Seismic behavior of circular TSRC columns with studs on the steel section

The tubed steel-reinforced-concrete (TSRC) column can be interpreted as a special steel-reinforced-concrete (SRC) column where the reinforcement cage is replaced with an outer encased thin-walled steel tube for confining the concrete core. In this study, seven circular TSRC columns using high-strength concrete (f_cu,150 = 97.6 MPa) were tested under combined constant axial compression and lateral cyclic load. Two primary system parameters, the axial load ratio and the arrangement of shear studs, were considered in this test. The test results indicate that the TSRC specimens exhibit excellent ductility and plastic deformation ability. The deformation of the steel section develops coherently with the high-strength concrete for both the specimens with shear studs on the steel section and those without, due mainly to the confinement from the steel tube. The lateral strength, ductility, and deformability of the circular TSRC specimens are not effectively enhanced by installing shear studs on the steel section. The axial load-moment interaction diagrams of the specimens were developed according to the ACI and EC4 methods. The predictions from the EC4 method appear to better match with the experimental results.