고체역학 (Gere) — Stresses in Beams (Basic Topics): Problem 5.6-26

5.6-26 The cross section of a rectangular beam having a width $b$ and height $h$ is shown in part a of the figure. For reasons unknown to the beam designer, it is planned to add structural projections of width $b/9$ and height $d$ to the top and bottom of the beam (see part b of the figure). For what values of $d$ is the bending-moment capacity of the beam increased? For what values is it decreased?