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

•A three-dimensional numerical model that can accurately predict the nonlinear behavior of the novel socket joints was developed.•The influence of performance parameters on the mechanical properties of the socket joint were studied.•The modified moment capacity calculation method of the socket joints under different failure modes was verified.•The convenient design process of the socket CFST column-cap beam joint with UHPC grouted connection was proposed.