Elevated Bridge B/C

[croman74]

Would top 1700 efficiency make you medal or place in the top 6?

For B division, I'd definitely say that's top ten. I have a really hard time predicting what will be the threshold for medaling in either division for Elevated Bridge. There have been high scores this season, but many of these high scores have been from schools that didn't advance to Nationals.

I also have to wonder if the Georgia humidity will drop the bridge scores down. Any guesses on that one?

That might be a small factor. But if teams want to avoid that, they should put rice in their bridge container. That's a good point to bring up.

[gandhiji]

yay i just tested my bridge and it weighed 9.4 g and held 16.4 kilos before breaking for a score of 1565 not including the extra weight it held

[croman74]

Are you preparing for nats now?

[cypressfalls Robert]

is it better to pour the sand fast...or pour slow; to evenly distribute the sand around in the bucket attatched to the loading block?

[andrewwski]

Doesn't matter how you distribute the sand - it all translates into a force from a single point, as it's all carried through the chain into the loading block. Just pour into the center to minimize oscillations.

The best way seems to be to pour quickly in the beginning, and then slow down toward the end.

[gandhiji]

Are you preparing for nats now?

yea i am

[Allirog24]

Congrats on making Nats!

[dholdgreve]

is it better to pour the sand fast...or pour slow; to evenly distribute the sand around in the bucket attatched to the loading block?

I'm sure there are as many opinions out there as there are... but I believe that consistency is far more important than speed. If hand loaded, minimize the thumping of the sand hitting the bottom of the bucket, and keep the bucket from swaying. If machine loaded, find a speed that minimizes the sand being released in waves. Once these skills have been mastered, release it as quickly as possible within the above parameters. There is always a specific reaction time... the time between when the bridge breaks, and the judge releases the cut-off. It may only be a 1/10th of a second, but it's there... more sand will go into the bucket and be counted as load if running quickly, than if barely dribbling in.

As for slowing down at the end, I don't buy it... the longer a structure must resist a load, the more likely it will fail.

Much more important than the speed of the loading is the levelness of the bridge, the levelness of the testing platform, the angle of the hole through the loading block, and even the length of the eye bolt. If the loading block does not sit level on the top of the bridge, or the testing table is not level, or the hole is not drilled perfectly at a 90 degree angle to the block, the eye bolt will not be perfectly vertical. If the eye bolt is not perfectly vertical, when a load is applied it will be pulled vertical, causing an unbalanced load between the two sides of the bridge. This not a good a thing, and will cause the bridge to "torque." The longer the eye bolt is, and the tighter the hole is, the more this condition is exacerbated. I've see eyebolts that are as much as 12" long, and have hung as much as 1" out of plumb

So... take a pocket level or torpedo level with you and check the testing platform, and how the top of the bridge looks before placing the loading block... you probably will not be able to get the testing platform adjusted, even if it's out of level (not likely at Nats... theses guys are GOOD) but you may want to rotate the bridge 180 degrees to see if one way sits better than the other. Same goes with the loading block. Place it, but then look at it from the end... Does it look plumb?... I mean REALLY plumb?... if not, rotate the block and look again. If the bridge is not symmetrical, rotating the block won't help, but if the hole is slightly off of 90 degrees, here will be one rotation that will be better than the others.

Good Luck at Nats guys!

[blue cobra]

Will the rules stay similar for next year? I'm on this event, but I do nothing. My partner has his heart set on an arch, which he seems close to perfecting, but I'd like to play with simpler designs over the summer. The rules should stay similar enough that this won't be a waste of wood, eh?

[bob3443]

Will the rules stay similar for next year? I'm on this event, but I do nothing. My partner has his heart set on an arch, which he seems close to perfecting, but I'd like to play with simpler designs over the summer. The rules should stay similar enough that this won't be a waste of wood, eh?

the rules will probably change next year(saying that if bridge is an event next year which i think it will be)
Building is never a waste of wood because you get experience and know how much glue to use, size of wood, etc. you can also test if an arch is indeed better than a non arched bridge.

also on how fast to load, i usually just load fast with my partner, but the day of competition, my partner never showed up so i had to go myself. although the weight goes to one point, if you only load on lets say the left half of the bucket, the loading block might somehow slip a mm to the left, and make it weaker or something(just saying!)