Gus14
Civil/Environmental
- Mar 21, 2020
- 194
I've seen many cases where a raft foundation of 20 cm thickness is used and an additional drop-in thickness between 30 to 40 cm is employed beneath each column to improve shear capacity. This overall raft depth 20 cm serves as a basement floor. My questions are :
1) Is there a provision regarding the ratio between the local thickening depth and the overall raft thickness "the 20 cm"?
2) How would the raft behave differently if I increase the overall raft depth from 20 cm to 30 cm? ( asking to know what to expect from software analysis )
3) As a design methodology, I met engineers who regard each column as a single footing and ignore this 20 cm raft that connects everything. and still, they heavily reinforced the raft with top and bottom reinforcement ( 7 Y 12mm top and bottom ) what do you think about that?
4) If only to have a basement floor don't you think that 20 cm with a heavy reinforcement is too much, as it would logically be treated as a slab on grade and barely require any reinforcement for typical uniform dead and live loads?
1) Is there a provision regarding the ratio between the local thickening depth and the overall raft thickness "the 20 cm"?
2) How would the raft behave differently if I increase the overall raft depth from 20 cm to 30 cm? ( asking to know what to expect from software analysis )
3) As a design methodology, I met engineers who regard each column as a single footing and ignore this 20 cm raft that connects everything. and still, they heavily reinforced the raft with top and bottom reinforcement ( 7 Y 12mm top and bottom ) what do you think about that?
4) If only to have a basement floor don't you think that 20 cm with a heavy reinforcement is too much, as it would logically be treated as a slab on grade and barely require any reinforcement for typical uniform dead and live loads?