Last weekend Lucas, Sam, Zack, Wade, and I participated in the first annual Google Games at UIUC.
The were three main events: puzzles, Lego bridge building, and a Wii tournament. For the puzzle event, the organizers gave each team an envelope containing six problems to solve. Our team started out well—I was the first to complete a paper-folding puzzle, and we quickly completed two others— but we failed to complete the final three. One was a Sudoku variant in which we had to fit the letters GOOGLE into a hexagonal grid. Another was a logic puzzle in which we had to determine from a set of clues where people lived on a map. I had completed three of four programming sub-problems involving loop expansion when time ran out.
Unfortunately, we were not allowed to keep the puzzles, and the organizers never announced the correct answers. No doubt they wanted to keep people like me from posting the questions and answers online, but, still, it would have been nice to experiment with the questions at home.
We lost in the first round of the Wii tournament, so while the other teams competed in Wii tennis, we played ping-pong in another room.
I thought the Lego bridge building was the most interesting part of the games. We had to build a bridge that the organizers would judge based on aesthetics and strength. I had to span 24 stubs, rise at least four blocks high, and allow an eight-stub-wide car to cross it. In addition, we had only a set number of basic Lego pieces (no Technics), and could only trade pieces with an equal number of stubs.
Unfortunately, we did not have a cohesive plan for our bridge and ended up with a very, very disappointing and ugly mess that I am ashamed to admit I had a part in building. However, the problem is certainly interesting: how can one build a weight-bearing structure out of materials that perform very poorly under tension? The winning team's bridge held 102 pounds because the core of their main span consisted of 2x6 plates turned on their side. This is an excellent idea, and it got me thinking of other possible designs.
Last night I downloaded the Lego Digital Designer and started building bridges. I feel the following would hold a lot of weight:
The main span is modeled after floor joists. It is made up of laminated 2x8 plates connected at the joints with 2x2 blocks. These long plates perform very well under tension, and the 2x2 blocks prevent twisting and "delamination". The span rests on footings made of normal 2x4 and 2x2 blocks. The green 1x4 blocks keep the span from sliding off the footings and help prevent the footings from falling over.
I know a few engineers read this website; what do you think of the design? I have posted the Lego Digital Designer model file if you would like to play with it.