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RE: base plate software

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Could either a steel fabricator or someone from AISC respond regarding
economical base plate thicknesses? At what point does it become more
economical to start using stiff. plates or other stiffening elements to
reduce the base plate thickness. An example is using stiff. plates or small
channels at moment frame or braced frame columns with large uplift loads.
There would be a savings in material. However, there is added shop welding
of the stiffening elements.

thanks in advance,

-----Original Message-----
From: Keith Fix [mailto:kefix(--nospam--at)]
Sent: Tuesday, June 13, 2000 11:01 AM
To: seaint(--nospam--at)
Subject: RE: base plate software

I have base plates on a project with t > 2", due to bending moments.  Plate
thickness is governed mostly by distance of edge of plate to column edge.

Are base plate stiffeners warranted due to assumption of uniform stress
base plate?

Keith Fix
Cromwell Architects Engineers

--- "Khosrownia, Ghassem SPK" <GKhosrownia(--nospam--at)> wrote:
> Yes: be aware of the software that advertise finite element analysis of
> steel base plates complete with nice looking color coded stress
> distribution. All of this is fine, but to me it indicates that the
> developers may have no idea what an engineer needs to perform practical
> work. And that might result in other shortfalls down the road. We should
> never need to analyze the heck out of a base plate. We should never
> bending moment from a steel column to foundation via flexible steel base
> plate. If moment transfer is required the best way is to transfer directly
> through the flanges of the column via anchor bolts. Base plates should be
> designed for vertical loads only. We have enough to worry about without
> having to consider the flexibility of a base plate in the load path. At
> least this is what my practice is. Design of base plates starts from using
> 3/4" steel plate (for various reasons not necessarily related to load),
> should be checked for stresses using the two or three simple AISC
> formulas. Stay away from using 2" plates (or thicker) if you have any
> at all. Use thick plates with caution. They require special milling and
> welding procedures. Try to stay within 1" to 1 1/2" plates if at all
> possible.
> Ghassem.

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