Efficiency of GFRP reinforcement in concrete columns having hybrid fibres: experiments and finite element analysis

This investigation explores the structural performance of glass-fibre-reinforced polymer (GFRP)-reinforced concrete columns incorporating hybrid fibres (GHFRC columns) under different loading conditions. The hybrid-fibre-reinforced concrete consisted of two kinds of fibres (steel and polypropylene). A total of nine GHFRC specimens with a diameter of 250 mm and a height of 1150 mm were fabricated and tested to failure. A three-dimensional finite element model (FEM) was developed for the GHFRC specimens using ABAQUS 6.14. The definition of hybrid-fibre-reinforced concrete was performed using an improved concrete damaged plasticity model and the definition of GFRP material was performed by using a linear elastic model. The test results revealed that the ductility of GHFRC columns was improved with the reduction in the ligature spacing. The column eccentricity showed higher ductility indices than concentric columns. The loading eccentricity resulted in a substantial decrease in the axial strength of GHFRC columns. The close correlation between tests and FEM results validates the applicability of FEM. A mathematical model was suggested for predicting the axial strength of GHFRC specimens by taking into account the axial influence of GFRP bars and the confining influence of GFRP ties.