Stress-strain models for normal and high strength confined concrete: Test and comparison of literature models reliability in reproducing experimental results

The adoption of proper constitutive laws for confined concrete is basic for seismic assessment of new and existing reinforced concrete civil structures. The deformation capacity of reinforced concrete (RC) columns subjected to axially centred and eccentric loads depends on the effectiveness confinement action. A proper assignment of the stress-strain laws for concrete allows obtaining an adequate definition of the ductility of the cross-sections and correctly identifying mechanical nonlinearities in computational models. Several studies concerning the behaviour of confined concrete have been carried out, highlighting the role of different geometrical and mechanical parameters to the overall response of RC members in compression. In this frame, the primary aim of this paper is to discuss the reliability of the stress-strain concrete models for concrete subjected to confining stresses in the cases of normal strength concrete (NSC), and high strength concrete (HSC). A selected review of the most popular models for confined concrete available in the literature is presented and discussed together with the respective analytical formulations. Furthermore, a discussion on their reliability is carried out by comparing results coming from the implementation of each model and comparing analytical predictions with experimental data available in the literature.