LATERAL DEFLECTION FOR GLASS
LATERAL DEFLECTION FOR GLASS
(OP)
What horizontal deflection criteria do you use for glass / windows?
IBC 2009, 2403.3 Framing. To be considered firmly supported, the framing members for each individual pane of glass shall be designed so the deflection of the edge of the glass perpendicu1ar to the glass pane shall not exceed L/175 of the glass edge length or 3/4 inch (19.1 mm), whichever is less, when subjected
to the larger of the positive or negative load where loads are combined as specified in Section 1605.
L/175??? I’ve always considered glass to be one of the more “brittle” materials that should require L/360 or L/600.
The Weyerhauser “U.S. Wall Guide” also recommends L/175, which, of course, is referenced back to IBC.
Here is what I’ve used in the past: (Please comment)
HORIZONTAL DEFLECTION CRITERIA
L/600 = Lat. wind on vertical element w/glass or brick
L/360 = Lat. wind on vertical element w/glass or brittle finish
L/240 = Lat. wind on vertical element w/semi- brittle finish
L/120 = Lat. wind on vertical element w/flexible finish
Thank you!
IBC 2009, 2403.3 Framing. To be considered firmly supported, the framing members for each individual pane of glass shall be designed so the deflection of the edge of the glass perpendicu1ar to the glass pane shall not exceed L/175 of the glass edge length or 3/4 inch (19.1 mm), whichever is less, when subjected
to the larger of the positive or negative load where loads are combined as specified in Section 1605.
L/175??? I’ve always considered glass to be one of the more “brittle” materials that should require L/360 or L/600.
The Weyerhauser “U.S. Wall Guide” also recommends L/175, which, of course, is referenced back to IBC.
Here is what I’ve used in the past: (Please comment)
HORIZONTAL DEFLECTION CRITERIA
L/600 = Lat. wind on vertical element w/glass or brick
L/360 = Lat. wind on vertical element w/glass or brittle finish
L/240 = Lat. wind on vertical element w/semi- brittle finish
L/120 = Lat. wind on vertical element w/flexible finish
Thank you!






RE: LATERAL DEFLECTION FOR GLASS
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: LATERAL DEFLECTION FOR GLASS
I'm not an expert on glass, so that's all I can think to do. Your listed criteria for the other categories of finishes appear solid and similar to what I've generally used.
RE: LATERAL DEFLECTION FOR GLASS
Glass is brittle, but it also has about 1/3rd young's modulus of steel.
RE: LATERAL DEFLECTION FOR GLASS
Codes usually do not say what the allowable deformation is
You can even go below L/100 ....
Stress must be check separate
best regards
Klaus
RE: LATERAL DEFLECTION FOR GLASS
http://industry.glass.com/USGlass/2001/0106/deflec...
RE: LATERAL DEFLECTION FOR GLASS
Would say unless you've got a curtain wall or glass consultant telling you otherwise that it would be prudent to stick to those limits for the supports though. I would imagine the vast majority of off-the-shelf glass products assume they're fully supported on all four sides.
RE: LATERAL DEFLECTION FOR GLASS
RE: LATERAL DEFLECTION FOR GLASS
oh....we go below L/100 if necessary ....
Big facade glass panels ...
best regards
Klaus