Thanks for your post!
There are a couple of ways you can do this:
1. Easiest & Fastest:
Create a material called 350 UC Column or as you like, associate it with a column and then add a price to it. Though it won't look like a typical Universal Column, it will quantify as you need in the takeoff and it will be nice and fast to model.
2. Looks the Same
You can simply use the SketchUp rotate tool to rotate a 350 UC Beam to stand horizontally, you will just need to create the material in the Beam tool. This means it will look the same and quantify as you need.
3. Looks most accurate
You can draw the column to look as you like using the SketchUp tools and then create it into a BIM component using the BIM tool (add specs, pricing, contacts etc.) and it will quantify in your takeoff. Then you can save it as a component (as per this forum post: https://forums.sketchup.com/t/component-saving/23003
) and use it again and again.
Currently there isn't a structural steel column option in the Post/Column tool just yet, but it's something we can add on the request list and look at in the future.
Hope this helps!