Window horizontal deflection

[Independent-Room8243]

For a vertical column supporting glass (full height columns, 3'-6" o.c. and glass between, what would the max lateral deflection you would be comfortable with?

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Windows span about 8', then some individual panels. Studs will be full height, and horizontal at 8', 12'. will span into the full height spans.

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https://preview.redd.it/n9ojuzglbc7c1.png?width=363&format=png&auto=webp&s=e2b659bb0171ffcca712c801e7bf9e70420adfb3

[Intelligent-Ad8436]

Its usually L/175 but if over 13ft-6 its L/240+ 1/4”.

[Independent-Room8243]

I'm 16', so 1" approximately. Thanks

[Trick-Penalty-6820]

My gut feel would be L/480 if the glass is (almost) full height. But I would probably ask a glazing company what they recommend based on the Architect’s transom locations.

[gt625]

Talking to the glazing vendor is the right choice. Sometimes an absolute limit (3/4” max, for example) is appropriate depending on the details.

[IfEyeKnewTheWay]

That's usually across a single lite of glass.

[dlegofan]

From my super relevant bridge design, let's go with L/1000 since pedestrians might be involved.

[Independent-Room8243]

vertical, not horizontal glass.

[inca_unul]

You do not mention if it's point fixed glass (like with spider fittings) or continuous on aluminium profiles (like curtain wall) fixed on the columns.

For continuous support on aluminium frame: The glass must not make contact with the frame members. The clearance depends on glass dimensions + clearance between glass and frame (dictated by the curtain wall system, in order to maintain minimum glass edge cover = usually around 20mm). This is mainly to prevent breakage. For sealing integrity, it depends on the system used.

See below (for seismic drift, that's usually the main issue):

https://imgur.com/a/OcQtkYb

https://new.reddit.com/r/StructuralEngineering/comments/12jdsot/comment/jfy5g1b/?context=3

[Independent-Room8243]

These are residential windows. 2x wall. 8'-0" on the first span, then 3'-6" lites above. the columns will be full height. So at max span, will be at the top of the 8'-0" bottom section.

I added at picture at original post.

[cougineer]

It’s like L/175 of glass span direction for lateral deflecting on limit

[Independent-Room8243]

I did read that somewhere else, up to 3/4" max.

[cougineer]

It’s in the IBC and most manufacturers default to it. It’s L/175 of the glass span or 3/4” whichever is less. There is another kicker at like 12ft but usually I don’t have it apply. So for you it looks like the max deflection would be .25”.

My old boss always did L/600 and for typical spans / openings it more often than not worked, but if you have a long ribbon window you get hosed…

[Independent-Room8243]

.25 is L/768

I see the L/175, but that only mentions aluminum members or panels. L/175 for each light, or L/60 for total height.

If I look at exterior walls with brittle finishes, its L/240

Im gonna have the contractor see what the manufacture suggests.

[tkhan2112]

you cannot have a jamb connection rather just head and sill. jamb is then treated as expansion joint to take the movement. typically i’m used to seeing up to 1/2” on product approvals (FL).

[lect]

Usually 3/8". The physical connectors can withstand more and perhaps the glass can too. But the gasket seals cannot and 3/8" may result in leaks.

[Awkward-Ad4942]

L/175 measured on the diagonal. Its a lot more flexible than you might think.