Static Behavior Of Square Tubed Reinforced Concrete Stub Columns With High Longitudinal Reinforcement Ratio

A steel tubed reinforced-concrete(RC) column is an ordinary RC column which isconfined by a thin steel tube and the steel tube bears no axial load at the beam andcolumn connection to maximize the effectiveness of the steel tube in confining theconcrete column. A steel tubed reinforced-concrete(RC) column is advantaged inlong-span building which has smaller section area and high bearing capacity. Thebehavior of square tubed reinforced concrete (STRC) columns was investigatedexperimentally under static eccentric compression. The main contents are asfollows:5square tube confined concrete stub columns were tested in this paper underaxial compression loading. The method of load application was attained by makingtwo10mm cuts around the specimen30mm from the top and the bottom plates ofthe specimen. The main parameters in the study is the width-thickness ratio, theexperimental results indicate that square tube confined concrete stub columns undereccentric compression was shear failure. The shear angle is between50°to65°.The constraints of the steel tube to core concrete is uneven, steel tube has yieldbefore buckled. The constraints of steel tube to core concrete in square tubeconfined concrete stub columns improves the ductility.11square tube confined concrete stub columns were tested in this paper undereccentric compression loading. The main parameters in the study included thewidth-thickness ratio、 the steel ratio and the eccentricity. The square tubeconfined concrete stub columns under axial compression was typical bendingcomponent failure modes. The concrete of compression side occurs crushingfailure, the steel tube buckling. In descending, the constraint of steel tube to coreconcrete significantly improved ductility. In the parameters of this study, the width-thickness ratio decreases slightly from133to160, the ductility slightly lower.The results of finite element simulation showed that the bearing capacity ofsquare tube confined reinforced-concrete columns can be affected by thecompressive strength of concrete、 the steel ratio and the eccentricity. Theanalysis found that as the steel ratio improving, the capacity improving; as thecompressive strength of concrete improving, the capacity improving but theductility is slightly lower.