Calculating loads on oak beam for ditch crossing
Calculating loads on oak beam for ditch crossing
(OP)
I am proposing to construct a temporary crossing across a wide ditch using 12" x 12" oak timbers. Four 20' long timbers are bolted together, similar to a crane mat. I am proposing to place a set of them from top of bank to top of bank to form a 8' wide deck. The load will be a 35,000 lbs 3 axle earth moving vehicle. How would I calculate if the timbers would hold up to this type of loading? Also, what are some important factors I would need to consider?
Thank you in advance.
Thank you in advance.






RE: Calculating loads on oak beam for ditch crossing
On another note, 20' long 12"x12" Oak sounds like a nice chunk of timber...seems like a waste to just drive over them.
RE: Calculating loads on oak beam for ditch crossing
The span of the opening is approximately 12', with 4' of both ends supported by earth. These supporting areas will need analysis as well, but I'm not concerned about those at the moment. Could I just apply a point load mid-span to be conservative? Also, do you have any suggestions on where I could look to see allowable stresses on timbers?
Thanks CANPRO.
RE: Calculating loads on oak beam for ditch crossing
Yes, for bending. No, for shear - apply the point load adjacent to one of the (assumed) supports. Be certain to carefully select both the value of the point load and the number of timbers that it is applied to. This approach is probably too conservative.
http://www.forestryforum.com/members/donp/Fblist.h...
Without details on the load (wheel base, tire width, weight distribution, etc.) its not possible to provide more than general (somewhat obscure) answers, such as those above.
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RE: Calculating loads on oak beam for ditch crossing
RE: Calculating loads on oak beam for ditch crossing
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: Calculating loads on oak beam for ditch crossing
RE: Calculating loads on oak beam for ditch crossing
Bridge Video
RE: Calculating loads on oak beam for ditch crossing
RE: Calculating loads on oak beam for ditch crossing
Thaidavid
RE: Calculating loads on oak beam for ditch crossing
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.