Performance assessment and design of multi-storey cold-formed steel frames with strap-braced wall panels in seismic regions

<p dir="ltr">The application of cold-formed steel (CFS) wall-panel systems in high-seismic regions remains limited because of their susceptibility to premature buckling, leading to reduced ductility and energy dissipation. Moreover, current codes do not provide a unified approach for seismic design of these systems due to the limited understanding of their complex nonlinear behaviour under earthquake excitations. To address these gaps, this paper presents a comprehensive study on the seismic performance assessment and design of multi-storey CFS frames with strap-braced wall panels, considering various design scenarios. Detailed non-linear Finite element (FE) models of the CFS strap-braced wall panels were first developed in Abaqus and validated against experimental data under both monotonic and cyclic loads. Using the validated FE models, it was shown that increasing gravity load levels gradually reduced the lateral strength and ductility of the wall panels designed according to different scenarios. Subsequently, 3- and 6-storey CFS frames were designed according to Eurocode 8 with different behaviour factors (<i>q</i>=1.5, 2.5, 4) and modelled in OpenSees utilising equivalent models validated against Abaqus FE results. Non-linear dynamic analyses were then conducted under spectrum-compatible real and synthetic earthquake records corresponding to the Immediate-Occupancy (IO), Life-Safety (LS), and Collapse-Prevention (CP) performance levels. It was shown that the frames designed with <i>q</i>=2.5 generally provide the most balanced design, considering structural weight, inter-storey drift and ductility demands across all performance objectives. Through incremental dynamic analysis (IDA), it was also confirmed that using <i>q</i>=2.5 results in considerably lower global damage under a wide range of earthquake intensity levels.</p>