Parameter analysis and design on socket CFST column-cap beam joint with UHPC grouted connection

The excellent mechanical properties of concrete-filled steel tube (CFST) make it a competitive alternative to column-cap/foundation cap socket connections in accelerated bridge construction (ABC). To investigate more research parameters and facilitate the seismic design of socket CFST column joints, a detailed numerical analysis model of socket column-cap beam joint was established and verified by experimental data, and the bearing capacity and failure modes of socket joints under the dimensions of the CFST parts and their material properties were investigated as well. It is found that the size of steel tube, the strength of steel tube, the socket depth of CFST, and the type of forming hole have significant effects on the strength and failure modes of column to cap beam socket joints. This study also proposed a moment calculation method for socket joints that can accurately predicts the bearing capacity under different failure modes. Finally, a design process was developed to facilitate the widespread application of this socket CFST column-cap beam joint with Ultra High-Performance Concrete (UHPC) grouted connection.