For this sort of "managed destruction", I'd Fracture the floor object with a centered Sphere in the backtground layer to make the fractures more dense toward the middle of the floor, set the Glue Strength to 100% on the Parts Body floor, and use a moving Bullet Collision object which "unglues" the Parts of the floor over time using a Gradient on Distance to Object. Sample scene attached.
In Modeler, create a Floor object and a surrounding Foundation with a ledge to support the edges of the floor as it falls apart:
1. Create unfractured floor
2. Create foundationwith ledge using Boolean subtract, Knife, Extend
3. Create spherical object for background Fracture polygons
4. Set up Fracture using background polys
5. Fracture results
6. Create Bullet Collision object (will be hidden)
7. Rename all layers for clarity using F7
Save the object and send it to Layout.
In Layout, the Floor_Unfractured layer isn't a Bullet object, but is just there to dissolve to 100% when the Floor_Fractured Parts Body starts falling apart. Here's the other Bullet setup:
1. Set the Foundation to Static Body
2. Completely hide the Background Fracture Poly object
3. Set up the Floor_Fractured layer as a Parts Body with a Gradient=>Distance to Object on Glue Strength
4. Parts Body Activation is Start Sleep (until touched by Collision Body)
5. Bullet_Collision layer is Bullet Collision object, moved up so it doesn't touch the Fractured Floor initially
6. Bullet_Collision also set completely hidden
The background fracture polygon layer and the Bullet_Collision layer are completely hidden by using the Object Properties=>Render tab and setting Unseen by Camera, etc. and clearing all the Shadow options.
With Dynamics Disabled, create a motion path for the Collision object to unglue the floor:
7. Dynamics Disabled, move Collision object
Turning on Dynamics, use Front View to determine when the Floor_Fractured body starts falling apart, and Dissolve the Floor_Unfractured object (not a Bullet participant) to show the fractured floor using an Envelope:
8. Dissolve the Floor_Unfractured object (not a Bullet participant)
9. Add some texturing, setup the backdrop:
Enable VPR so the hidden objects and dissolve shows, fine-tune the Parts Body parameters and the Collision object motion: