Braced column under compressive load

[sukibelle]

Homework Statement

Homework Equations

P = EI pi^2 / Leff radius of gyration: SQRT (I/A), slenderness ratio: Leff/r

The Attempt at a Solution

So I've found Ixx = 240.81 x 10^6 mm^4, Iyy = 71.9 x 10^6 A = 9600 finding the radiuses of gyration rx = 158.38, ry = 86.54
effective length of x-axis : (one end pinned, I'm assuming the buckling = fixeed and do i use the longer length?) 6*0.7 = 4.2
efective length of y: 10*1 (both ends pinned)
I'm not sure about the effective length part, I know I'm meant to find the larger slenderness ratio (which identifies the weaker axis) and then plug that into the P = EI pi^2 / Leff . I don't know how to address a column supported in this way. do I average the lengths or something?

 

[PhanthomJay]

You should use k = 1 as the effective length factor in both cases, where L = 10 for major axis and L = 6 for minor axis. This is due to member rotation at the braced support at the buckling mode. See which controls. Also check your buckling formula the L should be squared, Pcr = pi^2 EI/L^2