How I work on struts.
The main beam is a PT 6x6.
The 2 bars at the top are 3/4" diameter shafts from something.
Short piece of Unistrut to keep the top from sliding up the bars.
The silvery thing near the brackets on the strut is a pipe hanger slightly larger than the strut, bolted to the 6x6.
The jack should be obvious, and is sitting on a piece of 5/16" angle iron, bolted to the 6x6.