AU2006100394B4

AU2006100394B4 - Plate dowel system for concrete slabs

Info

Publication number: AU2006100394B4
Application number: AU2006100394A
Authority: AU
Inventors: David Tyler
Original assignee: Connolly Key Joint Pty Ltd
Current assignee: Connolly Key Joint Pty Ltd
Priority date: 2006-05-11
Filing date: 2006-05-11
Publication date: 2006-06-15
Anticipated expiration: 2014-05-11
Also published as: AU2006100394A4

Description

P/00/012 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: "PLATE DOWEL SYSTEM FOR CONCRETE SLABS" The following statement is a full description of this invention, including the best method of performing it known to us: TITLE: PLATE DOWEL SYSTEM FOR CONCRETE SLABS BACKGROUND OF THE INVENTION 1. Field of the Invention THIS INVENTION relates to a plate dowel system for concrete slabs.

The invention is particularly suitable for, but not limited to, an apparatus for use in transferring a load across a joint between first and second cast-in-place concrete slabs incorporating a plate dowel system with a dowel sheath embedded within the first slab and a plate dowel embedded in, and extending from, the second slab.

2. Prior Art Over the years, many dowel systems have been proposed to transfer loads between, and accurately locate, first and second cast-in-place concrete slabs. Typically, the dowels have been circular, square or plate-like in cross-section and have been slidably received within a complementary dowel sheath embedded in the other of the slabs at spaced locations along the joint between the adjacent slabs.

SUMMARY OF THE PRESENT INVENTION It is an object of the present invention to provide a plate dowel system where the plate dowel and the plate sheath are adapted to transfer across the joint between the first and second slabs any vertical load applied to either the first or second slab while allowing limited relative movement between the first and second slabs in a horizontal direction parallel to the joint.

It is a preferred object to provide a plate dowel system where rectangular dowel plates have a large, constant, bearing width at the joint _plate despite the distance across the joint between the first and second slabs.

It is a further preferred object to provide such a plate dowel 0 system where the dowel sheath incorporates internal guides or fins operable Ito guide the dowel plates to a central position in the dowel sheaths as the dowel plates are inserted into the dowel sheaths.

It is a further preferred object of the present invention to provide compressible spacers in the dowel sheaths which are initially located adjacent the openings to the dowel sheaths to prevent the dowel sheaths from being compressed while the slab is being cast but which can be pushed into, and compressed within, the dowel sheaths by the dowel plates as the dowel plates are inserted into the dowel sheaths.

Other preferred objects of the present invention will become apparent from the following description.

In a broad aspect, the present invention resides in an apparatus for use in transferring a load across a joint between first and second cast-in-place slabs, the joint having a joint surface substantially perpendicular to a substantially planar upper surface of the first slab, the apparatus including: a dowel sheath adapted to be embedded within the first slab, the dowel sheath being substantially rectangular in plan view, with substantially planar top and bottom faces of the dowel sheath substantially parallel to the upper surface of the first slab and an opening to the interior of the dowel sheath substantially aligned with the joint face; and a plate dowel having a substantially rectangular end portion in plan view and a remaining portion, the end portion having substantially planar upper and lower surfaces, the end portion being adapted to be 0 inserted into the dowel sheath, the upper and lower surfaces of the end Iportion being adapted to co-operatively engage the substantially planar top Sand bottom surfaces of the dowel sheath, the remaining portion of the dowel plate being adapted to be embedded in the second slab; the dowel plate and the dowel sheath being adapted to transfer between the first and second slabs any load applied to either the first or second slab in a vertical direction perpendicular to the upper surface of the first slab; and the dowel plate and the dowel sheath being adapted to allow limited relative movement of the first and second slabs in a horizontal direction parallel to the joint surface under any load applied to either the first or second slabs in a horizontal direction parallel to the joint surface.

Preferably, the horizontal width between side walls of the dowel sheath is slightly larger than the horizontal width between side edges of the end portion of the dowel plate; and the vertical height between the top and bottom surfaces of the dowel sheath is just greater than the vertical height between the upper and lower surfaces of the dowel plate.

Preferably, the horizontal length of the interior of the dowel sheath is greater than the horizontal length of the end portion of the dowel plate, the difference in lengths being operable to provide a cavity adjacent a rear wall of the dowel sheath to receive non-compressible spacer means moved from a position adjacent the opening of the dowel sheath as the dowel plate is inserted into the dowel sheath.

Preferably, the horizontal width of the side walls of the dowel sheath exceeds the horizontal width between the side edges of the end portion of the dowel plate by 10-30mm, more preferably 10-20mm; and flexible fins or ribs on the top and bottom faces of the dowel sheath extend into the interior of the dowel sheath to provide guide means for the dowel plate as the dowel plate is inserted into the dowel sheath.

Preferably, the spacer means are substantially triangular in plan view with their bases initially aligned with the opening and are formed of compressible material, the spacers being operable to prevent the top and bottom faces of the dowel sheath being moved relatively towards each other as the first slab is cast but operable to be forced towards the rear wall of the dowel sheath as the dowel plate is inserted into the dowel sheath.

BRIEF DESCRIPTION OF THE DRAWINGS To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings, in which: FIG. 1 is a rear perspective view of the dowel sheath; FIG. 2 is a sectional top plan view of the dowel sheath taken on line A-A on FIG. 3; FIG. 3 is a front elevational view of the dowel sheath; FIG. 4 is a top sectional view, corresponding to FIG. 3, showing the dowel plate inserted into the dowel sheath; and FIG. 5 is a side sectional view corresponding to FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The dowel sheath 10 has a top wall 11 and bottom wall 12 interconnected by side walls 13, 14, from which extend flanges 15, 16 having holes 17, 18 to receive respective nails N to fix the dowel sheath 10 to the formwork for a first slab S1 to be cast-in-place. A rectangular cavity 18 in the dowel sheath 10 is defined by top and bottom surfaces 19, 20, the side walls 13, 14, a rear wall 21 and an opening 22, the opening 22 being surrounded by a peripheral flange 23.

Spacers 24 which are initially triangular in plan view are located at the opening 22 and engage the top and bottom faces 19, 20 of the dowel sheath 10 to prevent the dowel sheath 10 from collapsing while the first slab S1 is being cast. The spacers 24, formed of non-compressible material, eg., non-compressible plastics, are operable to be urged towards the rear wall when the dowel plate (to be hereinafter described) is inserted into the cavity 18 in the dowel sheath Resilient fins 25 on the top and bottom faces 19, 20 are spaced approximately 10-15mm from the adjacent side walls 13, 14 and are adapted to guide the dowel plate towards a central location within the dowel sheath The dowel plate 30 is formed of a rectangular piece of steel and is not fixed to the reinforcing steel (not shown) for the second slab S2 to be cast-in-place. As shown in FIGS. 3 and 4, the end portion 31 of the dowel plate 30, extending from the slab S2, is inserted into the cavity 18 of the dowel sheath 10 and the remaining portion 32 of the dowel plate 30 is embedded in the concrete when the second slab S2 is cast.

The vertical height between the upper and lower surfaces 33, 34 of the dowel plate 30, is just less than the vertical height between the top and bottom surfaces 19, 30, of the dowel sheath 10 so that any vertical loads applied to either of the slabs S1, S2 will be effectively transmitted across the joint to the other of the slabs S1, S2.

The horizontal width between the side edges 35, 36 of the dowel plate 30 is preferably approximately 20-30mm less than the horizontal width between the side walls 13, 14 of the dowel sheath to allow limited horizontal movement between the slabs S1, S2 when any horizontal load or shrinking is applied to the slabs S1, S2.

The fins 25 within the dowel sheath 10 guide the dowel plates towards central locations within the dowel sheaths 10 so that the degree of horizontal movement between the respective slabs S1, S2 is substantially equal in both horizontal directions.

The dowel sheath 10 is preferably injection-moulded of suitable plastics material, eg., PVC, polyethylene, polypropylene, ABS, and the holes 17, 18 in the flanges 15, 16 enable quick and accurate fixing of the dowel sheath 10 to the formwork for slab S1.

It will be apparent to the skilled addressee that the dowel plate system of the present invention provides a simple, economical, yet effective, apparatus for transferring loads across a joint between first and second castin-place slabs.

While the dowel plate 30 has been shown as being rectangular in plan view, the dowel plate 30 may also be square, with complementary changes to the dimensions of the dowel sheath The rectangular (or square) dowel plates 30 have a large bearing width at the joint between the first and second slabs S1, S2, and the bearing width remains constant regardless of the spacing across the joint between the adjacent faces of the slabs S1, S2.

To assist in the fixing of the peripheral flange 23 of the dowel sheath 10 to the formwork of the first slab S1, alignment notches or slots 29 may be provided at each end of the peripheral flange 23 (see FIGS. 1 and 2).

Various changes and modifications may be made to the embodiments described and illustrated without departing from the present invention.

Claims

1. Apparatus for use in transferring a load across a joint between first and second cast-in-place slabs, the joint having a joint surface substantially perpendicular to a substantially planar upper surface of the first slab, the apparatus including: a dowel sheath adapted to be embedded within the first slab, the dowel sheath being substantially rectangular in plan view, with substantially planar top and bottom faces of the dowel sheath substantially parallel to the upper surface of the first slab and an opening to the interior of the dowel sheath substantially aligned with the joint face; and a plate dowel having a substantially rectangular end portion in plan view and a remaining portion, the end portion having substantially planar upper and lower surfaces, the end portion being adapted to be inserted into the dowel sheath, the upper and lower surfaces of the end portion being adapted to co-operatively engage the substantially planar top and bottom surfaces of the dowel sheath, the remaining portion of the dowel plate being adapted to be embedded in the second slab; the dowel plate and the dowel sheath being adapted to transfer between the first and second slabs any load applied to either the first or second slab in a vertical direction perpendicular to the upper surface of the first slab; and the dowel plate and the dowel sheath being adapted to allow limited relative movement of the first and second slabs in a horizontal direction parallel to the joint surface under any load applied to either the first or second slabs in a horizontal direction parallel to the joint surface.

2. Apparatus as claimed in Claim 1 wherein: the horizontal width between side walls of the dowel sheath is slightly larger than the horizontal width between side edges of the end portion of the dowel plate; and the vertical height between the top and bottom surfaces of the dowel sheath is just greater than the vertical height between the upper and lower surfaces of the dowel plate.

3. Apparatus as claimed in Claim 2 wherein: the horizontal length of the interior of the dowel sheath is greater than the horizontal length of the end portion of the dowel plate, the difference in lengths being operable to provide a cavity adjacent a rear wall of the dowel sheath to receive non-compressible spacer means moved from a position adjacent the opening of the dowel sheath as the dowel plate is inserted into the dowel sheath.

4. Apparatus as claimed in Claim 2 or Claim 3 wherein: the horizontal width of the side walls of the dowel sheath exceeds the horizontal width between the side edges of the end portion of the dowel plate by 10-20mm; and flexible fins or ribs on the top and bottom faces of the dowel sheath extend into the interior of the dowel sheath to provide guide means for the dowel plate as the dowel plate is inserted into the dowel sheath. Apparatus as claimed in Claim 3 or Claim 4, wherein: the spacer means are substantially triangular in plan view with their bases initially aligned with the opening and are formed of non- compressible material, the spacers being operable to prevent the top and _bottom faces of the dowel sheath being moved relatively towards each other as the first slab is cast but operable to be forced towards the rear wall of the dowel sheath as the dowel plate is inserted into the dowel sheath.