Study on seismic behavior of assembled lightweight concrete-filled cold-formed thin-walled steel composite shear walls

To enhance the seismic performance of cold-formed thin-walled steel (CTS) composite wall filled with foam concrete, a novel type of lightweight concrete-filled CTS shear wall is proposed in this paper. The wall comprises rectangular CTS end studs filled with self-compacting lightweight concrete (SLC), high-strength foam concrete-filled CTS inner walls, and double-layer wall panels. Four full-scale specimens of lightweight concrete-filled CTS shear wall were subjected to reversed cyclic load. The influences of reinforced end stud, double interior stud and stud web openings on the seismic behavior such as failure mode, bearing capacity, lateral stiffness, deformation, ductility, stiffness and bearing capacity degradation, energy dissipation capacity, were investigated. The experimental results reveal that the specimens exhibit the shear failure characteristics, with oblique cracks observed in the wallboards and foam concrete. The lateral deformation during the elasto-plastic stage shows shear deformation, with the displacement angle ranging from 1/62 to 1/45 at peak load. Moreover, the adaptation of rectangular end stud and interior stud filled with SLC effectively prevents the local buckling failure, and significantly improves the shear bearing capacity and lateral stiffness of the walls. Additionally, increasing the number of openings in the stud webs prevents bond slip between studs and concrete core, leading to a noticeable enhancement in shear strength, lateral stiffness and energy dissipation capacity of the walls. It also delays the degradation of strength and stiffness. Based on the bearing capacity superposition principle, a shear bearing capacity calculation formula for this type shear wall was proposed, and the calculation results demonstrated good agreement with the test results.