FRP Wrapping for RC Columns with Varying Corner Radii

Existing reinforced concrete (RC) columns may be structurally deficient due to variety of reasons such as improper transverse reinforcement, flaws in structural design, insufficient load carrying capacity, etc. Carbon/Glass fibre reinforced polymer (FRP) confinement can be effectively used for strengthening the deficient RC columns. The effectiveness of FRP wrapping for RC columns mainly depend upon corner radius of the specimens as well as number of FRP layers used for the confinement. An attempt has been made hereby to investigate the experimental behaviour of GFRP wrapped small scale square RC columns with varying corner radii. Experimentally evaluated behaviour of GFRP wrapped RC columns is compared with the performance observed for non-wrapped RC columns. 15 RC columns having cross-sectional dimensions 125 mm x 125 mm and length of 1200 mm have been tested under axial compression. Three columns are unwrapped and have been designated as control specimens. Three columns each with corner radius equivalent to cover of 25 mm are wrapped with one and two layers of GFRP, respectively. To avoid a premature rupture of the GFRP composite, remaining six columns with corner radius of 5 mm have been wrapped with one and two layers of GFRP, respectively. GFRP wrapped columns go under higher axial displacement in order to gain higher compressive strength over the control column. The results showed that smoothening of the edges of square cross-section of RC columns play a significant role in delaying the rupture of the FRP composite at the edges. Corner radius equal to concrete cover gives better results in terms of ultimate load carrying capacity than the corner radius less than cover for confined RC columns. (C) 2013 The Authors. Published by Elsevier Ltd.