Diaphragm Tributary
Diaphragm Tributary
(OP)
Folks,
In designing diaphragms, ASCE 7 requires you to calculate the weight tributary to the diaphragm. Please see attached sketch. I am trying to determine which value is to be used in calculating the diaphragm force.
In designing diaphragms, ASCE 7 requires you to calculate the weight tributary to the diaphragm. Please see attached sketch. I am trying to determine which value is to be used in calculating the diaphragm force.






RE: Diaphragm Tributary
And I would not assume the base of the wall is fixed.
DaveAtkins
RE: Diaphragm Tributary
In Breyer's textbooks, he uses tributary. However, he says that the wall only spans to the roof (He is not assuming a propped cantilever). What the tributary is probably depends on the kind of connection at the diaphragm? Simple spans or continuous across the diaphragm.
In other references, they use the reaction from a propped cantilever.
RE: Diaphragm Tributary
Unless you're doing some kind of unique design, the wall reinforcing will make the wall act as a cantilevered beam. pinned at bottom and at roof.
Now if you're tying bars into the roof or in some other way making the roof a moment connection, then all bets are off.
RE: Diaphragm Tributary
If, on the other hand, the wall is discontinuous at the diaphragm (which you might have with interrupted studs which are kicked back down to the diaphragm), then I would use 1/2 story height + parapet.
RE: Diaphragm Tributary
To be honest I've done my analysis both ways. Often I'll use the tributary method just because its faster and usually pretty close. The more off the cuff you are just remember to leave yourself a little bit more factor of safety to cover yourself.
John Southard, M.S., P.E.
http://www.pdhlibrary.com
RE: Diaphragm Tributary
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Diaphragm Tributary
I am unfamiliar with the Breyer textbook.
RE: Diaphragm Tributary
RE: Diaphragm Tributary
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask