Performance-based Seismic Assessments of Steel Fibre Reinforced Concrete Columns

Abstract This study presents a comprehensive investigation into the seismic performance of steel fibre reinforced concrete (SFRC) columns, aiming to assess their ductility and energy dissipation capacity. A large-scale database consisting of 116 individual tests of flexure-dominated SFRC and plain concrete (PC) columns subjected to cyclic lateral loading is utilized. The research begins by conducting parametric sensitivity analyses and empirical calibration of hysteretic parameters, crucial for accurately modelling the seismic response of reinforced concrete columns. These analyses are performed in accordance with a nonlinear static procedure. Additionally, fragility analyses of both reinforced PC and SFRC columns are conducted, based on their respective lateral drift ratios, with a specific drift ratio defined as the damage limit state. The findings of this work reveal intriguing insights. It is found that the axial load ratio has a comparable effect on the plastic rotations at the yield and ultimate points of PC and SFRC columns. However, it exhibits an entirely opposite effect on the rotation corresponding to the peak lateral load, especially for those with over 0.75% of fibres by volume. This discrepancy suggests that the current seismic design standards for PC columns are not directly applicable to SFRC columns. Furthermore, it is observed that the benefits of steel fibres in SFRC columns diminish at high lateral drift ratios or when flexural cracks are larger. Under these conditions, the effectiveness of fibres reduces, resulting in similar failure probabilities for both PC and SFRC columns.