Question

Two steel columns P (Length L and yield strength $f_y$=250 MPa) and Q (length 2L and yield strength $f_y$=500 MPa) have the same cross-sections and end-conditions. The ratio of buckling load of column P to that of column Q is:

• A. 0.5
• B. 1.0
• C. 2.0
• D. 4.0

Answer 1

The correct option is D 4.0

Buckling load as per Euler's method is
$=\frac{{\pi }^{2}EI}{L^2}$
As no information regarding cross-sectional area is given, ratio of buckling load
$\Rightarrow \frac{P_P}{P_Q}=\left(\frac{L_Q^2}{L_P^2}\right)={\left(\frac{2L}{L}\right)}^2=4$