Ductility of confined reinforced concrete columns with welded reinforcement grids

Concepts in ductile design have led to an increased interest in understanding the role of confinement in improving the seismic performance of reinforced concrete members. Confinement models have been developed by numerous researchers to describe the stress-strain behavior of concrete as a function of certain key parameters that are related to the amount and type of transverse reinforcement. Accurate constitutive models of confined concrete are necessary for use in a computer-based program developed for analysis of reinforced concrete columns subjected to a combination of flexural and axial loadings. This paper presents an analytical approach for computing the moment-curvature response of a section under various load levels by using an idealized stress-strain relationship for concrete confined by welded reinforcement grids. The predictions were then compared with the test results for the corresponding loading levels. Overall, it is found that the predictions for the moments were found to be underestimated, and vice versa for the curvature capacities.