Development of adhesives constitutive material laws for the assessment of bonded steel to glass partial composite beams

Glass products are widely employed in transparent facade and roof structures as tertiary non-structural elements despite their large in-plane compressive resistances. To structurally implement them in building, tensile stresses must be consequently reduced or avoided. The later requirements would be fulfilled by realizing composite steel to glass connection, whose principal difficulty would arose from the connection mean which should be sufficiently rigid to transfer shear forces and sufficiently soft to not alter the glazing. Two possible jointing methods were envisaged and investigated to accomplish this assembly and overcome this problem, i.e. a linear adhesive bonding of the steel and glass parts and a mixed mechanical-adhesive connection. In consequence, two potential adhesives were selected, a silicone elastomer and a UV-curing acrylic thermoset. A lack of knowledge with regards to their mechanical properties implied the conduction of several series of quasi-static, cyclic and long-term relaxation tests. The possible influence of external parameters, such as temperature, humidity or UV-radiation, on their uniaxial tension/compression and shear behaviours was evaluated with the help of statistical methods applied on the results of Taguchi design of experiments tables. With the invariance of the silicone properties, a new hyperelastic quasi-incompressible constitutive material law accounting for the quasi-static and post Mullins effect behaviour was developed and validated with finite element analyzes of the small-scale experimental tests. The UV-acrylic was however found strongly dependent on the loading rate and one-dimensional models were suggested to describe the quasi-static tension and shear behaviour under specific rates. In reason of the poor long-term properties of the UV-acrylic, only the silicone was regarded for the construction of the two types of composite beams. Pre-evaluations issued from numerical simulations including the developed material law accommodated perfectly with theoretical data and approached the large-scale tests results by considering the manufacturing operations conducted on the steel beam.