Sunday, November 8, 2009

Re: base plate design

Highly neglected topic. No good single reference. The problem is the huge
range of possibilities that can occur in: member section (shape and aspect
ratios); load effects at the theoretical section end; local effects in the
column, plate, rods, grout, concrete, welds; geometry of rod pattern; base
shear (a topic in itself); elastic/plastic transition; flexible/rigid;

There was an interesting presentation at NASCC '09 in Phoenix, Better Base
Plate Designs. I'll follow up if I can remember the researchers involved. I
had a chat with them before I attended because I didn't want to waste my
time. They reinforced the need for rigorous analysis. I believe that the
work was supported by RISA Technologies for RISABase.

I probably spend as much time with base plates as with the most complex
connections in a structure. Lots of iteration and no single controlling
case. I like to bracket my solutions to determine how much time to spend. If
the best case and worst case are both within an order of magnitude, just go
high. Quick method, to borrow a phrase from a colleague, "... round up and
double ..."

I'll repeat a question that I asked a while back:
Has anybody ever known a structure failure due to base (steel/concrete) or
anchor failure in the finished state (not during construction)?
I have heard anecdotal stories but nothing confirmed as engineering failure
vs overload, material or construction failures.

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

> From: "John J. Treff" <>

> Does anyone have an example or a good reference for biaxial base plate desi=
> gn? AISC Design Guide 1 deals only with uniaxial bending. Any references (=
> books=2C manuals=2C papers=2C etc.)=2C suggestions or ideas on how to desig=
> n biaxially (interaction of some sort or design separately for both axes an=
> d then pick the worst case scenario) would be greatly appreciated.

> From: "Adair, Joel" <>

> Not that this will provide you with any guidance or understanding, but
> RISA makes RISABase, which will handle biaxial bending, and just about
> any other load combination you can dream up. We had it when I worked

> -- Joel Adair

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