Abstract
This article presents the experimental and finite element (FE) analyses of two conventional rectangular concrete-filled steel tubular (CFT) stub columns, two stiffened rectangular concrete-filled steel tubular (SCFT) stub columns, and two stirrup confinement rectangular concrete-filled steel tubular (CCFT) stub columns concentrically loaded in compression to failure. The influences of the ductility and ultimate bearing strength of these stub columns with stiffening ribs or spiral stirrup confinement were discussed. Abaqus was used to establish a 3D FE model and analyze the properties of CFT stub columns subjected to axial compression. The effect of the concrete core and rectangular steel tube under loop stirrup confinement was discussed. Analytical results showed that spiral stirrup confinement can availably retard the local bucking of the rectangular steel pipe, and the effect of the spiral stirrup confinement was stronger than that of stiffeners. The DI values of SCFT and CCFT were 21.9% and 31.9% larger than those of CFT, respectively. The ultimate capacity values of SCFT and CCFT were 10.2% and 18% larger than those of CFT, respectively. The ductility and ultimate bearing strength of the specimens improved effectively under spiral stirrup confinement, and the ductility of the CCFT columns was preferable to that of the SCFT columns.
Highlights
concrete-filled steel tubular (CFT) stub column (CCFT), to overcome the shortage of conventional CFT stub columns and steel-reinforced concrete columns
(1) CCFT stub columns have a lower steel content than steel-reinforced concrete columns, thereby overcoming various problems, such as complicated application technology, difficult concrete vibration and pounding, and large amounts of formwork caused by multiple construction procedures and complicated joint construction
(2) Unlike in the conventional rectangular CFT stub columns, the rectangular steel tube mainly acts as a restriction on the concrete in the corner, and the inward-cut elliptic stirrups or spiral stirrups act as a restriction on the core concrete, and the local buckling of the side wall of the steel tube was restrained. erefore, the ductility and bearing strength of the rectangular CFT stub columns are considerably improved while retaining the convenience of joint construction
Summary
CFT stub column (CCFT), to overcome the shortage of conventional CFT stub columns and steel-reinforced concrete columns. On the basis of the conventional rectangular CFT columns, the stirrup is used to strengthen the restraint of concrete. In comparison with steel-reinforced concrete columns, such as square, circular, and rectangular CFT stub columns, CCFT features the following advantages. (1) CCFT stub columns have a lower steel content than steel-reinforced concrete columns, thereby overcoming various problems, such as complicated application technology, difficult concrete vibration and pounding, and large amounts of formwork caused by multiple construction procedures and complicated joint construction. Is study analyzed two conventional rectangular CFT, two ribbed rectangular CFT, and two stirrup confinement rectangular CFT axial compression stub columns. E mechanical properties of the axial compression specimens were explored under different constraint conditions. A 3D finite element (FE) model was developed for numerical analysis by using Abaqus, and the composite action among the concrete, stirrups, and steel pipe was revealed
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