Column loaded with a distributed axial load. 3

[BR0]

I have a wood column that is loaded with a vertical distributed load. Intuitively it seems that his would have a lesser impact to buckling than a column loaded at the top. I have looked at Roark - Formulas for Stress and Strain and haven't seen any way to account for this.

Maybe my intuition is off, but if anyone knows if this can be taken advantage of, I'd really appreciate it.

Thanks, Bob

 

[CANPRO]

Your intuition is not off. The buckling capacity of a uniformly loaded column can be found in Theory of Elastic Stability by Timoshenko and Gere.

 

[BR0]

Hi Canpro,
Awesome reference, I should have pulled that book down, but it hasn't had much use lately. I have the 1936 version, prior to Gere's involvement.

 

[Hokie93]

The second edition of Theory of Elastic Stability gives the topic additional treatment. The factor is essentially equal to 2.0 for a pinned-pinned column. You might want to consider using something less than 2.0 (say, 1.5) given that your column is imperfect. You could also use Roark's Formulas for Stress and Strain and, conservatively, split your axial load between the top and mid-height of the column.

 

[Agent666]

Also read up on elastic critical buckling analyses, most software packages can do them these days and they are very useful for unusual loading or restraint conditions.

 

[Tomfh]

Assuming load at the top is conservative.

A column buckles when the work required to buckle equals that required to further compress the column by the same amount, and it takes twice as much load do the same amount of work (i.e. compress the column by a given amount) if the axial load is a UDL.

 

[BR0]

Thanks everyone. Comments have been great.