Crack on flat plate

[Adrielle]

Dear guys,

There is a crack appeared on my balcony since 2 years. My point of view is not a shear crack. The balcony has a lot of snow in the winter time and crack seem stable (does not continue to open more). I think this is a flexure crack. In the last photo, the crack is on the left corner.

What do you think? Should I install an I beam below the slab to reinforce it? or what your advise about the solution to repair it with the lowest cost. Thank you.

Here is some photos of the crack:

 

[dik]

Looks like a torsional crack; is your slab cast into the balcony beam, and with deflection is putting a torsional load on to the beam.

Dik

 

[Adrielle]

There is no beam. But I think slab is cast into the wall where there is garage door.

 

[dik]

It could be a torsional moment or torsional flexural moment where the slab meets the column... and no reinforcing to resist.

dik

 

[Adrielle]

What is your advise to reinforce the slab?

 

[dik]

That's trickier... talk to a contractor that specialises in epoxy injection, or, alternatively put a small beam in to support the slab... maybe a HDG W6x15 or something of that ilk.

Dik

 

[Adrielle]

Thank you. I intend to put a small beam to support the slab.

 

[dik]

Use a good coating or HDG...

Dik

 

[hokie66]

I agree with your assesment that the crack is flexural. The top reinforcement in that corner has not been enough to restrain the slab/column moment.

You need to seal the crack, especially since freezing is going to remain a problem. Epoxy injection would be my choice. I don't think I would be adding a steel beam under the edge unless things get worse. Which side would the beam go on? Is there any cracking on the opposite corner?

What is the construction of that cantilevered balcony up top? Those are the ones which have a history of catastrophic colllapse, and should have close monitoring.

 

[Adrielle]

Thank you for your answer. I also think that the top reinforcement has not been enough. Since two years, the crack is still the same. And only this corner has this problem. So you think that Epoxy injection is enough to resolve it?

 

[Adrielle]

I would put the beam under the longer edge but it will reduce the clear height of garage entrance.
Don't worry about the upper balcony. It has been supported by 5 cantilevered chanels C8x11.5

 

[hokie66]

I would inject the crack and monitor it. If it hasn't opened in the last two years, it has a very good chance of remaining stable.

 

[hoshang]

is your slab cast into the balcony beam

The thread's name is
Crack on flat plate

 

[rapt]

I do not think anyone should be advising anything without more information on the connection details to the column.

Reinforcement layout and end development etc.

If the reinforcement is not developed properly, epoxy injection will not help in the long term.

It should be reviewed by a structural engineer.

 

[Adrielle]

It's residentiel house. I don't have any information about reinforcement. I think there is not enough top reinforcement at this corner. I attach the balcony view plan that I draw myself.

My objectif is to find a solution that is economic but work.