Axial compressive behavior of GFRP-timber-reinforced concrete composite columns

This paper investigated the compressive behavior of a novel glass fiber reinforced polymer (GFRP)-timber-reinforced concrete composite column (GTRC column), which consisted of reinforced concrete with an outer GFRP laminate and a paulownia timber core. The axial compression tests were performed on 13 specimens to validate the effects of various timber core diameters, slenderness ratios, and GFRP laminate layers/angles on the mechanical behaviors. Test results indicated that with the increase in the timber core diameter, the ductility and energy dissipation ability of the composite column increased by 52.6% and 21.6%, respectively, whereas the ultimate load-bearing capacity and initial stiffness showed a slight decrease. In addition, the GFRP laminate considerably improved the ultimate load-bearing capacity, stiffness, ductility and energy dissipation capability by 212.1%, 26.6%, 64.3% and 3820%, accordingly. Moreover, considering the influence of timber core diameter, an ultimate load-bearing capacity adjustment coefficient was proposed. Finally, a formula was established based on the force equilibrium and superposition for predicting the axial bearing capacity of the GTRC columns.