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# RE: Steel Pan Stairs

• To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
• Subject: RE: Steel Pan Stairs
• From: Roger Davis <rdavis(--nospam--at)sdsarch.com>
• Date: Tue, 4 Mar 2003 08:07:57 -0600

```Julius Blum & Co. manufactures components for railing systems.  They
include a section on railing design in their catalog.  They include a graph
to show what percentage of applied load can be assumed to be carried by
adjacent posts under different circumstances.  A summary statement in the
literature that gives you an idea of how the chart can help is as follows:
"When posts and rails are of identical material and section and post
spacing is between 3 and 6 feet while post height is between 30 and 42
inches, load distribution is fairly uniform.  In this situation, the
greatest proportion of a concentrated load carried by any post can be
estimated as follows:
End posts:
2 span railing		Pf = 0.85
3 or more span railing	Pf = 0.82
Intermediate posts:
2 span railing		Pf = 0.65
3 or more span railing	Pf = 0.60
They also talk about reinforcing pipe internally.

Incidentally, even though a lot of people believe that 1 1/4" pipe is the
largest you can use to meet the ADAAG maximum pipe diameter of 1 1/2", that
is not true.  The Department of Justice issued a rare written determination
that the 1 1/2" was a nominal number and that 1 1/2" pipe with an actual
outside diameter of 1.9" satisfied ADAAG requirements.

Roger C. Davis
Architect
SDS Architects, Inc.

-----Original Message-----
From:	Rand Holtham, Sigma Engineers [SMTP:rand(--nospam--at)sigmaengineers.com]
Sent:	Monday, March 03, 2003 5:21 PM
To:	seaint(--nospam--at)seaint.org
Subject:	Steel Pan Stairs

<< File: ATT00003.htm >> Does anyone have any insight on steel pan stair
design. I have trouble with an analytical design for such a structure. For
instance an 1 1/4" diameter post supporting a handrail/guardrail with the
prescribed load of 100plf vert. and 50plf lateral at 36" centers can have a
cantilevered load of somewhere between 150lbs to 260lbs at a height of 42"
(at the landing). This will cause a load well in excess of the strength of
the pipe. Then there's the question of how you resolve the weak axis
bending in the stringer. It seems to me that from most stair systems I've
seen that there more empirically designed than analytically design.

Any input would greatly be appreciated.

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