 424.

This is the strongest popsicle bridge I have built so far.

I tested this bridge by putting the edges of the bridge on two books, and then placing a scale on the top of the bridge. Then I slowly lowered myself down on the scale with the help of two chairs. I carefully watched the scale to mark the exact spot of failure.

Before this bridge broke, I did hear several loud “popping” noises. This means several popsicle sticks came unglued. I probably could have stopped testing and re-glued those popsicle sticks. Had I done that, the bridge might have been able to hold even more.

That is the value of pre-testing your bridge. Evidently, a couple popsicle sticks weren’t glued on well enough, at least not as well as the others. That means I had several “weak links” that limit the strength of the bridge. Pre-testing allows you to identify those weak spots and fix them, without completely destroying your bridge.

34 thoughts on “Howe Truss Bridge”

  1. That is a good question, John. However, as the scale does not weigh very much (under a pound), I don’t include the weight of the scale in the calculation of the bridge’s efficiency.

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  2. that bridge is tight. i can’t believe it held 140 pounds. is it because the sticks on top were glued tight togeter in threes or twos? i don’t really know much about building except legos…

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  3. whoa! dude i love that tower building thingy.
    ha that is amazing, i think when i get home im going to celebrate my birthday and then build that. it looks amazing. 😀

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  4. Amazing!!!!!!!!!! I can’t believe you built that from scratch!!!!!!! That is definitely going on my science project!!!!!!!!!! Peace out!!!!!!!!!!!!!!!!!!!!!!

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  5. It would have held much more if it had more strength holding the two trusses together. Basically if there were more X’s running through the center. If you look at it in picture “D” you will see only two Popsicle sticks keeping it from just “Falling over” I wasn’t there to see it break, but my guess is that it broke (fell) to the left or right rather than strait down.

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    • Eric, that is a good point. However, I don’t think that is why this particular bridge broke. I think some of the joints in the top chord failed first.

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  6. hey i hav a science project to see if u can build a bridge with the least amout of popsicle sticks and hold the most im excited and i hope ur desings will help mine thx its been a grea help!!

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    • I have never been to a MESA competition. However, it is possible that someone used this design at one of their competitions, but I do not know.

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  7. im building this right now for a project i had to do in class but since i wasnt there i get to do it at home.it looks pretty simple but its not the picture doesnt show every little corner.lol but im trying my hardest

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  8. cool bridge… i hope you dont mind but im gonna need to use your design as a base for the bridge i have to build 🙂

    also,,, i was wondering what type od glue you used ?

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  9. hello? I have a question to ask. how can a vehicle cross your bridge if there’s a cross bracing in the entrance of your bridge? just curious.

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    • You will see this on real truss bridges, that they have lateral bracing at the top of the bridge, but still allow for enough room for cars to pass underneath. In this case, this bridges was not designed to have a car going across it.

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    • Hello–Like many, my bridge has to be designed so a matchbox car can drive across, but with less than 100 sticks. If I had to sacrifice 5 or so sticks, does anyone have any recommendations?
      Thanks,
      –Max

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  10. for my class, i have to build a bridge 20 feet wide, with ELMERS GLUE!! ill never get it done with that. elmers. eww. so i think ill use one of your designs.

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    • Yes, a true wood glue is pretty much always a solid choice. I’m pretty sure I used Elmer’s white glue for this bridge, which is not as strong as a wood glue.

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