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# RE: Concrete Spring Constant for Base Plate Modeling

• To: seaint(--nospam--at)seaint.org
• Subject: RE: Concrete Spring Constant for Base Plate Modeling
• From: <jwhite(--nospam--at)megr.com>
• Date: Sat, 31 Jan 2009 01:33:33 -0300

```Wesley, that was a great link.  How can I get more like that?

- Jeremy

Quoting Wesley Werner <wwerner(--nospam--at)conewago.com>:

> John,
>
> few slides into the presentation the presenter talks about spring
> constants. He concludes that for 3,000 psi concrete the value is about
> 1,000,000 lb/in. For 3,000 psi grout the value would be 2,000,000 psi.
>
>
> Wesley C. Werner
>
>
>
>
> ________________________________
>
> From: john yang [mailto:jeongidea(--nospam--at)gmail.com]
> Sent: Friday, January 30, 2009 2:22 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: Concrete Spring Constant for Base Plate Modeling
>
>
> Hmm,  just pick the number. However, the question is what is the
> reasonable number.
>
> Depending on spring constant,  it will change tensions on the anchor
> bolts.  If somebody starts with no idea of bolts' tensions,  they may
> come up with very small number if they use very flexible springs.
>
> Anyway,  the reason that I am modeling the base plate instead of using
> AISC design guide is my base plate has re-entrant corner inside and have
> both direction lateral loads (of course both direction shears and
> moments) at the same time.
>
> I want to know how much stress concentrations at the re-entrant corners
> are and I don't think AISC design guide covers this situation.
>
> Thank you so much.
>
> John
>
>
> On Fri, Jan 30, 2009 at 10:42 AM, 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.
>
>
>
> 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
>
> 	372 West Ontario Chicago 60610
>
> 	75 Fort Street Georgetown Grand Cayman BWI
>
> 	319 A Street Boston 02210
>
>
>
> 	312.573.1701
>
> 	312.573.1726 facsimile
>
> 	312.622.0409 mobile
>
>
>
> 	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
>
>
>
>
>

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