I have an idea s to how to do it. But i'm not really sure.

My idea is to have a building and then 
to use Vue to create a version of the building with a piece cut off. 
We can do this using boolean operations. BUILDING minus a terrain or someting that creates a random  surface. I've done it  before so i know it works.

However, when you do boolean, i don't think the boolean shaped object is exported correctly.. So if open in poser, it would n ot look right.

Also, when we do boolean, the original texture map is lost and the object turns grey.

So but anyways,, then what we do is 

1)Open object in poser.. set up your scene. have the original building and the modified one in your scene, but have the modified one totally out of sight. Maybe yTrans -1000 so you sure it won't be seen. Then at the exact time when the building hits the ground, 
use a constant keyframe on both the modified and the original and swap them. The original will be at yTrans -1000, and the modified we will put where the original was landing. 

At the exact time..Start an animation using a group or rocks spreading out in all directions. this will be the debri.  For this we can do it in layers that we can put together in Finalcut( i have it). 
Layer 1 will be poser video of building hitting ground Layer 2 will be an animated smoke video layer. And Layer 3 will be the fast poser animation of debree spreading out in all directions. 

Although i talked here about animating a building hitting the ground. we can eevn do this same kind of swap for say a Tank shooting  a building and creating damage.