That metal is *not* thick at all, it’s looking like only 1/4 for both the beam and the plate. In my experience sticking doesn’t produce a lot of sparks, migging does send sparks flying though.Gravity, there would be no stress on the bolts unless there was lateral shifting. It's more work and more expensive to drill and bolt it but not everyone has access to a welder capable of fusing that thickness of steel or wants to do that in their house because lots of flying balls of liquid metal