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FoBoT

FoBoT

No Lifer
Apr 30, 2001
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my 6th grade daughter is doing the science olympiad , bridge building

they build a wooden bridge to hold 15 Kg over a 350 mm span. the bridge that does it and weighs the least is the winner

the rules are very specific and detailed

anyone here done this before? do you have a winning design? any websites?

triangles - triangles - triangles ?
 
Toastedlightly

Toastedlightly

Diamond Member
Aug 7, 2004
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I'd use triangles since you are using wood. I did something like this like 6 years ago. Make sure that all joints are almost perfect.
 
S

simms

Diamond Member
Sep 21, 2001
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Triangles are the most stable shape to use. Hold on while I do some research. Pontifex will let you experiment with bridges. As a 1st year engineering student, I had to build a bridge for a competition, using trusses and steel.

Generally what will work best is an overhead bridge, with an arc to displace the weight. So imagine an bridge that is curved, with triangles supporting it. I wish I had pictures though.

Simon
 
A

aplefka

Lifer
Feb 29, 2004
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Arched Triangles (see Paris in Hunchback time) > Arches > Triangles > Circles

Haven't had this since 8th grade, sorry.
 
FoBoT

FoBoT

No Lifer
Apr 30, 2001
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i was thinking circles, but i am not sure about making circles out of wood. it looks like they use balsa wood mostly, i dunno how circles of balsa will do. maybe laminated circles, that might be something to try
 
T

TitanDiddly

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Dec 8, 2003
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Circles would be very difficult, I think they get the wood in little strips. I'm sure it's been done though. If they get sheets, they can cut circles out of it.
 
FoBoT

FoBoT

No Lifer
Apr 30, 2001
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the basic reading material they gave us says: suspension bridges > arch bridges > beam bridges

the thing here is, it is NOT about building a super duper strong bridge , it only has to hold 15KG , it isn't to see which one can hold the most weight, it is who can build the lightest bridge that can hold the 15 Kg

so i think some type of triangley arch would be good. i still have to go through all the rules , they are pretty specific
 
A

aplefka

Lifer
Feb 29, 2004
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Yeah, I remember doing a toothpick mini-model that only weighed like 17g and we could hold around 130-150g.
 
FoBoT

FoBoT

No Lifer
Apr 30, 2001
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Originally posted by: simms
Triangles are the most stable shape to use. Hold on while I do some research. Pontifex will let you experiment with bridges. As a 1st year engineering student, I had to build a bridge for a competition, using trusses and steel.

Generally what will work best is an overhead bridge, with an arc to displace the weight. So imagine an bridge that is curved, with triangles supporting it. I wish I had pictures though.

Simon
Click to expand...


that is what some of the examples i saw looked like, since it has to be the lightest to hold just the 15 Kg , i think materials will be as important as the design itself. one thing i read said something about some special hardwood from the Carolinas , stronger than balsa and lighter than poplar. it is probably expensive though.
 
J

J0hnny

Platinum Member
Jul 2, 2002
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When I did this, one of the rules were no arch supports were allowed. I did this exact same thing before and our bridge won for my school.

Remember to use a I-beam type design for the platform. Like a said before, trusses are the strongest given the requirements. It's hard to build a suspension bridge though for a project like this.
 
mcvickj

mcvickj

Diamond Member
Dec 13, 2001
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I competed in Science Olympiad from 6th grade to 11th. Our two best events was the tower build and scrambler. I was part of both. I will have to see if I still have any of my notes. I'm a packrat so I might still have something around.

Try to use as little glue as possible. It really helps with the weight. One of the things we liked to do was build tiny triangle gussets inside the angle to help beef up the joints. Make sure to use a very sharp razor blade or exacto knife to get a clean cut. You don't want to crush the balsa wood. If you have two very flat cuts the glue will do better. Make sure to take notes when your putting things together so when you test your bridge you can duplicate it again for the competition.

Go over the rules 3 times with a fine tooth comb. They were very specific when I was building. Laminated anything was out of the picture. When we were shopping for supplies we found this balsa wood that looked like I beams. We started to build a tower out of the items but after reading the rules we found a section talking about such things.
 
FoBoT

FoBoT

No Lifer
Apr 30, 2001
63,084
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we started doing some practice today and my daughter glued her fingers together :roll:
the teacher got some really hot shot airplane glue at the hobby store, but the first 2 pieces my daughter glued, she squeezed them together with her fingers, and her fingers wouldn't come off the joint, :laugh:

luckily , the store only sells that glue if you buy the bottle of stuff that takes it off/de-glues skin. it still took about 10 minutes to get her fingers apart
 
FoBoT

FoBoT

No Lifer
Apr 30, 2001
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Originally posted by: sygyzy
You are allowed to help your daughter?
Click to expand...

they are required to build it before the competition and bring it. so they can have help, i don't know yet if the rules specify to what level they can have help. i am not going to build it for her, it is her thing, i am not the kind of parent that does their kids stuff for them and i don't have time.

the teacher said they should practice and expect to build 2 of each design, one to test before the competition and one to take, if the test turns out to succeed
 
M

Martin

Lifer
Jan 15, 2000
29,178
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simms beat me to it. that west point bridge building software is nice to play around with. Once you have somethign good in that, try to replicate it using wood.

gl
 
FoBoT

FoBoT

No Lifer
Apr 30, 2001
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this link has some of the info, but i don't see the entire rules online. i have a paper copy they gave my daughter

suspension is out because the only materials allowed are wood and glue
 
S

simms

Diamond Member
Sep 21, 2001
8,211
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Originally posted by: Martin
simms beat me to it. that west point bridge building software is nice to play around with. Once you have somethign good in that, try to replicate it using wood.

gl
Click to expand...

UofT Engineering = :thumbsup: :beer::D
 
R

Rufio

Banned
Mar 18, 2003
4,638
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your daughter is going to have a kickass bridge.

and the other kids will have Sh!thole bridges that can't hold a feather......because they didnt' have the power of ATOT behind them!!!
 
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