Characterization of Combined Longitudinal and Transverse FRPs for Strengthening Concrete Columns

Abstract

This paper presents the results of a study on the characterization of combined longitudinal near-surface-mounted (NSM) fiber-reinforced polymer (FRP) bars and transverse FRP wraps for strengthening concrete columns. A total of 21 concrete cylinders were prepared, strengthened, and tested to characterize the performance of the strengthening system. Three arrangements of glass FRP (GFRP) bars were mounted in surface grooves, and unidirectional basalt FRP (BFRP) composite was used to wrap the specimens. It was shown that the wrapping system effectively prevented the premature failures of the NSM bars and extended the contribution of the bars from an average of 17.5% in the NSM specimens to an average of 27.7% in the specimens strengthened with the combined NSM and transverse FRPs. An analytical model was also presented to predict the load-strain behavior and the effect of combined axial load and bending moment.