Influence of steel fibers on the behavior of spirally RC short columns

This study provides an experimental test to examine the behavior of spirally reinforced short columns with circular sections, strengthened by steel fibers. The volume percentage of steel fibers was (0.5, 1.0, 1.5) %. Four series comprising a total of 16 column specimens (600 mm length × 150 mm diameter) were loaded to failure under axial concentric compression load. The findings of this work are as follows: for the control specimens (columns without steel fibers), the spiral pitch influence was significant: as compared to spiral pitch of 100 mm, reducing the spacing to 75 mm, 50 mm, and 25 mm increased the ultimate load capacity by 7.6%, 11.5% and 18.4%, respectively. The steel fibers effect was very significant in increasing the ultimate load capacity of the columns. For 100 mm spiral pitch columns, these increases reached to 24.6%, 36.3% and 49.9% for the columns with 0.5%, 1.0% and 1.5% steel fibers volume percentages, respectively in comparison to the control specimen. The columns with lesser amount of spirals (less internal confinement) were strengthened by the steel fibers more than the ones with greater number of spirals. For 1.5% steel fibers volume percentage, the column with 100 mm spiral pitch was strengthened by 49.9% with steel fibers. In contrast, the one with 25 mm spiral pitch increased in strength with steel fibers by 41.4%.