I have a white oak beam 6x6 [exactly] ten ft long. How much weight can it support if lifted on the beam ends?

Answer 1

Ok - this question is a bit confusing on the exact loading configuration. I believe you will put weight on each end of the beam and lift it in the center. If so, the amount of weight it can lift is dependent on the allowable bending stress of oak. Typically this is about 1,500 psi. So, the solution is as follows:


1. The maximum weight on each end = P
2. The bending moment (M) = P x 60"
3. The Section Modulus of the beam, S = [(b)(d^2)]/6 = (6*36)/6 = 36 cubic inches
4. The Allowable Bending Moment = The allowable bending stress (1500psi) x the Section Modulus of the beam (S) or = (1500lb/in^2) x (36in^3) = 54,000 lb-in
5. 54,000 = P x 60"
6. P = 900 lbs

So the answer to your question is that a beam as you described would be adequate to lift 900lbs on each end (1,800 lb total) assuming the lift is at the center of the beam.

Or you could put 1,800lb at the center of your beam as long at the end supports were able to hold 900lbs.

Hope this helps.

Answer 2

Weight Of White Oak

Answer 3

Careful about wood section dimensions. Typically a 6 x 6 wood member actually is 5.5 x 5.5., thus the calc above would be reduced to 77% of what was said. 5.5^3/6 = 27.73 in^3, which is 77% of 36 in^3.

Thus the 900, 1800 lb loads would be reduced to 693 & 1386 lbs.