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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?



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