COMPRESSIVE BEHAVIOR OF CONCRETE - PHYSICAL-MECHANISMS AND MODELING

This paper seeks for a better understanding of the failure mechanisms of concrete in compression and explores the possibilities of incorpora ting these physical mechanisms in the computational modeling of concre te behavior. In the first half, the standard compression test is revis ited. It is found that failure of concrete in compression can be regar ded as the sequence of a two-stage crack mechanism. First, cracks open parallel to the direction of loading, leading to the formation of sma ll columns in the material. Second, the bending of these small columns due to both the heterogeneity of the material and the friction on the lateral edges of the small columns (friction at the lips of the verti cal cracks) lead to the formation of oblique cracks (with respect to t he direction of loading). The latter merge to form oblique slippage pl anes and result in failure. In the second half, these physical mechani sms are explored from a modeling point of view; a probabilistic numeri cal model is proposed that accounts for the initial heterogeneity of t he material, the random creation of geometrical discontinuities (i.e., cracks), and the mechanisms of friction on the crack edges. Several n umerical simulations show that this modeling captures well the physica l mechanisms analyzed.