AU717272B2 - Truss - Google Patents

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art:

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Name of Applicant: Mark Eliott Fisher Actual Inventor(s): Mark Eliott Fisher Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title:

TRUSS

Our Ref 519300 POF Code: 127767/329892 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1-

TRUSS

1. FIELD OF THE INVENTION The present invention relates to a truss, such as a truss for suspending lighting or other concert or performance equipment or for suspending exhibition equipment such as lighting, banners and display monitors. In particular, the invention concerns a modular truss which may be connected to other similar trusses to build a combined truss arrangement for suspending lighting or other concert or exhibition equipment at a concert or theater venue, exhibition or such like, such as on a temporary basis, in association with a touring production, during concert touring.

*ee DLMAIN Doc: 244226 1 2. DESCRIPTON OF RELATED ART INCLUDING INFORMATION DISCLOSED UNDER 37 CFR 1.97 AND 1,98 A truss may be provided with a framework comiprising initerconnected spars, the truss being elongate and having a square or triangular transverse cross section. While assembled truss arrangements of this nature are usually sufficiently strong to provide the required support to concert equipment, they take up a great deal of room once disassembled and are thus expensive to store and transport.

Onie develoPnent wtduch aim5 to overcme~ tis problem is to provide trusses in which the spars are foldable to take up less room for storage or transport.

However, the folding nature of these trusses means that they are inherently rather weak.

S 4 0 DLMAIN Doe: 2442261 3 SUMMARY OF THE INVENTION The present invention aims to alleviate the problems of the prior art.

According to one aspect of the present invention there is provided a readily transportable truss having a body which is internestable with at least two other similar trusses in a storage configuration thereof including: a first upper elongated spar and a first lower elongated spar rigidly connected parallel to each other at first and second spaced locations by a first pair of elongated members extending perpendicular between said first upper elongated spar and said first lower elongated spar; a second upper elongated spar and a second lower elongated spar rigidly connected parallel to each other at first and second spaced locations by a second pair of elongated members extending perpendicular between said second upper elongated spar and said second lower elongated spar; at -least two cross chords rigidly connecting said first upper and said 15 second upper elongated spars in a parallel arrangement to define a plane and form a top portion of said truss, said cross chord laying substantially in said plane, and said truss defining a trapezium cross section having an open aspect opposite said top portion; a first tie-bar rigidly connected between the elongated member extending 20 between said first upper spar and said first lower spar at said first location, and the elongated member extending between said second upper spar and said S"second lower spar at said first location, said first tie-bar spaced a selected ooo.

distance from and parallel to said plane defined by said first and second upper spars; a second tie-bar rigidly connected between the elongated members extending between said first upper spar and said first lower spar at said second location, and the elongated member extending between said second upper spar and said second lower spar at said second location, said second tie-bar spaced said selected distance from and parallel to said plane defined by said first and second upper spars; and each of said first and second tie-bars having a lower surface which is approximately the same length as the distance between the outside surfaces of said first and second upper spars such that said truss can be internested with a 3a similar truss by engagement of said top portions formed by said first and second upper spars with the lower surfaces of said first and second tie-bars.

The internestable nature of the truss with others which are identical or similar to it makes it possible to provide a truss arrangement made up in modules by a plurality of similar or identical trusses, which can be disassembled to a storage or transport configuration in which the volume taken up by the internested structure is minimized. This is highly advantageous since the result is that the cost of transporting the truss arrangement is minimized.

When the truss is elongate, it is possible to place one truss on one or more support trolleys and to stack several similar trusses on top of it. The trolley can be manipulated very conveniently.

The truss and trolleys may be conveniently sized and dimensioned for fitting several stacked piles of trusses alongside one another in a storage compartment, such as in a truck, standard shipping or air freight container.

15 The body of the truss of the above mentioned aspect of the invention is preferably elongate and open to an open aspect thereof, and an opposite aspect of the body is preferably internestable with the said one aspect of an identical t truss.

0 *0 o* 4 There now follows a discussion of various preferred features of the truss which may be incorporated in trusses according to either one or both of the above mentioned aspects of the invention.

The body of the truss preferably comprises a framework of interconnected spars. The spars may be tubular and preferably are of metal, although the use of various other materials, such as plastics, e.g. polypropylene or a carbon fiber or other reinforced matter, is envisaged. The spars are preferably fixed relative to one another and, when made of metal, may be fixed relative to one another by welding.

This provides a truss which is rigid and has a high amount of strength in relation 10 to its weight.

Instead of being formed as a framework of interconnected tubular spars, the oo body of the truss, may, in alternative embodiments, be made as a molded or extrusion form of material such as plastics, such as polypropylene or a carbon fiber reinforced plastics material, or metal.

15 The body may be saddle-shaped, having an elongate channel extending along the length thereof on the said open aspect, preferably substantially along the entire .o length of or entirely along the length thereof. This saddle-shaped configuration enables one truss to be stacked on top of and internested with another similar or identical one. This is a particularly volume-efficient manner in which to store trusses of elongate nature.

Preferably, the framework and form of the truss is adapted to define, in use, an elongate top and two elongate sides of the body. The top is preferably flat and spaces the two sides apart. The sides, in transverse section, are preferably tapered apart, becoming further spaced apart with increasing distance away from the top.

The truss may be configured with the flat top horizontal and the two sides extending downwardly from the top and it is envisaged that the truss will often be set up in this configuration. However, it is also envisaged that it could be set up and DLMAIN Doe: 244226 1 configured in use with the top at the side or even the bottom of the truss and, in the latter case, the sides may then extend upwardly from the top. The word top has therefore been used in this specification to describe the truss when in its most usual anticipated configuration. In the case of a molded form, the top and sides may be discontinuous, comprising a webbed framework, with webbed spars of the framework being separated by holes to reduce the amount of material required for the truss and/or to provide suitable equipment mounting locations on the truss.

Likewise, in the case of an extruded form, the amount of material required for the truss may be reduced and mounting locations provided by removing material i 10 subsequent to extrusion, to result in a webbed or holed framework, e.g. having webbed spars.

In a horizontal orientation of the top of the framework or form, each side thereof, in transverse section, may taper from the vertical by an angle of between .10 and 45 degrees, preferably being between 15 and 25 degrees, about 20 degrees 15 being preferably, the angle being 20.5 degrees in one example. In some embodiments, the angle of taper may be more than 45 degrees or less than degrees.

The framework preferably includes two spaced apart longitudinal spars on the open aspect of the body and at least one longitudinal spar on the said opposite aspect of the body. Preferably, two said longitudinal spars are provided on the said opposite aspect of the body and these are preferably interconnected to one another by a series of cross chords.

Preferably, all adjacent ones of the longitudinal spars are interconnected by cross chords, apart from the longitudinal spars of the framework of the body which are located on the open aspect thereof. The cross chords and longitudinal spars may define planar or curved surfaces of the truss. The truss may include three rectangular planar braces, each being defined by two longitudinal spars and DLMAIN Doe: 244226 1 interconnecting cross chords at the ends thereof. As well as the end cross chords, each two adjacent longitudinal members (apart from those on the open aspect) may be interconnected by diagonal bracing spars or cross chords that are perpendicular to the longitudinal length thereof.

The truss may, as an accessory, include a removable cross brace which is releasably mountable between the longitudinal spars -of the open aspect of the body, preferably by means of snap fit connectors. The removable cross brace prevents outward splaying of the longitudinal spars on the open aspect of the body which might otherwise occur with the truss subjected to substantial load. A cross brace 10 of this nature may, naturally, be employed in the case of extruded or molded forms.

When a cross brace is provided and two longitudinal spars are provided on the o opposite aspect of the truss interconnected by a series of cross chords, the two longitudinal spars of the open aspect of the body are preferably spaced apart by the same distance as two cross chord of the series of cross chords on the opposite aspect of the body, and the removable cross brace is preferably interchangeably mountable at ends thereof either between the two longitudinal spars of the open aspect or between the said two chords of the series of the cross chords. Thus, the removable cross brace may be positioned at the open aspect of the truss to strengthen it while in use and, for internesting or stacking of the truss for storage or transport, may be conveniently held in position extending in a longitudinal direction of the truss between two of the series of cross chords on the aspect of the truss opposite the open aspect.

In a most preferred embodiment, the framework has four parallel longitudinal spars, the four parallel longitudinal spars, in transverse section, having the shape of a regular trapezium, the longer of the parallel sides of the trapezium being on the open aspect of the body.

DLMAIN Doe: 244226 1 7 The longitudinal spars may be straight to provide a straight truss, or curved to provide a curved truss. In either case, all of the longitudinal spars are preferably parallel, consisting of translations of one another in three dimensional space.

The cross chords and cross brace (when provided) are preferably straight.

When the truss includes four parallel longitudinal spars, these are preferably interconnected at each end thereof by three.end cross chords which are adapted, in use, to form respective top and side end chords of the framework. The side end chords are preferably interconnected by a bracing tie-bar which is spaced from and parallel to the top end chord, each tie-bar having lower surface which is approximately the same length as or up to about 5 or 10% longer than the distance across the top of the truss adjacent the top end chord.

"In preferred embodiments, the tie-bar is connected to each side end chord a distance more than 50%, preferably more than 75%, such as about 85%, of the distance along each side end chord from the open aspect of the truss. The tie-bar not only provides bracing for the truss, but may support the truss on top of another similar truss when stacked or intemrnested, so that the side end chords of adjacent trusses do not engage one another. This is particularly important when the truss has tapered sides since it prevents the weight of trusses stacked upon one another from causing splaying of the sides of stacked trusses.

20 The truss may be provided with a catwalk deck extending along a longitudinal direction thereof. When the truss has an elongate flat top and sides, the catwalk OOO may be located adjacent the flat top, preferably located, above it, with respect to gravity.

The truss may include a handrail which is releasably mountable to the body, such as by snap fit connectors. The catwalk and handrail enable technicians or even performers to move along the truss safely, such as when it is suspended above a concert set.

According to another aspect of the invention there is provided a nod~ular truss structure which includes two trusses, each said truss being in accordance with one or both of -the above mentioned aspects of the invention, each truss being elongate and having two ends, the two trusses being joined to one another end to end.

According to another aspect of the invention there is provided a truss in accordancze with one or both of the first two other mentioned aspects of the invention, in combination with a lamp, the lamp being connected to the truss inside the body of the truss. The truss when it has an open aspect, enables a relatively large portion of the lamp mounting and other ancillary equipment to be located, in use, inside the body of the truss, thus providing an aesthetic arrangement, as is particularly important for concerts and similar performances.

outAccording to another aspect of the invention, there is provided a truss as set ou neither or both of the first two above mentioned aspects of the invention, in combination with a drape, the drape hanging from one side of the truss.

Another aspect of the invention provides a stacked truss arrangement comprising at least two trusses, each said truss being as set out in one or both of the first two above mentioned aspect of the invention, the two trusses being stacked on ::ee top of and internested with one another. The bottom one of the trusses may be supported on a trolley and, in this case, the trolley may include side supports which :20 ame adapted to prevent outward movement of bottom portions of the bottom truss.

Such movement might otherwise occur with a truss with tapered sides as discussed above, if a substantial number of similar trusses were stacked on top of it.

The present invention also envisages any combination of any of the features of the above mentioned aspects of the invention and the preferred other features discussed herein which is not specifically set out herein.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention may be carried out in various ways and several trusses for suspending concert or performance equipment in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 is a perspective view of a preferred exemplary embodiment of a lighting truss in accordance with the present invention; Fig. 2 shows the truss of Fig. 1 intemrnested for storage or transport with an o identical truss; SFig. 3 shows a schematic end view of the truss of Fig. 1 stacked on a trolley 10 with five identical trusses; Fig. 4 is a plan view of a second preferred exemplary embodiment of a lighting truss in accordance with the present invention; Fig. 5 is a schematic end view of three stacks of trusses on trolleys similar to the stack shown in Fig. 3, loaded into a truck for transport; Fig. 6 is a part top plan view of a slightly modified version of the truss of Fig. 1; S:o Fig. 7 is an end view of the truss of Fig. 1, including an optional removable cross brace; Fig. 8 is a side view of the cross brace shown in Fig. 7; Fig. 9 is an end view of the truss of Fig. 1, stacked with four similar trusses; Fig. 10 is a schematic end view of the truss of Fig. 1, with a lamp and drape mounted thereto; Fig. 11 is a part side view corresponding to Fig. Fig. 12 shows a side view of another preferred embodiment of a truss in accordance with the invention; DLMAIN Doc: 244226 1 Fig. 13 is an end view of the truss of Fig. 12; Fig. 14 is an end view of the truss of Fig. 1, showing an optional catwalk and handrail; and Fig. 15 is an end view of the truss of Fig. 1, in an inverted configuration, in combination with an optional catwalk.

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8009 9900S DLMAIN Doe: 244226_1 DETAILED DESCRIPTION OF THE PREFERRED

EMIBODIMENT(S)

As Fig. I shows, a lighting truss 10 in accordance with one exemplary preferred embodiment of the invention comprises a body 12, the body comprising a tubular spar framework 14. The framework 14 includes two straight upper longitudinal spars 16 and two straight lower longitudinal spars 18. The four longitudinal spars are parallel to each other.

The upper longitudinal spars 16 are connected to one another by two end cross cho~rds 20 uhich, together with interm:diate cross chords 22, form a series of cross chords extending between the two upper longitudinal spars, perpendicular thereto, and defining a top of the truss.

Each of the upper longitudinal spars 16 is also connected to the adjacent one of the lower longitudinal spars 18 by side end cross chords 24 and diagonal braces 26. Each of the upper longitudinal spars, defines, together with the adjacent one of the lower longitudinal spars and side end chords and diagonal braces to P which it is connected, a side of the truss.

0 0, 15 All of the spars, that is to say the upper and lowr longitudinal spars 16, 18, the end icross chords 20-, the intemediate cross chords 229 the side end cross chords 24, and the diagonal braces 26, are straight and are f ixed to one another. These spars are preferably all metal, such -as aluminum or an aluminum alloy.

It will be noted that there are no cross chords which interconnect the two lower longitudinal spars 18. The lower aspect of the truss is therefore open.

As the end view of the truss of Fig. 3 shows, the side end cross chords 24 extend outwardly as they extend away from the end cross chords 20. Overall, the truss body 12 is therefore saddle-shaped and in transverse section or end view has the shape of a regular trapezium. The open nature of the lower aspect of the truss 12 enables its upper aspect to be internested inside the lower aspect of a similar or identical truss and Fig. 3 shows six identical trusses 10 stacked on top of one another. Fig. 2 shows two trusses like the one shown in Fig. 1 stacked on top of one another. It will be noted that the internesting or stacking nature of the trusses enables a relatively large amount of the trusses 10 to be stacked for storage or transport within a set volume. This is extremely advantageous and a practical application of the ability of the trusses to stack is shown in Fig. 5 in which three stacks 10' are shown stacked on trolleys 28 on castors 30 inside the storage space 32 of a truck 34. Thus, it is possible to load a substantial number of the trusses onto one or more trolleys 28 in a stack 10' (a trolley may be provided at each *longitudinal end of the stack), and a substantial number of the trusses 10 may therefore be manhandled all together, with the minimum effort. Furthermore, the number of individual trusses 10 that can be transported in a particular storage space 32 is maximized, thereby reducing transport costs. This is particularly advantageous for lighting trusses of the type which are used during concert touring for suspending concert equipment such as lighting above performers such as bands.

The stacking principle is not only applicable to trusses 10 with straight longitudinal members 16,18, but can be embodied in curved trusses as shown in Fig. 4, where the upper 116 and lower 118 longitudinal spars are curved in plan view, but are parallel to one another. All of the spars of the body of the truss 100 are straight apart from the upper 116 and lower longitudinal spars 116,118 and reference numerals for spars equivalent to those shown in Fig. 1 have 100 added on to them in the truss of Fig. 4. The truss shown in Fig. 4 also includes optional equipment supports 190 extending between the upper 116 and lower 118 longitudinal spars, and the supports 190 may be conveniently used for mounting lighting or other equipment inside the truss 100.

DLMAIN Doc: 244226 1 13 in use, the truss 10 of Fig. 1 may be connected end to end with a similar truss by connectors in the form of yoke members 26 (see Fig. 6) mounted on the ends of the longitudinal spars on one side of the truss 10 which are interengageable with flanges 38 mounted to the ends of the longitudinal spars 16,18 on the other side of the truss 10. The flanges 38 of one truss 10 may be slid into the yokes 36 of another truss and then bolts (not shown) may-be inserted through holes 40 in the yoke members 36 and flanges 38 to secure the two trusses relative to one another.

Fig. 6 is a partial view in that the diagonal braces 26 of one side of the truss 10 are not shown in that drawing. It will be appreciated that the truss 10 of Fig. 6 is slightly modified with respect to the truss 10 of Fig. 1 in that the positioning of the :9 yoke members 36 and flanges 38 is reversed from one side of the truss to the-other, i.e. in Fig. 6, the yokes 36 are on the right side of each end of the truss when viewed from above, whereas in the truss of Fig. 1 they would be on the left if the truss were viewed from above.

~l5Fig. 8 shows a removable cross brace 42 which has at each end thereof a jaw 44. Thbe jaws 44 may be secured to the lower longitudinal spars 18 of the truss 10 by a snap fit securement. The purpose of the removable brace 42 is to prevent splaying of the lower longitudinal spars 18 of the truss 10 when the truss is under substantial load. The distance between the two lower longitudinal spars 18 is the same as the distance between the cross chords 20,22 which extend between the top longitudinal spars 16 of the truss 10. Accordingly, the cross brace 42 may be 9 removed from-the position shown in Figs. 7 and 13 where it extends between the lower longitudinal spars 18 and may be mounted between two of the cross chords 22 for storage or transport.

It will be noted that the truss 10 of Figs. 12 and 13 is a slightly modified version of the truss shown in Fig. 1, in that the truss of Figs. 12 and 13, which is 14 similar in this respect to the truss of Figs. 10 and 11, includes additional side cross chords 192.

It will be seen most clearly from Figs. 1 and 7 that the truss 10 includes, at each end thereof, a tie-bar 46 extending between the side end cross chords 24. As shown in Fig. 1, each tie-bar is parallel to and below its respective end cross chord and each tie-bar is located approximately 80% of the distance between an imaginary line joining the centers of the lower longitudinal spars 18 and an imaginary line joining the centers of the upper longitudinal spars 16. The tie-bar 46 serves as a brace to rigidify the truss 10. In addition, a lower surface 48 of the tie-bar is approximately the same length across the truss or, preferably slightly longer than, an upper surface of the truss in the region of the end cross chord The tie-bar 46 preferably has a length along its lower surface which permits the ""lower surface thereof to rest on the top of a stacked truss below, with no gap or substantially no gap created between the sides of stacked trusses (see Fig. 9).

o15 Therefore, when several trusses 10 are stacked on top of one another as shown in Fig. 9, substantially all of the weight of each particular truss is transmitted down *ag to the truss below by the engagement of the tie-bar 46 of the truss above on top of the upper surface 50 below. This prevents the lower longitudinal spars 18 of the lower trusses in the stack from splaying outwardly due to the weight of the trusses 20 above, and therefore prevents the trusses from jamming together in the stack or 0~o0 potentially damaging one another. As shown in Figs. 3 and 5, in order to prevent undesirable outward splaying of the lower longitudinal members 18 of the lowest truss 10 in the stack, the trolley 28 may be provided with side supports or side ears 52 for hindering sideways movement of the lower longitudinal spars 18 of the lowest truss.

it will be noted from Fig. 7 that, with the end cross chords 20 horizontal, the side end cross chords 24 of the truss 10 are outwardly tapered at an angle alpha which in this particular truss is 20.5 degrees from the vertical.

Turning to Fig. 14, it will be seen that a catwalk deck 54 may be secured to the truss 10 adjacent and on top of the lower longitudinal spars 16 and the end cross chords 20 and intermediate cross chords 22. The catwalk deck 54 enables a technician or performer 56 to move safely along the truss, for example when it is suspended above the ground (not shown). In addition, it will be seen that a handrail 58 may be secured to the truss by jaws 60 which engage the upper 16 and lower 18 longitudinal members.

The truss may be assembled in position in any desired orientation, with the top spars 16 having any desired orientation relative to the lower spars 18, and Fig.

0 15 shows the truss 10 in an inverted configuration, with the top longitudinal spars 16 now located at the bottom, and the bottom longitudinal spars 18 now located at :15 the top. A catwalk deck 54 is secured to the truss 10 above and adjacent to the tiebars 46, and the lower longitudinal spars 18 serve as a handrail.

Th catwalk 54 and handrail 58 are preferably removed frcn the truss 10 before @555,stacking.

Figs. 10 and 11 show that lights 62 may be mounted to the truss, with the ':20 mounting point of the lights located up inside the body of the truss 10. The open :0.:nature of the lower aspect of the truss therefore not only enables stacking, but also enables lighting or any other concert equipment to be assembled in a more aesthetic manner with mounting poles 64 and ancillaries 66 such as a housing 68 containing a lighting controller (not shown) and/or a motor (not shown) for swivelling a lamp 70 of the light, located up above the lower longitudinal spars 18. The sight- line produced by the lower longitudinal spars 18 substantially inmproves the appearance of the light 62 -and truss In addition, as shown in Fig. 10, the tapered nature of the truss permits heat sensitive material such as a drape 72 to be hung from the truss 10 and spaced a sufficient distance from the lamp 70 to avoid overheating of the lamp 70 and the drape 72.

.o e DLMAIN Doc: 244226_1

Claims (10)

1. A readily transportable truss having a body which is internestable with at least two other similar trusses in a storage configuration thereof including: a first upper elongated spar and a first lower elongated spar rigidly connected parallel to each other at first and second spaced locations by a first pair of elongated members extending perpendicular between said first upper elongated spar and said first lower elongated spar; a second upper elongated spar and a second lower elongated spar rigidly connected parallel to each other at first and second spaced locations by a second pair of elongated members extending perpendicular between said second upper elongated spar and said second lower elongated spar; at least two cross chords rigidly connecting said first upper and said second upper elongated spars in a parallel arrangement to define a plane and :form a top portion of said truss, said cross chord laying substantially in said plane, and said truss defining a trapezium cross section having an open aspect opposite 9i °said top portion; a first tie-bar rigidly connected between the elongated member extending 0e between said first upper spar and said first lower spar at said first location, and o the elongated member extending between said second upper spar and said 20 second lower spar at said first location, said first tie-bar spaced a selected distance from and parallel to said plane defined by said first and second upper oooo° spars; a second tie-bar rigidly connected between the elongated members 99 9 extending between said first upper spar and said first lower spar at said second

9., location, and the elongated member extending between said second upper spar and said second lower spar at said second location, said second tie-bar spaced said selected distance from and parallel to said plane defined by said first and second upper spars; and each of said first and second tie-bars having a lower surface which is approximately the same length as the distance between the outside surfaces of said first and second upper spars such that said truss can be internested with a similar truss by engagement of said top portions formed by said first and second Supper spars with the lower surfaces of said first and second tie-bars. 18 2. A truss as claimed in claim 1 wherein said elongated spars are preferably tubular spars. 3. A truss as claimed in claim 1 or claim 2 in which the spars include a molded or extrusion form. 4. A truss as claimed in any one of the preceding claims wherein said two upper longitudinal spars are interconnected to one another by a series of cross chords. A truss as claimed in any one of the preceding claims further including a cross brace which is readily attached and detached between the lower elongated spars of the truss. ai 15 6. A truss as claimed in claim 5 in which the lower elongated spars of the truss are spaced apart by the same distance as two adjacent cross chords of the a"aseries of cross chords connecting the upper spars of the truss, and the cross brace is interchangeably and selectively attached between either the two lower i :elongated spars or between the said two adjacent cross chords of the series of 0* 6 20 cross chords. a a a: a 7. A truss as claimed in any one of the preceding claims wherein the elongated spars are straight. a 0 8. A truss as claimed in any one of claims 1 to 6 in which the elongated spars are curved. 9. A truss as claimed in any one of the preceding claims wherein the four parallel elongated spars are interconnected at each end thereof by a cross chord and two of said elongated members to form respective top and side portions of the truss, and in which the elongated members of the framework are interconnected by a tie-bar which is spaced from and parallel to the cross chord, Seach tie-bar having a lower surface which is approximately the same length as 19 the distance across a top surface of its respective cross chord, each tie-bar being adapted to support the weight of the truss when stacked upon another identical truss by engagement with a top surface of the truss in the region of the cross chord of the truss below the stack. A truss as claimed in any one of the preceding claims including a catwalk deck attached to and extending parallel to said elongated spars.

11. A truss as claimed in claim 10 wherein the catwalk deck is located adjacent the top of the truss.

12. A truss as claimed in any one of the preceding claims including a handrail which is removably mountable to the body. °S 15 13. A truss according to any one of the preceding claims including a second °6 similar truss to form a modular truss structure, the two trusses being joined end to end in serial alignment. AS "14. A truss as claimed in any one of the preceding claims in combination with a o 20 drape, the drape hanging from one of said elongated spars of the truss. 0 S 5555

15. A truss according to any one of claims 1 to 8 including a tie-bar rigidly oleo connected between an elongated member of said first pair and an elongated 5 member of said second pair and parallel to said cross chords.

16. A truss according to any one of claims 1 to 8 including at least two tie-bars each connected between an elongated member of said first pair and an elongated member of said second pair and adapted to support the weight of the truss when stacked upon another similar truss by engagement with said top portion of the truss.

17. A truss according to claim 16 wherein each tie-bar has a lower surface which is approximately the same length as the distance across said top portion of said truss.

18. A truss according to any one of the preceding claims wherein said cross chords are connected perpendicular to said spars.

19. A truss according to any one of the preceding claims wherein said pair of elongated members rigidly connecting said upper and lower elongated spars are perpendicular to said upper and lower elongated spars. A truss according to any one of claims 1 to 19 further including another elongated member rigidly connecting said upper and lower elongated spars other than perpendicular to said upper and lower elongated spars.

21. A truss according to any one of the preceding claims wherein said rigidly S.i .connected spars, elongated members, cross chords, and tie-bars are welded. .22. A truss substantially as herein before described with respect to any one of lilt 20 the embodiments illustrated in the accompanying drawings. 0909 DATED: -17 January 2000 PHILLIPS ORMONDE FITZPATRICK S• Attorneys for: MARK ELIOTT FISHER MARK ELIOTI FISHER