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RE: OSHA stairs

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As I understand it, the requirement is a strength requirement where the
failure criteria is actual collapse.  The factor of 5 is similiar to that
for hoisting gear.  The normal load anticipated is just that, not
necessarily the design load specified by the building code.  Therefore,
unless the stair serves an assembly area, the actual load is more likely 50
psf (approximately a 300 pound person on alternate treads).

Ed Marshall, PE

> -----Original Message-----
> From:	Harold Sprague [SMTP:harold.sprague(--nospam--at)]
> Sent:	Monday, December 14, 1998 6:26 PM
> To:	'seaint(--nospam--at)'
> Subject:	RE: OSHA stairs
> Bill,
> I consulted our local OSHA safety guru.  OSHA has a web site that can be
> used to pose questions such as this.  I did not go through that, but our
> guru said that paragraph (a) limits the scope and excludes egress stairs.
> To say that the paragraph is ambiguous is an understatement.  You could
> make
> the case that the 1000 pound load is over a 3'-6" square area making the
> 100
> psf case govern.  You could also make the case that paragraph c is headed
> by
> "Stair strength" and take it to ultimate.  You could also claim that any
> of
> these stairs are for emergency egress and technically dodge this bullet.
> (Help me!  I am sounding like a lawyer!)
> As many industrial stairs as I have designed, I have never designed for
> the
> OSHA provision that you have sited.  
> Any other structural industrial types care to wade in? 
> Regards,
> Harold Sprague
> The Neenan Company
> harold.sprague(--nospam--at)
> -----Original Message-----
> From: Bill Sherman [mailto:SHERMANWC(--nospam--at)]
> Sent: Monday, December 14, 1998 1:06 PM
> To: seaint(--nospam--at)
> Subject: OSHA stairs
> For fixed industrial stairs, OSHA requires in paragraph 1910.24-(c):
> "Fixed 
> stairways shall be designed and constructed to carry a load of five times
> the normal live load anticipated but never of less strength than to carry
> safely a moving concentrated load of 1,000 pounds."  UBC requires exit
> stairways to be designed for 100 psf or a concentrated load of 300-pounds.
> If you are installing a stair in an industrial building which could also
> act
> as an exit stairway, how is OSHA to be applied?   
> Are the loads given by OSHA to be applied as "working loads" at basic 
> allowable stress or to be compared to yield or ultimate strengths?  For a
> live load of 100 psf, do they really mean to design the stair for 5 times
> 100 psf?  
> If the stair is not an exit stair, what does "normal live load anticipated
> mean"?  I find the inconsistency in these provisions rather confusing and 
> difficult to apply.