I have 2 big trellices like that made from 2 inch galvanised pipes and drilling rods( from oil rigs).
They are welded and strong but be carefull if you weld galvanised steel because the yellow ,heavy smoke its deadly.
Its heavy,no big deal,i weld it all the time without a respirator ,but you dont want to be lower than the weld or otther person or animal that could fall on it and breathe it .Kills instantly.
EDIT,the 2 inch pipes my trellices are made are thick steel ,also from drilling rigs and i dont think they were galvanised.
Basically i have 80% of my trellices made from oil rig pipes and full steel rods but inbetween the pipes and rods i have galvanised pipe .
If you use galvanised pipe and your a novice welder,its safer to use bolts than welding it.