Designing a Spaghetti Bridge to Support 2kg of Sand: Tips and Restrictions

[hmilstein11]

Hey y'all, I am in the 11th grade and have been assigned a spaghetti bridge project. Our teacher taught us nothing about bridges or structures, but only the basic forces. We were instructed to research designs of bridges online but every website or forum that I have found has had a different answer as to what the best bridge design is.

Here are some of the restrictions and rules we must follow:

Bridge Length - minimum of 30cm
Bridge Width - minimum of 5cm
Bridge Height - no limit
Roadbed Length - minimum of 30cm
Roadbed Width - minimum of 5cm
Total Mass - maximum of 50g
•A 5cm x 5cm x 1.5cm wood block must be able to be moved along the roadbed across the full length of the bridge
•No portion of the unloaded bridge shall be at a level below the top level of the testing table
​

Basically, we have to be able to load 2.00kg of sand into a bucket that is hanging from the center of our bridge, with a loading time of only 2 minutes allowed.

Failure is defined as the inability of the bridge to carry additional load and is decided by the judges. The judges will count to 3 seconds after the sand is loaded for the bridge to pass as holding the load.

Also, we have been given some restrictions for our materials, here are a few:

Spaghetti must be regular (not tubular, not thin or thick)
Preferably no hot glue, because it may add extra unnecessary weight to the bridge
Cannot paint or stain the bridge
Cannot impregnate the bridge with glue
Glue must be confined to points of contact between pieces of spaghetti
Use of glue accelerator is prohibited
Lamination is Prohibited - Lamination is defined here as any spaghetti-to-spaghetti contact area that exceeds 1.0cm in length
Multiple contact areas of parallel of near-parallel spaghetti are allowed along the length of the stick as long as each one is at least 3.0cm away from any others on that stick
Lap Joints are allowed
Mitering of joints is allowed at any angle as long as the 1cm rule is not violated
Water and steam to bend spaghetti is allowed​

Anything will help, and thanks in advance!

-Holden

 

[Doug Huffman]

I would make my own spaghetti! Use lots of egg protein. The usual recipe is of flour and water only. Stir the mixture to develop the flour gluten as much as possible.

Use the smallest amount of glue at the joints as possible to prevent lozenging, the conversion of a well triangulated joint into a many sided joint.

Sounds fun!

 

[SteamKing]

I don't understand the requirement to be able to move a rather small wooden block across the bridge, which must also be designed to hold a bucket with 2 kg of sand suspended from the middle of the span.