Impact performance and damage assessment of GFRP-RC columns at high temperatures: a numerical insight

Fiber-reinforced polymer (FRP) bars have better resistance to corrosion and higher tensile strength than steel bars, thus being a prospective material for concrete structures in marine engineering. However, it is less fire-resistant, and the residual bearing capacity of FRP-reinforced concrete members after the fire needs to be clarified. This study explores the impact resistance of Glass FRP-reinforced concrete (GFRP-RC) columns at high temperatures using finite element models. To assess the accuracy of the model, the simulation results were compared with the test results in terms of fire resistance and impact resistance, respectively. Based on these, the impact behavior of GFRP-RC and steel-RC columns were compared and analyzed. The results show that GFRP-RC columns were more severely damaged by impact loading after high temperatures than steel-RC columns. The peak impact forces of the GFRP-RC columns and steel-RC columns are nearly identical. However, the former has a smaller reaction force and a more significant mid-span displacement. Furthermore, the residual axial bearing capacity of GFRP-RC columns after high temperature and impact loading is significantly reduced compared to steel-RC columns. Exposure to high temperatures takes a more significant proportion in the reduction than impact loading. In addition, a relationship between the damage index (based on residual bearing capacity) and the lateral displacement of the columns after fire and impact loadings was established. In contrast, the corresponding damage classification criteria were determined.