Seismic behavior of circular tubed steel-reinforced concrete column to steel beam connections

The tubed steel-reinforced concrete (TSRC) column is a special type of SRC columns where the longitudinal reinforcement and reinforcement cage in the SRC column are replaced by a thin-walled steel tube. Without any traditional reinforcement, concrete pouring becomes easier in a TSRC member. Although the TSRC columns possess high load-carrying capacity and good ductility performance in seismic zones, the seismic behavior of TSRC column to beam connections has not received much attention, which limits the application of TSRC columns. This paper aims to investigate the seismic behavior of circular TSRC column to steel beam connections with cross diaphragms. Four such connection specimens were tested under cyclic loading, considering the thickness of joint tube, the height of extended tube, and the axial compression ratio of columns. Based on experimental results, the failure progression, load-displacement curves, and stresses for the circular TSRC column to steel beam connections are discussed. The favorable seismic performance for such connections is demonstrated and a design model for determining the joint strength is proposed in this paper.