connecting RC foundation slab and RC footing

[n3jc]

Greetings, I have to make connections since settlements under RC foundation slab and footings will be different and Id like to avoid cracking (I m dealing with a masonry house with RC ties and beams).

Im wondering what do you suggest as the best way to connect footings (dimension 1 x 1 x 0,5 m) with RC slab (250 mm thick).

I was thinking about RC foundation beams but Im not really sure about details since RC slab is 250 mm thick and footings are 500 mm. Distance between a slab and footings is 5 m so 250 mm high beam will not be sufficient. I need a beam that is at least 500 mm high but there is a problem when it comes to connecting it to RC slab since slab is only 250 mm. What do you suggest?

Sorry for poor English. Thank you for help.

 

[KootK]

Given your proportions, I don't actually think that there's much point to the grade beams unless it's to tie things together laterally for seismic etc. There just won't be enough stiffness to really iron out any differential settlement issues. Is it the isolated footings that you expect to settle more? If so, I might address that by simply over-sizing them to keep settlement down.

 

[n3jc]

Thank you for reply!
I agree with you, but I was also thinking about connection to tie things together for seismic as you mentioned.

What Im strugling with is detail - connecting slab with foundation beams. I think making edge beam is the way to go...

 

[KootK]

1) I'd think that your edge beam would work fine.

2) A pair of short edge beams running back into the raft slab would be a more direct load path for lateral tie loads.

3) I lateral/seismic restraint is the only real purpose for the beams, I'd think that you could make the beams 250 mm deep to simplify formwork etc.

 

[n3jc]

Good stuff. Thanks for help.

regards