고체역학 (Beer) — Shearing Stresses in Beams: Problem 6.78

6.77 and 6.78 A thin-walled beam of uniform thickness has the cross section shown. Determine the dimension $b$ for which the shear center $O$ of the cross section is located at the point indicated. [Image P6.78 shows a thin-walled section with the following segments and dimensions: - A top vertical segment $AB$ of length $b$. - A horizontal segment $BD$ of length 2 in. - A central vertical segment $DE$ of length 3 in. - A horizontal segment $EF$ of length 2 in. - A bottom vertical segment $FG$ of length $b$. - Segments $AB$ and $FG$ lie on the same vertical line. - Segment $DE$ lies on a parallel vertical line 2 in. to the left. - The shear center $O$ is indicated at the midpoint of segment $DE$.]