The cross$-$section of a rectangular simply supported beam is shown in the figure below, with a span of $8$ m and a uniform static load of $3\mathrm{.}2t\frac{f}{m}($including its own weight$)$ and a uniform live load of $4\mathrm{.}5t\frac{f}{m}.$ A concentrated live load of $4$ tf is carried in the center. The concrete strength of this beam is $280kg\frac{f}{c}{m}^2,$ the yield strength of flexural steel bars is $4200kg\frac{f}{c}{m}^2,$ and the yield strength of shear steel bars is $2800kg\frac{f}{c}{m}^2.$

$($a$)$ What is force Vu at the critical section? $(3\%)$

$($b$)$ The range of no need to configure the shear reinforcement. $(4\%)$

$($c$)$ The range of the minimum shear reinforcement. $(6\%)$

$($d$)$ The distance between the shear bars at a distance of $1\mathrm{.}0$ m from the support. $(6\%)$

$($e$)$ The distance between the shear bars at a distance of $0\mathrm{.}5$ m from the support. $(6\%)$