Stress-strain model of FRP confined concrete under cyclic loading

A stress-strain model is proposed for fiber reinforced polymer (FRP) confined concrete subjected to cyclic compression. This model employs an existing monotonic stress-strain relationship as the envelope curve. The cyclic load paths are formed by using a new and simple algebraic function. Concrete strength and confinement stiffness ratio are selected as the main factors that govern the parameters of the unloading and reloading paths. Available experimental results are used to evaluate the model parameters. The model uses more appropriate mathematical forms and includes significant factors ignored previously by others which makes it not only more rational and accurate but also simpler than other existing models reported in the literature.