Nonlinear modeling methods for cyclic analysis of double-skin composite shear walls

The double-skin composite walls (DSCWs) are attractive as the main seismic element in structures. The interaction between concrete and steel provides DSCWs with superior seismic and structural performance. An urgent need is to develop accurate and reliable numerical modeling methods to analyze the mechanical mechanisms of DSCWs and predict their responses in structures. This paper provided both continuum finite element (CFE) modeling and fiber-based modeling methods for the nonlinear cyclic analyses of DSCWs. The common problems of numerical simulations in existing studies were summarized and discussed. An alternative CFE modeling method using the ABAQUS program was proposed through explicitly modeled concrete discrete cracks and CVGM (cyclic void growth model)-based steel fracture criterion. The passive confinement of concrete and the geometric local buckling of steel faceplate were taken into account. As for the system-level analyses, a fiber-based modeling method was developed. The concrete confining effect, as well as the local buckling and ductile fracture of steel fibers, were considered and driven by the physically reliable uniaxial constitutive models. Both the CFE models and fiber-based models were validated by experimental results, and a good agreement was achieved. Two modification methods for the enhancement of confining effect due to the interactional constraints of concrete in continuous multi-cavities were proposed. Furthermore, the internal force responses of steel sheets were extracted by CFE simulation results and compared with the steel fibers of the fiber-based model, to verify the reliability of the RSMM (reinforcing steel material model) parameters that control the buckling and fracture of the steel fibers.