Designs B/C

[embokim]

do you have a picture of this bridge design?

[chinesesushi]

do you have a picture of this bridge design?

No. I doubt anyone who has a bridge that scores >2000 would post their design, unless they have a bridge that scores >3000 Also, there was a discussion about how the scores would be distributed here: http://www.scioly.org/phpBB3/viewtopic. ... 0&start=15

[retired1]

Keep it simple.
One way to think of it is to look at towers. Now shrink it to 5cm front to rear and then expand the base to the 35+ or 45+ cm. It only needs to be 5 to 10 cm high. This was the starting point for the B team that won the trial event at national. Check an earlier post for how good it was. Second place was the ultimate in KISS.
As Jander says, build something, see where it breaks and make modifications. Start with hobby shop quality balsa.

[embokim]

I just tested a new design and it weighed 17 kilograms and held 14.65 kg. I thought that was a pretty good run. Its score was 861.

[UQOnyx]

Does anyone have any personal experiences with the sizes they would be willing to share? I wasn't going to do this event, but in the end I had to do it, so I think I'm a little behind. I went through the threads and I have a few questions..
I even looked up some of the facts, but honestly I didn't find any satisfactory answers. The first and most important question was what are the main forces coming into play in the bridge? I've only had any experience in Boomilevers, so I don't know if any of my knowledge carries on to this event :/. From what I understood, the "top" part of the bridge is compression, and the "bottom" part is in tension. Is this correct? If so, should I be building the bridge around these two members? Like in Boomilever, there were usually two main members, the compression and tension, and they would be built using very specific types of woods and sizes, while the smaller members such as trusses and smaller members would be smaller and less minor parts. Does this apply for bridges as well?

[chinesesushi]

Does anyone have any personal experiences with the sizes they would be willing to share? I wasn't going to do this event, but in the end I had to do it, so I think I'm a little behind. I went through the threads and I have a few questions..
I even looked up some of the facts, but honestly I didn't find any satisfactory answers. The first and most important question was what are the main forces coming into play in the bridge? I've only had any experience in Boomilevers, so I don't know if any of my knowledge carries on to this event :/. From what I understood, the "top" part of the bridge is compression, and the "bottom" part is in tension. Is this correct? If so, should I be building the bridge around these two members? Like in Boomilever, there were usually two main members, the compression and tension, and they would be built using very specific types of woods and sizes, while the smaller members such as trusses and smaller members would be smaller and less minor parts. Does this apply for bridges as well?

Yes you are correct, the top of the bridge is in compression and the bottom of the bridge is in tension. You should be building the bridge around these two members. Most of the things in boomilever apply to bridges as well. I believe that buckling forces come more into play in bridges as usually (depends on your design) the two compression members aren't at a right angle to the test supports so I think the buckling force may be magnified.

[UQOnyx]

Thanks for the reply.
I noticed that there isn't much talk about Warren trusses. Is there any particular reason why one would prefer not to use Warren trusses? From my research, I thought that Warren trusses might be optimal.

[chinesesushi]

Thanks for the reply.
I noticed that there isn't much talk about Warren trusses. Is there any particular reason why one would prefer not to use Warren trusses? From my research, I thought that Warren trusses might be optimal.

I think it's because for the competition, the bridge is supporting a point load. I'm sure that you could get a high efficiency with a Warren truss, but not necessarily the highest possible due to design constraints. I think the Warren truss is better suited to something that has to move across the bridge, like a real bridge, while here in Science Olympiad, all we need to do is support a point load. That's why I think the Warren truss is not used as much (like I said though, I'm just theorizing )

[matthew101802]

Apparently my bridge keeps swaying side to side when I build it. Any help on that? I don't have a picture ATM.

[retired1]

Most people will build 1 side at a time while on a flat surface, then glue the sides together as required. Use sections of Styrofoam or wood for spacers for this step will help.