Removal of "top flange and web" from beam with small truss above

[WoodDesignCat]

My company wants to re-orientate the vacuum lift rail shown in the attached picture, where we'd have to cut off the sloped members above the main steel beam, which acts as the rail. I'm planning on checking the remaining section for stiffness and strength and specifying minimum support lengths, and possibly additional reinforcement to be added. But my question is, is there a purpose of the top flange and webs beyond adding some extra stiffness and strength to this beam? I'm having trouble imagining it adds much with the small 2 inch, unbraced, rectangular sections above the ~12in x 8in I-beam section. Am I misunderstanding their purpose? Also I'm not used to seeing vertical web members in a truss, which makes me question further.

 

[KootK]

1) It is possible that the HSS overbuild stuff is only there to allow the lift beams to pull double duty and support the roof purlins above. That said, these frames seem very close to the adjacent pitched rafters for them to be there for this purpose.

2) It is within the realm of possibility that the designer of the lift beams used the HSS overbuild, and it's connection to the roof purlins, as a way to brace the lift beams against lateral torsional buckling (LTB). When it comes time to check the lift beams for lateral torsional buckling in the new orientation, just be sure that you're assumptions regarding top flange bracing and torsional bracing of the beams are reasonable given the reality of the physical situation.

If I were using the HSS things for LTB bracing, I probably would have detailed some partial height stiffeners beneath the verticals. That said, it usually doesn't take a whole lot to effectively brace a thing.

What do you know about the connection between the top rail of the overbuild and the underside of the roof purlins?

 

[dold]

Doesn't look like there's any connection to the purlins.

I suspect:
Manufacturer of the trolley system has a maximum beam flange width/thickness that the trolley wheels / trucks can accommodate. If you look closely you can see that the trolley wheel / truck assembly is almost completely 'full' of beam flange.
And they couldn't go with a deeper beam due to the roof height at either end of the beam.
So, they added this quasi-truss thing to the top to increase stiffness as they could not use a heavier or deeper section.

Looks like there are angles welded to the top flanges between the two beams of the gantry, presumably to fight LTB...

Probably unrelated to anything, but there's also a splice plate at midspan of the beam on the web.

But now that I see the splice plate, that makes me wonder if they were unable to make a splice on the flanges as that would interrupt the travel of the trolley? There almost seems to be a gap where the flanges would be spliced. And so they rely on the web splice plate to take the resulting tension in the bottom 'chord' (W section)? Seems kindof half baked... Maybe they didn't know that full pen welds are a thing?

 

[KootK]

Now that I've heard him tell it, I agree that dold's narrative sounds most plausible. That said, I very much doubt the efficacy of the solution for many of the same reasons that OP mentioned. Unbraced, undersized, untrussed...

 

[BAretired]

If the splice in the 12"x8" I-Beam section is just a web plate, it does not develop the flanges of the beam. Removal of the sloping members above would reduce the moment resistance to near zero unless a full strength splice is provided in the I-Beam.

How is the member to be re-oriented?