Abstract: The present invention relates to a support device, more particularly a structural part of a tower construction for mounting a wind turbine, comprising: at least one elongated structural member (102) comprising one or more voids (104) extending over a substantial height of said elongate structural member (102); and a granular core filling material (103) filling at least one of the one or more voids (104) over a substantial height of said elongated structural member (102), wherein the granular filling material (103) is in engagement with the structural member (102) such that it exerts a pressure and provides stiffness against deformation on the surrounding structural member (102). The invention further relates to a tower construction, comprising at least one such support device, as well as methods for improving and constructing such a support device.