Hole in existing slab 3

[Jandra11]

what are the requirements on making a hole in a existing slab, is there any restricted area for example near the column?. and what are the things need to be check??

 

[dik]

How big a hole? and, what's the purpose?

Dik

 

[Heldbaum]

Go to 13.4 in ACI 318-11 "Openings in slab systems"

 

[racookpe1978]

Yes.

The requirements are:
1. Make a new hole big enough to serve the new purpose - whatever that new purpose may be.

2. Do not create a failure by creating a hole in the slab/floor/concrete/existing reinforcement/existing building/existing stress and settlement situation.

Seems simple, doesn't it?

ANALYZE the specific situation for ALL known and ALL unknown loads that "might" occur now, in the past due to operator error or original design or construction error or future operator error!

This is NOT "quote the book" so-called design.
It IS REAL engineering!

 

[WARose]

In general, you will be checking the following questions:

1. How much flexural steel (if any) will I be interrupting from this opening and can the rest of the steel take care of it?

2. What effect on shear does this have? Specifically, will this opening cut back on my punching shear area at the column? (It can affect one-way shear as well but that seldom controls.)

3. [If any moment is transferred at the column...] How much unbalance in the moment is created? You will have to think about a pattern load with this and the possible increase in shear from a unbalanced/transfer moment.

4. What kind of coating system will I need to protect the exposed re-bar and concrete from the environment?

ACI 352.1 R-89 is a good resource on openings:

http://civilwares.free.fr/ACI/MCP04/3521r_89.pdf

 

[Jandra11]

thanks for all the response. its a 600x500 hole for the kitchen exhaust duct.

 

[dragstrut]

Here is a great resource.

the bottom line: know what you are doing before you start blowing holes through slabs! Its the wild west as far as I'm concerned, and you want to be experience in gun slinging if you're venturing down that road.

https://www.structurepoint.org/publication/pdf/pca-concrete-floor-slab-openings.pdf

 

[hokie66]

Jandra11,
You have asked a structural question, but have shown us a part architectural plan. That doesn't help. If we could see the structural drawings, we might be able to give some useful advice.

 

[Jandra11]

@dragstrut thank you for the great resource

@hookie sorry i just use this one to show the size of the hole and its location btw this the structural drawing that i have. Link

 

[Jandra11]

there will be a perimeter beam, does it mean punching is not critical on this scenario?