Vsl International Ag

Erwin Siegfried

David Rogowsky

Peter Marti

Stressing anchorage for prestressing elements in a part of a structure

The force transfer body comprises a first, essentially annular partial body, preferably of cast steel, and a second partial body, preferably of a castable mortar mass capable of hardening. The second partial body is cast in one piece with the first partial body. An inner conical aperture is lined with a funnel-shaped plastic part, which overlaps at least a section of the first partial body. The first partial body has an abutting surface, turned away from the part of the structure, serving the firm contact with an anchor head containing individual members. The prestressing forces arising concentratedly with the anchorage are conveyed from the anchor head via the first partial body into the second partial body, and from there into the part of the structure. The second partial body is designed essentially frustoconical, the truncated cone extending, tapering, away from the first partial body. In the area of the outer generated surface of the second partial body there is a circumferential constriction. Achieved thereby, on the one hand, is the provision of an annular surface, formed by the circumferential constriction, to convey the prestressing forces to the part of the structure, in addition to the smaller face turned away from the first partial body. The specific compressive stress on the concrete of the part of the structure is thereby decreased. Thanks to this particular construction and given shape, the inventive force transfer body can be realized more easily, compared to bearing plates, poured anchor bodies or prior art anchor bodies.

Force transfer body for an anchorage

The prestressed concrete lining has several reinforcement elements (32) distributed around the circumference and along the length of the pressure tunnel. There are prestressing elements (38, 39, 40, 41) which encompass at least a part of the circumference of the pressure tunnel. A bottom part (35) is disposed within the pressure tunnel, formed of several elongated anchorage bodies (15) in series. Each of the anchorage bodies (15) has an essentially U-shaped cross section. In each of the arms (2, 3) of the anchorage bodies turned towards the inside of the tunnel there are first means (5) for passing through at least one of each of the prestressing elements (38, 39, 40, 41). An bearing plate (8) is disposed on each of the facing inner surfaces of the arms in the region of each of the first pass-through means (5). Second means (10) for passing through at least one of each of the prestressing elements (38, 39, 40, 41) are foreseen in the base arm of the anchorage body 15. Each of the prestressing elements (38, 39, 40, 41) is, starting from a dead end anchor (43, 44), led through one of the second pass-through means (10) of one of the anchorage bodies (15) and, after crossing through one of the first pass-through means (5) of one of the anchorage bodies, ends in an anchor head of a stressing anchorage (42) bordering on one of the bearing plates (8). By use of the anchorage bodies a prestressed concrete lining can be simplified with respect to the state of the art. In particular, it guarantees speedy advancement in the progress of the construction. The construction time is therefore reduced.

Prestressed concrete lining in a pressure tunnel

The wall (5) of the encasing tube (1) includes spiralling protrusions (3, 4). First protrusions (3) and second protrusions (4) run either in different directions or in the same direction but at different pitches. The encasing tube is used for enclosing tensioning cable (2) in concrete structures. By means of the particular arrangement of the protrusions, the flow properties of the grout are improved, air bubbles are virtually eliminated during injection, and the bonding properties of tensioning cables are improved by means of large bonding zones while respecting the required high fatigue strength.

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Liebefeld, Switzerland

Erwin Siegfried