The Study On The Stiffness Of Joint Of Steel Beam To CFT Column In Frame Structure And The Effect On The Behavior Of Frame Structure

With wide use of CFT (concrete-filled tube) structure, more and more attentions have been paid to the design of CFT joints. There have been a great number of researches on CFT joints. But most of them focused on the ultimate resistance of certain joints. And the study on the stiffness of CFT joints has been seen seldom. As a matter of fact, the influence of joint's stiffness on the whole structure can hardly been neglected. As a part of "The Study on the Restraining Stiffness of Joints of CFT frames", a project supported by National Natural Science Foundation of China, this paper have done further research on the stiffness of CFT joint in frame structure and its effect on the behavior of frame structure on the basis of the result of researches on the earlier stage of the project. The finite-element model of the CFT frame was analyzed in ANSYS. Two CFT frames were tested and the result was compared with the finite-element analysis for the verification for the model. The flexibility of connections and the rigid zone were considered in the member-bar model of the CFT frame. The comparison between the model of this paper and the traditional model showed the result of the former approached the test result more than the one of the latter. The geometric parameters of the finite-element model of joint were changed in a series of analysis of the isolated CFT joint in ANSYS in order to find out how the factors affect the performance of the connection. A general M — 0 formula of the connection was sum up to offer designers a reference for designing CFT joints and analyzing frames. The affecting factors of joint were changed in the analysis of the frame to find out how the flexibility of connections and the level of flexibility affect the behavior of the frame.