GB2463126A

GB2463126A - Box beam jointing system

Info

Publication number: GB2463126A
Application number: GB0909981A
Authority: GB
Inventors: William Andrew Makinson
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-09-05
Filing date: 2009-06-10
Publication date: 2010-03-10
Anticipated expiration: 2029-06-10
Also published as: GB0909981D0; GB2463255A; GB0816162D0; GB2463126B

Abstract

The invention relates to a jointing system for connecting either a single box beam 1 to a fixed point or a plurality of box beams to each other to form a rigid framework which may be used as a building or other structure. The jointing system comprises a first locating member 5 or members fitted into the hollow end of the box beam 1. The system further comprises a connection member consisting of a second locating member 9 fast with a fixed point or forming part of a matrix (12 figure 6) of a plurality of second locating members 9, wherein the second locating members 9 have a form which is engageable with the first locating member or members 5, and wherein a securing means secures the first and second locating members together. The box beam 1 may be formed from equally sized wooden patio decking members (2 figure 2a) with tongue and grooved mitred corner lock joints (3 figure 3). The first and second locating members may have male and female inter-engaging elements and the fastening means to secure the first and second elements together may be a nut 6 and bolt 11.

Description

BOX BEAM JOINTING SYSTEM

This specification relates to the construction of buildings, structures and the like, using box beam elements and prefabricated principles. It is particularly suited to wooden framed buildings but is not exclusive to this application.

The use of box beams as construction members is well known and such beams are widely used because they possess high bending strength, rigidity and load carrying capacity.

Reinforced concrete box beams are commonly used for long-span road and rail bridges.

The same principle is known for wooden framed buildings and, in many of these, the wood of these structural members is visible internally and used decoratively, harmonising with wooden panelling, to create an overall impression.

The use of wooden box beams in conventional brick or wooden buildings is known and construction principles such as joist hangers are also known. However, where the box beams form part of the internal decorative features of such buildings, conventional metal hangers, which would be visible, are unacceptable. Metal, angled plates, located in the hollow centres of the box beam, would impair the load carrying ability of the beams and, again, are unacceptable. Methods to overcome these traditional construction methods could be devised but they would add to construction times and costs and some options could intrude into the usable living space.

Pre-fabncated building techniques, where structural members, such as rolled steel joists, are manufactured in a factory for assembly on site, are known, as is the manufacture of panels to form the walls and floors between adjacent joists. Such techniques are suitable for a range of essentially standard buildings, with scope for limited design changes available at relatively little cost. However, this pie-fabrication principle is not applicable to wooden box beam framed buildings, all of which have to be individually designed and made. This adds to the time and cost and so tends to reduce the availability of this essentially green building option.

Thus, there is a need for a simple, reliable method of connecting wooden box beams together so that prefabricated members can be manufactured in a workshop for assembly on site.

According to the invention, there is provided a jointing system for connecting a box beam to a fixed point or a plurality of box beams one to another comprising:-i) a box beam or a plurality of box beams; ii) a first locating member(s) securely fittable into the hoUow end of the I each box beam; iii) a connecting member consisting of a second locating member fast with the fixed point or a matrix consisting of a plurality of second locating members fast with each other, said second locating member(s) having a form engageable with said first locating member(s); and iv) means to secure each first locating member to a second locating member, characterised in that the I a plurality of box beam(s) may be connected to form a rigid framework which may be used as the basis for a building or other structure.

According to a first variation apparatus of the invention, the box beam is formed from four equally sized wooden planks so that the box beam has a square section.

According to a second variation of the apparatus of the invention, the planks are patio decking members.

According to a third variation of the apparatus of the invention, the box beams are formed with tongue and grooved, mitred corner lock joints.

According to a fourth variation of the apparatus of the invention, the first and second locating members have the forms of male and female interengaging elements so that any first locating member may engage with any second locating member.

According to a fifth variation of the apparatus of the invention, the first and second locating members have the forms of square cup' alignment elements.

According to a sixth variation of the apparatus of the invention, a first locating member is recessed into the hollow end of a box beam and secured fast thereto.

According to a seventh variation of the apparatus of the invention, the means of securing the first and second locating elements together is a nut and bolt.

According to an eighth variation of the apparatus of the invention, the nut is fast with the first locating element.

According to a ninth variation of the apparatus of the invention, the second locating member is fast with a structural member and aligned with the interengaging face accessible for fitting the box beam thereto.

According to a tenth variation of the apparatus of the invention, the second locating member is fast with one or a plurality of other second locating member(s) forming a matrix of connecting members, with the interengaging faces accessible for fitting box beams thereto.

According to an eleventh variation of the apparatus of the invention, the alignment of adjacent second locating members relative to each other in a matrix I matrices is / are at a right angle(s).

According to a twelfth variation of the apparatus of the invention, means are provided in I on the structural member or the matrix of connecting members to give access to fit and tighten the nut I bolt securing the first and second locating members together.

According to a thirteenth variation of the apparatus of the invention, a first locating member is provided at both ends of the box beam so that pluralities of box beams and second locating members fast with structural members I matrices of connecting members may be used to construct a structural framework.

According to a fourteenth variation of the apparatus of the invention, means are provided to increase the resistance to the effects of tensile forces acting wholly or partly in the axial direction along the beam, which might otherwise tend to pull first locating members away from attachment to the box beams.

According to a fifteenth variation of the apparatus of the invention, the means to increase the resistance to the effects of tensile forces acting wholly or partially in the axial direction along the beam include means to grip part(s) of the inside surface of the box beam.

According to a sixteenth variation of the apparatus of the invention, the means to grip parts of the inside surfaces of the box beam include ratchets, teeth, spring tines and I or angled members.

According to a seventeenth variation of the apparatus of the invention, the means to grip parts of the inside surfaces of the box beam include member(s) fast with the first locating cup and stuck to the inside of the box beam.

According to an eighteenth variation of the apparatus of the invention, the means to increase the resistance to the effects of tensile forces acting wholly or partially in the axial direction along the beam include means within or passing through the wooden sides of the box beam.

According to a nineteenth variation of the apparatus of the invention, the means within or passing through the wooden sides of the box beam include dowels located axially within the wooden sides.

According to a twentieth variation of the apparatus of the invention, the means within or passing through the wooden sides of the box beam include nails, screws, bolts or the like passing through the sides of the box beam and engaging with member(s) located inside the box beam and fast with the first locating member.

According to a twenty first variation of the apparatus of the invention, the means to increase the resistance to the effects of tensile forces acting wholly or partly in the axial direction along the beam is / are a tie rod(s) fast with and extending between the first locating members fitted at the two ends of the I each box beam.

In a preferred application of the invention, the box beam is made of patio decking planks and the first locating member is a square section, dished cup fixed in a recess at one, or both, ends of the beam. The second locating member is another square section, dished cup, such that the two cups fit together in the manner of a male female engagement. A nut and bolt is used to secure the two cups together, with the nut captive on the beam side of the first locating cup and the bolt passing through aligned holes in the two cups to engage the nut. Second cups may either be used singly, fast with structural members, or in groups, fast with each other, to form a connecting matrix. A maximum of five second cups, arranged on five faces of a cube, is the largest connecting matrix likely to be used.

Using the principle of the invention, box beams and single and I or a matrix(matrices) of second connectors, a large framework may be constructed to form the basis of a building or structure.

A number of means may be used to increase the resistance of the connections between the first cups and the beam to axial tensile forces, which might otherwise tend to pull the first cup away from the beam. These means include devices to grip parts of the inside surfaces of the box beam and devices which go into the wood of the sides of the box beam, or pass through it, and engage with members fast with the first cups as well as axial tie rods extending between the two first cups at both ends of the beam.

For a clearer understanding of the invention and to show how it may be put into practice, reference will now be made, by way of example only, to the accompanying drawings, in which:-Figure 1 is a sectional elevation of a standard size decking plank; Figure 2 is a sectional elevation of a box beam made from four of the planks shown in Fig. 1, with tongue and groove, mitred corner lock joints; Figure 3 is an enlarged detail of the tongue and groove, mitred corner lock joint of the Fig. 2 box beam; Figure 4 is a sectional elevation of the fitting of a first locating cup into the end of a box beam of Fig. 2; Figure 5 is a sectional elevation of the end of a box beam of Fig. 2, with a first locating cup fitted, mating with a second locating cup; Figure 6 is a sectional plan view of a connecting matrix, according to the invention, with three of the Fig. 5 box beams ends fitted and a fourth one being fitted; Figure 7 is a sectional elevation of a first method of increasing the resistance to tensile forces on the box beam connection of Fig. 6, wherein ratchet teeth engage with grooves on the inside of the box beam; Figure 8 is a sectional elevation of a second method of increasing the resistance to tensile forces on the box beam connection of Fig. 6, wherein angled spring tines engage with the inside surface of the box beam; Figure 9 is a sectional elevation of a third method of increasing the resistance to tensile and shear forces on the box beam connection of Fig. 6, wherein a square sectioned plug is stuck to the inside of the box beam; Figure 10 is a sectional elevation of a fourth method of increasing the resistance to tensile forces on the box beam connection of Fig. 6, wherein dowels are fitted into the wood of the sides of the box beam; Figure 11 is a sectional elevation of a fifth method of increasing the resistance to tensile forces on the box beam connection of Fig. 6, wherein angled members engage with nails driven through the sides of the box beam; Figure 12 is a sectional elevation of a sixth method of increasing the resistance to tensile forces on the box beam connection of Fig. 6, wherein a square section member inside the box beam engages with screws passing through the sides of the box beam; In the following description, the same reference numeral is used for the same component or for different components fulfilling an identical function.

Referring to Figs. 1-3, four standard sized planks 2 are used to form a box beam I with tongue and groove, mitred corner lock joints, as shown Fig. 3. The full axial lengths of the corner joints 3 are glued to form a strong, composite box beam section. Any sized planks 2 are possible but 145 mm wide by 21 mm thick patio decking sections, giving a square section beam 1 are preferred; these can be of hard or soft wood. Rectangular section beams (not shown) are equally possible.

Fig. 4 shows one end of a box beam section 1 with a recess 4 and a locating cup 5 being fitted 7 into a glued 4A recess 4. Locating cup 5 preferably has the square, conical, dished form shown, similar to that of the locating cups used as the upper ends of metal framed pallet structures, provided so that one metal pallet may be stacked on top of a lower one.

x 120mm square cups 5 are ideal for use with 145 x 145mm box beams 1. As shown (Fig. 4) a nut 6 is welded 8 to the male base of locating cup 5 and aligns with hole 6A in cup 5 so that a bolt 11 (Fig. 5) may be passed therethrough and screwed into nut 6.

Fig. 5 shows how first locating cup 5, recessed 4 in the end of box beam 1, engages 10 with second locating cup 9 and how cups 5 and 9 are secured together via nut 6 and bolt 11. Also shown in Fig. 5 are parts of further second cups 9, welded 14 together to form part of a connecting matrix 12. Fig. 6 shows five second locating cups 9A-E welded 14 together mutually at right angles to form connecting matrix 12 having the form of five sides of a cube. The sixth side (uppermost in Fig. 6)is empty, to allow access to fit and tighten bolts 1 IA-E. Fig. 6 shows three box beams I attached to second locating cups 9A, 9B and 9D respectively. A third box beam 1 is being attached 10 to second locating cup 9C.

Chamfered corners 13 are provided where beams 1 abut.

The form of connecting matrix 12 is that of a cube with all second locating cups 9 mutually at right angles to each adjacent cup 9. This would be the normal form of connecting matrix 12 for most buildings or structures but other angles are equally possible, e.g. for pitched roof beam connections at the eaves of a building.

Because of their two vertical and two horizontal elements around central void 2A (Fig. 2), box beams I are exceptionally good at carrying bending loads and possess high degrees of rigidity. They are commonly used for structural members, e.g. particularly as reinforced concrete road bridges. Wooden box beams are particularly useful as structural members in (green) wooden buildings where the beams and infill panelling are used for decorative, as well as structural, purposes.

One potential weakness with the principle of the invention is that axial, tensile forces 34, 34A (Fig. 7) may tend to break the glued bond 4A between beam 1 and the first locating cup 5. It is a feature of the invention that means are provided to reinforce the bond 4A between beam 1 and cup 5 to withstand the sorts of tensile forces which might occur naturally in wooden framed buildings, e.g. due to wind loading or encastré structures.

In addition to axial tensile loading, e.g. caused by external loads on the building, tensile forces also occur due to internal loads, such as the weight of heavy furniture on beams 1.

These loads cause bending moments, generating additional tensile forces in the top member of box beam 1, compressive forces in the bottom member and composite forces in the side members. Shear forces are another aspect of the complex reaction to loading on beams 1 but members inserted into the interior of beam 1 at or near the ends of beams 1 can greatly increase the load carrying capability. Box beams 1, according to the invention, are intended for use both as horizontal beams, where bending is the main problem, as well as vertical columns, where buckling forces are likely to be encountered.

Before considering how the bond between cup 5 and planks 2 of composite beam I may be strengthened to resist axial tensile forces 34, it is necessary to understand intimately the nature of the wood 2 and joints 3 forming beams 1. Wood has a fibrous nature and is strongest when loaded across the grain. It is weakest when opposing tensile forces are applied normally to the grain as this has the effect of pulling apart adjacent fibres. Joints 3 are glued, mitred tongue and grove designs (Fig. 3). Glue and glued joints are strongest in compression and shear but weak in tension. As shown in Fig. 3, the mitred tongue and groove joint has faces mutually at right angles to each other and also at 45°; the effect of this is that, whatever external load is applied to a box beam 1, there will always be a number of faces in direct compression and shear to more-than-compensate for any potential weaknesses due to any faces loaded in tension.

Another point to note is that box beams 1 are integral structures of four beams and internal stresses, such as warping over time, in one plank 2 are often balanced by an equal and opposite effect in the plank on the opposite side of the beam 1. Thus, the box beam of the disclosure is an extremely strong, substantial element, ideal for structural members of buildings, especially where they form a decorative part of the overall effect or is an integral part of the overall visual effect. The box beam and jointing system of the invention is intended for quick assembly of permanent buildings, similar to that for metal-framed buildings. It is not appropriate for light, temporary structures, which are regularly erected and dismantled, e.g. for exhibitions, at displays and the like.

In view of these strengths to resist external forces, it is essential to eliminate any significant internal forces acting outwardly, e.g. forces 35 as shown in Fig. 2. As the grain runs along the length of planks 2 (Figs. 4 and 5), the views of Figs. 1, 2 and 3 are onto the end of the grain, so that forces 35 are effectively bursting forces' acting to rip apart adjacent wood fibres and tear asunder joints 3. The mode of failure of joints 3 could be failure of the glue or, more likely, tearing of a tongue away from its parent wood. The only method of reinforcing beams I against bursting forces 35 would be to place a metal band around beam I in way of the lines of action of forces 35. However, external bands would be unsightly and highly detrimental to the visual impact of an all wooden box beam construction where the grain and appearance of natural wood is a key feature of such buildings.

It is known that some types of metal furniture are formed of hollow square or rectangular tubes and the joints are formed by members, which are expanded to grip the internal faces of these tubes. The gripping members usually have high coefficient of friction faces in contact with the internal tube faces. The axial strength of this type of joint depends on the magnitude of the radial force exerted by the expanded members onto the internal faces of the tubes, according to the basic Friction Laws. Clearly, as box beams of the invention are not designed to withstand large bursting forces 35, this type of connection I reinforcement is not appropriate here. Instead, a range of means have been developed to enhance the strength of connection of cups 5 to beams 1 and so reinforce connections of beams 1 to connecting matrices 12.

Figs. 7-12 show typical examples of how this tensile strengthening may be provided. In Fig. 7 a square section tube 15, with a flanged end 18, is fast with the flange of cup 5.

Conventional welding 19 and I or spot welding 1 9A are used to secure cup 5 to flange 18 of tube 15. As shown, ratchet teeth 16 on tube 15 engage with grooves 17, pre-cut into planks 2 before beam 1 was assembled. When cup 5 and tube 15 are fitted, tube 15 is pushed into the square central void 2A of beam 1 until ratchets 16 engage with grooves 17, when the flange face will be hard against glue 4A in recess 4. The effect of the application of tensile loading 34A to cup 5 will be to spread the load via ratchets 16 uniformly around planks 2 at the end of box beam 1. Tube 15 will also resist shear loading on beam 1.

A variation of the principle of Fig. 7 is shown in Fig. 8 where angled spring tines 21, fast with tube 20, engage with the inside surfaces 2B of box beam 2 and perform a parallel role to that of ratchets 16. Like tube 15, tube 20 resists shear loading.

In Fig. 9, a square section plug 22, with a threaded bore 23, is shown fitting into the hollow void 2A of box beam 1. A glue bead 24 is fitted into an annular groove 25 under angled spring tines 26. As the plug 22 is pushed into void 2A, glue bead 24 is ruptured allowing the glue to smear evenly the inside surface of box beam 1. When locating cup 5 is fitted onto glue 4A in recess 4, plug 22 is pushed to its proper location where tines 26 engage with groove 27. The glue from bead 24 sticks the circumference of plug 22 to the inside 2B of beam 1. When this design of end connection is secured 11 to second locating cup 9, bolt 11, passing through hole 6A, will engage with thread 23 to lock members 9, 5 and 22 firmly together and against tensile forces 34, 34A. Due to its tight fit, plug 22 will provide significant resistance to shear loading.

Though not shown, a simple axial tie rod, extending between the two end cups 5 at both ends of a single beam 1, is another design option. This would be achieved by screwing one end of the tie rod into nut 6 or thread 23, when assembling that end member (Figs. 4 or 9). The other end of the tie rod (not shown) would be located in a spider (not shown) to align it with hole 6A and terminate in a tapped sleeve (not shown) so that cup 5 at the other end could be inserted and a bolt 11 fitted and screwed into the tapped sleeve to secure and apply internal tension to beam 1.

Fig. 10 shows the use of a dowelled section 18 fast 19, 1 9A with cup 5. Dowel elements 27, fast with flange 18, are glued into pre-drilled holes in planks 2 to so that the axial tension 34, 34A is again spread over a large volume of the wood of the end portion of beam 1.

In Fig. 11, a square sided tube 28 is fast 29 with cup 5. Angled members 30 contact the inside surface 28 of planks 2 when the cup-tube assembly is fitted 4A into recess 4. Nails 31 are then driven through the sides 2 of beam 1 and (initially) contact leading angled faces 30A, exerting a force pushing assembly 30, 28 and 5 to the right thus compressing cup 5 more tightly into recess 4 and onto glue 4A. As shown, nails 31 then penetrate angled members 30, locking the assembly 30, 28 and 5 firmly in place to resist both tensile and shear forces. Members 30 may be of any suitable material of construction, e.g. wood, plastic, nylon, metal, etc. Fig. 12 is a variation of the principle shown in Fig. 11 where a square sectioned tube 32, via flange 18, is fast 19, 1 9A with cup 5. When fitted 4A into recess 4, holes are drilled through wood 2 and tube 32 and countersunk screws 33 are inserted, as shown.

With the principles taught in Figs. 11 and 12, nails 31, screws 32 or bolts (not shown) would preferably be through faces of beam I which are not visible, i.e. so that the nail, screw or bolt heads would not show and spoil the decorative effect of the wood. However, if this is not possible or if nails 31, screws 33 or bolts (not shown) are required in all four sides to give an even reaction force, the nail, screw or bolt heads could be recessed and covered with appropriate fillers or wooden discs (not shown) so as not to impair the visual effect.

The above examples are indicative of the means of increasing the resistance to tensile forces 34, 34A and shear loading (not shown). They are not an exhaustive list and the skilled man will be aware of variations of the means taught and of other equivalent means

all falling within the scope of the disclosure.

The invention taught offers an improved means by which wooden framed houses and structures may be constructed. With the growth in green technologies and the trend to the use of natural materials, with low or zero carbon footprints, the invention makes a significant contribution to ecological principles. The wide range of applications of the principle, and variations of it, will be apparent to skilled people, all falling within the scope of the invention.

Claims

Claims:- 1. A jointing system for connecting a box beam to a fixed point or a plurality of box, beams one to another comprising:-i) a box beam or a plurality of box beams; ii) a first locating member(s) securely fittable into the hollow end of the / each box beam; iii) a connecting member consisting of a second locating member fast with the fixed point or a matrix consisting of a plurality of second locating members fast with each other, said second locating member(s) having a form engageable with said first locating member(s); and iv) means to secure each first locating member to a second locating member; characterised in that the / a plurality of box beam(s) may be connected to form a rigid framework which may be used as the basis for a building or other structure.
2. A jointing system for box beams, as claimed in claim 1, wherein the box beam is formed from four equally sized wooden planks so that the box beam has a square section.
3. A jointing system for box beams, as claimed in claims 1 or 2, wherein the planks are patio decking members.
4. A jointing system for box beams, as claimed in claims 1-3, wherein the box beams are formed with tongue and grooved, mitred corner lock joints.
5. A jointing system for box beams, as claimed in any preceding claim, wherein the first and second locating members have the forms of male and female interengaging elements so that any first locating member may engage with any second locating member.
6. A jointing system for box beams, as claimed in claim 5, wherein the first and second locating members have the forms of square cup' alignment elements.
7. A jointing system for box beams, as claimed in claims 5 or 6, wherein a first locating member is recessed into the hollow end of a box beam and secured fast thereto.
8. A jointing system for box beams, as claimed in claim 7, wherein the means of securing the first and second locating elements together is a nut and bolt.
9. A jointing system for box beams, as claimed in claim 8, wherein the nut is fast with the first locating element.
10. A jointing system for box beams, as claimed in any preceding claim, wherein the second locating member is fast with a structural member and aligned with the interengaging face accessible for fitting the box beam thereto.
11. A jointing system for box beams, as claimed in any preceding claim, wherein the second locating member is fast with one or a plurality of other second locating member(s) forming a matrix of connecting members, with the interengaging faces accessible for fitting box beams thereto.
12. A jointing system for box beams, as claimed in claim 11, wherein the alignment of adjacent second locating members relative to each other in a matrix I matrices is I are at a right angle(s).
13. A jointing system for box beams, as claimed in claims 10-12, wherein means are provided in I on the structural member or the matrix of connecting members to give access to fit and tighten the nut I bolt securing the first and second locating members together.
14. A jointing system for box beams, as claimed in any preceding claim, wherein a first locating member is provided at both ends of the box beam so that pluralities of box beams and second locating members fast with structural members / matrices of connecting members may be used to construct a structural framework.
15. A jointing system for box beams, as claimed in any claim, wherein means are provided to increase the resistance to the effects of tensile forces acting wholly or partly in the axial direction along the beam, which might otherwise tend to pull first locating members away from attachment to the box beams.
16. A jointing system for box beams, as claimed in claim 15, wherein the means to increase the resistance to the effects of tensile forces acting wholly or partially in the axial direction along the beam include means to grip part(s) of the inside surface of the box beam.
17. A jointing system for box beams, as claimed in claim 16, wherein the means to grip parts of the inside surfaces of the box beam include ratchets, teeth, spring tines and / or angled members.
18. A jointing system for box beams, as claimed in claim 16, wherein the means to grip parts of the inside surfaces of the box beam include member(s) fast with the first locating cup and stuck to the inside of the box beam.
19. A jointing system for box beams, as claimed in claim 15, wherein the means to increase the resistance to the effects of tensile forces acting wholly or partially in the axial direction along the beam include means within or passing through the wooden sides of the box beam.
20. A jointing system for box beams, as claimed in claim 19, wherein the means within or passing through the wooden sides of the box beam include dowels located axially within the wooden sides.
21. A jointing system for box beams, as claimed in claim 19, wherein the means within or passing through the wooden sides of the box beam include nails, screws, bolts or the like passing through the sides of the box beam and engaging with member(s) located inside the box beam and fast with the first locating member.
22. A jointing system for box beams, as claimed in claim 15, wherein the means to increase the resistance to the effects of tensile forces acting wholly or partly in the axial direction along the beam is / are a tie rod(s) fast with and extending between the first locating members fitted at the two ends of the I each box beam.
23. A jointing system for box beams, as described in and by the above description with reference to the accompanying drawings.