Different flat slab thickness

[djzzz]

Greetings to all,
I am currently doing a design for a G+Mezanine+3floors+roof. Here I am using flat slab as the its a multi purpose building so the wall to wall doesn't match. Ground 7 mezzanine floors have lots of vacant space were as 1st to 3rd floors are accommodation. so there are brick wall etc. So more load is coming in level 1st to 3rd. More thickness shall be considered for 1st to 3rd floor. I am considering 250mm thick slab for mezzanine, 290mm thick slab for 1st to 3rd. Intermediate columns also present. Is it ok if I consider lesser thickness for the mezzanine floor and greater thickness for 1st to 3rd.
Need your advise. Guys please help me out.

Firoz

 

[ztengguy]

Lesser thickness is ok if it works for the design, and meets code requirements

 

[jayrod12]

Don't change your thickness without checking with the archtitect. you know for a fact their going to find some stupid reason it's an issue for them even if you get the top of floor elevation to match.

 

[djzzz]

Thank you guys for your suggestions. Can you tell which code to refer and where. just wanna be on the safer side.

 

[rowingengineer]

i dont think there is a specific code clause that deals with different thinkness's vertically in a building. as long as this dosnt create a soft storey than i can see no reason why normal analysis of the earthquake design wouldnt suffice.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[steellion]

Weigh the benefits of keeping the slab thickness the same for simplicity of construction vs. material savings. It is not always prudent to design to the gnat's posterior if it makes life more difficult for the contractor.

 

[apsix]

FZHSK
You state 'mezzanine floors have lots of vacant space'. Designing for loading dictated by a specified use is acceptable, but it's likely that current vacant space will end up as used space sometime in the future.
A reasonable imposed load must be allowed for, but I would ask the architect/client for an specific requirements re future-proofing.

 

[JLNJ]

Ask a concrete contractor which is more cost effective. The might surprise you with their insight.