Hello. My suggestions: --Leave enough (dilatation) space between the two structures, --Calculate the structures separately, if necessary, you can solve the foundation together, --Check the elevator engine room, --1. Remove basement rigidity tick, --Insert tie beam between individual foundations, --Insert horizontal soil load on outer shears, --Make finite element width 0.25 m in slabs, --4. Create the stairwells on the floor with the floor edge, --25/50 beams do not get stuck in 50/35(36) beams -Brain the stairs, --2. remove the curtains that do not connect to the building with flooring in the basement, and get an account done, Ünver ÖZCAN