How to eliminate tension springs in SAP2000

[hossein mardanlo]

Hi,

 

In SAP2000 software in assigning area spring to shell elements, there are available both "tension-compression" and "compression-only" springs, But even if "compression-only" is selected, in output results, tension is developed in springs. I don't know how we can model and analyze compression only springs to exactly model the soil-foundation contact situation.

 

Regards,
Hossein Mardanlo

[Fugeeo]

Remember the Alamo - Y2K

--------- Original Message --------
From: sea...@seaint.org
To: ETAB...@yahoogroups.com <ETAB...@yahoogroups.com>, sea...@seaint.org
<sea...@seaint.org>
Subject: How to eliminate tension springs in SAP2000
Date: 11/28/09 17:20

> Hi,
> &nbsp;

> &nbsp;
> Regards,Hossein
> Mardanlo

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[Daryl Richardson]

Hossein,

 

        One crude way that you can rely on (if you can not find a better way) is to analyze it with normal springs then delete (or make inactive) all of the springs in tension and reanalyze it without those elements acting.

 

Regards,

 

H. Daryl Richardson

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

From: hossein mardanlo

To: ETAB...@yahoogroups.com ; sea...@seaint.org

Sent: Saturday, November 28, 2009 1:16 PM

Subject: How to eliminate tension springs in SAP2000

[Milo Zabala]

Try calling their tech service, they should be able to resolve those issues, or may show some kind of "go-arround" tricks to get a similar result. 

--

Thanks,

Milo Zabala 

[Conrad Harrison]

Hossein,

 

May be the problem is with the dimension. If it was a simple block with an eccentric load and designing manually, and too little of the base was in compression, then would change the size of the block.

 

As far as I understand software with tension-only and compression-only elements calculates tension and compression in the elements irrespective of the type. It just, sets the values to zero and keeps iterating if the value is opposite to the type. If the software has good error trapping, it will advise no solution can be found, otherwise it will simply fail to converge on a solution and reach its iteration time-out limits, and leave the solution matrix with a not so valid solution.

 

Since cannot have tension (unless providing some form of anchor/hold-down)  then has Daryl suggested need to remove those  springs. If that is a lot of springs then maybe the design footprint attempting to assess has a problem.

 

 

Regards

Conrad Harrison

B.Tech (mfg & mech), MIIE, gradTIEAust

mailto:sch.te...@bigpond.com

Adelaide

South Australia