Bought some inexpensive plans for a “span” on the net (Rainbow -something, I think). Anyway, the plan for the 27′ bridge is OK at best. Looks like 3 trusses built with 2×6’s, 5/4 decking on those, and a railing. Seems simple, and I’ve heard of boyscout troops nearby having this same plan built and finished in a weekend.
Anyone built one of these? Is there anything I should be wary of?
Thanks for your help.
I’ll be posting pictures of the bridge when it is built. I also have some before/after of the house we’ve ben working on this year.
No Coffee No Workee!
Replies
Is this to be a footbridge, or will you be driving vehicles across it? 5/4 decking for a vehicle bridge seems a bit light to me. We usually use 6x6 timbers.
Can you post a drawing or photo of the trusses?
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
http://pacifi.ca/2060a.html
Okay, gotcha. It's for hula dancers.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Okay, gotcha. It's for hula dancers
Isn't that funny?! It's on the PLAN, TOO!! Anytime there's a picture of the bridge - even the "exploded" view - the hula girl shows up. My buddy and I are hoping that when we get the bridge done, we'll be overcome with hula girls wanting to hula across...(dare I say..."If you build it, they will come"?)
I'll try to post the "plan" they sent. It's kinda ...er... crappy
No Coffee No Workee!
Edited 6/25/2009 8:38 pm ET by Jed42
>I'll try to post the "plan" they sent.
Keep in mind that it's probably copyrighted material - posting anything with much detail might be frowned upon by the copyright owner and/or Taunton.
Don
Oooooooooh....thanks for that. So, I won't be uploading it. Rest assured, it's funny.No Coffee No Workee!
Is this to be a footbridge, or will you be driving vehicles across it? 5/4 decking for a vehicle bridge seems a bit light to me.
It'll be a foot bridge...maybe a riding mower.
No Coffee No Workee!
Forrest built one of those a while back and had a pretty good pictorial going. Give it a search, or maybe the man himself shall show his face and provide a link.
Here's the thread Forrest (McDesign) did on building one:
http://forums.taunton.com/tp-breaktime/messages/?msg=121680.1
did a 24' span once, used two 10 X 10 elm beams set 2 ft wider than the wheels of a pickup, decked with 2 X 4 on edge and runing strips of 1 x 6 strapping perpendicular to the deck .. the "bump" onto a bridge and off of it can be hard on it, make sure you have a smooth transition. Used gabions baskets for the abutments ..
There's a nice, old suspension footbridge over a nearby creek. I've paddled under it when the creek was high enough during Spring flood.
I'd like to go back and check out the construction details -- suspension bridges are the coolest!
AitchKay
i thought you was talking about a bridge
As the web site says these bridges are shallow arch bridges which will push horizontally on the footings (spreading them apart) with a lot of force, even just the weight of the bridge. The stability of the footings are vital to the strength of this type of bridge. This is unlike a normal beam bridge. I don't think the web site emphasizes this enough. If you have bedrock near the surface then connect to that and you'll be fine. If it's soil, particularly clay, then you have to make sure that the footing can't move sideways through or over the soil. The weight of the bridge could cause the footing to creep sideways if they aren't big enough. Any sideways movement will cause the bridge to sag which can greatly reduce it's strength. The bridge's strength is in it's height, not the bending strength of the 2x6s. Unlike most footings the vertical load isn't a big deal. They could even settle vertically without bothering the bridge much. Don't get cheap with the footings.
If the soil is bad or you do get spreading in the future you can tie the ends of the arches together with steel cable (making it a tied arch). The bridge will no longer push sideways on the footings. Use turnbuckles so that you can adjust the tension at any time. You can adjust the height of the arch by adjusting the tension. Of course this may obstruct passage below the bridge and could snag debris if you get any flooding. Make sure the cables are visible if there is passage below the bridge.
Now my tea is cold.
Here's the actual pictorial - http://forums.taunton.com/tp-breaktime/messages?msg=95685.1
I did the deck and handrail in a curve, because I didn't like the faceted effect; also, I made a central spine rather than two arches.
The tension cable I put into the bottom was largely insurance, because I had to move it on a truck.
Forrest - listening to Don Ho, still waiting for the Hula gals to show up
Edited 6/28/2009 8:25 am ET by McDesign
Man, that is great. Beautiful work...and I loved the wrecker installation -brilliant! I liked the tension cable on bottom for insurance and for the fit with the conduit bender.
We're building this over a drainage ditch that we cannot otherwise touch (ie fill in or alter in any way), and we'll be way over the "debris" limit. But thanks for the thought.
RE: the abutments - I'm planning on forms similar to yours, with piers 36" deep x 12-16" dia. Frost is 36" in my neckadawoods (Cincinnati-ish). Were yours similar diameter, or should I consider more?No Coffee No Workee!
Hey Forrest,
Thought I'd let you know...
The guy (Frank) that designed all of these bridges died a couple weeks ago. We sent him a message with a couple questions and got one back from his son that he had died peacefully in his home.
Jed
No Coffee No Workee!
Sorry to hear that - he was a helpful guy - I'll send him a note.
Forrest