Base plates
Base plates are a flat metal plate with holes in it that is welded to the bottom of a fence and then used to bolt the fence to the floor.
In some cases, base plates can be welded to the side of a post to allow the fence to be side mounted, and sometimes, separate base plates are bolted to posts, but this is a weaker installation method and not recommended for every application.
There are many different kinds of base plates that can be used to install most types of fencing on an existing concrete slab or beam, and on many other surfaces. They are also available in a variety of thicknesses and sizes, so there are many options you can choose from, based on the design of your fence system.