Viscous Damping and Energy Dissipation of Concrete Columns Reinforced with Hybrid Reinforcement Constituted of Steel Bars and GFRP Spiral and Cross Ties

Steel bars in reinforced concrete structures are prone to corrosion causing loss of strength and energy dissipation capacity of the concrete structures. The problem of corrosion in civil infrastructure has encouraged research in new noncorrosive reinforcements such as glass fiber-reinforced polymer (GFRP) bars. GFRP bars have good corrosion resistance; however, it has a linear elastic stress–strain relationship which affects the energy dissipation capacity of a concrete structure subjected to simulated lateral cyclic loading. The present paper assesses the seismic response of concrete columns reinforced with steel longitudinal bars and confined with GFRP spiral and cross ties. Analytical studies were conducted on four full-scale 400 × 400 mm columns subjected to quasi-static lateral cyclic load. The variable parameters in the study were longitudinal bar size and spacing of GFRP spiral and cross tie. The viscous damping, energy dissipation capacity, and stiffness degradation were used to evaluate the performance of the concrete column. Outcome of this study shows that the energy dissipation capacity improved by reducing the spacing of GFRP spirals and cross ties. Further, the hysteresis viscous damping decreased with increase in the longitudinal bar size. Finally, simplified empirical equations are proposed to estimate viscous damping and energy dissipation capacity for the studied reinforced concrete columns.