Structural question 1

[faisal45]

Dear All,

is there any problem of designing two way slab having thickness 8 inches though other adjacent slab thickness are 6" and 5"?

what kind of consideration i will take while performing the slab design?

Thank you.

Regards

Engr. Faisal

 

[SethGuthrie]

I see no problem to design two way concrete slabs where the thickness changes in places, it happens all the time with balconies, for example. Consideration of eccentricity may be important for a change of 2-3 inches assuming the concrete slabs are flush on one side and not concentric.

RAM Concept is one application that makes the design of such slabs easy.

 

[MiketheEngineer]

Are you double posting??

 

[dik]

It's easy to do... if you have many of them, try to keep the step to the dimension of your form thickness and nominal dimensioned lumber... eg., if your form thickness is 3/4" and your nominal dimensioned lumber is 1", the step should be 3/4" + 3/4"... or if your nom dim lumber is 2" then the step should be 3/4" + 1-1/2".

Different question, Mike... maybe same project.

Dik

 

[asixth]

There is no problem with doing so. Is it from the floor plan of your other post. I would just have a 8" slab for the entire area and then 6" for the balconies. Flat soffit is easily formed.

 

[msquared48]

Shouldn't be a problem in this circumstance.

If you were dealing eith a major haunch though, bending the rebar through the haunch, you might have to install radial tension bars at the link to keep the rebar from wanting to pop out of the slab.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[faisal45]

i bent the bottom rebar of 8" slab and extend the bottom rebar of 6 " slab.
thnx dik i will take care of the formwork.. .

@ mike nope its a different project with different problems.

 

[asixth]

Don't think it is so critical for flat slab design with small steps. I read a research paper the other day for dapped end beams which suggested that the hanging force at a change in cross section is equal to the shear force.