Short Column Slenderness Ratio

[mklt]

1. I have a slenderness ration of 23.7 and my material is steel. The appropriate range for steel is 30<Le/k<120 (Structural Steel) what do you do with the equation if the Slenderness Ration is less than 30? Do you use Euler's Formula or Johnson's formula? I can't remember.

2. Schedule 40 Pipe, steel, E=29000 ksi, I=.1947, A=.6685, L=18.1, k=.5397, N=3 Euller's or Johnson's?

 

[rb1957]

1 johnson ... euler for long columns

2 N=? ... i'd use johnson

 

[desertfox]

Hi mklt

I'd use the Rankine-Gordon formula for intermediate struts:-


P = stress allowable* area/(l+a(I/k)^2)

where p = safe load

l = column length

I= second moment area

k= radius of gyration

a = constant= 1/7500 for mild steel

desertfox

 

[mklt]

Desertfox - Thanks so very much for your help with this. I'm not familiar with Rankine-Gordon but I'll look into that.


rb1957 - N=3. (Ground support Equipment. What do you think? Still use Johnson?

 

[desertfox]

Hi mklt

Have a look at this link

http://www.freestudy.co.uk/strength of materials/tutorial 2 3.pdf

your welcome

desertfox

 

[desertfox]

Hi mkit

Are you sure about the slenderness ratio of steel you quoted?
It looks to me as you might not have a strut at all but a straight forward crushing mode with such a small slenderness ratio.

desertfox

 

[desertfox]

Hi again

take a look at this site and scroll to the bottom of the page it gives slenderness ratio's for steel less than 40 are not struts

http://www.efunda.com/formulae/solid_mechanics/columns/intro.cfm

desertfox

 

[mklt]

desertfox,

Thanks again. You've been a great help.

Regards,
mklt (Mike)

 

[desertfox]

Hi mklt

your welcome

 

[Ron]

I agree with desertfox....this isn't a buckling issue...it's a crushing issue or punching issue.