Evaluation and optimalisation of adhesive point fixings in structural glass

The aim of this research is to develop a design method for an adhesive point fixing between glass and metal. The first step in this development is a literature study on point connections between glass and metal in general (including bolted connections). The purpose of this review is to compose a list of parameters that influence the bond strength. The second step is an experimental study where the test specimens are tested while varying the different parameters. The third step is to create a numerical model. This model is built based on the results of the experimental study. With this model the influence of each parameter on the strength of the connection can be determined. Finally, combined with a control guideline for adhesive point fixings, a design method can be developed for adhesive point fixings

Numerical research on stiff adhesive point-fixings between glass and metal under uniaxial load

Adhesive point-fixings are being used more frequently because of their numerous advantages compared to traditional bolted connections, such as a better load introduction, the absence of drilled holes in the glass, and increased thermal performances. With this research the mechanical behaviour of adhesive pointfixings between glass and metal under uniaxial load is investigated numerically. By supporting the model pivotally along a circumference equal to six times the diameter of the fitting, the entire connection is investigated. Up to now, only the adhesive layer has been studied, without bringing the influence of the stiffness of the glass panel into account. With a finite element method (FEM) a numerical model is validated by experimental results. A complete validated model is gained by performing the experiments for five different geometries with a relatively stiff adhesive. The obtained FEM model is then used to study the influence of geometrical parameters, such as the connection’s diameter and glass thickness, and material parameters, such as the adhesive modulus of elasticity, on the mechanical behaviour of adhesive point-fixings under uniaxial load. Themaximal occurring stresses in the glass panel and adhesive layer will increase with a decrease of the connector diameter, the glass thickness and adhesive thickness, and with an increase of the adhesive stiffness. Furthermore, the maximal deformation of the glass panel can be reduced by increasing the glass thickness and adhesive stiffness, and by decreasing the connection diameter and the adhesive thickness

Evaluation of the SLG method for applications with adhesive point-fixings

Glass plates connected with adhesive point-fixings are stronger than when connected with traditional bolted point fixings. For the investigation of glass plates with adhesive point-fixings a complex FE model is required. However, a simple analysis method is preferred. We developed a method based on the SLG-method for bolted point-fixings to simplify the finite element analysis. This is done by separating the glass plate into a local and global component. The local component represents the adhesive point fixings and is built with more complex FE volume elements. The global component represents the entirety and is built with less complex FE shell elements. The total result can be obtained by superposition of the results of the local and global component. In this document it is described how we developed and validated this method. The results show that the superposition is a suitable method. Consequently the investigation of glass plates connected with adhesive point-fixings is simplified

New glass design method for adhesive point-fixing applications

Stress concentrations in glass plates connected with adhesive point-fixings are much lower than when connected with traditional bolted point-fixings. For the investigation of adhesive point-fixings a complex finite element model is usually required. Based on the SLG-method for bolted point-fixings, a design method is developed for adhesive point-fixings to simplify the finite element analysis. This is done by separating the glass plate into a local and global component. The local component represents only a part of the glass plate with one adhesive point-fixing and is modelled with more complex finite element volume elements. The global component represents the entirety and is modelled with less complex shell elements. The total stress distribution is obtained by superposition of the results of the local and global component. This paper describes how this method is developed and validated. The local numerical model is calibrated based on strain measurements obtained from experiments. The results show that the SLG-method can be suitable for adhesive point-fixings as well, which enables a simplified and faster design

Numerical research on the mechanical behavior of adhesive point-fixings under shear

Adhesive point-fixings are being used more frequently because of their numerous advantages compared to traditional bolted connections, such as a beter load introduction, the absence of drilled holes in the glass, and increased thermal performances. This paper describes the numerical investigation of the mechanical behavior of adhesive point-fixings under shear. The numerical model is based on the method of superposition of local and global components, i.e. the SLG-method, developed by Beyer. This superposition of global and local components implies that the investigation can be limited to the local area. By supporting the model pivotally along a circumference equal to six times the diameter of the fitting, the entire connection is investigated. The finite element model (FEM) is validated by experimental results. To gain a validated model, the experiments are performed with a load eccentricity of 15 mm and two different types of adhesives (MS-polymer and epoxy). The obtained FEM is then used to study the influence of geometrical parameters and material parameters on the mechanical behavior of adhesive point-fixings under shear. From the results, it can be concluded that the maximal stresses occuring in the adhesive layer and glass panel will increase with a decrease of the connector diameter and adhesive thickness, and with an increase of the load eccentricity and adhesive stiffness

Influence of corner and edge distance of adhesive point-fixings for glass structures

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A preliminary study of the nonlinearity of adhesive point-fixings in structural glass facades

The recent demand for architectural transparency has drastically increased the use of glass material for structural purpose. However, connections between structural glass members represent one of the most critical aspects of glass engineering, due to the fragile behaviour of this material. In that respect, research activities on adhesive point-fixings are currently on-going. The mechanical behaviour of adhesive point-fixings is affected by large nonlinearities, which are usually investigated by nonlinear Finite Element Analysis (FEA). This paper focuses on the geometrical and the material nonlinearities of adhesive point-fixings for glass structures. Firstly, the nonlinear material behaviour of two selected adhesives are investigated by means of uniaxial tension and compression tests on the bulk material. The production of specimens, test methodology and displacement rate dependency are discussed. Secondly, the nonlinear stress distribution occurring in the adhesive and the joint stiffness is investigated by means of nonlinear FEA. The effects of several parameters on the mechanical behaviour of adhesive point-fixings, such as the connection dimensions and adhesive elastic properties, are studied. The adhesive stress-strain curves resulting from the experimental campaign show that the adhesives exhibit a large nonlinear behaviour. The results show that the stress and strain at failure reduce as the displacement rate is reduced. From the numerical investigations it is concluded that large nonlinearity involves the mechanical behaviour of adhesive point-fixing which cannot be neglected. The stress distribution within the adhesive deviates from uniform nominal stresses, even in case of simple load condition, with stress peaks up to four times higher than nominal stresses.</span

Determination of the material properties of an epoxy and MS-polymer for adhesive point-fixings

Adhesive point-fixings are being used more frequently because of their numerous advantages compared to traditional bolted connections, such as a better load introduction, the absence of drilling holes in the glass and increased thermal performances. For the analysis of such fixings the use of finite element analyses is necessary. The adhesive properties in these finite element analyses are presented on the basis of stress-strain curves. The determination of the stress-strain curves is done by experimental testing on bulk material of the adhesive. With these tests the displacement rate reliance can also be studied. In this contribution, the fabrication and testing of test samples is described for two selected adhesives. The experimental data show that the selected adhesives behave stiffer under tension as the displacement rate is decreased

Numerical investigation of reinforced laminated glass beams

Glass is increasingly being used to create transparent structural elements such as columns, beams, floors, etc. Especially in case of glass beams, a significant amount of investigations has been performed to improve the unsafe (brittle) failure behaviour of glass. Similar to reinforced concrete, reinforced glass beams have been developed in which stainless steel is added to the glass laminate to obtain a safe failure behaviour. The concept has been proven to be feasible when assuming statically determinate systems. However, the additional system safety of statically indeterminate systems has not been investigated yet. This paper presents numerical research outcomes on reinforced glass beams with statically determinate as well as statically indeterminate support conditions. From the results, is is concluded that it is feasible to apply such beams in statically indeterminate systems as significant system safety and a safe failure behaviour was observed