Behaviors of axially loaded square concrete-filled steel tube (CFST) Stub columns with notch in steel tube

Compressive tests of the CFST stub columns with artificial notches in the steel tubes were conducted in this paper to investigate the effects of the material imperfections of steel tubes on column performances. The load-strain responses, column strength and confining effects were discussed in detail. A parametric study, including the notch length, notch orientation, notch location and ductility, was also conducted. The results indicate that the notched CFST specimens have quite different failure modes from the intact CFST specimens. A notched CFST specimen may fail by bulging or closing of the notch, which was determined by the notch orientation. The results also show that the notched CFST specimens had lower mechanical performances than the intact CFST specimens because the notch steel tube could not offer sufficient confining effect on the concrete core inside it. Based on the experimental results, a practical calculation formula for the bearing capacity of notched CFST columns was proposed, which gave well agreement with the experimental results.