3 sided metal diaphragm
3 sided metal diaphragm
(OP)
We are currently designing a retail building that cannot use any braced frames along an entire front side of the building and the owner wants to stay away from moment connections because of cost. Can anyone point me to a reference regarding how to design a 3 sided metal deck flexible diaphragm (shear resisting elements on only 3 sides)? I've designed my share of rigid diaphragms that may not have shear resisting elements on all sides and can resist torsion, but I have not designed a flexible diaphragm with this requirement.






RE: 3 sided metal diaphragm
What do you call a "flexible diaphragm"?
You can achieve a diaphragm effect using diagonal bracing.
Have you tried to use a 3D analyse software?
Alternatively, you can design rigid connections between beams/columns along the facade (at top) and pin connection between columns/foundations (at bottom).
RE: 3 sided metal diaphragm
It has been my experience that flexible diaphragms cannot resist torsion and distribute shear loads based on trib only, where rigid diaphragms can resist torsion, and distribute shear based on shear resisting element relative stiffness.
Diagonal horizontal bracing is an option, but in this case will not do anything more than the diaphragm will for us.
We are using 3D software, but I'm not sure how that will help additionally here. Rigid connections are to be avoided because of cost.
RE: 3 sided metal diaphragm
However, I think most engineers would concede that such a diaphragm CAN function as open sided. For example, the IBC allows the design of open sided wood diaphragms, and wood diaphragms have been considered flexible in the past.
It gets down to your comfort level, as the engineer of record. Personally, I would be OK with designing an open sided steel deck diaphragm. If you are not completely comfortable with this, and you don't want a moment frame along the open side, you could design the columns on the open side as "flagpoles" (columns that cantilever from the base).
DaveAtkins
RE: 3 sided metal diaphragm
I think you are correct that this is done in practice and is valid way to go assuming small loadings. It would be nice to be able to hang my hat on something published.
Thanks for your help and very useful input.
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RE: 3 sided metal diaphragm
UcfSE- I called Vulcraft and got the info from them. I'm sure you could do the same. Otherwise I can email you the info.
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Thanks in advance,
YS
B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...
RE: 3 sided metal diaphragm
Thanks to all for your responses.
RE: 3 sided metal diaphragm