Lateral Buckling Restraint - Steel Members
Lateral Buckling Restraint - Steel Members
(OP)
Hi,
I am currently designing a partition wall system with cold formed steel PFCs that contain horizontally stacked AAC (Autoclaved Aerated Concrete) panels.
My question is in regards to whether my fixing arrangement allows for the PFC flanges to be laterally restrained so that I can take the full section capacity (for flexure) of the PFCs as opposed to the member capacity, which considers the buckling effect of the member.
The panels fit snugly into the PFCs and my proposal is to fix screws through the web of the PFC that fixes the AAC panels to the PFCs.
My theoretical understanding and experience tells me that this connection (Connection A) is sufficient to restrain the flanges - which will allow me to design using the full section capacity.
I cannot see how these PFC members can buckle using connection A - however I just need to confirm this for my detail.
I am hoping to not use connection B as this involves double the amount of the screw fixtures.
Would I be able to use connection A and design the PFC to contain the full section capacity??
Thanks.
I am currently designing a partition wall system with cold formed steel PFCs that contain horizontally stacked AAC (Autoclaved Aerated Concrete) panels.
My question is in regards to whether my fixing arrangement allows for the PFC flanges to be laterally restrained so that I can take the full section capacity (for flexure) of the PFCs as opposed to the member capacity, which considers the buckling effect of the member.
The panels fit snugly into the PFCs and my proposal is to fix screws through the web of the PFC that fixes the AAC panels to the PFCs.
My theoretical understanding and experience tells me that this connection (Connection A) is sufficient to restrain the flanges - which will allow me to design using the full section capacity.
I cannot see how these PFC members can buckle using connection A - however I just need to confirm this for my detail.
I am hoping to not use connection B as this involves double the amount of the screw fixtures.
Would I be able to use connection A and design the PFC to contain the full section capacity??
Thanks.






RE: Lateral Buckling Restraint - Steel Members
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Lateral Buckling Restraint - Steel Members
BA
RE: Lateral Buckling Restraint - Steel Members
If Connection A requires a closer spacing of fasteners than Connection B, there may not be much saving in using A.
BA
RE: Lateral Buckling Restraint - Steel Members
I don't understand, KootK; Could you expand on that?
BA
RE: Lateral Buckling Restraint - Steel Members
Doh. That response was intended for an altogether different thread. My bad. Egg nog on the brain.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Lateral Buckling Restraint - Steel Members
RE: Lateral Buckling Restraint - Steel Members
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Lateral Buckling Restraint - Steel Members
RE: Lateral Buckling Restraint - Steel Members
So I agree with BAretired assessment, check if the fasteners and web stiffness qualify as a compression flange brace. AAC is pretty weak remember. You can crush in between your fingers. The screw pullout wont be great.
RE: Lateral Buckling Restraint - Steel Members
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Lateral Buckling Restraint - Steel Members
The fastening of Connection B has an added advantage; it tends to prevent local buckling of the flange by pinning it to the AAC at the midpoint of the flange.
I'm not familiar with AAC and if it can be crushed easily by finger pressure as mentioned by Tomfh, both pullout and shear value of the screw may be questionable. This should be assessed before relying on screws for resistance.
BA
RE: Lateral Buckling Restraint - Steel Members
Also for your information the AAC cannot be crushed between your fingers - I have tried....... We also have testing data for the pull-out screw capacity over a number of specimens with values ranging from 0.7kN to 1.4kN.
RE: Lateral Buckling Restraint - Steel Members
BA
RE: Lateral Buckling Restraint - Steel Members
In regards to the stagger, I agree that it is effectively the same thing using 2 screws at the same level and keeping the spacing the same. However there is an element of nice aesthetics of the staggered screws I feel :)
RE: Lateral Buckling Restraint - Steel Members
BA
RE: Lateral Buckling Restraint - Steel Members
Yes it would look bad.
I agree just put in enough normal screws. 1kN per screw will stop a flange buckling.