E04C3/00—Structural elongated elements designed for load-supporting
E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
E04C3/20—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of concrete or other stone-like material, e.g. with reinforcements or tensioning members
E04C3/26—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of concrete or other stone-like material, e.g. with reinforcements or tensioning members prestressed
B—PERFORMING OPERATIONS; TRANSPORTING
B28—WORKING CEMENT, CLAY, OR STONE
B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
B28B21/00—Methods or machines specially adapted for the production of tubular articles
B28B21/56—Methods or machines specially adapted for the production of tubular articles incorporating reinforcements or inserts
B28B21/68—Methods or machines specially adapted for the production of tubular articles incorporating reinforcements or inserts and applying centrifugal forces
E—FIXED CONSTRUCTIONS
E04—BUILDING
E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
E04C5/08—Members specially adapted to be used in prestressed constructions