### Column Design (Part 6)

From Column Design Part 1 to 5, we talked about the formulas to calculate the critical buckling load. This time we're going to use the excel spreadsheet program to help calculate. Let's use the following design problem as an example.

The machine designer would like to calculate the allowable load for his steel column having rectangular cross section. The column has section 80 mm x 30 mm, and 380 mm long. It's proposed to use AISI 1040 hot-rolled steel. The upper end is pinned and the lower end of the column is inserted into a close-fitting socket and is welded securely as can in the picture.

To calculate the critical load for the column we need to do as following.

Solid rectangular section, 80 mm x 30 mm.

The area moment of inertia, I = 1/12 x 80 x 303 = 180000 mm4 -- The least I (for this case, around X-X axis) is used.

The cross sectional area, A = 80 x 30 = 2400 mm2

Then the radius of gyration, r = (180000/2400)1/2 = 8.66 mm

Since the column is pinned at the upper end …

The machine designer would like to calculate the allowable load for his steel column having rectangular cross section. The column has section 80 mm x 30 mm, and 380 mm long. It's proposed to use AISI 1040 hot-rolled steel. The upper end is pinned and the lower end of the column is inserted into a close-fitting socket and is welded securely as can in the picture.

To calculate the critical load for the column we need to do as following.

Solid rectangular section, 80 mm x 30 mm.

The area moment of inertia, I = 1/12 x 80 x 303 = 180000 mm4 -- The least I (for this case, around X-X axis) is used.

The cross sectional area, A = 80 x 30 = 2400 mm2

Then the radius of gyration, r = (180000/2400)1/2 = 8.66 mm

Since the column is pinned at the upper end …