Keywords: beams (supports); bearing capacity; failure; reinforced concrete; finite element method; loads (forces); shear strength; span-depth ratio; structural analysis.
Describes an investigation into the causes of shear failure of reinforced concrete beams subjected to two-point loading with shear span-to-depth ratios greater than 2.5. The work complements a previous program concerned with the behavior of beams with shear span-to-depth ratios smaller than 2.5. A finite element analysis of beams with various arrangements of stirrups has shown that the predicted behavior is incompatible with the concept of shear capacity of critical sections that forms the basis of current shear design procedures. The results obtained support the view that shear failure is associated with the development of tensile stresses within the compressive zone of the beams and it is found that one of the main causes for the development of such tensile stresses is the failure of the bond between concrete and tension reinforcement.