Design of Mechanically Reinforced Glass Beams: Modelling and Experiments

The present paper is a study on how to obtain a ductile behaviour of a composite transparent structural element. The structural element is constructed by gluing a steel strip to the bottom face of a float glass beam using an epoxy adhesive. The composite beam is examined by four-point bending tests, and the mechanisms of the beam are discussed. Analogies to reinforced concrete beam theory are made; thus, four different design criteria, depending on the reinforcement ratio, are investigated. Analytical expressions are derived that are capable of describing the behaviour in an uncracked stage, a linear cracked stage and a yield stage. A finite element model, capable of handling the cracking of the glass by killing elements, is presented. Both analytical and numerical simulations are in fairly good agreement with the experimental observations. It appears that the reinforcement ratio is limited by the risk of anchorage failure and must be adjusted accordingly to obtain safe failure behaviour in a normal reinforced mode. Analysis of anchorage failure is made through a modified Volkersen stress analysis. Furthermore, different aspects of the design philosophy of reinforced glass beams are presented.