Abstract: Relying on the engineering background of a concrete-filled steel tubular single-pylon cable-stayed bridge under construction, aiming at the loss problem that the bearing capacity of concrete-filled steel tubular members may be reduced due to the different defect positions of core concrete, a numerical finite element model is established and analyzed by combining the bearing capacity tests of concrete-filled steel tubular members under different typical defect positions in this paper. The stress law of concrete-filled steel tube bearing capacity under different defect conditions is analyzed and discussed, and compared with the test results. The results show that the existence of core concrete defects inevitably reduce the bearing capacity of members Compared with the members with defects in the lower part, the members with defects in the upper or middle part are more likely to be destroyed. Additionally, defects located at the edge of the core concrete lead to greater loss in load-bearing capacity compared to defects in the central region, due to a weakened confinement effect, which is caused by the hoop effect of the structure.

Key words: the CFST structure, internal defects, bearing capacity, damage mechanism, finite element analysis