Minimum reinforcement for Post-tensioned Transfer Plate 2

[KAR FUNG]

Hi all,

May I know, what is the minimum reinforcement for post-tensioned transfer plate? From which code/standard ?

Thanks.

 

[rapt]

The same as for any other post-tensioned slab! No code that I know of provides special rules for transfer plates.

You need to provide sufficient reinforcement to handle ultimate strength, crack control for service and transfer conditions and for all of the intermediate loading and construction stages.

 

[KAR FUNG]

Hi Rapt,

Thanks for your reply. For your information, I have received some info from consultant that refer to British TR43, minimum reinforcement required is 0.075% per section. But, I disagree with the statement. Cause 0.075% is less than the minimum reinforcement 0.13%.

 

[Retrograde]

TR43 requires a minimum of 0.075% of normal reinforcement (in addition to any PT) in the top of the slab over column locations to distribute cracking.

I am not sure where your 0.13% comes from.

 

[KAR FUNG]

0.13% is from BS 8110. We plan to design PT transfer plate for 30 storey building. Minimum reinforcement can be 0.075% ?

 

[rapt]

Kar Fung.

Read the code.

.0013 is for reinforced concrete! And it is wrong anyway for normal concrete strengths used these days.

TR43 says the minimum top reinforcement for PT slabs is as you stated, and it "includes" any boneded PT in that area, it is not in addition unless the PT is unbonded.

But that is not specific to transfer slabs, it is for any slab. You asked for specific rules for transfer slabs. And that was my answer above.

 

[Retrograde]

 

[rapt]

Retrograde,

Have you read the Addendum released a year or so later that clarified a few sections, including this one regarding minimum top reinforcement and the reduction for bonded PT tendons?

 

[Retrograde]

Have you read the Addendum released a year or so later that clarified a few sections, including this one regarding minimum top reinforcement and the reduction for bonded PT tendons?

No I was not aware of the addendum. I'll have to try and get a copy. Thanks for the heads-up.

 

[KAR FUNG]

Hi rapt & Retrograde,

For your information, 0.075% is adopted for PT flat slab design and not for PT transfer plate design. Most of the PT transfer plate is designed under class 2, and tension is allowed. Furthermore, PT transfer plate is required to tie all the column during transfer force and subject to notional load act as horizontal force to PT transfer plate. Additionally, the presence of steel, either tensioned or untensioned, in the compression zone can be treated in a similar manner to the strain compatibility method described above for steel in tension zone. Based on the requirement, are we still consider the minimum reinforcement to be 0.075%.

Thanks