ABSTRACT
Abstract The cohesive model predicts reasonably well the structural response of concrete specimens of different sizes and geometries, notched and unnotched. An experimental program was set up, where load-displacement curves were measured in notched and unnotched beams and in wedge-splitting specimens. Experimental results agree quite well with numerical predictions based on a simple cohesive model with bilinear softening. The four parameters needed were obtained by using the general bilinear fitting procedure proposed by the authors. Maximum loads were compared with Jenq-Shah's two parameter model and Bazant's model based on the size effect law. Predictions of these models are similar to the cohesive model, although the latter is unable to predict the strength of unnotched samples. Keywords: Concrete, fracture, crack, cohesive crack model, brittleness, size-effect. 1 Introduction It is well known that concrete structures become brittle as their size increases. As an example, in unnotched beams the modulus of rupture decreases as the beam size increases and the same happens for the maximum nominal tensile stress of a series of homothetic notched beams.
