Vibration Analysis in canopy

[tdm01]

I'm in the process of designing open entrance canopy that has a cantilever of approx. 15'-0". It's been designed for the gravity and wind loads as per ASCE-7, however, I'm a little concerned about the vibration at the end of the cantilever under the wind loading. It's in a Hurricane prone region. I've done some research, but can't seem to find anything. Any advice or references on the subject would be appreciated.

 

[ishvaaag]

There is a point where structural design for wind and aerodynamics merge. Some are proposing doing so for some signs over highways. Since your structure is of moderate size it could be practical to design it for plane lift forces, say 450 kg/m2 and then make the anchors stand say, 20000 cycles.

 

[Ron]

I've designed hundreds of canopies for high wind loads and do not consider this to be a significant issue. Yes, fluttering can occur; however, due to the geometry of most canopies and the numerous unknowns by which to try and predict the orientation, oscillation, frequency and magnitude of such vibrations, it is a shot in the dark.

Is your canopy a true cantilever or does it have hanger rods?

 

[tdm01]

Thaks for the input. It is a true cantilever.

 

[FeX32]

If you have reason to believe that the wind speed exceeds that of the flutter speed and it is a "critical" criterion then you could design a tuned vibration absorber(TVA) for it.
Assuming it is only the first mode you want to suppress using a small absorber mass ie. mass ratio less then about 0.01 then you need to tune the stiffness of the TVA to equal that of the natural freq. of the canopy.

TVA's are used in all recent major high-rise bldg's


Fe

 

[bbcboston]

I have a similiar canopy over an entrance door. It has 3 supports (one in the middle and 2 at each end). The end supports are hangers. I usually use the ASCE -7 open structure figures for wind loads, but am thinking of using the roof overhang figures. Off topic, but curious what you used and think. Thanks