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Re: Light Pole Failure

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Steve,

	My first thought was that you had a vortex shedding/vibration/fatigue
problem but I did some quick calculations and ruled that out in my own
mind (This doesn't mean you should forget about this mechanism).  I'm no
welding expert; but I suspect you have a material spec problem or a
welding procedure problem.  Perhaps the material is too thin to be
welded with the procedures used.  This gives you serious cause for
concern for any other standards purchased at the same time.

				Regards,

				H. Daryl Richardson

Steve Hiner wrote:
>
> Two light pole failures in the last three years ... doesn't sound like many,
> but the failure mechanism is of some concern.
>
> Central California - 75 mph design wind speed
> Some strong winds occurred several months back (40-50 mph gusts)
> (Poles did not fail/drop during those storms)
>
> 30' tall poles with light standard (about 3 years old)
> 5" square steel tubes, 1/8" thickness (material spec - not sure)
> 12" +/- x 1" thick square base plate w/ 4 anchor bolts
> The base plates have 5" square holes such that the tube slides within the
> base plate thickness
> Fillet welds - all around (3/16" or 1/4"? +/-) at top of base plate to tube
> AND at bottom edge of tube to 5" square slotted edge of base plate.
>
> Failure has occurred in the steel tube just above the fillet weld between
> the top of base plate and the tube section.
>
> Would be interested to hear some opinions or from those who may have
> experience with similar failures.
>
> You can also contact me personally at shiner(--nospam--at)folsom.ca.us
>
> Regards,
> Steven T. Hiner, SE
>
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