Process for prestressing by creating a reverse field of stress kept up by the fixation of additional materials

摘要

The invention consists of a method for prestressing structural elements characterised by establishing, in a base element prone to instability, an arbitrary and predetermined stress field of direction opposite that to which the element will be subjected in use (fig. 2). This stress field is maintained, as far as possible or necessary, by solidly attaching suitably sized reinforcing elements of appropriate elastic limit. The complete element is then located in the following situation (fig. 3): - low tension in the additional elements - persistence, in the base element, of a residual tensile field of direction opposite that which will be caused by the principal actions of use. This prestressing is carried out on a special bench (fig. 1) which enables any desired linear stress field to be created. This procedure enables beams to be constructed where it is possible systematically to use high strength materials and to exploit better the capability of lower strength materials by considerably extending their region of admissible stress variation, principally for the parts prone to instability by warping or buckling (fig. 4). IMAGE