Cantilever Flexible Diaphragms

[abusementpark]

What are your limitations when cantilevering a flexible diaphragms? Theoretically, are you even supposed to do this at all?

Obviously, a little cantilever will be fine, but how much can you push it??

 

[asixth]

What is your flexible diaphragm that you are trying to cantilever?

 

[Bobber1]

At one time, wood framed cantilevered horizontal diaphragms were limited by code to a 25 foot cantilever. Sorry I don't have time to look it up right now.

 

[lsmfse]

I think it is defined in the IBC- I do remember the limit as 25 feet so long as your diaphragm ratio is 1:1(I think, don't have code in front of me) Also, cant. wood diaphragms are not allowed to resist lateral forces due to conc. or masonry.

 

[OzEng80]

I recall a backspan limit from somewhere as well - i think the cantilever was limited to a third of the backspan.

 

[msquared48]

I recall a 20 X 20 limitation.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Prestressed Guy]

The appropriate section in the 2006 IBC was 2305.2.5 Rigid Diaphragms. This section has been removed from the 2009 code. You now have to look in the AF&PA SDPWS section 4.2.5.2. The limits are the greater of 25’ or 2/3 x width.