Experimental and numerical study on the seismic performance of irregularly concrete-filled steel tube column to steel beam joints with inner semi-diaphragm

This paper studies a new kind of irregular-shaped concrete-filled steel tube column to H-shaped steel beam joints with inner semi-diaphragm (ICFSTC-Joint), which exhibits excellent seismic performance, bearing capacity and stiffness in the engineering structures. Firstly, the experiments of four ICFSTC-Joint specimens under cyclic loading are carried out to investigate their hysteretic behavior and failure mode. It is found that the axial compressive ratio has significant negative influence on the hysteretic behavior of ICFSTC-Joint. Secondly, the finite element (FE) models of ICFSTC-Joint are established and verified by the experimental results. The hysteretic curves and skeleton curves of FE model are obtained and agree well with the experimental results. Thirdly, a parameter analysis on the size of diaphragm is carried out by using established FE model. This paper can provide guidance for the engineering design of CFST column to beam joints under earthquake.