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Existing 30ft Tall Warehouse - Lateral System

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JNEnginr

JNEnginr

Civil/Environmental
Aug 26, 2008
99
Hey Everyone!

Here's what I'm dealing with:
-200ftx600ft Existing Warehouse, 30PSF Snow Load, 115MPH Wind, Seismic B - It's prefab, but not the typical A-Frame, Z-Roof Purlins, etc
-35' tall
-LH Steel Bar joists spanning +/- 38ft
-At the interior, bar joists supported by Joist Girders spanning +/-38ft (T shape steel top and bottom chords, steel angles as webs)
--Joist girders supported by a CMU pier, 16x16, going up +/- 30ft. (There's electrical outlets in the pier...not sure how)..Not sure if there's a steel column inside, but at the top, it's just a bearing plate that the JG sits on.
-At Exterior and around the perimeter, Joists sit on steel i-beam, which spans 18ft from steel i-beam column to column. Some columns are encased in CMU, others are exposed
-Exterior Wall construction is metal panels (not exactly sure what these are, they look like 12" wide by full height "planks" that somehow interlock), supported by Z-Purlin Wind Girts, spaced at +/-10ft o.c., that are hung with a vertical threaded rod from the end roof joist.
-There is NO cross bracing. Anywhere.

What's the lateral resisting system? Can the exterior Metal Panels be a "Shear wall"? Z-Purlins seems to be fastened to them at +/- 6" o.c.

Thanks for your insight! I can upload photos too.








 
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Any bracing in the roof? Does it look like the roof was designed as a diaphragm by spacing of deck attachments. How is roof slope handled? On the 600' length, is there no intermediate x-bracing on the interior? any building expansion joints. With 30 psf snow, you may be subject to cooler weather than Florida. How long has it been standing? The metal panel system can be designed as a lateral restraint; how are the panels attached to each other. 30' is tall... but I've done 40' clear for a 400,000 sqft cargo terminal building. Is there any moment connection between the roof girders and the columns? Lots of questions.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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dik - No cross bracing in the roof, just bridging between the bar joists. Roof is metal deck, so i assume that's the diaphragm used to transfer loads to supporting elements. I did originally mean no cross bracing in the exterior walls. No expansion joint. No Interior X-Bracing. Roof slopes to the exterior walls from a high point at the center. Looks like it's from the 80s but no way to be sure. Its in New Jersey. No plate going across the girders to suggest a moment connection. Bottom chord of the JG stops short of the pier. No really sure how the metal wall panels are attached to each other, but looks like they lock into each other. And update, the structure is 280ft x 360ft.

PXL_20221115_160353464_so0wes.jpg
PXL_20221115_154655887_ediwqu.jpg
PXL_20221115_152953181_i2ypbx.jpg
PXL_20221115_152059119_kmuezr.jpg
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None of that looks like lateral resistance. What is the wall and roof construction... it almost appears to be precast of some kind, but I couldn't see any inter panel connection. Is the masonry only used to enclose steel columns? 4x8 CMUs? On the exterior, the beam is not centered on the CMU pier. First step is to determine if the warehouse if adequate for lateral loadings. These may have changed since it was originally constructed. What is the purpose of the new engineering work?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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Can the exterior Metal Panels be a "Shear wall"?
Click to expand...

No. They don't have intermediate supports for out of plane forces except hung girts, holdowns, or anything that looks like it was designed for lateral resistance. And if it was built in the 80's, this was before proper research into metal panel shear walls began.

New Jersey's code enforcement is historically not very strong. You could easily get away with no lateral system structures back in the day.
 
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msl... for a 280'x360' building? Using cladding and roof for diaphragm wasn't common back in the 80s. Just small enough for no mid length expansion joint...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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JStructsteel said:
Cantilevered masonry columns???
Click to expand...

That's what I'm trying to determine...is that a thing? New Warehouse was constructed next door, taller, and has these 40ft tall concrete columns, JG sitting on top of them.

dik said:
What is the wall and roof construction
Click to expand...

It's not precast concrete, it's just these metal wall panels. At the perimeter, i believe its 4x8s CMU around a steel column, but i don't think that's the case in the interior.

Owner wants to put on another addition on the front and side of the existing structure. Wants to remove the previously exterior wall panels/wind girts to access the new building. If I saw cross bracing, I'd be like ok, stay away from that, but I don't see anything.

So I'm left wondering, are the wall panels the lateral system? Or is all the load sent into the masonry interior columns, like flag poles in the ground.
 
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I'd check it out before doing any alteration. It might be 'iffy'. Concern would be altering the perimeter 'bracing' 'lateral support system' in any fashion. Renovation may 'trigger' a bunch of unintended and costly consequences.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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I did a small concession type building for a baseball field with cantilevered CMU columns. Obviously not the scale this is, and I had 4 of them and beams connecting them, so really more of a frame.

Figure the load on each column, see if they work. I would assume the interior ones too.
 
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XR250 said:
moment frames at the perimeter?
Click to expand...

I don't think so. In the last pic, you can see the steel column runs up, and the perimeter girders beams just run almost behind it, and bolt into it thru the beam web/column flange.
 
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