Vaulted Window Wall Lateral Design

[GaStruct]

I have a 16' tall window wall where I initially specified 24" Simpson Strong-walls on each end. The wall widths were changed to ~12" in the field and the contractor installed this instead. See attached photo.

Installed is a (3) 11 7/8" LVL column on each side (other side not pictured) with straps at each header and (2) hold downs on the bottom. If you analyze this just as a cantilevered column system, then obviously the hold down reactions don't calc out to be adequate. I would like to look at this as a two-story portal frame type system but I am unsure how to keep the joints at the headers stiff enough.

Does anyone have any ideas for modifications to get this to work? Lateral load is small. About 2 kips total.

(Please ignore the hinge in the wall. That will be fixed.)

 

[XR250]

2k is a lot to deal with here. Any way to justify a 3 sided building model? Can't see you making this work easily without going back to the OG design.
Maybe adding some large red iron plate angley things screwed to the face of the beams.

 

[GaStruct]

3 sided open front could maybe work. The other sides are a vaulted hip roof so diaphragm discontinuity comes into play.

A plate connecting the headers to the column could work. They would need to fur the wall out though.

 

[XR250]

A plate connecting the headers to the column could work. They would need to fur the wall out though.

I would think that is the least of their problems.

 

[bones206]

Chapter 14 of Malone's book covers a method of analysis for wood rigid frames, but... good luck. The time spent on analysis would be hard to justify.

I imagine you consider the entire depth of wall between the windows as a deep flexural beam that could be quite stiff, especially if you sheath the interior as well. Whether it's enough is hard to say. The skinny columns are the limiting factor I think.

 

[GaStruct]

bones206​

The time spent on analysis would be hard to justify.

Couldn't agree more. I get tons of residences with crazy amounts of glass and my fee is never enough to justify a complex analysis that would require special detailing.

bones206​

I imagine you consider the entire depth of wall between the windows as a deep flexural beam

Not quite sure I follow how the load gets resolved looking at the wall segment as a beam. Also, the load comes in at the top plate

 

[bones206]

Sorry, I'll try to clarify. I was idealizing the wall as a 2-story rigid frame, with a shallow top beam at the roof and deep middle beam between the windows. I imagine the deep middle beam would attract most of the lateral load due to it's flexural stiffness relative the the rest of the rigid frame members.

Getting the beam end moments into the column/wall segments is resolved through careful detailing of the "panel zone", as Malone calls it. I've never tried to do this myself, so I don't have a good feel for feasibility in this case. When I first read that book a few years ago, I got to that chapter and said "nope!"

By the way, anyone have the new 2nd edition? The price came way down so I was considering getting it if it's a worthwhile investment.