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Re: Light Pole Failure

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Steve,

If I were stuck with using the original HSS (thin-walled) section, I would
seriously look at using 3/16 or 1/4" through plate tapered stiffeners (1
full + 2 halves), located on X-Y planes, and I still like the 18 to 24"
height !  And with all this additional material interface I'd keep the weld
sizes to a minimum at the tube.

Hey, after writing that, my gut still feels OK ...

As a footnote to your OOPS -
On the contrary, let's keep this brainstorming session "in the open" !  I've
been reading some excellent responses and suggestions from this vast
collective (list) of superior knowledge !
Besides, if 'my gut' makes a mistake or overlooks something - maybe someone
will kindly slip me a verbal "antacid".

Best Regards,

John Hilzman, CEO
STEEL TECH INC.

----- Original Message -----
From: "Steve Hiner" <shiner(--nospam--at)folsom.ca.us>
To: <jhilzman(--nospam--at)steel-tech-na.com>
Sent: Friday, February 08, 2002 3:47 PM
Subject: RE: Light Pole Failure


> Oops, this was meant to go to you John, rather than the list server
>
> --------------------------------------------------------------------------
> Your following message has been delivered to the list
>   seaint(--nospam--at)seaint.org at 14:43:36 on 8 Feb 2002.
> --------------------------------------------------------------------------
>
>
> John,
>
> Thank you for the thoughtful response.
>
> One question ... would the 4 vertical stiffeners referred to below be
welded
> at the center of each 5" face of the pole.  If so, do you see any problems
> with the bending that would be placed on the tube thickness?  Or is that
why
> the stiffeners are recommended to the 18 - 24" height?  Gut feeling of
> course.
>
> Regards,
> Steve
>
>
>
>
> -----Original Message-----
> From: Steel Tech N.A. Inc. [mailto:jhilzman(--nospam--at)steel-tech-na.com]
> Sent: Thursday, February 07, 2002 7:53 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: Light Pole Failure
>
>
> Dear Steve,
>
> I'd place money on this one (but, not a stamp - that one is on you) :
>
> First, I think that a 1/8" wall thickness is too light for the expected
> service environment and height - suggest 3/16 or 1/4". As an alternate,
> consider
> 1/4" for the lower 1/3, then 3/16" for the upper 2/3, but this requires
> expensive welding, not worth the extra material costs.
>
> Second, the pole needs to have at least four (4) tapered vertical
stiffeners
> (3/8") approx. 18 - 24" tall (fully welded) - an alternate would be to use
> through plates (1 full + 2 halves). No need to cut, insert and weld the
pole
> into the base plate zone.
>
> Thirdly, if first and second insights seem like overkill - then I'd look
> long and hard at the use of such a large weld to such a relatively thin
wall
> shell.  All that heat could be changing some of the chemical composition,
> maybe inducing some brittleness.
>
> Last but not least is the 'shape' factor. I know that rectangular or
square
> shapes have a special visual appeal, but from an aerodynamic standpoint
> during moderate to high wind conditions, I bet that pole is going through
> some weird oscillations (fix base + FREE head) and possibly creating some
> stress cracks at points of high and/or unbalanced shear zones. Maybe,
round
> sections should be considered a better choice.
>
> Now the disclaimer - did not perform even one calculation - everything
above
> is based on pure, old-fashion ( and yes - that means age), gut feelings,
> based on many years of experience and hard-knocks, and a dash of dare !
My
> attorney wants me to reconsider this legal disclaimer, but it's going to
> cost me - besides I think most understand it better than that attorney
talk.
>
> Have a great day Steve, and let me know what your hardwork and final
> conclusions reveal !
>
> John Hilzman, CEO
> STEEL TECH INC.
> ----- Original Message -----
> From: "Steve Hiner" <shiner(--nospam--at)folsom.ca.us>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Thursday, February 07, 2002 5:34 PM
> Subject: Light Pole Failure
>
>
> > 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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