Question

what does Vcr mean ? how can a beam carry shear force without shear reinforcement

Answer 1

Vcr means the critical shear force i.e it is the amount of shear force in a section beyond which cracks generate in the section.

✓✓ Without shear reinforcement , the beam can carry shear force by Dowel action and aggregate interlocking. When the shear force acting on the bar and the inclined cracks crosses the critical section and the longitudinal reinforcement, the dowel actio i.e deflection of the bar in the direction of crack and aggregate in the beam around the bar try to resist the deflection with interlocking each other (action of aggregate interlocking), by these duel action we shear strength increases, shear reinforcement decreases. Crack width, size of aggregate is highly depends upon concrete strength.