Behavior of GFRP Sheet Wrapped Rectangular RC Column Under Axial Loading

Abstract Over the past few decades, the deterioration of the reinforced concrete (RC) infrastructure has been rapid. There is an urgent need to develop the most cost-effective and efficient methods for repairing or replacing existing RC structures. The aim of this research was to gain an understanding of the axial response of RC rectangular columns with external bonded glass fiber reinforced polymer (GFRP) sheets. A total of 12 rectangular columns were constructed and tested using an axial compression test method. The columns were divided into three groups; three control columns, and three groups of GFRP wrap types (1-layer, 2-layer and 3-layer). The experimental results demonstrated that the addition of GFRP to the columns significantly improved their strength and ductility compared with the control columns. Furthermore, this study shows that the effect of adding layers of GFRP wrap to the rectangular columns is not linear. Specifically, the optimal configuration for improving both the axial loading capacity, as well as ductility of the rectangular columns, is using 2 layers of GFRP wrapping, which provided an 18.15% increase in the ultimate loading capacity of the GFRP wrapped column compared to the control column. The ultimate load of columns wrapped with 1 layer or with 3 layers of GFRP increased by 6.25% and 1.35%, respectively. The failure mode of controlled columns is typically dominated by a brittle concrete crush; conversely, the failure mode of GFRP-wrapped columns is often ductile due to GFRP rupture. The two-layer GFRP wrap configuration was found to be the best balance of structural performance and cost, and that the additional layers of GFRP wrap confer diminishing returns.