Cyclic Behavior of High-Strength Fiber-Reinforced Concrete Columns under High Axial Loading Level

Analytical and experimental studies of the lateral cyclic behavior of high-strength steel fiber-reinforced concrete (SFRC) columns under a high axial loading level are presented. The confinement efficiency was quantified based on the toughness ratio (TR) instead of column nominal axial strength. One hundred and ten column test results were collected to obtain the relationship between the minimum TR value and confinement parameters. Lateral cyclic tests on three high-strength SFRC columns under high axial compression loading were conducted to verify the confinement efficiency calculated using the TR equation. The use of steel fibers in high strength reinforced concrete (RC) columns improved their confinement efficiency, strength, and ductility, particularly for columns that failed to comply with confinement required by ACI 318-14. The hysteretic loops obtained from experimental results were compared with those obtained from numerical modeling. The use of TR for calculating the equivalent confinement of SFRC columns confined by transverse reinforcement is acceptable.