Spaghetti Bridge Report – Cameron Criddle
SPAGHETTI BRIDGE REPORT – Cameron Criddle
Your report should include sections on:
- Investigation into bridge design and the strengths and weaknesses of
various structures.
- Testing procedures and outcomes from testing.
- Discussion of chosen design and construction of bridge (including
pictures, photos and sketches where appropriate).
- Discussion of bridge failure – where failure occurred and how the bridge
could be redesigned to prevent this failure.
- A bibliography
SECTION 1 - Research (5)
Our research for the perfect spaghetti bridge started with many, many internet searches of bridges that had won their respective categories. One bridge that stood out in particular was the bridge from Norbert Pozsonyi and Aliz Totivan of the Szechenyi Istvan University of Gyor in Hungary. This bridge weighed in at 0.982 kilograms and held a weight of 443.58 kilograms, making the load/mass ratio 452:1 . The bridged used many struts arrange in a perfectly semicircular fashion with an internal support flex pictured below:
[pic 1]
This design showed the critical need for symmetry and the benefit of a semi-circular structure. It also brought to mind the idea of diverting the tension of the centrally-positioned weight away from the centre of the structure and distributing it evenly across most if not all parts of the bridge, leaving no piece a waste of weight, as we found is the case with many Parker- and Pratt-style truss bridges[1]. We then decided that an under truss would assist in this diversion of tension, and were helped by Bridge Basics[2] in determining that a type of truss called a half deck truss would be best for a semi-circular design (pictured). [pic 2]
SECTION 2 - Testing of spaghetti types, configurations, and glues (30)
- The testing began with trying out different types of spaghetti.
Glue | Mass held up (kg) | Mass held sideways (g) |
Araldite | 5 | 800 |
Weld bond | 1 | 100 |
PVA | 1 | 100 |
Hot glue Brand 1 | 6 | 350 |
Hot glue Brand 2 | 6 | 400 |
- The next stage was to determine what was the strongest glue available to us, while remaining accessible and quick-drying. Below is a table of our findings:
It is obvious from the table that Araldite, a commercial brand of epoxy that dries in under 5 minutes, had the greatest strength overall. However, the hot glue brand 1 and 2 outperformed the Araldite in
-Why other designs were bad, and our better
-Why tubular spaghetti is best, while others failed
-Why epoxy is best over other glues