16 September 2019
Challenge to destruction
That was fun! Apparently spaghetti bridge building is a 'thing' on many architecture degree courses these days (and presumably structural engineering courses too). But the concept managed to pass me by until we turned up for a recent dinner party.
We were divided into two teams with the following brief:
span 400mm
carry 3Kg
using spaghetti and a glue gun
must enable a wind up car to freely drive across (bridge surface provided in cardboard)
LIGHTEST BRIDGE TO MEET THE ABOVE WINS
Being 16:00 on a Sunday and school the next day, pretty quick D&B solutions were needed.
Internet research was forbidden, so a lot of guesswork was required as no one had seen this challenge before (apart from the host), nor did we have knowledge in the typical structural characteristics of spaghetti (other than that it snaps easily in bending) or for that matter the glue in the glue gun.
Here is Team A in action (didn't have time to make up exciting team names):
We went for a fairly minimalist triangulated diamond formation, attempting to combine a bit of structural rationale, working with the full spaghetti lengths (top and bottom chords are full length spaghetti pieces), a lot of triangulation, and achieving a bit of aesthetic clarity with the diamond look for good measure.
Both teams took about 3 hours to design, build, eat and drink. Seeing as our team A's effort appeared particularly fragile there was surprise all round when it effortlessly held the 3kg bucket and water.
TEST TO DESTRUCTION
You can see from the photos of the team A collapse that it was the bracing between the top chords that buckled first (on the right hand side) - in hindsight the bridge might have carried a lot more if we had doubled up those top compression bracing members!
Much fun had by all, and the kids especially enjoyed the testing to destruction:
Since the party we've looked into other spaghetti bridge designs, and found various claims o the world record (presumably no internationally recognised brief standard). But several bridges manage over 600kg, perhaps not surprisingly using a bicycle wheel type solution.