Experimental and Numerical Investigation on the Behavior of Eccentrically Loaded Hybrid Steel and GFRP RC Columns

This study presents experimental and numerical investigation of the behavior and failure modes of concrete column reinforced by hybrid steel and glass fiber-reinforced polymer (GFRP) bars and subjected to eccentric loads. Twelve reinforced concrete (RC) columns with cross-sectional dimensions of 135 × 135 mm and total length of 1150 mm were considered in the experimental tests. Three of the column specimens were longitudinally reinforced with steel bars, and three columns were reinforced with GFRP bars, while the remaining six columns were reinforced with steel and GFRP bars. All RC columns were subjected to axial compressive loads at five different eccentricity ratios (e/h) ranging from 0 to 1. One additional hybrid RC column specimen was reinforced with a different configuration of steel and GFRP bars and axially compressed at an eccentricity ratio of 0.5. The behavior of the tested RC columns was investigated in terms of load–displacement curves, strain distribution, crack patterns, and failure modes. Experimental test results showed that the ultimate load capacity of eccentrically loaded hybrid RC columns increased compared with that of GFRP or steel RC columns. Also, this study proposes and validates a numerical model to simulate the behavior of the hybrid RC columns considered in the experimental tests. The validated numerical model was used to investigate the effects of several parameters on the response of the hybrid RC columns which have not been covered in experimental programs. Numerical simulation results showed that at high eccentricity ratios (i.e., > 1.5), the ultimate load capacity of the hybrid RC column is higher than that in the GFRP and steel RC columns.