Study of wire rope devices for improving the re-centering capability of base isolated buildings Mariacristina Spizzuoco 1, * ,† , Virginio Quaglini 2 , Andrea Calabrese 1 , Giorgio Serino 1 and Claudia Zambrano 1 1 Department of Structures for Engineering and Architecture, University of Naples Federico II, Naples 80125, Italy 2 Department of Architecture, Built Environment and Construction Engineering, Politecnico di Milano, Milan 20133, Italy SUMMARY Wire rope devices have found numerous applications in the shock and vibration isolation of industrial machinery and equipment. The aim of the work is to present a preliminary investigation of their usefulness as a mean to in- crease the re-centering capability of the isolation system of a civil structure. In the first part of the study, analytical formulations have been developed to predict the restoring stiffness of wire rope devices depending on their material and geometrical properties, and the direction of loading. In the second part, a preliminary assessment of wire rope springs has been performed based on unidirectional shake table tests on a scaled steel structure isolated with curved surface slider and either or not provided with wire rope springs. The changes in the seismic response of the isolation system are analyzed and some suggestions for improving the use of wire rope devices are drawn. Copyright © 2016 John Wiley & Sons, Ltd. Received 21 July 2015; Revised 9 March 2016; Accepted 19 July 2016 KEY WORDS: wire rope devices; base isolation; shake table; buildings; seismic 1. INTRODUCTION Wire rope isolators consist of mounting assemblies made of a twisted stranded stainless steel cable wound in helical shape and held between metal retainers [1]. These devices provide the fundamental properties required to isolation hardware into a single, cost-effective product: flexibility in three per- pendicular directions and large displacement capacity thanks to the helix cable arrangement, inherent damping resulting from friction among the strand wires, and a spring restoring force proportional to the deflection; other valuable properties are high stability against chemical and environmental agents, no need for maintenance, and resistance to extreme temperatures deriving from the fully metal design. The main limitation to the use of wire rope isolators is related to their low vertical load capacity. Wire rope isolators were originally designed for military applications but have become increasingly popular in the industrial sector, for the protection of shipboard equipment, electronic racks, shipping containers, avionics, and railway equipment. The usefulness of wire rope systems for the protection of sensitive equipment in buildings and industrial facilities has been assessed in several investigations. Demetriades et al. [2] studied the performance of wire ropes for seismic protection of single slender items of equipment which are attached to vibrating floors. The equipment isolated with wire ropes was subjected on a shake table to floor excitation determined by filtering recorded earthquake motions through a real seven-story building, finding a substantial reduction of the acceleration transmitted to the *Correspondence to: Mariacristina Spizzuoco, Department of Structures for Engineering and Architecture, University of Naples Federico II, Naples, Italy. † E-mail: spizzuoc@unina.it STRUCTURAL CONTROL AND HEALTH MONITORING Struct. Control Health Monit. (2016) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/stc.1928 Copyright © 2016 John Wiley & Sons, Ltd.