This paper assesses the seismic response of large circular concrete columns internally confined with glass fiber–reinforced polymer (GFRP) spirals. The experimental program included testing of eight 508-mm-diameter columns reinforced with GFRP spirals and steel longitudinal bars under simulated earthquake loading. Shear–deflection, moment–curvature responses, and various ductility parameters were used to evaluate the performance of the columns. The results showed that the GFRP spirals provided effective confinement to the concrete core until the rupture of spirals at least two locations, corresponding to a strain several times larger than the steel yield strain. GFRP spirals were found to provide increasing confining pressure to the large column core with increased deformations, even more efficiently than comparably smaller 356-mm-diameter columns from a prior study. All the columns satisfied the ductility requirements of the North American codes.