US20020083659A1

US20020083659A1 - Method and apparatus for sealing an intermediate anchorage of a post-tension system

Info

Publication number: US20020083659A1
Application number: US09/752,036
Authority: US
Inventors: Felix Sorkin
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-12-29
Filing date: 2000-12-29
Publication date: 2002-07-04

Abstract

An intermediate anchorage for a post-tension system including an anchor member, a tendon extending through an interior passageway of the anchor and a sleeve formed of a heat shrink material and extending over the unsheathed portion of the tendon. The sleeve is affixed in heat sealed compressive contact with a surface of the anchor member and with an exterior surface of the sheathed portion so as to maintain the unsheathed portion in a liquid-tight environment. The sleeve can be a tubular member, a split tubular member or a wrapping material. The anchor member is an encapsulated anchor having a tubular extension extending outwardly therefrom such that the sleeve is secured in sealed compressive contact with the tubular extension.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to post-tensioning systems. More particularly, the present invention relates to post-tensioning systems having intermediate anchorages. Furthermore, the present invention relates to sealing devices for preventing liquid intrusion into the exposed sections of tendon in the post-tension system.

2. Description of Related Art

For many years, the design of concrete structures imitated the typical steel design of column, girder and beam. With technological advances in structural concrete, however, its own form began to evolve. Concrete has the advantages of lower cost than steel, of not requiring fireproofing, and of its plasticity, a quality that lends itself to free flowing or boldly massive architectural concepts. On the other hand, structural concrete, though quite capable of carrying almost any compressive load, is weak in carrying significant tensile loads. It becomes necessary, therefore, to add steel bars, called reinforcements, to concrete, thus allowing the concrete to carry the compressive forces and the steel to carry the tensile forces.

Structures of reinforced concrete may be constructed with load-bearing walls, but this method does not use the full potentialities of the concrete. The skeleton frame, in which the floors and roofs rest directly on exterior and interior reinforced-concrete columns, has proven to be most economic and popular. Reinforced-concrete framing is seemingly a quite simple form of construction. First, wood or steel forms are constructed in the sizes, positions, and shapes called for by engineering and design requirements. The steel reinforcing is then placed and held in position by wires at its intersections. Devices known as chairs and spacers are used to keep the reinforcing bars apart and raised off the form work. The size and number of the steel bars depends completely upon the imposed loads and the need to transfer these loads evenly throughout the building and down to the foundation. After the reinforcing is set in place, the concrete, a mixture of water, cement, sand, and stone or aggregate, of proportions calculated to produce the required strength, is placed, care being taken to prevent voids or honeycombs.

One of the simplest designs in concrete frames is the beam-and-slab. This system follows ordinary steel design that uses concrete beams that are cast integrally with the floor slabs. The beam-and-slab system is often used in apartment buildings and other structures where the beams are not visually objectionable and can be hidden. The reinforcement is simple and the forms for casting can be utilized over and over for the same shape. The system, therefore, produces an economically viable structure. With the development of flat-slab construction, exposed beams can be eliminated. In this system, reinforcing bars are projected at right angles and in two directions from every column supporting flat slabs spanning twelve or fifteen feet in both directions.

Reinforced concrete reaches its highest potentialities when it is used in pre-stressed or post-tensioned members. Spans as great as one hundred feet can be attained in members as deep as three feet for roof loads. The basic principle is simple. In pre-stressing, reinforcing rods of high tensile strength wires are stretched to a certain determined limit and then high-strength concrete is placed around them. When the concrete has set, it holds the steel in a tight grip, preventing slippage or sagging. Post-tensioning follows the same principle, but the reinforcing tendon, usually a steel cable, is held loosely in place while the concrete is placed around it. The reinforcing tendon is then stretched by hydraulic jacks and securely anchored into place. Pre-stressing is done with individual members in the shop and post-tensioning as part of the structure on the site.

In a typical tendon tensioning anchor assembly used in such post-tensioning operations, there are provided anchors for anchoring the ends of the cables suspended therebetween. In the course of tensioning the cable in a concrete structure, a hydraulic jack or the like is releasably attached to one of the exposed ends of each cable for applying a predetermined amount of tension to the tendon, which extends through the anchor. When the desired amount of tension is applied to the cable, wedges, threaded nuts, or the like, are used to capture the cable at the anchor plate and, as the jack is removed from the tendon, to prevent its relaxation and hold it in its stressed condition.

There are many post-tension systems employing intermediate anchorages where the length of the slab is too long to tension with a single anchor. In these systems, the intermediate anchor is interposed between a live end and a dead end anchor. In the construction of such intermediate anchorage systems, the tendon extends for a desired length to the intermediate anchor. A portion of the sheathing is removed in the vicinity of the intermediate anchor. The intermediate anchor is installed onto a form board in accordance with conventional practice. The unsheathed portion of the tendon is received by a tensioning apparatus such that the tendon is stressed in the area between the dead end anchor and the intermediate anchor. After stressing the tendon, concrete is poured over the exterior of the sheathed tendon and over the dead end anchor and intermediate anchor. The remaining portion of the tendon extends from the intermediate anchor to either another intermediate anchorage or to the live end anchor. Intermediate anchorage systems are employed whenever the slab is so long that a single live anchor extending to a single dead end anchor is inadequate. For example, two intermediate anchorages would be used for slabs having a length of approximately 300 feet.

A problem that affects many of the intermediate anchorage systems is the inability to effectively prevent liquid intrusion into the unsheathed portion of the tendon. Normally, the unsheathed portion will extend outwardly, for a distance, from the intermediate anchor in the direction toward the dead end anchor. Additionally, another unsheathed portion will extend outwardly at the intermediate anchor toward the live end anchor. In normal practice with a single live anchor and without intermediate anchors, a liquid-tight tubular member is placed onto an end of the anchor so as to cover the unsheathed portion of the tendon. This is relatively easy to accomplish since the length of the tendon is minimal at the live end. However, it is a considerable burden to attempt to slide such a tubular member along the entire length of the tendon so as to form the liquid-tight seal at the intermediate anchorage. In normal practice, tape, or other corrosion protection materials, are applied to the exposed portion of the tendon adjacent the intermediate anchorage. Extensive practice with this technique has shown that it is generally ineffective for preventing liquid intrusion into the interior of the tendon or into the interior of the intermediate anchorage. As such, a great need has developed in which to protect the exposed areas of the tendon adjacent the intermediate anchorage.

The present inventor is the inventor of the subject matter of U.S. Pat. No. 5,749,185, issued on May 12, 1998 and U.S. Pat. No. 6,098,356, issued on Aug.8, 2000. U.S. Pat. No. 5,749,185 describes a method for sealing an intermediate anchorage of a post-tension system which utilizes a split tubular member received at one end by the anchor member and extending over the sheathed portion of the tendon. The split tubular member has another end extending over the sheathed portion of the tendon. The split tubular member has a first longitudinal edge and a second longitudinal edge extending therealong. The longitudinal edge are separable for a distance greater than a diameter of the tendon so as to allow the tendon to be placed into an interior of the tubular member. A seal is formed between the longitudinal edges so as to prevent liquid intrusion into the interior of the tubular member.

U.S. Pat. No. 6,098,356 described an apparatus for sealing an intermediate anchorage of a post-tension anchor system in which a cap has an attachment section thereon. The attachment section was adapted to allow the cap to be connected to the end of the anchor body. The cap has a tubular member extending outwardly from the attachment section. The cap has a grease fitting formed therein which allows grease to be introduced into the interior passageway of the tubular member. The grease fitting extends transverse to the longitudinal axis of the tubular member.

Polyolefins can be used to prepare shrink wraps. Other suitable synthetic resins include ionomers, polyvinyl chlorides, polyesters, polystyrene and polyvinylidene chlorides. A shrink wrap's distinguishing characteristic is its ability, upon exposure to some level of heat, to shrink or, if restrained, to create shrink tension within the wrap. This ability is activated by the packager when the wrapped product is passed through a hot air or hot water shrink tunnel. The resulting shrinkage of the wrap results in an aesthetically pleasing transparent or opaque wrapping which conforms to the contour of the product while providing the usual functions required of packaging materials, such as protection of the product from loss of components, pilferage or damage due to handling and shipment. The manufacturing of shrink wrap requires relatively sophisticated equipment including extrusion lines with “racking” capability, irridiation units when cross-linking is desired, tenter frames, mechanical center folders and slitters. “Racking” or “tenter framing” are conventional orientation processes which cause the wrap to be stretched in the cross or transverse direction and in the longitudinal or machined direction. The wraps are usually heated to their orientation temperature range which varies with different polymers but is usually above room temperature and below the polymer's melting temperature. After being stretched, the wrap is rapidly cooled to quench it, thus freezing the molecules in there oriented state. Upon heating, the orientation stresses are relaxed and the wrap will begin to shrink back to its original unoriented dimension.

In certain situations, it is desirable to effect shrinkage along a single axis without substantial shrinkage in the cross-direction. In order to obtain uniaxially shrinkable materials, it is possible to employ uniaxially oriented materials. A metallized uniaxially heat shrinkable, biaxially oriented, multilayer film having a polypropylene containing core layer can be utilized so as to provide strength to the uniaxially shrinkable material. The core layer can include an isotactic polypropylene and a modifier which reduces the crystallinity of the propylene containing core layer. A layer of aluminum can be deposited on the multilayer film structure. One such uniaxially high strength durable shrink wrap material is manufactured by Canusa of The Woodlands, Tex.

It is an object of the present invention to provide an intermediate anchorage for a post-tension system which forms an effective seal over the exposed portions of the tendon in the area of the intermediate anchorage.

It is a further object of the present invention to provide a sealing apparatus for attachment to the intermediate anchorage which prevents liquid intrusion.

It is a further object of the present invention to provide a method and apparatus which prevents liquid intrusion into the unsheathed portion of the tendon which is easy to install and easy to use.

It is still a further object of the present invention to provide a sealing method and apparatus which avoids the need to thread the anchor and the sealing materials along the entire length of the tendon to the area of the intermediate anchorage.

It is still another object of the present invention to provide a sealing method and apparatus which is easy to manufacture and relatively inexpensive.

These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.

BRIEF SUMMARY OF THE INVENTION

The present invention is an intermediate anchorage for a post-tension system comprising an anchor member having an interior passageway extending therethrough, a tendon extending through the interior passageway of the anchor member, and a first sleeve formed of a heat shrink material. The first sleeve is received at one end by the anchor member and extends over the unsheathed portion of the tendon. This first sleeve has another end extending over the sheathed portion of the tendon. The first is in heat sealed compressive contact with a surface of the anchor and with an exterior surface of the sheathed portion.

In one form of the present invention, the anchor has a tubular member extending outwardly therefrom. This first sleeve is in heat sealed compressive contact with the tubular member of the anchor. The tendon will also have a sheathed portion and an unsheathed portion extending outwardly from an opposite side of the anchor member. The present invention can include a second sleeve which is formed of a heat shrink material so as to extend over this unsheathed portion of the tendon. The second sleeve is in heat-sealed compressive contact with another surface of the anchor and with the exterior surface of the tendon extending outwardly from the opposite side of the anchor member. The anchor member can have a cap affixed thereto which extends outwardly therefrom. The tendon will extend through the cap. The second sleeve is in heat-sealed compressive contact with the exterior surface of the cap.

Each of the first sleeve and the second sleeve are in liquid-tight relationship with the surface of the anchor member and with the respective sheathed portions of the tendon.

In a particular form of the present invention, the first sleeve can be a split tubular member having a single split extending longitudinally therealong. The split tubular member can have a seal formed for joining the edges of the split tubular member together around the tendon. In particular, this single split of the split tubular member has a first longitudinal edge and a second longitudinal edge. The first longitudinal edge is in overlapping relationship with an exterior surface of the split tubular member adjacent to the second longitudinal edge. In another form of the present invention, the first and second sleeves can be a wrapping which is wrapped around the unsheathed portion of the tendon, the sheathed portion of the tendon and the surface of the anchor member.

The present invention is also a method of forming a seal for an intermediate anchorage in a post-tension system comprising the steps of: (1) extending a tendon through an interior passageway of the intermediate anchorage; (2) stressing the tendon such that an unsheathed portion of the tendon extends outwardly of one side of the intermediate anchorage; (3) positioning a sleeve over a sheathed portion of the tendon and over an unsheathed portion of the tendon and over a surface of the intermediate anchorage; and (4) heating the sleeve such that the sleeve reduces in diameter so as to be in contact with a surface of the sheathed portion and with the surface of the intermediate anchorage.

This method can further include the step of stripping a sheathing from the tendon in an area adjacent to the intermediate anchorage so as to form the unsheathed portion. One side of the intermediate anchorage has a tubular opening through which the tendon extends. The step of positioning can include sliding the sleeve along the tendon and onto the tubular opening such that the sleeve resides over the sheathed portion and the unsheathed portion of the tendon. The sleeve of the heat shrink material is formed such that the sleeve reduces in diameter but not in length upon the application of heat thereto. The sleeve can be formed so as to have a split between a first longitudinal edge and a second longitudinal edge thereof. The first longitudinal edge can be separated from the second longitudinal edge, and the tendon passed between the longitudinal edge so as to reside on the interior of the sleeve. The first longitudinal edge can then be sealed in overlapping relationship with a surface of the sleeve adjacent to the second longitudinal edge.

In another embodiment of the present invention, the step of positioning can include wrapping a heat shrink material around the sheathed and unsheathed portions of the tendon and the surface of the intermediate anchorage. The heat shrink material is wrapped in overlapping relationship with itself so as to form the sleeve.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is aside elevational view of a post-tensioning system employing the intermediate anchorage of the present invention. [0028]
FIG. 2 is a plan view of the intermediate anchorage system of the present invention. [0029]
FIG. 3 is an isolated front perspective of the sealing apparatus of the present invention. [0030]
FIG. 4 is a cross-sectional view of the intermediate anchorage system of the present invention. [0031]
FIG. 5 is a plan view showing an alternative embodiment of the intermediate anchorage system of the present invention. [0032]
FIG. 6 is a cross-sectional view showing the interior configuration of the alternative embodiment of FIG. 5.[0033]

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, there is shown the [0034] post-tensioning system 10 in accordance with the teachings of the present invention. The post-tensioning system 10 includes a dead end anchor 12, an intermediate anchorage 14 and a live end anchor 16. A tendon 18 extends from the dead end anchor 12 through the intermediate anchorage 14 and onto the live end anchor 16. The dead end anchor 12 is supported on a chair 20 above a slab 22 for a desired distance. The end 24 of the tendon 18 is fixed into the dead end anchor 12. The tendon 18 is a sheathed tendon which extends from the dead end anchor 12 through the intermediate anchorage 14. The intermediate anchorage 14 is mounted on a frame 26 so as to support the intermediate anchorage 14 a desired distance above the floor or slab 22.
The [0035] tendon 18 is initially tensioned in the area between the intermediate anchor 14 and the dead end anchor 12. Suitable wedges are applied into the interior passageway of the intermediate anchor 14 so as to retain the tendon 18 in its stressed condition. The stressed tendon 18 extends through the concrete 18. Prior to the pouring of the concrete 28, a sleeve 30 formed of a heat shrink material is affixed to an end of the anchor 14 on an opposite side of the anchor 14 from the frame 26. Additionally, another heat-shrink tubular corrosion protection sleeve 32 is affixed to the anchor 14 on an opposite side of the frame 26. The corrosion protection sleeve 32 extends over the exposed unsheathed portion of the tendon 18 which extends outwardly into the area between the intermediate anchorage 14 and the live end anchorage 16.
The live end anchor [0036] 16 is mounted on another frame 34 so as to support the live end anchor 16 a desired distance above the floor or slab 22. The end 36 of the tendon 18 will extend outwardly on an opposite side of the frame 34. The end 36 of the tendon 18 can be stressed so as to tension the tendon 18 in the area between the intermediate anchorage 14 and the live end anchor 16. In normal practice, this will cause the exposed portion of the tendon 18 in the area of the intermediate anchorage 14 to extend further outwardly of the intermediate anchorage 14. As such, the tubular corrosion protection sleeve 32 should have a sufficient length so as to accommodate the tensioning of the tendon 18. The tendon 18 extends through the concrete 38 in the area between the intermediate anchorage 14 and the live end anchor 16.
FIG. 2 shows the configuration of the [0037] intermediate anchorage 14 as used in the system of the present invention. The anchor 14 is an encapsulated anchor having a tubular extension 40 extending outwardly from one side of the anchor 14 and a tubular opening 42 extending outwardly from an opposite side of the anchor 14. As can be seen, the tendon 18 extends through the interior passageway of the anchor 14 and through the tubular extension 40 and the tubular opening 42. Importantly, in the present invention, a sleeve 44 of a heat shrink material extends over the exposed unsheathed portion of the tendon 18 adjacent to tubular opening 42. This sleeve 44 includes a split 46 which allows the sleeve 44 to be directly affixed over the tendon 18 and onto the tubular opening 42. The tubular opening 42 is a cap which is received within the anchor 14. The cap 42 has an open end opposite the anchor 14 so as to allow the tendon 18 to extend therethrough. The longitudinal edge 46 of the sleeve 44 can be separated from another longitudinal edge (to be described hereinafter) so as to allow tendon 18 to be easily placed therein. Alternatively, the sleeve 44 can be threaded along the tendon 18 so as to be placed in a proper position over the tubular opening 42. Since the sleeve 44 is of a heat shrink material, heat can be applied to the sleeve 44 so as to reduce the diameter of the sleeve 44 such that the sleeve 44 will reside in liquid-tight sealing relationship with an exterior surface of the tubular opening 42 and the exterior portion of the sheathed portion of the tendon 18. The application of heat should occur after the tendon 18 has been suitably tensioned. A torch or hot air gun can be used so as to effect the heat shrinking of the sleeve 44.
Similarly, another [0038] sleeve 48 can be affixed onto the tubular extension 40 of the anchor 14. This second sleeve 48 will extend over the unsheathed portion of the tendon 18 on the opposite side of the anchor 14. The sleeve 48 will have an end 50 residing over the sheathed portion 52 of the tendon 18. The interior of the sleeve 48 is slidably received onto the outer surface of the tubular extension 40. The relatively long length of the sleeve 48 assures that the exposed portion of the tendon 18 are protected from exposure to the exterior elements. The length of the sleeves 44 and 48 are such as to assure that such protection will continue even through the tendon 18 is tensioned at an opposite end. Importantly, the sleeve 48 can also be heat sealed over the sheathed portion 52 of the tendon 18 and onto the tubular extension 40 of the anchor 14. The sleeve 48 can also be a split sleeve having a split 53 therealong so as to allow the sleeve 48 to be suitably opened and positioned onto the tubular extension 40 and directly over the exposed portions of the tendon 18. Heat can be applied by a torch or hot air gun so as to “heat shrink” the material of the sleeve 53.
Within the concept of the present invention, it is important to realize that the [0039] sleeves 44 and 48 can be solid tubular members. When the sleeves 44 and 48 are not “split” tubular members, they must be threaded along the length of the tendon 18 until they reside in a proper position over the respective surfaces of the anchor 14. Since each of the sleeves 44 and 48 can be formed of a heat shrink material, they can have a much larger diameter than that of the tendon 18 so as to facilitate the ability to slide the sleeves 44 and 48 to their desired positions. In the past, sealing members that had a diameter formed of a dimension matching the outer diameter of the tendon 18 exhibited great difficulty in sliding the tubular sealing members along the length of the tendon 18 to their desired positions. By forming the sleeves 44 and 48 of the “heat shrink” material, larger diameter sleeves can be formed so as to facilitate the threading of the tendon therethrough.
FIG. 3 illustrates the construction of such a split sleeve. FIG. 3 is an illustration of the [0040] sleeve 44 prior to assembly onto the anchor 14. As can be seen, the split sleeve 44 has a first longitudinal edge 54 and a second longitudinal edge 56. Longitudinal edges 54 and 56 are separable by a greater distance than the diameter of the tendon 18 so as to allow the tendon to pass therebetween. The longitudinal edges 54 and 56 extend for the entire length of the sleeve between the first open end 58 and the second open end 60. A suitable adhesive or sealing member can be placed in the area of the overlap between the first longitudinal edge 54 and the second longitudinal edge 56. As such, when the sleeve 44 is placed over the tendon 18, the adhesive can be exposed so as to secure the edges 54 and 56 in overlapping relationship. When heat is applied to the heat shrink material used for the formation of the sleeve 44, the seal between the overlapping edges 54 and 56 will be perfected so as to prevent liquid intrusion therethrough. As such, the present invention avoids mechanical and possible leaking connections between the longitudinal edges 54 and 56.
FIG. 4 shows the manner in which the intermediate anchorage system of the present invention serves to receive the [0041] tendon 18. Initially, it can be seen that the tendon 18 has an unsheathed portion 72 and sheathed portions 74 and 76. The first sleeve 44 is received over the exterior surface of the tubular opening 42 of the anchor 14. The sleeve 44 is illustrated as being “heat shrunk” onto the exterior surface of the tubular opening 42 of the cap 84 associated with the anchor 14. Similarly, the sleeve 44 is heat shrunk so as to be in sealed compressive contact with the sheathed portion 74 of the tendon 18. As such, the unsheathed portion 72 of the tendon 18 will reside in a liquid-tight environment therein. The cap 84 is suitably sealed within the polymeric encapsulation 86 of anchor 14. The tendon 18 is retained in its desired position within anchor 14 through the use of wedges 80.
It can be seen that the [0042] tendon 18 extends through the sleeve 44, through the interior passageway of the anchor 14 and through the interior of the second sleeve 48. Sleeve 48 is shown in its position prior to heat sealing. The sleeve 48 is secured to an exterior surface of the tubular extension 40. The second sleeve 48 extends outwardly so as to have an end extending over the sheathed portion 76 of the tendon 18. When heat is applied to the sleeve 48, it will suitably shrink in diameter so as to establish a heat sealed compressive contact with the exterior surface of the sheathing 76 and with the exterior surface of the tubular extension 40 of anchor 14.
The [0043] sleeves 44 and 48 can be installed in various manners. For example, the sleeves 44 and 48 can be threaded along the length of the tendon 18 until they reach their desired positions relative to the anchor 14. Alternatively, the sleeves 44 and 48 are split sleeves, the split can be suitably opened so that the sleeves 44 and 48 can be directly placed into their desired positions.
FIG. 5 shows an alternative form of the present invention. In the alternative embodiment of the [0044] intermediate anchorage 100, the intermediate anchorage member 102 has sleeve 104 heat sealed directly over the tubular extension 106 and heat sealed onto the sheathing 108 associated with tendon 110. As such, liquid intrusion is effectively prevented into the area of the exposed tendon within the interior of sleeve 104.
In FIG. 5, the opposite side of the [0045] anchor 102 has a cap 112 extending outwardly therefrom. Cap 112 has an opening through which the tendon 110 will pass. Unlike the previous embodiments, the sleeve 114 will be a heat shrink material which is wrapped around the exterior surface of the cap 112, over the exposed portions of the tendon 110 and over the sheathing 116 associated with tendon 110. After being wrapped around the tendon 110, in the manner shown in FIG. 5, heat can be applied to the sleeve 114 so as to reduce the diameter of the sleeve 114 and to establish a liquid-tight sealing contact between the sheathing 116 of tendon 110 and the exterior surface of the cap 112.
FIG. 6 shows how the [0046] sleeve 104 is directly installed onto the tubular extension 106 of anchor 102. The tubular extension 106 of anchor 102 is formed in the encapsulation 120 of the anchor 102. A snap-fit projection 122 extends outwardly of the tubular extension 106. The sleeve 104 has a complementary female fitting 126 which engages the shoulder of the projection 122. As such, the sleeve 104 can be threaded along the lengths of the tendon 110 until the end is snap-fit into the position shown in FIG. 6. The sleeve 104 will extend over the exposed portion 128 of the tendon 110. The opposite end 130 of the sleeve 104 will reside over the sheathed portion 108 of tendon 110. When heat is applied to the sleeve 104, it will suitably shrink in diameter, but no in length since the sleeve 104 is formed of uniaxially shrinkable material. As such, the surfaces of the sleeve 104 will establish a strong compressive sealing contact with the sheathing 108 of tendon 110. Similarly, the sleeve 104 will establish a strong sealing contact with the tubular extension 106 of the anchor 102.
The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the true spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents. [0047]

Claims

I claim:

1. An intermediate anchorage for a post-tension system comprising:

an anchor member having an interior passageway extending therethrough;

a tendon extending through said interior passageway of said anchor, said tendon having a sheathed portion and an unsheathed portion extending outwardly from at least one side of said anchor member; and

a first sleeve formed of a heat shrink material, said first sleeve received at one end by said anchor member and extending over said unsheathed portion of said tendon extending outwardly of said anchor, said first sleeve having another end extending over said sheathed portion of said tendon, said first sleeve being in heat sealed compressive contact with a surface of said anchor and with an exterior surface of said sheathed portion.

2. The anchorage of claim 1, said anchor having a tubular member extending outwardly therefrom, said first sleeve being in heat sealed compressive contact with said tubular member of said anchor.

3. The anchorage of claim 1, said tendon having a sheathed portion and an unsheathed portion extending outwardly from an opposite side of said anchor member, the anchorage further comprising:

a second sleeve formed of a heat shrink material, said second sleeve extending over said unsheathed portion of said tendon extending outwardly from said opposite side of said anchor member, said second sleeve being in heat sealed compressive contact with a surface of said anchor member and with an exterior surface of said sheathed portion of said tendon extending outwardly from said opposite side.

4. The anchorage of claim 3, said anchor member having a cap affixed thereto and extending outwardly therefrom, said cap having an opening through which said tendon passes, said second sleeve being in heat sealed compressive contact with an exterior surface of said cap.

5. The anchorage of claim 1, said first sleeve being in liquid-tight relationship with said surface of said anchor member and with said sheathed portion of said tendon.

6. The anchorage of claim 3, said second sleeve being in liquid-tight relationship with said surface of said anchor member and with said exterior surface of said sheathed portion of said tendon.

7. The anchorage of claim 1, said first sleeve being a split tubular member having a single split extending longitudinally therealong, said split tubular member having a sealing means formed for joining edges of said split tubular member together around said sheathed and said unsheathed portions of said tendon.

8. The anchorage of claim 7, said single split of said split tubular member having a first longitudinal edge and a second longitudinal edge, said first longitudinal edge being in overlapping relationship with an exterior surface of said split tubular member adjacent said second longitudinal edge of said split tubular member.

9. The anchorage of claim 1, said first sleeve being a wrapping wrapped around said unsheathed portion and said sheathed portion and the surface of said anchor member.

10. The anchorage of claim 1, said anchor member being an encapsulated anchor having a tubular extension extending outwardly from one side of said anchor member, said tendon extending through said tubular extension, said one end of said first sleeve being affixed in heat sealed liquid-tight relationship with said tubular extension.

11. A method of sealing an intermediate anchorage in a post-tension system comprising:

extending a tendon through an interior passageway of the intermediate anchorage;

stressing said tendon such that an unsheathed portion of said tendon extends outwardly of one side of the intermediate anchorage;

positioning a sleeve over a sheathed portion of said tendon and over said unsheathed portion of said tendon and over a surface of said intermediate anchorage; and

heating said sleeve such that said sleeve reduces in diameter so as to be in contact with a surface of said sheathed portion and said surface of said intermediate anchorage.

12. The method of claim 11, further comprising the step of:

stripping a sheathing from said tendon in an area adjacent said intermediate anchorage so as to form said unsheathed portion.

13. The method of claim 11, said one side of said intermediate anchorage having a tubular opening through which said tendon extends, the step of positioning further comprising the step of:

sliding said sleeve along said tendon and onto said tubular opening such that said sleeve resides over said sheathed portion and said unsheathed portion of said tendon.

14. The method of claim 13, further comprising the step of:

forming a sleeve of a heat shrink material such that said sleeve reduces in diameter but not in length upon the application of heat thereto.

15. The method of claim 14, said step of forming said sleeve comprising:

forming said sleeve so as to have a split between a first longitudinal edge and a second longitudinal edge thereof.

16. The method of claim 15, said step of positioning comprising:

separating said first longitudinal edge from said second longitudinal edge; and

sliding said tendon between said first longitudinal edge and said second longitudinal edge such that said unsheathed portion resides interior of said sleeve.

17. The method of claim 16, said step of positioning further comprising:

sealing said first longitudinal edge in overlapping relationship with a surface of said sleeve adjacent said second longitudinal edge.

18. The method of claim 11, said step of positioning comprising:

wrapping a heat shrink material around said sheathed portion and said unsheathed portion and said surface of said intermediate anchorage, said heat shrink material being wrapped in overlapping relationship so as to form said sleeve.

19. The method of claim 18, said step of stressing comprising the step of stressing said tendon such that said unsheathed portion extends outwardly at an opposite end of said intermediate anchorage, the method further comprising the steps of:

positioning another sleeve over another surface of said intermediate anchorage and over said unsheathed portion; and

heat sealing said another sleeve onto another sheathed portion of said tendon and onto said another surface of said intermediate anchorage.

20. The method of claim 19, further comprising the step of:

forming said intermediate anchorage so as to have a cap member affixed thereto, said tendon extending through said cap member, said another surface of said intermediate anchorage being a surface of said cap.