A composite access floor panel is disclosed which provides a sheet metal pan filled with a lightweight concrete material. The bottom wall of the pan is contoured so that the thickness of the concrete varies from one location to another. The illustrated panel provides a border of uniform maximum thickness and a central portion of reduced intermediate thickness. In addition, the panel produces concrete oval corner portions and circular side portions spaced in from the centers of the panel sides, both of which provide a uniform minimum thickness. The contours of the panel create a panel in which a substantially uniform amount of deflection results when the panel is supported at its corners and a given load is applied anywhere along the load surface thereof spaced from the panel corners. Shear ties are provided along the interface between the pan and the concrete to cause the pan and concrete to coact in supporting loads applied to such load surface.