40 ft Span Bridge

[JohnDB]

I didn't use written plans. Just back of the envelope, you know 'hillbilly style'! LOL I do have more pictures if that would help. I have an engineering degree, but no registration so my design probably wouldn't help you with the authorities anyway. I didn't include dynamic loading, non-symmetric loading and other things that real bridge design would entail.
But it meets our needs and if there is anything I can share, let me know.

Hard to believe that it was back of envelope design because looking at the cross-bracing I'm guessing that you took into account lateral-torsional buckling? Otherwise, how did you decide on the design of the cross-bracing? I'm really impressed by what you have done.

 

[PoTreeBoy]

Hard to believe that it was back of envelope design because looking at the cross-bracing I'm guessing that you took into account lateral-torsional buckling? Otherwise, how did you decide on the design of the cross-bracing? I'm really impressed by what you have done.

The design wasn't totally back-of-envelope, but I didn't make any drawings. I figured I'd have to make field adjustments anyway, and it's a pretty simple concept. And I didn't have a construction crew that I needed to communicate instructions to.

There were some pencil and paper (gasp!) calculations to determine the dead/live loads, shear and bending, but a rigorous bridge design wasn't performed. I used an old edition of the AISC (American Institute of Steel Construction) Handbook to size the beams and determine the brace spacing. Sizing the bracing was more 'make it hell for stout'.

 

[Magicman]

I really admire your bridge. I have three bridges on my property, but none as nice as yours.

 

[fishdrivel]

I was a Union Iron Worker in younger days.
Bridge building has so many aspects to it that I would not recommend it.
That said, I would build one myself! LOL

 

[JohnDB]

I was a Union Iron Worker in younger days.
Bridge building has so many aspects to it that I would not recommend it.

Good point. Bridges with long slender beams can suffer catastropic failure by buckling, which usually happens without warning. Simple beam calculations are insufficient for that sort of application, so it was good to hear that PoTreeBoy used more than back of envelope calcs

I'd love to know if anyone has used the eSPAN140 bridge design tool at https://www.shortspansteelbridges.org?

That said, I would build one myself! LOL

Me too, that's a great-looking bridge. Big ups to PoTreeBoy.

 

[random]

Random, how about starting a new thread in this section and state your problem. Include a couple of picture and I'm sure the brain trust here will have some ideas to help you. A new thread will probably get you more response.

I'll definitely do that, but when I'm closer to actually doing something about it. Trying to recover from a rather expensive year of projects right now, and it's not quite urgent, just concerning right now. The responses here are giving me an idea of a possible worst-case, so I know what to plan for.

Gotta go get some pics before posting anything too.

Thanks for the info!

 

[PoTreeBoy]

I'd love to know if anyone has used the eSPAN140 bridge design tool at https://www.shortspansteelbridges.org?

JohnDB, I didn't use it. I think I found that after I was well into the project. It looks very interesting.

And thanks to everyone for your kind remarks. I found a lot of useful information people had posted on the web, and decided to try to return the favor.

 

[GreensvilleJay]

nicest 40' homemade brisge I've seen was soooooo simple...
guy took a 'scrap' 40' seacan($2500 delivered),blew 3 big holes in it,each side, laid in 3 sections of 2' diameter culverts, dragged into stream, bermed up the ends as ramps, as he acquired gravelly 'fill' , he dumped it into the seacan. this way 100% of the water went into the culverts.
been there 20+ years,can drive anything over it...

 

[Lil Foot]

Maybe I'm a little dense- If you can drive anything over it. is the top still in place? If so, how did he dump gravel in it? If the top is gone, how does he keep rainwater from filling it up?
Enlighten me please.

 

[fruitcakesa]

Maybe I'm a little dense- If you can drive anything over it. is the top still in place? If so, how did he dump gravel in it? If the top is gone, how does he keep rainwater from filling it up?
Enlighten me please.

My question too after looking up "sea can", AKA "shipping container"

 

[GreensvilleJay]

he cut 3 (maybe 4 ?) holes into the top,so excavator bucket tossed gravelly material into the can,started at one end.Once a hole was full, fill in the next,tamp down the crown.there maybe drain holes,can't member that, but the top was 'decked' with timbers(3x10 or 3x12),so I don't think rainwater was ever a problem. I member driving a loaded 3/4t Chevy PU over it and it was SOLID.

 

[Lil Foot]

That makes sense, thanks.

 

[Mrlunchbox]

Awesome project, thanks for sharing with us!!!