Glass Breakage in Insulated Glazing Units in Spandrel Assemblies

Start Date: Thursday, November 12th, 2020
Time: 3:00 - 4:00 pm
RSVP Date: Wednesday, November 11th, 2020
Registration: Register Online

Recent years have seen an increase in the use of insulated glazing units in spandrel applications. There have been increased instances of glass breakage attributed to thermal stress for this type of design especially when the glass is treated with ceramic frit. These spandrel applications see higher thermal stresses than with traditional single glazed spandrels and that venting the spandrel cavity has been shown to do little to minimize this increase. Recent research supports the theory that the increased in thermal stress is leading to breakage of the inner light due to the lowered strength of heat strengthened ceramic opacified glass. Simulations with 3-D thermal and CFD were implemented to predict the temperature difference that cause the thermal stresses in spandrel assemblies.  In response to this phenomenon considerations are being given to using fully tempered glass for the inner light when using a ceramic frit opacifier. The result of testing of structurally glazed IGUs with a shattered fully tempered inner light demonstrated the residual strength was sufficient to resist an initial application design wind loads. The performance testing of ceramic frit were compared to silicone opacifier shows that these coating do not reduce the strength of the glazing.
Learning Objectives
1.    Learn the conditions that lead to increased glass breakage in spandrel assemblies with insulated glazing units and how to distinguish them from other glazing failures.
2.    Explore the limitations of venting spandrel assemblies and how computer simulations can be used to predict the glass surface temperature differences that can lead to increased risk of breakage.
3.    Review the potential limitation of using fully tempered glass in lieu of heat strengthened glass for the inner light of insulated glazing units in spandrel assemblies.
4.    Contrast the performance of silicone opacifier as an alternate to ceramic frit in spandrel assemblies.

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