SEALING CAP FOR TENSILE ELEMENTS

Description

BACKGROUND

The present disclosure relates generally to sealing caps for tensile elements and installation of sealing caps for tensile element enclosures, the tensile element enclosure being any combination of a tensile element, an anchor, and at least one clamping device. The sealing caps improve the bond between the tensile element enclosures and the surrounding substrate and reduce the risk of corrosion.

Prestressed concrete is a form of concrete used in construction, where the concrete is prestressed (e.g., compressed) during production such that the concrete is strengthened against tensile forces or stresses that will exist when the concrete is in use. The prestressing is produced by the tensioning of high-strength tensile elements located within or adjacent to the concrete. Prestressed concrete has the characteristics of high-strength concrete when subject to any subsequent compression forces and of ductile high-strength steel when subject to tension forces. Thus, prestressed concrete has improved structural capacity and/or serviceability compared with conventionally reinforced concrete.

Post-tensioning is one type of prestressing where high-strength tensile elements (e.g., steel cables and bars, glass, fiber-reinforced polymer (FRP) composites, and the like) are placed before the concrete is cast. Then, after the concrete is cast and has gained strength, but typically before service loads are applied, the tensile elements are pulled tight (i.e., tensioned) and anchored against the edges of the concrete (e.g., an outer edge or an edge in the middle of a slab). Post-tensioning may be carried out via monostrand systems, where each tensile element is placed and stressed individually, or via multi-strand systems, where several tensile elements are placed in a single conduit and where stressing can be done individually or simultaneously for the group.

The tensile element tail extends beyond an anchorage used to stress the tensile element. After stressing the tensile element may be cut to reduce the length of the tensile element tail. A sealing cap is then placed over the tensile element tail in order to create an air or water-tight enclosure surrounding the tensile element tail. The sealing cap may be placed over tensile element tails that are either tensioned or which remain un-tensioned. Filling material is then disposed over the sealing cap and then formed to conform to the surrounding substrate, thereby sealing the sealing cap within the post-tensioned substrate or concrete.

Many sealing caps that are designed to encompass a single tensile element include substantially flat outer surfaces, while sealing caps configured to encompass multiple tensile elements may include a larger, substantially round or dome-like structure or an outer surface which is substantially box-shaped. In either instance, the outer surfaces of each sealing cap are substantially smooth and as a result offer a minimum surface area which may bond to a surrounding substrate.

However, in post-tensioning applications, despite the use of a sealing cap, water intrusion can result from not properly encasing the tail of the tendon. Best practices where steel strands constitute the tensile elements dictate that the tensile element tail should be cut between ½″-¾″ from the anchorage. If the tensile element tail is too long, traditional sealing caps cannot be seated properly, allowing water to seep through surrounding filling encompassing the sealing cap of the tensile element tail and cause corrosion. Dislodging of the surrounding filling material will also allow water to intrude into the anchorage over time, allowing the tensile element tail to rust and corrode.

Improvement of the bonding between the sealing cap to the surrounding filling material may overcome one or more of the aforementioned problems. Therefore, it may be desirable to provide an optimal sealing cap which has improved bonding properties, thereby creating a better seal for the anchorage and preventing unwanted rust and corrosion of the tensile element tail and possible structural failure of the surrounding substrate.

SUMMARY

According to various embodiments, a sealing cap is provided, the sealing cap including a body, wherein the body itself includes an outer surface and an inner surface, the inner surface defining an enclosure and at least one protrusion extending from the outer surface. The protrusion may be configured to engage with a filling material when disposed around the sealing cap and may include at least one aperture that is defined in a surface of the protrusion. The enclosure of the sealing cap may be filled with a protective filler. In certain embodiments, the protrusion is concentric relative to a longitudinal axis of the body and may include a hollow volume that is defined therein. A vent may be defined through the body of the sealing cap, wherein the vent provides fluidic access to the enclosure.

According to certain embodiments, a method of installing a sealing cap is provided. The method includes inserting the sealing cap into a void defined within a substate, the void having at least one tensile element tail protruding through an anchor. The sealing cap may cover the tensile element tail with the sealing cap and be coupled to the anchor. The void within the substrate around the sealing cap is then encompassed by a filling material which engages with a protrusion extending from an outer surface of the sealing cap. According to various embodiments, the method also includes distributing a protective filler into the sealing cap either before or after the sealing cap is encompassed by the filling material. Encompassing the sealing cap with a filling material may specifically include disposing the filling material through at least one aperture defined through the protrusion, or disposing the filling material into a hollow volume defined by a surface of the protrusion. Engaging the filling material with the protrusion that extends from the outer surface of the sealing cap may specifically include engaging the filling material to a surface of the aperture, or engaging the filling material to a surface of the protrusion that is concentrically disposed relative to a body of the sealing cap. Covering the at least one tensile element tail with the sealing cap may specifically include covering a clamping device on the at least one tensile element tail with the sealing cap, covering a plurality of tensile element tails and a plurality of clamping devices with the sealing cap, or covering at least one clamping device and the anchor with the sealing cap.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be further described, by way of example only, and with reference to the accompanying drawings, in which:

FIG. 1A illustrates a perspective view of a sealing cap configured for a single tensile element, according to an embodiment.

FIG. 1B illustrates a perspective view of a sealing cap configured for multiple tensile elements, according to an embodiment.

FIG. 2A illustrates a side cross sectional view of an anchorage including a pocket former before a substrate is applied, according to an embodiment.

FIG. 2B illustrates a side cross sectional view of an anchorage including a sealing cap inserted into a void after a substrate is applied, according to an embodiment.

FIG. 2C illustrates a perspective partially-transparent view of an anchorage including an sealing cap inserted into a void after a substrate is applied, according to an embodiment.

FIG. 3 illustrates a perspective view of an anchorage with multiple tensile elements threaded therethrough, according to an embodiment.

FIG. 4 illustrates a perspective view of stressing equipment stressing a tensile element threaded through an anchorage, according to an embodiment.

FIG. 5 illustrates a perspective view of a tensile element tail threaded through a clamping device, according to an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1A illustrates an exemplary embodiment of a sealing cap 100, the sealing cap 100 being configured to cover or otherwise accommodate a single tensile element tail. The sealing cap 100 includes a body 102 having a longitudinal axis 112 formed by an outer surface 104 and an inner surface, the inner surface defining a tensile element enclosure that is configured to accommodate at least one tensile element tail therein. According to certain embodiments, the body 102 may be formed from a polymer, reinforced polymer, or polymer composite. A base 106 at a distal end 108 of the sealing cap 100 is configured to engage with the anchorage through a mechanical interlocking fixture, a friction-based interlocking fixture, or a combination thereof and includes an opening for the tensile element tail to be inserted therein. A proximal end 110 of the sealing cap 100 may include a protrusion 114 which extends from the outer surface 104 of the body 102. According to certain embodiments, the protrusion 114 may extend from the outer surface 104 along or parallel relative to the longitudinal axis 112 of the body 102, however in other embodiments the protrusion 114 may extend radially from the longitudinal axis 112 or at any relative angle therebetween. Additionally, the protrusion 114 as seen in FIG. 1A may be symmetric or concentrically disposed relative to the longitudinal axis 112 of the body 102, however in alternative embodiments the protrusion 114 may be asymmetric and only disposed on one specific side or portion of the body 102. The protrusion 114 may include a height and have a substantially annular cross section with a hollow volume 116 defined therein. The hollow volume 116 is open to the surrounding environment to allow incoming filling material therein. According to certain embodiments, the protrusion 114 includes a plurality of openings or apertures 118 defined within a surface of the protrusion 114 itself. The apertures 118 seen in FIG. 1A are substantially circular in shape, however in certain other embodiments other shapes may be used. In an alternative embodiment, the protrusion 114 may instead have a smooth, continuous surface or alternatively may include at least one profile which extends or projects away from the protrusion 114 and/or the outer surface 104.

FIG. 1B illustrates an exemplary embodiment of a sealing cap 150, the sealing cap 150 being configured to accommodate, cover, or otherwise accommodate multiple tensile element tails. The sealing cap 150 includes a body 152 having a longitudinal axis 162 formed by an outer surface 154 and an inner surface, the inner surface defining a tensile element enclosure that is configured to accommodate the tensile element tails therein as detailed further below. According to certain embodiments, the body 152 may be formed from a polymer, steel, or a combination thereof. A base 156 at a distal end 158 of the sealing cap 150 is configured to engage with the anchorage through an interlocking fixture, a friction-based interlocking fixture, or a combination thereof and includes an opening for the tensile element tails to fit inside the sealing cap 150. A proximal end 160 of the sealing cap 150 may include a protrusion 164 which extends from the outer surface 154 of the body 152. According to certain embodiments, the protrusion 164 may extend from the outer surface 154 along the longitudinal axis 162 of the body 152, however in other embodiments the protrusion 164 may extend radially from the longitudinal axis 162 or at any relative angle therebetween. Additionally, the protrusion 164 as seen in FIG. 1B may be symmetric or be concentrically disposed relative to the longitudinal axis 162 of the body 152, however in alternative embodiments the protrusion 164 may be asymmetric and only disposed on one specific side or portion of the body 152. The protrusion 164 may include a height and have a substantially annular cross section with a hollow volume 166 defined therein. The hollow volume 166 is open to the surrounding environment to allow filling material therein. According to certain embodiments, the protrusion 164 includes a plurality of openings or apertures 168 defined within a surface of the protrusion 164 itself. The apertures 168 in FIG. 1B are seen as elongated cylinders or substantially obround in shape, however in certain other embodiments other shapes may be used. In an alternative embodiment, the protrusion 164 may instead have a smooth, continuous surface or alternatively may include at least one profile which extends or projects away from the protrusion 164 and/or the outer surface 154.

According to certain embodiments, the sealing cap 100, 150 includes a protective material or substance that may be coated on or around the body 102, 152 of the sealing cap 100, 150, thereby protecting the sealing cap 100, 150 from moisture or other elements within the surrounding environment. Additionally, the sealing cap 100, 150 may further include additional accessories which assist in sealing the sealing cap 100, 150 when a pumping pressure is applied during the filling process.

Additionally, it should be noted that while the sealing cap 100, 150 is described as having a protrusion 114, 164 extending therefrom, a variety of other physical features may be included according to certain embodiments. For example, the sealing cap 100, 150 may include any number or combination of flanges, fins, profiles, projections, protuberances, sub-protrusions or any other feature which may be suitable to interact or engage with a filling material as described in further detail below.

FIGS. 2A-2C illustrate how the sealing cap 202 is installed or coupled to an anchorage used to post-tension at least one tensile element 204. FIG. 2A specifically illustrates a post-tensioning anchorage zone 200 in an initial or set-up configuration before a substrate is cast. According to certain embodiments, one or more tensile elements 204 are threaded through a voided path, such a duct or enclosure 230 which in turn may be disposed in a formwork 216. According to certain embodiments, the tensile element may include a metal cable, bar, or other structural element. A stressing anchor 206 may be placed into the anchorage zone 200 followed by a pocket former 210. According to certain other embodiments, the pocket former 210 may be placed before the stressing anchor 206, or alternatively, both the pocket former 210 and the stressing anchor 206 may be placed before the tensile element 204 is threaded through the anchorage zone 200.

According to certain embodiments, for example as seen in FIG. 3, an excess length 302 of the tensile elements are left protruding or extending outside the anchor 300. The specific amount of excess length may be based on the type of stressing equipment used, however according to some embodiments, each tensile element may extend 0.1-36 inches outside of the anchorage 300.

Returning to FIGS. 2B and 2C, a substrate 212 may be cast into the formwork 216 and around the anchorage zone 200 and then left to cure. According to certain embodiments, the substrate 212 may be concrete or other building material. The pocket former 210 may then be removed, thereby leaving a void or stressing pocket 214 in its place as seen in FIGS. 2B and 2C. A clamping device 208 may then be placed into the stressing pocket 214 for each tensile element 204 disposed therein. According to certain embodiments, the clamping device 208 may include a wedge, a nut, or other like element. The stressing pocket 214 permits access for stressing equipment, for example a stressing jack, to be coupled to the one or more tensile elements 204.

The tensile elements 204 may be stressed together simultaneously using multi-element stressing equipment, or one-by one via single-element stressing equipment. For example, as seen in FIG. 4, a stressing jack 400 may be inserted into a stressing pocket 402 defined within a substrate 406 that is configured to apply tension to a single tensile element 404 extending therefrom.

Once the tensioning process has been completed and approved, the excess length of each of the tensile elements 204 which protrude out of the anchorage zone 200 is cut, leaving a relatively short tensile element tail 218 protruding outside the anchorage zone 200 and into the stressing pocket 214. According to certain embodiments, for example as seen in FIG. 5, each tensile element tail 500 may extend 0.1-10 inches from the clamping device 502 while directly opposing the enclosure 504 for the tensile element.

In certain embodiments and returning to FIGS. 2A-2C, the sealing cap 202 is inserted into the stressing pocket 214 to cover a tensile element tail 218 as seen in broken line drawing in FIG. 2B. According to certain embodiments, if one tensile element tail 218 is disposed within the stressing pocket 214, the single-tail sealing cap 100, FIG. 1A may be used, while if multiple tensile element tails 218 are disposed within the stressing pocket 214, the larger multi-tail sealing cap 150, FIG. 1B may be used to cover all the tensile element tails 218 simultaneously. In certain embodiments, as the sealing cap 202 covers the one or more tensile element tails 218, the sealing cap 202 may also cover the anchor 208 at the same time. The sealing cap 202 may be coupled to the anchor 208 or the surrounding formwork 216 through an interlocking fixture 224 disposed a distal portion of the sealing cap 202, according to certain embodiments.

Once the sealing cap 202 is installed, a protective filler may be distributed through the stressing pocket 214 and into the internal tensile element enclosure 220 defined by the sealing cap 202. According to certain embodiments, the protective filler may be an anti-corrosion filler. The sealing cap 100, 150 may include a vent or other channel configured to provide fluidic communication between the surrounding environment and the internal tensile element enclosure 220. For example, as seen in FIG. 1B, a vent 170 may be defined through a portion of the protrusion 164 or other part of the outer surface 154 of the sealing cap 150, the vent 170 providing direct, fluidic access to the tensile element enclosure 220 and thereby allowing the protective filler to be poured, injected, pumped, or otherwise dispensed directly therein. In an alternative embodiment, the protective filler may be pre-filled or pre-distributed within the tensile element enclosure 220 of the sealing cap 202 before the sealing cap 202 is used to cover the one or more tensile element tails 218. The distributed protective filler is allowed to surround the one more tensile element tails 218, thereby providing a protective layer between each tensile element tail 218 and the surrounding environment. According to certain embodiments, the protective filler may include grout, wax, grease, or the like.

As further seen in FIG. 2B, a patching or filling material 222 may be distributed into the stressing pocket 214. As the stressing pocket 214 is filled, the filling material 222 encompasses or envelops the sealing cap 202 and surrounds the entirety of the protrusion 226 by filling into the hollow volume 116, FIGS. 1A, 166, FIG. 1B defined therein and making contact with each of the surfaces or features which define the protrusion 226. According to certain embodiments, the filling material 222 may traverse a surface of the protrusion 226 by entering and flowing through at least one aperture 228 defined in the protrusion 226. As the filling material 222 is cured, the filling material 222 bonds to the various surfaces of the protrusion 226 including those of the apertures 228, thereby forming a tight connection or lock between it and the sealing cap 202 as a whole. According to certain embodiments, by distributing the filling material 222 between and amongst the multiple surfaces of the protrusion 226, including the inner surfaces of the apertures 228, an extremely robust interlocking connection or coupling is formed between the sealing cap 202 and the filling material 222. Providing a tight lock or bond between the sealing cap 202 and the filling material 222 leads to less risk of corrosion to the tensile element tails 218 and less risk of the filling material 222 popping or dislodging outside its enclosure or surrounding substrate 212, for example due to shrinkage.

Additional embodiments include any one of the embodiments described above, where one or more of its components, functionalities, or structures is interchanged with, replaced by or augmented by one or more of the components, functionalities, or structures of a different embodiment described above.

Although several embodiments of the disclosure have been disclosed in the foregoing specification, it is understood by those skilled in the art that many modifications and other embodiments of the disclosure will come to mind to which the disclosure pertains, having the benefit of the teaching presented in the foregoing description and associated drawings. It is thus understood that the disclosure is not limited to the specific embodiments disclosed herein above, and that many modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although specific terms are employed herein, as well as in the claims which follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the present disclosure, nor the claims which follow.