How to get gtao effect for transparent object

here is the effect I want, I need aomap effect for the floor inside the transparent building, but when I use gtao, the aomap is always wrong, I can’t calculate the ao effect inside the building shell.
Is there a way to achieve this kind of effect, I want to ao to be inside the building shell.

this is the origin mesh, does anybody know how to achieve this effect. any way, not only ao, does anybody know any methods?