Behavior of High-Strength RC Columns Subjected to High-Axial and Cyclic Lateral Loads

This experimental investigation was conducted to examine the behavior and response of high-strength material (HSM) reinforced concrete (RC) columns under combined high-axial and cyclic-increasing lateral loads. All the columns use high-strength concrete (f_c^'' =100 MPa) and high-yield strength steel (f_y=685 MPa and f_y=785 MPa) for both longitudinal and transverse reinforcements. A total of four full-scale HSM columns with amount of transverse reinforcement equal to 100% more than that required by earthquake resistant design provisions of ACI-318 (computed using the actual stress without any limitation) were tested. The key differences among those four columns are the spacing and configuration of transverse reinforcements. Two different constant axial loads, i.e. 60% and 30% of column axial load capacity, were combined with cyclic lateral loads to impose reversed curvatures in the columns. Test results show that columns under 30% of axial load capacity behaved much more ductile and had higher lateral deformational capacity compared to columns under the 60% of axial load capacity. The columns using type A of transverse reinforcement configuration had slightly higher deformational capacity and ductility than columns using type B of transverse reinforcement.