ASTM Glass Engineering

[NFExp]

All

I have been asked to size the thickness of store front glass. The glass panel is 6 w'x10 h'. The panel is supported on top and bottom only. In the past, I have always used the ASTM1300.. For this project the 10' is beyond the limitations of the chart.. See attached PDF.

For reference the builder said they wanted to use 9/16 laminate and that they have used that thickness for similar projects. Per the chart, a 10' length of glass would fail in deflection for all thicknesses. Before I tell the architect they need a bunch of mulls, I am hoping I can find another reference

I feel like I must be missing something since I feel like I see 10' tall store fronts all the time, Any help will be appreciated.

 

[jjl317]

Exterior? If so, I think the issue may be top and bottom support only - if designed at all, I generally see storefronts with vertical mullions included. Then glass is four side supported and not really an issue.

 

[RenHen]

I'm working on some near identically sized storefront glass right now & ended up telling my client that they could not get by without vertical members for a 10' tall 9/16" laminate exposed to exterior wind loading. I regularly design similarly sized storefronts without vertical members, but my analysis calls for thicker glass for those.

I'm not aware of any other references that would be helpful, and at least in the markets I work in, the ASTM E1300 is the Building Code Referenced Standard for glass design so it can't really be avoided, but it does provide alternate analysis methods & equations in the appendices for cases that fall outside of the tables. They won't give you a different answer but will give you a way to quantify things.

 

[NFExp]

RenHen

Thanks for your response.. Based on the chart, I cannot get any thicknesses to work for a 10' height.. Even for a 3/4" panel, the 28psf wind load results a deflection of over 1.5" and my limitation per ASTM is L/175 which is 0.68"..

 

[RenHen]

I'd reread the section you got L/175 from in the ASTM E1300. That's a deflection limit for the framing members to match the assumptions for "support" that the 2, 3, 4-side supported tables are based on, not a limit for the glass itself. I expect you'd still have issues with stress for that glass makeup in this configuration though.