Modelling of dilation of concrete and its effect in triaxial compression

This paper deals with the modelling of the dilation characteristics of concrete in compression. Triaxial stress states, which are usually activated by prevention of dilation, often govern the load resistance of concrete structures. Therefore, a realistic description of the dilation characteristics of concrete is important. The influence of the dilation characteristics of concrete on the behaviour of actively and passively confined structures was studied. A plasticity approach proposed by Grassl et al. (Int. J. Solid Struct. 39 (2002) 5205) was used to study representative examples of concrete cylinders confined with steel and carbon fibre-reinforced polymers (CFRP). The plasticity model used combines an isotropic hardening law, based on the plastic volumetric strain as hardening parameter, with a non-associated flow rule and a yield surface based on a three-parameter failure criterion proposed by Menetrey and Willam (ACI Struct. J. 92 (1995) 311). It is shown that the plasticity model proposed is capable of predicting the response of both steel- and CFRP-confined cylinders. In the case of steel-confined cylinders, the yield strength of the confining steel is reached so early that the dilation has only a small influence. However, the dilation characteristics of concrete have a strong influence on the axial stress-strain response of the CFRP-confined cylinders. (C) 2003 Elsevier B.V. All rights reserved.