Abstract:In order to study the force transfer performance of concrete filled steel tubular column-h-type steel beam with lower bolted and upper welded connecting joint under middle column failure, two specimens with round and long round holes at the web connection plate were designed. The static loading test was carried out to analyze the force transmission characteristics of steel beams and the sharing of vertical load resistance by different mechanisms. Results show that the far-end steel beam of the joint is always in the elastic state during the test and its internal force can be calculated by the relevant formula, and the steel beam within the scope of the perforation plate is greatly affected by its bending resistance. In addition, the vertical resistance is mainly provided by the steel beam bending mechanism firstly and then it is replaced by the catenary mechanism after beam yielding. The bending mechanism of the steel beam exists all the time and it is always in the bending state before the failure. The long round bolt holes can improve the rotation ability of the joint, so is more favorable for steel beam axial force providing vertical force. Meanwhile, the assumption of the rigid connection of the new joint form in the frame structure is proposed and verified, and the reference value of the limit surface load is given.