Mechanical analysis of eccentrically loaded SFRC columns reinforced by high-strength rebars: Testing and FE modelling

High-strength rebar (HSR) demonstrates excellent elastic limit and ultimate strength, yet excessive yield strain will lead to deformation incompatibility with concrete. Adding steel fibre can significantly improve the deformation capacity of cement-based materials. Existing experimental studies indicate that increasing the fibre content can improve the ductility and peak strain of RC columns. However, there are limited reports on eccentric loading experiments of steel fibre-reinforced concrete (SFRC) columns with HSR. This study conducted eccentric compression tests on SFRC columns with HSR, examining how eccentricity and fibre content affect the specimens' load-deflection curves. A stress-strain curve for SFRC was developed utilising the gathered data, and a finite element (FE) modelling method for eccentrically loaded SFRC columns with HSR was formed. Finally, numerical calculation models for the moment-force (M-N) and load-deflection curves were established based on the new stress-strain curve. The findings indicate that increasing the fibre content can improve the section curvature and strain of HSRs when the columns with varying eccentricities fail. The effect reaches its maximum at the balanced failure point. Replacing normal-strength rebars with HSRs can enhance the bearing performance of SFRC specimens with large eccentric distances. However, when the eccentric distance is small, the steel bars do not yield at peak load, so increasing rebar strength does not improve bearing performance.