Abstract: A deck comprises a plurality of elongate members (11), such as aluminum extrusions, which each comprise a top flange (12) and a bottom flange (13) interconnected by a web (14) and which are laid side-by-side in abutment and intercoupled, either by integrally shaped parts of the webs or by separate components, such as bars (16), to produce a cellular body with a closed top surface formed by the top flanges (12), a closed bottom surface formed by the bottom flanges (13) and internal bracing. A plurality of tie rods (17) extend transversely of the members (11) by way of bores in the webs (14) and, in conjunction with nuts (18), clamp the members together to form the body into a rigid structure which is stressed in both longitudinal and transverse directions.