Abstract: A profiled deck is roll-formed from a steel sheet to define at least one pair of crests, a stiffener upstanding from the surface of each crest, a trough positioned between the or each pair of crests, and inclined webs extending between the sides of the trough and the neighbouring sides of the crests. The boundary between each web and crest defines a corner which has a smooth curvilinear profile and the elemental compression width of each crest is no more than four times the elemental compression width of the respective stiffener. Furthermore, the radius of each curvilinear corner is not less than 33 mm.