FIELD: building materials. SUBSTANCE: beam includes compressed and stretched belts connected by connecting members. The latter are made of discrete or combined over beam length shells and/or folds oriented at angle to longitudinal axis of beam and secured to, at least, compressed belt over contact contour of shells or folds. Distance between their extreme points in level of contact with compressed belt in projection on lateral plane is, at least, not less than between corresponding points in level of contactor of shells or folds with stretched belt in projection on same plane. Versions of beam design are provided. EFFECT: higher efficiency. 20 cl, 37 dwg
