CONFINEMENT MODEL FOR AXIALLY LOADED CONCRETE CONFINED BY CIRCULAR FIBER-REINFORCED POLYMER TUBES. DISCUSSION AND CLOSURE

A discussion of an earlier paper with the aforementioned title, by A.Z. Fam and S.H. Rizkalla, published in this journal (Volume 98, Number 4, July-August 2001), is presented. The discusser raises a number of points relating to the authors' establishment of a second-order polynomial regression for the average lateral-axial strain curves of concrete cylinders tested by Gardner (1969), and believes that the analytical expression for the constant C used in their work does not reflect well the actual behavior of confined concrete cylinders where concrete dilation is delayed due to the action of increased radial pressure. In closure, the authors thank the discusser for his critical review and expand, in more detail, on the modeling of Poisson's ratio of concrete under different confinement levels.