OK, I want to make a little bridge over the creek to access the other side to be able to mow my food plot at home with the garden tractor. I've read up on bridges, the liability and the environmental laws and I'd (still) like to build a small movable (not anchored) bridge that can span the creek, which is neither deep nor wide.
I have two pieces of steel that will work in at least one way: 2 - 14' pieces of "C" channel - the channel is 8" on the long side, the ears are 2" and the minimum thickness is 1/4", so a stout piece. I would build a 2x6 wood deck on top. Originally, I was thinking to put the long (8") side on the vertical, which would be plenty strong (but would have the downside of being tougher to deal with : 1) harder to build, 2) higher to get up on and 3) taller side profile in the rare case the creek comes up out of its banks). I think they may be strong enough to span the creek with the long side on the horizontal (and the ears down), which would be really nice for a lot of reasons (1, 2, 3 above).
Question, is there a standard of deflection that I can measure to evaluate what sort of load will give a safety margin for failure? I can set them across supports and apply a force similar to the tractor and measure deflection easily (I've done it by having Jen and I jump on them in the center, but I'd like to have something more to go on). I think for designing wood floor joists in a house they design for less than 1/360 deflection, but I don't care if the steel bows or jiggles, I just don't want it to fail (failure would not be too dangerous, just suck). I also don’t need to use the whole 14’ and can shrink it down some if needed. Suggestions??????
I have two pieces of steel that will work in at least one way: 2 - 14' pieces of "C" channel - the channel is 8" on the long side, the ears are 2" and the minimum thickness is 1/4", so a stout piece. I would build a 2x6 wood deck on top. Originally, I was thinking to put the long (8") side on the vertical, which would be plenty strong (but would have the downside of being tougher to deal with : 1) harder to build, 2) higher to get up on and 3) taller side profile in the rare case the creek comes up out of its banks). I think they may be strong enough to span the creek with the long side on the horizontal (and the ears down), which would be really nice for a lot of reasons (1, 2, 3 above).
Question, is there a standard of deflection that I can measure to evaluate what sort of load will give a safety margin for failure? I can set them across supports and apply a force similar to the tractor and measure deflection easily (I've done it by having Jen and I jump on them in the center, but I'd like to have something more to go on). I think for designing wood floor joists in a house they design for less than 1/360 deflection, but I don't care if the steel bows or jiggles, I just don't want it to fail (failure would not be too dangerous, just suck). I also don’t need to use the whole 14’ and can shrink it down some if needed. Suggestions??????
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