IS IT IMPORTANT TO USE STRUCTURAL JOINT
IS IT IMPORTANT TO USE STRUCTURAL JOINT
(OP)
DEAR STRUCTURAL
I have a flat slab without beams 10m*90m , rectangular , dose i have to use a structural joint in that
I have a flat slab without beams 10m*90m , rectangular , dose i have to use a structural joint in that






RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
You can have a large flat slab like this in either case without structural joints, but it takes compensation for temperature and shrinkage as well as general concrete cracking through other means. Shrinkage compensating admixtures, post-tensioning, proper concrete mix design, etc.
Curing will not reduce the total shrinkage cracking, but in fact may delay the onset of the total plastic shrinkage component. Often that leads to greater cracking once components are "locked in" on site.
Post more details; There are lots of people around to help!
Cheers,
YS
B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
This is a very old and well known problem.... If you prop a flat slab, it will behave as if there were beams along the shortest connecting points between columns. The cracks won't be as big, or deep, or as well located, but they will occur.
Whether or not they are significant depends on too many factors to try and help you with my limited experience. Sorry, and good luck, but I'm just an observer from here on in.
Cheers,
YS
B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
Thanks for the compliment, but 1966 is the year I graduated from University. You need to determine first if the cracks are structurally significant before you consider any remedial action. Without further description of the structure, I am afraid that I can't be of further assistance.
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
I would expect the cracks to become wider in cooler weather, and have no explanation for why they would widen in hot weather.
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
Maybe you should listen to what others are saying/asking. You have to determine if the cracking is structural or restraint induced. Then you have to decide if the structure is adequate. Just epoxying the cracks will not help it if it is not structurally adequate.
Is the slab still supported on formwork/falsework?
Is there any top reinforcement at all, in either direction?
Is it reinforced or prestressed?
Are there any edge beams? Is the slab acting in one way or 2 way action? If it is 2way action, there has to be top reinforcement to make it structurally adequate. If it is not prestressed it is too thin to span 10m simply supported!
No-one on this list and no responsible engineer can help you without a lot more information, no matter how nicely you think they have responded.
Also, a 300mm slab is too thick to reinforce in one face only for shrinkage and temperature.
RE: IS IT IMPORTANT TO USE STRUCTURAL JOINT
and i read what the friends answer carefully