Structural Behavior of Self-Compacting Concrete-Filled Small Square Steel Tube Columns under Concentric, Eccentric, And Flexural Loads

This study introduces an innovative approach to replace traditional steel bars with small cross-section steel tubes in self-compacting concrete columns. The structural behavior of square steel tube-reinforced self-compacting concrete (SSTR-SCC) columns was investigated experimentally. Sixteen specimens were cast and tested under concentric, eccentric, and flexural loads. Four specimens reinforced with 12 mm diameter deformed steel bars were considered as reference specimens, and the remaining 12 specimens were reinforced with small square steel tubes. All the specimens were laterally confined with 10 mm square shaped steel ties at 50 mm spacing. Three different cross-sectional dimensions of square steel tubes (25 mm x 25 mm, 30 mm x 30 mm, and 35 mm x 35 mm) with a constant thickness of 2 mm were used as longitudinal reinforcement in the SSTR-SCC specimens. The specimens were divided into four groups, with four specimens in each group. From each group, one specimen was tested under concentric load, one under 25 mm eccentric load, one under 50 mm eccentric load and one under flexural load. The experimental results demonstrated that SSTR-SCC specimens exhibited superior load-carrying capacity and ductility compared to the reference specimens. The SSTR-SCC specimens were found to be a scientifically significant and structurally efficient alternative to conventional reinforced concrete columns, offering an effective solution for enhancing durability and load resistance in modern construction.