step downs in waffle pods

[flyingdebris]

I was under the impression that step downs in waffle pod slabs would also require the pad to be stepped down to maintain a constant beam depth. this is how i see it in the standard details given in as2870. for example, if we have a 385mm deep waffle slab with say an 85mm step down to a corner patio to the back of the house or even a garage step down, would you not have to lower the finished pad level by 85mm to maintain the 385mm beam depth (not mentioning the appropriate lap distance behind the line of step down as well). what about a 50-70mm shower setdown in the middle of your slab? Do you just drop back a pod size or do you lower the finished pad height locally around the set downs??

Always thought lowering the pad with the step downs was a must. Getting told otherwise. Am i wrong or do I have lazy/incorrect builders?? Any thoughts guys?

 

[aaronPTeng]

For the monkey see monkey do approach as it is called in the code (No disrespect as it is what I do for houses) I agree with you step it down.
What I have seen done before is for example an M class, they do the 385 slab (300 pods) then in the garage or set down areas go down to the 310mm slab (225mm pod)
so at minimum you have the M class requirements.

Otherwise you would have to model and analysis the lab if you go thinner than required by as 2870-2011. However I typically do multistory developments so I am sure there are more experienced residential engineers on here who can correct me if I am wrong.

"Structural Engineering is the Art of moulding materials we do not wholly understand into shapes we cannot precisely analyse, so as to withstand forces we cannot really assess, in such a way that the community at large has no reason to suspect the extent of our ignorance." Dr. Dykes, 1976

 

[flyingdebris]

thanks for input aaron. not keen on lowering waffle slab thicknesses any lower than they are through analysis. they are thin enough. Just trying to do work with the info we are given. it makes perfect logical sense to lower pad depth with step downs. builder telling me he has never done this before with any other engineer he has dealt with in the last 500 slabs he's done. do i tell him that his last 500 slabs are wrong? he shows me plans of another engineers which clearly shows the lowered pad level at the step down and I show him the detail and he says that his engineer doesnt worry about it on site.

 

[rowingengineer]

Most of the inspection are handled by building surveyors in my areas these days and some of them make engineering judgement changes to my documents that I find interesting. So while I do have have this detail as well, who knows if it gets used.

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."

 

[flyingdebris]

rowing, understand what you are saying there. i know for sure it happens a lot. i will take your diplomatic answer as a "yes you agree with me".