We gradually emerge from two difficult years of the covid-19 pandemic raging through the world in waves of constantly changing intensities. The associated uncertainties really put the ‘challenging’ into Challenging Glass this time. Still, some of our peers are not able to join us in Ghent, and they will be sorely missed. Nevertheless, we are happy to be able to return this year to the ‘real thing’: a live event which allows the international glass community to finally meet again in person. An excellent opportunity, especially within the UN-declared International Year of Glass 2022. We look forward to reconnect with international colleagues and old friends, but we also want to extend a particularly warm welcome to new and young peers who perhaps have not yet had many opportunities to build their professional network.

Editorial

Editorial

Editorial

Editorial

This chapter on architectural glass focuses on the use of glass in buildings and structures. It covers a wide variety of glass applications ranging from its most frequent use in facade glazing systems to advanced applications of glass as a load-bearing material. The latter is a relatively young field of application and evolved from the early 1990s from simple beam applications to today's all-glass structures. An overview of flat glass products that are frequently applied in architecture is provided in Sect. 52.1. This includes a discussion of the related float glass production process, processing technologies, surface treatments, and glass functionalities such as insulation and fire resistant and switchable glazing. In addition to these flat glass products, which are most commonly applied in architecture, Sect. 52.2 discusses cast glass products. Cast glass products such as glass channels and glass blocks provide a different typology and offer a different architectural expression from flat glass products and are as such frequently used in exterior facades and interior separation walls. The application of glass in common facade systems and as a load-bearing material in structures is discussed in Sect. 52.3. This includes a reflection on the related design methodologies and safety concepts that deal with the brittle and, thus, inherently unsafe failure behavior of glass. Section 52.4 describes different typologies for connecting glass components such as glass facade panels or structural glass beams. This includes a discussion of classical mechanical connections and more recent adhesive bonding technologies that provide new opportunities for glass engineering. Section 52.5 discusses numerical modeling procedures that can be used in the design and engineering of glass in the architectural domain. Finally, an outlook for future developments in architectural glass is provided in Sect. 52.6.

Editorial

Editorial

This paper presents a study on post-tensioned glass beams in a statically indeterminate system. In order to increase the safety of structural glass beams, ductile reinforcement can be added to glass beam sections providing secondary load carrying mechanism in case of glass breakage. In the here investigated post-tensioned system, the reinforcement tendons are additionally pre-tensioned, introducing compressive pre-stress in the beam in order to increase the apparent tensile strength of glass. The system is tested in five-point bending at 23°C and 60°C in order to investigate the basic structural performance and the influence of temperature increase on the initial cracking load and the behaviour of the cracked beam. The benefit of the here investigated statically indeterminate system is a more economical design, i.e. lowering of the bending moment in the span of an equivalent simply supported system by continuing the beam over the central support. The efficiency of the applied system is compared to a reinforced beam system produced in the same batch with similar overall dimensions. The results show an increase of initial cracking load of the post-tensioned beams due to the applied pre-stress and a ductile post-cracking response, reaching high ultimate loads prior to failure. At 60°C both reinforced and post-tensioned beams show lower initial cracking loads and limited post-cracking ductility but still significant load reserve with ultimate loads well above the initial cracking loads, providing safe failure behaviour.