Strange metal plates

[Elkeee]

I have these two metal plates that measure 10 x 25 each in the middle front of my garage floor. One is 33" from the garage door and the other is 73".

They were installed after the slab was poured, someone cut out these sections and added them. I thought they may be some type of heater or something like that but I can not find wiring or breakers for them.

I can tap on them and they are solid, but I don't understand what they could have been for?

I'm from So Cal and have moved my way east landing in Denver, Houston, Omaha, San Antonio, Minneapolis and now West Michigan. I have never seen this before.

i found out through neighbors that a doctor built the house and used the basement for examinations or after hours help of some kind. Other than that nothing else strange.

Have any of you seen these plates before?

Thanks in advance

 

[OccupantRJ]

They look like machinery sole plates, usually precision leveled and grouted in place to support/mount machinery requiring precision leveling or alignment. The doc may have been using some machinery of that nature. That is all I got for you.

 

[Farmall450]

I've seen them in shops for tie downs -- weld on whatever you like.