In AECOSimBuildingDesigner V8i SS5 column grids are graphic elements within a cell making them easy to differentiate from plain MicroStation geometry, and are included when publishing i-models. However, in AECOSimBuildingDesigner V8i SS6 column grids are now simple lines, making it difficult to differentiate between Grid lines and normal MicroStation lines. In addition, when an i-model is published the grid geometry doesn't seem to be visible.
In AECOSimBuildingDesigner V8i Ss6 the entire Grid sub-system was revamped in many ways, and one of those differences is that grids are now a collection of geometry and no longer a single cell. But while they are visually identical to "normal" MicroStation geometry, they can be independently selected as Grid element types using MicroStation's Element Information tool:
Where they are identified as Type 106 elements using Building Info and as Grid elements using MicroStation's Element Information tool:
In addition, they are also by default part of a Named Group. The Named Group tool can be used both in the source DGN as well as the i-model, where the Grid elements are selectable en masse through this tool.
Regarding the graphic results when published to an i-model, this is a current limitation of how transient elements are handled by the i-model publish command. Enhancement# 204501 has been filed requesting that Grids have the option to be included as graphic elements during i-model publishing. When output to i-model format, the individual Grid models only display the dimensions (assuming they exist) from the source DGN file and not the grid geometry, although if you zoom out you may see them display by virtue of the HUD technology used in AECOSimBuildingDesigner V8i Ss6.