Experimental Behavior of SFRC Columns under Seismic Loads

The present paper aims at investigating the influence of steel fiber reinforcement on the behavior of concrete columns under seismic loading. In particular, the use of Steel Fiber Reinforced Concrete (SFRC) in columns was experimentally evaluated with the purpose of increasing the stirrups spacing without compromising the drift capacity and the dissipation energy of the column. Sixteen full-scale axially loaded cantilever columns were tested under reversed cyclic horizontal loading. Results from eight Reinforced Concrete (RC) columns with and without fiber reinforcement are reported. In particular, hooked steel fibers with a volume fraction of 1.0% were adopted for SFRC. The spacing and the diameter of the stirrups were varied in order to verify their influence. Both mono-axial and bi-axial quasi-static tests were performed by keeping constant the vertical load. Experimental results show that fiber addition in RC columns prevents a premature spalling of concrete cover under seismic actions and increases the initial stiffness as well as the energy dissipation of the columns, especially for mono-axial loads which resulted to be a less severe load condition with respect to the bi-axial one. Nevertheless, it seems that, despite the fibers addition, the increased stirrup spacing reduces the columns ductility.