Behaviour of hollow core square reinforced concrete columns wrapped with CFRP with different fibre orientations

Results of testing twelve hollow core square reinforced concrete columns wrapped with Carbon fibre 33 reinforced polymer (CFRP) are presented. The effect of fibre orientation on the performance of specimens 34 under concentric and eccentric loads was investigated. Twelve specimens were divided into four groups with three 36 specimens each. The specimens in the first reference group were unwrapped, while the specimens in the 37 remaining groups were wrapped with CFRP of different wrap combinations of three fibre orientations.The specimens in each group were tested 39 under three eccentricities: 0 (concentric), 25, and 50 mm up to failure. Test results show that all wrap- 40 ping configurations increased both the strength and ductility of hollow core square reinforced concrete 41 columns. However, the increase of compressive strength was marginal. The columns, which were 42 wrapped exclusively with hoop configuration, proved to have the greatest ductility. Axial load-bending 43 moment P- M interaction diagrams of each group were drawn based on the experimental results and 44 compared with theoretical calculations.