Bridge Question

[jmason42]

Hi All,

I have a quick question for you all regarding bridges. I have searched the forums, but have not yet been able to find my answer.

I am in need of a new bridge over a creek at my property. The span is approx. 2 - 3 meters, and the bridge will experience occasional vehicular traffic in the form of pickups/suvs etc. A culvert is not really an option, as beavers would **** it up every season and cause other problems.

I plan on sandwiching some 2x10's (or 2x12's) together to form two beams, and then just use some 2x6's for the deck. My question is as follows: how many 2x10's (or 2x12's) do you think I would need to sandwich together to support the weight of a full-size pickup? I will be using carriage bolts to lug them together, and will use a ladder-style construction. They will sit on two footings of either concrete or timber - I have yet to decide.

Thanks in advance!

John

 

[KiotiJason]

I'll be watching this thread as I have to do exactly the same thing. Do you have a chainsaw mill?
At this stage I'm planning two concrete footings either side with reo bar/ or threaded bar that will take the bearers, probably 3 depending on the thickness. Then I'll run with 3"x 8" hardwood sleepers with one run long ways down each top edge to stop any of the deck timbers twisting and to give the tyres something to bump against if they run off course. ( stop them from going off the side of page bridge).
That's what I'm think of at least, but interested to see what suggestions you get.

 

[Soundguy]

have you considered a box culvert? ( it's not like regular squash pipe..e tc.. )

 

[NS Gearhead]

I was going to do the same before I sold my Jeep (5,200lbs), so I asked my engineer buddy, he said 4-2X8s per beam would be enough for a 12' span. Assuming your truck is prob 50% more weight so if it were me 5-2x10s or 4-2x12s would be what I'd do.

I ended up building one for the fourwheeler using 3-2x8s per beam... it still may see a Willies or small buggies. I'm sure it could take 4,000lbs.

 

[Streetcar]

Several questions
What is span , there is 50 percent difference from two to three meters
What type of lumber will be used
To prevent rotation of beams , they will need to be braced
What is the heaviest vehicle to cross bridge
What type of foundation will be used
Have much flow is in creek,
What damage will occur if creek is blocked with debris at

 

[s219]

Without knowing the wood characteristics, we can assume typical softwood lumber and be conservative on the fiber bending stress. For a 10' span, each 2x10 can handle 1300 lbs, while each 2x12 can handle 1900 lbs. I'd probably put a 2X factor of safety to err on the side of caution. Be careful to select good boards, as knots or defects can seriously reduce the wood's capability as a beam.

Carriage bolts are not usually rated for structural use. Use regular bolts and washers instead.

 

[Rustyiron]

:welcome:
A quick thought for you're beams, good condition RR ties installed on the footings with the wide dimension vertically @ maybe 12" centers with 2 of them at about 80" (or the track of your truck). Deck with p.t. lumber.

 

[bcp]

Timber bridge plans:

Timber Bridges

Bruce

 

[Streetcar]

Ns gearhead
How are your boards attached at the end of the span?
As you drive a heavier vehicle across bridge , it appears the deck would fail before the beams would

Nice bridge for a four wheeler

 

[ace10]

I was going to do the same before I sold my Jeep (5,200lbs), so I asked my engineer buddy, he said 4-2X8s per beam would be enough for a 12' span. Assuming your truck is prob 50% more weight so if it were me 5-2x10s or 4-2x12s would be what I'd do.

I ended up building one for the fourwheeler using 3-2x8s per beam... it still may see a Willies or small buggies. I'm sure it could take 4,000lbs.

I'm not an engineer, but I have to question the soundness of that design. Both the beam layout and the manner in which is the secured to the banks.