Challenging Glass Conference 7 was held as webinar on 4 September 2020 at Ghent University and was organised by Prof. Jan Belis (Ghent University), Dr. Freek Bos (TU Eindhoven) and Prof. Christian Louter (TU Dresden).
The conference proceedings have been published by TU Delft Open with ISBN 978-94-6366-296-3.
Cover image credits: Mediated Matter Group, MIT Media Lab
The 7th edition of Challenging Glass is unlike any of the previous events in the 12-year history of the conference. Due to the ongoing corona pandemic, the on-location event has been replaced by an online webinar, featuring a keynote by Chikara Inamura and a small selection of short paper presentations.
We are proud to, nevertheless, be able to present to you these Challenging Glass Conference 7 Proceedings, which are published Open Access in collaboration with TU Delft Open. The proceedings contain more than 50...
This paper describes the design process UNStudio undertook in the redevelopment of the C&A Building on 18 Septemberplein in Eindhoven, the Netherlands. The design brief primarily called for the rebranding of the building while maintaining the building’s façade historic value and aesthetic. Secondarily, the design is meant to activate the urban context where the building is located without competing with the neighboring landmarks. UNStudio saw an opportunity to rethink the transparent layer – the glass window – of the building as a tool to enhance its identity minimizing the aesthetic...
This paper explores two alternative mould fabrication technologies that allow for the casting of (solid) glass components with a great degree of freedom in shape and size and/or of a customized design, in a cost-efficient way. In specific, the paper discusses the research, design and experimental work conducted at TU Delft on 3D-printed sand moulds and adjustable, high-precision steel moulds. 3D-printed sand moulds can provide a high-accuracy, cost-effective solution for solid glass components of complex geometry and/or of customized design. Although this mould technique is already used...
In today’s architecture the bending of glass plays an important role in achieving free forms in modern façades. In addition to the usual procedure of hot bending glass sheets into the desired shape, the option of cold bending is being used more and more frequently. In this process a glass pane is bent into the desired shape and fastened to a substructure without prior heating and at low cost. This inherent bending state comes along with different beneficial but also with some unfavourable perks that have to be considered in the engineering process. The resulting influences on the...
Glass with a thickness of less than 2.0 mm can be defined as a thin glass or with a thickness of less than 0.5 mm even as ultra-light. Thin glass requires for curved surfaces in order to gain structural stiffness in static use. The geometry is based on the known theory of developable surfaces. Such Façades may therefore be created from cold bent or curved laminated thin glass layers. In the past semester a seminar with architectural students were held and three projects of this seminar are worth to be presented to the public for demonstration of possibilities for use of thin glass. The...
Within several research projects and with the aim to optimize structural performance, energy efficiency and ecological characteristics of structural building components the Department of Structural Design and Timber Engineering (ITI) at the Vienna University of Technology (TU Wien) developed several wood-based composite systems combining timber and wood concrete as well as structural glass components. Certain advantages in the application of these individual composite systems could be shown within the described former research activities. Due to a suitable combination of the named...
The problem of sustainability represents one of the most important issues that the world has to face nowadays, not only in terms of energy consumption and of the consequent CO2 emissions, but also in terms of material waste streams that end in landfill. 38 million tons of glass waste are produced every year in the European Union and new targets have been set for 2020 towards a more sustainable management of such wastes. Nowadays, only the container glass industry has reached a considerable recycling rate, while for all the other sectors we are still witnessing downgrading...
Shells made of structural glass are beautiful objects from both the aesthetics and the engineering point of view. However, they pose two significant challenges. The first one is to assure adequate safety and redundancy concerning possible global collapse. Being single-layered, in a shell made of structural glass, the brittle cracking of a single pane can lead to a sudden propagation of failure, up to instability. The second one is to guarantee cheap replacing possibilities for potentially collapsed components. This research explores a novel concept to address both...
Structural solutions involving the mechanical interaction of timber and glass load-bearing members showed a progressive increase in the last decade. Among others, a multipurpose hybrid facade element composed of Cross-Laminated Timber (CLT) members and glass panels interacting by frictional contact mechanisms only was proposed ion the framework of the VETROLIGNUM project. While demonstrating enhanced load-bearing and deformation capacity performances under seismic loads, facade elements are known to represent a building component with multiple...
This paper investigates the stiffness and the durability of a composite panel that consists of thin glass as outer layers and a 3D printed core element from recycled PET. Thin alumino-silicate glass, mostly used for displays in computers, tablets and smartphones, is known for its flexibility, durability and high bending strength. However, for building applications, the high flexibility of thin glass may cause serviceability issues. Therefore, to stiffen thin glass, a composite concept of thin glass with a 3D printed core is developed. The core element of this panel consists of 3D...
This paper presents a novel concept for improving the long-term load-bearing performance of reinforced glass beams (hybrid beams). The concept of reinforcing glass beams using steel or other (ductile) materials have been investigated over the last couple of decades utilising the fracture pattern of annealed glass to ensure a ductile behaviour. However, it is well known that the long-term strength of annealed glass is rather low due to so-called static fatigue leading to a relatively poor
performance for most hybrid-beams. As an example will a hybrid beam based on annealed glass...
Double Glazed Units (DGUs) consist of two glass panes held together by structural edge seals. Calculation methods for DGUs consider that actions applied on one pane develop effects in all the panes, due to the coupling from the entrapped gas. Various methods have been proposed in standards to evaluate this load sharing, which depends upon the stiffness of the glass panes, the thicknesses of spacer and the size of the DGU. A comprehensive analytical formulation, the Betti’s Analytical Method (BAM), has been recently proposed to calculate the load sharing in DGUs of any shape,...
A simulation tool for simple flat and cylindrical insulated glass units (IGUs) has been developed using VBA code included on Excel and RF-COM, the programmable COM Interface for the RFEM of Dlubal. The software allows the non-linear computational analysis of rectangular flat panels and cylindrical IGUs considering the monolithic equivalent thickness of the inner and outer glass panel. The sealant silicone elastic properties can be defined by the users, including, if necessary, the rotational stiffness. Climatic load and superficial uniform loads (typically wind loads) can be defined.
...
Due to several advantages, insulated glass units (IGUs) are largely used in buildings to realize curtain walls, vertical partitions but also roofs or pedestrian systems. The typical IGU consists of two glass layers, either monolithic and/or laminated sections, that can mechanically interact via an hermetically-sealed air (or gas) cavity between them. As known, load sharing phenomena have a crucial effect on the actual mechanical response of a given IGU. Accordingly, simplified analytical methods are available in the literature to account for these load sharing effects. The existing...
Insulated Glass Units (IGUs) typically consist of two glass layers, either monolithic and/or laminated sections, that mechanically interact via an hermetically-sealed air (or gas) cavity, and a series of linear spacer connections along their edges. In this paper, based on the experimental tests for small-scale IGU joints under pure shear and IGU prototypes in bending discussed in “Part I”, a special care is spent for the Finite Element (FE) numerical characterization and analysis of these composite systems, with a focus on the actual mechanical properties and load-bearing mechanism for...
Aside from external cladding pressure loads that are always considered in IGU design, a variety of unique factors must also be addressed when analyzing the structural performance of a slumped IGU with a large air cavity. These factors include the volume of air within the cavity, the stiffness and strength of the outer and inner lites of glass, elevation changes between the glass fabrication facility and the building site, temperature changes over time, fluctuations in barometric pressure, and increased stress on the secondary structural perimeter seal. Appropriate deflection limits for...
Use of glass as a load bearing structural elements has increased significantly in last years. The glass is brittle material, which behaves elastically until brittle failure which occurs suddenly without any warning. Therefore, special emphasis shell be devoted to the connections with load bearing role. Their inappropriate design can lead to local peaks of stress or eccentricity of the connections and the generation of additional moments, resulting in a reduction of the load-bearing capacity. Currently, mechanical (clamped, friction-grip and bolted connections) or adhesive joints are...
Embedded laminated connection (ELC) is a novel type of connection in structural glass and its application increases the transparency and surface flatness of structural glass elements. In this study, laboratory tests have been conducted to investigate the mechanical behavior of embedded laminated connections. Two groups of ELC, i.e. ELC laminated with triple annealed glass layers (TA-ELC), ELC laminated with double outmost tempered glass layers and one mid annealed glass layer (DT-ELC). The data of the pull-out force and displacement of the ELC under the pull-out load was collected and...
In recent years, architects, as well as customers, have been increasingly interested in glass structures. Glass is used except facades also for canopies above building entrances, bannisters, staircases or load-bearing structural elements such as beams or columns. Glass is a brittle material with elastic behaviour until brittle failure so particular attention should be paid to details and connections of glass with glass or glass with other material. This article is focused on double-lap shear glass-metal joint using a two-component acrylic adhesive. In addition to glass, two different...
The use of Structural silicone glazing (SSG) systems in large commercial glazed facades is well established in current practice, mainly due to the architectural aspiration of having a continuous smooth glass surface across the building elevation. Enhanced thermal and security (blast) performance are typically listed as an advantage for this particular type of systems. SSG façade systems are structurally complex due to the fact that multiple load-paths can be identified within the system. It is accepted as good practice to detail façade...
The embedded laminated glass connection belongs to the group of the most widely used ways of the glass components connecting. As it becomes common to use glass as a material for load-bearing elements, the connection must be able to bear stresses arising during the lifetime period. To find out the load capacity of the connection under different loads, experiments have to be performed. Within the ongoing research at the Faculty of Civil Engineering of Czech Technical University in Prague, two series of experiments of the embedded laminated glass connection have been performed. There were...
Connecting glass with heat bonds is a way to create all-transparent glass structures. Two methods have been researched in theory and practice, glass welding, through local heating, and glass fusion through global heating. Both methods have been applied to produce 10 mm thick T-sections of soda lime glass while preventing thermal shock failure and minimizing residual stress. These specimen, and specimen with an adhesive joint, have been tested destructively. It is concluded that it is possible to connect 10 mm thick soda lime glass by welding, if the...
This paper deals with the application of the semi-probabilistic design concept (level I, DIN EN 1990) to structural silicone adhesives in order to calibrate partial material safety factors for a stretch-based limit state equation. Based on the current legal situation for the application of structural sealants in façades, a new Eurocode-compliant design concept is introduced and compared to existing design codes (ETAG 002). This is followed by some background information on semi-probabilistic reliability modeling and the general framework of the Eurocode for the derivation of partial...
The method of fiber optic strain measurement based on Rayleigh signal analysis enables the detection of the deformation behaviour of glass laminates for the purpose of modelling its load-bearing characteristics. With distributed fiber optic sensors, which consist of a diameter of 0.16 mm, it is possible to determine strain patterns on both glass surfaces and its interlayers. The sensors used in tensile and bending tests on monolithic as well as laminated glass supplement the deformation measurements taken with strain gauges and inductive displacement sensors. The study describes the...
Interlayer modulus properties are important for the calculation of the load resistance of laminated glass configurations. The determination of interlayer properties can be made on the interlayer material directly, or indirectly through measurements on laminated glass test specimens. One challenge relates to the four-decade range of modulus values that interlayer materials go through with variations of temperatures and duration that are relevant to building elements. Furthermore, in determination of properties directly on the interlayer, e.g. by dynamic mechanical analysis, methodological...
The built environment is under scrutiny to address environmental design challenges by considering a whole-life holistic approach that seeks reductions in operational emissions whilst simultaneously pursuing reductions in embodied emissions. Reduced embodied emissions can be found through the responsible sourcing of resources and re-use of materials in their highest obtainable value. Laminated glass is used widely within the building industry for improving security and for reducing the risk of human injury from glass fracture. At present, few options exist for the re-use and high-value...
Current architecture uses glass even for load bearing structural elements. Typical example is perpendicularly loaded laminated glass panel as a part of balustrade, staircase, or canopy. Laminated glass is a composition of two or more glass plies bonded by polymeric interlayer which enables the shear transfer between the individual plies in a laminated panel. The shear transfer depends on the shear stiffness of a certain interlayer as a time and temperature dependent parameter. Shear stiffness in time and temperature domain can be numerically described by a discrete Maxwell model whose...
Innovative glazing, which combines polycarbonate and thin glass to composite panels, ensures a slighter alternative to glass laminates with a high resistance against manual attack. Due to experimental studies, these thin glass-polycarbonate composite panels are classified as laminated safety glass and security glazing. The study describes analytical models to analyse their structural behaviour for static short time loads. In accordance to the geometrical boundary conditions of the four-point bending test, the composite panel can be described by the beam theory. A multi-layered system is...
An adequate understanding of the response of laminated glass structures to impact loading becomes essential to rationalise their design, which has been proven by several studies that appeared in the last years. Our study focuses on the behaviour of three-layer laminated glass plates subjected to the low-velocity impact of a steel impactor. Using combined experimental and computational analysis, we study the influence of the laminated glass composition on the response of laminated glass, crack initiation and the final fracture pattern. A polyvinyl butyral or ethylene-vinyl acetate...
This paper presents the experimental results of a three-point bending test conducted on laminated glass at elevated temperature in an environmental chamber. The focus of the present research was on bending stiffness degradation of the laminated glass in correspondence to elevated temperature. The tested specimens were made of two fully tempered glass plates bonded with EVA and PVB interlayers. For each type of laminated glass and set temperature, we prepared and tested 5 specimens. Each of the specimen was preconditioned to a set temperature before the experiment conducted in an...
Laminated safety glass (LSG) is increasingly used as structural element in buildings. Of central importance for safety are the adhesion and the residual load-bearing capacity in the post fractured state. In literature a large number of tests to assess adhesion is mentioned. These include, e.g. peel tests, through-cracked-tensile/-bending tests, VW-pull tests and compressive shear tests. However, especially in industry, the Pummel test is widespread for determining the quality of adhesion in LSG with polyvinyl butyral based interlayers. This test method proves to be simple and quick to...
In laminated glass under impact, most of the energy dissipation occurs in the coupled delamination and deformation of the polymer interlayer. The strong dependency of these mechanisms on interlayer nature, on loading rate and on temperature is known: however, the effect of the interfacial adhesion is unexplored. In this work, a surface modification technique is proposed, along with a mechanical characterization of the debonding with the Through Crack Tensile Test. We show that changing adhesion mostly affects dissipation close to the delamination front, while dissipation in the volume of...
The load-bearing capacity of glass as a structural material as well as sustainability and resistance of a built-in glass against appearing loads and forces is assuming an ever-greater importance. Next to analytical and numerical calculations of maximum load-bearing capacity and the ultimate limit state, there is no generally accepted standardized non-destructive inspection method available, with which it is possible to estimate the prevalent load situation and predominant stress conditions, particularly in relation to mechanical or adhered connections. Within the research project...
Glass has become an indispensable construction material. However, in extreme events such as fire, the behaviour of glass elements is still relatively unknown. The susceptibility of glass to thermal shock and its changeable material properties when subjected to high temperatures make predicting the behaviour of glass elements during fire complex. Practical applications of fire-resistant glazing, however, already exist as infill panels and frameless glass walls/doors, and are commonly used. They are highly effective to maintain compartmentation, providing temporary protection of the...
In this work, a combined Voronoi and finite-discrete element method (FDEM) approach for reconstructing the post-fracture model of laminated glass (LG) was proposed. The fracture morphology was determined via introducing Voronoi tessellation with statistical distribution parameters such as the fragment face numbers, volume and sphericity. The residual interaction between glass fragments was described with cohesive zone model. One fractured LG block under uniaxial tension, which was taken from a triple layered LG beam with ionoplast interlayers, was...
This paper dealt with the theoretical and experimental dynamic behaviour of laminated glass. The developments are based on the contrasted plate model (Boutin and Viverge 2016) that accounts for the high contrast of mechanical properties between the glass layers and the soft viscoelastic interlayer through the additional kinematic variable describing the sliding between the glass layers. This yields an analytic tri-Laplacian representation that encompasses (i) the shear related to the sliding within the PVB, (ii) the local bending of each glass layer, and (iii) global bending of the whole...
The Fraunhofer EMI shock-tube facility “Blast-STAR” is used to simulate blast loadings from high explosive detonations similar to realistic conditions. Mainly tests on explosion-resistant safety glazing and façades are carried out. Due to the extreme conditions during the test, it is not trivial to accurately analyze the specimen reaction and in particular to determine the start of breakage of the glass pane. Usually high-speed footage is used for this purpose. Since the size of tested elements is increasing, the determination of place and time of...
Since time began there has been a strong fascination in foreseeing the behavior of buildings and constructions. Now In order to predict this behavior, we use experimental, and increasingly more time- and cost-effective, computational simulations. Finite Element Analysis (FEA) is a method that has become increasingly prevalent and has become firmly established in aviation and vehicle construction for decades. In recent years, there has been a marked growth in the use of numerical simulations for the verification of adhesive bonds, particularly in façade development where polymeric...
The failure of glass has been studied extensively by many researchers. However, the focus has previously been on the static to quasi-static, rate-independent behaviour. It is commonly accepted that the strength of glass is sensitive to the applied loading time, however, the amount of research in the field of loading rate dependency seems very limited. Consequently, the effect of loading rates on the strength is sparingly described in the available literature despite its relevance when designing for impact and blast loads. The present paper presents an ongoing research project considering...
It is not obvious to talk about glass recycling when we realize that a mature recycling procedure for glass bottles is already working well. However, apart from glass bottles, unfortunately, that a large amount of glass will disappear into landfills. This large quantity of unrecycled glass indicates that there is a large potential in upgrading the glass recycling process. In the field of architecture, we see a fast-growing interest in using glass, also for structures. The glass bricks of Crystal Houses in Amsterdam are a good illustration. Aiming at...
b Si-X, the Netherlands
The C&A building in Eindhoven will be modernised and therefore UNStudio designed several glass structures for the building. One of these glass structures are four glass boxes of 5,5 meters wide and 7 meters high, which are floating in front of the existing façade. In addition, each glass box contains a work of light art designed by Arnout Meijer. LED strips illuminate the box from the inside, while the reflective film on the glass creates an unusual and striking effect. To optimize this effect no metal connections were allowed in the...
The building of the National Museum in Prague is a part of the historical heritage of the Czech Republic. Very huge reconstruction and maintenance of whole building was ongoing during the last decade. Special emphasis was devoted to every detail of the interior as well as the facade elements to keep the historical value of the building adding modern architectural elements like transport glass flooring and balustrades. This paper deals with the project of the glass flooring in total area about 200m2 placed directly in the main tower of the building as a representative place with nice view...
Compared to flat sheets of float glass, cast glass components have a thicker geometry and thus a high buckling resistance. This buckling resistance in combination with the high compressive strength of glass make cast glass components suitable for the construction of fully transparent shell structures that are mainly subjected to compressive stresses. Shell structures often have the shape of surfaces with varying Gaussian curvature. When constructing such a shell structure out of cast glass components, components of varying geometries are needed. An adjustable mould was developed that can...
The former Diamond-exchange building in Amsterdam, now called Capital C, is restored to its former glory and currently undergoing a major renovation. This listed building has been returned to its original design and topped with a spatial gridshell roof structure of glass and steel, designed by renowned architect office ZJA Zwarts & Jansma Architects. This paper focuses on the geometric optimization of the free-form gridshell towards planar quad glass units.
The final shape of the gridshell is determined by a parametric computer model. With a by ZJA in-house...
A bespoke structural glass storefront is designed for the P.C. Hooftstraat 138. Developer Warenar Real Estate assembled a design team with UNStudio, Arup and Octatube. The façade features twisted geometries with precisely detailed glass connections and custom non-orthogonal steel and glass doors. At ground floor level the facade starts flush with adjacent buildings but rising up it also leans and cantilevers outwards to become more visible from a distance. For optimal quality and minimalistic detailing, a scheme was designed in which most elements...
Renzo Piano Building Workshop designed a 290,000 sf museum celebrating the artistry and technology of film, becoming the world’s first museum and event space devoted to the Motion Picture. The 388 Mio USD project consist of a six story tall renovated existing building and a dome-shaped iconic new building housing a 1,000-seat theater. Both buildings are linked by several – partially suspended – bridges. The 150 ft diameter dome is a steel grid shell with cable bracing and flat, shingled glass panels on a secondary layer. The single-layered curved structural steel tubes have a diameter of...
Erin Mills Town Centre is a shopping mall in Mississauga, Canada owned by Cushman & Wakefield in Toronto. The revitalization project was designed by MMC International Architects Ltd. and features a 27.4m diameter glass and steel globe at its Centre Court. The structural glass for this globe structure is created with laminated double curved glass panels patch supported by a steel structure. Some challenges arose during construction due to the frit on the glass panel and the thermal stress created between the inner and outer lites of the laminated assembly. Testing was used to...
The Green Village at the TU Delft is a living lab for sustainable innovations. The Co Creation Centre will be their new meeting centre. This centre is getting a climate tower and to get the isolation standards, triple glass was necessary. Unfortunately, the original design for the centre was too expensive. The triple glass was one of the big cost items.
Then the team got the ingenious idea to use the façade as the bearing and stabilising structure. This idea made the project feasible in costs.
The aim was to design a façade with as few as possible modifications compared...
Since 2010, Octatube has adopted glass fins as structural components in at least 20 different projects, both in facades and roofs (the van Gogh Museum, the Tottenham Experience, Canal House Amsterdam are some relevant examples). Glass is widely known as a fragile material and it usually breaks in a brittle fashion, whereas a metal like steel typically fails plastically. The post-breakage behavior of glass beams is not easy to predict, therefore Octatube performed a range of tests on different glass fins varying the test setup. All tests were performed in house, at Octatube’s factory/test...
Square One Shopping Centre is owned by Oxford Properties in Toronto, Canada, and was designed by MMC International Architects Ltd. The shopping centre went through a recent expansion and features a large glass and steel rotunda for its feature entrance into the new expansion. The feature glass wall is oval in plan and is 18m tall utilizing a custom splicing detail to minimize the use of steel at the connections. The fin wall was analysed and tested to ensure the connection detail behaved as predicted. This paper will visit the design of the fin wall and review the findings of the...
The TU Delft glass group designed, developed and build three glass sandwich panels for the Glasstec 2018 in collaboration with ARUP. These were composed of heat strengthened laminated float glass with Schott glass tubes as the core. Initial small scale tests were used to determine the parameters for the digital design by ARUP. Based on these results form-finding was used to determine the optimum configuration of the glass tubes in the panel. This was verified by further scale model experiments which led to more refinements in the form finding algorithm. The small scale tests were extend...
Thin glass offers a promising prospect for lightweight façades with reduced use of raw materials, also opening up entirely new perspectives for architectural expression with its excellent optical quality as well as its high flexibility. The realisation of projects featuring thin glass as a structural element is so far limited due to several challenges led by structural issues mainly induced by the product's low stiffness. This paper attempts to bypass this issue by exploring the possibilities of the structural application of thin glass as a membrane element using examples of all-glass...
The five-star luxury Hotel Ritz in Madrid is currently under refurbishment. The works include the construction of a new large skylight above the main hall inspired on the original design. This paper focus on the design and construction of this skylight which consist of 2 different parts, the Hall Bajo with a vault shape, and the Hall Alto which is a trapezoidal dome crowned by a pyramid roof. The structure consists in slender steel welded T profiles and small rectangular plates which connects the main beams. The connections between the structural members are welded in order to obtain a...
'Big data' and the use of 'Artificial Intelligence' (AI) is currently advancing due to the increasing and even cheaper data collection and processing capabilities. Social and economical change is predicted by numerous company leaders, politicians and researchers. Machine and Deep Learning (ML/DL) are sub-types of AI, which are gaining high interest within the community of data scientists and engineers worldwide. Obviously, this global trend does not stop at structural glass engineering, so that, the first part of the present paper is concerned with introducing the basic theoretical frame...
The paper introduces a novel concept for structural glass shells that is based on the mechanical coupling of double curved heat-bent glass panels and a wire frame mesh, which constitutes a grid of unbonded edge-reinforcement. Additionally, this grid has the purpose of providing redundancy. The panels have load-bearing function, they are clamped at the vertices and dry-assembled. The main novelty lies in the use of polygonal curved panels with a nodal force transfer mechanism. This concept has been validated on an illustrative design case of a 6 m-diameter suspended glass sphere, in which...
The case study presented is a 195 meters tall office tower with a raised podium made of full height glass panels, up to 15 meters high. The panels are only restrained by prestressed high-strength stainless-steel rods, lying entirely in the glass panel build-up, composed by four 12 mm thick plies, laminated with 1.52 mm thick sheets of ionoplast interlayer, with an overall thickness of approx. 52 mm. Due to the facade geometry and the high wind expected, movement joints between rods are introduced, allowing for differential movements to avoid peak stresses in the glass panels. Also,...
The Messeturm (“Trade Fair Tower”) in Frankfurt/Main is currently adjusted to the requirements of a modern office building. The lobby area has been enlarged by a highly transparent façade consisting of oversized insulating glass (IG) units. The IG units are curved and have a size of up to 17 m x 2.8 m. To obtain a perfectly curved façade, the IG units were fabricated with laminated cold-bended glass panes. Horizontally the IG units are supported by tapered stainless steel fins. Inclined steel beams connect the top of the façade fins with the tower structure creating a rounded roof. The...
The new World Trade Center complex in New York City rose up into the heights during the last decade. Nine new buildings including 1776 ft tall One WTC and Calatrava’s sculptural Oculus Station cover the 60,000 m 2 area in the world’s most outstanding construction site. One spot is still under construction and will host “The Ronald O. Perelman Performing Arts Center” – a new kind of multidisciplinary venue with an astonishing smooth facade made from exceptional stone-glass. The cube-shaped building is 49 m x 49 m wide and 42 m tall. A steel roof cantilevers from the inner core and holds...
Eight 45-year-old naturally aged windows collected from two buildings in two different locations revealed surface characteristic bending strengths in the range of 38-54 MPa. An artificial ageing method by sandfall was developed to reproduce the weakest failure stresses among the naturally aged samples. When this method was applied to chemically strengthened glass, the results varied depending on the glass composition and the strengthening cycle. To achieve the characteristic bending strength of 150 MPa specified by EN 12337, after the artificial ageing, soda-lime silicate glass needed...
The strength of thermally toughened glass is regulated in EN 12150-1 for fully tempered glass (FTG) and EN 1863-1 for heat-strengthened glass (HSG). The manufacturer has to prove the strength by four-point bending tests based on EN 1288-
3. A measurement of the residual stresses of thermally toughened glass is not demanded. Consequently, the determination of the strength is containing the amount of residual stresses. As residual stress is depending on the manufacturing process, the amount and distribution can change within one glass pane and between different glass panes. A research...
This paper presents the development of a simple method to determine the full residual stress depth profile in architectural (i.e. construction sector) glass. The proposed model requires only the knowledge of the surface residual stress of glass, which can be known from the glass manufacturer or can be measured using a Scattered-Light-Polariscope (SCALP), as input. The requirement of through-thickness force equilibrium and the knowledge of parabolic shape of the residual stress depth profile are used to...
Glass is a brittle material and any damage or modification of its surface may have a profound impact on the strength. To modify the glass surface, the precision of the instrument is determining for achieving the most reliable results. Nowadays, laser technology as a non-contact tool is employed as a glass cutting, drilling and holing tool in many applications such as sensors and optical communications. Along with high speed, flexibility, and scalability, lasers with short pulse duration can break the interatomic bonds before perturbing the lattice. Among lasers,...
This paper presents an experimental study into the global behavior of glass columns with square hollow cross-section under axial compression. In the research, totally 6 specimens were tested. All specimens were of the same geometry (length 750 mm, width 150 mm and 10 mm) but had different composition. Half of them were made of monolithic glass, with the other half made of laminated glass. The adopted interlayer material is PVB which is widely used in practice. During the test, vertical displacement, lateral deflection and normal stresses at mid-span were measured. For all specimens,...
Designers use exposed glass edges to reach maximum transparency, for example within glass steps, glass beams or glass columns. These applications require mechanical finishing to achieve high optical quality and to compensate for the edge notch that results from the manufacturing process of safety glass. Regrinding of annealed glass is allowed without restrictions. In the case of glass with load bearing functions, tempered glass, heat-strengthened glass or fully tempered glass, is required. However, a risk of premature failure occurs when regrinding tempered glass because of a reduction...
The paper presents basis and experimental results of a non-destructive method aimed at determination of the presence of large surface cracks in glass samples by measurements with NAW® technology (Nonlinear Acoustic Wave). The method is based on a transmitted ultrasonic wave in the material from which the non-linear content of the signal can be analysed. A sample containing defects presents nonlinearities in the form of distortions, such as, higher order harmonics that are detected. Nonlinearities in the signal are primarily formed at crack-tips and...
Glass edges result from cutting glass sheets and a further optional finishing. The mechanical interference into the brittle material glass causes flaws and cracks at the edge surface. Those defects have an influence on the strength of the whole glazing. Within the scope of a research project at the Institute of Building Construction from the Technische Universität Dresden, the grinding and polishing process is examined in terms of characteristic visible effects on the glass edge and the edge strength. Thereby a special focus of the research project is the impact of various polishing cup...
In this paper, artificial intelligence (AI) will be applied for the first time in the context of glass processing. The goal is to use an algorithm based on artificial intelligence to detect the fractured edge of a cut glass in order to generate a so-called mask image by AI. In the context of AI, this is a classical problem of semantic segmentation, in which objects (here the cut-edge of the cut glass) are automatically surrounded by the power of AI or detected and drawn. An original image of a cut glass edge is implemented into a deep neural net and processed in such a way that a mask...
Currently, tons of high quality commercial glass are down-cycled or landfilled due to contaminants that prevent close-loop recycling. Yet, this glass is potentially a valuable resource for casting robust and aesthetically unique building components. Exploring the potential of this idea, different types of non-recyclable silicate glasses are kiln-cast into 30*30*240mm beams, at relatively low temperatures (820 oC - 1120 oC). The defects occurring in the glass specimens due to cullet contamination and the high viscosity of the glass melt, are documented and correlated to the casting...
The strength of glass plays an important role in the dimensioning of glass components in the building industry. Here, not only parameters such as support conditions, loading rate, relative humidity etc. play an important role, but the damage by means of scratches also determines the fracture strength of glass. A heat treatment after damaging may have an influence on the resulting glass strength. The correlation between heat treatment temperature, and in particular elevated temperatures up to the glass transition temperature, and fracture stress has been studied by different researchers...
In the past glass design in Switzerland was based on foreign standards and regulations. Questions raised whether the application of these standards is suitable, as they do not comply with the Swiss Standard SIA 260 – Basis of design. The most used standards are the German technical regulations for the use of glazing with linear supports (TRLV) and the DIN 18008. The Swiss society of engineers and architects (SIA) initiated a structural glass standard committee with the task to develop a Swiss glass design standard. The new Swiss glass design standard is based on the same concept as the...
This study proposes a review of different design approaches allowing to dimension a laminated insert connection. It focuses on façade assemblies, where the critical load is due to wind, and where the stiffness relies on a highly viscoelastic material SentryGlas®. The high variability of material stiffness is considered using three different approaches. The first approach determines critical wind speeds and temperature values using a site-specific probabilistic analysis. The second approach uses the First Order Reliability Method to perform a probabilistic design. The final approach...
Glass is a commonly used material in modern architecture not only for building enclosures but also for glazed barriers preventing building occupants from falling out of balconies or different levels inside buildings. The paper reports some results of an on-going research project involving testing of glass balustrades and infill panels mounted with different fixing methods, such as linear clamps, local clamp fixings, and point fixings through holes in glass. A reduced numerical model for prediction of strength of glass under soft body impact is also presented. In the experimental study...
Structural glass has become a popular material in marine applications. It has been used to enhance the transparency not only in luxury yachts but also in passenger vessels like cruise-ships. Yacht designers being inspired by all-glass facades and structural glass pavilions are trying to adopt these achievements and promote the glass design and engineering technology in the shipbuilding industry. However, designing glass elements in a marine environment involves more challenges comparing to civil applications. Glass engineers should not only consider...
Due to the continuing uncertainty regarding the corona pandemic and the ongoing travel restrictions it is decided to hold Challenging Glass 7 as a short free of charge webinar. The webinar consist of a keynote presentation by Chikara Inamura and selected author pitches.
