$(10$ pts$)$ Problem $4$:

$(2\mathrm{.}5$ pts $)$ i$.$ The maximum stress due to bending occurs:

$($a$)$ at the neutral axis

$($b$)$ at the outermost fiber

$($c$)$ between the neutral axis and the outermost fiber.

$(2\mathrm{.}5$ pts $)$ ii$.$ If the bending moment is increased in a beam, the radius of gyration will:

$($a$)$ increase

$($b$)$ decrease

$($c$)$ stay the same.

$(pts)$ iii. The following shows the floor plans for two steel buildings A and. B$.$ The required. section modulus for joist $(J-1)$ in building B is:

Explain WHY?

$($B$)$

$($a$)$ The same as for building A

$($b$)$ Twice as building A$\text{'}$s

$($c$)$ Three times as building A$\text{'}$s

$($d$)$ Four times as building A$\text{'}$s