Investigation of Reinforced Concrete Columns Confined using Glass Fiber-reinforced Polymers

Experimental studies are reported on upgrading the load carrying capacity of reinforced concrete rectangular columns by jacketing with glass fiber reinforced plasic flexible wraps. This article presents results of a comprehensive experimental investigation on the behavior of axially loaded rectangular columns that have been strengthened with glass fiber reinforced polymer (GFRP) wrap. This study is intended to examine several aspects related to the use of GFRP fabrics for strengthening rectangular columns subjected to axial compression. The objectives of the study are as follows: (1) to evaluate the effectiveness of external GFRP strengthening for rectangular concrete columns; (2) to evaluate the effect of the number of GFRP layers on the ultimate strength and ductility of confined concrete; and (3) to evaluate the effect of the aspect ratio of the column on the effectively confined cross section. To cover a wide range of cross-sectional dimension ratios, three aspect ratios (H/B, where H and B are, respectively, the longer and shorter sides of the cross section) are studied: H/B = 1.0, H/B = 1.25, and H/B = 1.66. Specimens with zero, one, and two layers of GFRP wrap are investigated. In total, nine specimens are subjected to axial compression which includes three control specimens. All the test specimens are loaded to failure in axial compression and the behavior of the specimens in the axial and transverse directions is investigated. The confinement provided by GFRP improves both the load carrying capacity and the ductility of the rectangular and square columns. This method of structural rehabilitation is shown to be applicable to rectangular sections.