GB2487243A

GB2487243A - Joist reinforced by a plate aligned with a web aperture

Info

Publication number: GB2487243A
Application number: GB201100732A
Authority: GB
Inventors: Scott Mcandrew
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2011-01-17
Filing date: 2011-01-17
Publication date: 2012-07-18
Anticipated expiration: 2031-01-17
Also published as: GB201100732D0; GB2487243B

Abstract

The invention relates to a reinforcement plate for attachment to an I-joist weakened by the removal of a portion of its web volume; the reinforcement plate comprising a sheet-like material for placement against a generally planar surface of an I-joist and having an opening therein configured to be aligned with the weakened portion of the I-joist, the opening being defined by an edge of the sheet-like material wherein the edge of the sheet-like material comprises a continuous flange depending therefrom and upstanding from the plane of the sheet-like material. Further flanges may be provided along edges of the sheet material, these further flanges may extend in the opposite direction to the flange surrounding the opening. The invention further relates to an I-joist assembly comprising an I-joist weakened by removal of a portion of its web and a reinforcement plate attached thereto, the plate may be attached to edges of the joist flanges so as to be spaced from the web of the joist.

Description

Reinforcement plate The present invention relates to the reinforcement of structural members used in the building and construction industry. In particular, the invention provides a reinforcement plate for strengthening an I-joist locally weakened by the removal of a portion of its volume. More particularly, the invention provides a reinforcement plate for strengthening an I-joist locally weakened by the removal of a portion of its web volume.

It is common practice in the building and construction industry to provide structural I-joists with portions of material removed to form passages, recesses or cut-out portions, thus facilitating the convenient routing of utilities such as piping, wiring and the like. Such an arrangement allows utilities to be concealed within, for example, the floor substructure thus saving space and providing a more aesthetically appealing finish.

An I-joist is typically formed by two flanges spaced apart from one another and connected to one another by way of a web between the two flanges.

The flanges are typically formed of a solid wood or a laminated veneer lumber material and the web of a plywood, a laminated veneer lumber, oriented strand board or the like. The web in attached between the flanges thereby forming a joist of "I"-shaped cross section.

An inherent consequence of removing material from the I-joist is that the overall load bearing capacity of the joist is reduced. To obviate the need to employ larger and thus more expensive joists to compensate for any predicted reductions in load bearing capacity, it is known in the industry to apply reinforcing brackets or plates to the joist in localised regions where material has been removed.

Unlike dimensional lumber joists, fixings upon an I-joist are limited to being made at the flanges, whereas the cut-out portion for access, ducting or the like may be located in the web portion. Removing a portion of the volume of the web of an I-joist significantly reduces the load bearing capacity of the joist.

Currently available solutions to the reduction in strength seen when a portion of the volume of the web of an I-joist is removed include limiting the location of the removed volume to certain areas of a structure and also limiting the dimensions of the removed volume portion. Failure to correctly locate the removed volume or increasing the size of the removed volume portion results in failure of the I-joist.

It is therefore an object of the present invention to obviate or mitigate one

or more of the disadvantages of the prior art.

According to a first aspect, the present invention provides a reinforcement plate for attachment to an I-joist weakened by the removal of a portion of its web volume; the reinforcement plate comprising a sheet-like material for placement against a generally planar surface of an I-joist and having an opening therein configured to be aligned with the weakened portion of the I-joist, the opening being defined by an edge of the sheet-like material characterised in that the edge comprises a continuous flange depending therefrom and upstanding from the plane of the sheet-like material.

In preferred embodiments, the opening in the sheet-like material is centrally aligned. More particularly, the opening is centrally positioned on the sheet-like material and is defined by a single, continuous edge thereabout. It will be understood that the opening forms an enclosed hole in the sheet-like material bounded on all sides by the sheet-like material.

Preferably the opening is rectangular, circular or obloid in shape. It is much preferred that the opening is obloid. When referred to herein the term "obloid" shall be taken to mean generally rectangular in shape with curved corners joining the upper, lower and side edges of the rectangle.

In embodiments wherein the opening is obloid, the continuous flange has upper and lower portions and two side portions. The upper, lower and side portions are continuously connected by curved corner sections of the flange. By way of the continuous curved corner sections of the flange, failure of the plate at the corners of the opening upon exposure to torsional forces is significantly reduced when compared to a flat plate having an opening therein.

Preferably the opening is dimensioned such that the continuous flange about the opening is locatable proximate the top and the bottom flanges of an I-joist. More specifically, the upper and/or lower portions of the flange of the reinforcement plate may be locatable proximate the top and/or bottom flange(s) of the I-joist respectively.

In certain embodiments, the flange of the reinforcement plate forms a frictional fit against the lower surface of the top flange of the I-joist.

Alternatively or, in addition, the flange of the reinforcement plate forms a frictional fit against the upper surface of the bottom flange of the I-joist. In such embodiments, the reinforcement plate is firmly locatable against the flanges of the I-joist by a frictional fit.

The continuous flange is provided in the reinforcement plate as a burst through in the sheet-like material. The burst through is formed by punching the opening through the sheet-like material.

The reinforcement plate may comprise apertures through which fastening means are locatable. The fastening means may include but are not limited to nails, screws, staples or the like.

The reinforcement plate may comprise one or more punch nail holes therein.

The reinforcement plate may comprise one or more truss nails. More specifically, the sheet-like material may have one or more truss nails formed therein such that the reinforcement plate may be attached to an I-joist with or without the need for additional fasteners.

It is preferred that the apertures through which fastening means are locatable and/or the one or more punch nail holes and/or the one or more truss nails are located on the sheet-like material such that the reinforcement plate may be fastened to the top and/or the bottom flange of an I-joist.

The reinforcement plate may further comprise one or more edge flanges upstanding from the plane of the sheet-like material. More specifically, the edge flange(s) may be upstanding from the plane of the sheet-like material at an opposing face of the reinforcement plate to the flange surrounding the opening in the sheet-like material. The edge flange(s) is/are located at an outer edge of the sheet-like material remote from the opening therein.

The edge flange(s), where present, provide additional strength and stiffness to the reinforcement plate between the top and bottom portions of the sheet-like material and thereby prevent buckling of the plate in use. It has been found that the edge flange(s), where present give a significant contribution to the overall strength of the reinforcement plate in preventing same from buckling under tension.

In embodiments of the invention, the reinforcement plate is a single piece of sheet-like material. By forming the reinforcement plate as a single piece of sheet-like material, cost savings are made in the manufacturing process when compared to reinforcement plates formed of two or more pieces. Furthermore, alignment of the reinforcement plate at the I-joist is simplified when compared to two-piece arrangements due to the alignment process being the opening against the removed portion of the I-joist as opposed to both the removed portion of the I-joist and also the two pieces of plate to one another.

In embodiments of the invention, the opening in the reinforcement plate is configured to circumscribe a large diameter opening in the web portion of an I-joist. A large diameter opening is preferably greater than 55mm diameter.

In embodiments of the invention, the reinforcement plate is locatable at one side of an I-joist.

The weakened portion is located in the web portion of the I-joist.

In embodiments of the invention the sheet-like material is formed of galvanised steel.

In use, the continuous flange about the opening in the reinforcement plate and upstanding from the sheet-like material does not contact the web portion of the I-joist to which the reinforcement plate is attached. In this way, the continuous flange does not bite into the web of the I-joist thereby further reducing its load bearing capacity. In preferred embodiments, the continuous flange about the opening in the plate is locatable approximately 2mm or more from the face of the web portion of the I-joist.

Preferably the reinforcement plate is attachable to a timber I-joist.

According to a second aspect of the invention there is provided an I-joist assembly comprising an I-joist weakened by removal of a portion of its web volume and a reinforcement plate attached thereto; the reinforcement plate comprising a sheet-like material for placement against a generally planar surface of the I-joist and having an opening therein configured to be aligned with the weakened portion of the I-joist, the opening being defined by an edge of the sheet-like material characterised in that the edge comprises a continuous flange depending therefrom and upstanding from the plane of the sheet-like material.

Preferably the reinforcement plate is according to the first aspect.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

While the terms "upper", "lower", "top" and "bottom" are used within the specification, they should be considered as no more than relative, as the plate of the present invention may be used in any orientation to suit the location of the I-joist.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 depicts a perspective view of a reinforcement plate according to an embodiment of the first aspect of the invention; Figure 2 depicts the reinforcement plate of Figure 1 in front plan view; Figure 3 is a side elevation of the reinforcement plate of Figure 1; Figure 4 is a flat profile of the reinforcement plate of Figure 1 prior to the forming of the end flanges; Figure 5 is a reinforcement plate assembly according to an embodiment of the second aspect of the invention; Figure 6 shows an end elevation the reinforcement plate assembly according to Figure 5; and Figure 7 shows a perspective view of a reinforcement plate according to an alternative embodiment of the first aspect of the invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Further, although the invention will be described in terms of specific embodiments, it will be understood that various elements of the specific embodiments of the invention will be applicable to all embodiments disclosed herein.

In the drawings, similar features are denoted by the same reference signs throughout.

Reference is initially made to Figure 1 of the drawings which illustrates a reinforcement plate, generally indicated by reference number 1.

Reinforcement plate 1 is a single piece sheet of galvanised steel having a central opening 3 therethrough.

The reinforcement plate I of the depicted embodiment is rectangular in shape and its boundaries are defined by contiguous outer edges. The outer peripheral edge comprises: a base edge 5, a top edge 7, and first and second side edges 9 and 11 connecting the base and top edges 5 and 7.

The inner peripheral edge of the reinforcement plate defines the obloid opening 3 and comprises: a base edge 13, a top edge 15, and first and second side edges 17 and 19 connecting the base and top edges 13 and 15.

Depending from the inner peripheral edge of the reinforcement plate is a continuous flange comprising: a base flange portion 21, a top flange portion 23, and first and second side flange portions 25 and 27 connecting the base and top flange portions 21 and 23. The flange is continuous about the opening 3 and is upstanding from the rear surface 29 of the plate 1 at an angle of approximately 90° thereto. The flange is formed by bending the sheet material of the plate and is integral with the rest of the reinforcement plate 1.

The reinforcement plate 1 further comprises first and second side flanges 31 and 33 depending from opposing outer edges 9 and 11 of the plate 1.

These outer edge side flanges serve to further strengthen the plate against buckling under torsional forces.

First and second side flanges 31 and 33 are upstanding from the front surface 37 of the plate I at an angle of approximately 90° thereto.

Fastening apertures 35 are located through reinforcement plate 1 proximate the upper and lower outer edges 7 and 5. In the depicted embodiment a plurality of fastener apertures 35 are located through plate 1 across the full width of the plate 1 between the first and second outer side edges 9 and 11. in embodiments of the invention it will be understood that one or more of the fastener apertures 35 may be replaced by punch nail holes, truss nails or the like.

Figure 2 clearly shows that the continuous flange about opening 3 is obloid in shape and formed by contiguous flange portions 21, 23, 25 and 27. The top, base and first and second side flange portions are joined to one another at the curved flange corner portions 39a, 39b, 39c, 39d. In this way, the flange is continuous about the opening 3.

Figure 3 is a top plan view of the reinforcement plate 1. The first and second outer edge flanges 31 and 33 are bent out of the plane of the plate 1 at an angle of approximately 90° thereto. The continuous flange about the opening 3 (not shown) is bent out of the plane of the plate 1 at an angle of approximately 90° thereto. The first and second edge flanges 31 and 33 and the continuous flange about opening 3 are, therefore, parallel to one another and bent out of opposing faces of the plate 1.

Figure 4 depicts the reinforcement plate I prior to the first and second edge flanges 31 and 33 being bent out of the plane of the plate 1 about first and second fold lines 41, 43. By way of the side flanges being integral with the faces 29 and 37 of the plate 1 additional strength is provided to the plate.

Figure 5 shows an I-joist assembly according to an embodiment of the second aspect of the invention. Top flange 47 is spaced apart from bottom flange 49 and connected thereto by web portion 51. The reinforcement plate of Figure 1 is fastened to the top flange 47 and the bottom flange 49 of the I-joist through apertures 35 in the plate. Opening 3 in the plate allows access through the plate to the duct hole 53 in the web portion 51 of the 1-joist. The top flange portion 23 provides a frictional fit against the lower surface of the top flange 47 of the I-joist and bottom flange portion 21 provides a frictional fit against the upper surface of the bottom flange 49 of the I-joist. First and second outer edge side flanges 31 and 33 provide additional strength to the plate to resist failure due to torsional forces applied thereto.

As best seen in Figure 6, the reinforcement plate I is attachable to a timber I-joist, generally denoted by reference numeral 45. I-joist 45 has a top flange 47, a bottom flange 49 and a web portion 51 spanning between the top flange 47 and the bottom flange 49.

When the reinforcement plate 1 is correctly located against the I-joist 45, the top flange portion 23 is proximate the lower face of the top flange 47 of the I-joist 45 and the bottom flange portion 21 is proximate the upper face of the bottom flange 49 of the I-joist 45. In some embodiments, the top and bottom flange portions 23, 21 of the plate 1 will form a frictional fit with the lower surface of the top flange 47 and the upper surface of the bottom flange 49 of the I-joist 45 respectively.

As can be seen in Figure 6 with particular reference to second side flange portion 19, the flange of the plate I is spaced apart from the web portion 51 of the I-joist. In this way, the flange does not bite into the web portion of the I-joist in use thereby the strength of the web portion is retained.

Although not shown in Figure 6, it will be understood that the plate 1 may be further fastened to the front faces of flanges 47 and 49 of the I-joist through fastener apertures 35.

Various modifications and improvements may be made to the forgoing without departing from the scope of the present invention as defined by the claims. For example and as depicted in Figure 7, a reinforcement plate 100 may be provided without first and second outer edge side flanges. The optional outer edge side flanges provide an additional resistance to buckling of the plate when present.

In a further modification, the reinforcement plate may include truss nails integral with the sheet-like material. In this way, the reinforcement plate may be attached to an I-joist with or without additional fasteners being required.

By way of example only, the opening 3 in the plate 1 may be 250mm breadth and 207mm height. The curved corners of the continuous flange may have a radius of curvature of 21.5°. The plate 1 may be of breadth 405mm and height 294mm. The optional side flanges 31, 33 on the plate 1 may each be of 15 to 16mm breadth. It will be understood that the given dimensions are of one specific embodiment only and may be varied according to the requirements of the I-joist and the reinforcement plate.

Claims

Claims 1. A reinforcement plate for attachment to an I-joist weakened by the removal of a portion of its web volume; the reinforcement plate comprising a sheet-like material for placement against a generally planar surface of an I-joist and having an opening therein configured to be aligned with the weakened portion of the I-joist, the opening being defined by an edge of the sheet-like material characterised in that the edge comprises a continuous flange depending therefrom and upstanding from the plane of the sheet-like material.
2. A reinforcement plate according to claim 1, wherein the opening in the sheet-like material is centrally aligned.
3. A reinforcement plate according to claim 1 or claim 2, wherein the opening is dimensioned such that the continuous flange about the opening is locatable proximate the top and the bottom flanges of an I-joist.
4. A reinforcement plate according to any one of the preceding claims, further comprising one or more edge flanges upstanding from the plane of the sheet-like material.
5. A reinforcement plate according to claim 4, wherein the edge flange(s) are upstanding from the plane of the sheet-like material at an opposing face of the reinforcement plate to the flange surrounding the opening in the sheet-like material.
6. A reinforcement plate according to any one of the preceding claims, wherein the reinforcement plate is a single piece of sheet-like material.
7. A reinforcement plate according to any one of the preceding claims, wherein the reinforcement plate is locatable at one side of an I-joist.
8. An I-joist assembly comprising an I-joist weakened by removal of a portion of its web volume and a reinforcement plate attached thereto; the reinforcement plate comprising a sheet-like material for placement against a generally planar surface of the I-joist and having an opening therein configured to be aligned with the weakened portion of the I-joist, the opening being defined by an edge of the sheet-like material characterised in that the edge comprises a continuous flange depending therefrom and upstanding from the plane of the sheet-like material.
9. An I-joist assembly according to claim 8, wherein the reinforcement plate is according to any one of claims 1 to 7.
10. A reinforcement plate substantially as herein described with reference to the accompanying drawings.
11. An I-joist assembly substantially as herein described with reference to the accompanying drawings