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RE: Metal Building Notes and Other Gripes

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Sounds like the light pole manufactures provide a minimum embedment that we
don't.  Does that really help out the foundation designer to a great extent?
If it does then repeatedly ask for it...  if enough people want it we will
provide it.  

But what if the designer wants a different type of anchor bolt due to
geometry restrictions and a lesser embedment is required than what we might
specify?  Should the designer be tied to providing only what we specify?
What if the footing ties into the slab?  Should we then design the slab,
retaining wall and all other pieces connected in some indirect way to the
building?  Should we design the sprinkler systems on the lot so that we can
control the moisture content of the clays around the footings to avoid
differential settlement?  Somewhere a reasonable line must be drawn.  The
HVAC designers don't design the joists which support their equipment and the
frames which support those joist and the footings which support those
frames...  Why not? aren't all of those things required to support their
equipment?  Doesn't that leave them with no proof that their design is
adequate or achievable?  They don't just hang in the air...  Why is this the
expected procedure for HVAC and "completely inappropriate" for PEMB?

Enough rhetorical questions, here are some facts:

1) PEMB manufacturers ARE responsible for determining the diameter and
placement of the anchor bolts.  Typically A307/A36 material is assumed for
the anchor bolts.  
2) Embedment length, concrete mix (strength, slump, etc.), tie requirements,
etc. are not determined by the PEMB manufacturers and the chosen design
requirements may not even be known by us.  
3) All of the required information to design the frames and base plates is
known by the PEMB manufacturer.  (Reactions, Bolt diameters, bolt patterns,
base plate dimensions, welds to columns, etc.).
4) Your comments regarding pre or post installed anchors are correct.  We
MUST know if they are pre or post installed.  For the case of post installed
anchors (which is the exception for us) the uplift cones and anchor
manufacturer recommendations and/or design procedures are used for
determining adequacy of the anchor.  For post installed anchors you still
need to make sure that the concrete slab/footing can handle the loads from
the anchors...  Again we have no reasonable way to check the adequacy of
that.  As far as the base plates, they don't care if the anchors are post or
pre installed.

With all of this in mind, giving the designer: 1) the size of the anchor
bolt, 2) minimum material properties for the anchor bolts, and 3) the
reactions, this seems like a fairly solvable problem (designing the anchor
bolt embedment and footing sizes) yet this approach also offers a lot of
flexibility for the footing "expert" to come up with an efficient design.

Do you really want someone who has no knowledge of the concrete mix being
used, slab layout desired, quality of soil on the local jobsite (more
detailed than what is required for seismic calculations) to determine the
anchor bolt embedment and foundation configurations?

Greg Effland, P.E.

-----Original Message-----
From: Paul Feather [mailto:pfeather(--nospam--at)]
Sent: Wednesday, November 27, 2002 10:43 AM
To: seaint(--nospam--at)
Subject: Re: Metal Building Notes and Other Gripes

I have been reading this thread with interest.  I typically will not get
involved in Metal Building Projects, so my comments are form the "outside"
so to speak, and not from any direct experience.

The single item that strikes me in the positions / communications from the
metal building manufacturers is the point that you do not design and are not
responsible for the anchor bolts that attach your buildings to the provided
foundations.  This in my opinion is completely inappropriate.  If you do not
design the anchor bolts, how do you design the base plates?  How can you
separate yourself from the realities of whether or not the anchor bolts are
pre or post installed?  If the end product is going to require
post-installed anchors, the anchor bolt layout and the base plate need to be
compatible with the capacities of post-installed systems, with all the
spacing and embed requirements considered.  How do you know if your design
requirements are even achievable?

It is one thing to provide an anchor bolt requirement with delineated force
requirements to another engineer to enable the appropriate design of the
foundation system.  It is quite another to design in a bubble and absolve
yourself of any responsibility for how your structure is attached.  Even
light pole manufacturers provide specific base plate and anchor bolt
requirements, including size and embedment.

Just my opinion.

Paul Feather PE, SE

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