In the attached example, is the effective length of the 360UB 0.5span or 0.33span?

[Trippelsewe]

Reading AS4100 5.4.2.3 it seems as though it could be taken as 1/3rd span.

 

[Tomfh]

Use 0.5 span, unless you can be bothered checking that the 530UB is sufficient to act as a restraint for the 360UB segment.

 

[Trippelsewe]

Cheers that makes sense to me. It also makes sense to me that the 530UB would 'cantilever' out past the flange restraint and provide some sort of rotational restraint to the 360UB but I don't know how to verify. So will take the more cautious route.

 

[Tomfh]

Why does the beam splice and change size?

 

[Trippelsewe]

Clearance & install requirements

 

[Smoulder]

5.4.2.3 isn't applicable. Look at 1.3.64 for definition of segment which is from F/P restraint to another F/P. This is half span in your case. 5.4.2.3 only looks at what happens outside that segment not in the middle of it and only applies a factor to the segment length but doesn't set the segment length. 5.6.1.1(b) is what you can use but otherwise same as normal design. You don't assume a constant cross section beam has a restraint mid-segment for no reason.