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RE: Column Base of Industrial Building

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The design of industrial buildings should be primarily governed by
serviceability. We have become accustomed to seeing pre-engineered one-story
buildings in all of the new industrial complexes. These facilities function
well as shelter; however if the building is subjected to industrial loading,
ie..cranes, conveyors, or vibratory equipment, the building has a
significant service requirement.
These requirements are not normally defined and have been left to the
engineer with only a few guidelines. AISE publishes a Technical Report # 13
which covers the design requirements for heavy industrial buildings (steel
making facilities). It is very useful in evaluating Class D,E & F Crane
buildings.  Lateral drift is limited to L/400 at the top of crane girders.
TR # 13 also recommends a design criteria developed by the geotechnical
engineer for spread footings such as:
1. Allowable soil bearing pressure.
2. Earth pressure and safety factor for lateral and rotational stability.
3. Estimated total and differential elevations for various sizes of
foundations at different elevations and coefficients for calculation of
lateral movements.
4. Ground water conditions.
5. Minimum depth for frost protection.
6. Description and effect on foundation of overlapping soil pressures caused
by existing and proposed structures, process and machinery foundations,
floor loads, walls, basement surcharges, excavations, vibratory equipment,
etc.

There is a similar recommendations for Pile and Caisson Supported
Foundations.

The answer to the question, fixed or pinned, is an engineers decision. Good
Luck

David I. Ruby, S.E.
Chair, Coalition of American Structural Engineers
President, Ruby & Associates, P.C.
30445 Northwestern Hwy., Suite 310
Farmington Hills, MI 48334-3102

Phone:            (248) 865-8855
Fax:              (248) 865-9449
Cellular:         (248) 514-2677
E-mail:           druby(--nospam--at)rubyusa.com

-----Original Message-----
From: Paul Ransom [mailto:ad026(--nospam--at)hwcn.org]
Sent: Friday, November 17, 2000 12:38 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Column Base of Industrial Building


> From: "Calvin Chang" <ccpe(--nospam--at)ms38.hinet.net>

> When designing a one-story sloped-roof industrial building with span =
> 100'~200', there are two choice for the column base, i.e., fixed and =
> pinned.
>
> 1. considering only wind load, which is better, or both are acceptable?
> 2. considering seismic load, which is better, or both are acceptable?
> 3. if there is a crane with crane girder bracket welded at the column, =
> which is better, or both are acceptable?
>
> Your opinions are highly appreciated.
>
> Thanks,
>
> Calvin Chang
>
> >> What is the height of the building?

> span: 100'~200'
> main frame spacing: 20'~40'
> eave height: 30'~60'
> roof slope: 10(horizontal) : 1~2(vertical)

Base fixity decisions will be based on cost distributions and service
conditions (e.g. acceptable deflections vs cost for more steel vs cost
for more foundation) more than loads. Local variations in costs for
material and labour can be significant.

Generally, buildings with crane beams mounted on a column bracket can be
easily deisgned with a pinned base. Heavier cranes will have substantial
foundations so that a fixed base is a much smaller incremental cost
issue.

The engineer's job is to determine what economically meets his client's
requirements within all regulatory conditions.

Note: be sure that the base is actually detailed to respond
appropriately to the fixed or pinned design assumptions.

--
Paul Ransom, P. Eng.
Civil/Structural/Project/International
Burlington, Ontario, Canada
<mailto:ad026(--nospam--at)hwcn.org> <http://www.hwcn.org/~ad026/civil.html>