Is there any effect for longitudinal bottom bars to shear stress near support on beam?explain

that depends on why the rebar is needed, but when it is near a support beam the beam will have more stiffness and work as a the rebar for the shear , so the longitudinal bars will not do a lot of work.

after the crack caused by shear stresses yes , before that no ,  because this bottom bars doesn't resist shear stresses, the stirrups do , so we must strengthen the stirrups directly after the support to resist shear stress because the zone after support is the maximum shear zone