Equivalent Viscous Damping Characterisation for Direct Displacement-Based Design of CFS Strap-Braced Shear Wall Structures

A direct displacement-based design method has been developed for cold-formed steel strap-braced shear walls. An equivalent viscous damping–ductility relationship, established from 16 cyclic tests using Jacobsen’s area-based approach and refined through nonlinear time-history analyses, stabilises near 10% for ductility exceeding 4. Story yield displacement was formulated by combining the deformation contributions of all shear-wall components. Designs for 3- and 5-story case-study buildings, validated using 20 spectrum-compatible accelerograms, maintained mean story drifts below the 2.5% target. Compared with force-based design, the original direct displacement-based design resulted in 4.02% (3-story) and 25.40% (5-story) lower base shear.