A support structure for a float pan for floating a concrete surface provides an interface between the float pan and a rotating machine. The support structure is characterized by a hub configured for concentric attachment to a rotor, and by trusses that extend radially from the hub, each providing a float pan contact surface and means for attachment to the float pan. Perimetric bracing links the trusses about the perimeter of the support structure. A machine similar to a walk-behind or ride-on trowel but without rotor blades, may incorporate the support structure and operate as a dedicated power flotation machine. Under weight of the machine, the contact surfaces of the trusses conform the float pan to a desired shape or radius of curvature for optimizing a flotation process.