To explore the improvement mechanism of welding round steel at soffit on the flexural performance of eccentric concrete-filled steel tube (CFST) members

we established a numerical model of CFST beams reinforced with round steel by using ABAQUS software and verified the model by test results. By analyzing the bending momentdeflection curve

bending momentaxial strain curve

hoop strain curve

restraint index

and neutral axis offset of eccentric CFST members reinforced with round steel

the improvement mechanism of the flexural performance of the eccentric CFST members was revealed. Besides

the influence of the diameter of the round steel and the slenderness ratio of the beams on the flexural performance of eccentric CFST members reinforced with round steel was analyzed. Results show that welding round steel could lower the position of the neutral axis of the section and increase the hoop strain of the steel tube on the compression side. Therefore

the concrete area in compression was increased

and the restraint effect of the steel tube on the compression side on the concrete was enhanced. Furthermore

the flexural bearing capacity and flexural stiffness of the eccentric CFST members were improved

and the larger the diameter of the round steel

the greater the improvement. The ultimate bending moment of the eccentric CFST members decreased with the increase in the axial compression ratio

and the larger the diameter of round steel and the slenderness ratio of beams

the greater the reduction. Welding round steel had a better effect on improving the bending performance of the eccentric member with a large slenderness ratio

and the larger the axial compression ratio

the better the improvement effect.