Full-scale and half-scale fibreglass-confined concrete columns for seismic resilience

Steel corrosion is by far the biggest durability issue for many reinforced concrete bridge structures worldwide. The columns in these bridges can be critical, especially for seismic resistance. In this study, glass-fibre-reinforced-polymer bars were investigated as an alternative to steel for sustainable and resilient bridge construction. As lateral reinforcement is more susceptible to corrosion, and structures fully reinforced with fibreglass bars display softer responses with lower shear and flexural capacity, fibreglass spirals and longitudinal steel reinforcement were used in the tested columns. The experimental programme included the design, construction and seismic testing of full-scale (508 mm diameter) and half-scale (356 mm diameter) columns. The other variables investigated were the axial load and the amount and spacing of spirals. For both column sizes, fibreglass spirals provided increasing confining pressure to the concrete core with increased deformations. For the full-scale columns, no adverse size effects were observed in comparison to the half-scale columns. The columns produced large ductility and energy dissipation. Results from selected representative specimens are presented here to establish the feasibility of using fibreglass spirals in circular bridge columns. Resilience can thus be built into new columns through innovative durable fibreglass lateral reinforcement, with similar if not superior behaviour to steel-reinforced columns.