Wood Diaphragms - Cantilevered & Open Front Structures
Wood Diaphragms - Cantilevered & Open Front Structures
(OP)
I am working on a design where the front portion of the building will not be able to resist lateral loads due to multiple openings, aspect ratio limitations, and shape irregularities. I decided to look at designing this an open front structure with three shear walls. However, the roof diaphragm will cantilever ~25'. I know there are two different configurations listed in SDPWS in sections 4.2.5 (Open Front Structure) & 4.2.6 (Cantilevered Building). Is it applicable to design these two systems in conjunction with each other? It seems to me that the wood diaphragm would not have the stiffness or rigidity to transfer loads at the cantilevered portion, but I may be wrong. Has anyone ever came across a situation like this?






RE: Wood Diaphragms - Cantilevered & Open Front Structures
RE: Wood Diaphragms - Cantilevered & Open Front Structures
Mike McCann, PE, SE (WA)
RE: Wood Diaphragms - Cantilevered & Open Front Structures
RE: Wood Diaphragms - Cantilevered & Open Front Structures
In my mind this means, the gravity system should be design for P-Delta effects probably of the anticipated inelastic deflections. But, also their connections should be capable of withstanding the large deformations as well.
It's an interesting theoretical exercise to get an open front / cantilever diaphragm like this to work. But, it is not generally a good thing to do in practice.
RE: Wood Diaphragms - Cantilevered & Open Front Structures
RE: Wood Diaphragms - Cantilevered & Open Front Structures
RE: Wood Diaphragms - Cantilevered & Open Front Structures
RE: Wood Diaphragms - Cantilevered & Open Front Structures
You can get away with a 35' cantilever if you check the deflection and rotation. Read up in the 2015 sdpws. It is a free download if you don't have it.
That steel frame is going to get VE'd out right away. That and it will cause settlement issues. Also, the delfection on a frame is going to have to be very tight in order to make it play well with interior shear walls.
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: Wood Diaphragms - Cantilevered & Open Front Structures