Re: SIF values for sustained & occ cases

From: <abdolhossein>
Date: Thu Oct 03 2002 - 12:23:00 EDT

I have seen in B31.3 That earthquake and wind are fatigue loads.you can see this address:
http://www.asme.org/pro_dev/b313.htm
regards

    hossein

Christopher Wright wrote:>I have seen many stress files where sif is ignored for sustained & occ
>(siesmic) cases.

If sif means the stress concentration factor, then it is ignored for seismic and constant loading because peak stresses are only objectionable as a source of fatigue failure. Seismic loading is cyclic but with only a few cycles of high loading and sustained loading is non-cyclic.

Ordinary garden variety Code work(excluding Div 2 and nuclear construction) does not require fatigue analysis because the combination of lower allowable stress and prescribed details provide a sufficient margin against fatigue.

Christopher Wright P.E.    |"They couldn't hit an elephant at
chrisw@skypoint.com        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)

http://www.skypoint.com/~chrisw

Texas Flange - a good source for information on industrial flanges, all they ask is for referrals for designs they help with. 877-610-8924.
www.texasflange.com

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[Non-text portions of this message have been removed] Received on Thu Oct 03 12:23:00 2002