The most recent trends in the design of steel buildings favour transparency, lightness and aerial effects, by including large glass facades, increasing the free spans of floors and roofs, and implementing innovative architectural shapes and finishes. These emerging trends compel structural designers to reduce the architectural impact of the load-bearing systems further, while at the same time meeting the high levels of performance required to steel constructions by the last generation of technical and seismic Standards. This is especially true for buildings designed in medium-to-high seismicity zones, for which a satisfactory balance between the issues of structural performance and limited architectural impact represents a truly demanding challenge for designers.

Effective solutions are currently offered by the advanced seismic protection technologies available in the market of building industry. Among these technologies, dissipative bracing systems generally provide the most viable solutions for steel buildings, as they resemble the bracing strategies traditionally incorporated in steel structural skeletons to absorb seismic and wind loads. This allows keeping substantially unchanged the classical set-ups of steel structures and at the same time, drastically reducing the member dimensions and/or the number of locations where braces must be placed, thanks to the remarkable reduction of seismic effects warranted by the damping action of dissipaters.

Within the wide class of dissipative bracing technologies, a special system incorporating pressurized fluid viscous devices was studied by the authors for several years, paving the way to its practical application to new and existing frame structures.

The development of demonstrative case studies for both types of designs is among the aims of the programme of the Unit of the University of Udine within Task 2.3.2 of ReLUIS-DPC 2010/2013 Research Project, began on July 2010. A novel and highly demanding application for new structures, concerning a steel gym building well representative of the above-mentioned architectural design trends, is presented in the paper submitted for possible participation to the XIV ANIDIS Conference. The building is characterized by a single span roof and open space-type interiors, a continuous structural glass façade, and a perimeter arcade. Furthermore, the architectural design also imposes slender internal and external columns and, in general, very compact sizes of structural members.

The paper will include: a summary of the characteristics of the protective system; a detailed description of the selected case study, including the preliminary and final verification design phases, with a synthesis of the non-linear dynamic analyses and seismic performance evaluations carried out; a comparison with the performance, aesthetical appearance and costs of two traditional anti-seismic designs of the building, complimentarily developed to precisely assess the advantages of the protection solution adopted; and finally, structural, architectural and finishing details concerning the installation of the system.