U.S. patent application number 09/771724 was filed with the patent office on 2002-01-24 for intermediate anchorage for concrete structures.
Invention is credited to Wallstein, Alexander I..
Application Number | 20020007604 09/771724 |
Document ID | / |
Family ID | 25092943 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020007604 |
Kind Code |
A1 |
Wallstein, Alexander I. |
January 24, 2002 |
Intermediate anchorage for concrete structures
Abstract
An intermediate anchor having a wedge hole is placed at a
concrete construction joint. A sheathed tendon is inserted through
the intermediate anchor. Following setting of concrete poured on a
bearing side of the concrete construction joint, the sheathing of
the tendon is cut circumferentially around the tendon in a wedge
hole of the tendon. The sheathed tendon is then tensioned. This
tensioning creates an exposed portion of the tendon in the wedge
hole. A tension holding wedge is placed in the wedge hole so as to
grip the exposed portion to hold the tension. Seals on the bearing
side and a stressing side of the concrete construction joint seals
the exposed portion.
Inventors: |
Wallstein, Alexander I.;
(Chicago, IL) |
Correspondence
Address: |
MARSHALL, O'TOOLE, GERSTEIN, MURRAY & BORUN
6300 SEARS TOWER
233 SOUTH WACKER DRIVE
CHICAGO
IL
60606-6402
US
|
Family ID: |
25092943 |
Appl. No.: |
09/771724 |
Filed: |
January 29, 2001 |
Current U.S.
Class: |
52/223.13 ;
52/223.14; 52/223.6 |
Current CPC
Class: |
E04C 5/122 20130101 |
Class at
Publication: |
52/223.13 ;
52/223.14; 52/223.6 |
International
Class: |
E04B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 21, 2000 |
JP |
221412/2000 |
Claims
What is claimed is:
1. A method comprising: placing an intermediate anchor having a
wedge hole at a concrete construction joint; inserting a tendon
through the intermediate anchor leaving a sheathing of the tendon
substantially intact; making a single cut circumferentially around
the sheathing inside the wedge hole; tensioning the sheathed tendon
following setting of concrete poured on a bearing side of the
concrete construction joint, whereby the tensioning causes the
sheathing to pull away from the single cut so as to thereby create
an exposed portion of the tendon; and, gripping the exposed portion
with a wedge to hold the tension.
2. The method of claim 1 wherein the tensioning of the sheathed
tendon comprises applying a gripper wedge to the tendon outside of
the intermediate anchor.
3. The method of claim 2 wherein application of the gripper wedge
damages the sheathing of the tendon, and wherein the method further
comprises repairing the damage before pouring concrete on a
stressing side of the concrete construction joint.
4. The method of claim 3 wherein the repairing of the damage
comprises taping.
5. The method of claim 1 further comprising attaching an adaptor to
the intermediate anchor on the bearing side and inserting an O-ring
within the adaptor so as to engage the adaptor and the tendon.
6. The method of claim 5 further comprising attaching a bushing to
the adaptor so as to bias the O-ring into sealing engagement with
the adaptor and the tendon.
7. The method of claim 1 further comprising attaching a cap to the
intermediate anchor on a stressing side of the construction joint
and inserting an O-ring within the cap to engage the cap and the
tendon.
8. The method of claim 7 further comprising attaching a bushing to
the cap so as to bias the O-ring into sealing engagement with the
cap and the tendon.
9. The method of claim 7 wherein the O-ring has an inner diameter
larger than an outer diameter of the tendon.
10. The method of claim 1 further comprising: attaching an adaptor
to the intermediate anchor on the bearing side; attaching a
backside bushing to the adaptor; attaching a cap to the
intermediate anchor on a stressing side of the construction joint;
and, attaching a frontside bushing to the cap.
11. The method of claim 10 further comprising: inserting a backside
O-ring within the adaptor so as to engage the adaptor and the
tendon; and, inserting a frontside O-ring within the cap so as to
engage the cap and the tendon.
12. An intermediate anchor system for a tendon comprising: an
intermediate anchor having a backside, a frontside, and a wedge
hole arranged to receive a wedge; and, backside and frontside seals
at the backside and the frontside, respectively, of the
intermediate anchor, wherein the backside and frontside seals are
arranged to seal an exposed portion of the tendon within the wedge
hole, and wherein the exposed portion of the tendon is confined to
the wedge hole.
13. The intermediate anchor system of claim 12 wherein the backside
seal comprises an adaptor engaging the intermediate anchor and an
O-ring engaging the adaptor and the tendon.
14. The intermediate anchor system of claim 13 wherein the backside
seal further comprises a bushing biasing the O-ring into sealing
engagement with the adaptor and the tendon.
15. The intermediate anchor system of claim 12 wherein the
frontside seal comprises a cap engaging the intermediate anchor and
an O-ring engaging the cap and the tendon.
16. The intermediate anchor system of claim 15 wherein the
frontside seal further comprises a bushing biasing the O-ring into
sealing engagement with the cap and the tendon.
17. The intermediate anchor system of claim 15 wherein the O-ring
has an inner diameter at least somewhat larger than an outer
diameter of the tendon.
18. The intermediate anchor system of claim 12 wherein the backside
seal comprises an adaptor engaging the intermediate anchor and a
backside O-ring engaging the adaptor and the tendon, and wherein
the frontside seal comprises a cap engaging the intermediate anchor
and a frontside O-ring engaging the cap and the tendon.
19. The intermediate anchor system of claim 18 wherein the backside
seal further comprises a backside bushing biasing the backside
O-ring into sealing engagement with the adaptor and the tendon, and
wherein the frontside seal further comprises a frontside bushing
biasing the frontside O-ring into sealing engagement with the cap
and the tendon.
20. The intermediate anchor system of claim 12 wherein the
frontside seal comprises: a cap engaging the intermediate anchor;
an O-ring within the cap and engaging both the cap and the tendon;
and, a bushing engaging the cap so as to bias the O-ring into
sealing engagement with the cap and the tendon.
21. The intermediate anchor system of claim 12 wherein the backside
seal is on a bearing side of the intermediate anchor system, and
wherein the backside seal comprises: an adaptor having an adaptor
neck engaging an anchor neck of the intermediate anchor; an O-ring
within the adaptor and engaging both the adaptor and the tendon;
and, a bushing engaging the adaptor so as to bias the O-ring into
sealing engagement with the adaptor and the tendon.
22. The intermediate anchor system of claim 21 wherein the O-ring
is a backside O-ring, wherein the bushing is a backside bushing,
and wherein the frontside seal comprises: a cap engaging the
intermediate anchor; a frontside O-ring within the cap and engaging
both the cap and the tendon; and, a frontside bushing engaging the
cap so as to bias the frontside O-ring into sealing engagement with
the cap and the tendon.
23. The intermediate anchor system of claim 12 wherein the backside
seal is on a bearing side of the intermediate anchor system, and
wherein the backside seal comprises an adaptor and a bushing
engaging one another.
24. The intermediate anchor system of claim 23 wherein the backside
seal further comprises an O-ring biased into sealing engagement
with the adaptor and the tendon when the adaptor and the bushing
engage one another.
25. An intermediate anchor system comprising: a tendon having a
greased cable within a sheathing, wherein the tendon has an exposed
portion, and wherein the exposed portion has no sheathing; an
intermediate anchor having a backside, a frontside, and a wedge
hole arranged to receive a wedge, wherein the sheathed tendon
extends through the intermediate anchor so that the exposed portion
is within the wedge hole; a wedge within the wedge hole and clamped
to the exposed portion of the sheathed tendon; a backside seal
engaging the sheathed tendon at the backside of the intermediate
anchor; and, a frontside seal engaging the sheathed tendon at the
frontside of the intermediate anchor, wherein the backside and
frontside seals seal the exposed portion of the sheathed
tendon.
26. The intermediate anchor system of claim 25 wherein the backside
seal comprises an adaptor engaging the intermediate anchor and an
O-ring engaging the adaptor and the tendon.
27. The intermediate anchor system of claim 26 wherein the backside
seal further comprises a bushing biasing the O-ring into sealing
engagement with the adaptor and the tendon.
28. The intermediate anchor system of claim 25 wherein the
frontside seal comprises a cap engaging the intermediate anchor and
an O-ring engaging the cap and the tendon.
29. The intermediate anchor system of claim 28 wherein the
frontside seal further comprises a bushing biasing the O-ring into
sealing engagement with the cap and the tendon.
30. The intermediate anchor system of claim 28 wherein the O-ring
has an inner diameter larger than an outer diameter of the
tendon.
31. The intermediate anchor system of claim 25 wherein the backside
seal comprises an adaptor engaging the intermediate anchor and a
backside O-ring engaging the adaptor and the tendon, and wherein
the frontside seal comprises a cap engaging the intermediate anchor
and a frontside O-ring engaging the cap and the tendon.
32. The intermediate anchor system of claim 31 wherein the backside
seal further comprises a backside bushing biasing the backside
O-ring into sealing engagement with the adaptor and the tendon, and
wherein the frontside seal further comprises a frontside bushing
biasing the frontside O-ring into sealing engagement with the cap
and the tendon.
33. The intermediate anchor system of claim 25 wherein the backside
seal comprises: an adaptor engaging the intermediate anchor; an
O-ring within the adaptor and engaging both the adaptor and the
tendon; and, a bushing engaging the adaptor so as to bias the
O-ring into sealing engagement with the adaptor and the tendon.
34. The intermediate anchor system of claim 33 wherein the O-ring
is a backside O-ring, wherein the bushing is a backside bushing,
and wherein the frontside seal comprises: a cap engaging the
intermediate anchor; a frontside O-ring within the cap and engaging
both the cap and the tendon; and, a frontside bushing engaging the
cap so as to bias the frontside O-ring into sealing engagement with
the cap and the tendon.
35. The intermediate anchor system of claim 25 wherein the
frontside seal comprises: a cap engaging the intermediate anchor;
an O-ring within the cap and engaging both the cap and the tendon;
and, a bushing engaging the cap so as to bias the O-ring into
sealing engagement with the cap and the tendon.
36. A method comprising: placing an intermediate anchor having a
wedge hole at a concrete construction joint; inserting a tendon
through the intermediate anchor leaving a sheathing of the tendon
substantially intact; sealing the intermediate anchor on a bearing
side of the concrete construction joint; making a cut
circumferentially around the sheathing in the wedge hole;
tensioning the sheathed tendon following setting of concrete poured
on the bearing side of the concrete construction joint, thereby
creating an exposed portion of the tendon; gripping the exposed
portion with a wedge to hold the tension; and, sealing the
intermediate anchor on a stressing side of the concrete
construction joint.
37. The method of claim 36 wherein the sealing of the intermediate
anchor on the bearing side of the concrete construction joint
comprises attaching an adaptor to the intermediate anchor on the
bearing side and inserting an O-ring within the adaptor so as to
engage the adaptor and the tendon.
38. The method of claim 37 wherein the sealing of the intermediate
anchor on the bearing side of the concrete construction joint
further comprises attaching a bushing to the adaptor so as to bias
the O-ring into sealing engagement with the adaptor and the
tendon.
39. The method of claim 36 wherein the sealing of the intermediate
anchor on the stressing side of the concrete construction joint
comprises attaching a cap to the intermediate anchor on the
stressing side and inserting an O-ring within the cap to engage the
cap and the tendon.
40. The method of claim 39 wherein the sealing of the intermediate
anchor on the stressing side of the concrete construction joint
further comprises attaching a bushing to the cap so as to bias the
O-ring into sealing engagement with the cap and the tendon.
41. The method of claim 36 wherein the sealing of the intermediate
anchor on the bearing and stressing sides of the concrete
construction joint comprises: attaching an adaptor to the
intermediate anchor on the bearing side and inserting a backside
O-ring within the adaptor so as to engage the adaptor and the
tendon; and, attaching a cap to the intermediate anchor on the
stressing side and inserting a frontside O-ring within the cap so
as to engage the cap and the tendon.
42. The method of claim 41 further comprising: attaching a backside
bushing to the adaptor so as to bias the backside O-ring into
sealing engagement with the adaptor and the tendon; and, attaching
a frontside bushing to the cap so as to bias the frontside O-ring
into sealing engagement with the cap and the tendon.
43. The method of claim 36 wherein the sealing of the intermediate
anchor on the bearing side of the concrete construction joint
comprises: attaching an adaptor having an adaptor neck to an anchor
neck of the intermediate anchor; inserting an O-ring within the
adaptor so as to engage both the adaptor and the tendon; and,
engaging a bushing to the adaptor so as to bias the O-ring into
sealing engagement with the adaptor and the tendon.
44. The method of claim 36 wherein the sealing of the intermediate
anchor on the stressing side of the concrete construction joint
comprises: attaching a cap to the intermediate anchor; inserting an
O-ring within the cap so as to engage both the cap and the tendon;
and, engaging a bushing to the cap so as to bias the O-ring into
sealing engagement with the cap and the tendon.
45. The method of claim 36 wherein the sealing of the intermediate
anchor on the bearing and stressing sides of the concrete
construction joint comprises: attaching an adaptor having an
adaptor neck to an anchor neck of the intermediate anchor on the
bearing side; inserting a backside O-ring within the adaptor so as
to engage both the adaptor and the tendon; engaging a backside
bushing to the adaptor so as to bias the backside O-ring into
sealing engagement with the adaptor and the tendon; attaching a cap
to the intermediate anchor on the stressing side; inserting a
frontside O-ring within the cap so as to engage both the cap and
the tendon; and, engaging a frontside bushing to the cap so as to
bias the frontside O-ring into sealing engagement with the cap and
the tendon.
46. The method of claim 36 wherein the tensioning of the sheathed
tendon comprises applying a jack and a gripper wedge to the
tendon.
47. The method of claim 36 wherein the sealing of the intermediate
anchor on the bearing side of the concrete construction joint
comprises: attaching an adaptor to the intermediate anchor on the
bearing side; and, engaging a bushing to the adaptor.
48. The method of claim 36 wherein the sealing of the intermediate
anchor on the bearing and stressing sides of the concrete
construction joint comprises: attaching an adaptor to the
intermediate anchor on the bearing side; engaging a backside
bushing to the adaptor; attaching a cap to the intermediate anchor
on the stressing side; and, engaging a frontside bushing to the
cap.
49. The method of claim 36 wherein the tensioning of the sheathed
tendon damages the sheathing of the tendon, and wherein the method
further comprises repairing the damage before pouring concrete on
the stressing side of the concrete construction joint.
50. The method of claim 49 wherein the repairing of the damage
comprises taping.
51. An intermediate anchor for anchoring a tendon in concrete, the
tendon having an outside diameter, the intermediate anchor having
an O-ring to provide a seal between the intermediate anchor and the
tendon, the O-ring having an inside diameter, the inside diameter
of the O-ring being sufficiently larger than the outside diameter
of the tendon in order to permit the O-ring to move freely over the
tendon during installation.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to intermediate anchorages for
the unbonded post-tensioning tendons used to reinforce concrete
slabs and other concrete structures.
BACKGROUND OF THE INVENTION
[0002] Concrete slabs and other structures are used to form floors,
walls, and other elements of buildings. Each such concrete
structure is typically reinforced by placing an unbonded
post-tensioning tendon in a form (usually a wood form) prior to
pouring of the concrete and then tensioning the tendon after the
concrete has been poured into the form and has set. This
reinforcement permits the concrete structure to bear greater loads
than would otherwise be the case.
[0003] The tendon is composed of a greased high strength steel
cable contained within a sheathing. Additionally, the tendon is
usually provided with two terminal anchors, one at each end of the
concrete structure that is to be reinforced. The tendon is
installed in the form and the concrete is poured and allowed to
set. The tendon is then tensioned, and the tension on the tendon is
locked off at the terminal anchors. In corrosive environments such
as parking garages, corrosion protection is used to protect the
tendon and the anchors. Accordingly, it is known to provide sleeves
and seals behind the terminal anchors and caps and seals on the
frontsides of the terminal anchors.
[0004] When concrete slabs and other structures are so large that
they require two or more pours, intermediate anchors between the
terminal anchors are added to the tendon at the construction joint
between the different pours. In order to install an intermediate
anchor, the intermediate anchor is positioned at the construction
joint and the first pour of concrete is made. After this concrete
has set, sheathing is stripped from the tendon on the frontside of
the intermediate anchor so as to expose a long portion of the
cable. A jack is applied so that it grips this exposed portion with
wedges (tensioning grippers) and is operated to tension the tendon.
A wedge is then installed in the intermediate anchor so that it
grips the cable where the sheathing has been stripped away to
thereby hold the tension. The length of sheathing that is stripped
away is typically equal to the length of the jack and, therefore, a
long length of the cable is exposed.
[0005] As in the case of the terminal anchors, corrosion is also a
problem where intermediate anchors are used because, even though
the intermediate anchor is buried in concrete, concrete is porous
allowing water to carry corrosive chemicals such as salt to the
portion of the tendon that has been stripped of sheathing.
Therefore, the tendon at the intermediate anchor must also be
provided with corrosion protection.
[0006] This corrosion protection is traditionally provided by
covering the stripped portion of the tendon on the backside of the
intermediate anchor with a split plastic tube or a long solid
plastic tube with split seals. Split seals are also provided on the
frontside of the intermediate anchor in an attempt to connect back
to the sheathing. However, these traditional corrosion protection
systems do not provide adequate corrosion protection.
[0007] The present invention is directed to a sealing arrangement
and method for use in connection with an intermediate anchor that
overcomes one or more of the problems of the prior art.
SUMMARY OF THE INVENTION
[0008] In accordance with one aspect of the present invention, a
method comprises the following: (i) placing an intermediate anchor
having a wedge hole at a concrete construction joint; (ii)
inserting a tendon through the intermediate anchor leaving a
sheathing of the tendon substantially intact; (iii) making a single
cut circumferentially around the sheathing inside the wedge hole;
(iv) tensioning the sheathed tendon following setting of concrete
poured on a bearing side of the concrete construction joint,
whereby the tensioning causes the sheathing to pull away from the
single cut so as to thereby create an exposed portion of the
tendon; and, (v) gripping the exposed portion with a wedge to hold
the tension.
[0009] In accordance with another aspect of the present invention,
an intermediate anchor system for a tendon comprises an
intermediate anchor and backside and frontside seals. The
intermediate anchor has a backside, a frontside, and a wedge hole
arranged to receive a wedge. The backside and frontside seals are
at the backside and the frontside, respectively, of the
intermediate anchor. The backside and frontside seals are arranged
to seal an exposed portion of the tendon within the wedge hole, and
the exposed portion of the tendon is confined to the wedge
hole.
[0010] In accordance with still another aspect of the present
invention, an intermediate anchor system comprises a tendon, an
intermediate anchor, a wedge, a backside seal, and a frontside
seal. The tendon has a greased cable within a sheathing, the tendon
has an exposed portion, and the exposed portion has no sheathing.
The intermediate anchor having a backside, a frontside, and a wedge
hole arranged to receive a wedge. The sheathed tendon extends
through the intermediate anchor so that the exposed portion is
within the wedge hole. The wedge is within the wedge hole and is
clamped to the exposed portion of the sheathed tendon. The backside
seal engages the sheathed tendon at the backside of the
intermediate anchor. The frontside seal engages the sheathed tendon
at the frontside of the intermediate anchor. The backside and
frontside seals seal the exposed portion of the sheathed
tendon.
[0011] In accordance with yet another aspect of the present
invention, a method comprises the following: (i) placing an
intermediate anchor having a wedge hole at a concrete construction
joint; (ii) inserting a tendon through the intermediate anchor
leaving a sheathing of the tendon substantially intact; (iii)
sealing the intermediate anchor on a bearing side of the concrete
construction joint; (iv) making a cut circumferentially around the
sheathing in the wedge hole; (v) tensioning the sheathed tendon
following setting of concrete poured on the bearing side of the
concrete construction joint, thereby creating an exposed portion of
the tendon; (vi) gripping the exposed portion with a wedge to hold
the tension; and, (vii) sealing the intermediate anchor on a
stressing side of the concrete construction joint.
[0012] In accordance with a further aspect of the present
invention, an intermediate anchor is provided to anchor a tendon in
concrete. The tendon has an outside diameter. The intermediate
anchor has an O-ring to provide a seal between the intermediate
anchor and the tendon, and the O-ring has an inside diameter. The
inside diameter of the O-ring is sufficiently larger than the
outside diameter of the tendon in order to permit the O-ring to
move freely over the tendon during installation.
BRIEF DESCRIPTION OF THE DRAWING
[0013] These and other features and advantages of the present
invention will become more apparent from a detailed consideration
of the invention when taken in conjunction with the single FIGURE
of the drawing which is a partially sectioned side view of a tendon
and an intermediate anchor system according to at least one
embodiment of the present invention.
DETAILED DESCRIPTION
[0014] An intermediate anchor system 10 according to one embodiment
of the present invention is shown in the drawing. The intermediate
anchor system 10 includes an anchor main body 12 (usually a ductile
iron casting) and a cover 14 (usually a plastic coating) together
forming an encapsulated intermediate anchor 16. The cover 14 has a
neck 18 on a backside of the encapsulated intermediate anchor 16.
The neck 18 receives a neck 20 of an adaptor 22. The neck 20 of the
adaptor 22 has an external rib 24 that is formed around its
perimeter and that mates with an internal recess 26 of the neck 18
so that the adaptor 22 is positively coupled to the encapsulated
intermediate anchor 16 of the intermediate anchor system 10. The
adaptor 22 also has an internally threaded portion 28 that receives
a backside O-ring seal 30 and an externally threaded backside
bushing 32.
[0015] The encapsulated intermediate anchor 16, the adaptor 22, the
backside O-ring seal 30, and the externally threaded backside
bushing 32 are located on a bearing side 34 of a construction joint
36. Accordingly, during installation of the intermediate anchor
system 10, the encapsulated intermediate anchor 16 is suitably
attached to a form 37 such as by nailing it to the form 37 at the
construction joint 36. A tendon 38 is inserted through the
externally threaded backside bushing 32, the backside O-ring seal
30, the adaptor 22, and the encapsulated intermediate anchor 16,
and is placed in the form 37 so that, when the concrete is poured
into the form 37 during a first pour on the bearing side 34, the
tendon 38 will have its proper location. The tendon 38 is typically
composed of a plastic sheathed high strength steel cable that is
greased inside of the plastic sheathing.
[0016] The adaptor 22 is affixed to the encapsulated intermediate
anchor 16 by inserting the neck 20 into the neck 18 until the
external rib 24 snaps into the recess internal recess 26 of the
neck 18. The externally threaded backside bushing 32 is then
threaded into the adaptor 22 until the backside O-ring seal 30 is
forced into sealing engagement with the tendon 38 and the adaptor
22. Accordingly, the backside O-ring seal 30 together with the
adaptor 22 and the tendon 38 seals the encapsulated intermediate
anchor 16 on the bearing side 34 of the construction joint 36. A
secondary O-ring 30a provides a seal between the adapter 22 and the
neck 18 of the encapsulated intermediate anchor 16.
[0017] An open cap 40 is applied to a frontside of the encapsulated
intermediate anchor 16 and has a rib 42 around an external
perimeter of the open cap 40. The encapsulated intermediate anchor
16 has a complementary rib 44 around an internal perimeter thereof.
The open cap 40 has an internally threaded portion 46 that
threadably engages an externally threaded frontside bushing 48. The
open cap 40, the externally threaded frontside bushing 48, and an
O-ring 50 are placed on the tendon 38, but are not engaged to one
another until tensioning of the tendon 38 on the bearing side 34 is
complete. To permit the O-ring 50 to move easily over the tendon
38, the inner diameter of the O-ring 50 is at least somewhat larger
than the outer diameter of the tendon 38. This feature is important
because intermediate anchors are applied to tendons off-site and
the tendons with their corresponding intermediate anchors mounted
thereon are then moved to the site for final installation.
Therefore, it is frequently necessary to move intermediate anchors
over long runs of their tendons which could damage the O-rings if
the O-rings cannot move freely over their tendons.
[0018] Concrete may then be poured on the bearing side 34 of the
construction joint 36. A pocket former may be applied to the
encapsulated intermediate anchor 16 prior to pouring of the
concrete in order to prevent concrete from flowing into a wedge
hole 52 of the encapsulated intermediate anchor 16. After pouring,
this pocket former may then be removed.
[0019] Once the concrete sets on the bearing side 34, a
circumferential cut is made around the sheathing of the tendon 38
within the wedge hole 52 of the encapsulated intermediate anchor
16. The tendon 38 is then tensioned by placing the nose of a
hydraulic jack against the encapsulated intermediate anchor 16 on a
stressing side 54 of the construction joint 36. A gripper wedge 56
is placed on the tendon 38 at the opposing end of the hydraulic
jack so that the gripper wedge 56 penetrates the sheathing of the
tendon 38 and engages the steel cable within the sheathing. The
tendon 38 is tensioned with the gripper wedge 56 by use of the
jack.
[0020] During tensioning, the steel cable of the tendon 38
stretches. Because the sheathing is bonded to the cured concrete on
the bearing side 34, the sheathing of the tendon 38 in the wedge
hole 52 will open as the steel cable stretches, thereby creating an
exposed portion 58 in the sheathing. After a proper amount of
tensioning has been applied to the tendon 38, a permanent wedge 60
surrounding the exposed portion 58 of the tendon 38 is placed into
the wedge hole 52 of the encapsulated intermediate anchor 16. When
the jack is released, force is transferred from the gripper wedge
56 to the permanent wedge 60 so as to lock off the tension in the
tendon 38 on the bearing side 34 of the construction joint 36.
[0021] The open cap 40 is then attached to the encapsulated
intermediate anchor 16 so that the rib 42 is captured by the
corresponding rib 44 to thereby lock the open cap 40 onto the
encapsulated intermediate anchor 16 and to thereby compress a
gasket 61 to form a seal between the open cap 40 and the
encapsulated intermediate anchor 16. The externally threaded
frontside bushing 48 is threaded into the internally threaded
portion 46 until the frontside O-ring seal 50 is biased against the
tendon 38 and against the internally threaded portion 46 of the
open cap 40 to form a seal around the tendon 38 to thereby seal the
encapsulated intermediate anchor 16 on the stressing side 54 of the
construction joint 36.
[0022] Also, the gripper wedge 56 penetrates the sheathing during
tensioning of the tendon 38, thereby damaging the sheathing at that
location. This damaged portion of the sheathing may be repaired
such as by taping so as to restore the integrity of the
sheathing.
[0023] Accordingly, the exposed portion 58 of the tendon 38 is
sealed by the encapsulated intermediate anchor 16, the adaptor 22,
the backside O-ring seal 30, and the externally threaded backside
bushing 32 on the bearing side 34 of the construction joint 36, and
by the encapsulated intermediate anchor 16, the open cap 40, the
frontside O-ring seal 50, and the externally threaded frontside
bushing 48 on the stressing side 54 of the construction joint 36.
Thereafter, concrete may be poured into the form 37 during a second
pour on the stressing side 54.
[0024] Certain modifications of the present invention will occur to
those practicing in the art of the present invention. Accordingly,
the description of the present invention is to be construed as
illustrative only and is for the purpose of teaching those skilled
in the art the best mode of carrying out the invention. The details
may be varied substantially without departing from the spirit of
the invention, and the exclusive use of all modifications which are
within the scope of the appended claims is reserved.
* * * * *