Expansion joints in Irregular shaped buildings

[fvs]

I am designing 2 concrete towers placed in an L-configuration. The towers are connected only at the 2nd level of their 15 storey height. One of the L legs is 81m long and the other is 60m, at the connected level.
Does anyone know of any criteria governing the provision of expansion joints in the 2nd level slab to isolate the lateral movement of the 2 towers?

 

[JAE]

Are you dealing with seismic? If so, most building codes will take your "L" shaped portion and classify it as an irregular building - thus increasing your lateral loads.

 

[fvs]

Both wind and seismic loads. I am already dealing with magnified loads to account for irregularity. But is that enough?

 

[JAE]

Well, I would think that you would have to take the full lateral shear from each of the two wings and direct them opposite to one another (sum of the base shear forces at the second level) and design for the tensile forces in your second floor diaphragm.

This is because your two wings will undoubtably have different periods, T, and thus the potential for each wing to cycle in opposite directions during a seismic event.

You would also have to include the sum of the sway deflections at the top to ensure that the two wings don't bang against each other.

 

[Rawand]

Dear FVS
it is Illogical to connect high buildings in only 1 level Irrigular they or not.
Irrigular buildings must be divided completely to make allowance for sway when subjected to wind blows or earthquakes. I suggest that the connection block (if any) be simple supported on cantilevers from both sides