Rooftop Penthouse Design

[sgs114]

Hello,

I have a question with regards to the design of rooftop penthouses. When designing these rooftop structures, do you typically (won't say always) use Section 13.3 for design of the structure regardless of what your lateral system of the roof top structure is (ie cantilever column or metal stud walls)? Are you able to design the rooftop structures using provision in CH 12 instead to try and lower your seismic coefficient (relative to the penthouse weight)?

SGS

 

[r13]

I think it is an "either, or" and "depends" question - size, how it is connected, connected to what?

 

[HTURKAK]

My answer is noyes..it depends on how it framed. If the penthouse framed and extension of main
the building frame the analysis and design shall be as per CH 12. If the penthouse light construction architectural componenet , in this case 13.3 is applicable.

Regarding lowering the seismic coefficient , i have copy and pasted note A of Table 13.5-1 Coefficients for Architectural Components

'A lower value for ap shall not be used unless justified by detailed dynamic analysis. The value for ap shall not be less than 1. The value of ap =1 is for rigid components and rigidly attached components. The value of ap =2½ is for flexible components and flexibly attached components.'