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?
Can someone Please answer??? I need to right a supply list for a school project and I dont know that the silver thing on top is! PLEASE ANSWER!!!!!!!!!!!!!
Camby23mvp6 years ago
I am a science/tech teacher and my kids loved this. I had the students draw blueprints prior to building the bridge. Instead of pop sticks, I used balsa wood. This is by far the best project of the year!
drinkmorecoffee (author)  Camby23mvp6 years ago
I'm so glad you found it so useful! Post pictures of the bridges!
what is the silver thing you used to test your bridge? What's it called and where can I find one?
we did this when i was in the 8th grade only with toothpicks. its amazing how much weight those little things can hold with a little glue.
Tutublade5 years ago

in my project the weight had to to held with a hook attached to the middle of the bridge. I am scared of the paddle pop stick which the hook is attached on won't hold the weight and snap. help please

 I just made this bridge for my Drafting class (Im a high school senior).  I added cross beams down the center of it for added support so it wont rack from side to side.  I also added a few more various beams in other spots I thought to be weak spots.  My bridge was 20in long, 4in wide and 5 in tall and only weighed 8.5oz.  I have yet to test the weight.  I will post later when I have results.
drinkmorecoffee (author)  slimnugget155 years ago
*eagerly awaits results*
So I have the results.  I used a 15in board and put it parallel along the top of the bridge and suspended exercise weights from the bottom and it easily held 320lbs and could have done more.  However, my teacher said that was an illegal maneuver becuase the 15in board had to be perpendicular to the top of the bridge so that only 2in of the top of the bridge had all the weight/force on it.  In the end, I retested it and it held and broke at 200lb.  I think hadnt I had the 310lb stress on it before I could have gone higher but hey what can you do.  I set a school record non-the-less!  Thanks for this tutorial!  
setayel5 years ago
what is the weight and length of the bridge?
bradjbear5 years ago
if it is just made of popsicle sticks how does it hold 205 pounds?
drinkmorecoffee (author)  bradjbear5 years ago
It is held together by sheer awesome.

But really, it's the triangles. Read the first couple steps.
I think the key to your success is the clamping. When most schoolchildren do this they use too much glue and weaken the bonds.