Static structures (e.g. – buildings) – With component having discrete prestressing means – Anchorage
Patent
1993-09-27
1996-02-27
Friedman, Carl D.
Static structures (e.g., buildings)
With component having discrete prestressing means
Anchorage
E04C 512
Patent
active
054938287
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a stressing anchorage for prestressing elements in a part of a structure.
By the term stressing anchorage, dead end anchorages are also to be understood in the following.
A stressing anchorage of this kind for prestressing elements usually comprises a support device in the form of a bearing plate with trumpet and an anchor head, which is designed normally as a cylinder-shaped body of high quality steel. The anchor head has one or more continuous bores, running essentially parallel to the longitudinal axis of the head, through which are led the ends of the prestressing elements of a stressing anchorage. One of the two faces of the anchor head usually lies on one bearing plate. The said continuous bore or continuous bores, respectively, have conical extensions in the area of the other, second face turned away from the bearing plate, which extensions open toward the second face. Each of the conical extensions is intended to accept a frustoconical clamp, which serves to hold one each of the penetrating parts of the prestressing element in the form of a strand of the prestressing element, following stressing of the prestressing element.
BACKGROUND OF THE INVENTION
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.
SUMMARY OF THE INVENTION
The object of the invention consists in creating a stressing anchorage of such a quality that a more even load distribution is achieved in the area of the wedge to the prestressing element strand, and with which in addition a lighter and more cheaply produced anchor head can be used.
In such a stressing anchorage in stressed state of the prestressing element, the conoidal surfaces of the frustoconical wedge lie better on the cone-shaped surface of the anchor head formed by the mortar-like hardened mass. The mortar-like, hardened mass is more ductile, i.e. more workable than the steel of which the frustoconical wedges are made, and consequently adapts to the contour of the frustoconical wedges during the stressing process. Achieved in this way is a more even load distribution from the wedge to the clamped part of the prestressing element strand. The aforementioned clear load peak in the area of the smaller diameter of the frustoconical wedge is considerably reduced whereby protection is increased against the breaking load of the prestressing element.
An advantageous design of the invention consists in that the conical extension of the bore of the anchor head, which serves to accept the frustoconical clamp, has a second extension in its end area of greater diameter. Thus in this end area the end of the wedge does not come into contact with the mortar-like mass of the anchor head. This end area of the bore of the anchor head is thereby protected in the stressing process and in after-tensioning, during which the wedge is pulled out of the bore of the anchor head by a certain amount. Damage to the end area of the
REFERENCES:
patent: 3524228 (1970-08-01), Kelly
patent: 3605202 (1971-09-01), Barredo de Valenzuela
patent: 4619088 (1986-10-01), Garcia-Mansilla
patent: 4773198 (1988-09-01), Reinhart
patent: 4819393 (1989-04-01), Augoyard
patent: 4837995 (1989-06-01), Omizono et al.
Rogowsky David
Siegfried Erwin
Friedman Carl D.
Nguyen Kien T.
VSL International AG
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