Problem 9: For the box column of question 8, use the allowable design method to determine the allowable centric load.

Solution: The factor of safety from the previous problem cannot be used, since the F.S. is built into the allowable design method. Since steel has a yield strength of 250 MPa, using equation 10.42...

Using the moment of inertia found in Problem 8, the radius of gyration is

Therefore, the slenderness ratio is L/r = 2 m/0.0588 = 33.996. Since this is less than C_c, I use equations 10.44 and 10.45:

Compare this answer with that for question 8.