METHOD OF MANUFACTURING A GIRDER WITH A PREFLEXED OR PRESTRESSED AND/OR AT THE SAME TIME PREFLEXED AND PRESTRESSED RIGID REINFORCEMENT

摘要

1. Process for the production of a prestressed beam, either pre-flexed or pre-drawn, or both pre-drawn and pre-flexed, and the beam made up of at least one rigid metal truss, usually made by rolling and/or welding which has been subjected before coating to pre-flexing or pre-traction, or to a combination of pre-traction and pre-flexing to achieve deformation in the same sense as that it would be submitted to by the action of the service loads, then coating with concrete at least one part of the tensioned fibers of such truss thus pre-flexed or pre-drawn, or both pre-drawn and pre-flexed, and the truss which, when released after the concrete has set, cannot resume its original shape under the action of its elasticity, characterized by the fact that, previously, the rigid metal truss is in addition subjected to at least one elastification loading by means of forces determined as to value and position in such a way that the diagram of moments or nomal stresses generated is close to the envelope of all moments, and normal stresses to be reached under service loads, in such a way that the internal stresses in the rigid metal truss arising in the course of its manufacture are almost entirely eliminated.