Behavior of circular reinforced concrete columns strengthened with corrugated steel sheets and high-performance concrete

Reinforced concrete (RC) columns are frequently strengthened due to the damage caused by environmental exposure, changes in loading conditions, or seismic upgrading. This paper presents experimental and numerical investigations into the behavior of circular RC columns strengthened using galvanized corrugated steel sheets (GCSS) filled with concrete under eccentric and concentric loads. The effects of the loading condition, the types of concrete used to fill the void, and the existence of additional longitudinal steel bars on structural behavior are examined. The types of concrete include normal concrete, engineered cementitious composite (ECC), ultra-highperformance ECC (UHPECC), and high-strength grout (GR). Test results show that the proposed strengthening technique significantly improves the performance of RC columns. The elastic stiffness and energy absorption of the strengthened columns increase by about 98 %, and 123 %, respectively when compared to those of the control column under concentric loading. Under eccentric loading, the ductility of columns with highperformance concrete (HPC) is better than that of other columns. Moreover, the type of concrete has a remarkable effect on structural behavior. The grout-filled GCSS columns have a higher axial load, ductility, energy absorption, and elastic stiffness than columns constructed with other types of concrete. The finite element (FE) model developed by using ABAQUS is shown to simulate well the experimentally measured responses of concrete-filled composite columns.