# Make a bridge out of popsicle sticks homework

1. Feb 26, 2006

### marshmallowchicken

Hey all,

I've got a project that I have to do. I have to make a bridge out of popsicle sticks. However, it's a competition and only the winner receives full credit. The bridge with the highest ratio of weight held to bridge weight wins.

Weight Held (Pounds)
------------------------- = Bridge Ratio
Weight of Bridge (Grams)

Here are the specs:

---Thickness: Max 1"
---Length: 14"<X<18"
---Width: Max 6"

Substructure (Optional)
---Depth: Max 3"
---Length: Max 14"
---Width: Max 6"

Superstructure (Optional)
---Height: No Max
---Length: Max 18"
---Width: Max 6"

There will be a whole in the center 3/8" to 1/2". The bridge will be threaded onto a rod followed by a small piece of wood (To even out the pressure a bit) and then a bolt.

________________________________
| | | | | | | | | | | | | | | | | | | | | | Bridge
-------------------------------------

-------................| |............-------
\......./................| |.Rod.......\....../
.|.....|.................| |.............|.....|
.|.....|.Supports....| |.............|.....|

Any ideas, suggestions, advice, or help is appreciated.

Regards,
marshmallowchicken

2. Feb 27, 2006

### dicerandom

A buddy of mine won one of these things (except with balsa wood) in his statics class. He attributed his win to two factors:

a) He designed the whole bridge in CAD.
b) He used Gorilla Glue as the adhesive.

3. Feb 27, 2006

### marshmallowchicken

Oh, sorry, I guess I forgot to post it.

Materials:
Posicle Sticks: No Max
White/Wood Glue

Also 2 of the large flat surfaces of popsicle sticks may not be glued together.

Thanks for trying at least.

Regards,
marshmallowchicken

4. Feb 27, 2006

### civil_dude

One thing to remember is that the distance between the top chord and bottom chord of a truss type bridge needs to be maxed out in the middle. So, if you are only going to use a road deck for the structure, you only get 1" of separation. I would look at some sort of bow truss and be sure that the deck distrubutes the point lode along the entire truss.

5. Feb 27, 2006

### civil_dude

Also, build the bridge to the minimum span. It appears that there is a maximum and minimum length. Find out the exact rules.