CA3007756C

CA3007756C - Bonded plate wood trusses

Info

Publication number: CA3007756C
Application number: CA3007756A
Authority: CA
Inventors: Ashok Ahuja
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-06-27
Filing date: 2018-06-27
Publication date: 2021-01-12
Anticipated expiration: 2038-06-27
Also published as: CA3007756A1

Abstract

Bonded truss plates are applied to any side of the truss for the specific placement locations, to provide additional strength to the joint it was designed for and additional load bearing capacity to a structural wooden product. The bonded plate wood trusses provide an innovative method of fixing the weak/crack portion of the trusses by using a steel plate bonded with an adhesive to the steel connectors of trusses. The adhesive bonding provides transfer of axial forces in the wood truss members to provide additional tensile and shear strength than that of the original truss plate which is very crucial for the transfer of the forces and the stability of the joint; and the same may be applied to the broken members of the truss or to repair incorrectly positioned trusses.

Description

[0001] TITLE BONDED PLATE WOOD TRUSSES

[0002] TECHNICAL FIELD
Bonding plate is an innovative method where the plate is made from thin galvanized steel and special adhesive is used on the plate to make a bond with the wood. The lateral resistance of the plate, tensile strength and shear strength is evaluated by the actual laboratory tests. The bonding of the adhesive is designed to transfer axial forces in the wood truss members and it has much higher tensile and shear strength than that of the original truss plate which is very crucial for the transfer of the forces and the stability of the joint. This composite action of adhesive and steel is the key to use bonded plates to fix many other issues also in the wood trusses.

[0003] BACKGROUND OF THE INVENTION
Most of the trusses in Canada and USA are manufactured with metal truss plates that are pressed into the wood members by using sophisticated truss manufacturing equipment by applying pressure on one side of the trusses. The truss plates are designed to be applied on both sides of the truss for the specific placement locations. It has been observed that many times that plate on one side of the truss is misplaced and that reduces the strength of the joint it was designed for. This situation many times is ignored by the truss manufacturer but in the long run, load bearing capacity of the roof structure is compromised, and the present invention helps curtail this issue.

[0004] One of the prior art, Russian application RU2196865, published on 20 January 2013, discloses application of the glue in a wooden trusses structure but on the wooden edge, joints and certain forces to provide extra strength to the structure, specifically on the butt joints but it does not describe the application of the glue or any type of epoxy using the bonded plates for strengthening the weak or crack portions of the trusses.

[0005] Another prior art, US patent 6148579 issued on 21 November 2000 describes the use of the "pre-braced" compression web of a wood truss of the instant invention satisfies the requirements for structural integrity of installed prefabricated wood trusses while eliminating the need for compression web bracing at the job site. The instant invention promises to reduce construction time and costs and provide a more accurately braced roof system. To eliminate having to install bracing at a job site, the instant invention makes hardware for prefabricated wood trusses which may be attached to wood web members under compression which require bracing. Such bracing may be installed while a truss is being fabricated. Hence, inspection of the compression web bracing at the job site is not required, as with prior art continuous lateral and/or "T" bracing. The hardware for pre-braced wood trusses is designed to reinforce truss web members to be placed in compression and prevent buckling when the truss receives a load. The hardware for pre-braced compression web of a wood truss is preferably made of metal and most preferably made of galvanized steel. The drawings shown were of several embodiments of the possible designs and attachment means for the hardware for the pre-braced wood trusses of this invention. In addition, a range of lengths and various gauges of steel may be used for the hardware.

[0006] Another prior art, US patent US9670676, issued on 06 June 2017 describes a truss for incorporation into a building structure includes a framework of truss members, a plurality of the truss members having a rectilinear cross-section defined by major dimensions including a width and a depth, a plurality of flat connector plates, each of the connector plates joining at least two of the plurality of the truss members by spanning the at least two of the plurality of the truss members, and at least one of the plurality of truss members having a necked-down portion that reduces one major dimension to the width or depth of an adjacent one of the plurality of the truss members to define a necked-down dimension, wherein the necked-down portion is connected with an adjacent one of the plurality of the truss members having a width or depth equal to the necked-down dimension by at least one of the plurality of connector plates.

[0007] Another prior art, CA2241715, published on 16 June 1998 describes a metal truss comprising a pair of parallel, spaced apart elongated metal tubes having rectangular cross- section, a plurality of diagonal members equally spaced along said pair of tubes for interconnecting the tubes, said diagonal members being arranged V-shaped pairs with a diagonal member of each pair being attachable on opposite the elongated metal tubes, and connector means for joining the diagonal members to the elongated metal tubes. The diagonal members each comprises an elongated plate having flanged sides and enlarged oblique end plates at each end thereof to facilitate the truss.

[0008] Another prior art, CA1188475, published on 23 February 1983 describes a wood roof truss construction capable of functioning at least to accepted standards yet being capable of erection with substantial material and labor cost savings, the improved wood roof truss comprising a bi-chord wood truss system redundantly superimposed on a single centered rod tied arch system with the tie rod being the dominating tension member and carrying a major share of the tension stress in proportion to the *load while the wood bi-chord carries a minor share of tension forces.
The web system of the truss functions to redistribute whatever imbalance and lack of symmetry occurs in the gravity loading, both systems having a common top chord and a pair of individually functioning of the bottom chords, the bottom chords being separated, free from interconnection for shear transfer except the bearing ends of the roof truss construction. Means are provided for supporting the tension rod, said means functioning also to secure the web system to the chord of the roof truss construction, totally without fixed securement of the tension rod to the webs or bottom chord. Further, an improved coupling assembly is provided for joining the bottom chord to the bearing ends of arch, and containing there within, accessible from the outside, the portion of the rod taken up and extending beyond.

[0009] Another prior art, CA2156453 published on 18th August 1995 describes one of the aspects of the invention, there is provided a reinforced wood beam having a length and a longitudinally extending upper and lower surface. The upper and lower surfaces have a plurality of reinforcements.
Each reinforcement comprises a steel strip bonded within a longitudinally extending ken. The upper and lower surfaces each has at least two kerfs extending past the original beam length. According to another aspect of the invention, the kerfs terminate intermediate at the ends of the wood beam.
According to another aspect of the invention, the kerfs are staggered along the length of the wood beam. According to another aspect of the invention, there is provided a method of manufacturing a reinforced wood beam. The method comprises the steps of cutting a plurality of longitudinally extending kerfs in an upper and lower surface of a wood beam, inserting a bead of adhesive along the length of each of the kerfs, inserting a steel strip in each of the kerfs, and allowing the bead of adhesive to harden.

[0010] SUMMARY OF THE INVENTION
This invention relates to applying bonded steel plate over the truss connector plates which when applied to any side of the truss for specific placement locations provides load bearing capacity to the wood roof truss structure and additionally strengthens the truss. The bonding of the steel plates to the truss by the adhesive provides for transfer of axial forces in the wood truss members to provide additional tensile and shear strength than which is originally present in the truss connector plate as the same is essential for the stability of the joint and the transfer of forces. This invention can also be used for the repair of the broken or cracked portion of the trusses by bonding the steel truss plate with an adhesive to the broken members of the truss.

[0011] BRIEF DESCRIPTION OF THE DRAWINGS
This invention is better understood and objects other than that set forth above becomes apparent when consideration is given to the following detailed description thereof.
Such description makes reference to the annexed drawings wherein:

[0012] Figure 1 illustrates a view of the damaged Peak Truss plate and the bonded plate inserted to repair the damage; and it also illustrates a view of the Heel truss plate misplaced and the bonded plate inserted so that the misplacement of the heel truss plate is repaired.

[0013] Figure 2 illustrates a view wherein the Truss Web is Broken, and the bonded truss plate helps in strengthening or repair of the truss as the case may be; and it also illustrates the top or bottom chord broken or truss plate placed wrongly wherein the bonded truss plate helps in repair/strengthening of the truss.

[0014] DETAILED DESCRIPTION

[0015] Referring to Figure 1 that illustrates a view of the damaged Peak Truss plate and the bonded plate inserted to repair the damage -10. Peak truss plate gets damaged as with time the load bearing capacity of the wood truss reduces, also at times when the trusses are delivered and installed on the site, they may have many members cracked or broken and it becomes cumbersome to repair them with scabs using nails or screws. The method of repairing the truss by using the bonded truss plate helps in the repair effectively as with time it causes more cracks if hammering nails are used to repair the damage. The formulated adhesive used on the bonding plate when applied on the trusses helps to strengthen the truss and thereby double the shear and tensile strength of original truss plate.
Referring to Figure 1 that illustrates a view of the Heel truss plate misplaced and the bonded plate inserted - 12 so that the misplacement of the heel truss plate is repaired. As the manufacturing process being used currently guesses the placement of the plate that is placed underneath the truss.
Therefore, at times truss manufacturer ignores this misplacement that can cause serious repercussions in the future as this reduces the strength of plate in action that was designed for various axial, compressive, tensile and shear forces. In order to repair this misplacement of the heel truss plate as shown in the Figure 1 the present invention of using of a bonding plate of thin galvanized steel along with the formulated adhesive helps to align this misplacement and this increases the shear and tensile strength.

[0016] Referring to Figure 2 illustrates a view wherein the Truss Web is Broken and the bonded truss plate - 20 helps in strengthening or repair of the truss as the case may be.
Truss web members are prone to breakage as in the long run the load bearing capacity of the truss decreases. Therefore, the present invention of the bonded plate acts as a mechanism to repair the broken truss plate. The bonded plate is a thin galvanized steel plate which is inserted in the broken web of the truss as shown in Figure 2. This invention can also be incorporated when the truss is manufactured and also can be used to repair the broken truss in order to increase the load bearing capacity of the truss. Referring to Figure 2 that illustrates the top or bottom chord broken or truss plate placed wrongly wherein the bonded truss plate helps in repair/strengthening of the truss. The bonded plate can be placed at the top or the bottom chord ¨ 22, 24, as shown in the Figure 2, this helps in the repair of the truss and it will have much higher tensile and shear strength than that of the original truss plate which very crucial for the transfer of the forces and the stability of the joint. The action of the adhesive and steel is the key to fix this issue of broken top or bottom chord or truss plate placed wrongly. The role of the bonded plate is to increase the strength of the truss which can be incorporated in the manufacturing or may be used at the time of repair.

[0017] This invention relates to wood trusses. The design and construction of trusses has in recent years advanced substantially; it is having been realized that the construction of elements of a building in a factory with the subsequent assembly of these elements on site materially reduces the cost of construction. Prefabricated trusses in shop have certain deficiencies in terms of steel connector plates on one side of the joints in the truss is placed in a altered position than it is intended for due to manufacturing process where one of the plates is placed is guessed for its placement location.

[0018] Although the preferred embodiment has been described in detail above, other modifications are possible. From the foregoing, it is observed that numerous variations and modifications may be affected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific system or method described herein is intended or should be inferred. It is of course intended to cover all such modifications as fall within the spirit and scope of the invention.

[0019] It is now apparent to a person skilled in the art that the wood trusses with steel connector plates of the present invention could be readily modified. It is understood that certain changes in style, size and components may be effective without departure from the spirit of the invention and within the scope of the appended claims.

Claims

1. The method of repairing a structural wooden truss product by providing a high tensile bonded steel plate over faces of steel truss plates at joints of said structural wooden truss products by applying adhesives on the steel truss plates and on said high tensile bonded steel plate to form a structural joint to transfer axial forces and to resist tensile, compressive and shear forces.

2. The method of repairing the truss as claimed in claim 1 which are found to be weak wherein the steel truss plate on the truss is incorrectly positioned or when the truss needs to be reinforced for extra load bearing capacity, the high tensile bonded steel plate is applied directly with adhesive on the steel truss plates of joints of the truss.

3. The method of repairing the truss as claimed in any one of claims 1-2 wherein the truss being repaired is a roof truss or floor truss.

4. The method of repairing the truss as claimed in any one of claims 1-3 wherein a repair is carried out on a construction site or in a manufacturing shop or even at a finished roof, and wherein a size of said high tensile bonded steel plate is derived with structural engineering software for bonding with steel truss plates at joints of the trusses.