cracks in a flat slab
cracks in a flat slab
(OP)
Dear All
I have observed few cracks for the flat slab system. I am attaching the photos herewith. It is a very peculiar crack and is a through crack i.e. propagates through the full depth. To me it looks like a shrinkage crack.
Please advise
Thanks in advance.
I have observed few cracks for the flat slab system. I am attaching the photos herewith. It is a very peculiar crack and is a through crack i.e. propagates through the full depth. To me it looks like a shrinkage crack.
Please advise
Thanks in advance.





RE: cracks in a flat slab
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com
RE: cracks in a flat slab
What is going on with that construction? It appears that a section has been cut out, and you are preparing to cast a new section at a lower level.
The creation of the opening would have caused a stress riser for the preexisting tension in the slab, thus the crack formed at that position.
We certainly can't tell from here the severity of the situation.
RE: cracks in a flat slab
RE: cracks in a flat slab
Hereby I am attaching the snapshot of the drawing where the exact location and profile of the crack is marked. Also the surrounding portion is shown for clarity.
Regards
RE: cracks in a flat slab
Is the slab RC or PT?
If PT is it banded/distributed distribution? Which directions?
When did the crack happen? Were any large construction loads applied?
Is the crack full depth or only in the bottom?
We need information if you want any sensible answers.
RE: cracks in a flat slab
The spans were designed as a continuous span. It is a RC slab. As per the site staff, crack happened 2-3 weeks after the shuttering was removed.
The crack is full depth.
Regards
RE: cracks in a flat slab
RE: cracks in a flat slab
RE: cracks in a flat slab
Is it a slab set down of some magnitude, a full-depth slab opening?
RE: cracks in a flat slab
From the original picture, it is a full depth opening for some reason.
nidhimenon,
If full depth, then it is shrinkage related, but could also be related as well to overstress due to that area being reinforced as continuous but actually being a simply supported end combined with shrinkage. Agree also that it looks short on reinforcement. How wide is the crack? What are the span lengths, how much reinforcement is in there and what is the reinforcement layout?
It would make our life easy if you told us everything and engineer would need to know to comment on something like this.
RE: cracks in a flat slab
I think you are correct - probable combination of restraint-to-shrinkage and the end condition created by a dominant opening.
Still cannot understand the slab opening with two columns and an extended drop panel in the middle of the opening, as per the ORANGE clouded area below:
RE: cracks in a flat slab
Dik
RE: cracks in a flat slab
RE: cracks in a flat slab
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: cracks in a flat slab