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Re: Base Plate design

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Just be careful in your design. Some authorities insist on using a rigid plate method to design baseplates, others insist on using a flexible plate approach. And each authority will claim the other is wrong. There is also disagreement on how to do the flexible plate method, so you shouldn't believe the first one you come across, which for structural steel is usually the prying action discussion in the steel manual. (I am definitely uncomfortable with using that method in certain situations, but that's my opinion.)

Having done both, the flexible plate method is more conservative but requires a lot more effort; and at times, results from the rigid plate method was actually unconservative when compared to experimental evidence.

I don't recall which method Blodgett recommends as I haven't used it in a long time, but when I was using it I found it to be unconservative also.

So do it with care and good judgment.


----Original Message Follows----
From: Andy Heigley <aheigley(--nospam--at)jgaeng.com>
Reply-To: <seaint(--nospam--at)seaint.org>
To: seaint(--nospam--at)seaint.org
Subject: Re: Base Plate design
Date: Thu, 28 Feb 2008 09:49:30 -0500







I have the Blodgett book and the AISC Design
guide.  Both references do not discuss a column base subjected to
Moment with uplift forces.  (When i say uplift, i mean that the axial
force on the column is tension, or Pu = -60 K)



For instance, if my uplift is large in combination with a smaller
moment, there may not be any compression force on the baseplate.  All
bolts will be in tension, but one side of the anchor rods will be in
higher tension loads than the other due to the moment.



Now, what if you have a large uplift, and a large moment, where you
have a little compression on the baseplate, etc. 



With these conditions, i don't think that the the expression for 'Y'
(the length of plate in compression) is applicable.



I hope you can understand my question.  if you need an example, how
would you design a baseplate for Pu= -60K with Mu = 130 k-ft?



Thanks for your responses...





Andy Heigley, PE






Micayas, Julius wrote:
















Andy,

 

I got one
good reference for you from AISC
titled: Steel Design Guide Series
1

 

Column
Base Plate

By: John T.
DeWolf

 

Some
Practical Aspects of Column Base Selection

David T.
Ricker

 

This is a
publication combined issue by the
AISC and the Berlin Steel Company, Inc.

 


Engr. Julius
Micayas

P.E. license
no.32969

Project
Manager/Sr Lead
Structural engineer

River
Consulting LLC

111
Veterans Memorial Boulevard

               Suite 1600

Metairie,
  Louisiana
  70005

Phone -
504-841-3014
(direct)

504 837-5275
(office)

Fax -
504-837-2986

E-mail: jmicayas(--nospam--at)riverconsulting.com

W-page:           
  www.riverconsulting.com





From: Gary
Loomis [mailto:gloomis(--nospam--at)MasterEngineersinc.com]

  Sent: Thursday,
February 28, 2008
7:46 AM

  To: seaint(--nospam--at)seaint.org

  Subject: RE: Base
Plate design


 

Yes,
Blodgett ?Design of Welded
Structures?  is probably one of the best.  And it is relatively
cheap $10.00.

 


Gary W. Loomis, P.E.,
Senior Structural Engineering

Master Engineers and
Designers, Inc.


-----Original
Message-----

  From: Andy Heigley
[mailto:aheigley(--nospam--at)jgaeng.com]

  Sent: Thursday,
February 28, 2008
8:30 AM

  To: SEAINT

  Subject: Base Plate
design

 

Hello all:



I'm looking for any references for designing column base plates where
the
column base is subjected to uplift and a large moment.



The AISC design guide does not discuss a column base with moment in
combination
with uplift.



Does anybody have any references for such a design?



Thanks in advance,







--

Andry Heigley, PE

 

 

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