Challenging Glass Conference Proceedings
Challenging Glass Conference Proceedings collects the conference articles presented at the international bi-annual Challenging Glass Conference and focuses on the Architectural and Structural Application of Glass.
Platinum Sponsor Saint-Gobain Gold Sponsors Eastman Kuraray sedak Silver Sponsors Dow Octatube Permasteelisa Group
Copyright (c) 2024 Challenging Glass https://creativecommons.org/licenses/by/4.0
Keynote Speakers Dr Faidra Oikonomopoulou – Delft University of Technology Dr Telesilla Bristogianni – Delft University of Technology Alexandros Cannas, Dipl.-Ing. CEng MICE – Eckersley O'Callaghan Dr Peter Zoon – Netherlands Forensic Institute Prof. Corentin Fivet – Structural Xploration Lab - EPFL
Conference Organisers Prof. Christian Louter – Delft University of Technology Dr Freek Bos – Technical University of Munich Prof. Jan Belis – Ghent University Conference Co-Hosts Prof. James O'Callaghan – Delft University of Technology Prof. Mauro Overend – Delft University of Technology Dr Fred Veer – Delft University of Technology Conference Support Deborah Dekker – Delft University of Technology Noor van Geffen – Delft University of Technology Rens Hoekstra – Delft University of Technology Lukas Huber – Delft University of Technology Laura Jurić – Delft University of Technology Hrishika Rastogi – Delft University of Technology Sandra Schuchmann-Hagman – Delft University of Technology Jacqueline van Unen-Bergenhenegouwen – Delft University of Technology Iris Nederhof-van Woggelum – Delft University of Technology Scientific Committee Dr Chiara Bedon – Trieste University Prof. Jan Belis – Ghent University Prof. Lucio Blandini – University of Stuttgart Dr Freek Bos – Technical University of Munich Dr Telesilla Bristogianni – Delft University of Technology Prof. Suwen Chen – Tongji University Prof. Paulo Cruz – University of Minho Dr Jagoda Cupać – Technische Universität Dresden Dr Corinna Datsiou – University of Hertfordshire Dr Martina Eliášová – Czech Technical University in Prague Prof. Michael Engelmann – Technische Universität Dresden Prof. Steffen Feirabend – Hochschule für Technik Stuttgart Prof. Markus Feldmann – RWTH Aachen Dr Laura Galuppi – University of Parma Dr Rebecca Hartwell – Delft University of Technology Prof. Christian Louter – Delft University of Technology Dr Stephen Morse – Michigan Technological University Prof. Jürgen Neugebauer – FH Joanneum Dr Jens Henrik Nielsen – Technical University of Denmark Prof. James O'Callaghan – Delft University of Technology Dr Faidra Oikonomopoulou – Delft University of Technology Prof. Mauro Overend – Delft University of Technology Prof. Jens Schneider – Technische Universität Wien Prof. Christian Schuler – Munich University of Applied Sciences Dr Miriam Schuster – Technische Universität Darmstadt Dr Vlad Silvestru – ETH Zurich Dr Bert Van Lancker – Ghent University Dr Fred Veer – Delft University of Technology
Welcome at Challenging Glass! At this 9th edition of the conference, we are thrilled to welcome no less than 120 presentations - a record since the first edition of this international event back in 2008. Ever since, we have been keeping up our high standards in sharing knowledge, science and best practices on glass engineering and design. Thanks to the great work of bright authors and sharp reviewers, that is not different this time. What actually ís different this edition, is the introduction of a Glass Circularity Debate. We have seen several trends come and go over the past years, but the importance of circular design is to stay! Therefore, on top of the regular technical sessions on the topic, we bring five speakers to the stage who will pitch their views on the circular use of glass and discuss it with each other and the audience. You are warmly invited to actively participate! Furthermore, we are happy to welcome no less than five top-notch keynote speakers. The first keynote will focus on the Mirage project and will be delivered jointly by Dr Faidra Oikonomopoulou, Dr Telesilla Bristogianni and Mr Alexandros Cannas. The second keynote will be presented by Dr Peter Zoon, who will explain how glass plays an important role in crime scene investigations. It promises to be a criminal talk! Last but not least, Dr Corentin Fivet will share his work on new design paradigms for reuse during his closing plenary lecture. During the conference you will be able to retrieve all abstracts and papers, but also presenter details and programme updates with our conference app. After the conference, all papers will be available online, either through our online proceedings platform or through the peer-reviewed journal Glass Structures & Engineering (SpringerNature). We explicitly like to thank the continuous support of our sponsors, Scientific Committee members, authors and attendees. Together with you and with our co-hosts James O’Callaghan, Mauro Overend and Fred Veer we are eager to kick off Challenging Glass 9! Christian Louter, Freek Bos and Jan Belis June 2024
Copyright (c) 2024 Christian Louter, Freek Bos, Jan Belis https://creativecommons.org/licenses/by/4.0
The adoption of glass reuse in construction faces challenges due to higher costs and more perceived risks compared to new glass. This conflicts with the goal of a circular economy. To challenge this status quo, this article explores a hypothetical scenario where glass becomes a scarce commodity. What if the float glass production process ceases to exist due to energy resource depletion, raw material scarcity, or carbon budget constraints? In such a context, glass reuse will be crucial. This article discusses the design, logistics and quality related challenges of reusing float glass, including structural integrity and energy performance considerations. Additionally, this article investigates the potential for glass reuse by analysing ongoing and future research, supply-demand dynamics, innovative building design, the concept of the future glass factory, and the re-evaluation and promotion of regulatory frameworks. To promote glass reuse, the article emphasizes customization over standardization. Considering the diverse dynamics of projects, from high-rise buildings to terraced houses, and varying regional construction requirements, solutions must be specific and adaptable, rather than standardized.
Copyright (c) 2024 Gertjan Peters, Erwin Ten Brincke, Josefien Van der Laan Dijkhuis https://creativecommons.org/licenses/by/4.0
A Portable Technology for Measuring Haze Levels in Thick Laminated Glass Panels
Increasing security concerns and a trend towards larger glass panels are driving the adoption of thicker laminate glass panels in prominent architectural works worldwide. However, the polymeric materials used in these laminates can lead to haze, a detrimental optical defect that impairs transparency perception, particularly when used in thick, multi-layer laminates. This work presents a novel technology capable of accurately and robustly measuring haze in glass laminates of arbitrary thickness, based on using computer-vision to measure changes in contrast when viewing a standard mask through the material under controlled diffuse lighting conditions. Unlike previous approaches, this technology can be employed on installed glasses without requiring exposed edges for double-sided measurements, making it suitable for on-site work. The experimental evidence provided indicates that its precision and robustness are adequate for quality control.
Copyright (c) 2024 Guillermo Casas, Javier Marcipar, Adrian Betanzos https://creativecommons.org/licenses/by/4.0
Circularity of Existing Aluminium Unitised Curtain Wall Façades
This article presents the metric avoided carbon for the reuse of aluminium unitised curtain wall façades from a donor building in a receiving building. The metric is used to compare seven proposed circular reuse strategies, each showing a different gradation of reuse. Based on literature and reference studies, we identify those parts of the façade where reuse has the most impact and is technically feasible. The seven reuse strategies and the avoided carbon method are applied on a real case study building as donor project and a fictive building as receiving project. We conclude that reuse is technically feasible, saves carbon, and that the proposed metric can help to incentivize building owners and project developers to choose circular reuse.
Copyright (c) 2024 Rianne Teeuwen, Roel Schipper, Jagoda Cupać , Hans Jansen, Christian Louter https://creativecommons.org/licenses/by/4.0
Challenges in Phase-Field Modeling of Glass Fracture
This paper investigates the challenges and potentials of phase-field modelling in simulating glass fracture. The phase-field method, a variational approach to fracture modelling, treats cracks as diffused interfaces, thus eliminating the need for explicit crack tracking. This study explores its application to glass, a material with unique fracture characteristics due to its amorphous structure and brittleness. We implemented the AT1 phase-field model using Abaqus and validated it against various experimental setups, including micro-cantilever and micro-pillar tests, L-shaped samples, and dynamic tensile fracture scenarios. The results demonstrated strong alignment with experimental observations, accurately capturing complex crack patterns and dynamic fracture behaviours. Key parameters like the critical energy release rate and internal length scale were shown to significantly influence fracture simulation outcomes. While the phase-field method shows promise in advancing glass fracture mechanics, challenges remain in parameter sensitivity and integrating more sophisticated material models. This study highlights the method's current capabilities and points to future research directions for enhancing its applicability and efficiency in glass fracture simulations.
Copyright (c) 2024 Gergely Molnár https://creativecommons.org/licenses/by/4.0
Environmental Impact of Passive Smart Window Technologies
This paper draws attention to the environmental impact of passive smart windows, a novel high-performance glazing technologies that can change their solar transmittance to control the amount of solar gain, thus reducing cooling energy demand. Despite the large influence of building envelope technologies on overall embodied carbon in buildings, the environmental impact of passive smart windows has been inadequately addressed, with a dearth of numerical data on various impact categories beyond energy consumption and Global Warming Potential (GWP). While current literature focuses on the advantages of these technologies in terms of operational energy savings, other critical environmental considerations are currently missing. This paper aims to bridge the existing gap by introducing a novel framework for evaluating the broader environmental impact of passive smart windows through a multi-category LCA method. By analysing the life cycle of these technologies, including production, usage, and disposal, the research seeks to provide a holistic understanding of their contribution to sustainability. The framework is based on systematic literature review on current state-of-art approaches and Interviews with key stakeholders in the dynamic glazing value chain. Literature review and interview results are presented, and then the framework is demonstrated through a case study of a thermochromic technologies for an office building in the Netherlands. Preliminary results show the critical areas where improvements on the methods or on the performance of the technology are required for the achievement of holistically sustainable high-performing glazing.
Copyright (c) 2024 Paolo Matricardi, Marc Ottele, Christian Louter, Alessandra Luna Navarro https://creativecommons.org/licenses/by/4.0
Phase Field Fracture Model for Assessing the Load Bearing Capacity of Fractured Glass
The use of glass as structural material has highlighted the need for more reliable numerical approaches to analyze its mechanical behavior, especially in the accidental eventuality of fracture. Modelling the behavior of fractured laminated glass, in fact, is fundamental to assess the Post-Fracture load-bearing capacity. However, this is a highly challenging task because of the many interplaying factors, such as the viscoelastic and thermal-dependent behavior of the interlayer, the presence of a highly complex and variable crack pattern and the interaction among fragments. The objective of the present work is the development and testing of a robust numerical model that can naturally introduce the generated crack pattern into virtual specimens and manage the interaction among many fragments. The phase field fracture model is herein explored, by assigning the damage variable to fit the pre-existing crack pattern. Then, the specimen is loaded letting the phase field managing the fragments interaction. The dependence of the stress tensor with the damage variable is herein defined through the Cleavage-Deviatoric model, since it prevents fully damaged regions from transmitting tensile and shear stresses yet keeping their ability to bear compressive forces. Indeed, this model can asymptotically reproduce unilateral and frictionless contact conditions between the existing crack lips. Preliminary case studies are discussed to check the potentiality of the proposed approach.
Copyright (c) 2024 Mauro Corrado, Arturo Chao Correas, Giulio Ventura https://creativecommons.org/licenses/by/4.0
Structural Damping of Glazed Facades and Resulting Risk of Vibration under Along Wind Excitations
The authors investigate the dynamic factor dependency on the major wind excitation parameters, including mean wind velocity, turbulence factor and system dynamic properties, by means of the Single Degree of Freedom (SDOF) simplification. The reason of the research is the controversial limit stated in the EN1991-1-4:2005, set to 5Hz, which represents the minimum value of the system first natural frequency allowing to ignore dynamic amplification factors to incorporate into the equivalent static approach. While the largest part of the scientific community aims at reducing this value, to avoid additional useless reinforcements and checks, other researchers have identified testing conditions for which vibrations occurred even for natural frequencies up to 14Hz. The authors start from the analysis undertaken in their previous work, identifying damping as the decisive parameter. Differently from what is reported in several literature studies, working conditions of glazed façades result often in equivalent structural damping larger than the minimum values assumed in numerical calculations. By means of other experimental data, it will be shown that an indiscriminate reduction of the 5Hz limit would be probably unsafe. Recommendations will be given in order to run specific experimental investigations to solve the inconsistent literature experiences and to the address the limit in future standards in dependency on specific combinations of wind and system dynamic properties.
Copyright (c) 2024 Guido Lori, Giampiero Manara https://creativecommons.org/licenses/by/4.0
The brainwave of spray printing glass (SPG) emerged in September 2021 and has become a feasible way of applicating glass in thin layers in June 2022. The whole idea started from a sustainable motive: Can we use less material and less energy for glass elements? Based on the theoretical background of repairing old diesel engines, physical tries were made with acetylene torches blowing glass powder on a glass plate, fusing the glass powder particles to a glass panel. The first result of SPG was an opaque substrate on a transparent panel. From there on the Glass Competence Center was investigating the parameters color, transparency, interface and residual strength. Color and transparency seemed to be influenced by temperature, velocity, granulate, base material and more. This paper presents a feasibility study of spray printed glass on flat glass and shows results regarding the practical realization, pore distribution of the novel glass connections and microscopy. The current samples achieved size of 190 mm by 30 mm for soda-lime silicate glass and 200 mm by 85 mm for borosilicate glass. Larger sizes are possible and ask for investments in heat chambers, robot arms and associating torches. The dimensions of the samples can be scaled up. Spray printed glass can be used for new elements, but also to strengthen reused glass panels e.g. by making ribs. That makes spray printing glass a revolutionary product that has favorable prospects in applications in several markets.
Copyright (c) 2024 Matthias Seel, Erwin ten Brincke, Emanuel Nowak, Phillip Amir Chhadeh, Ulrich Knaack https://creativecommons.org/licenses/by/4.0
Glass handrail loading and design in the United States lags behind best practice in other parts of the world. Improvements are possible for the design load, residual capacity and damage-event loading, each of which could be based on occupancy. Neither static loading nor impactor testing accounts for the dynamic effects of sustained loading to handrails during crowd load events. Alternate configurations for improved robustness at similar size and cost are presented.
Copyright (c) 2024 Richard Green, Andrew Crosby https://creativecommons.org/licenses/by/4.0
Other than limited special cases, there is a lack of standards providing guidance on the design of structural glass in the United States and much of the world. This has resulted in an ad-hoc approach by cities (authorities having jurisdiction), architects, and engineers. This paper outlines the key aspects of designing with glass in a manner that has reliability and robustness consistent with other structural materials while recognizing the unique aspects of glass. This voluntary design manual is aimed at providing 4 consistent levels of risk in applications that allow Architects, Owners and Engineers to have an informed decision-making process for selecting levels of robustness, which may or may not be otherwise required by code. The document aims at developing consistent practices to facilitate confident design in glass while also addressing a number of technical challenges.
Copyright (c) 2024 Richard Green, Andrew Crosby, Terrence McDonnell https://creativecommons.org/licenses/by/4.0
Design and Stability of Laminated Glass Beams and Cantilevers with Continuous Lateral Silicone Restraint
The stability of monolithic glass beams is reasonably well defined; as an elastic material it behaves in a similar manner to other elastic materials such as steel, for which there are many equations of different forms which give similar results. Special care is required for continuous restraint to the tension ﬂange. Equations presented in Australian Standard AS1288 Glass in Buildings – Selection and Installation have been used successfully for many years for monolithic fins when used with the strength model of AS1288 but require a more comprehensive approach when using laminated fins and/or strength models that allow higher levels of stress. A review of equations for cantilevers results in a wider range of approaches with significant variance between the outcomes of various published steel and glass standards. AS1288 has been used as the default standard for stability of glass fins, however for cantilevers it appears to have a misprint which has existed for decades. This paper presents strategies for determining the moment capacity of beams and cantilevers made of laminated glass with continuous flexible buckling restraints, such as structural silicone, which have initial imperfections and a known design strength capacity. Where multiple wave lengths form, the warping stiffness may contribute and formulations for rectangles are presented. The accuracy and validity of the approach is also assessed by means of comparisons with the outcomes of Finite Element numerical analyses.
Copyright (c) 2024 Richard Green, Chiara Bedon, Laura Galuppi, Andrew Crosby https://creativecommons.org/licenses/by/4.0
Panoramic Perfection: Unveiling Technical Insights from “The Henderson” in Hong Kong
The organic design and seamlessly reflective surface of “The Henderson” establish it as a landmark in Hong Kong. With its all-glass façade and a height of 210 m, the skyscraper designed by Zaha Hadid Architects offers spectacular panoramic views. Particularly noteworthy is the “Banquet Hall” on the top floor, distinguished by its fully glazed roof and engineered by Eckersley O’Callaghan. Large-format, coated and curved glass panes with the best possible technical specification in terms of thickness and minimal dimensional tolerances counterbalance architectural aesthetics and structural resilience. Engineered, manufactured and installed by seele, they serve as effective shields against solar radiation and glare, seamlessly complementing the organic architecture. Collaborative efforts focused on maximizing the transparency of the building envelope as interdisciplinary teams navigated challenges in structural engineering, design aesthetics and compliance with strict regulatory standards of the building authorities in Hong Kong. Thanks to targeted investigations, advancements in glass construction technology and engineering innovation, a procedure was developed that ensured optimum bearing of the panoramic glass panes. This project contributes to the safety and durability of high-rise glass structures to withstand extreme conditions and showcases the transformative potential of bold design concepts, rigorous testing, and international collaboration. The result is a visually stunning and structurally outstanding masterpiece.
Copyright (c) 2024 Andreas Komm, Markus Bruckner, Anna-Maria Heinz https://creativecommons.org/licenses/by/4.0
Viscoelastic Fractional Model with a Non-Uniform Time Discretization for Laminated Glass: Experimental Validation
We discuss a novel approach, based on fractional calculus with a non-uniform time discretization, to numerically simulate interlayer viscoelastic behaviour and associated time-dependent deformation of laminated glass. Reference is made to the classic example of a simply supported laminated glass beam under long-duration loads. The fractional model is compared with some results obtained using the widely used finite element software ABAQUS 2021, which for the viscoelastic properties of the polymeric interlayer, utilizes the more traditional approach based on the Wiechert model and approximation via Prony series of the relaxation function and a uniform discretization of time for the numerical solution. The model is also validated through the comparison with experimental test. The novel approach based on fractional calculus presents two main advantages: 1) the definition of the model parameters from experimental data is simplified; and 2) the numerical implementation is easier and computationally more efficient. When a long observation time is considered, the use of a non-uniform time discretization presents the great advantage of not neglecting any part of the relaxation function. Use of traditional uniform time discretization requires the use of large time steps making it impossible to describe all the changes of the relaxation curve within the large time interval. Practical examples will be presented using viscoelastic models for Trosifol® Extra Stiff (PVB) and SentryGlas® interlayers. This methodology also shows potential to advance next generation standards for the design of structural laminated glass.
Copyright (c) 2024 Lorenzo Santi, Stephen Bennison, Michael Haerth https://creativecommons.org/licenses/by/4.0
Experimental Study on the Thermal Performance of Soda-Lime-Silica Glass by Radiant Panel Testing
Assessing the fire performance of structural materials is crucial for ensuring the safety and integrity of buildings and structures. Traditionally, this assessment involves expensive and time-consuming physical fire tests. However, an alternative cost-effective approach is numerical modelling, which requires a deep understanding of heat transfer mechanisms specific to the material of interest. While numerous models exist for opaque materials, modelling glass in fire conditions presents additional complexities due to its transparency and wavelength-dependent heat transfer characteristics. This paper presents an experimental campaign employing an electrical radiant panel as the heat source to investigate the heat transfer phenomena in glass. The radiant panel consists of 21 emitters capable of producing a uniform radiative heat flux on glass specimens of different thicknesses. The experimental results allow us to derive heat transfer ratios specific to the glass material. These ratios are essential for accurate fire simulations, understanding heat transfer through glass, and quantifying the transmitted radiation through the glass, which is important for the combustible materials on the unexposed side of the glass component exposed to fire.
Copyright (c) 2024 Evelien Symoens, Ruben Van Coile, Jan Belis https://creativecommons.org/licenses/by/4.0
The Port of Montreal Tower is a uniquely shaped observation tower situated at the south end of the Alexandra Quay Maritime Terminal pier, offering a breathtaking 360° view of the city and the surrounding area. Its top floor gives access to a “glass cage” measuring 2.5 m wide x 3.6 m high that projects 1.5 m beyond the face of the tower wall. This paper describes the challenges presented in the design and construction of this unique all-glass volume that is anchored through the curtain wall directly to the Tower’s steel structure at a height of 55 m above ground. In order to maximize the transparency of the glass elements, steel framing was eliminated and connection hardware was minimized by means of simplification of load paths while mobilizing the structural contributions of all glazing elements. The laminated heat-treated inner lites of the sidewall insulating glass units cantilever outward through the façade, anchored top and bottom to the tower structure by a combination of sliding and fixed pin connectors. Structural silicone adhesive bonds the roof, floor, and soffit panels to horizontal curtain wall members which, in conjunction with the pin connector anchors, provide lateral stiffness, stability and load resistance to the glass structure. While differential vertical movements are anticipated between the perimeter of the “glass cage” and the curtain wall, such lateral movements are precluded by the incorporation of horizontal bracing to the tower framing. The entire glass envelope was assembled and silicone bonded at a controlled environment workshop before being shipped to site, where a challenging and daring installation was successfully effected in winter conditions.
Copyright (c) 2024 Bethanie Cloutier, Albert Eskenazi https://creativecommons.org/licenses/by/4.0
Re-Glass: Product Development Pathways for Post-Consumer Glass
Our research examines the viability of recycling soda lime glass from post-consumer Insulated Glass Units (IGU), mixing various types of architectural glass cullet and fusing them into flat plates by using electric kilns. Those kilns operate at lower temperatures than standard float glass production, which significantly reduces manufacturing emissions. The research outcomes suggest the potential for near-site operations, reducing transportation logistics, costs, and emissions. Strength and emissivity tests were performed on the recycled glass samples, to assess challenges arising from various production parameters including: glass types, processing methods, annealing temperatures and schedules, cullet sizes and distribution. These explorations offer high-level perspectives for developing post-consumer glass solutions driven by emissions and logistics primarily, and tectonics secondarily, exploring the cost-effective diversion of glass products from landfill to generate solutions staying within the built environment. The research examines performance aspects of recycled glass as emblematic of sustainability in design and underscores the role (and implications) of texture in architectural materiality. Performance and viability are weighted with considerations for the US market (hauling distances, energy grid emissivity across states, market culture, labor rates, incentives, or lack thereof). This exploration proposes innovative avenues for integrating distinctive, sustainable recycled glass as a hallmark into architectural frameworks.
Copyright (c) 2024 Sophie Pennetier, Baizhen (Shirley) Yu https://creativecommons.org/licenses/by/4.0
Photovoltaics in façades are currently enjoying great popularity, also as a way of contributing to renewable energy production. There are various subsidy programmes to promote the installation of photovoltaics. Two "worlds" meet here, the world of electricity and the world of construction. In case photovoltaic modules are CE-labelled, the basis for this is not the European Construction Products Regulation but a low-voltage directive. Taking a closer look at the set-up of these modules, one very often finds unregulated construction products: Thin glass, no PVB as an interlayer but other materials, glued constructions - in some cases also point-glued in the form of backrails. With photovoltaic cells a laminated safety glass turns to simple laminated glass. There are also more and more applications that not only act as cladding, but are also installed as fall protection or "overhead". This paper begins with an overview of the different types of modules and their applications. It discusses building regulations including the necessary structural analysis and testing verifications. Another important aspect is the anchoring to the building. Until now most applications are standard applications with framed panels on roofs or installations on fields. More and more attractive applications from the architectural point of view are built or are under construction. Finally, some projects are presented.
Copyright (c) 2024 Barbara Siebert, Geralt Siebert https://creativecommons.org/licenses/by/4.0
Whole Life-cycle Carbon Assessment of Building Retrofits with Water-Filled Glass (WFG) Secondary Glazing
The existing building stock possesses a proportionally high impact on greenhouse gas emissions due to its low operational energy performance; retrofitting is a prominent strategy in many countries to help solve this, and as such is considered important to achieve a carbon neutral society. Among the energy retrofitting measures (ERMs), those impacting the performance of building envelopes are of primary relevance, especially ones that possess high Window-to-Wall Ratios (WWR) over 50%; these are predominantly found in office buildings built after 1960s. Here, the two dominant ERM strategies are to replace low performing elements, or to add secondary layers to the existing glass. This second strategy in particular is shown to present several benefits, however these are seldom considered and verified within a wider Life-Cycle Analysis (LCA). To this effect, this paper aims to quantify the savings achieved through the ERM of secondary layer addition to existing glazed facades, for a high WWR office building in cooling and heating dominated climate locations (Dubai, London, and New York). This is then evaluated against an LCA for each glazing ERM chosen, to assess how each retrofit affects the embodied carbon produced. Two base scenarios in each city have been simulated in TRNSYS (single and double glass cases), with three standard market options for layers addition (single, double, and water-filled glass). Water-filled Glass is introduced as a potential ERM for the first time, that utilizes a water layer to improve performance. The aim of this paper is to evaluate the holistic efficiency of different ERMs within the transparent building envelope.
Copyright (c) 2024 Giulio Cavana, Brandon Mok , Matyas Gutai, Abolfazl Ganji Kheybari https://creativecommons.org/licenses/by/4.0
Structural Topology Optimization for Abrasive Water-Jet Fabricated Glass
The application of structural topology optimization to glass may enable the design of architectural and lightweight glass structures. There is still a lack of specific topology optimization tools for such a brittle material. This work establishes a topology optimization computational method for the design of glass structures fabricated via abrasive water-jet cutting. This allows to obtain load-bearing glass components which can have a high strength-to-weight ratio while accounting for changes in mechanical properties induced by the fabrication process. Here, we consider a volume minimization problem in which global displacement and global maximum principal stress design criteria are considered. The optimization algorithm is developed based on a density method with a robust filtering method. The Method of Moving Asymptote (MMA) is used as the standard optimizer. The numerical examples are presented in both 2D and 3D design structures. We perform topology optimization with mechanical properties specifically obtained experimentally for water-jet cut glass. We find that customized topology optimization can minimize effectively the volume of the structures and improve structural performance.
Copyright (c) 2024 Kimhong Heng, Maxime Vassaux, Raveth Hin, Chansopheak Seang, Eric Robin, Jean-Christophe Sangleboeuf https://creativecommons.org/licenses/by/4.0
Design of a Numerical Sensor Concept as the Basis of a Hybrid Digital Twin for Monitoring Load-Bearing Glass Façades
Recently, increased efforts have been made to explore the possibility of using glass panes as structural components, such as shear stiffeners. However, there are obstacles to the widespread use of these panes, even though they have proven their load-bearing capacity in structural systems (Haese 2013). The sudden failure of individual glass panes is a major concern because it can affect the overall structural safety. To better understand the causes of this unpredictable behaviour of glass façades, a numerical and physical sensor concept in the form of a hybrid digital twin will be developed. This involves both measurements of real load-bearing systems and simulations using numerical sensors. The two concepts will initially be developed independently, whereby the virtual model is approximated in a continuous process using measurements of the real structure. For this idea of the hybrid digital twin, a numerical sensor model is first presented in this article, which is also used for the evaluation of real sensors and thus serves as a basis for further investigation. The research project on the safety of glass façades in load-bearing structures is an important step towards improving the reliability and durability of such structures. The introduction of a hybrid digital twin will contribute to the development of an improved safety concept and the further establishment of these applications.
Copyright (c) 2024 Nathalie Nießer, Geralt Siebert https://creativecommons.org/licenses/by/4.0
Reducing Deflection of Thin Glass by Prestress
Enclos has identified a novel technique to substantially stiffen glass via prestress. Significant reductions in deflection of thin glass have been demonstrated numerically and on prototype mockups using this technique. The potential integration of this technology with glass such as AGC’s Falcon Glass presents opportunities for performance improvement and material optimization. This study examines prestressed glass specimens which are 0.5mm, 1.1mm, and 2.1mm thick in comparison to glass of the same thicknesses that has not been enhanced by the novel stiffening method. The technology relies on a prestress pattern generated by cold-forming a double-curved surface into a flat pane. Unlike most cold-warping that starts with a flat sheet of glass deformed to a final warped surface, this approach begins with a hot-formed glass shape that is flattened elastically to a planar lite. The process results in a pattern of membrane prestress contained within the glass. As a result of the deformation, the center region of the glass is put into tension, which is balanced by regions of compression within the glass at the perimeter, adjacent to the frame. The membrane tension region that develops increases the glass stiffness for deflections out-of-plane, in a similar manner to the way tensioning a cable generates higher stiffness to resist applied lateral loads acting on it. Numerical models and test results from Enclos and AGC are presented in this study.
Copyright (c) 2024 Austin Bensend, Marco Zaccaria https://creativecommons.org/licenses/by/4.0
Spontaneous Breaking of Thermally Toughened Safety Glass in Facades
Spontaneous glass breakage of thermally toughened glass due to NiS inclusions can be largely prevented by a Heat Soak Test (HST)1. This well-established test has been incorporated into the European standard EN 14179-1:2005. However, according to literature (Yousfi 2010b), there might be a theoretical probability, that a potentially dangerous inclusion could lead to a breakage after a well-conducted HST. Glass processors may neglect to conduct the test for a variety of reasons (sometimes furnaces are not calibrated, are overloaded, a wrong temperature profile is run etc.), even advising not to perform it at all, preferring to replace the glass should failure on a building occur. In this talk, we will show that, due to recent advances in microanalysis techniques, it is now possible to state after a failure on a building whether the heat soak test was correctly conducted according the EN standard or not.
Copyright (c) 2024 Philippe Letocart, Francis Serruys https://creativecommons.org/licenses/by/4.0
For a residential building in the French Alps, Vitroplena designed and installed an all-glass walkway. The structure connects the upper platform of the stairwell and the master bedroom spanning a distance of 5.28 m. The width of the bridge is approximately 1 m. The structural performance of the walkway relies on a 101010.4(TTG,sPVB) floor plate supported by 200 mm high 101010.4(TTG,sPVB) structural glass beams. The accompanying 1010.4(TTG,sPVB) balustrades are laminated to these structural glass beams. A key feature of this design is the adhesive bonding of the floor plate to the balustrades and the structural glass beams using a transparent acrylic adhesive. The bonding process was executed entirely in situ. The end supports of the all-glass walkway take the form of discrete steel shoes with neoprene elements to avoid hard glass-steel contact. These supports are concealed behind a wooden cladding. The design process encompassed finite element modelling, implementing viscoelastic behaviour of the interlayers and hyperelastic behaviour of the transparent acrylic adhesive. The innovations introduced in this project come in several dimensions: only three glass components are used, which are bonded together to form a cohesive structural entity using a transparent acrylic adhesive, which maximises transparency by eliminating conventional steel connectors. This paper elucidates the design principles, the challenges encountered during installation and the intricacies of the in situ bonding. This project serves as a reference of all-glass applications using structural adhesive bonding, and therefore contributes to the advancement of structural glass engineering.
Copyright (c) 2024 Bert Van Lancker, Kenny Martens https://creativecommons.org/licenses/by/4.0
At the core of facade design is the concept of interdisciplinarity, a bridge between concept and materialization apt to relay a built form effectively responding to a wide and diverse spectrum of parameters and aspirations. This paper presents a case study where a facade design approach has been successfully applied to the design and development of a highly complex artwork constituted of structural glass elements. C-010106 by Sarah Oppenheimer—commissioned by the University of Texas’ public art program, Landmarks—is comprised of two structural glass systems acting like periscopes to generate novel views and perspectives from both above and below the footbridge where it is installed.
Copyright (c) 2024 Michele Andaloro, Enrica Oliva, Lucio Blandini https://creativecommons.org/licenses/by/4.0
Mechanical Properties of Glass Plate During Anticlastic Cold Bending
Anticlastic glass surfaces play a significant role in free-form glass facades. For realizing anticlastic surface, cold bending by loading at the corner of the plate is more adaptive and more economic than traditional hot bending method. Previous research on anticlastic cold bending mainly focuses on the description of instability phenomenon and qualitative analysis of parameters. However, the failure mechanisms of glass plates during cold bending and the influence of lamination remains unclear. In this paper, the anticlastic cold bending test was conducted to explore the influence of various factors, including aspect ratio, scale and composition of the plates. Subsequently, an effective finite element model was established and validated by test results, which is used for further explore the cold bending controlling condition for better engineering practice. The failure modes are considered as instability and strength failure. For laminated glass, maximum stresses can be derived from monolithic glass based on equivalent thickness method. The instability is induced by the compression area in the middle surface of glass plate which is significantly influenced by the composition of the laminates. Consequently, thin glass laminates exhibit enhanced stability because a reduced glass to PVB thickness ratio changes the compression area from bi-directional to uni-directional.
Copyright (c) 2024 Xiaohan Hao, Suwen Chen https://creativecommons.org/licenses/by/4.0
In this paper we will discuss a challenging, iconic, heritage, refurbishment project – Channel 4’s headquarters building located in London, England. The building was originally designed by Richard Rogers and Partners in collaboration with Arup, RFR and was executed in 1994 by Eiffel under a sub-contract package with Permasteelisa. We will methodically outline the procedures that were followed to assess and restore this ageing, iconic cable net façade where, in an almost unprecedented way, the face glass is used structurally to support the dead load of the panels below to create a chain of suspended glass panes. After approximately 25 years of service Arup was called back to provide advice to the client following a glass breakage incident. This triggered a detailed condition survey which concluded that a project refurbishment was overdue. Arup then provided further studies to inform strategic options as to how to best refurbish the façade. This advice led to the appointment of Octatube to provide Pre-Construction Services Agreement (PCSA) support to assist the façade appraisal and to carry out design, material testing, calculation and to provide critical construction advice, and then lead to Ocatatube’s appointment to fully refurbish the iconic façade.
Copyright (c) 2024 Peter Lenk, Peter van de Rotten, Ed Forwood https://creativecommons.org/licenses/by/4.0