Analytical model for CFRP confined masonry columns subjected to monotonic and cyclic compression

Confinement of masonry columns using fibre reinforced polymer (FRP) composites have displayed to enhance the axial capacity and ductility. Although, mechanisms of FRP confined masonry column (CMC) subjected to monotonic compression loading with various configurations have been investigated and rational design rules were developed, the response of FRP-CMC under cyclic compression is not widely researched. Therefore, this paper presents an analytical stress-strain model for FRP-CMC subjected to cyclic compression based on the experimental data generated through a testing program. The experimental program has been executed in this research by testing twelve masonry columns confined with discontinuous FRP sheets subjected to monotonic and cyclic compression. The masonry columns were assembled with two varieties of masonry bricks and mortars. The data from the testing of discontinuously CMCs and previous experimental program involving twenty-four continuously CMCs were employed to analytically predict the cyclic compression characteristics. The testing results of discontinuously CMCs subjected to axial monotonic and cyclic compression have shown that they are quite different in terms of their strength and deformability compared to continuously CMCs. The discontinuous FRP strengthening columns resulted in strength and ductility increments in the range of 100-150% and 60-80%, respectively. For the analytical model, the envelop curve, plastic strain, stress deteriorations in cycles, unloading and reloading segments of the proposed stress-strain model have been verified against the experimental data. It has been shown that the suggested analytical model is capable of describing the cyclic axial stress-strain characteristics of FRP-CMCs.