Numerical analysis and design approach for mid-rise cold-formed steel load-bearing wall buildings to resist progressive collapse

Progressive collapse occurs due to the propagation of localized initial failures caused by extreme or abnormal events. Current design methods attempt to prevent such collapses by enhancing connectivity between building components and improving the strength of individual members. These measures ensure that the loads previously carried by failed components are effectively redistributed to the remaining structural system. However, existing design methods have primarily been developed based on studies of framed buildings, with limited attention on mid-rise cold-formed steel (CFS) load-bearing wall buildings. This highlights the need for a specific design approach for the building to resist progressive collapse, as pursued in this paper. To analyse the structural performance after stud wall removal, numerical simulations of entire buildings were employed. An 8-storey archetype building was first designed, considering vertical gravity and wind (leeward) loads, which incorporated the recently proposed joist-to-joist bottom plate (JJ) connection from the literature to enhance the structural robustness. Numerical analysis of the archetype building was then performed under five stud wall removal cases. To reduce computational cost, a simplified finite element (FE) model was proposed. Based on observations from the simulation results, a hand calculation design approach was developed. This approach includes methods to account for dynamic effects and tributary areas, as well as a design strategy to reduce the required design strengths of structural members. Comparisons are made between the proposed hand calculation approach and the predictions obtained from numerical analysis. • Design of an archetype mid-rise cold-formed steel building. • Simplified finite element model for mid-rise cold-formed steel buildings. • Numerical analysis of cold-formed steel buildings under stud removal scenarios. • Design approach for cold-formed steel buildings to resist progressive collapse.