A panel assembly includes at least one reinforcing assembly made of a high strength material having a low yield to tensile strength ratio for energy absorption and reduced weight and profile. The panel assembly may be light-weight with a low profile to minimize protrusion into an opening or compartment enclosed by the panel. The panel assembly may be a floor panel assembly for a vehicle floor. The reinforcing assembly may traverse the panel such that the reinforcing assembly extends laterally, e.g., cross-vehicle, relative to the longitudinal axis of the vehicle body. A method of making the panel assembly may include forming the reinforcing assembly by joining a plurality of metal channel members in a nested arrangement with a plurality of welds to provide a structural assembly with good bending resistance loads imposed on the panel assembly including knee loads. The channel members may be made of a dual phase steel.