Numerical assessment of laminated cantilevered glass plates with point fixings

Cantilevered laminated glass plates, used e.g., in balconies and freestanding glass balustrades, are an example of the use of glass in modern architecture as a structural material. In order to fulfil its scope of preventing building occupants from failing out, the cantilevered plate must be able to transfer the loads imposed from the crowd pressure or by people in motion to the main structure of the building. Since a cantilevered plate is critical in the joint, the design of the connection between the glass pane and the supporting structure is of primary importance for the performance of the system. The paper investigates the behaviour of cantilevered laminated glass plates with point joints, accounting for both bolted and adhesively bonded fixings, and different designs of the joint system. The static and impact tests prescribed in the Italian standard UNI 11678 are numerically simulated and the results analysed in terms of the horizontal deflection and maximum peak stress of the glass pane. Under static loads, bonded joints reduce stress concentration and increase the lateral stiffness of the cantilevered plate in comparison to bolted fixings, but the results are highly sensitive to the stiffness of the interlayer. Increasing the vertical distance between the fixing rows is shown to have contrary effects on the stress concentration around bolt holes depending on either static or dynamic loading is considered.