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Active Member
eiriknor
Posts: 9
Registered: ‎03-14-2011

Plate and shell reinforcement type

397 Views, 4 Replies
11-02-2012 06:26 AM

I have some pre-fab slabs that shall be the deck in a parking garage. On top of these slab there shall be 100 mm cast-in-concrete. The slabs should transfer live loads to the columns, but also wind loads from the columns through the deck and into the walls that support the whole structure.

 

Doing a reinforcement calculation with "bending + compression/tension" get a bit messy reinforcement map. Ì wonder if I can do one calculation with this "simple bending"-option and reinforce the slabs with this and the cast-in-concrete (if I get some reinforcement in the upper layer).

 

Then do a re-calculation with "compression/tension"-option and put all of this reinforcement in the cast-in-concrete part.

 

I`ve tried this, and I sure get a much more "clean" reinforcement-map in both cases. But I`m afraid I`m missing something here and my structure will collapse when it starts to blow.

 

Hope someone can help me out with this one.

 

Construction.JPG

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Product Support
Artur.Kosakowski
Posts: 5,111
Registered: ‎12-17-2010

Re: Plate and shell reinforcement type

11-05-2012 12:19 AM in reply to: eiriknor

I think you need to answer yourself a following question - are the in-plane forces (tension / compression) small enough to be ignored for reinforcement calculations? If yes, then you can select the simple bending mode, otherwise you probably should select tension/compression + bending instead. You may also try to switch off calculations of minimal reinforcement to check how the reinforcement distribution would looks like. This should give you a better understanding of the situation when the tension force causes the need for minimal reinforcement in the slab.

 

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

 

 



Artur Kosakowski
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Active Member
eiriknor
Posts: 9
Registered: ‎03-14-2011

Re: Plate and shell reinforcement type

11-05-2012 02:42 AM in reply to: Artur.Kosakowski

The tension/compression forces are not samll enough to be ignored, that I know for sure. The "simple bending - compression/tension" option gives me no control of how much of the reinforcement is caused by the membrane forces. Since I have these pre-fab slabs I`m not able to have continous reinforcement in the lower part of the deck, only in the "cast-in"-part. I`ve done a couple of calculations and it seems for me that in my case regarding the reinforcement that "simple bending - compression/tension" "=" "simple bending" + "compression/tension".

 

Eirik

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Active Member
Ch.Charitidis
Posts: 10
Registered: ‎10-03-2013

Re: Plate and shell reinforcement type

10-24-2013 01:33 AM in reply to: eiriknor

Hi,

 

I have been having a similar issue and I am wondering if my reasoning, although quite simplistic, has any merit.

If the design is performed once against tension/compression and once with simple bending and we add the reinforcement quantities, shouldn't that reinforcement be then equal to the reinforcement provided if designing with bending +compression/tension?

I have tried this but the bending+compression tension produces more reinforcement than the sum of the two separate designs combined. Any idea why that is happening?

 

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Product Support
Artur.Kosakowski
Posts: 5,111
Registered: ‎12-17-2010

Re: Plate and shell reinforcement type

10-24-2013 01:48 AM in reply to: Ch.Charitidis

Bending + tension/compression

 

case1: bending + small tension :

top under compression (no reinforcement)

bottom: tension + tension -> large reinforcement

 

case 2: small compression - no reinforcement

 

case 3 small tension

 top and bottom small reinforcement

 

Final reinforcement:  

top: small reinforcement

Bottom: large reinforcement

 

 

-------

 

Bending:

 

case1: bending :

top under compression (no reinforcement)

bottom: tension ->  smaller than large reinforcement)

 

Tension/compression

 

case 2: small compression - no reinforcement

 

 case 3 small tension

 top and bottom small reinforcement

 

Final reinforcement:

top: small reinforcement

bottom: smaller than large reinforcement

 



Artur Kosakowski
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