고체역학 (Gere) — Stresses in Beams (Advanced Topics): Problem 6.9-4

6.9-4 The cross section of an unbalanced wide-flange beam is shown in the figure. Derive the following formula for the distance \( e \) from the centerline of the web to the shear center \( S \): \[ e = \frac{3 t_f (b_2^2 - b_1^2)}{h t_w + 6 t_f (b_1 + b_2)} \] Also, check the formula for the special cases of a channel section (\( b_1 = 0 \) and \( b_2 = b \)) and a doubly symmetric beam (\( b_1 = b_2 = b/2 \)).