U.S. patent application number 10/517988 was filed with the patent office on 2005-11-17 for tensioning device for strip-shaped tension members.
Invention is credited to Andra, Hans-Peter, Maier, Markus.
Application Number | 20050252116 10/517988 |
Document ID | / |
Family ID | 31984425 |
Filed Date | 2005-11-17 |
United States Patent
Application |
20050252116 |
Kind Code |
A1 |
Maier, Markus ; et
al. |
November 17, 2005 |
Tensioning device for strip-shaped tension members
Abstract
A tensioning device for strip-shaped tension members on
supporting structures, especially concrete supporting structures,
exhibits a tensioning traverse, which is detachably fastened to a
base plate that is permanently fastened to the supporting
structure. A prestressing ancho), which is connected to the
strip-shaped tension member by means of clamping, may be displaced
by means of pressing elements for the purpose of applying tension
to tension member and supported against the tensioning traverse or
the base plate. A guide body, which supports the tension member so
that it may glide, at least upward, is arranged between the
tensioning traverse and the prestressing anchor so as to be
stationary. The guide body exhibits a guide slit that accommodates
the tension member so that it can glide, and it is mounted on a
guide support that is connected to the tensioning traverse so as to
be deflection resistant.
Inventors: |
Maier, Markus; (Stuttgart,
DE) ; Andra, Hans-Peter; (Stuttgart, DE) |
Correspondence
Address: |
WHITE, REDWAY & BROWN LLP
1217 KING STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
31984425 |
Appl. No.: |
10/517988 |
Filed: |
December 15, 2004 |
PCT Filed: |
August 16, 2003 |
PCT NO: |
PCT/EP03/09079 |
Current U.S.
Class: |
52/223.1 |
Current CPC
Class: |
E04G 2023/0251 20130101;
E04G 2023/0255 20130101; E04G 2023/0259 20130101; E04G 2023/0262
20130101; E04G 23/0218 20130101; E04C 5/127 20130101; E04C 5/085
20130101; E04G 21/121 20130101 |
Class at
Publication: |
052/223.1 |
International
Class: |
E04C 005/08 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2002 |
DE |
102 49 266.2 |
Claims
1. A tensioning device for strip-shaped tension members on
supporting structures, especially concrete supporting structures,
with a tensioning traverse, which is detachably fastened to a base
plate that is permanently fastened to the supporting structure,
whereby a prestressing anchor, connected to the strip-shaped
tension member by means of clamping, may be displaced by means of
pressing elements that are supported on the tensioning traverse for
the purpose of applying tension to the tension member and against
the tensioning traverse or the base plate, wherein a guide body,
which supports the tension member so that it can glide, at least
upward, is arranged between the tensioning traverse and the
prestressing anchor in a stationary manner.
2. A tensioning device according to claim 1, wherein the guide body
exhibits a guide slit that can accommodate the tension body so that
it can glide.
3. A tensioning device according to claim 1, wherein the guide body
is applied to a guide support that is connected to the tensioning
traverse so as to be deflection resistant.
4. A tensioning device according to claim 3, wherein the guide body
is arranged on the top of the tension member and exhibits lateral
sections that protrude laterally beyond the tension member, which
are detachably fastened to a bracket that lies beneath the tension
member.
5. A tensioning device according to claim 1, wherein the pressing
elements lie in the plane of the tension member.
6. A tensioning device according to claim 1, wherein the support of
the prestressing anchor occurs by the use of blocks or the like in
the plane of the tension member.
Description
[0001] The invention relates to a tensioning device for
strip-shaped tension members on supporting structures, particularly
concrete supporting structures, with a tensioning traverse that is
detachably fastened to a base plate that is permanently fastened to
the supporting structure, such that a prestressing anchor that is
connected to the strip-shaped tension member by means of clamping,
may be shifted by means of pressing elements for the purpose of
tightening the tension member and may be supported against the
tensioning traverse or the base plate.
[0002] To enhance (upgrade) the load-bearing capacity, or to
restore the original load-bearing capacity of supporting structures
made of steel-reinforced concrete (restoration), or pre-stressed
concrete, the application of band-shaped tension members to the
surface of the concrete after the fact is known. Lamella-like
plastic strips, with embedded carbon fibers, for example, are used
as tension members. For anchoring, base plates made of steel, for
example, are pinned into recesses in the surface of the concrete
and/or fastened by adhesion.
[0003] In order to apply the requisite pre-tension to the
strip-shaped tension member prior to its permanent anchoring, a
tensioning device is applied to one end of the tension member,
which device is removed again after the tensioning process and the
firm positioning of the tension member on the concrete supporting
structure, for example, by means of permanent clamping and/or
adhesion.
[0004] In the case of a known tensioning device of the type alluded
to at the outset (DE 198 49 605 A1), the free end of the
strip-shaped tensioning member is clamped into a temporary
prestressing anchor, which is moved away in lateral guides by means
of pressing elements, such as hydraulic cylinders, for example, by
a tensioning traverse that is applied to the base plate in such a
way that it can be detached, whereby the tension member is
tightened. To establish the final tensioning position, using a
block, the prestressing anchor is braced against the base plate.
After the permanent anchoring of the tension member by means of
clamping and/or adhesion, the tensioning device is removed.
[0005] The prestressing anchor can only be held in a stable
position that lies adjacent to the surface of the concrete by
virtue of the fact that the lateral guides are connected with the
tensioning traverse so as to be deflection resistant, in order to
accept the bending stresses that occur toward the top when avoiding
the prestressing anchor. This necessitates considerable effort and
expense in construction, as a result of which the tensioning device
becomes not only heavy and cumbersome, but the requisite space is
increased as well, so that a relatively large recess must be
produced in the surface of the concrete in order to accommodate the
arrangement of the tensioning device.
[0006] It is, therefore, the task of the invention to embody a
tensioning device of the type alluded to at the outset in such a
manner that the prestressing anchor is held stably in its desired
position by the forces that occur in the tensioning process,
without imposing any flexion stress upon the guides.
[0007] According to the invention, this task is resolved by virtue
of the fact that a guide body that supports the tension member,
which may be glided upward at least is arranged between the
tensioning traverse and the prestressing anchor in a stationary
manner.
[0008] The guide body constitutes, at some distance ahead of the
tensioning traverse, a reversal point for the tension member. If
one regards the support point of the pressing elements and the
lateral guides, guide rods, for example, on the tensioning traverse
as an articulation, the prestressing anchor can move only in a
circular path whose radius is greater than the distance that exists
between the guide body and the prestressing anchor. In order to
permit this slewing motion of the prestressing anchor, the tension
member would have to be extended, and thus, put under even further
tension. The tensile force exerted by the tension member upon the
prestressing anchor therefore holds the prestressing anchor in a
stable manner in its prescribed position on the supporting
structure, for example, the surface of the concrete, without
subjecting the guide rods to any flexion stress in the process. The
guide rods, which are subjected to pressure exclusively, can
therefore be embodied in relatively slender fashion, since they
need not transfer any bending torques. By these means, the
tensioning device, overall, becomes light and relatively narrow so
that its lateral spatial requirement is slight and the size of the
requisite recess in the surface of the supporting structure, the
surface of the concrete, for example, is limited.
[0009] Since the guide body, which supports the tension member
toward the top is arranged in the area of the tension member, and
thus does not protrude laterally beyond the guide rods, it does not
enlarge the dimensions of the tensioning device.
[0010] The guide body preferably accommodates the tension member in
a guide slit so that it can glide, so that guidance of the tension
member is achieved on all sides.
[0011] According to a preferred embodiment of the invention,
provision is made so that the guide body is applied to a guide
support that is connected to the tensioning traverse so as to be
deflection resistant. By these means, the retaining force applied
to stabilize the tension member is transferred directly to the
tensioning traverse. A separate attachment of the guide body, which
would be possible on the concrete supporting structure, for
example, becomes non-essential as a result of this embodiment of
the thought behind the invention.
[0012] Preferably, the guide support is arranged on the top of the
tension member and it exhibits lateral sections that protrude
laterally beyond the tension member, which are detachably fastened
with a shackle that lies beneath the tension member. Thus, the
guide body, which exhibits a guide slit, can be released simply
after the tensioning process is terminated and the tension member
is secured.
[0013] Preferably, provision is made so that the pressing elements
lie in the plane of the tension member and so that the supporting
of the prestressing anchor using supporting blocks or the like,
occurs in the plane of the tension member. By these means, when
tension is supplied and support is supplied by blocks, an unstable
equilibrium is achieved, which must merely be assured by the guide
body, without requiring the guide body to accept significant
forces.
[0014] In what follows, the invention is elucidated by virtue of
one embodiment, which is depicted in the drawing(s).
[0015] FIG. 1 shows a strip-shaped tension member applied to a
concrete supporting structure with an anchoring device on its fixed
side and a tensioning device on its tensioning side, in top
view,
[0016] FIG. 2 shows a section along the line II-II in FIG. 1,
[0017] FIG. 3 shows a section along the line III-III in FIG. 1
and
[0018] FIG. 4 shows a schematic representation of the conditions of
movement at the tensioning device in a section similar to FIG.
2.
[0019] A strip-shaped tension member 1, for example, a carbon fiber
reinforced plastic lamella, is intended to be fastened to the
surface of a supporting structure, a concrete supporting structure
2 in the case of the embodiment shown. Similarly, use in the case
of other supporting structures, made of steel or wood, for example,
is also possible. Prior to its fixation to the concrete supporting
structure 2, tension member 1 must be pre-stressed.
[0020] Tension member 1 is firmly fastened, by means of a clamping
plate 3, upon which several clamping shackles have an effect, to a
base plate 5, which, by means of pins 6 and an adhesive layer 7, is
secured in a recess 8 of the concrete supporting structure at the
end that has the fixed side (on the right in FIGS. 1 and 2).
[0021] In similar fashion, at the end of the tension member 1 on
the side subjected to tension (on the left in FIGS. 1 and 2), a
base plate 9 is secured by means of pins 10 and an adhesive layer
111 in a recess 12 of the concrete supporting structure 2. Before
the end of tension member 1 on the side subjected to tension is
anchored to the base plate 9, likewise by means of a clamping plate
(not yet depicted in FIGS. 1 and 2) and, if necessary, before
adhesion to the base plate 9, the tension member 1 must be
pre-stressed. A tensioning device 13 is used to this end. The
tensioning device 13 exhibits a tensioning traverse 14, which is
equipped with two straps 15, which are detachably fastened to the
base plate 9 on either side of tension member 1 by means of screws
16. Thus, a deflection resistant, detachable connection is created
between the tensioning traverse 14 and the base plate 9.
[0022] Two pressing elements 17, which are, in the case of the
embodiment depicted, embodied as hydraulic cylinders, are supported
on the tensioning traverse 14 on the side that is turned away from
the base plate 9 (designated in this context as "on the tension
side"). Both pressing elements 17 lie in the plane of the tension
member 1. They press a prestressing anchor 18 away from the
tensioning traverse 14. The prestressing anchor 18 is, on either
side, guided on lateral guide rods 19, which are connected with the
tensioning traverse 14. The prestressing anchor 18 can be secured,
in its tensioning position, to the lateral guide rods 19, so that
even after the detachment of the pressing elements 17, it is
supported by way of the guide rods 19 on the tensioning traverse
14. Instead of that, another type of support by blocks can be
selected as well, in order to support the prestressing anchor. The
support or shoring up by blocks in this embodiment lies in the
plane of tension member 1 in this embodiment.
[0023] The prestressing anchor 18 exhibits a sub-plate 20, upon
which the tension member 1 lies. The tension member 1 is clamped by
clamping shackle 21, clamping screws 22, and a clamping plate 23
against sub-plate 20 and fastened, in this way, to the prestressing
anchor 18.
[0024] A guide support 24 is embodied with the tensioning traverse
14 as one piece, welded to the latter or fastened so as to be
deflection resistant to the tensioning traverse in some other
manner, by means of screws, for example, and [it] constitutes, at
its free end, a guide body 25 that lies on the top of the tension
member 1, which is located between the tensioning traverse 14 and
the prestressing anchor 18 and is arranged at some distance on the
tensioning side relative to the tensioning traverse 14.
[0025] The guide body 25, which is arranged on the top of the
tension member 1, exhibits lateral sections, 26 that protrude
laterally beyond tension member 1, which are detachably fastened,
preferably by means of lateral screws, 28, with a bracket 27 that
lies beneath the tension member 1. The guide body 25 need not
necessarily be connected with the tensioning traverse 14: it can
also be applied to its location in stationary fashion, connected,
for example, with the supporting structure, here, with the concrete
supporting structure 2.
[0026] A guide slit 29, which accommodates tension member 1 so that
it can glide, is constituted between the guide body 25 and the
bracket 27.
[0027] As represented in schematic fashion in FIG. 4, the guide
body 25 constitutes a reversal point for tension member 1, which
lies at a distance ahead of the tensioning traverse 14 on the same
side as the tension.
[0028] If one assumes that the lateral guide rods 19 are applied to
the tensioning traverse 14 after the manner of pendulum supports so
as to be articulated, the result, for prestressing anchor 18 is a
possibility of movement on a radius R, which is equal to the
distance between the tensioning traverse 14 and the prestressing
anchor 18.
[0029] For the end of the tension body that protrudes from the
guide body 25, the result, however, is a theoretical possibility of
movement on a radius r, which corresponds to the distance between
the guide body 25 and the prestressing anchor 18, and is markedly
smaller than the radius R. In order to render a movement of the
prestressing anchor 18 possible on a circular path with the
structurally prescribed radius of movement R, the tension member 1
would thus have to be extended further. Thus, the prestressing
anchor 18 is found in its location, as depicted in FIG. 4, in a
stable position, and it is kept in this stable position without, in
the process, necessitating the imposition of any flexion stress
upon the lateral guide rods 19.
* * * * *