Abstract: A lightweight, high-strength load bearing floor structure includes a core made of expanded polyolefin foam material and a layer of material bonded or otherwise attached to an upper surface and a lower surface of the core to sandwich the core. The layer of material is made of a lightweight, high-strength material, such as a metallic material, or the like. An upper panel and lower panel may be mounted to the metallic layers, and a decorative covering may be applied to one of the upper and lower panels. The core and layers of material form a high modulus, high stiffness, lightweight composite structure suitable for load bearing floor applications, or the like.