Experimental Study and Mechanism Analysis of Concrete-Filled Square Steel Tubular Columns Reinforced by Rhombic Stirrups Under Axial Compression

The square steel tube component has a beautiful appearance, simple joint connection, and it is widely available. However, the uneven distribution of effective constraints in cross-section hinders its application. A novel concrete-filled tubular column was tested under axial compression. There were 11 specimens [10 columns reinforced with rhombic stirrups 90-degree internal angle (SSSC specimens) 1 (SC specimen)]. load-displacement curves, law failure process, mode, mechanism analysis, energy consumption, ductility, stiffness degradation described, we then investigated influence stirrup diameter, side length, spacing, thickness, aspect ratio, ratio on mechanical properties specimens. results show that process SSSC basically same. ultimate mode an 4 local buckling failure. 5 6 failed due to bending plastic stage. bulged out different degrees most debonding areas. longitudinal bars also produced outward deformation larger bulging area tube. Some broken later stage loading. characteristics curve changed changing spacing. strength constraint had obvious bearing capacity. In certain range ( ? s = 8.97% ? 9.05%), weakening lateral restraint cage greater adverse effect capacity than corner. 9.49%), strengthening corner improved specimen, however, ductility performance reduced. opposite true for cage.