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RE: Steel Pan Stairs

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The design info in Julius Blum & Co. is just a reprint of the design
procedure in the NAAMM book mentioned in a previous post.  This design
procedure is very helpful but don't forget to check for the post to
carry the distributed load, as this load cannot be shared between
adjacent post.  Post reinforcing is common place, typically I use 1" Sch
40 or 80 post reinforcing depending on the post height and the design
loading.  Fabrication wise the more post you have the more it cost to
make the rail.  Also you may want to check the flange of the stringer
for the concentrated moment from the post.  If you are using a MC12X10.6
typically a stiffener is required.

Vance P. Grover P.E.
Anderson Iron Works
Rogers, MN
763-428-4531
763-428-8893
 

-----Original Message-----
From: Roger Davis [mailto:rdavis(--nospam--at)sdsarch.com] 
Sent: Tuesday, March 04, 2003 8:08 AM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: Steel Pan Stairs

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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