Stress-strain model for concrete under cyclic loading

A hysteretic stress-strain model is developed for unconfined concrete with the intention of providing efficient modelling for the structural behaviour of concrete in seismic regions. The proposed model is based on the findings of previous experimental and analytical studies. The model for concrete subjected to monotonic and cyclic loading comprises four components in compression and tension - an envelope curve (for monotonic and cyclic loading), an unloading curve, a reloading curve and a transition curve. Formulations for partial unloading and partial reloading curves are also presented. The reliability of the proposed constitutive model is investigated for a reinforced concrete member using a non-linear finite-element analysis program. Comparisons with test results showed that the proposed model provides a good fit to a wide range of experimentally established hysteresis loops.