NZ505263A - Structural threaded bracing bar system - Google Patents

Abstract

A bracings system for structures includes a threaded bar (16) of the type having unidirectional screw thread, mounting brackets (10) at each end of the bar and threaded nuts securing the bracket at each end of the bar. One of the nuts is secured to the bar to prevent relative rotation whereby the bar may be tensioned by relative rotation between the bar and a rotatable nut (19). The rotatable nut (19) may be formed integrally with one of the brackets (10).

Description

NEW ZEALAND Patents Act 1953 Patents Form No. 5 No PQ1065 Date: 18 June 1999 COMPLETE SPECIFICATION "STRUCTURAL BRACING SYSTEM" We, SPEEDIBOLT PTY. LTD. (ACN 062 110 221), an Australian Company, of 43 Morrisby Street, Geebung, Queensland, 4034, Australia hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement. r,10,-"TIP/ 0'1 OFNZ 1 9 jyft 2323 STRUCTURAL BRACING SYSTEM This invention is concerned with a structural bracing system, bracing elements and a method of bracing a structure.

Particularly, although not exclusively, this invention is concerned with bracing systems for diagonal bracing of building structures and includes within its scope tensionable bracing systems and a locking system for nuts employed with threaded bars.

It is common practice to provide bracing support in steel and timber framed structures and foundations to form a triangulated stiffening to resist wind loads and otherwise to restrain structural members comprising the building and/or foundation framework.

Typically, bracing is embodied in wall frames, across rafters and other roofing structures and is connected to load bearing members in the structure. Normally a combination of tension and compression members is used to form a pin jointed framework which takes wind loads from a wall structure through the bracing framework to the foundations.

Tensionable bracing members are currently selected frorrv- (a) continuous threaded steel rod with a variety of attachment means; (b) plain steel bar with welded turnbuckles; (c) threaded steel bar with right and left hand threads on opposite ends to accommodate turnbuckles; (d) threaded steel bar with "D" brackets.

Another type of brace comprises a right angle section steel member with spaced mounting apertures punched or drilled at opposite Ui~ v L 1 9 JUN 22m i oc^'"!u?n| ends.

The abovementioned members are attached to supporting rafters or structural columns by a variety of means including:- (i) "D" shaped brackets which are fitted into slotted apertures in the 5 rafters or columns; (ii) bolts extending through end plates on the tensionable member into cleats attached to the supporting members; (iii) bolts extending through the bracing member into cleats attached to the supporting members.

The angle section brace suffers the disadvantage that it is not readily adjustable on site to accommodate variations in fabrication tolerances which commonly occur in steel framed buildings. This usually necessitates drilling of additional apertures or enlargement of existing apertures in either the bracing member or the supporting member. 15 Apart from adding substantially to labour costs, this is often difficult or awkward to achieve in a safe manner and can compromise the integrity of the building structure. Moreover, the capacity of the angle section brace is reduced by the reduced section area and the fact that the section is connected eccentrically through one flange of the angle section. 2 0 Screw threaded bracing members have the advantage of allowing adjustable attachment of mounting members to accommodate variances in the positioning of hold down bolts or the like as well as variances in the positioning of supporting members such as columns or the like.

The use of screw threaded bracing members facilitates erection as the adjustable mounting permits an increase in length of the bracing member to assist in lifting and positioning the member between connection points on support members. Any sag in the brace member is removed by tensioning the member by adjustable mounts such as turnbuckles having left and right handed threads.

The use of adjustable bracing members thereby eliminates the necessity for drift pins and other rigging tools commonly used to accommodate small variances in fixed attachment points associated with angle bracing members.

Notwithstanding the relative advantages and disadvantages of adjustable screw threaded bracing members and non-adjustable angle bracing members, angle form bracing members are widely used due to the limited tension capacity of traditional screw threaded rods which is a function of the capacity of the thread on the bar and/or the threaded mounting members.

In screw threaded rods where the thread is cut into the outer surface, this leads to a significant reduction in thread capacity.

In contrast, for threads produced by thread rolling processes, this loss of section is reduced somewhat as the thread is rolled up from a smaller diameter rod.

Regardless of the means by which the thread is formed, tension capacity in the rod is limited to thread capacity. Moreover, the material strength of thread - rolled members is limited to that of a steel grade which can be thread-rolled on conventional thread-rolling equipment unless the product is later subjected to heat treatment which would then render the product uneconomical.

It is an aim of the present invention to overcome or alleviate at least some of the disadvantages associated with prior art bracing 5 systems.

According to one aspect of the invention there is provided a bracing system for structures, said bracing system including:- an elongate bar member having a unidirectional screw thread extending at least over opposite end portions thereof; a bearing member fixedly securable adjacent one end of said tension member and, in use, rotatable therewith; a first mounting bracket rotatably securable adjacent said one end of said tension member by said bearing member; and, a second mounting bracket rotatably securable adjacent an opposite end of said tension member by screw threaded engagement between said tension member and a screw threaded tensioner associated with said second mounting bracket Suitably said tension member comprises a thread-rolled steel member. 2 0 Preferably said tension member is formed by a cold rolling process.

Preferably said tension member has a unidirectional thread extending over the entire length thereof.

Most preferably the unidirectional thread is formed as upstanding projections with upright substantially sided walls.

Suitably said tension member includes unthreaded diametrically opposed flat surfaces extending longitudinally thereof.

Suitably the thread is formed as part helical ribs having a trapezoidal cross section.

The bearing member may comprise a screw threaded member engageable over a threaded end of said tension member.

The bearing member may be fixedly secured to said tension member for rotation therewith by any suitable means such as by welding, a lock nut or a mechanical fastener extending between the bearing member and the tension member.

Suitably, the bearing member has a bearing face, in use, to rotatably bear against said first mounting bracket The first mounting bracket suitably includes one or more mounting apertures for mounting to a support member of said structure.

The screw threaded tensioner may be formed integrally with or separately from said second mounting bracket.

Suitably, the second mounting bracket includes an integrally formed screw threaded aperture to permit rotatable screw threaded engagement with said tension member.

Preferably, the second mounting bracket includes a screw threaded tensioner engageable over said tension member, said screw threaded tensioner, in use, being secured against rotation relative to said second mounting bracket.

The second mounting bracket may include one or more mounting apertures for mounting to a support member of said structure.

According to another aspect of the invention, there is provided a method of installation of a tensionable bracing member to a building structure, said method comprising the steps of:- attaching to a first support member of a building structure a first mounting bracket which rotatably locates one end of an elongate unidirectionally screw threaded tension member by a bearing member fixedly secured adjacent said one end of said screw threaded tension member; said first bracket providing, in use, a bearing surface against which said bearing member can rotate; attaching to a further support member spaced from said first support member a second mounting bracket which rotatably locates an opposite end of said tension member in a screw threaded tensioner associated therewith, said screw threaded tensioner being non rotatable relative to said second mounting bracket; and effecting relative rotation between said screw threaded tensioner and said screw threaded tension member to apply a desired tension between said first and second mounting members.

According to a further aspect of the invention there is provided a lockable nut system for threaded steel bar, said lockable nut system comprising a screw threaded nut rotatably engageable on said threaded steel bar; and 8 a locking member slidably engageable on said threaded steel bar, said locking member being adapted in use to resist rotation about said bar, said nut and said locking member being axially engageable whereby said locking member prevents rotation of said nut on said bar.

The locking member may be adapted to resist rotation by a screw threaded fastener extending between said locking member and a surface of said bar.

Most preferably said locking member includes parallel side walls engageable with parallel side walls of said bar.

If required said nut and said locking member are axially engageable by one or more socket and spigot formations on respective adjacent ends of said nut and said locking member.

According to still further aspects of the invention there are provided mounting brackets for use with the system and method according to the invention.

In order that the invention may be more fully understood and put into practical effect, reference will now be made to preferred embodiments of the invention illustrated in the accompanying drawings in which:- Fig. 1 shows one form of mounting bracket for use with the invention.

Fig 2 shows an exploded perspective view of components of the bracket of Fig. 1.

Fig. 3 shows a perspective view of the components of Fig. 2 in an assembled state.

Fig. 4 shows mounting brackets according to an alternative embodiment of the invention.

Fig. 5 shows a preferred form of thread-rolled tension member for use with the invention.

Fig. 6 shows a lockable nut system according to the invention.

Fig. 7 shows side and end views of the nut of Fig. 6.

Fig. 8 shows side and end views of the sleeve of Fig. 6.

Referring to Figs. 1 to 3 there is shown a mounting bracket 10 having a pair of body members 11 each with a mounting aperture 12 for securing bracket 10 to a support member of a building structure.

Bracket 10 has assembly apertures 13, 14, the purpose of which will be described later, and a locating aperture 15 to rotatably locate a threaded tension bar 16 of the type having diametrically opposed flat, unthreaded surfaces 16a extending along the length thereof. This type of bar is often used in reinforced concrete structures, earth anchors or the like.

Also formed in bracket 10 is a shaped aperture 17 adapted to locate either of internally screw threaded elements 18 or 19 As shown in Figs. 2 and 3, bracket 10 is conveniently assembled from identical body members 11 formed by brake pressing, forging or the like Body members 11 are conveniently joined by cup headed carriage bolts and nuts 20, 21 respectively.

Referring back to Fig. 1, it will be seen that when bearing element 19 is engaged over the screw threaded end of bar 16 and secured thereto by a grub-screw, roll pin or like mechanical fastener extending through aperture 22, it will be free to rotate in aperture 17 as bar 16 is rotated.

The end 19a of the hexagonal headed portion 23 of element 19 thus forms a bearing surface engageable with the bracket 10 where it forms an upper end 15a to aperture 15.

Alternatively, it will also be seen that if elongate internally screw threaded hexagonal tensioning nut 18 is engaged over the end of bar 16 in aperture 19, the opposed flats 18a of nut 18 will engage against the opposed side walls 17a of aperture 17 and thus secure tensioning nut 18 from rotating.

To install the tensionable bracing system according to the invention, an assembled bracket 10 is located over one end of bar 16 which is cut slightly oversize for the distance between mounting points on spaced support members of a building structure.

A bearing element 19 is then secured over the free end of bar 16 in aperture 17 by a mechanical fastener or even by welding if required An identical bracket 10 is then located over the opposite end of bar 16 with a tensioning element 18 secured thereto and located in aperture 17 With the thus assembled tensionable bracing system supported at opposite ends, one of the brackets 10 is secured via aperture 12 to a respective structural supporting member and the aperture 12 of the bracket at the opposite end of bar 16 is aligned, if required, with a mount 11 on the other structural supporting member by rotating the free bracket 10 with its captive tensioning nut 18 Once aligned the free bracket 10 may then be secured to its respective supporting member mount.

When both brackets 10 have been secured to respective supporting members, bar 16 may be tensioned to remove sag or to align a building structure by simply rotating bar 16 with a spanner engaged over the opposing flats 16a.

As bar 16 rotates, bearing element 19 rotates in its respective mounting bracket 10 while tensioning element 18 is restrained against rotation.

Fig. 4 shows an alternative embodiment of the invention comprising a bearing bracket 25 as shown in Fig. 4A and a tensioning bracket 26 as shown in Fig. 4B.

In Fig 4A, bearing bracket 25 comprises a cast or forged bracket body 27 with a mounting aperture 28 formed therein.

Located within body aperture 29 is a bearing nut 30 in the form of a hollow internally threaded cylindrical body 31 with a necked bearing surface 32. In use necked bearing surface 32 locates in a recess 33 surrounding an end aperture 34 for receiving the end of a threaded bar (not shown) An aperture 35 is provided in nut 30 to enable mechanical fixing of nut 30 to the tensionable bar for rotation therewith by any suitable fastening means such as a grub screw, roll pin, bolt or the like.

In Fig 4B a tension bracket 26 comprises a body 36 having a mounting aperture 37 and a body aperture 38. 12 An axially extending bar receiving aperture 39 has an internal thread to engage over the thread of the tension member (not shown).

The bearing bracket 25 and tension bracket 26 of Figs. 4A and 4B respectively operate in substantially the same manner as the system described with reference to Figs 1 to 3 and may be installed in a similar fashion.

While standard threaded bar may be employed with the invention, the rounded cross-sectional profile of the threads does not provide optimum tension capacity.

For this reason, it is preferred to utilise with the invention a more substantially profiled thread similar to an "Acme" style thread.

Fig. 5 illustrates portion of a threaded bar 40 having a planar face 41 extending longitudinally of the bar on diametrically opposed sides thereof.

The thread comprises part helical ribs 42 extending over the diametrically opposed past circular portions 43 of bar 40, the ribs having a generally trapezoidal cross section as illustrated at the end 44 of each part helical rib 42.

Threaded bar of the type illustrated in Fig. 5 is employed widely in the mining industry for chemically anchored rock bolts and, as shown, comprises a single start thread.

Possibly the greatest advantage of the present invention is the substantial cost savings which may be effected by utilising the tensionable bracing system according to the invention.

Apart from the readily apparent labour savings in ease of assembly and installation, it is expected that substantial material savings can be achieved while still maintaining a specified strength. It is believed , for example, that where a prior art M16 machined thread rod may have been specified as a bracing member, the present invention will permit the use of M12 threaded bar. Similarly, for other sizes of machined thread rod, the present invention should permit the use of threaded bar one size less than that specified for a particular application.

Figs. 6-8 show a nut locking system which may be employed with the bracing system according to the invention. It should be understood however that the nut locking system may be employed with any other use of threaded bar of the type described in Fig. 5 wherein a threaded nut is employed with the bar and a convenient means of locking the nut as required.

In the drawings nut 50 is a conventional long bodied nut utilised with bar 51 having a thread 52 extending generally in radially opposite directions and a pair of generally planar side walls 53 therebetween. A pair of slots 54 is formed in, one or both end walls 55.

A locking member 56 has a cross sectional aperture with a shape complementary to the cross sectional shape of bar 51 such that the locking member is slidable therealong but is prevented from rotation by engagement of planar side walls 57 of the sleeve with the side walls 53 of the bar. The locking member 56 includes a pair of spigot like projections 58 axially engageable with slots 54 thereby effectively locking nut 50 14 against rotation on the bar 51 In many applications such as diagonal or upright bracing, earth anchors or the like, the locking member 56 may be maintained in engagement with nut 50 under the influence of gravity. Where it is not possible to rely on gravitational forces to maintain engagement, a screw threaded fastener 59 or the like may be utilised to prevent disengagement between the nut 50 and locking member 56.

It will be readily apparent to a skilled addressee that many modifications and variations may be made to the invention without departing from the spirit and scope thereof.

For example, a very simple embodiment of the invention may comprise a bracing system incorporating a threaded bar of the type illustrated in Fig. 5 with a pair of simple angle brackets having an aperture in each limb thereof.

One angle bracket may be connected at one end of the bar by a threaded nut which is mechanically secured to the bar by welding or by a locknut.

A similar bracket is secured at the other end of the bar by a threaded nut in which the bar can rotate. The nut itself is prevented from rotation relative to the bracket by positioning the bar aperture in one limb closer to the inner face of the other limb whereby a facet of the hexagonal nut lies against that inner face or by using the locking nut system of Figs. 6-8.

The installation of the bracing system as described above is substantially the same as the method of installing the system of Fig. 1 or Fig. 4.

In another modification, the locking member for the lockable nut system may comprise a planar dis-like member having a central aperture complementary to the cross sectional shape of a bar of the type generally shown in Fig. 5 whereby relative rotation between the bar and disc is prevented. The disc has one or more axially extending tabs which can be bent down with a hammer to engage in the slots 54 of nut 50.

In a still further modification of the sleeve-like locking member 56 of Figs. 6-8 or the disc-like member described above, may include spigots or tabs with enlarged ends engageable in a slot or slots in a nut 50, the slot or slots having complementary shapes to the enlarged end spigots or tabs, which when urged into the slots by a hammer or the like, secure the nut and locking member against axial separation.

Throughout this specification and claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers.

Claims (28)

16 Claims

1. A bracing system for structures, said bracing system including:- an elongate bar member having a unidirectional screw thread extending at least over opposite end portions thereof; a bearing member fixedly securable adjacent one end of a tension member and, in use, rotatable therewith; a first mounting bracket rotatably securable adjacent said one end of said tension member by said bearing member; and, a second mounting bracket rotatably securable adjacent an opposite end of said tension member by screw threaded engagement between said tension member and a screw threaded tensioner associated with said second mounting bracket

2. A bracing system as claimed in claim 1 wherein said tension member comprises a thread-rolled steel member.

3. A bracing system as claimed in claim 1 or claim 2 wherein said tension member is formed by a cold rolling process.

4. A bracing system as claimed in any one of claims 1 to 3 wherein said tension member has a unidirectional thread extending over the entire length thereof.

5. A bracing system as claimed in any preceding claim wherein the unidirectional thread is formed as upstanding projections with upright substantially sided walls.

6. A bracing system as claimed in any preceding claim wherein said tension member includes unthreaded diametrically opposed flat surfaces intellectual property office of n.z. 5 NOV 2001 RECEIVED 17 extending longitudinally thereof

7. A bracing system as claimed in any preceding claim wherein the thread is formed as part helical ribs having a trapezoidal cross section.

8. A bracing system as claimed in any preceding claim wherein the bearing member includes a screw threaded member engageable over a threaded end of said tension member.

9. A bracing system as claimed in any preceding claim wherein the bearing member is fixedly secured to said tension member for rotation therewith.

10. A bracing system as claimed in claim 9 wherein said bearing member is fixedly secured to said tension member by a lock nut or a mechanical fastener extending between the bearing member and the tension member.

11. A bracing system as claimed in claim 9 wherein said bearing member is fixedly secured to said tension member by axial engagement between said bearing member and a sleeve member mounted slidably and non rotatably on said tension member.

12. A bracing system as claimed in any preceding claim wherein the bearing member has a bearing face, in use, to rotatably bear against said first mounting bracket

13. A bracing system as claimed in any preceding claim wherein the first mounting bracket includes one or more mounting apertures for mounting to a support member of said structure.

14. A bracing system as claimed in any preceding claim wherein the 18 screw threaded tensioner is formed integrally with or separately from said second mounting bracket.

15 A bracing system as claimed in claim 14 wherein the second mounting bracket includes an integrally formed screw threaded aperture to permit rotatable screw threaded engagement with said tension member.

16. A bracing system as claimed in any one of claims 1 to 13 wherein the second mounting bracket includes a screw threaded tensioner engageable over said tension member, said screw threaded tensioner, in use, being secured against rotation relative to said second mounting bracket.

17. A bracing system as claimed in claim 16 wherein the second mounting bracket includes one or more mounting apertures for mounting to a support member of said structure.

18. A method of installation of a tensionable bracing member to a building structure, said method comprising the steps of> attaching to a first support member of a building structure a first mounting bracket which rotatably locates one end of an elongate unidirectionally screw threaded tension member by a bearing member fixedly secured adjacent said one end of said screw threaded tension member; said first bracket providing, in use, a bearing surface against which said bearing member can rotate; attaching to a further support member spaced from said first support member a second mounting bracket which rotatably locates an 19 opposite end of said tension member in a screw threaded tensioner associated therewith, said screw threaded tensioner being non rotatable relative to said second mounting bracket; and effecting relative rotation between said screw threaded tensioner and 5 said screw threaded tension member to apply a desired tension between said first and second mounting members.

19. A lockable nut system for a bracing system according to any one of claims 1 to 18, said lockable nut system comprising:- a screw threaded nut rotatably engageable on said threaded steel bar; 10 and a locking member slidably engageable on a threaded steel bar, said locking member being adapted in use to resist rotation about said bar, said nut and said locking member being axially engageable whereby said locking member prevents rotation of said nut on said bar. 15

20. A lockable nut system as claimed in claim 19 wherein said locking member has a non-circular cross-section aperture generally complementary to a non-circular cross-sectional shape of said bar.

21. A lockable nut system as claimed in claim 19 or claim 20 wherein the locking member has a screw threaded fastener extendable between said 20 locking member and a surface of said bar.

22. A lockable nut system in any one of claims 19 to 21 wherein said locking member includes parallel side walls engageable with parallel side walls of said bar.

23. A lockable nut system as claimed in any one of claims 19 to 22 intellectual property OFFICE OF N.Z. 5 NOV 2001 RECEIVPn 20 wherein said nut and said locking member are axially engageable by one or more socket and spigot formations on respective adjacent ends of said nut and said locking member

24. A lockable nut system as claimed in any one of claims 19 to 23 wherein said locking member is a tubular member.

25. A lockable nut system as claimed in any one of claims 19 to 23 wherein said locking member is a disc-like member.

26. A lockable nut system as claimed in any one of claims 23 to 25 wherein said socket and spigot formations respectively comprise an enlarged end element and a necked aperture, said socket and spigot formations, when engaged, preventing axial separation of said nut and said locking member.

27. A bracing system substantially as hereinbefore described with reference to the accompanying drawings.

28. A method of installation of a tensionable bracing member substantially as hereinbefore described with reference to the accompanying drawings. 29 A lockable nut system substantially as hereinbefore described with reference to the accompanying drawings. DATED this Sixteenth day of June 2000 SPEEDIBOLT PTY LTD By their Patent Attorneys FISHER ADAMS KELLY A bracing system for structures includes a threaded bar of the type having generally planar opposite side walls, mounting brackets at each end of the bar and threaded nuts securing the brackets at each end of the bar. One of the nuts is secured to the bar to prevent relative rotation whereby the bar may be tensioned by relative rotation between the bar and a rotatable nut. The rotatable nut may be formed integrally with one of the brackets.