Wooden bridge span question

[tommu56]

RobA

Here are a couple of links

Timber Bridges


and

http://www.fpl.fs.fed.us/documnts/pdf1996/taylo96b.pdf

and

http://www.masterlogger.org/logjam/issues/portablebridges73.pdf


the last one is the type loggers use in my area

edit

here is another

http://www.umass.edu/nrec/pdf_files/skidder_bridge.pdf

tom

 

[mboulais]

another link

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr125.pdf

 

[Wayne_H]

We just finished our fifth wooden bridge this fall. It spans 24 feet. I used two 2x12 glued and bolted together for the trusses, and used a total of four trusses. I used three concrete piers on each side 30 inches deep and about 12 inches diameter. I did not use tubes. I did frame out a sqaure with 2x4's on the top to get it level to I could put steel across the three concrete posts. For the steel I welded two five foot "lentils" that were 3/8" thick. The decking is 2x6. The mule weighs about 1000 pounds, and we have had it loaded with about another 1000, and the bridge does not move.

I'll try to post a pic, hope it works.

wayne

 

[MadJack]

How about 4 telephone poles with 4" hemlock decking? The snowmobile clubs up here use these poles with 2x4 pressure treated and have no problems with three crossing at a time over a 40+ foot span.
The poles aren't even noticed! With the decking spaced at one to 1 1/2" apart, no one gets a foot caught either.

Just a suggestion.


Wayne, awesome bridge!

 

[RobA]

.... It spans 24 feet. I used two 2x12 glued and bolted together for the trusses, and used a total of four trusses. .....

I haven't shopped for lumber for the project yet. Did you have trouble finding 24' long 2x12's? Expensive? Are your joists 16" on center?

I like your overall design. That's exactly what I was thinking. If I could safely use 24' beams it sure would make the pier placement easier.

 

[RobA]

I haven't shopped for lumber for the project yet. Did you have trouble finding 24' long 2x12's?

I called a few local lumber stores. I can easily get 2x10's and 2x12's in 20 foot lengths. That's the longest I could find.

 

[Wayne_H]

No, the best I could find was 20 foot lengths, and they were 8 foot longer than my trailer... So I bought 16 footers, and spliced them with an offset. I used 1/2 inch galvanized bolts every foot, and glued it. The spacing is odd, its about 20 inches, just worked out that way! 0,20,40 and 60 inches.

I have been watching a bunch of almost new telephone poles getting ready to come down, but that's been a four months now, and while the electric company did their thing, the phone company is dragging, so the poles are still up.

But, the 2x12's are nice to work with. Yes, they are expensive, but I have a few sponsors helping with the money on the material.

Wayne

 

[RobA]

Splicing sure would make things easier and a little cheaper. Longer boards are more expensive per foot. Even if I don't splice I was going to use construction adhesive and galvanized bolts to join boards together. Maybe I'll consider splicing. Thanks.

 

[MAYOR8020]

i built a bridge that spans 6-7' w/ 3ply 4x4 @ wheel spacing then decked w/ 2x material. bridge is 12' wide 2-3' off ground i drive tc40a w/ ballast and
pallet box of fire wood over it w/ no problem i built this w/ what i had around
i also drove a 5000lb mini vator over it w/ no prob
bridge has been in svc for 6 yrs. also i just laid it on ground
dws

 

[RobA]

i built a bridge that spans 6-7' w/ 3ply 4x4 @ wheel spacing then decked w/ 2x material. bridge is 12' wide 2-3' off ground i drive tc40a w/ ballast and
pallet box of fire wood over it w/ no problem i built this w/ what i had around
i also drove a 5000lb mini vator over it w/ no prob
bridge has been in svc for 6 yrs. also i just laid it on ground
dws

Any pictures?