Brain trust - Bridge steel support load question.... NDR!!!

Is this c channel because you speak of ears at the end, almost sounds like shelving steel for pallet racks? If it is c channel what is the actual area you are crossing assuming some amount of steel is going onto ground on each side. One thing I would do imams I will try to paint a picture I would go out 1/3 distance from end and bring a leg back at a 45 deg angle back toward the banking on both ends so the weight from the top would deflect down and back towards the bank edge sort of like in post and beam houses beams come down at a 45 back into the carrying beam. Doing this on both ends will reduce flexing. Personally I would do this with I beams which are stronger. I would also bolt angle iron across bottom every two feet, as the top flexes down the bottom will twisting or out with weight. You need to build that really rugged for 1000 pounds IMO
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Could be, it is a structural "C" channel salvaged from job site at some point in the past 60 years. I agree with your design, that it would be strong. I'm not worried about the strength of the channel if I build it with the 8" side vertical, which seems like I'll be doing, since I've not been able to convince myself that it is strong enough the other way.
 
WEll there's always the drawbridge idea lol I could get u some crane cable
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I have thought about that, a drawbridge would eliminate the concern that in high water the pressure woudl move it off its base. I'd rather just be able to take the tractor or truck and drag it away from the stream in predicted high water. We ususally have advance warning and it doesnt' happen often.
 
What about an old flat deck trailer? Prospectors do that up here so they can skip the permit process for building a bridge.

Mike
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That is part fo the reason that I'd like it not fixed in position. It may not matter to the powers that be, but to me it woudl be better than having it on a solid footing. The alternative is to get a piece of heavy equiptent and make a place to ford the creek - and I'm not doing that (nor would I ever get permission).
 
Hmmm...I'd go in the driveway, Block up each end, and drive across the middle with my wife watching. The number of head shakes is a real good indication of the inches of deflection.
 
Hmmm...I'd go in the driveway, Block up each end, and drive across the middle with my wife watching. The number of head shakes is a real good indication of the inches of deflection.
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That is close to what I was looking for. If you could give me the number of head shakes, I'd be getting somewhere.
 
Todd:

Found some notes from a site visit last spring. The "new" technique many forest operators are using for permanent crossings is to construct a simple bridge using concrete waste blocks as footers/abutments. These are available at very low cost as a by product of concrete manufacture, and are pretty standard in size.

Doesn't answer your questions about the steel, but may be useful information for creating permanent troll habitat.
 
Todd:

Found some notes from a site visit last spring. The "new" technique many forest operators are using for permanent crossings is to construct a simple bridge using concrete waste blocks as footers/abutments. These are available at very low cost as a by product of concrete manufacture, and are pretty standard in size.

Doesn't answer your questions about the steel, but may be useful information for creating permanent troll habitat.
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I'm not sure I follow. A pile of broken block as a footer or the whole bridge?

My goal was to not disturb the watercourse in any way and completely span anything that would count as wetland (I know that this may not count for the powers that be).
 
The concrete waste blocks are solid concrete blocks that are something like 4 feet long, and about 1.5 feet wide and tall. (Just guessing, and dimensions may vary, but it's a big solid rectangular block of concrete.)

They are placed, preferably in the upland. Can be partially buried if need be. They give you a solid footing for whatever you use as stringers. Much cheaper and simpler than pouring a slab, or constructing a log crib.

It won't be necessary if you have bedrock on both banks, but if you need to place your bridge from soil bank on one side to soil on the other, it will give you a solid base.

I'm looking for an online drawing or photo, but can't come up with one.
 
I'm not sure if I'm more disappointed that you needed to ask or that this hasn't been suggested yet.

Bridges? We don't need no stinking bridges!
1969-1.jpg

 
Also, rule of thumb for sizing a crossing to avoid both hydraulic issues and blocking of fish passage is that the span of your crossing should be 1.5 times the "bankfull" stream width.

"Bankfull" in New England is the stream width during a typical annual flood--the high water event you get every year.
 
Tod,

You might consider these as options;

(A) use the channel in the vertical but trim the ends to lower the entry point. You would want to add a 1/4x2 plate to tie the ears together along the tapered ends.

(B) use the channel in horizontal but make the length two pieces welded together to form an arch adding a full length rod to each ear to form a complete truss. You would not need much arch to gain a lot of strength. A couple braces forming vee in the center of the length extending up to the channel might be desired as well as the full length rods.

View attachment bridge.jpg View attachment bridge2.jpg

PS. The truss would also provide a slightly better troll habitat. ;>)
 
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The concrete waste blocks are solid concrete blocks that are something like 4 feet long, and about 1.5 feet wide and tall. (Just guessing, and dimensions may vary, but it's a big solid rectangular block of concrete.)

They are placed, preferably in the upland. Can be partially buried if need be. They give you a solid footing for whatever you use as stringers. Much cheaper and simpler than pouring a slab, or constructing a log crib.

It won't be necessary if you have bedrock on both banks, but if you need to place your bridge from soil bank on one side to soil on the other, it will give you a solid base.

I'm looking for an online drawing or photo, but can't come up with one.
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Gotya Jeff!!! Those are commonly used to build retaining walls near my folks in upstate NY. I'd like to stay as modest as far as a footing as I can.
 
I'm not sure if I'm more disappointed that you needed to ask or that this hasn't been suggested yet.

Bridges? We don't need no stinking bridges!
1969-1.jpg
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Yee-Haw. I did accidently once drive the tractor over the bank into the creek. It wasn't a huge production to get it out (needed the truck), but Gus was about 3 and on my lap at the time - so it made an impression on him.
 
Also, rule of thumb for sizing a crossing to avoid both hydraulic issues and blocking of fish passage is that the span of your crossing should be 1.5 times the "bankfull" stream width.

"Bankfull" in New England is the stream width during a typical annual flood--the high water event you get every year.
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Due to the nature of what I have to work with, I exceed that by quite a margin, that is one of the reasons I got the steel, so I coudl make a long damn bridge. Maybe rather than a bridge I should call it a ramp to convey the non permanent nature.
 
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Tod,

You might consider these as options;

(A) use the channel in the vertical but trim the ends to lower the entry point. You would want to add a 1/4x2 plate to tie the ears together along the tapered ends.

(B) use the channel in horizontal but make the length two pieces welded together to form an arch adding a full length rod to each ear to form a complete truss. You would not need much arch to gain a lot of strength. A couple braces forming vee in the center of the length extending up to the channel might be desired as well as the full length rods.



PS. The truss would also provide a slightly better troll habitat. ;>)
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Nice drawings Dave. Given what I have and that I don't want to have to work within the channel/wetland (see Jeff's comment), I think I'll go with the bridge just sitting proud on top of the bank on each side and make a couple little ramps to drive the 11" up (8" steel, 1.5" nailer, 1.5" deck) if that makes sense. If I went with what you draw that would be very nice and I'l only need 6 feet or so max to span, but I'd be doing the work within the stream bed - as it stands I'd be going from lawn to lawn if the span is 10-12'. I really like the #2 option if I had a welder that would be cool.

P.S. bedtime for me - date with deer tomorrow, we have nice snow for stillhunting that is rare here.
 
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The c channel is stronger with the long part on the verticals. The Deck trailer doesn't buckle when loaded because the axle supports the middle of the trailer frame. If you take away the middle support and run 1000 pounds across 16 ft span it will fail, the c channel might help under it but I would still 45 back to bank with 8x8 notches and bolted
 
Tod,

If you have enough material length, make the ramps part of the main bridge beam. Put the taper up, again add a 1/4x2 piece to tie the ears together and give you a surface to bolt decking to.
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You may just have done it today Dave - Thanks!
 
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