Experimental investigations of statically indeterminate reinforced glass beams

A lot of 'hybrid' structural glass beam concepts were developed in the past years to overcome the brittle failure behaviour of glass. These beams possess a safe failure behaviour through post-fracture strength and ductility. Promising is the concept of reinforced laminated glass beams in which stainless steel reinforcement sections are included in the glass laminate and provide a post-fracture load-carrying mechanism. This type of beams was extensively tested in three- and four-point bending for a variety of environmental conditions (e.g. temperature and humidity), geometrical scale, reinforcement percentage and element robustness. The concept proved to be satisfying. In addition to element safety, today's buildings also require significant system safety. This paper presents an experimental test programme in which the load-carrying behaviour of statically indeterminate reinforced laminated glass beams is investigated. The beam specimens were tested in five-point bending (three supports and two load points) at 23 °C and 60 °C, at a humidity level of 55%. In addition, two different reinforcement percentages were investigated. The beams illustrated satisfying failure behaviour in all cases, proving the effectiveness of applying reinforced laminated glass beams in statically indeterminate systems. The effect of temperature is primarily observed in the fractured and plastic phases. There, the specimens at 60 °C illustrated lower bending stiffness and slip of reinforcement, which resulted in a lower post-fracture strength. The temperature effect was larger for the beams with high reinforcement percentage. The load-carrying behaviour and load redistribution were highly dependent on the reinforcement percentage. A higher reinforcement percentage resulted in higher bending stiffness in all phases of the model. In addition, a higher initial failure load, yield point and post-fracture strength was achieved. Finally, also a different collapse mechanism was observed for both tested reinforcement percentages.