BEHAVIOUR OF DUAL STEEL FRAMES WITH INNOVATIVE DOUBLE SKIN COLD-FORMED STEEL CONCRETE COMPOSITE SHEAR WALLS

Dual systems that combine moment-resisting frames with innovative replaceable bracing systems offer significant advantages over conventional solutions. The key benefits of these systems include energy dissipation at specific locations and a re-centring capability, which substantially reduces repair costs. However, the design of such systems must meet specific requirements, such as using higher steel grades to ensure the part of the system remains elastic and structural solutions for the double skin cold formed shear wall filled with concrete which ensure the system’s ductile behaviour. This paper presents an assessment of dual systems, based on finite element analysis, that integrate moment-resisting multi-story frames with innovative double-skin cold-formed steel concrete composite shear walls. The steel frame consists of three bays with a central braced frame and two adjacent moment-resisting frames. The shear wall, acting as a bracing system, consists of corrugated cold-formed steel sheets filled with concrete which are connected with intermediate shear connectors forming a sandwich steel-concrete-steel panel. In the first step, nonlinear analyses of individual shear wall panels are conducted taking into account influences of steel sheet thickness, concrete strength and type of shear connection. Using the resulting load-displacement behaviour of the analysed shear walls, pushover analyses are performed. The performance of the analyzed systems is discussed in terms of collapse mechanisms, capacity curves, overstrength ratios, behaviour factors, and potential improvements for the shear wall's performance. The analysed systems demonstrated their dual behaviour and re-centring capabilities, but further research on different shear wall typologies will provide deeper insights into their practical applications.