Bridge Building 2016

[0ddrenaline]

Can you place the test support anywhere you'd like on the bearing zone. All pictures show it as close to the clear span area as possible, but I do not see any rule saying that it has to be right up against the edge. Im just thinking that if you put it a bit further away from the edge, it will help with the elevation change...

I don't see anything prohibiting that. I don't see a benefit, though. I guess it would decrease the difference in force between the two sides of the bridge, but I don't think the added mass would be worth it.

[DoctaDave]

Can you place the test support anywhere you'd like on the bearing zone. All pictures show it as close to the clear span area as possible, but I do not see any rule saying that it has to be right up against the edge. Im just thinking that if you put it a bit further away from the edge, it will help with the elevation change...

I don't see anything prohibiting that. I don't see a benefit, though. I guess it would decrease the difference in force between the two sides of the bridge, but I don't think the added mass would be worth it.

Keep in mind the increased span also increases the force within the main members given the height stays constant. In order to decrease the difference in force to a significant amount you would have to increase the span a lot.

I would agree with the others in that the increase in mass and force would outweigh any benefits seen from a small decrease in the difference of force of both sides.

[dholdgreve]

Can you place the test support anywhere you'd like on the bearing zone. All pictures show it as close to the clear span area as possible, but I do not see any rule saying that it has to be right up against the edge. Im just thinking that if you put it a bit further away from the edge, it will help with the elevation change...

I believe Rule 5.b.iv says something like "Team members will place the loading block approximately at the center of the test base opening, So unless your bridge is way longer in one direction than it needs to be, I think this means that it needs to be loaded in the approximate middle of the bridge... I'd guess it is up to Event Proctor as to how they define the term "approximately."

[reed303]

Can you place the test support anywhere you'd like on the bearing zone. All pictures show it as close to the clear span area as possible, but I do not see any rule saying that it has to be right up against the edge. Im just thinking that if you put it a bit further away from the edge, it will help with the elevation change...

I believe Rule 5.b.iv says something like "Team members will place the loading block approximately at the center of the test base opening, So unless your bridge is way longer in one direction than it needs to be, I think this means that it needs to be loaded in the approximate middle of the bridge... I'd guess it is up to Event Proctor as to how they define the term "approximately."

elooto was asking about the Test Support, not the Loading Block. Rule 5.b.ii says "Team members must set the Test Support (4.b) in one of the Bearing Zones (4.a.iv).

That is all it says as to where in the Bearing Zone to set the Support. ISTM last year it was OK to have it wherever you wanted, as long as it was within the Bearing Zone.

Of course the nearer the Clear Span Line, the shorter the bridge could be.

[dholdgreve]

Can you place the test support anywhere you'd like on the bearing zone. All pictures show it as close to the clear span area as possible, but I do not see any rule saying that it has to be right up against the edge. Im just thinking that if you put it a bit further away from the edge, it will help with the elevation change...

I believe Rule 5.b.iv says something like "Team members will place the loading block approximately at the center of the test base opening, So unless your bridge is way longer in one direction than it needs to be, I think this means that it needs to be loaded in the approximate middle of the bridge... I'd guess it is up to Event Proctor as to how they define the term "approximately."

elooto was asking about the Test Support, not the Loading Block. Rule 5.b.ii says "Team members must set the Test Support (4.b) in one of the Bearing Zones (4.a.iv).

That is all it says as to where in the Bearing Zone to set the Support. ISTM last year it was OK to have it wherever you wanted, as long as it was within the Bearing Zone.

Of course the nearer the Clear Span Line, the shorter the bridge could be.

Ahhh... Correct, My Bad... although that would reduce the angle, it would lengthen the span, correct? I don't think it would be a good trade out.

[jread]

I am coaching a division B team in NC. We have competed in this event before, and the bridges have always been flat or elevated to the same degree on both sides. The 5 cm change is baffling me with designs. Should we build a bridge like we usually do for convenience (neither side elevated), or should we adjust our designs? I know that the forces will affect members differently on one side of the bridge, but I just wonder if the affects will be negligible enough that we could just ignore the 5 cm rule during designing.

I know teams are pretty secretive about their designs that perform well, but can anyone share an example or picture of what they have changed about the design to adjust for the 5cm elevation?

[JonB]

I am coaching a division B team in NC. We have competed in this event before, and the bridges have always been flat or elevated to the same degree on both sides. The 5 cm change is baffling me with designs. Should we build a bridge like we usually do for convenience (neither side elevated), or should we adjust our designs? I know that the forces will affect members differently on one side of the bridge, but I just wonder if the affects will be negligible enough that we could just ignore the 5 cm rule during designing.

I know teams are pretty secretive about their designs that perform well, but can anyone share an example or picture of what they have changed about the design to adjust for the 5cm elevation?

Although I am a Div C coach I can tell you that we did not drastically change our design (lengthened it slightly and changed the direction of some of the beams) and we are still getting scores over 2,000. The 5cm elevation will cause some differences but honestly we have found them to be fairly minor.

[DumbTro]

Guys what's the best way to hair dry your structure while maintaining most strength and decreasing most weight for the bridge?

[JonB]

Guys what's the best way to hair dry your structure while maintaining most strength and decreasing most weight for the bridge?

This has been discussed in the past and I am pretty sure that almost everyone agrees that using a hair dryer is just not practical in reference to removing moisture from the wood (also, you don't want to remove ALL the moisture). There is really no way to use a hair dryer right before you test your bridge. If you use a hair dryer hours before the competition then it will just reabsorb moisture from the air around it. We have used silica gel in the containers that we transport our structures in but that is just to make sure that there is not an EXCESS of moisture around it (we are in Florida).

[DumbTro]

Guys what's the best way to hair dry your structure while maintaining most strength and decreasing most weight for the bridge?

This has been discussed in the past and I am pretty sure that almost everyone agrees that using a hair dryer is just not practical in reference to removing moisture from the wood (also, you don't want to remove ALL the moisture). There is really no way to use a hair dryer right before you test your bridge. If you use a hair dryer hours before the competition then it will just reabsorb moisture from the air around it. We have used silica gel in the containers that we transport our structures in but that is just to make sure that there is not an EXCESS of moisture around it (we are in Florida).

What I'm trying to say I want to use a hairdryer because maybe its not the best method but it still removes weight from the structure from and increases my efficiency. I got an efficiency of 1724 with my bridge at 8.7 and I held max load. I removed 0.1 gram with hair drying, but I want to know a way that is better and makes me loss more weight. By the way I'm division C.