Compression load post/beam what can it withstand?

[uffe v]

What does the formula for calculating the compressive strength of a pole look like?
I have read somewhere that you can calculate with 30 - 35 kg/cm2. Could that be correct?

If you have a pole with a diameter of 15 cm, then we have an area of 176 cm2.
Then the theoretical strength would be 5 - 6 tons. Could that be correct?

H/Uffe

 

[anaitis]

What is the formula for calculating the compressive strength of a post?
I've read somewhere that you can calculate with 30 – 35 kg/cm2. Could that be correct?

If you have a post with a diameter of 15 cm, then you have an area of 176 cm2.
Then the theoretical strength would be 5 – 6 tons. Could that be correct?

H/Uffe

It depends!
Could be true, but could also be completely wrong.
For a very short cylinder, it could be true.

Among the factors affecting it, you'll find
Length
Attachment conditions
Guidance
Moisture content
Safety class

There are surely more that I can't remember right now.

 

[uffe v]

Absolutely right in what you're saying, but I'm interested in the theoretical strength.

So let's look at a short (2m above ground), completely straight, perfectly anchored at the bottom (1m into the ground to firm foundation), and with the load distributed over the entire surface at the top.

 

[anaitis]

Absolutely right in what you're saying, but I am looking for the theoretical strength.

That is precisely the theoretical strength I was trying to describe.

 

[Bastefallarn]

There are sizing tables for poles here (almost at the bottom of the page):

http://www.traguiden.se/TGtemplates/PageTwoColumn.aspx?id=1465

 

[anaitis]

So let's look at a short (2m above ground), perfectly straight, perfectly fastened at the bottom (1m into the ground to solid foundation) and with the load distributed over the entire top surface.

How about the upper end? Is it free or guided? Fixed?
Wood?

The slenderness ratio, if I calculate with a free top and fixed base in the ground (this is rarely the case though), becomes 2.25 * 200 / (15/4) = 120
This slenderness ratio gives a correction factor of about 0.28
Then the design-bearing capacity will be 0.28 * pi*150*150/4 * 11 (K12, SK1)
which is approximately 54 kN