Seismic performance of CFS–foamed concrete composite walls: Experimental investigation of the effects of flanges and dry connections

Although cold-formed steel (CFS) shear walls with infill materials have been widely investigated, experimental evidence on flanged, dry-assembled CFS–foam concrete composite shear walls (CFS-FCCWs) under cyclic loading remains critically limited—particularly with respect to the synergistic effects of cross-sectional geometry and connection detailing on failure mechanisms, ductility, and energy dissipation. To address this gap, this study presents a comprehensive experimental program involving six full-scale CFS-FCCW specimens subjected to quasi-static cyclic loading. The test matrix systematically varied two key parameters: (i) cross-sectional configuration (rectangular, T-shaped, and H-shaped) and (ii) dry connection type (web, end, and angle), all designed in compliance with GB/T 50011-2010. Results reveal that damage in flanged specimens primarily concentrated in the web region, characterized by a flexural-shear failure mechanism. The H-shaped configuration (CFS-FCCW-3) exhibited superior performance: peak load increased by 74.8% to 316.3 kN, and ductility coefficient improved by 30.5% to μ = 2.56 compared to the rectangular wall. In contrast, the T-shaped wall showed vulnerability at the free web end, with significantly enhanced performance under tensile flange loading—positive direction yielding 33.1% higher peak load and 23.0% greater ductility than the negative direction. All dry connections performed reliably without premature failure, confirming compliance with code provisions. Among them, the web connection underutilized adjacent materials; the end connection ensured structural integrity; and the angle connection demonstrated optimal energy dissipation capacity. Considering overall seismic resilience, constructability, and transport efficiency, the angle connection is recommended for practical implementation in prefabricated systems. Design recommendations are proposed to enhance the seismic behavior of flanged CFS-FCCWs, supporting the development of high-performance, modular structural solutions for seismic regions.