GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 2.2 310 ANALYTICAL FRAGILITY METHOD TO ASSESS SEISMIC BEHAVIOUR OF GLASS PANELS S. Mattei 1,* , C. Bedon 1 1 University of Trieste, Department of Engineering and Architecture, Trieste, Italy 1 Background In the last century, given the increased demand for concrete, steel and masonry as building materials, the development of regulatory codes and guidelines has mainly affected those structural systems, neglecting “innovative” materials such as glass. In the 1960s, with the birth of structural silicone as a connecting element between the frame and the glass panel, fully glazed facades became a predominant element in new constructions. Given, however, the characteristic fragility of glass when designing structural glass, it is necessary to identify all the actions, the responses of the individual components and how they interact each other. Although there are many glass structural systems made in recent years, the most important question regarding the structures built with this construction typology is their behaviour under seismic loads. The main requirement in a seismic design is the safeguarding of human life. The correct design of glass buildings plays an important role in terms of comfort. Galli (2011) in his doctoral thesis compared the seismic forces acting on the façade systems for the various normative codes, describing the differences between the various formulations. A similar work to the previous one was carried out by Caterino et al. (2017). In particular, the widespread use of façades encourages researchers to focus on their seismic response, demonstrating the need in developing reliable methods to characterize the in-plane and out-of-plane performance, and in presenting a complete Finite Element modelling protocol. Recently, although glazing system are commonly considered as non-structural elements, several studies have shown their contribution to the overall structural behaviour of the building. Especially in high-rise buildings with a uniform and modular arrangement of the outer glazing surfaces, there was, in fact, a participation in the structural stability, resistance and dissipation of the dynamic load. The main objective of this work is to assess the seismic structural response of a single glass panel in terms of vulnerability curves in order to provide a tool for performance-based earthquake engineering (PBEE). In this field, O’Brien et al. (2012) derive fragility curves by means an experimental program on different glass configurations. 2 Case study 2.1 Geometrical properties The present work is intended to provide a numerical approach to develop analytical fragility curves, supported by FE investigations. The behaviour of curtain walls under seismic action has been widely discussed, but it continues to be increasingly relevant. The current research study considers a glass panel spanning between floors (B x H = 1 x 3.5 m) with two-sided silicone system ( Fig.1.Geometry of (a)frame-supported glass panel neglecting contribution of mullions and (b) detail of base connectio n). The cross-section is composed of two tempered layers and a Polyvinyl Butyral (PVB) foil. In accordance with Mocibob (2008) and the extended investigation in Amadio and Bedon (2016), the adopted scheme is characterized by the presence of four unilateral steel supports tasked with transferring the compressive reaction forces and avoiding excessive tension