Structural performance of Eccentrically loaded GFRP Reinforced concrete columns

This paper explores the behavior of GFRP and steel reinforced concrete columns when subjected to eccentrically axial loads. Six columns of 150*150 mm cross section were tested. Four of them had GFRP reinforcement and two had steel reinforcement. The concrete strength of the GFRP reinforced columns was either 24.73 MPa or 38.35 MPa while for the steel reinforced columns it was 24.73 MPa. The eccentricity was either 50 mm or 25 mm and the tie spacing was either 80 mm or 130 mm. Large longitudinal deformations were recorded for columns with GFRP reinforcement and for columns with large tie spacings. However, tie spacing had no notable effect on the maximum lateral deflection and ductility of GFRP columns of this research. The average maximum stress was about 60% of the concrete compressive strength for columns with initial eccentricity of 50 mm. GFRP bars recorded higher strains than steel bars and these strains were larger when the tie spacing was large. The increase in the strength of the concrete was associated with reduction in the GFRP bar strain. Two interaction diagrams were plotted for the columns and they present lower bound to the obtained experimental results.