A numerical general-purpose confinement model for non-linear analysis of R/C members

A numerical general-purpose confinement model implemented in an open source non-linear structural analysis program is presented. Emphasis is placed on the procedure to obtain the envelope curve of confined concrete and on the iterative procedure required to ensure stable results. The numerical model represents an useful tool to account for confinement effects due to different arrangements of transverse reinforcement and/or external strengthening (such as FRP wraps or steel jackets). The paper concludes with some comparisons with experimental tests of reinforced concrete columns showing the ability of the proposed model to reproduce observed behavior.