Removing End Bays in an Old PEMB 2

[structuralengr89]

As the title implies, I have an old PEMB that has experienced significant settlement in the last 2 bays due to expansive soils. The owner doesn't have the money to rebuild and I've considered suggesting he demo the last 2 bays and creating a new end wall on the remaining building. Does anyone see any issues with this if the lateral x-bracing is not in the last 2 bays? The building is not very tall. I would construct a new grade beam and have studs span the end wall from slab to end frame (previous interior frame).

 

[msquared48]

Seems to me that if the new end bay locatolion is a mainframe and no sidewall x bracing is to be elimated, there should be no problem.

Mike McCann, PE, SE (WA)

 

[racookpe1978]

Be careful of the mechanical details of the new structural connections to the old vertical members. You may need some local reinforcement to avoid pulling out or deformation of the new connections where penetrate into the old verticals. The PEMB industry is notorious for choosing "just enough" holes and screws and web/flange thicknesses to avoid collapse.

 

[msquared48]

If the new end wall is a mainframe, you will not need any X bracing in the new end wall structure.

In fact, the new end wall should be twice the lateral capacity needed...

Mike McCann, PE, SE (WA)

 

[msquared48]

May have to re-configure any X bracing in the roof diaphragm structure though...

Mike McCann, PE, SE (WA)

 

[ajh1]

Caution if you are in an area with snow loads or high wind loads. Assuming the purlins are continuous, the old interior bay purlins with continuity at both ends may not check for what will now be your new end bay. They will now be continuous on one end and pinned at the other which is a more severe loading scenario.

 

[JedClampett]

What I've seen is that the PEMB manufacturers "double up" (nest) the purlins over the interior supports. It's going to be a challenge to pull the purlin of the removed bay out. As ajh1 said, you'll have to check the first purlin (and for that matter, the girts) for this effect.
Also, you're now going to have edge (zone 2 and 3 for the roof, Zone 5 for the wall) wind loads. If the building even complied with its design wind loads, the new ones are likely higher and applied in different ways.
This is not a slam dunk engineering undertaking. You're taking full ownership and liability for this building design. Don't underestimate the surprises and difficulty of it. You might have to measure the frames, purlins and girts to the gage thickness level. These building are designed to the gnat's butt if you're lucky.