h = slab thickness
ln = clear span of slab in the direction examined
TBDY 2018 guides TS 500 for 7.11.2 thickness of flat slab. The following explanations are included in TS 500 11.4.2 design principles section:
The thickness of flat slabs operating in two directions can not be less than the following value.
For floors without beams, h ≥ l n / 30 and h ≥ 180 mm
Flat slab thickness should be selected in a way that it does not require punching reinforcement.
Selected slab thickness: 27 cm