Advanced seismic retrofit of a low-rise R/C building

The paper offers a synthesis of the design study of an advanced seismic retrofit solution of a low-rise reinforced concrete building, consisting in the installation of a dissipative bracing system incorporating pressurized fluid viscous spring-dampers as passive protective devices. This demonstrative application represents the last stage of the research activities carried out by the authors on this protection technology, also within several international Research Projects. The structural characteristics of the case study building make it representative of a large stock of similar edifices designed with earlier Technical Standards editions, in Italy and other European seismic-prone countries. The mechanical parameters, dimensions, layouts and locations selected for the constituting elements of the system, and the performance assessment analyses in original and rehabilitated conditions carried out according to a full non-linear dynamic approach, are presented. The results of the analyses show a remarkable enhancement of the seismic response capacities of the structure, which allows reaching the high performance levels postulated in the retrofit design

The damped cable system for seismic protection of frame structures - Part I: General concepts, testing and modeling

Research studies on the damped cable system (DCS) for seismic protection of frame structures are presented in this paper and the accompanying one. This technology includes prestressed steel cables linked to pressurized fluid viscous spring-dampers fixed to the foundation at their lower ends, and to the top floor, or one of the upper floors, at their upper ends. The cables have sliding contacts with the floor slabs, to which they are joined by steel deviators. The general characteristics of the system, as well as of the constituting spring-dampers and cables, are initially discussed. The results of a laboratory testing campaign developed on a DCS prototype are examined, and transferred into the formulation of the finite element model of the system, conceived to be easily generated by commercial structural analysis programs. A second dynamic experimental investigation follows, concerning a pilot installation of the system on a full-scale mock-up building. The benefits of the protective technology are evaluated in terms of maximum displacements and accelerations, as well as of equivalent viscous damping coefficient and MDOF transmissibility ratio. Further sections of the study, including a preliminary sizing criterion of DCS, additional numerical enquiries aimed at optimizing its geometrical layout, and the application to a real case study building, are offered in the companion paper. \ua9 2011 John Wiley & Sons, Ltd

Analysis, design, and construction of a base-isolated multiple building structure

The analysis and design of a multiple residential building, seismically protected by a base isolation system incorporating double friction pendulum sliders as protective devices, are presented in the paper. The building, situated in the suburban area of Florence, is composed of four independent reinforced concrete framed structures, mutually separated by three thermal expansion joints. The plan is L-shaped, with dimensions of about 75 m in the longitudinal direction and about 30 m along the longest side of the transversal direction. These characteristics identify the structure as the largest example of a base-isolated “artificial ground” ever built in Italy. The base isolation solution guarantees lower costs, a much greater performance, and a finer architectural look, as compared to a conventional fixed-base antiseismic design. The characteristics of the building and the isolators, the mechanical properties and the experimental characterization campaign and preliminary sizing carried out on the latter, and the nonlinear time-history design and performance assessment analyses developed on the base isolated building are reported in this paper, along with details about the installation of the isolators and the plants and highlights of the construction works

Analysis, testing, design and construction of a base isolated/supplementally damped building

The first actual application to a demonstrative strategic building of a special base isolation/supplemental damping system, where fluid viscous spring-dampers are coupled to steel-Teflon sliders, is presented in this paper. The results of a testing campaign aimed at assessing the interference of the dissipative actions of the two component devices, as a final step of the research studies previously developed by the authors on this technology, are summed up. The design and performance evaluation analyses carried out on the building are then discussed. Highlights of the construction works and technical installation details are finally illustrated