Simulation of the Influence of the Confinement, Until Fracture, on the Shear Stiffness of the Reinforced or Prestressed Concrete

AbstractAn analytical model is presented for predicting complete shear load-deformation response of reinforced or prestressed concrete sections taking into account the concrete confinement. This model is based on the equilibrium, compatibility equations and stress-strain relationships which are formulated in term of average stresses and average strains. According to the assumption of smeared cracks. This model is able to analyze sections having unusual forms or reinforcing details, loaded in combined bending, axial load and shear. In the case of the confined concrete, a stress-strain relation of confined concrete is proposed. In this case, for the purpose of investigating confinement effect, an effectively confined ratio was introduced and the effects according to concrete compressive strength. Predictions of the model are compared with several calculated unconfined reinforced or prestressed beams and are shown to estimate the effect of the confinement on the shear stiffness of the sections in the case of the elastic linear domain, after concrete cracking and after reinforcement yielding