Seismic performance of high-strength lightweight foamed concrete-filled cold-formed steel shear walls

To improve the seismic behavior of cold-formed steel (CFS) shear walls, cold-formed steel high-strength lightweight foamed concrete (CSHLFC) shear walls with straw boards are proposed. This study conducted tests of six full-scale shear wall specimens to investigate the failure mode, load-bearing capacity, ductility, stiffness characteristic and energy dissipation capacity. The test parameters included HLFC density grade, stud section area, wall thickness and vertical load. Test results indicated that HLFC has greater effect on seismic performance and failure mode of the shear walls. The failure modes were cracking and crushing of HLFC, cracking of straw boards, local buckling of studs, and relative slippage between HLFC and studs, which made the wall exhibit good ductility and energy dissipation capacity. Compressive bearing capacity of HLFC and restrictive effect of HLFC on steel frame increased the shear strength and stiffness. The most effective way of improving seismic performance was to increase wall thickness, followed by increasing HLFC density grade and stud section area, but increasing vertical load had an adverse effect on seismic performance. Based on experimental results and mechanism analysis of shear walls, a simplified design formula for predicting the shear strength was proposed base on strut-and-tie model. The calculated results obtained by the proposed formula showed better agreement with the experiment results compared with the results from ACI 318-14, EC8 and CNS 383-16 standards.