Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Pre-$%!#&#& metal buildings

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Comments interjected, below.

> From: "Andrew Kester, P.E." <akester(--nospam--at)>

> Sorry, this is a major long PEMB rant. My bad. But this is my therapy. =
> And the "P" should be for post-engineered, because the engineering =
> involved seems to leave something to be desired.

We get so used to referring to the PEMB industry as if it were one large
coagulated group that could change practices in some united way. Reality is
that the PEMB industry is made up of a LOT of individual companies with
wildly diverse technical abilities and business practices selling a broad
range of structures through different marketing channels.

There's a good chance that there is nobody in the procurement chain that is
technically savvy, let alone that they might care about any notes on your
drawings or recognize that they should pass them to the PEMB manufacturer. I
think that your project hit the rocks on this point.

The manufacturer will quote the building supply based on their standard
practices and details UNLESS it is explicitly requested in the quote
request. Additionally, many manufacturers do not encourage coordination via
review feedback - the drawings are issued, the steel is on the way.

It comes down to the way in which the owner decides to purchase the building
and the basis of that decision. Lowest cost will give the most coordination
headaches for somebody.

> So we find ourselves on the crappy end of lots of PEMB projects, not =
> that there is a good end, and not that I have a problem with PEMB in =
> general, but being the EOR is getting to be quite the hassle for not =
> thanks and not enough money. I would like to hear some other gripes =

Set your fees to make money or lose the job. You will sleep better.

> design process. We are suddenly asked, err, required, to supply =
> preliminary design for permit and bid before they select a PEMB mfr. I =


> set but anyway.... I tell the architect, a good client, we traditionally =
> require at least preliminary building dwgs and calcs in order to size =
> our footings, otherwise it does not make sense really and we are not =

> I run a few quick moment frames and get the foundations within reason =
> (and we ended up being doggone close when compared to the PEMB final =
> calcs). Though the GC is threatening to come back to us with a change =

It's not hard to achieve close results. I normally suggest that the
foundations be designed for 10% more gravity/uplift and 25% more horizontal
than provided in preliminary reactions.

> Our notes also HIGHLY RECCOMEND a min 8" bolt spacing. Well I think we =
> will require a 6" min. at least in the future. They come back with 1" =
> diam bolts at 4" o.c. because that neatly fits inside their base plates =
> and probably minimizes steel design, but dangit Vern you can hardly keep =
> the washers from hitting each other when they are that close together? =
> Doesn't anything seem counterintuitive to place big ole boy bolts that =
> close?? Then again, I gather from phone conversations the PEMB =
> "designers" are great with the PEMB software and probably not engineers. =

The "designers" tend to be very conscientious and knowledgeable engineers
(exceptions exist). However, they are "designers" of a manufactured product
and make design choices based on the manufacturer's preferred practices.
Some companies will not accept consultant drawings or specifications with
the building order to force the buyer to explicitly define the requirements
of the product without the manufacturer trying to interpret submissions in
various states of completion and coordination. It's not wrong, it's just

> We mark up all of their base plates after running calcs on every =
> scenario on their shop dwgs (with a 2 day turn around I might add), and =
> end up with very reasonable 5"-8" bolt spacings. We get no fewer than 5 =
> phone calls over the next couple of days asking are you sure? Really? =
> Why? It works for us, why not you? We always do it this way. No other =

Aside from the fact that these responses were very knee-jerk, and you don't
specify whose knee was jerking, the manufacturer needs to establish that
they are not wrong, for exactly the reasons that you cite, below. Recognize
that it is possible that neither of you were wrong.

A good company will learn from this mis-coordination. Another company won't
care because you influence a minor portion of their business.

I'm a little curious about the 8" rod spacing requirement. I assume that you
require min 8" in each orthogonal direction. What is the controlling design

Most manufacturers will increase spacing with bolt diameter.

> We have also had PEMB jobs run smooth as silk, with second story =
> mezzanines and other tricky elements.=20

Look at the manufacturers and the contractors involved. If the GC is a
trained, conscientious dealer for a major manufacturer, they will work like
hand in glove.

> I guess make mandatory requirements like the GC shall supply a full set =
> of our drawings to the PEMB mfr for review and coordination, and put a =
> minimum spacing that WE REQUIRE. But what else can we do? I read some =

It probably won't work. Somebody will convince the owner that you are being
overly cautious and, besides, it will cost more. Manufacturer liability
issues aside.

> Am I ignorant to assume someone is reading our drawings besides me, =
> until it is way too late??....  :-----(

You said it up front: How do you final design foundations without building
reactions? You need to educate your friend the architect to get those
coordination issues in the building supplier's contract ESPECIALLY for
complex projects (contractual relationship assumptions made here).

I recently commented, in another SEAINT thread, on an issue about PEMB base
details and the design basis for their rod size and pattern recommendations.
The manufacturer does not design anything below the base plate. So, the rod
qty., dia. and placement are reflections of their design results but may not
be sufficient for the foundation.

> Andrew Kester, P.E.

Paul Ransom, P.Eng.
ph 905 639-9628
cell 905 802-3707
fax 905 639-3866

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at:
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*   Questions to seaint-ad(--nospam--at) Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: 
******* ****** ****** ****** ******* ****** ****** ********