The layout grid framing is hanging on screws that hopefully are not drywall type and are ones that have good tensile/shear strength. A good step if using drywall screws, a part of your "bracing" should be to add 10-12" long 2x2 or 2x4 blocks under the 2x4 perimeter and center girders on each leg to provide a direct bearing surface. Yours is not a lightweight girder system and you will likely be crawling on top of this island type layout at some point to reach ceiling lights, etc.
