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Section properties of a rectangle and a built-up I-section

Area, second moment of area, elastic modulus and radius of gyration of a rectangle and of a welded I-section. Reference: Mechanics of materials.

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# Rectangle
b_r := 300 mm
h_r := 600 mm
A_r := b_r*h_r = mm^2
I_r := b_r*h_r^3/12 = mm^4
W_r := I_r/(h_r/2) = mm^3
i_r := sqrt(I_r/A_r) = mm

# Welded I-section
b_f := 250 mm
t_f := 20 mm
h_w := 560 mm
t_w := 10 mm
h_s := h_w + 2*t_f = mm
A_I := 2*b_f*t_f + h_w*t_w = mm^2
I_I := b_f*h_s^3/12 - (b_f - t_w)*h_w^3/12 = mm^4
W_I := I_I/(h_s/2) = mm^3
i_I := sqrt(I_I/A_I) = mm

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