Numerical Analysis of Windowed Steel Tube Embedded in Concrete

Concrete-Filled Steel Tubes (CFSTs) are composite members consisting of steel tube filled with concrete. One of the main advantages of CFST is that the interaction between steel tube and concrete will increase load carrying capacity of the specimen. The local buckling of steel tube is delayed by restraint of concrete and strength of concrete is increased by confining effect provided by steel tube. Steel tubes in CFSTs are exposed to environmental deterioration. In the present study, this disadvantage is overcome by modifying CFST as steel tube embedded in concrete. The modified specimen showed better compressive strength but the bond strength was reduced. Further modification was made by providing holes in steel tube and embedding it in concrete. This improved the bond strength of specimen due to better bonding between inner and outer concrete and the compressive strength reduced due to reduction of steel section. To improve strength the specimen was modified as windowed steel tube embedded in concrete. The resulting specimen had better compressive strength and bond strength. In this paper standard size specimens are modelled and analyzed for compressive strength and bond strength by varying steel tube thickness and an optimum configuration of windowed steel section is obtained.