(1). Structure Aspect Ratios
The Horizontal/plan aspect ratio (Length to Width ratio) of the side block is 160/18=8.8 While its vertical/slenderness ratio (height to width ratio) is 60/18=3.33
I didn't come across any code limitations regarding these ratios But an indian research paper "Effect of Aspect Ratio & Plan Configurations on Seismic Performance of Multistoreyed Regular R.C.C. Buildings: An Evaluation by Static Analysis" concludes that,
(a) The buildings with Horizontal Aspect Ratios 4 or less than 4, the seismic performance is reasonable. Above this, the worse effects of excessive forces, storey drift and displacement values may be obtained. Hence they should be discarded due to their unsatisfactory, weaker and unreasonable performances on the bases of above seismic parameters, which can cause detrimental and disastrous effects or otherwise be treated with the enough earthquake resistant elements.
(b) The buildings with Vertical Aspect Ratios less than 4, the seismic performance is reasonable. Above this, the worse effects of excessive overturning, storey drift and displacement, period of vibration, etc. values may cause detrimental and disastrous effects to the buildings. Hence slender building configuration, as far as possible, should not be chosen, or otherwise be provided with the adequate earthquake resistant solutions.
(2). Flexible Tower on Rigid podium
UBC-97 Section 1629.8.3 item 4 says
"Structures having a flexible upper portion supported on a rigid lower portion where both portions of the structure considered
separately can be classified as being regular, the average story stiffness of the lower portion is at least 10 times the average
story stiffness of the upper portion and the period of the entire structure is not greater than 1.1 times the period of the upper portion
considered as a separate structure fixed at the base."
And UBC-97 Section 1630.4.2 Item 2 says
2. The following two-stage static analysis procedures may be used for structures conforming to Section 1629.8.3, Item 4.
2.1 The flexible upper portion shall be designed as a separate structure, supported laterally by the rigid lower
portion, using the appropriate values of R and ρ.
2.2 The rigid lower portion shall be designed as a separate structure using the appropriate values of R and rho. The
reactions from the upper portion shall be those determined from the analysis of the upper portion amplified
by the ratio of the (R/ρ ) of the upper portion over (R/ρ ) of the lower portion.