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Prevent RISA-3D from Defining a Diaphragm from RISA Floor

Prevent RISA-3D from Defining a Diaphragm from RISA Floor

Prevent RISA-3D from Defining a Diaphragm from RISA Floor

(OP)
I'm working on a very preliminary analysis on a new single story structural steel building with a metal deck roof. My intentions for the building when I get into final design is to utilize horizontal roof bracing and vertical bracing in the walls. I don't want to use the metal deck as a diaphragm. I started in RISA Floor to analyze the roof framing, defining a metal deck to apply my gravity loads. However, when I move to RISA-3D, I don't want the program to automatically define the diaphragm and the diaphragm lateral loading. I'll handle the lateral loading myself. Is there a way to prevent RISA Floor and RISA-3D from automatically defining a diaphragm, or should I have started from RISA 3-D from the begining?

RE: Prevent RISA-3D from Defining a Diaphragm from RISA Floor

Some thoughts on this subject:
1) When you are in RISA-3D you can always make your diaphragm "inactive" there is a flag on the Diaphragms or Floor Diaphragms spreadsheet.

2) Alternatively, you could switch the diaphragm type to "flexible". This means that the diaphragm will not have any stiffness. Any wind or seismic load that gets generated would still be attributed to the lateral frames, though.

3) If you want to prevent the program from applying wind and seismic forces to the diaphragm, just switch the wind and seismic codes to None. The program will no longer generate these forces.

RE: Prevent RISA-3D from Defining a Diaphragm from RISA Floor

(OP)
Awesome...Thanks for the tips, Josh!

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