Hi I had went through Dyanmic ansys seminar video 1 - 4, I found maximum span between node points equation given by John Lin and Adolph Molin in Video 4 is L=9.2(D^3t/w)^1/4 at 20:27,
but it given in Video 1 is L=(9.2*D^3t/w)^1/4,
Which one is correct because I dont have referece paper On Mass-Lumping Technique for Seismic Analysis of Piping” - John K. Lin & Adolph T,

another question is mass spacing calculator using equation
L^2 = k^2*(n*pi())^2/(2*pi()f)*(EIG/w)^0.5

I found mass calculator equation result will be slightly larger than John Lin equation, which equation you prefered?

Good catch!
The 9.2 should be outside the radical - the first of your 2 equations.

Mr.Dave ,
I see two conflicting statements for you on factor 9.2 .

1.In this post you state 9.2 should be oustside radical, while as in the post at below link you sugguest it should be within radical sign.


http://65.57.255.42/ubbthreads/ubbthread...=true#Post60407
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The statement is "Maybe you do not have the 9.2 under the radical".

Also in your webinar on Modal Analysis it is inside the radical sign

Please calrify which one the correct equation.

Regards

Good catch. Thank you.
The equation as it appears in our course notes is shown below.
Perhaps I changed it since that presentation but I now show the 9.2 outside the radical in that Modal Analysis webinar - also shown below.

The 9.2 is supposed to be outside the radical.

Thanks Dave for your reply,
Best Regards,
Limin

Thanks for your reply and providing the correct equation.

Regards