Sensitivity in Shear Strength of Longitudinally Reinforced Concrete Beams to Fracture Energy of Concrete

The size effect in shear strength of longitudinally reinforced beams is studied by means of a nonlinear fracture mechanics model. According to the actual theoretical study, structure size should be normalized to an intrinsic length parameter of the concrete. This length parameter is proportional to the fracture energy G//F of the concrete. It is found that the shear strength of a concrete beam may be equally sensitive to G//F as to the tensile strength of the concrete. It is concluded that G//F should be measured during experimental studies of the shear strength of beams and the punching strength of slabs. A simple method for considering the intrinsic length parameter in existing shear strength formulas is proposed.