What is the actual name of those rods, which are hung from the ceiling, used to support walkways or overhead catwalks ?
Note: I'm not talking about curtain or shower rods, I'm talking about the kind capable of handling a huge load.
I believe they're called tie rods - https://en.wikipedia.org/wiki/Tie_rod
There's a famous case of a massive engineering failure involving walkways held up by steel rods - the 1981 Hyatt Regency disaster:
The walkways collapsed onto the people below, and it turned out to be because the steel rods holding up the walkway had not been attached to the walkways in the precise way detailed in the plans. This deviation introduced a terrible structural weakness which led to the collapse.
In that Wikipedia article, the rods are variously referred to as "tie rods", "steel rods" or "steel tie rods". If we use this as evidence, I'd say that the name of the component is a "tie rod", and the ones used in this incident were made of steel, hence "steel tie rods".