There are five supports for the carport. All made of steel tubing.
One is a little bit worn. Neighbor suggest adding pressure treated post 4in x4in.x 8ft. Tried looking for a floor flange to fit on the cement floor. Unable to locate. On top it appears to be some kind of T square mounting bracket that accepts the post at the top.
What do they call this hardware?

T bracket. Go to lumber Dept at HD or Lowe's and you will find them. Simpson brand.

Thanks

thanks
Think I mislead you. The top is a T Bracket. The bottom is a base or column support. They are 3 1/2" square and come in a number of varieties. Same place.