Shear peaks in piled raft foundation

[Myshell]

I am designing a piled raft foundation where columns are giving heavy point loads around 2500-3200kN. I have provided a raft slab of 1100mm required due to punching shear requirements as per Eurocode 1992-1-1 and tie beams of cross-section 1000mmx500 mm have been provided to reduce differential settlement of piles. I am getting some shear peaks at the location of column loads. I need your opinion that is it ok to neglect these peaks since the columns are resting on 1100 mm thick raft slab and also there is a 500mm deep beam underneath this load (total thickness 1600mm) and since crack pattern follows roughly an angle of 45 degrees, I donot need to check these peaks at a distance less than d for one way shear?

 

[KootK]

I suspect that you are fine here. I would recommend flipping the situation upside down in your head an then asking yourself what the right answer would be, per your local codes, if that were the case. That's been a useful trick for me in the past.

If at all possible, I think that it would be great if the tie beams could handle 100% of the local shear induced by the supported columns as one way shear. That, even if column support is not the reason for having the beams. I suspect that, near the points of column supports, the beams will tend to draw the lion's share of the load towards themselves by virtue of relative stiffness.

 

[CJLCivilStruct]

Curious as to what size structure is above? I only work on small foundations in comparison so seeing a raft of this scale is interesting to me.

I would agree that one way shear is to be checked 'd' away from the load point, so often the peaks are no longer an issue.