×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Stiffness of Base Plate on Perimeter Wall

Stiffness of Base Plate on Perimeter Wall

Stiffness of Base Plate on Perimeter Wall

(OP)
I am trying to figure out the stiffness of a base plate for a steel column resting on a perimeter foundations wall.  I am running through the procedure in the PCI Design Hand Book (section 3.8.2).  Using the PCI I can easily calculate the flexibility of the base plate and the anchor bolts but I’m not sure how to account for the flexibility of the foundation wall/footing.

The PCI does give an equation for the flexibility of the foundation but that is for an isolated footing only.
 

RE: Stiffness of Base Plate on Perimeter Wall

Flexibility is the inverse of stiffness, EI is the stiffness.  The foundation wall will have much greater stiffness, (order of magnitude greater).

RE: Stiffness of Base Plate on Perimeter Wall

(OP)
I understand that flexibility is the inverse of stiffness.  In the PCI they have an equation for the flexibility of the footing = 1/(soil modulus * moment of inertia of footing)esentially 1/EI.  This is for an isolated footing.  For a column that is going to be on a foundation wall would you assume then that the foundation is infinitely rigid because the moment of inertia for the wall footing would be incredibly large?

RE: Stiffness of Base Plate on Perimeter Wall

If you are talking about a long stemwall, 8" to 10" thick, four to 8 feet high...most definitely assume infinitely rigid.  

However, if you are talking about a short 6" thick stemwall, one foot or less high, over a thin strip footing, I would look to the spread footing comparison.

Anything in between, assume something between a spread footing and infinity.  That close enough for you? bigsmile

Mike McCann
MMC Engineering

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources