1 way shear /punching shear in raft foundation for core and outer RCC wall 1

[Ali Abidi]

Dear all,

Could anyone guide me on how to check 1 way shear /punching shear in raft foundation for core wall and outer wall for a building attached here(AutoCad file attached). It is a 18 story building with mivan shuttering. Raft thickness is 900mm. I am designing it in SAFE.

your immediate feedback regarding to the matter subjected will highly be appreciated .
Thanks in Advance

Regard's
Ali

 

[KootK]

That's a question that's been kicked around for debate a fair bit over the last few years. My understanding of the state of the art is this:

1) If the wall/core flexural design assumed the development of a compression block at one end, then punching shear and one way shear should be checked treating that compression block as an isolated compression element, similar to a column.

2) It's generally thought to be unrealistic to assume that hugely wide swaths of mat foundation participate in one way shear resistance. Rather, current practice is to assume an effective one way shear widths of [delivering element widths + 1 x slab depth each side].

3) One way shear stress is checked at [1 X SRQT(f'c)] if there is no shear reinforcement present in the mat. This is probably a bit conservative but, apparently, [2 X SRQT(f'c)] is a bit unconservative.



I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.