WO2020222131A1

WO2020222131A1 - A mechanical nut coupler for single rebar

Info

Publication number: WO2020222131A1
Application number: PCT/IB2020/054022
Authority: WO
Inventors: Sangeeta Gadve; Naseeruddin Haris
Original assignee: Sangeeta Gadve; Naseeruddin Haris
Priority date: 2019-04-30
Filing date: 2020-04-29
Publication date: 2020-11-05
Also published as: IN201921017240A

Abstract

The present disclosure describes a mechanical nut coupler 100 for single rebar 108. The coupler 100 comprises a hexagonal nut 101, two flat washer plates (103,104) and an additional plate 106. The nut 101 comprises a threaded bore 102 throughout its length. Each washer plate (103,104) comprises a hole that passes throughout its thickness. The washer plates (103,104) are friction welded 105 at top surface and bottom surface of the nut 101 respectively. The hole of each washer plate (103,104) is coaxially aligned with the threaded bore 102 of the nut 101. The additional plate 106 is friction welded 105 to flat washer plate 103, placed at the bottom surface of the nut facilitating orthogonal alignment to flat end of the single rebar 108. The threaded bore 102 is filled with polymer 107; following entry of the single rebar 108 into the coupler 100, protecting the rebar 108 from corrosion.

Description

A MECHANICAL NUT COUPLER FOR SINGLE REBAR

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY

The present application claims priority from Indian Patent Application number 201921017240 filed on 30^th April, 2019.

TECHNICAL FIELD

The present invention in general relates to a field of civil engineering. More particularly, the invention relates to a mechanical nut coupler for anchoring single rebar.

BACKGROUND

The reinforcement (rebar) in structural members of cast-in-situ, precast or retrofitted concrete structures are provided either to carry design loads at end support locations or to transfer it coaxially through rebar requires necessary anchorage arrangements. These rebars are provided either in the form of development length of rebar, T-headed bar or, threaded coupler, and the like. The larger development length of the rebar leads to congestion of reinforcement at end support. The T- headed bars and threaded couplers require threading of rebars for their application.

On the other hand, other couplers have a sophisticated on-site application which can be complex and have very specific set of requirement for installation. The corrosion protection of rebar inside such existing couplers, cannot be assured. The corrosion of rebar is evident with mass loss and bond loss. The mass loss leads to reduction in design load carrying capacity and bond loss leads to reduction in anchorage of rebar. There is a need of a rebar coupler that can avoid above mentioned problems/situations along with an ease of manufacture and quick, fast and easy installation at desired locations/sites. SUMMARY

Before the present apparatuses, methods and systems along with components related thereto are described, it is to be understood that this disclosure is not limited to the particular methods, apparatuses, systems and their arrangement as described, as there can be multiple possible embodiments which are not expressly illustrated in the present disclosure but may still be practicable within the scope of the invention. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present application. This summary is not intended to identify essential features of the subject matter nor it is intended for use in detecting or limiting the scope of the subject matter.

In one embodiment, a mechanical nut coupler for a single rebar is described. The coupler may comprise a hexagonal nut, at least two flat washer plates and an additional plate. The nut may comprise a threaded bore throughout the length of the nut. Each washer plate may comprise a hole located at centre of the plate. The hole of the washer plate may pass throughout the thickness of the washer plate. The washer plate may be friction welded at top surface and bottom surface of the nut respectively. The hole of each washer plate may be coaxially aligned with the threaded bore of the nut. The additional plate may be further welded to at least one flat washer plate via friction welding technique. The additional plate may be welded to at least one flat washer plate placed at the bottom surface of the nut. The single rebar may enter into the coupler from at least one of the washer plate placed at the top surface of the nut. The additional plate may further facilitate resting of flat end of the single rebar on to the additional plate and further provide an orthogonal alignment of the single rebar with respect to the additional plate.

In another embodiment, a method of manufacturing of a mechanical nut coupler and anchoring the single rebar is described. The method may comprise a step for aligning of hole of each washer plate with threaded bore of the nut coaxially. Each washer plate may comprise a hole located at the centre of the plate that passes throughout the thickness of the washer plate. The method may comprise a step for welding of at least two flat washer plates to a hexagonal nut via a friction welding technique. The washer plate may be welded at top surface and bottom surface of the nut respectively. The method may further comprise a step for welding an additional plate is welded to at least one flat washer plate, via friction welding technique, placed at the bottom surface of the hexagonal nut. The single rebar may enter into the coupler via at least one flat washer plate placed at the top surface of the hexagonal nut. The additional plate may facilitate resting of flat end of the single rebar and may further provide an orthogonal alignment of the single rebar with respect to the additional plate. The method may comprise a step for filling of polymer into the threaded bore of the hexagonal nut. The single rebar may be entered into the polymer filled threaded bore of the nut, further forming a solid polymer core when the polymer 107 hardens. The solid polymer core may provide anchorage to the single rebar such that embedded surface of the single rebar, present within the coupler, is anchored by continuous contact with the solid polymer core, thereby protecting the single rebar from corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanying Figures. In the Figures, the left-most digit(s) of a reference number identifies the Figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

Figure 1 illustrates a mechanical nut coupler for a single rebar 108, in accordance with an embodiment of the present disclosure.

Figure 2 illustrates a method 200 of manufacturing a mechanical nut coupler 100 and anchoring the single rebar 108, in accordance with an embodiment of the present disclosure.

DETAIFED DESCRIPTION

Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary methods are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.

Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated, but is to be accorded the widest scope consistent with the principles and features described herein.

The present disclosure describes a mechanical nut coupler used for anchoring single rebar. The nut coupler facilitates quick and easy alignment of rebar into the nut coupler. The nut coupler can be used for cast-in-situ, precast or retrofitted cement concrete structures or for existing rebar under repairs and/or retrofit of concrete buildings or structures.

Figure 1 illustrates a mechanical nut coupler 100 for a single rebar 108, in accordance with an embodiment of the present disclosure. The coupler 100 may comprise a hexagonal nut 101, at least two flat washer plates (103,104) and an additional plate 106. The nut 101 may comprise a threaded bore 102 throughout the length of the nut 101. Each washer plate (103,104) may comprise a hole located at centre of the plate. The hole of the washer plate (103,104) may pass throughout the thickness of the washer plate. The washer plate (103,104) may be a flat washer plate and may be of steel material. The hole of flat steel washer plate (103,104) may be at least the maximum diameter of the rebar. (Hereinafter the flat steel washer plate (103,104) may be referred as washer plate (103,104) and can be used interchangeably). The hole of flat steel washer plate (103,104) may be in a predefined range of 1 mm to 3mm larger than the maximum diameter of the rebar 108. The ratio of diameter of the threaded bore 102 of the hexagonal nut 101 may be at least 3mm larger than maximum diameter of the rebar 108. The washer plate (103,104) may be further welded, via friction welding technique, at top surface and bottom surface of the nut 101 respectively. The hole of each washer plate (103,104) may be coaxially aligned with the threaded bore 102 of the nut 101.

An additional plate 106 may be further welded 105 to at least one flat washer plate via friction welding technique. The additional plate 106 may be of steel material. The additional plate 106 may be welded 105 to the at least one flat washer plate 103 placed at the bottom surface of the nut 101. The additional plate 106 may act as a base for installation of the nut coupler 100 at desired location/site. The additional plate 106 may be placed such that the single rebar 108 enters into the coupler 100 from at least one of the washer plate 104 placed at the top surface of the nut. The additional plate 106 may further facilitate resting of flat end of the single rebar 108 on to the additional plate 106 and further provide an orthogonal alignment of the single rebar 108 with respect to the additional plate 106, thereby forming a nut coupler 100. The ratio of length/height of the nut coupler 100 to the diameter of single rebar 108 to be inserted in the nut coupler 100 may be in a predefined range of 6 to 10.

The threaded bore 102 of the nut 101 is further filled/grouted with a polymer 107 in order to form a solid polymer core that enables smooth entry of the single rebar 108 into the coupler 100 for anchorage. The polymer filled/grouted in the threaded bore 102 of the nut 101 may be either epoxy, epoxy resin or the like. Sufficient quantity of epoxy may be utilized to fill the threaded bore 102 entirely and cover the embedded surface the single rebar 108 that is to be entered. The single rebar 108 may be further inserted through the washer plate 104 placed at the top surface of the nut until the rebar 108 reaches the additional plate 108. A solid epoxy core may be formed when the epoxy fully becomes hard; the embedded rebar 108 may couple to the solid epoxy core. The nut coupler 100 may further create a high strength mechanical anchorage to embedded rebar 108 and may enable concrete structures to resist design loads along with an assured corrosion protection. It can be said that the embedded surface of the rebar 108, present within the coupler 100, may be anchored by continuous contact with the solid epoxy core, thereby protecting the rebar 108 from corrosion.

Figure 2 illustrates a method 200 of manufacturing a mechanical nut coupler 100 and anchoring the single rebar 108, in accordance with an embodiment of the present disclosure. As illustrated in figure 2, the method 200 of manufacturing a mechanical nut coupler 100 and anchoring the single rebar 108 is divided into various steps as described below:

Step 201 : Aligning of hole of each washer plate (103, 104) with threaded bore 102 of a hexagonal nut 101 coaxially.

Step 202: Welding 105 of at least two flat washer plates (103,104) to the hexagonal nut 101 via a friction welding technique

Step 203: Welding 105 of an additional plate 106 is welded to at least one flat washer plate 103, via friction welding technique, placed at the bottom surface of the hexagonal nut 101.

Step 204: Filling/Grouting of polymer 107 into the threaded bore 102 of the hexagonal nut 101.

Step 205: Entering the rebar 108 into the polymer filled threaded bore 102 of the nut 101 via the hole of washer plate 104 placed at top surface of the nut 101, further facilitating resting of flat end of the single rebar 108 on to the additional plate 106, providing an orthogonal alignment of the single rebar 108 with respect to the additional plate 106 and/or the nut coupler 100.

Step 206: Forming a solid polymer core when the polymer 107 hardens.

In one embodiment, the washer plate (103,104) may comprise a hole located at the centre of the plate that passes throughout the thickness of the washer plate. The washer plate (103,104) may be welded 105 at top surface and bottom surface of the nut 101 respectively. The washer plate (103,104) may be flat and made up of steel material.

In another embodiment, the polymer 107 may be either epoxy, epoxy resin and the like. A solid epoxy core may be formed when the epoxy hardens. The single rebar may be entered into the polymer filled threaded bore 102 of the nut 101 for anchorage such that embedded surface of the single rebar 108, present within the coupler 100, is anchored by continuous contact with the solid epoxy core, thereby protecting the single rebar 108 from corrosion. In accordance with embodiments of the present disclosure, the mechanical nut coupler for single rebar and method of manufacture thereof, described above may have following advantages including but not limited to:

• Simple to manufacture, hence can also be casted in parts to lower the cost of welding.

• Easy to install/use at desired location/site.

• Can be directly assembled in field/place of application.

• Quick and easy alignment of rebar.

• Provide corrosion protection to the embedded length of rebar throughout its design life of the rebar, etc.

• Provides high and efficient torsion transfer when the rebar is subjected to torsional forces.

• More number of nut couplers can be accommodated (compared to circular coupler) in per unit area of concrete section.

The embodiments, examples and alternatives of the preceding paragraphs or the description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

Claims

We Claim:

1. A mechanical nut coupler 100 for single rebar 108, the coupler comprising:

a hexagonal nut 101, wherein the nut 101 comprises a threaded bore 102 throughout the length of the nut 101 ;

at least two flat washer plates (103,104), wherein each washer plate comprises a hole located at the centre of the plate that passes throughout the thickness of the washer plate, wherein each washer plate is friction welded 105 at top surface and bottom surface of the nut 101 respectively, such that the hole of each washer plate is coaxially aligned with the threaded bore 102 of the nut 101; and

an additional plate 106, wherein the additional plate 106 is friction welded 105 to at least one flat washer plates 103 placed at the bottom surface of the nut 101 such that the entry of single rebar 108 into the coupler 100 is from at least one of the washer plate 104 placed at the top surface of the nut 101, wherein the additional plate 106 facilitates resting of flat end of the single rebar 108 on to the additional plate 106, providing orthogonal alignment of the single rebar 108 with respect to the additional plate 106.

2. The coupler 100 as claimed in claim 1, wherein the threaded bore 102 of the nut 101 is filled/grouted with a polymer 107 to form a solid polymer core, further enabling smooth entry of the single rebar 108 into the coupler 100 for anchorage, wherein embedded surface of the single rebar, present within the coupler 100, is anchored by continuous contact with the solid polymer core, thereby protecting the single rebar 108 from corrosion.

3. The coupler 100 as claimed in claim 2, wherein the polymer 107 is either epoxy or epoxy resin.

4. The coupler 100 as claimed in claim 1, wherein diameter of the threaded bore 102 of the nut 101 is at least 3mm larger than maximum diameter of the single rebar 108.

5. The coupler 100 as claimed in claim 1, the hole of each washer plate (103, 104) is at least the maximum diameter of the single rebar 108.

6. The coupler 100 as claimed in claim 5, wherein the hole of each washer plate

(103,104) is 1 mm to 3mm larger than the maximum diameter of the single rebar 108.

7. The coupler 100 as claimed in claim 1, wherein material of the flat washer plate

(103.104) is steel.

8. The coupler 100 as claimed in claim 1, wherein the ratio of length of the coupler 100 to the diameter of single rebar 108 is in range of 6 to 10.

9. A method 200 of manufacturing a mechanical nut coupler 100 and anchoring a single rebar 108, the method comprising:

aligning, hole of each washer plate (103,104) with threaded bore 102 of the nut 101 coaxially, wherein each washer plate (103, 104) comprises a hole located at the centre of the plate that passes throughout the thickness of the flat washer plate

(103.104);

welding, of at least two flat washer plates (103,104) to a hexagonal nut 101, wherein at least one washer plate (103,104) is friction welded 105 at top surface and bottom surface of the nut 101 respectively;

welding, of an additional plate 106 to at least one flat washer plate 103, via friction welding technique 105, placed at the bottom surface of the hexagonal nut 101, wherein the single rebar 108 is entered into the coupler 100 via at least one flat washer plate 104 placed at the top surface of the hexagonal nut 101, wherein the additional plate 106 facilitates resting of flat end of the single rebar 108 and providing an orthogonal alignment of the single rebar 108 with respect to the additional plate 106; filling, of polymer 107 into the threaded bore 102 of the hexagonal nut 101; entering, the single rebar 108 into the polymer filled threaded bore 102 of the nut 101 for the rebar anchorage via at least one flat washer plate 104 placed at the top surface of the hexagonal nut 101 such that embedded surface of the single rebar 108, present within the coupler 100; and

forming, a solid polymer core when the polymer 107 hardens, wherein embedded surface of the rebar 108 is anchored by continuous contact with the solid polymer core, thereby protecting the single rebar 108 from corrosion.