Structural behavior of mega steel-reinforced high-strength concrete rectangular columns under axial compression

Abstract

To meet the requirements of practical engineering, mega steel-reinforced concrete (SRC) columns have been used in super high-rise buildings in recent years. Previous studies on SRC columns primarily focused on simple H-shaped and cruciform steel sections; insufficient attention was paid to mega columns, which are frequently designed with complex steel sections and high-strength concrete. In this study, four 1/6 scaled mega steel-reinforced high-strength concrete (SRHC) rectangular columns with cross-sectional dimensions of 700 mm × 565 mm and various steel ratios and concrete strengths were tested under one-way repeated compression to examine the damage evolution, load-axial deformation response, axial bearing capacity, ductility, stiffness degradation, strain development, restoration, and energy dissipation capacity. The test results indicated that increasing the steel ratio effectively alleviated crack widening and concrete spalling and advanced the bearing capacity, ductility, stiffness, restoration, and energy dissipation capacity. With an increase in concrete strength, the peak load, stiffness, restoration capacity in the elastic-plastic stage, and the energy dissipation capacity in the elastic stage improved, whereas the ductility was sharply impaired, resulting in more abrupt damage. Three provisions were examined to calculate the bearing capacity with conservative estimation. Hence, a theoretical model considering the confinement from the stirrups and steel sections was presented to predict the axial strength with a desirable accuracy. Furthermore, a finite element model was developed to perform the damage evolution and parametric study.