Balsa Wood Bridge: 202 Pounds

This is a bridge that Michael and I built and tested in our high school engineering class. Overall it had a mass of 85 grams (0.19 lbs) and held 202 lbs. We used wood glue to connect the pieces of balsa wood.
Restrictions:
- No more than two pieces of balsa wood could be laminated together with wood glue
Thanks to Chris for filming!
Tested on 12.13.2010

[@carmelpule6954]

The success of this loading was due to the fact that the suspension point was right on top of the bridge where the joints were in compression and the only tensioned joints were the horizontal lowest part. If the suspension point was on the lower horizontal part so that it was pulling rather than pushing on the bridge, this bridge would have failed before. Students should consider carefully whether to load the bridge by pushing on it at the highest points or pulling on it from the lowest point as it does make a difference.

[@jjsrt8]

After unloading the platform and reloading it you had already stressed the wood. So it probably could have held more

[@michaelrouse7959]

I few weeks ago in my PLTW high school engineering class I made a truss out of balsam wood that weighed .0088 grams and held 350 lbs.

[@brianhymer3427]

Bridge efficiency is 1,078... That's Pretty good, but I hear some balsa bridges in Science Olympiad last year got scores of 1,500 to 3,400 (!). My bet is you could have held a lot more weight if you were using sand (thus gradually adding weight) instead of heavy Dumbbells. Still, that was wayyyyy cool, thanks for sharing!

[@katepurrkins6672]

This is so amazing! :o

[@fischer1672]

My popsicle stick bridge in middle school weighed 146 grams (0.32 lbs) and used 98 popsicle sticks. It was held by just normal Elmer's School Glue. It held 200 pounds for 5 minutes and didn't break. It was tested 3 times and got over 200 lbs each time, but we didn't have any more weights so we had to call it at 200. (We stacked 50 textbooks which each weighed exactly 4 lbs so that was 200 lbs.) It had a span length of 457.2 millimeters (18 inches) and had 76.2 millimeters (3 inches) of the bridge resting on the test tables on each side.

[@hopeandsad872]

Please share me your project.

[@grimmtrotzits]

I did this in middle school! Ohhh I want to make balsa wood bridge again!!

[@Infipark]

amazing architecture.

[@badw01f23]

that is amazing. just wow

[@maitreyeerele]

That was amazing! xD

[@pranavhegde98]

That is frickin awesome

[@vladislavsbudovskis4846]

The issue of this bridge is that the load is in upper side of the bridge which means it can take more than usual bridge construction. So if you normally put loads where they use to be, on drive way, I think you will have max one third of your result.

[@kika7995]

We made a balsa wood bridge in school. Ours weighed 16 grams and held 960 pounds. This bridge looks alot cooler than ours did.

[@jasonoverstreet6270]

You can't just put weights anywhere like they did. That's not an accurate test. Bridges aren't designed or intended to have mass load on top of the truss like that. The criteria should have been laid out from the beginning so the design could take into account where loads would be placed.

[@mlist09]

5:39 was the best part :D

[@MargaritaInclanRobredoXD_IXXI]

Awesome

[@Good13055Productions]

My bridge held 55 punds balsa wood 3/32x3/32 squar root wood with 10 inches long 6 inches heigh and 3 inches with and it weight 4.2 grams

[@outdoormike0505]

the teacher took photos and video. I'll probably upload it when I get it. The bridge had much different dimensions though. it was 10.5"x4"x3.5"

[@outdoormike0505]

I just made a similar one that i tested today! I have the school record at 435 lbs

[@fordaiffa6022]

Very nice What was the balsa wood specifications n size Surely the fiber stress was below critical Great project though !

[@stephenimsong3462]

Not bad, I expected a truss that big would take a larger load honestly.

[@rishapkumar5039]

the bridge i made held up till 467 lb total weight of bridge was 170 grams efficiency 2457.9

[@Mike-cp7zf]

that was amazing! how did you guys build that?

[@JakeyMeisty]

Its just 1x1 inch strips of balsa would glued with wood glue

[@RomeoB1999]

daniel . is it possible you could give me the blueprints to how you did this? or where you got it from ? this could be our best bet of winning our competion for school

[@RomeoB1999]

well thank you anyways it helps

[@fudge817]

Did the bridge have the requirement that no two touching pieces could be parallel?

[@markbroadwaywms1927]

What was the overall length of the bridge?

[@JacobEllinger]

if the wight is not on the expansion then it's not a very good bridge test.

[@skyecleckler6380]

I have to make a finished balsa wood bridge by January 24 for science Olympiad with an eighth grader

[@nurshuhadarazali]

how long do u take to make this bridge?

[@MyNameIsBob212]

1 kg = ~2.2 pounds. So 202/2.2= 91.8, about 91.8 kg, Meaning it was able to support about 1080 times its own weight.

[@dicey78]

"what was that" lol

[@Thrallsm8]

i put thick cement and it held a ton :P

[@qurilishmexanikasi3013]

Prosta klasss

[@fspwork]

what size of that balsa wood?

[@andrewroesch26]

I built one that weighed point 88 oz. And held 450lbs

[@STAxTartaglia]

Any details on the dimension?

[@keira.8400]

What type of bridge design did you use? I’m making a bridge for my science class and want to hold a lot of wait:)

[@wenzhig4242]

光考虑承载力和自重没有意义，还需要考虑宽度限制，高度限制，动载还是静载。我的1.2m长，10cm宽，10cm高，能承受至少40kg静载，5kg的边载（同时支座有175Hz的1cm振幅震动）荷载不会掉下去。自重186g It is no sence only consider the resistence and selfweight, width limit, height limit, dynamic load or static load also make influnce . mine is 1.2m long, 10cm wide, 10cm high, can hold at least 40kg static load, 5kg dynamic load (while the bearing has a 1cm amplitude vibration175Hz)and load will not fall off . weight 186g

[@BAMBAMJROCK123]

wats the name of the song at the end

[@JakeyMeisty]

What was the overall efficiency score?

[@alissazhao9808]

+dm__ this bridge was only .19 grams heavy? thats would be insane

[@mohdshukur8701]

when the load impose at the top the member of compression and tension difference figure already that not exact correct way to impose the load to this test.

[@lordpickle1935]

Ok so can you make an open file in the program ModelSmart3D pls like in 2 to10 Days

[@potatohamlin5242]

It holds 5 pounds I’m happy... 5 seconds latter ITS HOLDING MORE THAN 9000 POUNDS

[@phoebeats]

cool to bad I don't have enough time in my class to do that

[@papasmurf7668]

U just wanna see it break!

[@drpwn100]

There is no way that only weighed 85 g

[@Charix460]

nuts'

[@travisclampittpanell2235]

Im not the only one who realizes they were at 95lbs going 5 additional lbs at a time, why they didnt just go for 3 25lbs weights and then add another.. wouldve followed or at least picked up the progression better...

[@sylasherndon9967]

this is very hard to lift

[@wingedfury1000]

it held 202 pounds.

[@ckozan]

Kinda defeats the whole purpose of a "bridge" when there is a giant column in the center (eye bolt) .. Can't use the bridge if the road is blocked!

[@donnisonable]

Hackers...

[@Space_Cat969]

I live being a virgin

[@cristopherraljevic4754]

you spelled my name wrong its Cris not Chris

[@Good13055Productions]

and im 13

[@tylerdurden629]

Now you are 20

[@freddy7694]

@@tylerdurden629 you mean 21

[@fluffy_noelle]

1 dab 0n th3 h8rz. H0w ab0ut y0u?

[@fluffy_noelle]

lol sorry my pet lama walked on the keyboard XD