Dashed Lines in Moment charts

[civeng80]

Im looking at the AISC Design capacity tables for structural steel Vol 1 (Australia).
Some curves in the effective length vs Design member moment capacity charts are dashed and some are full lines. Yet there is no legend anywhere that shows their meaning.

Can anyone tell me what they mean ?

 

[briancpotter]

The explanation can be found earlier in the chapter (In the American version, at least):

"When the plotted curve is solid, the W-shape for that curve is the lightest cross-section for a given combination of available flexural strength and unbraced length. When the plotted curve is dashed, a lighter W-shape than that for the plotted curve exists."

Brian C Potter

http://simplesupports.wordpress.com

 

[civeng80]

So the dashed lines are for non economical sections?

 

[BadgerPE]

Dashed line would indicate "less" economical sections, not "non" economical. Sometimes headroom dictates what a sections depth can be and then you may be forced to use a section that is dashed.

 

[apsix]

I think that there's a simpler explanation; it's so that you don't lose track of the correct line as they cross over each other.

 

[civeng80]

A bit slack of the authors not putting a note to this affect.