GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 2.2 373 numero delle vittime fornendo così dati affidabili e facilmente utilizzabili per il calcolo degli scenari di perdite. Bibliografia Locati M., Camassi R., Rovida A., Ercolani E., Bernardini F., Castelli V., Caracciolo C.H., Tertulliani A., Rossi A., Azzaro R., D’Amico S., Conte S. and Rocchetti E.; 2016 : DBMI15, the 2015 version of the Italian Macroseismic Database. Istituto Nazionale di Geofisica e Vulcanologia. doi:10.6092 /INGV.IT -DBMI15 Rovida A., Locati M., Camassi R., Antonucci A., Bernardini F., Caracciolo C.H. and Maffezzoni L; 2017: L’archivio storico macrosismico italiano (ASMI). Gruppo Nazionale di Geofisica della Terra Solida, 36° Convegno Nazionale, Riassunti estesi delle comunicazioni. Trieste, pp. 255-258. Rovida A., Locati M., Camassi R., Lolli B. and Gasperini P. (eds); 2016: CPTI15, the 2015 version of the Parametric Catalogue of Italian Earthquakes. Istituto Nazionale di Geofisica e Vulcanologia. doi:10.6092 /INGV.IT -CPTI15 VULNERABILITYASSESSMENTANDDYNAMICCHARACTERISATIONOFAGLASS FOOTBRIDGE: ON-SITE VIBRATION TESTS AND FE NUMERICAL MODELLING C. Bedon University of Trieste, Department of Engineering and Architecture, Trieste, Italy Introduction. In the last decades, the use of glass as a load-bearing material showed an exponential increase, both on the side of projects and research studies. Although it represents a relatively new construction material, requiring appropriate design methods and knowledge, glass is largely used for facades, roofs, footbridges. Given a series of intrinsic features, special care should be spent at the design stage, to ensure appropriate fail-safe requirements, but also in the life-time of these structures (Haldimann et al. 2008). The brittle behaviour and limited tensile resistance of glass, as well as the typical high flexibility of glazing assemblies, represent the major issues. Further critical aspects may derive from time and ambient effects, due to the sensitivity of glass-related materials and components to long-term loads, humidity, fatigue, etc., or extreme loads. The vulnerability assessment of glazing systems under exceptional loads (seismic events, fire, etc.) is hence an open topic, still requiring huge efforts. In this paper, the preliminary dynamic characterisation of an existing glass suspension footbridge is presented. As a case-study, the walkway of the Basilica of Aquileia (UD) is taken into account. On-site vibration experiments are discussed, to estimate the fundamental parameters of the structure. A Finite Element (FE) numerical study is then carried out, to further assess and explore the walkway performance. Case-study. The Basilica of Aquileia, listed by UNESCO as a World Heritage Site, includes the largest and one of the best preserved early Christian mosaics, and attracts over than 300,000 visitors every year. The suspension walkway object of study was realised in the early 2000, as a key strategy to protect the mosaics and allow for their visibility. The original design concept was aimed at maximising the transparency of the footbridge, hence minimising its impact on the Basilica context. A total of 118 glass panels was used (79 in the central nave and 39 in the crypt). In structural terms, the footbridge was assembled via a glass roof, a set of steel frame members and suspension tendons, and steel-glass handrails (Fig.1(a)). More in detail, each roof panel consists of a triple laminated glass (LG) section, obtained by bonding fully tempered (FT) layers (3×12mm the thickness) via flexible Polyvinyl Butyral films (PVB®, 0.76mm thick). An additional protective layer, composed of annealed (AN) glass (6mm) was also accounted on the LG panels, so as to preserve their integrity under antropic loads. No mechanical connection was considered between the LG-AN layers, however, with contact interactions only. A small,