Inelastic Force-Deformation Response of Joint Shear Panels in Beam-Column Moment Connections to Concrete-Filled Tubes

In the design of beam-to-column subassemblies in concrete-filled steel tubular column systems, a design formula established by the Architectural Institute of Japan (AIJ) is applied. However, in the current AIJ standard, the scope of the design formula is limited to ordinary material strengths; i.e. up to an unconfined compression strength of 36 MPa for concrete and tensile strength of 490 MPa for structural steel tubes. So, the effect of higher material strengths on subassembly behavior is studied in this investigation. The experimental results presented in this paper verified that the above-mentioned AIJ design formula is applicable up to an unconfined compression strength of 110 MPa for concrete and tensile strength of 809 MPa for structural steel tubes. An analytical model for the restoring force characteristics of the shear panel in the subassemblies was also proposed, and was found to reproduce the experimental results with good accuracy.