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Re: Concrete Spring Constant for Base Plate Modeling

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Concrete has a nonlinear compressive stress-strain curve after around 0.5*f'c and after then a linear spring would not be an accurate assumption.
 
Will H
 

 
On Fri, Jan 30, 2009 at 1:42 PM, David Fisher <dfisher(--nospam--at)fpse.com> wrote:

 

Hooke's Law is bascially F = k*x

 

F, I assume you know.

 

x = say 0.1" just to pick a value, solve for "K" which is your spring constant.

 

Not sure what your structure/foundation type is or load magnitudes…

 

That's a good place to start, if the results don't make sense, then reduce the value of "x" as necessary

To make the results reasonable.

 

The bigger question might be, why are you modelling this condition this way?

AISC has spent years developing the base plate design criteria.

 

Can't you just use that design procedure?

 

 


From: john yang [mailto:jeongidea(--nospam--at)gmail.com]
Sent: Friday, January 30, 2009 12:38 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Concrete Spring Constant for Base Plate Modeling

 

How can I assume "the extension"?  For spring, k=EA/L I know E and I know A and I know concrete compressive strain (0.003).  The problem is L or deltaL.  How can I assume those?  Will L be full length or depth of member? How much will I assume delta L for it?

Thank you so much.

John

On Fri, Jan 30, 2009 at 9:31 AM, David Fisher <dfisher(--nospam--at)fpse.com> wrote:

Try my favorite formula, the foundation for structural engineering:

 

Hooke's Law:

 

"as the extension, so the force…"

 

 

 

 

David L. Fisher SE PE

 

Fisher and Partners - Cayman

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75 Fort Street Georgetown Grand Cayman BWI

319 A Street Boston 02210

 

312.573.1701

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www.fpse.com

 


From: john yang [mailto:jeongidea(--nospam--at)gmail.com]
Sent: Friday, January 30, 2009 11:29 AM
To: seaint(--nospam--at)seaint.org
Subject: Concrete Spring Constant for Base Plate Modeling

 

Hi,
I am modeling base plate on the 6000 psi concrete column and I want to put concrete compression only spring to represent concrete.  The problem is what is the compressive spring constant of concrete.  Could you help me to get it?

Thank you so much.

John