Performance of a rafter arch considering prestressing

The study of the influence of prestressing steel structural elements on their overall stress-strain state is not fully reflected in the literature, although its use allows stress to be redistributed from the most stressed elements and cross-sections to less stressed ones. This is especially true for span structures of buildings of various purposes, in which significant forces and deformations occur in the design cross-sections of individual elements. When creating preliminary forces and deformations, the internal forces in the structural elements and sections have the opposite sign compared to the sign under the action of external loads. Prestressing forces are created by using simple mechanisms employing bolt tension, which provides significant material savings at relatively low costs for the prestressing structure itself. In general, the essence of the prestressing method for steel structures is that, through insignificant one-time costs of material and labor, the necessary initial forces and deformations are created in the structure, which during operation allow the main structural elements to continue elastic operation. The article presents the results of a theoretical and experimental study of the influence of arch tie prestressing on the redistribution of stresses in the design cross-sections of its chords. Moreover, the analysis of the stress state of the perforated compressed-bent arch chord was carried out by comparing theoretical and experimental stresses in its characteristic sections near the support nodes, the tie attachment nodes, the apex node, and the points of application of concentrated forces. Theoretical stresses were calculated using the design standards method, and experimental stresses were measured using strain gauge equipment. Comparison of stresses in characteristic cross-sections was carried out under the action of external load without prestressing; taking into account the influence of tie rod prestressing; and under the action of external load taking into account prestressing.