Design of Steel Fiber-Reinforced High-Strength Concrete- Encased Steel Short Columns and Beams

Abstract

This study explores the possibility of completely replacing traditional steel bar reinforcement by steel fibers in high-strength concrete-encased steel columns, showing potential for ductile structural behavior and reduction in construction time. Compression tests with varying eccentricities of loading were conducted on nine concrete-encased steel short columns containing different dosages of hooked-end steel fibers. The specimens also contained small straight steel fibers to control the propagation of microcracks. In addition, three beams were tested under four-point bending to obtain the ultimate moment-carrying capacity of the composite section under pure bending. The test results were used to plot the axial load-bending moment (N-M) interaction diagram of steel fiber-reinforced high-strength concrete-encased steel columns without traditional reinforcement. Two analytical approaches were proposed to predict the N-M interaction diagram, and their accuracy was verified against the test results. Parametric studies show that the load-carrying capacities of concrete-encased steel columns with steel fibers only are comparable to those with traditional steel bar reinforcement. The research demonstrated that the replacement of traditional steel bar reinforcement by steel fibers shows promise for application in high-strength concrete-encased steel columns.