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
E04C3/22—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 built-up by elements jointed in line
System of concrete structures having panel and column portions with rigid member and end of panel portion of one structure received in slot of column portion of adjacent structure