Addition to an existing RC building

[boricuastructural]

I have a 2-story RC building. A third story will be added an a 14ft expansion. The third story wil be be designed based on the existing columns and stuctural walls. Making a separate structure for the third story was considered but it was eliminated due to economics reasons. My question here is what are the seismic consideration of this type of connection between old and new structural member?

 

[JAE]

Not sure what exactly you are asking. With the addition comes added mass, added seismic demand, and a required review of the overall lateral load resisting system to ensure it has adequate capacity.

The connection between the existing and new will have to provide for any load path that proceeds through the interface. I would think also that this would tend to be a critical, rigid connection that would suggest using the system overstrength factors.

 

[boricuastructural]

Thanks. I already checked the lateral load resisting system with the addition. Provided addtional structural walls.

My question was more oriented to the detailing required for continuity of these members. Specially for columns.


You said "overstrength factors" you mean the UBC 1630.3.1 seismic amplification factors to account for structural overstrength?

 

[JAE]

Yes, - overstrength factor (IBC) is similar to amplification factor (UBC).