Dimensions, as we know then from the MicroStation world, are not a supported-feature in Bentley Map. GIS data-types are Points, Lines, and Areas (+ text sub-features); with additional types depending on the storage (multi-point, compound, collections, etc.).
Bentley Map can post and query Features that contain the dimension values for X, Y, Z, Length, Area, Volume, Time, and other measurements – for spatial data that can be mapped, but not a graphic-group of geometry which are dynamically linked to text values representing the size and scope of some element; this is the domain of a CADD tool.
There would certainly be ways to store your Bentley Map GIS feature data in SQL Server Spatial while at the same time using Dimension tools in MicroStation for visualization. Combining multiple applications and application data is sometimes necessary to achieve the desired result.