"No cross-section withstands chosen load" Replacing glulam with Ridge Beam in truss (steel) help!

[Mike_the_pip3]

But in the floor plan, you have an interior wall and a staircase almost where the post is. Can't it be moved to become part of the interior wall (or is the floor plan no longer current)?

Nah, initially I had an upstairs with a pool table and bar etc. but I didn't get planning permission because I had to lower the wall height. So now it's an open loft instead and a completely open area. But the workbench will likely be there anyway as it is drawn, so maybe I can have a pillar there.

 

[Dublin]

Nae initially I had an upper floor with a bit of a pool table and bar etc. but couldn't get planning permission because I had to lower the wall height. So now it's open to the ceiling instead and a completely open space. But the workbench will probably still be where it’s planned so maybe I can have a pillar there.

Aren't you going to have a loft over the work area anyway? Now I don't know how many cars you will have there or how much tinkering will be done, but storage is worth its weight in gold even in a large garage.

 

[Mike_the_pip3]

You shouldn’t have loft over the workspace anyway? Now I don't know how many cars you will have there or how much tinkering will be done, but storage is worth its weight in gold even in a large garage.

I’ve realized that a suitable placement for the loft is probably over the doors, easier to mount them in a flat framework. And if I want a lift at the back, that option remains. So now I'm considering whether to mix 2 different trusses. Like below. Frame construction for the first 5m at the doors, then scissor trusses for the rest for ceiling height.

Alternatively, continue the idea with ridge beam/frame beam with rafters. Then build a regular framework over the doors, which can be hung in the trusses to avoid pillars.