A rotational element, to be braked, is provided on two opposite sides with braking discs. Each of the braking discs is constituted by an odd number of at least three segments. There are elements rigidly joining the segments together, elements rigidly fixing the segments to the rotational element and elements rigidly joining together the discs arranged on opposite sides of the rotational element. The rotational element includes a hub and a rim, joined by a web. In a preferred embodiment, the web includes a first radial region of greater rigidity located closer to the hub and a second radial region of lesser rigidity located closer to the rim. In these regions there are provided respective series of through apertures. The braking discs are secured to the rotational element in correspondence with the more rigid radial region. The rotational element can be provided as a central portion of a larger structure, or as an actual wheel, such as a railway wheel.