I am examining a high rise building project of 30 floors with a podium underneath and 2 basements. The structure in the tower and the podium varies between flat slabs, steel structure for wide spans, a huge shear wall around the tower's core, etc. The basement space has become inefficient as a parking area so I'd like to transfer this whole structure to an 8x8 or 16x16 grid of columns by using the transfer floor/slab. How can I estimate the required thickness of the transfer floor?
This is a common issue, especially considering the value of a parking space in cities like London. In principle, columns can be moved around to a certain extent using a transfer structure in order to improve the parking layout. However, as the commentators have pointed out, this depends on many factors and it is impossible to estimate the required thickness here.
The only reasonable solution is to work closely with the structural engineer to reach an acceptable column configuration. Better yet, if you have a good engineer, ask them to work out a configuration of columns/parking spaces which maximises the number of parking spaces. You may be surprised what they are able to come up with.