Research on Behaviors of Steel Fiber Reinforced Concrete Filled Steel Tube Columns under Axial Load

Many in-fill materials are used to improve ductility of concrete filled steel tube (CFST), due to meeting need for a change of seismic design perspective form the previous emphasis on structural strength to emphasis on structural ductility and energy absorption. Among the various in-fill materials, steel fiber is gaining attention in the CFST column. This paper investigates effect of volume fractions of steel fiber to concrete on the behavior of short steel fiber reinforced concrete filled steel tube columns under axial compression. The volume fractions of steel fiber to concrete are 0.6, 0.9 and 1.2%. The results indicate that steel fiber reinforced concrete filled steel tube columns appears to have a significant increasing trend in ductility, and have a slight increasing trend in load capacity with volume fraction of steel fiber to concrete increasing. The failure mode of the composite columns is similar with that of CFST.