Elements of resource assessment of steel beams prestressted web

The article presents possible ways to determine service life of steel single-span beams with prestressed web. The authors implement the method for searching coefficients of optimal distribution of material over the cross section of a symmetrical, monometallic steel I-beam. Basing on structures theory the study determines the maximum permissible moments of external loads for ordinary and prestressed beams. It formulates analytical expressions characterizing the first and second limit states of prestressed beams and establishes the resource of their bearing capacity. As a result of performed analysis, analytical dependences of prestressed beams stiffness are determined and structures resource is established according to this criterion. The study determines height of beams and its change with span variations and actual uniformly distributed load. Resource height of prestressed beams is established in comparison with height of conventional bending structures. Load-bearing capacity of beams with prestressed web is 1,8 times higher than the corresponding capacity of conventional beam. and their resource is 180 %. Deflections of prestressed beams are 77,3 % less than deflections of traditional beams and stiffness resource is 1,29. Height of conventional beam is 1,847 times higher than height of prestressed structure. Service life of prestressed beam is 187%.