Numerical fragility assessment and structural performance analysis of glass facade systems including post-fracture residual capacity

In modern civil engineering the ability to adopt models for the assessment of the seismic vulnerability of structures, especially for structures consisting of materials whose design is still characterized by a huge amount of uncertainties, is an important means for the assessment of seismic risk and therefore for the mitigation of losses due to stochastic events. Glass as a building material has always been an integral part of structures for aesthetic/functional purposes only such as to bring light to environments or to provide ventilation to them. In recent years, due to the development of new technologies for the production of glass elements, civil engineering has given space to the construction of structural works consisting entirely of glass. Until a few decades ago, it was impossible to think of entrusting brittle elements the load-bearing capacity, therefore it only served as a frame to the design. However, although today there is greater awareness of the use of this material, the design criteria for these types of construction are still lacking. And in particular, there is no way in the calculation codes of the whole world to predict the inter-storey displacement that can cause the achievement of a specific damage state of glass systems. Thus, it is impossible to define the structural damage thresholds for particular limit states. The main objective of this thesis is therefore to provide means and solutions related to increasing the reliability of these structures, and in particular for façade systems against seismic action. In this thesis, the first results are presented in terms of fragility curves, built with a numerical approach on glass panels and overall buildings obtained by means of post-processing cloud analysis results, using non-scaled seismic records on FE models (built in Abaqus/CAE) inspired by scientific literature, providing a comparison with an analytical and experimental approach. The Cloud analysis is simpler than the method characterized by incremental dynamic analysis (IDA) because the latter has climbed to the collapse of the structure and therefore burdens a greater computational effort. In particular, the considered models were chosen because representing a wide range of existing solutions in the context of glass constructions, exposing the results for several types of structural glass (monolithic and laminated) and various configurations (in terms of glass-to-frame clearance). In detail, the results obtained from the non-linear analyses were analysed using linear regression analyses, through the application of a Maximum Likelihood Estimate, assuming a constant standard deviation. Finally, this work focuses on some peculiar issues in using PET films on glass panels. In the structural field, they are mainly used to reduce the risks related to the fragmentation of glass following sudden and exceptional events such as seismic events; explosions, and impacts. In particular, the material characterization of the commercial multilayer product used in the conducted experimental campaign and the following study of the influence that these safety sheets offer on the bending mechanical response of glass, are addressed by combining the experimental results with the calibration analyses carried out by a three-dimensional model in a FE software (such as Abaqus/CAE). This last step allows stating the adhesion parameters, such as the fracture energy, G, using a typical cohesive zone model (CZM) taking into account the influence of displacement-rate and ageing protocols.