They were only glued together at the ends, per specified rules, although we learned later there was an unwritten rule that you could not stack pieces to make a thicker member, so we were penalized slightly..

This next pic shows you the setup for the test: a 5 gal bucket is placed on the bridge & you slowly pour sand in until the bridge breaks. Max weight of 20kg. (my suggestion to dump a 50# bag all at once was not accepted)

We were unaware that the footing for the bridge would be 2″X2″s, & as fate would have it, they hit right in the middle of our trusses. You can see how it is flexing in between trusses along the bottom chord. This was ultimately the failure point. Otherwise, the bridge actually stayed very straight underneath the load.

Here you can see it holding up well:

In the specs for the bridges, the organizers did not specify a minimum height requirement, & 1 of the other teams took this to the extreme & built basically a pallet:

It was a great learning experience for us & has encouraged me to start a club next year where we do little beyond build bridges & towers!

Garrett Adds
Thanks for sharing! It is too bad about the unknown rule about doubling up the sticks. Your lateral bracing on the top and support for the bucket look really good. Another thing that probably would have helped is to have lateral bracing on the ends of the bridge as you look through it. This would stabilize it and help keep it from leaning or falling over sideways. You mentioned that the bridge failed because the supports (2x2s) caused a lot of shear pressure on your bottom chords.

That beam bridge is interesting, and it reminds me of a conversation I had recently with an engineer. He was saying that in real life they try to design bridges so that the mode of failure is gradual, and not sudden. It is hard to do this with model bridges, as most often they look pretty good and before you know it they just explode. But that beam bridge has enough flexibility built into it that you can definitely tell when it is having problems way before it actually breaks. Flexibility is the only plus to using hot glue. I’ve seen a bridge hold up a lot more weight simply because it did not break at the joints due to the flex in the glue than if it had used a harder glue, such as wood glue or white glue.

Ice Cream Stick Tower

Here is an ice cream stick structure made up from 200 sticks, which carried 30kg. of weight.

Submitted by Sandip Babar.

Questions from Garrett

What glue did you use to build this tower?

Was this just for fun and what inspired your design?

Did you learn anything from building this structure that you could share with the rest of us?

Thanks for sharing!

I like this video because of the commentary. The observers discus their opinions about why each bridge failed (casually) as the video plays. Notice the comment about lateral bracing on the first bridge. Would you agree with them?

Did you catch how the second bridge failed? This would have been an easy fix, and it just goes to say how you should reinforce the loading area on your popsicle bridges. Take the lessons from this video and use on your own models.

I also appreciate this video because the winner shares my name, Garrett. What do you think made Garrett’s bridge so strong?

Popsicle Suspension Bridge

Catch a sneak peek at one of my newest creations: a model suspension bridge made from popsicle sticks and paracord. This bridge was created as part of a custom project I designed. This idea was one I had been contemplating for some time. I found a simple way to construct a suspension bridge and this is the result. I have some ideas how to make this even better which might take some time to finalize.

You will be able to find a kit for building this popsicle stick suspension bridge in my store soon.

Here is a picture of the Hell Gate model:

frame work started using steel bars welded together

Garrett’s Thoughts
This is an excellent piece of work. Thank you for sending in this photo of the progress you have made so far. I am definitely looking forward to seeing the finished product. What are your plans for it once it is completed? What inspired you to start building this model bridge?

Thoughts About the Design

He states that this bridge should have been able to hold close to 1200 pounds from what he worked out on paper. It only held about half of that weight, which raises a question in me of, “what went wrong?” Also, if the bridge held 600 pounds and weighed 500 grams, it only has an efficiency score of 546. Compare that to my Short Pratt Truss Bridge Updated which had an efficiency score of over 1200. Granted, his bridge was longer, I’d guess around two feet long which is double that of my pratt truss popsicle bridge. Has anyone here been able to achieve a higher efficiency score with a similar length popsicle bridge?

My 1st brigde

Thanks again for all the great info and advice. This project only has to hold 10 lbs. extra credit if it has a 25% or less load capacity percentage. The record in the class on this project is 80 lbs… I’m planning to donate 1$ for every 10 lbs this bridge holds to your web site.

Model Covered Bridge

Thank you for your time and any helpful resources. (I cannot make the Johns
Hopkins nodes and members work….?)

Rainbow Bridge Company

Pin Joint Bridge

I have pointed out the fixed and pinned joints, at least that’s where I remember them to be. It was extremely difficult and painful to drive the pins in, especially when no other tool was allowed, and I had to use my finger for the purpose, but it was very rewarding.

You should try it out sometime.

Warm Regards,
Joseph
P.S. Im the guy in the black tshirt.