- A composite floor structure comprising a plurality of prefabricated concrete slabs (Dc, Dp, Dr) forming a floor supported at two ends by two steel edge profiles (Pr) and, between the latter, by a plurality of steel joists, the edge profiles (Pr) and the joists being parallel and regularly spaced apart, characterised in that the slabs (Dc, Dp, Dr) comprise first slabs (Dc), called connected slabs, second slabs (Dp), called supported slabs, and third slabs (Dr), called edge slabs, which are arranged in an arrangement of rows and columns, the rows being perpendicular to the joists, and in that: - each column along an edge profile (Pr), called edge column (Clr), comprises alternating connected slabs (Dc) and edge slabs (Dr), each of the connected and edge slabs (Dc, Dr) bearing by a first edge on an edge profile (Pr) to which it is connected by connecting means, each connected slab (Dc) also bearing by a second edge, opposite the first edge, on the following joist, to which it is also connected by connecting means; - the rows each comprise, from an edge profile (Pr), an edge slab (Dr) or a connected slab (Dc), followed by alternating connected slabs (Dc) and supported slabs (Dp), respectively alternating supported slabs (Dp) and connected slabs (Dc), each connected slab (Dc) of said alternating slabs (Dc, Dp) bearing on a pair of joists to which it is connected by connecting means, each supported slab (Dp) bearing, by two edges, on two corresponding edges of two adjacent connected slabs (Dc), which are cantilevered with respect to the respective joist, the slab bearing on the other edge profile (Pr), and connected thereto by connecting means, being an edge slab (Dr) or a connected slab (Dc); and - along each edge profile (Pr) and along each joist, each connected or edge slab (Dc, Dr) is in contact with the adjacent connected or edge slab(s) (Dc, Dr) in the direction parallel to the joists. - each column along an edge profile (Pr), called edge column (Clr), comprises alternating connected slabs (Dc) and edge slabs (Dr), each of the connected and edge slabs (Dc, Dr) bearing by a first edge on an edge profile (Pr) to which it is connected by connecting means, each connected slab (Dc) also bearing by a second edge, opposite the first edge, on the following joist, to which it is also connected by connecting means; - the rows each comprise, from an edge profile (Pr), an edge slab (Dr) or a connected slab (Dc), followed by alternating connected slabs (Dc) and supported slabs (Dp), respectively alternating supported slabs (Dp) and connected slabs (Dc), each connected slab (Dc) of said alternating slabs (Dc, Dp) bearing on a pair of joists to which it is connected by connecting means, each supported slab (Dp) bearing, by two edges, on two corresponding edges of two adjacent connected slabs (Dc), which are cantilevered with respect to the respective joist, the slab bearing on the other edge profile (Pr), and connected thereto by connecting means, being an edge slab (Dr) or a connected slab (Dc); and - along each edge profile (Pr) and along each joist, each connected or edge slab (Dc, Dr) is in contact with the adjacent connected or edge slab(s) (Dc, Dr) in the direction parallel to the joists.