GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 also restraining the upper masonry curb thanks to the inclined links and the tensile resistance of the steel frame. Note that the frame, reported in Fig. 3b, has been designed to remain linear elastic under the action of "Irpinia 1980" earthquake (Boni and Royer-Carfagni, 2023); also the glass pane has been designed to remain sound under the seismic action. In conclusion, an infill masonry wall, acting as additional shear wall, is effective, but this traditional technique has a strong visual impact and can be damaged during the earthquake. Indeed, it is massive and opaque, therefore not acceptable from an aesthetic point of view. On the contrary, a glass-based diaphragm is slender and transparent, provides strength and stiffness, and can be designed to remain linear elastic (sound and undamaged) during the seismic shakes, leaving the structure immediately usable after the earthquake. Final remarks We have presented a comparison between a traditional and an innovative seismic retrofitting technique, applied to the case study of an arcade gallery. The traditional retrofitting consists of massive additional infill walls in order to strengthen the later buttresses of the colonnade; the innovative solution uses a transparent glass-based bracing composed of a glass pane surrounded by a thin steel frame, which hoops the glass providing a restraint against the pane rotation and furnishes suitable anchoring points to connect it to the ground and to the masonry. The numerical simulations to assess the seismic response of the masonry structure were performed with a DEM software in order to take into account the role of the actual stereotomy and brick pattern. The glass-based bracing outperforms the traditional retrofitting work, as it is stiff and transparent, and the steel frame is slender for minimal visual impact. The element is prefabricated and can be easily inserted/removed in the structure. Moreover, it remains sound and undamaged after the considered earthquake. Anyway, there are limitations in the present study that still require additional investigations: we have analysed only a specific case study under one seismic event; the glass-based bracing was considered only in the linear elastic phase, thus neglecting the post-glass-breakage capacity and stiffness reduction; the construction details are at the level of concept schematic. Nevertheless, we repute that the example here proposed can represent a benchmark problem to appreciate the great potential of transparent glass-based systems for seismic retrofitting of historical buildings, if compared to traditional, more invasive, techniques. References Boni C. and Royer-Carfagni G; 2023: Transparent hybrid glass-steel bracing to improve the seismic capacity of historic buildings with colonnades. Engineering Structures 278, 115522.D'Amico M, Felicetta C, Russo E, Sgobba S, Lanzano G, Pacor F, et al.; 2020: Irpinia 1980. Italian Accelerometric Archive v 3.1 - Istituto Nazionale di Geofisica e Vulcanologia, Dipartimento della Protezione Civile Nazionale