Ultimate bearing capacity of multi-cavity steel plate-concrete composite shear walls considering flexure-shear

Steel plate-concrete composite shear walls are widely utilized in high-rise buildings to enhance seismic performance, owing to their superior load-bearing capacity and ductility. However, existing methods for calculating the ultimate bearing capacity of multi-cavity double steel plate-concrete composite shear walls remain limited, as the influence of single-cavity width is generally neglected and the actual flexure-shear interaction mechanism is not adequately represented. As the primary lateral force-resisting elements, shear walls must be designed to ensure that shear failure is precluded until after flexural yielding occurs. Based on a compilation of 114 experimental datasets of multi-cavity double steel plate-concrete composite shear walls, this study systematically analyses the failure modes and capacity control mechanisms under combined flexure-shear interaction. A Grey relational analysis(GRA) was conducted, identifying the single-cavity width as a critical parameter influencing lateral bearing capacity. Consequently, calculation models for ultimate lateral bearing capacity were established corresponding to three distinct failure modes: flexure-controlled, shear-controlled, and mid-height shear-controlled failure. Validation results demonstrate that the ratio of calculated to experimental values has a mean of 1.003 and a coefficient of variation (COV) of 0.06, indicating significantly higher accuracy than existing code-based methods. Compared with existing code-based formulae and previous studies, the main advances of this study lie in the quantitative identification of key parameters through GRA, the establishment of a failure-mode classification logic for three governing modes based on flexure-shear interaction, and the development of a unified calculation model for the ultimate lateral bearing capacity. These findings provide a valuable reference for the design of multi-cavity steel plate-concrete composite shear walls and offer an evidentiary basis for the improvement of current design codes.