If you extract the data files associated with FO4, you can find a number of pier pieces. In the vicinity mentioned, there are a number of static collections (SCOL) used. The model file (NIF) that closely represents the piece in your photograph is PierMid01.nif. This file appears to have dimensions are that of a standard floor tile. You’ll need nifskope to open these files. Of course, these will be in the Creation Kit as well.PierMid01.rar