Experimental and FE Study on Impact Strength of Toughened Glass–Retrospective Approach

Due to the high cost of experiments commonly performed to verify the resistance of glass elements to impact loads, numerical models are used as an alternative to physical testing. In these, accurate material parameters are crucial for a realistic prediction of the behaviour of glass panels subjected to impact loads. This applies in particular to the glass’s strength, which is strictly dependent on the strain rate. The article reports the results of an extensive experimental campaign, in which 185 simply supported toughened glass samples were subjected to hard-body impacts. The study covers a wide range of glass thicknesses (from 5 to 15 mm), and it aims to determine a critical drop height causing fracture of the glass. Moreover, a 3D numerical model of the experimental set-up was developed to reproduce the experiments numerically and retrospectively to determine the peak stress in glass that developed during the impact. Based on the results of numerical simulations, a load duration factor of 1.40 for toughened glass for impact loads is proposed. In addition, the paper includes a case study to demonstrate the use of the modelling methodology and results of the work on a practical example of an internal glass partition wall.

Simple Laminated Glass Panels with Embedded Point Connection under Short-Term Load

Glass is a very attractive material for contemporary architecture. The trend is to achieve a maximum transparency of structures; therefore it becomes common to use glass as a material for load-bearing structural elements. Glass facades, roofs, beams or columns are widely used in buildings. The problematic part of a glass structure design is the connection between the glass pieces or between the glass elements and substructures from another material (e.g. steel, concrete etc.). The connection must be capable of bearing the stresses performing during the lifetime period and it should be as unobtrusive as possible at the same time. The ongoing research at the Faculty of Civil Engineering of the Czech Technical University in Prague is focused on an embedded laminated point connection for glass structures. Within this research, the real-scale glass panels were tested. The samples consisted of two glass plies bonded with the EVA foil. For the undrilled ply, the float glass was used in all cases. The thermally toughened or the heat strengthened glass was used for the pre-drilled ply. There was one embedded steel countersunk bolt with HDPE liners placed in each corner of the sample. During the experiment, the samples were horizontally placed using the embedded bolts. The load-bearing capacity of the six tested specimens was determined. The load was applied in several loading and unloading cycles until the collapse of the first embedded connection. If the glass panel failed before the connection, the sample was completely unloaded and then the load was gradually increasing until the collapse of the connection. Vertical deflection and the stresses at two different points were measured during the loading cycles. The humidity and the temperature were also monitored. The experiment showed the way of collapse and a short-term load-bearing capacity of a laminated glass panel with four embedded point connections.

An Experimental Study on Cold-Bending Stress and Its Reverse-Coupling Effect with the Uniform Load on Cold-Bent SGP Laminated Glass

SentryGlas® Plus (SGP) laminated glass is a novel type of safety glass with high strength and stiffness. On the other hand, cold bending is a novel technique to build curved glass curtain walls, and is advantageous in terms of its greater energy efficiency and cost-effectiveness as well as its simple construction processes. The cold bending of SGP laminated glass could result in broad applications for the material and provide huge economic benefits in the field of glass curtain wall construction. To study cold-bending stress and its reverse-coupling effect with the uniform load in SGP laminated glass panels, single-corner cold-bending tests, uniform load tests, and ultimate capacity tests were conducted on eight pieces of such panels with different cold-bending curvatures and interlayer thicknesses. The results revealed that cold-bending stress in the glass panels under single-corner cold bending demonstrated a saddle-shaped distribution, with the maximum and second-largest cold-bending stresses located near the corner of the short side and the long side adjacent to the cold-bending corner, respectively. The cold-bending stress and coupling stress increased nonlinearly as the cold-bending curvature rose and the interlayer thickness became greater. Moreover, cold-bending curvature was a factor that affected the cold-bending stress and coupling stress more significantly than the interlayer thickness. The ultimate capacity and ultimate deflection of the glass panels decreased as the cold-bending curvature and interlayer thickness grew.

XRF Imaging (MA-XRF) as a Valuable Method in the Analysis of Nonhomogeneous Structures of Grisaille Paint Layers

Stained glass paint layers made with vitreous paints can be a challenging subject for analyses. Their heterogenic structure requires proper experimental methodology in order to obtain valuable data. The main goal of this paper is to present the advantages of macro-XRF scanning (MA-XRF) in the non-destructive investigation of historical grisaille paint layers on the basis of research conducted on seven stained glass panels from the Dominican Monastery in Kraków, the Diocesan Museum in Kielce and the National Museum in Poznań (Poland). The obtained results showed the capabilities of MA-XRF scanning in technology recognition, the legibility of damaged fragments of painted depictions, as well as with distinguishing the elemental composition between vitreous paints in different colours. Additionally, SEM-EDS measurements are presented so as to acquire quantitative results and additional information concerning light elements.

Simulation Study on the Influence of Fire Partition on Curtain Wall Temperature in Super High-Rise Buildings in China

The poor fire resistance characteristic of super high-rise curtain wall makes the curtain wall design one of the main approaches to improve its capacity for prevention and control over fire and smoke spread. The propagation of smoke leads to the increase in the temperature of the curtain wall on the upper and lower floors of the fire floor and consequently leads to glass fracture and other serious consequences. Current codes have control over fire resistance performance and size of fire partition materials but do not include requirements on the position of curtain walls on floors. By changing the position of fire partition in curtain walls, the paper carries out three comparative simulation experiments on two forms of fire partition: spandrel and fire prevention cornice. Besides, PyroSim is used to calculate the comparative simulation of fire and smoke spread and obtain the data on temperature variation nephogram and monitoring points in the center line of glass curtain walls during different fire scenarios, so as to discuss the influence of different positions of spandrels and fire canopy on fire hazard and smoke. This study finds out the following: fire canopy can better prevent the longitudinal spread of fire smoke than spandrels. The fire canopy above spandrels can reduce the flue-gas temperature. The higher the spandrels above floors, the faster the temperature of the central lines of glass curtain walls above fire floors reduced. However, the higher the spandrels above floors, the more uneven the distributions of high-temperature regions and low-temperature regions, thus leading to the increase in horizontal temperature differences of glass panels. This research conclusion can be taken as a reference for fire protection design of super high-rise glass curtain wall.

The Road to the Salvation of Mankind: Additions to the Series of Glass Designs by the Crabeth Brothers

The two newly-discovered drawings by the glass painter Dirck Crabeth presented here fit seamlessly into his series The Road to the Salvation of Man, which has long been known. The drawings are the design for the first episode, until recently known only as a glass panel, and the original of the second episode, the copy of which, along with two copies of other episodes are in Museum Catharijneconvent in Utrecht. Stylistic clues have made it possible to date Dirck Crabeth’s drawings and the corresponding surviving glass panels earlier, to around 1545-50. They share the thinking represented in a Lutheran series of prints by Frans Huys dating from around 1560 to a design by Gerard van Groeningen, which was discussed by Daniel Horst. An analysis of the career of the young Wouter Crabeth, his collaboration with Dirck and characteristics of their different styles demonstrates that the three copies in Utrecht could be by Wouter Crabeth, contrary to the recent attribution by Ilja Veldman to the Antwerp artist Pieter Huys, Frans’s brother, and in line with the previously held attribution to one of Dirck’s assistants.

Strengthening Thermal Stability in V2O5-ZnO-BaO-B2O3-M(PO3)n Glass System (M = Al, Mg) for Laser Sealing Applications

Today, the most common way of laser sealing is using a glass frit paste and screen printer. Laser sealing using glass frit paste has some problems, such as pores, nonuniform height, imperfect hermetic sealing, etc. In order to overcome these problems, sealing using fiber types of sealant is attractive for packaging devices. In this work, (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glasses (mol%) incorporated with xM(PO3)n concentration (where M = Mg, Al, n = 2, 3, respectively) were fabricated and their thermal, thermomechanical, and structural properties were investigated. Most importantly, for this type of sealing, the glass should have a thermal stability (ΔT) of ≥80 °C and the coefficient of thermal expansion (CTE) between the glass and panel should be 1.0 ppm/°C. The highest thermal stability ΔT of the order of 93.2 °C and 112.9 °C was obtained for the 15 mol% of Mg(PO3)2 and Al(PO3)3 doped glasses, respectively. This reveals that the bond strength and connectivity is more strongly improved by trivalent Al(PO3)3. The CTE of a (70-x)V2O5-5ZnO-22BaO-3B2O3-xAl(PO3)3 glass system (mol%) (where x = 5–15, mol%) is in the range of 9.5–15.5 (×10−6/K), which is comparable with the CTE (9–10 (×10−6/K)) of commercial DSSC glass panels. Based on the results, the studied glass systems are considered to be suitable for laser sealing using fiber types of sealant.