Flexible Diaphragm for Sun Shade Shelter

[300redbeard]

I have a background in designing PEB's and mini storage light gauge steel structures.

In my experience I have used either diagonal rods or diagonal flat strap bracing for my flexible diaphragms when using steel roof decking that is NOT shear rated: typical standing seam roof.

I'm reviewing sunshade structures that are both flat and hip roof design. They have NON shear rated metal roof decking (no flexible roof diaphragm). The columns are cantilevered column design. The EOR is saying the bolted connections from the column top to beams are moment connections and make up the flexible roof diaphragm and that the shear rated metal roof is not necessary.

Can I get some guidance on this matter?

Thanks

 

[msquared48]

What I hear the EOR saying is that the building is a pole building design, but with at least two moment frames in each direction.

this is so, considering the possibie smaller size of the structure (you did not mention the size) and some contribution of the metal decking laterally, then a flexible diaphragm is not really needed. Technically, I would have to agree with him.

Mike McCann
MMC Engineering

 

[300redbeard]

The flat roof is 20'x40' and the hip design is 15'x30'

 

[RFreund]

I think I would have to agree that the the diaphragm is not need as long as the beams are designed for the unbraced length. Also if any wall elements (i.e. light gauge wall studs) frame in to the underside of the beams then they would have to carry the wind load in weak axis bending. Same for the gable roof I suppose.

EIT