Joint is a vital area of concrete-filled steel tubular(CFST) structure.There is not a set of rounded theories of calculation and design method yet.The research work of CFST lags behind the need of practical application.As a part of fundamental research about joints of CFST columns and beams

the joint’s mechanical properties under axial compression on the base of experiment of steel about the worst joint form(steel beam is directly welded on steel tube) are introduced and can be adopted in design of similar CFST joint.The failure type and bearing capacity under axial compression are discussed here.The result shows that the bearing capacity under axial compression is identical to the result calculated by using formula recommended in rules.The conclusion can be used in the design of CFST joint.