SEISMIC DESIGN AND EXPERIMENTAL RESEARCH ON NON-STRUCTURAL LIGHTWEIGHT STEEL DRYWALL BUILDING COMPONENTS

Recent earthquakes highlighted the high vulnerability of non-structural building components to relatively low seismic intensity levels. Their seismic damage could involve substantial economic losses, limit functionality interruption of the most affected buildings and pose a significant hazard to human life. Nevertheless, in the last decades, the study on the seismic response of non-structural building components has received less attention than the research addressed on the primary structural systems, by leading to a lack of specific design provisions for these systems. These considerations highlight that the development of protection measures aimed to reduce the seismic risks and to manage the vulnerabilities of the non-structural building components is becoming one of the most critical issues of the current seismic design. The importance of a rational concept of non-structural building components has also been recognized in the developments of modern seismic regulations, through the introduction of specific design requirements in terms of strength and deformation for these elements. However, the knowledge of their seismic performance is still poorly understood. Since the ceiling-partition walls systems represent a significant investment in the construction market, the current trend of the construction sector aims to the development and promotion of innovative solutions also in the field of non-structural applications. In this framework, lightweight steel drywall building components represent a valid alternative to traditional non-structural systems in seismic areas, by guaranteed a good seismic behaviour with respect to damage limit states mainly thanks to their lightness and low stiffness. However, since the behaviour of non-structural lightweight steel drywall building components cannot be easily simulated with traditional analysis methods, the experimental characterization is an effective procedure. For these reasons, an important collaboration between an industrial company and the University of Naples Federico II was established over the last few years. The main objective of the research is to investigate the seismic performance of non-structural lightweight steel drywall building components, also considering the design requirements provided in the modern seismic code for non-structural elements. The main aim of this dissertation is to give a contribution to the investigation of the seismic performance of lightweight steel gypsum board partition walls and their interaction with other non-structural and structural components, i.e. exterior walls and surrounding structural elements. In particular, two main objectives are pursued in this work: the study of the seismic behaviour of drywall partition walls, in terms of global response, by means of full-scale out-of-plane and in-plane experimental tests; and the study of local behaviour, by means of tests on main material and components, for understanding their influence on the wall global seismic response. Results obtained by material, component and connection tests will be useful for characterizing the local mechanical behaviour of the investigated systems and for predicting their global seismic response through suitable numerical studies. Furthermore, the experimental assessment of the wall global seismic response will provide seismic design criteria by testing to be compared with the design requirements provided in the European code

Shake Table Testing for Seismic Response Evaluation of Cold-Formed Steel-Framed Nonstructural Architectural Components

The seismic response evaluation of cold-formed steel-framed nonstructural architectural components was investigated in an experimental campaign carried out within of the research study agreement between Knauf Gips KG and the Department of Structures for Engineering and Architecture of the University of Naples “Federico II”. The main objective of this research was to investigate the seismic performance of drywall nonstructural systems, i.e. cold-formed steel-framed indoor partition walls, outdoor façade walls and suspended ceilings. The present paper deals with the dynamic shake table tests. The tests were carried out on two different typologies of prototypes (Type 1 and Type 2) for a total number of five specimens. The influence on seismic response of basic and enhanced anti-seismic solutions, corresponding to the use of fixed or sliding connections at the walls and ceilings perimeter, was investigated. The seismic response evaluation of the systems under investigation has been performed according to ICBO-AC156 code with different levels of increasing intensity. Test results have been analysed in terms of dynamic identification, dynamic amplification, and fragility curves. Test results highlight that enhanced solutions have a better seismic response than basic solutions and indoor partition walls have a higher seismic “fragility” than outdoor facade walls

Evaluation of the Seismic Performance of Light Gauge Steel Walls Braced with Flat Straps

The 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 carried out at the University of Naples within the research project RELUIS-DPC 2010-2013. The study focused on all steel design solutions and investigated the seismic behaviour of strap braced stud shear walls. Three wall configurations were defined according to both elastic and dissipative design criteria for three different seismic scenarios. The lateral in-plane behavior of these systems were evaluated by 12 tests performed on full-scale CFS strap-braced stud wall specimens with dimensions 2.4 m x 2.7 m subjected to monotonic and reversed cyclic loading protocols. The experimental campaign was completed with 17 tests on materials, 8 shear tests on elementary steel connections and 28 shear tests on strap-framing connection systems. On the basis of the experimental results, and taking into account the AISI S213 provisions, behaviour factors were evaluated. This paper provides the main outcomes of the experimental tests on walls and behaviour factors evaluation

Experimental Tests for the Seismic Response Evaluation of Cold-Formed Steel Shear Walls Sheathed with Nailed Gypsum Boards

The European project named Energy Efficient LIghtweight-Sustainable-SAfe- Steel Construction (Project acronym: ELISSA) is devoted to the development and demonstration of cold-formed steel (CFS) modular systems. In particular, these systems are nano-enhanced prefabricated lightweight steel skeleton/dry wall construction with improved thermal, vibration/seismic and fire performance, resulting from the inherent thermal, damping and fire spread prevention properties. The different building performances are studied and improved by means of experimental and numerical activities organized on three scale levels: micro-scale, meso-scale and macro-scale. In particular, the evaluation of the seismic performance is carried out at the University of Naples by means tests on connections (micro), seismic-resistant systems (meso) and full-scale two stories house prototype (macro). From a structural point of view, the system is a sheathed-braced CFS solution, in which the seismic resistant elements are made of CFS stud shear walls laterally braced by gypsum-based panels. In the adopted solution, the sheathing panels are attached to the CFS frame by means of ballistic nails, whereas clinching points are used for steel-to-steel connections. The present paper illustrates the results of meso-scale tests performed on four full scale shear walls, in which the influence of the aspect ratio, the type of loading and the effect of finishing was investigated

Seismic response of Cfs strap-braced stud walls: Experimental investigation

The 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 behavior 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 behavior of these systems was evaluated by twelve tests performed on full-scale Cold-formed strap-braced stud wall specimens with dimensions 2400×2700 m2 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 behavior factor and the capacity design rules for these systems, have been proved on the basis of experimental results

Seismic response assessment of architectural non-structural LWS drywall components through experimental tests

A research project was conducted at University of Naples “Federico II” over the last few years with the aim to give a contribute to overcome the lack of information on seismic behaviour of architectural non-structural lightweight steel (LWS) drywall components, i.e. indoor partition walls, outdoor façades and suspended continuous ceilings. The tested non-structural components were made of LWS frames sheathed with gypsum-based or cement-based boards. The research activity was organized in three levels: ancilliary tests, component tests and assembly tests. Ancilliary tests were carried out for evaluating the local behaviour of partitions, façades and ceilings. Component tests involved out-of-plane quasi-static monotonic and dynamic identification tests and in-plane quasi-static reversed cyclic tests on partitions. Finally, the dynamic behaviour was investigated through shake table tests on different assemblages of partitions, façades and ceilings. The study demonstrated that the tested architectural non-structural LWS drywall components are able to exhibit a very good seismic behaviour with respect to the damage limit states according to the IDR limits given by Eurocode 8 Part 1. The current paper describes the complete experimental activity within the project

Out-of-plane seismic design by testing of non-structural lightweight steel drywall partition walls

Seismic damage of non-structural components could involve functionality interruption of the most affected buildings and substantial economic losses. Among non-structural components, the ceiling-partition wall systems represent a significant investment in the construction sector. Nevertheless, the seismic design of these systems plays a secondary role within the structural design, by leading to a lack of specific design provisions. Because the behaviour of these systems cannot be easily simulated with traditional analysis methods, the experimental characterization is an effective procedure. For these reasons, an important collaboration between an international company and the University of Naples Federico II was established over the last few years. The main objective of the research is to investigate the seismic performance of non-structural lightweight steel drywall building components, i.e. partition walls and suspended continuous ceilings made of lightweight steel profiles and sheathed with gypsum-based panels. The presented paper describes and discusses particularly the out-of-plane quasi-static monotonic tests and dynamic identification tests carried out on lightweight steel drywall partition walls, mainly devoted to develop the seismic design criteria by testing of these system

Design and numerical simulation of shake-table tests of CFS strap-braced stud structures

The unconventionality of the cold-formed steel (CFS) structures raised, in recent times, a lot of interest from many national and international companies resulting in the promotion of ex-perimental activity with the main aim of investigating the seismic behaviour of these systems. In this perspective, an important cooperation between the University of Naples “Federico II” and Lamieredil S.p.A. company started in the last years. The research project included an ex-tended experimental campaign, involving shake-table tests on two three-storeys prototypes in reduced scale (1:3). The investigated seismic-resistant systems were CFS strap-braced stud walls, designed as low dissipative. The present paper illustrates the design of prototypes and the development of a numerical model with OpenSees software for the simulation of seismic response