Abstract. Concrete is widely used for many practices in Civil Engineering. Therefore, an understanding of its behavior helps engineers and researchers to perform more accurate and cost-e ective analyses and designs. In this respect, several models have been proposed to predict the behaviors of concrete most of which are satisfactorily accurate. However, by increasing the accuracy of the models, their computational cost increases, too. In this study, a model with the least computational cost is proposed to predict the behaviors of various concretes and con nement conditions. This model does not require any experimental tests to determine its parameters. It was proved to be able to predict the behaviors of various concretes, including Normal-Weight Concrete (NWC) and Light-Weight Concrete (LWC), from other researchers. This model can also be applied to two-and three-dimensional problems. Moreover, the con nement conditions of concretes were considered. The predictions were in good accordance with the experimental results.