Re: SIF values for sustained & occ cases

From: <Christopher>
Date: Fri Sep 27 2002 - 23:18:00 EDT

>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 <a href="/group/PipingDesign/post?postID=3q7jBbT7y5aU9I8qnOEqUWH2mJY8bszlk6zDV2wKZQIjGXAvgNAByscwxwskvwxG7q7Dx506IakX">chrisw@skypoint.com</a> | this distance" (last words of Gen.

___________________________| John Sedgwick, Spotsylvania 1864)

<a href="http://www.skypoint.com/~chrisw">http://www.skypoint.com/~chrisw</a> Received on Fri Sep 27 23:18:00 2002