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Ivana1607
Posts: 4
Registered: ‎02-06-2013
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Hollow core slabs and seismic

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02-13-2013 08:12 AM

Hi,

can anyone tell me is it possible to do modal analysis and seismic calculation with hollow slabs in construction model?

Thank you very much.

Ivana

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Rafal.Gaweda
Posts: 5,048
Registered: ‎04-26-2010

Re: Hollow core slabs and seismic

02-13-2013 08:29 AM in reply to: Ivana1607

Yes, it can be calculated.

 

hs.jpg

 

 



Rafal Gaweda
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Ivana1607
Posts: 4
Registered: ‎02-06-2013

Re: Hollow core slabs and seismic

02-13-2013 11:41 AM in reply to: Ivana1607

Thank you for your answer. I've already defined hollow slab in my model but during analysis error 902 appears. After that I changed the slab into homogeneous (just for check) and no errors showed, calculation was fine. I thought maybe self weight of hollow slab is not converted to masses?!

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Rafal.Gaweda
Posts: 5,048
Registered: ‎04-26-2010

Re: Hollow core slabs and seismic

02-14-2013 01:25 AM in reply to: Ivana1607

Error description : 

 

http://docs.autodesk.com/RSA/2013/ENU/index.html?url=filesROBOT/GUID-8E8ED7A4-9A55-4F1F-8771-7E1A9CE...

 

902

Negative eigenvalue has been obtained

 

PLease send me model to check



Rafal Gaweda
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Member
Ivana1607
Posts: 4
Registered: ‎02-06-2013

Re: Hollow core slabs and seismic

02-14-2013 06:15 AM in reply to: Rafal.Gaweda

Here is the model. (Original model is too big to send so I made a little example)

Thank you.

Ivana

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Rafal.Gaweda
Posts: 5,048
Registered: ‎04-26-2010

Re: Hollow core slabs and seismic

02-14-2013 06:39 AM in reply to: Ivana1607

Ivana,

 

Take a look below. You have defined wrong geometrical properoes of holes in holow slab.

Opening bottom edge is 2mm below slab bottom layer

ho/2 = 160 and hc=158 -> ho must be less or eq to 316

 

ho.jpg

 



Rafal Gaweda
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Rafal.Gaweda
Posts: 5,048
Registered: ‎04-26-2010

Re: Hollow core slabs and seismic

02-14-2013 06:46 AM in reply to: Rafal.Gaweda

To help you checking : matrix values can not be negative 

 

matrix.jpg



Rafal Gaweda
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Member
Ivana1607
Posts: 4
Registered: ‎02-06-2013

Re: Hollow core slabs and seismic

02-14-2013 06:53 AM in reply to: Rafal.Gaweda

Yes, that was the problem. Thank you very much!!

Ivana

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