Analytical behaviour of concrete-encased CFST column to steel beam joints

The concrete-encased concrete-filled steel tubular structures have been used in some high-rise buildings in China. This kind of steel and concrete composite structure has higher strength and better fire performance when compared to its concrete-filled steel tube counterpart. However, very few research has been conducted for the behaviour of concrete-encased concrete-filled steel tube to steel beam joints, which hinders the application of this kind of structures. This paper reports the analytical behaviour of concrete-encased concrete-filled steel tube to steel beam joints. Various connection details are proposed, and the corresponding numerical models are established and verified. The behaviour of different kinds of joints is compared using the verified numerical models. It is shown that for the joint which has the internal diaphragm, the strength and stiffness characteristics are the best among all joint specimens.