Investigation of Bond-Slip Behavior in Concrete-Filled Steel Tubes

This study investigates the bond-slip behavior at the steel-concrete interface of square concrete-filled steel tubes (CFSTs) through a series of six push-out tests conducted under controlled laboratory conditions. Six specimens were prepared using steel profiles with different external dimensions and thicknesses, covering a range of d/t ra-tios to understand how this factor influences the push-out capacity. The investigation focuses on areas with ge-ometric discontinuities, such as CFST column-to-frame connections, where effective stress transfer between the concrete core and the steel tube is crucial for composite action. The experimental findings, including the defor-mation patterns of the steel tube and load-slip curves, offer insights into the bond-slip behavior of smooth CFSTs.