The use of Structural silicone glazing (SSG) systems in large commercial glazed facades is well established in current practice, mainly due to the architectural aspiration of having a continuous smooth glass surface across the building elevation. Enhanced thermal and security (blast) performance are typically listed as an advantage for this particular type of systems.
SSG façade systems are structurally complex due to the fact that multiple load-paths can be identified within the system. It is accepted as good practice to detail façade panels so that the dead load of the glass is not carried through the structural silicone. But can this be achieved in reality? The aim of this paper is to identify and discuss challenges with the assumption that the SSG is isolated from the glass self-weight and provide a better understanding on the complexity of SSG systems.
The influence of stress/strain and creep due to thelong-term load on the system capacity will be investigated. Some degree of long term loads are usually present due to detailing and real system behaviour. Real project examples will be used to identify opportunities for improvement and findings will be summarised at the end of the paper.
Quality control is the most critical element to ensure that the sealant performs. Therefore, SSG is typically applied in the controlled environment of a production facility, where external factors such as dust, temperature and relative humidity can be controlled and monitored. SSG manufacturers have specific procedures and recommendations that must be followed to ensure proper adhesion, curing and joint fill.
When designing structurally glazed unitized systems the effect of permanent loads (glass self-weight) is typically ignored. It is assumed that structurally glazed systems behave in the same way as capped systems. In capped systems the glass pane bears directly onto the shoes, then the load is transferred from the transom up the mullions through the corner mullion/transom fixing and finally the dead load is transferred back to the main structure through the bracket.
Structural behavior of SSG systems under gravity loading
The frame is placed horizontally on a working bench
The glass is installed on the frame.
- Frame is cleaned, primed and the structural silicone glazing is applied
Once the silicone is cured, the unit is moved to the stockage area.
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