wooden bridges

[jdkid]

Hi ya's
i have a prob that i wonder if some of the brains on here can help..ok on our farm there is a bridge made from 8x1's nailed together to make the main beams and the top deck is 4x1-6x1's (i'll have to get the right mersures to do this right)all the boards are stacked on there eage so it should be a lot stronger that a thicker beam..if some one can help i can get more info W X H X L etc etc i want to take a dozer and tractors across it (11 tonne dozer D4 and 7-8 tonne tractor)
catch ya
JD Kid
oh yea what about container (20 x 8)bases for bridge building ???any ideas?

 

[TWINKLE_TOES]

JD

Might be able to help if I understood a little better. If the <font color=blue>8x1's</font color=blue> are 8 inch x 1inch, how many are nailed together, the full width of the bridge? Other stuff that would help is kind of wood, what shape its in, distance between vertical supports. Right off hand it don't look to good for the tractor or the dozer.
Al

 

[rmorgan]

Peter--Although I couldn't begin to advise somebody who drives 400 hp tractors around their property about where they could or couldn't take them, I'd sure be interested in seeing a snap of your bridge--as well as your tractor and your farm! That said, it sure sounds like the tractor might end up "down under" the bridge /w3tcompact/icons/laugh.gif . . .

Rick

 

[woodmills1]

i have some info from state of nh about timber bridges that are built of 2 by stock stood on edge. these bridges are bolted together crossways with iron to draw them together. if yours is nailed 1 by stock i might also be leary of taking the dozer across, though i might try the tractor knowing i had the dozer to rescue it

James "woody" Mills

 

[jdkid]

Hi ya
well the bridge is 20 foot long by 10 foot wide the top is all 4 x 1 's (4 inch by 1 inch) the beams under it are spaced like this 8, 8x1 right on eadge then 58, 8x1 in middle then 8 ,8x1's on the far side prob is where all ya wheels run the main beams are not so even if the beams could hold up the deaking maynot unless i put runners on top of decking.
ok the wood it looks like a harder kind of wood not a fir but i don't realy know
catch ya
JD Kid

 

[TWINKLE_TOES]

That's quite a bridge. I'll see what I can come up with. If you have a rig that you cross safely with now, and know it's weight, measure the midspan deflection with the rig in the center of the bridge. I'm pretty sure there ain't no way I'm going to tell you it's 100% safe. If you were to fall I'm sure I couldn't "catch ya"/w3tcompact/icons/wink.gif

Al

 

[JJT]

JDKID, I designed and built my timberframed house, cutting the frame by hand, (it was an out of control woodworing project). Get me the unsipported span on your bridge, the dimensions on the laminated timbers as well as the type of wood and I'll do the stress analysis for you.

 

[jdkid]

Hi ya
well the unsupported span would be about 17-18 foot the boards are nailed together (stab in the dark there)and wood i don't realy know it dose not look like a fast growing type but not very very fine grain there dose not appare to be many/any knots in it if i had a cam i would get some pics for ya
catch ya
JD Kid

 

[Youare]

I"ve helped build a couple of bridges, one out of wood the other had steel I-beams with a wooden deck. The wooden bridge was over about a 16 foot span, and the steel I-beam bridge was about a 20 foot span.

The wooden bridge has (3) 8-10" diameter hemlock logs where the wheels of a truck would travel and (2) more of the same diameter logs in the middle. There is a 2" thick deck over that and then running the other way another 2" thick 12" wide planked area where the wheel track would be.

I have driven a pick-up loaded with fire wood over the bridge many times, but if I had a dump truck I would not drive it over the bridge loaded.

The steel I-beam bridge was constructed so that a loaded cement truck could pass over it. Which did happen several times. There were two 6X12 I-beams under each wheel track and two 2" decks over that running in opposite directions.

Jd's bridge sounds a little light to be putting all that weight over. If he could shore up underneath it in the middle with some cribbing that would make a world of difference.

Randy

 

[jdkid]

Hi ya
well i do know people have taken spray trucks across it all up bout 3-3.2 tonne 6600-7000Lb and from what i'm told it dose not flex with that wieght ....would not fall far but would start a chain smoking,new dacks,loss of face colour kinda reactiononly bout 4-5 foot above little stream
catch ya
JD Kid