Garage top slab structure and inner concrete structure cavity membrane thereof

A garage top slab structure comprises an upper layer of top slab, ribbed beams and a lower layer of top slab sequentially from the top down, and inner concrete structure cavity membranes are placed in the closed cavities defined by the upper layer of top slab, the lower layer of top slab and the ribbed beams; each inner concrete structure cavity membrane comprises at least one inner membrane module, and an outer layer of fire-retardant coating and at least one PVC (polyvinyl chloride) fixing frame are arranged on the surface of the inner membrane module; and the inner membrane modules is aare flame-retardant solid polystyrene foam blocks, the density of which is greater than 15Kg/m . The invention also discloses the inner concrete structure cavity membrane, which comprises at least one inner membrane module with the outer layer of fire-retardant coating at the outer surface and at least one PVC fixing frame arranged on the surface of the inner membrane module; and the inner membrane module is the flame-retard