Structural steel–glass facade panels with multi-side bonding – Nonlinear stress–strain behaviour under complex loading situations

Today in practice, finite element analyses (FEA) are used to design modern structural steel–glass facade panels showing multi-side bonded joints with a complex geometry, because no reliable analytical methods are available for calculating such occurring complex multi-axial stress states. However, experiences show great deviations between experimental and numerical results, which may lead on the one hand to significant over-dimensioning, but on the other hand – more critical – to unexpected cases of damages. For applications of facade panels with multi-side bonding, mainly hyper-elastic adhesives are used. The aim of this work is to show the possibilities existing hyper-elastic material models provide for specific steel–glass components and where and under which circumstances these in many FE programs given material models fit best the true behaviour observed in large-scale component tests. To this end, three testing levels have been introduced to investigate the adhesives within multi-side bonding. Small-scale tests have been performed to characterise the adhesives and to determine the material model for subsequent FEA. After that component tests with two different loading situations have been performed to investigate both a complex and a simpler stress state within the adhesive. This paper focuses on both component tests and evaluates the results from these tests. For thin glass thicknesses (here 6mm) the FEA with hyper-elastic material models provide results in very good compliance with the experimental results. When increasing the glass thickness (here 10 and 15mm) the influences of the non-linear adhesive characteristic to the total structural behaviour decreases, which leads to rather high deviations from the experimental results.