Nonlinear Modeling of Concrete‐Filled Composite Coupling Beams in Coupled SpeedCore Systems

ABSTRACT This study shows the development and comparative evaluation of advanced nonlinear inelastic three‐dimensional finite element modeling (FEM), two‐dimensional FEM, and simple fiber‐section‐based FEM for concrete‐filled composite coupling beams (CBs) and CB‐to‐wall connections in the coupled SpeedCore system. The three‐dimensional FEM is verified against available experimental results and observations. Results from experiments and detailed three‐dimensional FEM are benchmarked for developing and proposing effective stress–strain relations of concrete (compressive behavior) and steel plates used in composite CBs. The proposed phenomenological stress–strain relations account important factors governing structural responses: ( i ) steel yielding, ( ii ) steel strain hardening, ( iii ) steel local buckling, ( iv ) nonlinear behavior of concrete, ( v ) concrete cracking and confinement, ( vi ) biaxial stress state, etc. The effective stress–strain relations are valid for flexure‐critical composite CBs and should not be directly extended to shear‐critical members. The effective stress–strain relations are implemented to develop nonlinear inelastic two‐dimensional FEM and simple fiber‐section‐based FEM of concrete‐filled composite CBs (flexure critical CBs) and CB‐to‐wall connections. The detailed nonlinear inelastic three‐dimensional FEM is suitable for advancing research and conducting numerical investigations at the component level. The nonlinear inelastic two‐dimensional FEM or simple fiber‐section‐based FEM is recommended for analyzing and designing multistory buildings. The simple two‐dimensional and fiber‐section‐based FEM are suitable for conducting performance‐based design of the coupled SpeedCore system.