Reversed cyclic performance of cold-formed steel shear walls with reinforced end studs

TO improve the shear performance of cold-formed steel (CFS) shear walls and to prevent a structure from collapsing due to compression buckling of the end studs, shear walls with concrete-filled rectangular steel tube columns as end studs were proposed. Cyclic loading tests on nine full-scale CFS shear walls with reinforced end studs were conducted concerning the influence of stud type, sheathing material and openings. The results showed that: (1) the walls' shear strength will be improved because the screws will be less able to tilt due to the concrete core in the reinforced end studs; (2) the walls' ductility may be improved by increasing stud thickness, but no meaningful difference in shear strength was observed when the interior stud section's type was replaced with a coupled C section; (3) compared to a wall that was individually sheathed with autoclaved lightweight concrete slabs on the external side, the shear strength could be increased by approximately 58.1% due to the addition of supplementary bolivian magnesium boards, which would be installed under the condition of an identical sheathing setup on the inner side; (4) the wall's shear capacity would be decreased due to an increase in the opening's size, and this shear capacity would also be impacted by the opening's position. Based on the experimental results and a bearing mechanism analysis of CFS shear walls with reinforced end studs, a simplified method for predicting the perforated walls' shear capacity was proposed, and the differences between the calculated and experimental results were within 8%. (C) 2015 Elsevier Ltd. All rights reserved.