Seismic Behavior of Concrete Columns Reinforced with BFRP, GFRP, Steel, and Hybrid Steel–FRP Reinforcement

Abstract

Steel-reinforced concrete (RC) columns typically exhibit significant residual displacements and low postyield stiffness when subjected to seismic loads, which may complicate subsequent repairs. This paper investigated the effects of different reinforcement methods on the seismic performance of concrete columns by using glass fiber–reinforced polymer (GFRP) and basalt fiber–reinforced polymer (BFRP) bars. Five samples were subjected to low-cycle horizontal loading tests to compare the corresponding seismic performance indices. The results showed that fully FRP-reinforced concrete columns had a lower energy dissipation capacity and ductility coefficient than RC columns but had other clear advantages in terms of ultimate displacement and a postyield stiffness increase by 100%. Compared to RC columns, the concrete columns with half FRP bars exhibited comparable energy dissipation, greater ultimate displacements and ductility coefficients, and a 60% increase in postyield stiffness. Incorporating FRP bars significantly reduced the residual deformation of FRP-reinforced concrete columns compared to RC columns under the same loading cycle, enabling structural repairs and continued use after an earthquake. During the 2008 Wenchuan earthquake, many traditional reinforced concrete structures were severely damaged, causing significant economic losses and threatening lives and property. Related investigations verified that the deformation of reinforced concrete columns was the most serious under the same displacement level, and adding fiber-reinforced polymer materials greatly reduced the deformation of the concrete columns, which can improve the reparability of the structure after an earthquake. Additionally, the peak load-carrying capacity of fiber-reinforced polymer materials is similar to that of reinforced concrete columns, giving the former a certain application value. In the coastal areas of traditional reinforced concrete structures, because of corrosion, which leads to a significant reduction in the service life of the environment, it is proposed that the introduction of fiber-reinforced polymer materials with excellent corrosion resistance will largely improve the service life of the corrosive environment of the components while ensuring similar seismic performance.