$8-46,$ and $8-49($p$465,$ shigley's mechanical engineering

design$)$

$8-46$ The figure shows a cast$-$iron bearing block that is to be bolted to a

steel ceiling joist and is to support a gravity load of $18$ kN $.$ Bolts used are

M$24$ ISO $8\mathrm{.}8$ with coarse threads and with $4\mathrm{.}6-$mm$-$thick steel washers

under the bolt head and nut. The joist flanges are $20$ mm in thickness, and

the dimension $A,$ shown in the figure, is $20$ mm $.$ The modulus of elasticity

of the bearing block is $135$ GPa $.$

$($a$)$ Find the wrench torque required if

the fasteners are lubricated during

assembly and the joint is to be

permanent.

$($b$)$ Determine the factors of safety

guarding against yielding, overload,

and joint separation.