19x6ft bridge

[Mike Stanton]

:cool: A guy I know wants to build a 19x6 ft wide bridge over a pond.
What do you think to use for the suports? He has a friend that will mill cedar for him I told him to use pressure treated wood for the suports. Thanks for any help Mike

[Tom Scott]

Personally, for a 19' long bridge I would suggest placing a concrete footing. It's simple to do, and remember that it doesn't matter how good the superstructure is if the foundation fails.

Tom

[Richard Allen]

You didn't say what the intended purpose of the bridge is. If it is for walking than it might be nice to make an arched bridge with a truss support.

[Mike Stanton]

The bridge is fore people only. Mike

[PeterTorresani]

That is a pretty long span for solid lumber. A center support would help a lot if possible. Otherwise, a floor truss type structure would do the trick. The trusses may be ugly, but decorative siding could be applied

I would contact a lumber yard. Many of them have a design person who will do the calculations for free if you buy the wood from them.

I use the PC term design person because my wife used to do this before I forced her to stay home with the kids.

[Brian Walter]

Mike, I would suggest using either treated wood or concrete for the support (abutment). For ideas you might want to take a look at this site http://www.wheeler-con.com/ I used to be head of their engineering dempartment and have lots of contacts if that helps. I'm not licensed to practice engineering in OR so I can't help too much with design.

[Bob Hayles]

19 ft is a bit long for a bridge, even for just foot traffic, without a canter support. It can be done, but it would be expensive to properly build. I'd do a center support on both sides with two #2 cross ties.

BubbaBob

[Richard Allen]

If it is for foot travel then the bridge doesn't need to be flat. The trusses for my home span 24' without any center support and are made of 2x4 lumber. 24" centers and 1/2" ply sheeting easily supports my rather large weight.

I am sure with a little creative design an attractive arched bridge could be made with 2x4 trusses that would have no need for center supports.

Let me clip on my ponytail:

There is also an impact that an arched bridge has on the user of the bridge. As they approach the bridge the bridge becomes more than a means to arrive at the other side. By not being able to see the other side, the bridge becomes an journey to another place. As you cross such a bridge the view widens to take in more of the area making the top of the arch a vantage pint which connects you with both ends of the bridge. Looking back as you have crossed the bridge blocks your view and completes the journey to the "other" place.

The trade off for a more difficult design is that you use less timber, and you have a bridge that is more "interesting".

[Mark Singer]

it is really not a big span to "clear span" I would suggest using a local engineer. It will probably save time and material and you will know it was done correctly. If you want it arched , you can order small glu-lams that are arched. They must not be in contact with the soil...at least 6" raised on concrete footings.

[Lee Schierer]

Covered bridges routinely spanned more distance than what you are asking. Try copying some of their designs. Something like a Burr Arch truss should work nicely for you and be more than strong enough for all the people you can get on it at once.

[Tom Scott]

I agree with Mark and Lee that 19' is not too far to span without supports. I also agree that it would be worthwhile to have an engineer look at it and size the members. I think an arch design would be nice, but more work. You cold also get 2 straight glu-lams to span this, with a wood decking over it. Many times the lumber yard or glu-lam supplier will size these for you.
If you go the wood route, you don't want these in contact with the soil. I am thinking a "U" shaped bracket at the base with a through bolt to support the glu-lam. One end should also be detailed to allow some movement (slip). A bridge is a dynamic structure that will move as load is applied, the wood shrinks/swells, and with soil movements, so thiese need to be accounted for in the detailing.

Tom

[Robert Ducharme]

Is it going to have a little sitting area off to the side at the center for fishing off of? :)

[Mike Stanton]

Thanks for all the help.I got the plans from meisel catalog
I told him where he could get plans for an arched bridge that I made last year the plans are for a 12 ft bridge but he could enlarge the pieces for a longer one. Treated wood on bottom where it hits Mikie