Mechanical Behavior of Circular Steel–Concrete Composite Stub Columns

In an experimental and analytical study on the mechanical behavior of circular steel–concrete composite stub columns, 13 specimens were tested. To examine different mechanical behaviors of the columns, three loading conditions were studied. Three-dimensional nonlinear finite-element models were established and verified with the experimental results. The analytical models were also used to study how the behavior of the column was influenced by the bond strength between the steel tube and the concrete core and by the confinement of the concrete core offered by the steel tube. The results obtained from the tests and the finite-element analyses showed that the mechanical behavior of the column was greatly influenced by the method used to apply the load to the column section. The bond strength had no influence on the behavior when the steel and concrete section were loaded simultaneously. On the contrary, for the columns with the load applied only to the concrete section, the bond strength highly affected the confinement effects and, consequently, the mechanical behavior of the columns.