Seismic behavior of cold-formed steel high-strength foamed concrete shear walls with straw boards

To satisfy the requirements of thermal insulation property and load-bearing capacity of cold-formed steel (CFS) shear walls in mid-high buildings, a new type of CFS shear wall referred to as cold-formed steel high-strength foamed concrete (CSHFC) shear wall with straw boards on both sides is proposed in this study. Straw board is an one-way slab consisting of horizontally distributed natural straw fibers and has excellent thermal property. High-strength foamed concrete (HFC) is a new type of lightweight foamed concrete with high compressive strength. Seven full-scale specimens with different configurations were conducted under reversed cyclic loading to assess the failure mode, load-bearing capacity, ductility, lateral stiffness and energy dissipation. The test parameters include HFC strength grade, aspect ratio, stud section type and opening of the specimens. Compressive bearing capacity of the HFC and restrictive effect of the HFC on the studs and screw connections significantly improved the wall's shear strength and lateral stiffness. Together with bond-slip behavior between the HFC and the studs, HFC cracking and straw boards cracking, these makes the walls exhibit better ductility and energy absorption. The failure mode typically includes local buckling of the studs, inclined cracking of the HFC and straw boards and relative slippage between the stud webs and the HFC. Enhancing HFC strength grade and increasing studs' section area could effectively improve the seismic behavior, whereas increasing walls' length could improve shear capacity and lateral stiffness. Comparison of the results between CSHFC shear walls and traditional CFS shear walls shown that the seismic performance of the CSHFC shear walls was much higher than those of traditional CFS shear walls.