Q: If the flexural reinforcement yields before shear failure, the displacement of the hydraulic jack P2 will be constrained (No further displacement will be allowed)." Is this correct, or will the force be kept constant after the yielding of the reinforcement (over the middle support), as it is schematically shown in the Fig. 5 (b)?

A: Yes this is correct, no further displacements will be allowed. The figure 5 (b) assumes ideal plastic behaviour, but in the experiment the force of loading jack 2 can increase if hardening occurs.