Study on Axial Compression Properties of a New Type of Fiber-Reinforced Square Concrete-Filled Steel-Tube Composite Column

Concrete-filled steel-tube (CFST) composite columns have been used in many different types of structures due to their high strength, good ductility, and practical construction advantages; however, the disadvantage of their weak anti-corrosion and fire protection capacity also restricts their use in some specialized engineering projects. In this paper, experimental investigations on the axial compression characteristics of square CFST composite columns with fiber reinforcement were conducted. The failure mechanisms, energy dissipation coefficient, load and strain fluctuations of the columns were analyzed. Meanwhile, the bearing capacity was verified by numerical simulation results. The findings demonstrate that fiber reinforced concrete improves the test columns' bearing capacity and deformation capacity; the steel fibers had more influence on load-bearing capacity, with the same steel content and steel tube thickness, the bearing capacity can be increased by 67.55%. Whereas the polyvinyl alcohol fibers had better improvement in ductility. The fiber-reinforced concrete specimens showed oblique shear failure, whereas the ordinary concrete specimens had poor deformation ability and exhibited crushing failure. The load-carrying capacity was more sensitive to changes in the steel content, With the steel content increasing from 1.56 to 3.04%, the carrying capacity increases by 33.69%.