Reinforcement Detailing for Opening in Flat Slab and Beam

[DNod8]

Dear All,

I face a difficulty in doing the reinforcement details for the flat slab with opening. The opening that the Architect wants to put is for a scupper drain which have a width of 150 (on plan) and a depth of approximately 100mm (the drain is just to connect to the oil interceptor).

I know I did read somewhere that the opening should not be too near to the column head/drop panel because of shear or something in the flat slab. So I was thinking to suggest to the Architect to move the drain away from the stump area. However my colleague suggested the detail to be as per attached. Oh yeah, we designed the slab as flat slab.

The other thing is about the opening in the beam. How would the detailing be like for the reinforcement around the opening if the scupper drain is located 600mm away from the support of the beam, and at the suppport there is a moment and if I put an opening there, my top reinforcement of them beam will be disconnected. Please advice.

Would appreciate you suggestions and thought.

Thank you.



a trainee who wants to learn and learn

 

[mike20793]

You need to move the drain away from the column. You may run into issues with live load deflection of the slab between the columns and ponding and also the shear issue you mentioned. This depends on the roof live load and the roof detail from the architect (tapered insulation depth, slope, etc.). Also, I would definitely not put an vertical opening in a beam. You're going to run into issues with your compression block and may interrupt your reinforcing, as you suggested. It should be much easier to move it, then to detail for it.

 

[hokie66]

Based on your picture, that doesn't look like a problem. The recess is small, and a fair way from the column/pile. But not knowing more about the slab and the "oil interceptor", I could be wrong. I think mike20793's comments assumed this is a roof slab.

As to an opening in a beam of the same size, you can't just "disconnect" the reinforcement. You would have to provide bars to ensure the continuity of the flexural strength.

 

[Archie264]

See link for guidance on openings in slabs:

http://www.structurepoint.org/publication/pdf/PCA-Concrete-Floor-Slab-Openings.pdf

As noted above, trying to put openings in beams is problematic (translation: a bad idea).

 

[DNod8]

thanks all! Yup, now I got it. Putting a hole within the the 1/3 of the span from support is a big no, thanks for reminding me of that.

and Archie264, a great link there, thanks for sharing.

a trainee who wants to learn and learn