metal bands 4 forming the linking stirrups between the longitudinal flat irons 3 3 u2032 can be formed easily for example in order to sustain the shearing loads as efficiently as possible besides taking into account the relatively small thickness of the flat irons used the said flat irons can be delivered to the manufacturing workshop of the armourings in the form of reels whereas the flat irons are simply unwound and straightened on site according to the requirements besides a reinforcing cage according to the invention is manufactured more easily than a conventional cage indeed in the conventional technique there are only quasi punctual contacts between the round bars and the stirrups the links between the different elements to form an integral assembly are made either by wire ties or point by point by arc welding and these operations are rather long and costly in the case of the invention conversely the different elements of the reinforcement are all composed of flat bands whose opposite faces are applied on one another and can be welded easily for example with pliers the realisation of a reinforcing cage is therefore easier and calls for less specialised staff it is thus possible to reduce not only the quantity of concrete to use but also the manufacturing cost of the reinforcing cage and the global cost of a prefabricated element according to the invention can thus be reduced significantly the advantages supplied by the invention compensate therefore easily the price increase of the rods.