In this study tempered glass/mild steel joints with bolted and adhesive shear connections are investigated. However, a thorough experimental and numerical assessment of bolted versus bonded joints including the joint’s failure prediction is currently lacking. 2016) has shown that the use of stiff adhesive glass joints can be extended to real-life building construction. Recently, the Crystal Houses façade project (Oikonomopoulou et al. In their study, they also considered different glass surface treatments and the long-term performance of the joints.
Industrial strength double sided mounting tape series#
Machalicka and Eliasova ( 2017) also performed a series of tests with adhesive joints connecting glass-glass, glass-steel and glass-aluminium. In addition, extensive research has taken place on the use of adhesively bonded point fixings in canopies and facades (Belis et al. Single lap steel-glass connections have been tested in the past, comparing the performance of different adhesives while using different modelling approaches (Nhamoinesu and Overend 2012 Overend et al. Several research groups have investigated adhesive glass connections and related modelling approaches.
It is currently unclear how adhesive characteristics influence the strength of hybrid glass/steel joints. 1997), but are relatively unproven in applications relating to structural glass (Haldimann et al. On the other hand, stiff and high strength adhesives such as acrylics and epoxies have been used in other industries, for example as structural adhesive joints in FRP composite materials (Adams et al. Soft elastic adhesives like silicone are being used extensively in glazing systems for gap-filling roles, but are rarely used for load-carrying structural connections (IStructE 2014). Adhesives can exhibit a wide range of mechanical properties depending on their chemical classification and curing mechanism.
Unlike conventional mechanical joints, adhesive joints do not increase the weight of the structure and have aesthetic advantages since they offer uninterrupted and smooth surfaces and possible transparency. In contrast, adhesively bonded joints have structural advantages as they minimize the development of high stresses, as well as avoid the formation of additional surface flaws. While bolted joints have been and are still being used extensively, they lack structural efficiency and reliability as the drilling/cutting required may introduce flaws and discontinuities on the glass surface (Haldimann et al. Areas of stress concentration, such as load introduction or connection points, are particularly dangerous for any glass structure due to the material’s inability to plastically deform. Failure of glass can happen without any warning in a catastrophic manner once the critical fracture toughness is exceeded, with failure originating at small surface cracks or internal flaws. One of the main challenges when using glass as a structural material is its brittleness. However, a number of challenges related to the structural use of glass still remain, such as the uncertainty of glass strength, the lack of design standards and, most importantly, the lack of an effective and durable connection method to other structural building materials such as steel (IStructE 2014). Over the last decades the use of glass in the building industry has increased significantly. The numerical analyses highlight that while brittle adhesive joints fail once the fracture strain of the adhesive has been reached, while for ductile adhesives an extensive plastic zone develops near the areas of stress concentrations thereby delaying the damage initiation. The results show that both types of adhesive joints outperform bolted joints while counter-intuitively the lower strength ductile adhesive achieves consistently higher joint strength compared to the brittle adhesive. Good agreement between the experimental observations and numerical predictions is achieved. Pressure-sensitive, plasticity and failure models are introduced and calibrated to accurately capture the behaviour of the adhesives. In addition, material characterisation testing for the glass and the adhesive is performed and the outputs are used for the numerical simulation of the same joints. The designs consist of tempered glass and aluminium substrates while steel splices are used for the load application. Two benchmark designs of shear connections are introduced and tested experimentally in quasi-static tensile tests. This paper investigates the use of bolted and brittle/ductile adhesive connections in glass structures. Source: Glass Structures & Engineering 3, 183–196 (2018). Authors: Ioannis Katsivalis, Ole Thybo Thomsen, Stefanie Feih & Mithila Achintha
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