A simply supported rectangular beam, beam section $b=35cm,d=52\mathrm{.}5cm,h=60$ cm $,$ the midpoint of the beam span bears a concentrated design load of $36$ tf $.$ Concrete strength $f{c}^{\text{'}}=210kg\frac{f}{c}{m}^2,$ excluding the weight of the beam, try to find the calculated strength of the maximum concrete shear force in the critical section of the following sub$-$problems. $($Assuming that the tension bar of this beam is $3$D$25,$ its yield strength is $4200kg\frac{f}{c}{m}^2)$

$($a$)$ No axial force $[$use detailed calculation formula$].(10\%)$

$($b$)$ With an axial compressive force of $20tf(5\%)$

$($c$)$ With an axial tension force of $20tf.(5\%)$