POST-TENSIONING APPARATUS AND SYSTEM FOR STRUCTURES

Abstract

The present invention pertains in general to post-tensioning apparatus and systems surrounding the fabrication and repair of concrete and other construction materials. The present invention surrounds apparatus and system directed to the post-tensioning for reinforcement of existing and new concrete structures through the application of tensile forces between two attachment points anchored to the structure to be mended.

Description

CROSS REFERENCE TO REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application 62/253,681 entitled “Post-Tensioning Apparatus and System for Structures” filed on Nov. 11, 2015, the entire contents of which are incorporated herein by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The present invention pertains in general to post-tensioning apparatus and systems surrounding the fabrication and repair of concrete and other construction materials. The present invention surrounds apparatus and system directed to the post-tensioning for reinforcement of existing and new concrete structures through the application of tensile forces between two attachment points anchored to the structure to be mended.

BACKGROUND OF THE INVENTION

The field of concrete installation and maintenance, particularly surrounding structural or load bearing concrete, requires site preparation and formula of mix to create the desired preparation. Although mechanically strong in compression, concrete is relatively weak in tensile and bending loads and is subject to cracking and breakage under such conditions.

Practices including techniques of post-tensioning, which involves the pre-stressing of steel tendons within the concrete form to account for its relative weakness in tension. This practice is often used in installation for purposes such as commercial and residential construction where beams, floors and bridging components must span a length exceeding longer than practical with ordinary reinforced concrete.

Although the practice of post-tensioning aims to pre-load concrete and place it under a resting compressive load to counteract tensile and bending loads to mitigate mechanical failures. However, uncontrollable variables such as frost heaving, ground movement, erosion, water infiltration and others compromise the structural integrity of concrete and can cause cracking and mechanical failure of the structure of the concrete installation.

Due to the costly or nature or logistical impossibility of the replacement of concrete installations, many solutions aim to repair concrete after mechanical failure. Although it may seem sensible to replace a concrete installation in some situations, it will be appreciated that even the wholesale demolition and reinstallation of the concrete may not guarantee against failure in the future.

Cracks in concrete are caused due to the mechanical failure of the concrete in a localized area due to a possible variety of problems with the installation. For this reason, tensioning may be desired in scenarios such as the cross-linking of independently poured concrete installations or providing tension in “post-tensioning” to repair a concrete installation using tensile strengthening features. The application of metal structure for the tensile reinforcement is typically placed across a mechanical failure zone such as a fissure or crack where the concrete installation has mechanically failed. Post-tensioning typically involves preloading of a metal structure prior to adding more concrete to reinforce the repair.

SUMMARY OF THE INVENTION

Some solutions aim to fill the crack with a bonding adhesive or cement to repair the concrete. However, the lack of strength afforded by cements, often referred to as hydraulic cement, proves problematic. When considering the structural integrity of a concrete installation, the cost of repeated failure depends upon the application of the concrete. And cement patches have a high risk of repeated failure due to weak bond and structural integrity of the cement.

Other solutions to the mechanical failure of concrete resulting in cracks is addressed through internal metal stitching as proposed by U.S. Pat. No. 5,476,340, ('340), and U.S. Pat. No. 5,771,557, ('557), incorporated herein by reference, to Contrasto. Constrasto '340 discloses a method surrounding the use of apparatus '557 to bridge a crack using a series of cuts across a crack, inserting metal structure, and making additional cuts across the previous cuts and metal structure to add cross structure in the form of metal brackets prior to the addition of filler material. Contrasto '340 fails to provide any method of tension application to the concrete.

Constrasto '557 aims to provide increased localized tensile strength for the concrete around a crack. The higher ductility of steel as compared to concrete does not prevent the movement of the concrete beyond a failure threshold and therefore cannot prevent further cracking in the localized region and Contrastro '557 fails to provide the ability to pre-tension the structure or provide post-tensioning to the concrete structure.

Some solutions aim to address failed concrete by placing devices across cracks due to mechanical failure in efforts to provide post-tensioning by preloading metal members spanning across the crack. These metal members comprise plates with a post at either distal end affixed to one side that are inserted into pre-drilled apertures for anchoring. The metal members are then tensioned using wedge or cam based mechanisms to tension the metal member after the posts have been inserted into the concrete. These tensioning mechanisms, however, are limited in travel. If the apertures created for the posts are spaced too far apart, the user may not be able to install the metal member. If the apertures created for the posts are too close together, the user may not be able to tension the metal member as prescribed.

The present invention relates to a post-tensioning apparatus and system providing functionality of post-tensioning to existing structures. The present disclosure relates to the repair of concrete structures but is not limited to such application. Embodiments of the invention permit the application and adjustment of a modular post-tensioning apparatus including at least two attachment features interconnected by at least one tensioning mechanism. The modularity of the apparatus surrounds the ability to select and use different attachment features based upon the location, substrate, desired tensioning properties and other relevant variables in the tensioning of a structure.

In certain embodiments of the present invention, a modular apparatus and system provides tension to existing structures, such as an existing concrete installation, where it is desired to provide post structural reinforcement.

Embodiments of the apparatus provide tensile strength across a mechanical failure zone without further tensioning of the apparatus. However, tensioning the apparatus preloads the apparatus to resolve tolerances or gaps between the apparatus and the points of application within a structure to which it is applied. Tensioning the apparatus also places the apparatus in tension and compresses the structure between attachment features applied to the structure. This also mitigates tensile forces bearing on the concrete, as concrete is typically weaker in tension than in compression.

Certain embodiments of the present invention comprise at least two tension application components interconnected by one tensioning mechanism. Once the tension application components are applied to the structure, the tensioning mechanism is actuated to apply a tensile load to the tension application components, placing the apparatus in a tensile state.

Tension application components translate forces from the tensioning mechanism to the structure by attaching to the structure, such as a concrete installation. Each tension application component may also be attached to one or more application points. These application points may be on a singular structure or spanning two separate structures. It will be appreciated that the tension application components may comprise a variety of forms including, but not limited to, a post-like device, hook, loop and/or plate with attachment features for attachment to a structure. In certain embodiments, the apparatus permits modular use of a variety of tension application components where the apparatus may be used with two tension application devices of similar or dissimilar size, shape or form. It will be further appreciated that application points may comprise apertures in the structure, other features within the concrete or hardware pre-affixed to the concrete.

In certain embodiments, a tensioning mechanism comprising two axially aligned threaded female features, one having standard clockwise threading and the opposing exhibiting counter-clockwise threading, is referred to as a turnbuckle. In such an embodiment, the tension application components have a cylindrical cross-section with a length of screw threading at a proximal end to engage with the threaded female features of the tensioning mechanism. Furthermore, the distal section of the tension application component has as bend, which provides a post-like form to allow the application of force upon an existing structure. A structure may also be prepared by creating an aperture in the structure where one can place the tension application component to apply force on the structure.

It will be appreciated that a tensioning mechanism may comprise a turnbuckle. The tensioning mechanism may also comprise a rotational device with a set of indexed features radially around the rotational device in which a pawl, cog, or tooth engages to allow motion in one direction only, such as a ratchet, or a geared mechanism such as a rack-and-pinion or worm gear.

Certain embodiments of the present invention are directed to the repair of a concrete structure where a fissure or crack has occurred. The surface is prepared by creating plurality of apertures with at least one aperture being on a first side of a fissure or crack, and at least one aperture being on a second side of a fissure or crack. The apertures are positioned at a distance that generally corresponds to the length of the apparatus prior to actuation of the tensioning mechanism which shortens the apparatus. The distal ends of first and second tension application components are then inserted into the corresponding apertures of the prepared surface. Tension can then be applied by actuating the tensioning mechanism, creating post-tensioning in the area surrounding the crack or fissure.

In certain embodiments, a tension application component is used to apply a tensile load across a portion of a structure. The tension application component comprises an attachment end configured to engage with a tensioning mechanism. The attachment end engages the tensioning mechanism at a proximal end of the tensioning application component. The distal end of the tension application component has a feature such as an aperture or hook-form configured to engage with features installed in the structure. Such features which include, but are not limited to a post or rebar affixed to the structure.

Certain embodiments of the present invention comprise a tensioning application component that engages with the tensioning mechanism. The proximal end of the tension application component has an attachment feature configured to engage with the tensioning mechanism. The distal end of the tension application component is configured to engage the apertures within a prepared surface or extents of an existing structure with a plurality of post-like features. Having a plurality of post-like features distributes the load of the tensioning apparatus across a larger area. The distribution of forces allows the installation of a post-tensioning apparatus with structures having limited structural stability rather than an apparatus with a more concentrated loading which may risk further damage to the structure to be repaired. A scenario in which a user may want to use more than one post-tensioning apparatus, the plurality of post-like features allows the use of fewer post-tensioning apparatuses over a given length of a fissure or crack to achieve stronger structural stability.

Certain embodiments have a tension application component. In certain embodiments, the tension application component comprises a plate-form. The plate-form affixes to a structure to apply tensile load to the structure at the desired location. The plate-form can be affixed by welding or using at least one threaded fastener, masonry anchor or other methods known to those skilled in the art. The plate-form may further comprise a fixation point such as a loop or hook to allow the engagement of a tension application component. It may be desired to affix the plate-form to the structure using a plurality of fasteners or anchors to distribute tensile loading across a larger area of concentration on the structure. This distributed loading can also provide tensile strength between independent structures where other types of tension application components cannot. In contrast, post-like forms create a higher localized concentration of stress. Furthermore, the use of plate-forms may allow the post-tensioning between adjacent structures that are not coplanar such as adjacent planar structures disposed at not offer the necessary structural stability to provide tension between independent structures.

In certain embodiments, a tension application component has a plate-form having at least one aperture. The tension application component includes an engagement feature extending outward from the surface of the plate-form. The engagement features can engage with a tensioning mechanism, including through the use of a threaded male component, the threaded male component typically being axially parallel to the bore of the aperture in the plate-form. In such an embodiment, a tension application component can be attached to a first surface at an angle, typically orthogonal, and attached to a second surface. This allows post-tensioning across a crack or fissured that has occurred proximal to a corner where two sections of a structure meet at an angle.

Certain embodiments of the present invention comprise a tension application component having at least two parallel post structures. The two parallel post structures are disposed at an angle from a connecting body. The tension application component has an aperture, located medial to the post structures. The aperture is also typically axially parallel to the post structures. The tension application component distributes the load applied to the structure and provides a post-tensioning effect to a larger area. In certain embodiments, the tension application component has a post feature attached to a tensioning mechanism, where the post feature is disposed through the medially located aperture.

In certain embodiments of the invention, the apparatus comprises a tensioning mechanism having a consistent cross-sectional profile. The tensioning mechanism can have female threaded features at its distal ends. The threaded receptacles have opposing threading direction. Thus, when engaged with rotationally constrained male threaded features, the opposite threading direction allows both male threaded features to be drawn toward the center of the tensioning mechanism when rotated in a first direction and forces the male threaded features away from center when rotated a second direction, opposite the first direction. Alternatively, it will be appreciated that the tensioning mechanism may have male threaded features and the tension application components have female threaded features.

In certain embodiments, the tensioning mechanism has a torque application feature. The torque application feature actuates the tensioning mechanism by applying rotational forces to tension application components. The torque application feature may have different individual forms or a combination of forms as known to those skilled in the art. The profile of the tensioning mechanism may have forms including but not limited to elliptical, circular, hexagonal, octagonal or square.

In certain embodiments, the external profile of the tensioning device has a form with parallel exterior surfaces, such as a square, hexagonal or octagonal form. The external profile may be used for the application of torque with a tool such as a wrench or other standard torque applying tool.

In certain embodiments, the tensioning mechanism has at least one aperture. The aperture passes through the tensioning mechanism perpendicular to central axis of the mechanism typically intersecting the central axis. The aperture allows for torque application through the use of a rod or other shaft-like object inserted into the aperture. After torque application it may be desired to dispose a rod in the aperture to prevent counter-rotation by engaging the rod with the structure, such as concrete, to which an apparatus comprising a tensioning mechanism is applied. It will be appreciated by those skilled in the art that such apertures are typically in a medial section of the tensioning mechanism. Furthermore, it may be desired to have a plurality of apertures. The additional apertures can be angularly displaced from other apertures such as on 45-degree or 90-degree increments that allow for easier adjustment of the tensioning mechanism in tighter locations. The apertures may be coplanar to the axis of the central axis. In certain embodiments, the apertures may be located on offset yet parallel planes that are perpendicular to the central axis of the tensioning mechanism.

Embodiments of the present disclosure may be used in a system comprising at least one tensioning mechanism and at least two tension application components. Furthermore, different tensioning components may be used interchangeably with a tensioning mechanism to allow system customization for each application.

BRIEF DESCRIPTION OF FIGURES

FIG. 1A—A top view of a post tensioning system

FIG. 1B—A side view of a post tensioning system

FIG. 2—A side view of a turnbuckle embodiment of a tensioning mechanism

FIG. 3—A side view of a tension application component

FIG. 4A—A side view of a tension application component

FIG. 4B—A top view of a tension application component

FIG. 5A—A top view of a post tensioning system

FIG. 5B—A side view of a post tensioning system

FIG. 6A—A perspective view of a tension application component

FIG. 6B—A top view of a tension application component

FIG. 6C—A side view of a tension application component

FIG. 7A—A top view of a post tensioning system

FIG. 7B—A side view of a post tensioning system

FIG. 8A—A bottom view of a tension application component

FIG. 8B—A side view of a tension application component

FIG. 8C—A top view of a tension application component

FIG. 9A—A perspective view of a post tensioning system

FIG. 9B—A side view of a post tensioning system

FIG. 9C—A front view of a post tensioning system

FIG. 10A—A side view of a tension application component

FIG. 10B—A top view of a tension application component

FIG. 11—A perspective view of a tension application component

DETAILED DESCRIPTION

In certain embodiments of the present invention, a modular apparatus and system provides tension to existing structures, such as an existing concrete installation, wherein it is desired to provide structural reinforcement. Tensioning may be desired in many scenarios such as the cross-linking of independently poured concrete installations or providing tension in “post-tensioning” to repair a concrete installation using tensile strengthening features. The application of metal structure for the tensile reinforcement is typically placed across a mechanical failure zone such as a fissure or crack where the concrete installation has mechanically failed.

An apparatus 100, as shown in FIGS. 1A and 1B, embodying the inventive principles of the invention comprises at least two tension application components 101a and 101b and one tensioning mechanism 102 disposed and attached therebetween. When the tension application components 101 are constrained, the actuation of the tensioning mechanism 102 applies tensile force to the tension application components 101 resulting in placing the apparatus in a tensile state. Certain embodiments of such an apparatus may comprise an overall length of 30.5 cm (12 in).

The tension application component 101 translates forces from the tensioning mechanism 102 to the structure by attaching to a structure, such as a concrete installation. The tension application component 101 may also be attached to two or more independent elements or structures. It will be appreciated that the tension application components 101 may comprise a variety of forms including, but not limited to, a post-like device, hook, loop and/or plate with attachment features for attachment to a structure. In certain embodiments the apparatus 100 permits modular use of a variety of tension application components wherein the apparatus may be used with two tension application devices of similar or dissimilar size, shape or form.

In certain embodiments of the apparatus, as shown in FIG. 2, a tensioning mechanism 102 comprises two axially aligned threaded female features, 201a and 201b, having opposing threading at first and second distal ends of the tensioning mechanism 102. For instance, an embodiment of a tensioning mechanism 102 may comprise 201a having standard clockwise threading and the 201b having counter-clockwise threading. This configuration of tensioning mechanism 102 is commonly referred to as a turnbuckle. In certain embodiments a tensioning mechanism 102 comprises a length of 10.2 cm (4.0 in) and diameter of 15.875 mm (0.625 in) In such an embodiment the tension application components 101a and 101b, as shown in FIG. 3, have a cylindrical profile with a length of screw threading, 301a and 301b, at a proximal end 302 to engage with the threaded female features, 201a and 201b, of the tensioning mechanism 102. Furthermore, the distal section 303 of the tension application component has a bend which provides a post-like form 304 to allow the application of force upon an existing structure or aperture prepared in a structure for the placement of the tension application components 101a and/or 101b. It will be appreciated that the bend in the tension application components 101a and/or 101b may comprise a plurality of angular bends typically totaling at least 90-degrees. In certain embodiments the female threaded features as illustrated by FIG. 2, the threaded female features 201a and 201b have screw threading having a lead of 1.5875 mm (0.0625 in) and a diameter of 9.525 mm (0.375 in). It will be appreciated to those skilled in the art that lead, surrounding male threaded features, indicates the axial travel for a single revolution of the screw thread. In such an embodiment, the screw threading 301a and 301b, seen in FIG. 3, also have screw threading having a lead of 1.5875 mm (0.0625 in). Such embodiments may be designated with ANSI thread designation as ⅜-16 per ANSI/ASME B1.1-1989 (R2001). Certain embodiments of a post-like form 303 as seen in FIG. 3, comprises a length of 44.45 mm (1.75 in) and diameter of 9.525 mm (0.375 in). It will be appreciated that other embodiments may have post-like forms of different lengths. It will be appreciated that a tension application component 303, shown to have a matching cross-section to the male threaded features 301a and 301b, are not limited to a round cross-section or dimensions matching that of the male threaded features 301a and 301b. It will be further appreciated that the threading associated with the male threaded features 301a and 301b, seen in FIG. 3, and the female threaded features 201a and 201b may comprise threading larger or smaller than embodiments described herein. Certain embodiments of a tension application feature 101a and 101b may comprise a length of 12.7 cm (5.0 in).

It will be appreciated by those skilled in the art that a post-tensioning device may be made of a steel alloy designated as a hot rolled and proof stressed alloy steel conforming to ASTM A722 CAN/CSA (G279-M1982). It will be further appreciated that certain embodiments may be made of a steel allow such as AISI 1144, sometimes referred to by an associated trade name of Stressproof®. AISI 1144 steel is appreciated to those skilled in the art as a is a carbon-manganese grade steel which is severely cold worked to produce high tensile properties.

Certain embodiments such as those shown in FIGS. 1A-3 are directed to the repair of a concrete structure where a fissure or crack has occurred due to mechanical failure. The surface is prepared by placing apertures in the concrete on either side of the fissure or crack. The apertures are positioned at a distance that generally corresponds to the the length of the apparatus 100 with attached tension application components 101a and 101b prior to actuation of the tensioning mechanism 102 which shortens the mechanism. The distal end 303 of tension application components 101a and 101b, such as the those shown in FIG. 3, into the corresponding apertures of the prepared surface. Tension can then be applied by actuating the tensioning mechanism 102 to creating post-tensioning in the area surrounding the crack or fissure.

In certain embodiments of the apparatus as shown in FIGS. 4A-5C, a tension application component 401 applies tensile load across a desired structure. The tension application component 401 comprises an attachment feature 402 at a proximal end 403 for engaging with a tensioning mechanism and an aperture 404. The distal end 405 has a tension application feature 404, such as an aperture or hook-form, configured to engage with features installed in the structure. Such features include, but are not limited to, a post or rebar, affixed to the structure.

Certain embodiments of the invention, as shown in FIGS. 6A, 6B, 7A, 7B and 7C, comprise a tension application component 601 that engages with a tensioning mechanism 102. A proximal end 603 of the tension application component 601 has an attachment feature 602 configured to engage with the tensioning mechanism 102. The distal end 605 of the tension application component 601 is configured to engage the apertures of a prepared surface or the edges of an existing structure by having a plurality of post-like features 604. Having a plurality of post-like features 604 distributes the load of the tensioning mechanism 102 across a larger area. The distribution of forces allows the installation of a post-tensioning apparatus 601 in conjunction with structures that cannot offer structural stability for an apparatus with a more concentrated loading. Certain embodiments of a tension application component 601 as seen in FIG. 6A-C has a two parallel post-like features 604 interconnected such that the post like features are separated by a distance of 8.89 cm (3.5 in). In the scenario which a user may want to use more than one post-tensioning apparatus 601, the plurality of post-like features 604 allows the use of fewer post-tensioning apparatuses 601 over a given length of a fissure or crack to achieve stronger structural ability. Certain embodiments of an aperture 404 as seen in FIG. 4, comprise a length of 19.05 mm (0.75 in) and width of 12.7 mm (0.5 in). Certain embodiments of a tension application feature 405 as seen in FIGS. 4A and 4B has a length of 59.18 mm (2.33 in), width of 31.75 mm (1.25 in) and thickness of 9.525 mm (0.375 in).

Certain embodiments have a tension application component. Such as those shown in FIGS. 8A, 8B, 8C, 9A, 9B and 9C, a tension application component 801 comprises a plate-form 802, the plate-form 802 having at least one aperture 803. The plate-form 802 affixes to a structure, typically using at least one aperture 803 in the plate-form 802. The plate-form 802 may be affixed to the structure through an aperture 803. Fixation strategies include the use of threaded features, masonry anchors and other methods known to those skilled in the art. This allows the application of tensile load to the structure at the desired location. The plate-form 802 further comprises and engagement features, such as a threaded male component 804 extending outward from the surface of the plate-form, typically axially parallel to the bore of an aperture in the plate-form. This engagement feature is configured to engage with a tensioning mechanism 102. In such an embodiment, a tension application component 801 can be attached to a first surface at an angle to, typically orthogonal, and attached to a second surface. This allows post tensioning across a crack or fissure that has occurred proximal to a corner where two surfaces of the structure or adjacent structures meet at an angle. It will be appreciated to those skilled in the art that a plurality of apertures 803 may be used to affix the plate-form 802 to the structure. The use of a plurality of apertures 803 in conjunction distributes the load born by the fixation features. Certain embodiments of a plate-form 802 has a length of 12.7 cm (5.0 in), width of 31.75 mm (1.25 in) and thickness of 6.35 mm (0.25 in). In such embodiments, a plate-form 802 further comprises a male threaded component 804 disposed centrally to the width of the plate-form and 8.255 mm (0.325 in) from a longitudinal end of the plate-form, extending orthogonally from the plate-form.

Certain embodiments of the invention, as shown in FIGS. 10A and 10B, comprise a tension application component 1001 having at least two parallel post structures 1002. The two parallel post structures 1002 are disposed at an angle from a connecting body 1003. The tension application component 1001 has an aperture 1004 located medial to the post structures 1002. The aperture 1004 is also typically axially parallel to the post structures. The tension application component 1001 distributes the load applied to the structure and provides a post-tensioning effect to a larger area. In certain embodiments, a second tension application component, such as 101a in FIG. 3, has a post feature attached to a tensioning mechanism, where the post-feature 304 is disposed through the medially located aperture 1004. Certain embodiments of a tension application component as seen in FIG. 10B comprises a medially located aperture 1004 in a medially mounted tab 1005 affixed to the tension application component. In such embodiments, a medially located aperture 1004 comprises a width of 12 mm (0.473 in) and length of 12.7 mm (0.5 in), the medially mounted tab 1005 having a length and width of 25.4 mm (1.00 in), and the tension application component having an overall length of 30.5 cm (12.0 in).

Certain embodiments have a tension application component. In certain embodiments of, as shown in FIG. 11, the tension application component comprises a plate-form 1102. The plate-form 1102 affixes to a structure to apply tensile load to the structure at the desired location. The plate-form 1102 can be affixed by masonry anchors or threaded features through apertures 1103 in the plate-form 1102, welding or other methods known to those skilled in the art. The plate-form 1102 further comprises a fixation point 1104 configured to engage through a secondary tension application component, such as having a loop, hook, post-like feature or aperture. In the case of the plate-form 1102 being fixated through the use of a plurality of fasteners or anchors, this distributes any tensile loading applied to the fixation point such as when applying post-tensioning across a fissure or crack. The distributed load can also provide tension between independent structures where other types of tension application components cannot. For example, post-like forms create a higher localized concentration of stress and do not offer the necessary structural stability to provide tension between independent structures.

In certain embodiments of the invention such as that shown in FIG. 2, the apparatus comprises a tensioning mechanism, the tensioning mechanism 102 having consistent cross-section. The tensioning mechanism 102 can have female threaded features, 201a and 201b, at its distal ends. The threaded receptacles, 201a and 201b, having opposing threading direction. Thus, when engaged with rotationally constrained male threaded features, the opposite threading direction allows both male threaded features to be drawn toward the center of the tensioning mechanism 102 when rotated in a first direction and forces the male threaded features away from center when rotated a second direction, opposite the first direction. Alternatively, it will be appreciated that the tensioning mechanism may have male threaded features and the tension application components have female threaded features.

In certain embodiments, the tensioning mechanism has a torque application feature. The torque application feature actuates the tensioning mechanism by to applying rotational forces to tension application components. The torque application feature may have different individual forms or a combination of forms as known to those skilled in the art. The profile of the tensioning mechanism may have forms including but not limited to elliptical, circular, hexagonal, octagonal or square.

In certain embodiments the tensioning mechanism 102, such as that shown in FIG. 2, has at least one at least one torque application aperture 202. The torque application aperture 202, passes through the tensioning mechanism perpendicular to the central axis of the mechanism typically intersecting the central axis of the tensioning mechanism 102. The torque application aperture 202 allows for torque application through the use of a rod or other shaft-like object. After torque application, it may be desired to dispose a rod in the torque application aperture 202 to prevent counter-rotation by engaging the rod with the structure, such as concrete, to which an apparatus comprising a tensioning mechanism 102 is applied. It will be appreciated to those skilled in the art, that apertures 202 are typically be in a medial section of the tensioning mechanism 102. Furthermore, it may be desired to have a plurality of apertures. The additional apertures 202 can be radially displaced from other apertures such as on 45-degree or 90-degree increments that allow for easier adjustment of the tensioning mechanism 102 in tighter locations. The apertures 202 may be coplanar to the axis of the central axis. In certain embodiments, the apertures 202 may be located on offset yet parallel planes perpendicular to the axis of the central axis of the tensioning mechanism 102.

In certain embodiments, the external profile of a tensioning device comprises a form with parallel exterior surfaces, such as a square, hexagonal or octagonal form, wherein the external profile may be used for the application of torque with a tool such as a wrench or other standard torque tool.

Embodiments of the invention disclosed herein may be used in a system comprising at least one tensioning mechanism and at least two tension application components wherein the tensioning components are interchangeably with a tensioning mechanism to allow system customization for each application. In such an embodiment of a system the tension application components may have a threading to match the tensioning mechanism with right-hand or left-hand threads alternatively. It will be appreciated that a system comprising at least one tensioning mechanism and at least two tension application components may comprise a first tension application component of a first type and a second tension application component of a second type.

In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present teachings. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.

Claims

1. An apparatus for applying tension to cracked concrete surfaces comprising:

a tensioning mechanism comprising a constant cross-sectional profile, a first female threaded feature at a first distal end of said tensioning mechanism, a second female threaded feature at a second distal end of said tensioning mechanism, and a torque application feature located medially between said first and second female threaded features;

a first tension application component, with a proximal end aligned with and proximate to said first distal end of said tensioning mechanism, said first tension application component having a male threaded feature at said proximal end of said first tension application component, said first tension application component having at least one structure engaging feature located at a distal end of said first tension application component;

a second tension application component, with a proximal end aligned with and proximate to said second distal end of said tensioning mechanism, said second tension application component having a male threaded feature at said proximal end of said second tension application component; said second tension application component having at least one structure engaging feature located at a distal end of said second tension application component;

said male threaded features of said first tension application component and said second tension application component configured to engage with said female threaded features of said tensioning mechanism wherein the rotation of the tensioning mechanism in a first direction causes said first tension application component and said second tension application components to retract toward a center of said tensioning mechanism and rotation in a second direction causes the first and second components to protract from the center of the tensioning mechanism;

wherein actuation of said tensioning mechanism by rotation allows post-tensioning of a structure when said first tension application component and said second tension application component are engaged with said structure.

2. The apparatus of claim 1, wherein said structure engaging feature of said first tension application component and said second tension application component are selected from the group consisting of: post-form, plate-form, loop, hook-form fixation point or aperture.

3. The apparatus of claim 1, wherein the threading of said male threaded features and said female threaded features are of ANSI thread designation 3/8-16.

4. The apparatus of claim 1 wherein said apparatus comprises a material composition comprising a steel alloy designated as a hot rolled and proof stressed alloy steel conforming to ASTM A722 CAN/CSA (G279-M1982).

5. The apparatus of claim 1 wherein said apparatus comprises a material composition comprising a steel allow designated as AISI 1144 compliant.

6. The apparatus of claim 1 wherein said torque application feature comprises a torque application aperture.