Effect of Corner Radius on Confinement Effectiveness of GFRP and Lateral Ties Confined Polyolefin Fibre Reinforced Concrete Prisms under Monotonic Axial Compression

In testing the fibre-wrapped concrete specimens under compression, the failure of the GFRP wraps is observed at or near a corner in all the specimens, mainly due to stress concentration. This may be expected since the prism's sharp edges are not rounded off. In order to avoid stress concentration, an attempt is made to round off the sharp corners. To further study this problem, this research undertook compressive testing to investigate the effect of the corner radius on the strength and ductility of the FRP confined concrete prisms. This paper reports a series of tests on glass fiber-reinforced polymer (GFRP) confined concrete prisms. A total of twenty-three prisms of size 150 × 150 × 300 mm were tested under the strain control rate of loading. The primary variables in the investigation were the corner radius, transverse jacket, spacing of laterals and volume fraction of the polyolefin fibers. The results show that the smoothening of the edges of a square cross-section plays a significant role in delaying the rupture of the FRP composite at these edges, and the efficiency of the FRP confinement is directly related to the radius of the cross-section edges. Furthermore, it is revealed that the confinement provided by a jacket with rounded corner radius is not only increasing the strength of the concrete prisms, but significant in increasing the ductility of the concrete prisms.