Experimental Study on the Bond Strength of Concrete-Steel Composite Columns

Abstract: In this study the bond strength of concrete filled steel tubes (CFST), has been experimentally investigated. 38 short, CFST members filled with 6 types of concrete mixes were tested. Push-out test is carried out to examine the bond carrying capacity. The steel tubes were welded type with the nominal inside diameters of 3, 4, 6 and 8 inches and a square hollow section with outside dimensions of 135 mm square. Plasticizer and expansive admixtures were used in some concrete mixes. According to test results expansive additive has a considerable effect on the steel-to-concrete bond strength. Effect of the expansive additive on the bond strength of CFST members increases with increase in steel tube diameter.