On the performance of circular concrete-filled high strength steel columns under axial loading

Composite action of rectangular concrete‐filled steel tube columns under lateral shear force

“…The shear strength of RCFST columns can be calculated as the summation of shear strength in the steel tube and core concrete, with Equation (8).…”

“…The CFST columns are commonly applied to bear high axial loads due to the high strength capacities. The majority researches on CFST columns are also around the capacity and strength calculations under axial compression, [5][6][7][8][9] or eccentric compression conditions. 10 In recent decades, the CFST members are also applied into bridge girders or inclined columns that bear considerable bending loads.…”

Ultimate Stress of the Steel Tube in Circular CFT Stub Columns Subjected to Axial Compression

“…The composite action between the steel tube and the concrete is the key issue to understand the behavior of concrete-filled tubular members [3]. Extensive studies have been conducted to understand the behavior of the CFT columns resulting from the composite action [4] - [10]. Previous studies confirmed that the enhancement of structural properties in CFT columns is due to the composite action between the constituent elements [11].…”

“…Several observations can be made from the results of previous studies: (1) Good confinement effect is provided by the steel tube for specimen with small D/t ratio, which lead to improvements in concrete strength and ductility, and more favorable post-yield behavior of the specimen [4], [5], [9]; (2) Confinement was found more effective when the steel tube was filled with ordinary strength concrete(OSC), due to its higher deformation capacity in comparison with the high strength concrete (HSC) [12], [13]. Improvements in concrete strength and ductility were observed marginal for specimens filled with very high strength concrete [5]; (3) The use of steel tube with high yield stress in CFT columns is generally believed not necessary due to that increasing steel strength has a minimal effect on improving concrete ductility or strength [10].…”

“…Composite effect makes steel tube subjected to a complicated biaxial stress state. An elastic-perfectly-plastic theory with associated flow rule is generally adopted to model the steel tube in the analysis of CFT columns [6], [10], [14]- [16], which actually assumes the steel tube yielded and ignores the strain hardening of the steel tube [15]. However, it is known that ultimate stress of the steel tube could vary remarkably under different composite effects.…”