The production of the anchor heads in the prior art type of construction of high quality steel is materially expensive, and in addition very time consuming in the processing. Moreover it has been observed that the load distribution is uneven in the area of transition from the wedge to the conical part of the bore of the anchor head. This has to do with the fact that the conical form of the bipartite or tripartite clamp, whose parts have moreover longitudinal slots, cannot be produced, with respect to the conical part of the bore of the anchor head, in such a way that the fitting surfaces between the wedge and the conical part of the bore of the anchor head correspond exactly in the stressed state of the prestressing element. This is due to the fact that the wedge is pulled into the conical part of the bore of the anchor head by some millimeters during wedging of the prestressing element, achieving clamping of the prestressing element.
A clear load peak arises at the end of smaller diameter of the frustoconical wedge located on the interior of the anchor head. As could be proven in tests, a break in the prestressing element strand occurs practically only at this place.