Wind Girder Section Modulous- How to Calculate?
Wind Girder Section Modulous- How to Calculate?
(OP)
We have been using the guidlines in the API 650 Code for designing our windgirders. However we want to use a shape and size a little different than what is in the code book. Before we do that we want to be sure we are using the correct method for calculating the section modulous. Currently we keep coming up with numbers real close to the figures listed in the code book, but not exactly. Can someone tell me why this might be. Are we perhaps using the wrong dimensions for angle and plate? (I don't see how) or could we be using the wrong method? Right now I am first finding the Moment of inertia about the y-axis then dividing it by the distance from the netural axis to the edge. S= I/c. Please advise, and thanks in advance.





RE: Wind Girder Section Modulous- How to Calculate?
Steve Braune
Tank Industry Consultants
www.tankindustry.com
RE: Wind Girder Section Modulous- How to Calculate?
Anyway, don't worry about it. If you're calculating section modulus correctly, it doesn't matter if API missed it or not, you still need to be correct. Treating a rounded corner as square or vice versa is a reasonable approximate in this case.
I would take the required section modulus equation as being very approximate- try deriving it, and you can get answers that vary by orders of magnitude- so don't get too hung up on the exact values based on it.
RE: Wind Girder Section Modulous- How to Calculate?
RE: Wind Girder Section Modulous- How to Calculate?
The API equation, while based on an idealized wind load pattern, is not approximate. The section modulus requirements for tanks under 200 ft in diameter is intended to limit bending stresses to 15ksi.
Steve Braune
Tank Industry Consultants
www.tankindustry.com
RE: Wind Girder Section Modulous- How to Calculate?