Experimental investigation and strength modeling of CFRP-confined concrete rectangular prisms under axial monotonic compression

The effectiveness of an FRP jacket for a rectangular concrete column depends mainly on the edge sharpness and aspect ratio of its cross-section. This is because the effective confined area of cross-section will change with the variation of these parameters. In this paper results of an experimental study on the monotonic behavior of CFRP-confined concrete rectangular prisms are presented and the effects of simultaneous changes of aspect ratio and edge sharpness on this behavior are investigated. Other variable which is considered in this study is the unconfined concrete strength. Also the experimental results are compared with the existing models for this type of specimens. The findings of the present study indicate that for both the square and rectangular specimens the strength of confined concrete increases almost linearly with the decrease of edge sharpness. Results also demonstrated that the strength gain of specimens with higher aspect ratios, are much smaller than those of square specimens. The comparison between the experimental results and existing stress–strain models shows that, still there are some deficiencies in the models and further research is required to develop a more accurate stress–strain model for rectangular columns confined by FRP composites.