Ductility and shape effect of steel tube column filled with reactive powder concrete

• This study examined the effect of reactive powder concrete on the behavior of filled steel tube columns under concentric loads • The presence of steel fibers plays an important role to increase capacity. • There are a good gain on ductility index, strength index and toughness improve when filled columns with RPC. In recent years, a modern obstetrics of concrete has been progressing, named Reactive Powder Concrete (RPC). This research presents the effect of this type of concrete on the behavior of filled steel tube columns under concentric loads. The eight columns were tested in this study, three of these columns were control specimens tested without filled concrete, with different three shape (square, rectangular, and circular) cross section with constant length (750 mm) and length to diameter ratio (10). The other five columns consist of one square column with a compressive strength of (54 MPa) that is filled with RPC without steel fibers, and the remaining four columns included two rectangular and two circulars, each one of these two columns filled with RPC without steel fiber have a compressive strength (54 MPa) and the other filled with RPC with 1.5 % steel fiber with compressive strength (92 MPa) respectively. The parameters studied in this test, ultimate stress, the effect of shape column on the load- deflection behavior, ductility index, strength index and toughness. The results obtained from this research, that an enhancement in the behavior of filled columns with increase in the ultimate strength when compare with steel columns which reached the highest percentage about 238.33 % for circular columns with compressive strength (54 MPa) and this columns had a better behavior compared with other shapes. Also, the results showed an improvement in the ductility index, strength index and toughness when filled columns with RPC, that a maximum increase of about 22.12 %, 222 %, and 680.62 % respectively.