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Discontinuous diaphragm?

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Please bear with me with this explanation.


Two story building with upper floor dimensions of 22’x52’.

Lower floor dimensions of 15’x52’ with a 7’ terrace at the upper floor.

The upper floor bearing/shear wall is supported on a timber beam at the 22’ width.

The plywood diaphragm at the terrace is 1” lower than the upper floor and is supported by a ledger nailed to the side of the timber beam, therefore the vertical discontinuity.

The diaphragm at the upper floor is nailed to the top of the beam.

There are no shear walls in line with the timber beam.


My first inclination is that the diaphragm is discontinuous and therefore there are two “cantilevered” diaphragms transferring the lateral shear from the upper floor to the lower floor shear walls at each side (the 52’ dimension).


Or, is there a way to construct the 1” vertical offset so the diaphragm can be considered continuous across the beam?


Hopefully this makes sense.






Joseph R. Grill, P.E. (Structural)

Shephard - Wesnitzer, Inc.

Civil Engineering and Surveying

P.O. Box 3924

Sedona, AZ  86340

PHONE (928) 282-1061

FAX (928) 282-2058