A load bearing panel member having a first portion, a second portion, and an appearance surface portion is formed by injection molding such that the first portion includes a plurality of ribs forming a grid pattern on the first portion and another plurality of ribs extending toward the periphery of the first portion which may be non-orthogonal to each other and to the ribs forming the grid pattern. An internal channel may be formed within each of the non-orthogonal ribs by injecting a gas into the rib during the molding process forming the panel. An appearance surface portion attached to the first portion and second portion of the panel member forms an integral hinge between the first and second portions of the panel member. The panel member may be configured as a floor panel of a vehicle.