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Re: Structural Engr. as A Prime

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> From: "Jie Lu, P.E., S.E." <jayjielu(--nospam--at)>
> To: <seaint(--nospam--at)>
> Subject: Structural Engr. as A Prime 
> Fellow Engineers:
> I have a project of 45,000 S.F. pre-engineering building with
> seven (7) small cranes.
> The owner would like to have structural engineer to serve
> as the Prime to form a design team.
> CASE document #13 could serve my need.
> However, I would like to have your comments as to what should I watch for.
> Thank you in advance.
> Jie Lu, P.E., S.E.
> J. Lu International, LLC

Are you looking for suggestions regarding the structural aspects of a
pre-eng, multi-crane building, the contractual aspects of being a
multi-discipline design leader or the engineering apsects in a
mutli-discipline project? Or all of the above?

Do you design pre-eng buildings or will you be the specifying engineer?
Pre-eng is typically designed with minimal extra capacity and higher
than typical deflection allowances. Ensure that all trades identify
specific loads, deflection limitations and operating conditions
(especially the cranes) and consult with the pre-eng designer - the MBMA
Low Rise Building Systems Manual will probably be used as a design

CRANES can cause you some big headaches. Ensure that you have all crane
clearances (under hook, top of steel, and top of steel to u/s of
rafter). If possible, identify the specific crane equipment that will be
used or use adequately conservative clearances. Otherwise ensure that
YOU are prepared to deal with the consequences of inadequate clearances.

Note: top of steel will mean different things to different suppliers
(top of crane support, top of crane beam, top of rail)

Leave bays, parallel to crane travel, for bracing. It is amazing how
many times this is forgotten.

Make sure that it is clear as to who provides runway beams, brackets,
rails, braces, stops and all connecting hardware.

Ensure that all trades are aware that they CANNOT connect ANYTHING to
the FLANGES of cold formed members (purlins and girts). Do NOT accept
simple area loadings for things such as water pipes and cable trays that
will be suspended by point connections - area loads are probably
adequate for frames but rarely for cold formed members supporting point
loads. Get service routings early (dream on).

Envelope penetrations: doors, windows, vents, fans, chimneys. Who, what,
where, what size, weight, roof mounted, flashings, curbs, framing
requirements with nominal dimensions. All these are more critical in the
pre-eng business.

That's the building. Then there's everything below ground, on the
ground, outside the building and inside the building ... There's a book
to be written, I think.

Are there architects or any other consultants involved?

Paul Ransom, P. Eng.
Burlington, Ontario, Canada
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