Shear strength of beams with loads near the supports

In reinforced concrete beams subjected to concentrated loads, the shear resisted increases considerably as the loads approach to the support. There is not a consensus in the current codes of practice about any simple design formulation which adequately considers this phenomenon. A mechanical model has been developed at the Polytechnic University of Barcelona, which predicts the shear strength of beams. The mo del is originally applicable to slender beams (a/d >2.0 - 2.5), and is under consideration for adoption into the Eurocodes. The model deals with shear - flexure failure, in which flexural cracks develop inclined through the web and stabilized near the neutral axis. Failure is assumed to happen when this flexural crack develops inside the compression chord, subjected to normal and shear stresses, which takes place when the stresses reach the biaxial failure envelope of Kupfer. The model has been extended to ca ses where the loads are applied near the supports. In this case, the Bernoulli assumption (Plane sections remain plane) is no longer valid, and the problem must be faced as a typical discontinuity “D” region, because the dimensions (a/d