A Specific Procedure for Seismic Design of Cold-Formed Steel Housing

Abstract

ABSTRACT:In the last years, the seismic performance of cold formed steel (CFS) systems has been object of study by a large number of research teams. The main parameters influencing the system behaviour under horizontal loads have been defined and the possible mechanisms of collapse have been identified. Therefore, at the moment, the development of upgraded specifications and design tools that could be readily used by designer is a must. For these reasons, this paper aims to propose a seismic design procedure that allows the shear wall components to be defined in few steps. The procedure is based on the recognized assumption that the best performance of a CFS shear wall is achieved when the sheathing-to-stud fasteners failure is reached. Moreover, it accounts the results of previous studies that defined the relation between behaviour of shear wall and fastener spacing. Hence, by defining three nomographs, the proposed procedure allows the sheathing-to-stud fasteners and all the other shear wall components to be defined. The latter are determined in accordance with capacity design criteria. Finally, the applicability of the presented procedure is verified through a case study.Keywords: Design nomographs, cold-formed steel, housing, linear dynamic analysis, nonlinear static analysis, seismic design, sheathing panels INTRODUCTIONThe growing demand of high performance housing is increasing the interest for cold-formed steel (CFS) structures. These structures are realized with a repetitive number of light gauge cold-rolled steel profiles, produced off-site in controlled environment and, then, assembled on-site with mechanical connections. These characteristics provide them lightness, rapid on-site erection, dimensional stability, high structural performance and considerable potential for recycling and reuse of all the materials. In particular, the spreading use of these constructions in countries as Japan shows the wide applicability of these systems also in seismic zones (Figure1). The global horizontal response of CFS structures under seismic actions basically depends on the shear response of CFS walls that are usually sheathed with metal sheets or panels (sandwich panels, wood-based or gypsum-based panels). Moreover, when the sheathing has adequate strength and stiffness and it is effectively connected with the frame, then the interaction between profiles, sheathing panels and sheathing-to-frame connections can be advantageously taken into account in the structural analysis. In this case, the definition of shear wall elements (studs, sheathing panels, sheathing-to-frame connections, and frame-to-foundation anchors), that constitute the main lateral resisting system in case of seismic actions, is a key point for the design. Currently, a relatively large database of experimental investigations carried out on different CFS wall assemblies subjected to in plane shear loading has been obtained by Gad et al. [7]. As result, the main parameters influencing the shear behaviour of walls have been identified. As a consequen...

Behaviour Factor Evaluation of Sheathed Cold-Formed Steel Structures

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Numerical Modelling of CFS Three-Story Strap-Braced Building under Shaking-Table Excitations

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