Double Cantilevered Canopy
Double Cantilevered Canopy
(OP)
The attached sketch shows a canopy at the entrance of a 4 story building I am working on. Yes, it is architecturally required to look like that. I have done 12' cantilevered canopy in the past, but not 17' cantilever supported by 10' other cantilever. So, I tried the framing shown, put 6' of snow on top and with some W18 beams, the max. deflection under snow is about L( length of cantilever)/300. Compression flanges will be braced along the beams. Please provide your comments and recommendations.






RE: Double Cantilevered Canopy
6 ft of snow sounds like Buffalo.
RE: Double Cantilevered Canopy
Do your results include the deflections due to torsional rotation?
Mike McCann
MMC Engineering
RE: Double Cantilevered Canopy
A few things to check:
Firstly with that moment connection detail you have a long buckling length for the plate at the compression flange so you need to check that it has sufficient buckling capacity.
The uneven configuration will result in an uneven front under dead load so you may want to precamber the most highly loaded cantilever to make up for this. With things like this that people can look along even small deflection can be noticed.
RE: Double Cantilevered Canopy
RE: Double Cantilevered Canopy
I am happy that every note mentioned so far was thought of. Torsional deflection, yes include, slip critical connection will be specified, and for buckling of the bottom plate, thinking of bolting to transverse flange or make it thick enough for the length. The building is in London, ON. Any other notes are welcomed and appreciated.
RE: Double Cantilevered Canopy
I would imagine that the framing will be quite flexible and reaching resonance - or even minor oscillation with fatigue, might be an issue.
RE: Double Cantilevered Canopy
RE: Double Cantilevered Canopy
RE: Double Cantilevered Canopy
RE: Double Cantilevered Canopy