Friday, January 4, 2008

Re: Handrail Loads vs Short Term

Harold -
  Regarding the handrail/guardrail ASD increase, this is valid only when you use the railing design loads prescribed by the IBC.

  Is this correct? Or can you use any concentrated/uniform load and still apply the one-third allowable stress increase? <I don't have the latest/greatest IBC with me. Hence, my question>.

Thanks,
Charlie Canitz  


-----Original Message-----
From: Harold Sprague <spraguehope@hotmail.com>
To: seaint@seaint.org
Sent: Fri, 4 Jan 2008 3:13 pm
Subject: RE: Handrail Loads vs Short Term

Dr. Hamida,
 
The allowable stress increase has been in the process of getting dumped for several years. 
 
Please look at the 2006 IBC
1605.3.1.1 Stress increases. Increases in allowable stresses specified in the appropriate material chapter or the referenced standards shall not be used with the load combinations of Section 1605.3.1, except that a duration of load increase shall be permitted in accordance with Chapter 23.
1605.3.2 Alternative basic load combinations. In lieu of the basic load combinations specified in Section 1605.3.1, structures and portions thereof shall be permitted to be designed for the most critical effects resulting from the following combinations. When using these alternative basic load combinations that include wind or seismic loads, allowable stresses are permitted to be increased or load combinations reduced where permitted by the material chapter of this code or the referenced standards.....
 
There are only a few applications that allow an allowable stress increase in the current IBC.  They are allowed:
1.  In handrails (1607.7.1.3) as previously mentioned. 
2.  Wood - 2306.2 Wind provisions for walls.  2306.2.1 Wall stud bending stress increase.
 
There are even fewer provisions for allowable stress increase in the ASCE 7-05. 

Regards,
Harold Sprague



From: y.hamida@scs-net.org
To: seaint@seaint.org
Subject: Re: Handrail Loads vs Short Term
Date: Fri, 4 Jan 2008 11:17:31 -0800

If the design for seismic or wind you can use 1.33
 
 Dr.hamida
----- Original Message -----
From: Rick
Sent: Friday, January 04, 2008 10:37 AM
Subject: Handrail Loads vs Short Term

I've never used a 1.33 increase on handrail components, but have one that doesnt calc out without it. Can handrail loads be considered short term?
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