Lighting Pole Damper

[BrianDH]

Has anyone called out a type of damper to reduce the 1st and 2nd mode vibration of a tall (130') lighting pole? I did some research myself, and there are commonly 2 types available - canister type and a serpentine type (for insert inside the pole). But I have a hard time finding a supplier to speak to. Anyone has any advices or experience to share with us?

Thanks!

 

[JAE]

Bump

Apparently not too many deal with this.

I've done some 144 ft. poles on drilled piers - but no dampers.

Is this for seismic reasons or wind?

 

[BrianDH]

This is for wind. Most likely the vibration is caused by vortex shedding (for 15" round pole at the top with a 0.6 sec 2nd mode period, the critical wind speed is just over 7 mph).

I think there is some flaw in the design for this pole. The 2nd mode frequency seems a bit too low to me. But stiffening up the pole is probably not even an option due to the potential visual impact.

 

[hokie66]

I googled "tuned mass damper for lighting poles", and found this paper. It or the contained references may help.

http://www.cooperlighting.com/common/brands/literature/McGraw-Edison/ACF090398 Poles White Paper.pdf