Behavior of concrete prisms confined with FRP composites under axial cyclic compression

Seismic retrofit of concrete columns by means of fiber reinforced polymer (FRP) composites is a well known method for enhancing their strength and ductility. For proper designing of rectangular concrete columns confined with FRP composites, a good understanding of the stress–strain behavior of FRP-confined concrete prism under axial cyclic compression is necessary. In this article, results from a series of axial cyclic compression tests on 10 square prismatic specimens are presented. Specimens were subjected to various cyclic loading patterns to examine different aspects of cyclic behavior of FRP-confined concrete prisms. Results of tests show that the envelope curve of the cyclic stress–strain curve of FRP-confined concrete prisms is approximately the same as the stress–strain curve for the same concrete under monotonic loading. The study also indicates other important results such as, linearity of relationship between the plastic strain and the envelope unloading strain, increase of the axial strain in the early stage of envelope unloading paths, and the cumulative effect of loading history on the plastic strain and stress deterioration.