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Tube shape LRFD design

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I am designing a HSS18x6x5/16 beam with combined bending and torsion,
simple span.  It spans 30 ft and is unbraced the full length.  I am
looking at AISC Specification for the Design of Steel Hollow Structural
Sections, Sect. 5.1 (pg. 7).  b/t ratio is less than lambda(p) for the
strong axis and greater than lambda(r) for the weak axis.  I have reduced
the section modulus of the weak section as detailed in the specification.
 

At the bottom of the page it has a paragraph dealing with unbraced
length. It states Lb (unbraced length) is not limited for HSS shapes.
designed by elastic analysis and is limited by some equations for plastic
analysis.  Since I have a simple span beam I have an elastic analysis. 
Am I reading this right, there is not unbraced length limit for this HSS
shape?  This shape is designed for Mp in the strong axis and Mn in the
weak axis?

Thanks.

Rich

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