Cantilever Transfer Slab, Would you design it this way? 5

[I-I]

I have uploaded a sketch below showing the project I am designing, This transfer slab is going to support 5 stories above. Because there are bedroom above and I couldn't shift the columns above inwards so I have to put them on external and being supported by this transfer slab. The loads of each column above is roughly 200kN (Dead plus Live). Although I am not the one to design the PT transfer slab, I am not comfortable with this arrangement. But at the same time, I cannot shift the columns above 3.2 m inwards. (The columns below cannot move outwards they are on the external already, outside of them are roads)
What is your thoughts on this?

 

[I-I]

Sorry been away for a few days and just got back! Thank you everyone. Much appreciated!

 

[I-I]

So the idea of the haunch beam or this wall version is to increase the moment capacity in NS direction correct? I will see if the architect is happy with this or even just put two column here instead of one.

That said, I have seen discussion about PT tendons and the robustness of corner column. But what about the left handed structure with 2 internal columns? Isn't robustness still a concern here? (ie one of them fail will lead to the collapse of stories above as well). Speaking of robustness, I am not sure if I fully understand what it means. Doesn't transfer slab/beam have robustness issue as well? For example, the failure of a single span transfer beam will lead to the collapse of structure above so why is it allowed?

I have one more question regarding the internal two-column system. The client prefer using precast short wall for some of them (say about 1 meter long). But we are relying the axial force couple to achieve the balance and due to the unequal transfer loads from above (especially when live load pattern is taken into consideration), one of the lower columns might be in tension. Is that a concern for precast due to the wall-slab connection?

 

[I-I]

Yes, the slab will be designed by other PT contractor. We will discuss with the PT at later stage after we set out the structural plan. I am not very familiar with PT to be honest but I do learn something from the discussion above!

 

[dhengr]

I-I:
That’s just not smart structural design however you cut it or finesse it. I would look for another Arch. client, and let some other sucker explain what’s going wrong with that (the Arch’s.) bldg. and the deflections. etc., even before the building is even complete and occupied.

 

[MIStructE_IRE]

I suggest you get your PT guy on board now, not later. Punching/deflections/slab thickness all need to be understood at this stage.

PS - Someone needs to give that architect a slap!

 

[I-I]

What about the inner two-column system? What if I change the corner column from one to two then? Is robustness still an issue?

 

[I-I]

Unfortunately I cannot choose the client cuz I just worked here...

 

[r13]

I-I,

Can you post the entire floor plan, so maybe we can make better sense/comment on it. I wouldn't blame anybody for develop an odd shaped property, and tying to maximize the utilization area. What is the planned use of the first floor, why the seemly excessive cantilever over it? Back to home, roofed sidewalk was mandatory for commercial buildings then.