Summary An experimental program was performed for evaluating the seismic response and fragilities of nonstructural lightweight steel drywall partitions, also considering the interaction with structural elements and other nonstructural building components, ie, outdoor façade walls. Therefore, in‐plane quasi‐static reversed cyclic tests were carried out on 8 specimens of indoor partition walls infilled in a frame and on 4 specimens of indoor partition walls connected at its ends with transversal outdoor façade walls. Constructive parameters under investigation include type of connections used for connecting the indoor partition walls to the surrounding elements, stud spacing, type of sheathing panels, and type of jointing finishing. The effect of the constructive parameters on the lateral response in secant stiffness and strength is examined. Furthermore, the main damage phenomena observed during the tests are reported and associated to 3 damage limit states distinguished for the required repair level for the tested partition walls. Fragility curves are used for the experimental assessment of seismic fragility of the tested specimens, in accordance with the interstorey drift limits required by the European code. Finally, the quantitative estimation of the repair action costs starting from the damage observation is also developed. The obtained results could be considered a starting point for developing the in‐plane seismic design assisted by testing of lightweight steel drywall partition walls.

Strap-braced stud walls.2 HIGHLIGHTS  The seismic behaviour of CFS strap-braced walls is evaluated by experimental investigation. The global inelastic response of a wide range of X-braced walls is discussed. The local behaviour is investigated by tests on material and connection systems. The behaviour factor provided by AISI S213 are confirmed by the experimental tests. The capacity design rules of Eurocodes are also reliable for the CFS structures. ABSTRACTThe development of light weight steel structures in seismic area as Italy requires the upgrading of National Codes. To this end, in the last years a theoretical and experimental study was undertaken at the University of Naples within the Italian research project RELUIS-DPC 2010-2013. The study focused on "all-steel design" solutions and investigated the seismic behaviour of strap-braced stud walls. Three typical wall configurations were defined according to both elastic and dissipative design criteria for three different seismic scenarios. The lateral in-plane inelastic behaviour of these systems was evaluated by twelve tests performed on full-scale Cold-formed strap-braced stud wall specimens with dimensions 2400 x 2700 m subjected to monotonic and reversed cyclic loading protocols. The experimental campaign was completed with seventeen tests on materials, eight shear tests on elementary steel connections and twenty-eight shear tests on strap-framing connection systems. This paper provides the main outcomes of the experimental investigation. Furthermore, the design prescriptions, with particular reference to the behaviour factor and the capacity design rules for these systems, have been proved on the basis of experimental results.

HIGHLIGHTS A critical analisys of design requirements for CFS strap-braced walls is discussed. The procedure for the evaluation of wall stiffness and resistance is illustrated. A case study involving the design of three residential buildings has been developed. 2 ABSTRACTThe use of cold-formed steel (CFS) profiles in low-rise residential buildings has increased in European construction sector. The reason of this interest is related to potentialities offered by this constructive system, which are the high structural performance, lightness, short construction time, durability and eco-efficiency. Nevertheless, the current structural codes, such as Eurocodes, do not provide enough information about the seismic design of this structural typology. In an effort to investigate the seismic response of CFS structures, a theoretical and experimental research has been carried out at University of Naples Federico II, with the main aim to support the spreading of these systems in seismic areas. This study focuses on an "all-steel design" solution in which strap-braced stud walls are the main lateral resisting system. In the present paper the outcomes of theoretical phase are shown with the aim of defining the criteria for the seismic design of such structures. In particular, a critical analysis of the requirements for CFS systems provided by the American code AISI S213 has been carried out by comparing it with those given by Eurocodes for traditional braced steel frames.

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