EP2406434A1

EP2406434A1 - Truss girder and method for constructing the same

Info

Publication number: EP2406434A1
Application number: EP10751060A
Authority: EP
Inventors: Kim Heglund; Tore TØNDEVOLD
Original assignee: Juralco AS
Current assignee: Juralco AS
Priority date: 2009-03-09
Filing date: 2010-02-17
Publication date: 2012-01-18
Also published as: WO2010104396A1; WO2010104397A1

Abstract

The present invention relates to a truss girder (10), for example intended to form a transom in a traffic gantry, where the truss girder (10) is formed with triangular, quadrangular or polygonal shaped cross sectional area, produced of a material suitable for extrusion, and comprising at least an upper chord (13) and a lower chord (14) interconnected by means of inclined braces (16), the chords (13,14) being fabricated separately and thereupon fixed together along their corner edges by means of said braces (16) and having corner elements (15) provided with parallel, outwards projecting fins or projections (31 ) in spaced relation, extending preferably along the entire length of said corner elements (15), and that the inclined brace (16) is extruded, given a shape which is complementary the shape of the space between said fins or projections (31 ), and that the inclined brace (16) and said chords (13,14) being fixed together by means of clamping or clip means (19) locking the inclined brace (16) on to said fins or projections (31 ) of the chord (13,14). The fins (31 ) of the chord (13,14), at portions intended to be connected to the corresponding part of the brace (16), are provided with recesses (39) or projections on the fins or extensions, projecting down into or up from the fins (31 ), while the braces (16) at contact points (17) are provided with projections extending out from the braces (39), or recesses formed in the bracing respectively, said recesses or projections (39) on the fins (31 ) of the chord (13,14) and fins or recesses of the bracing (16) being configured to co-function forming a locking effect against movement of the bracing (16) in axial direction with respect to the chord (13,14). Further the present invention relates also to a method for fabrication of such truss girder (10).

Description

TRUSS GIRDER AND METHOD FOR CONSTRUCTING THE SAME

Technical Field

The present invention relates to a method for production of a truss girder having a triangular, quadrangle or a polygonal cross sectional shape, produced of extruded material and comprising at least an upper chord and a lower chord which are interconnected by means of braces and with a large distance between the corners edges of the truss girder; where the unit forming the truss girder, such as the chords, are produced separately and subsequently assembled and fixed together at the corners.

The invention relates also to a truss girder, for example produced by means of a method described above.

Background for the Invention For traffic gantries of such type it is from a traffic point of view desired that the gantries shall be designed in such way that they cause as little damages as possible to human beings involved and the vehicle during a possible collision.

Since the motorways become wider and improved, and due to the need and the requirements for improved and additional traffic information, there exists an increasing need for larger and larger gantries, both with respect to length and load carrying capacities. Such increasing dimensions of the gantries require larger and larger girders crossing the motorway in order to carry its own weight. In addition, the gantries have to be dimensioned for carrying larger payload to be supported by the gantries. Hence, it is also a need for making the gantries as light as possible and still maintaining the structural integrity, strength and load carrying capacities.

Further, there is a need for robust structures which may be able to carry large loads and to resist the moments acting on the structure at any time, without causing the gantry to collapse when exposed to such forces. As an example it should be appreciated that the traffic signs and the traffic auxiliaries supported by the gantry may be very heavy and have a large wind exposed area. Further, said signs and/or auxiliaries may be eccentrically positioned and the maximum wind forces acting on the gantry may be formidable. The signs will thus impose formidable moments on the load carrying truss girder, produced by the wind loads acting on such equipment.

WO 2006/031126, belonging to the applicant, describes a collision safe frame for large traffic gantries, the frame comprising a plurality of legs, each supported at their lower end by a foundation, while at their upper end, each leg supports one or more transverse transoms, girders or the like, intended to carry traffic signs and/or lights, or the like. The transom used is in the form of a truss girder made of extruded aluminium, for example of the type sold under the trademark Lattix®.

Reference is also made to the co-pending application PCT/NO2008/00301 , filed by the applicant, the content of which hereby being included by the reference.

When designing and fabricating such truss girders of extruded aluminium, the moment capacity is limited by the height and/or width of the truss girder. Further, for such type of solutions, it is limited how far apart the two side profiles may laterally be pulled away from each other without causing yield in the node material. Further, it is also a need for improving the methods for designing, fabricating and assembling conventional truss girders of a type other than the Lattix® girders.

Summary of the invention

An object of the invention is to provide an improved traffic gantry which will be able to carry and resist all forces and bending moments appearing in the gantry, caused by weather, wind and the bending moment acting on the gantry and other means and auxiliaries supported by the gantry.

Another object of the invention is to provide a traffic gantry having increased load carrying capacity and structurally strength without the need of increasing the weight of the gantry to the same extent.

A still further object is to provide a method for simple and rational assembling of such traffic gantries.

A still further object of the invention is to provide a truss girder produced from extruded materials, where the height of the distance between two adjacent chords may be increased substantially without a corresponding increase of the weight of the truss girder. An even further object of the present invention is to provide a traffic gantry which may be transported and de-livered in a flat packed state, for example to be assembled in situ where the gantry is to be erected or in the vicinity of such installation site. A still further object of the invention is to provide a traffic gantry which in a cost saving manner may be transported from the production plant to the assembly site or installation site on conventional trucks, lorries or vessels.

Another object of the invention is to provide a truss work formed of chords and intermediate brace(s), made as separate units and then rigidly fixing the brace(s) to the chord(s) at a number of nodes using clamps or clips in such way that relative movement between the chord(s) and the brace(s) is prevented both in axial and any lateral direction.

The objects according to the present invention may be achieved by a truss girder and a method for manufacturing such truss girder as further defined by the independent patent claims.

Alternative embodiments and preferred solutions according to the invention are defined by the dependent claims.

One embodiment of the truss girder, particularly adapted to form a transom in a traffic gantry, formed with triangular, quadrangular or polygonal shaped cross sectional area and preferably produced of a material suitable for extrusion, comprises at least an upper chord and a lower chord interconnected by means of inclined braces. The distances between the corners of the truss work girder are large and the units forming the truss girder, such as the chords, are fabricated separately and thereupon fixed together along their corner edges. The units forming the chord are provided with parallel, outwards projecting fins or projections extending preferably along the entire length of said unit, and the inclined brace is preferably extruded, given a shape which is complementary the shape of the space between said fins or projections. The inclined brace and said unit is fixed together by means of clamping or clip means locking the inclined brace on to said fins or projections on the chord. Fins on chord are at the portions intended to be connected to the corresponding part of the bracing provided with recesses into the fins or extensions projecting up from the fins, while the bracings at corresponding nodes are provided with projections extending out from the bracing, or recesses formed in the bracing respectively. Said recesses or fins on the chord, and fins or recesses on the bracing, when assembled, are configured to co-function forming a locking effect against axial movement of the bracing with respect to the chord. The fins or projections on the chord, at their foot on the main body of the chord, may also be provided with one or more recesses intended to cooperate with corresponding outwards projecting bead or lips on the free arms of the clamping or clip means, preventing movement of the braces in direction laterally outwards from the chord. According to an embodiment of the invention, the clamping or clip means at an end supported by the chord may be provided with a foot extending laterally out from the clamping or clip means, while the chord is provided with a corresponding recess provided with an end stopper, on the protrusion, said recess being configured to receive said foot, preventing the clamping or clip means to swing sideways out from the chord when in installed and locked position.

According to a further embodiment, one or more locking bolt(s) extending trough aligned hole(s) through both the fins or projections and the corresponding parts of the bracing is used to prevent relative movement between the chord and the bracing at a node. The inner surface and said space between pairs of fins or projections, and the corresponding shape of the profile cross section of the brace, may also be provided with recesses or the like, in order to prevent relative rotational movement of the braces outwards from the chord.

Each clamping or clip means may comprise two separated elements attached to each side of the bracing profile, and said clamps or clips may be formed of two separate elements which are hinged together at one end and designed for locking to the chord at the opposite end, using bolts or the like.

At least an upper chord and a lower chord may be interconnected by means of inclined braces, providing a large distance between the corners of the truss girder. The units forming the truss girder, such as the chords and bracing, may be fabricated separately and then assembled, the inclined brace, being in the form of a continuous, elongated corrugation or zigzag shaped unit which is brought in correct position with respect to a chord. One side of the corrugated or zigzag shaped unit is attached to said chord at a plurality of node positions along the chord and the inclined brace by means of suitable clamping or clip means for clamping and/or bolting the inclined brace to the chord at said nodes. The nodes of the bracing may be brought into correct position with the corresponding sections of the chord, whereupon the projections extending outwards from the profile of the bracing, alternatively the recesses on the bracing, is brought into interacting contact with the corresponding recesses, alternatively the extensions on the fins of the chord, and then locked together by means of the clamping or clip means locking the bracing to the chord, so that any relative movement between the bracing and the chord(s) is prevented.

Said connection(s) between the inclined brace and the chord may in addition be improved by means of locking methods, such as riveting, bolting and/or by means of gluing, welding rolling with or without inwards projecting point deformation, surface deformation or the like. The brace may be in the form of straight units with skewed end surface(s) where said recesses and/or the projections of the braces may be arranged in the skewed end surface(s).

According to an embodiment of the invention, the brace is provided with one or more outwards projecting fin(s) arranged along the edges, intended to lie in the same plane as the fins on the corner elements, said fins on the brace also being provided with recesses or projections, at least at each end of said brace. Further, the respective clip(s) for securing the brace(s) to the adjacent corner may be provided with recesses configured to co-function with the corresponding projections or recesses on said edges of each brace. Said clip(s), brace(s), and the said fin(s) on the corner element may preferably be provided with bore(s), configured to receive a locking means, such as bolt and nut, for locking brace(s) further to the corner element.

Further, the fins or projections on corner element of the chord, at their foot on the main body of the chord may also provided with one or more recesses intended to cooperate with corresponding outwards projecting fins or ribs on the free ends of the clamping or clip means, preventing movement of the braces in direction laterally outwards from the chord. An essential advantage of the solution according to the present invention is that the solution makes it possible to manufacture a truss girder which no longer is dependent on the inherent limitations in chord height or girder dimensions which otherwise are implied in the more conventional truss girders produced by extruding. Another essential advantage is that the truss girder may be fabricated as separate units, suitable for flat packing and hence may be assembled at the site where the gantry is to be erected, or in close vicinity of such site. In such way the cost of transportation is reduced while it will be far less expensive and much simpler, both to manufacture and assemble such structure. In spite of the increased dimensions of the gantry the weight will not increase correspondingly, making it possible to use the conventional crane capacity as previously used for prior art gantries.

Due to the new design, greater flexibility with respect to the size of the traffic mean to be supported by the gantry, is also achieved.

Short Description of the Drawings

Embodiments of the present inventions shall now be described in more detail referring to the drawings, where:

Figure 1 shows a front view of a gantry, e.g. in-tended to be used in conjunction with traffic information on a motorway;

Figure 2a shows a side view of one embodiment of a truss girder forming part of the gantry shown in Figure 1 ;

Figure 2b shows an end view of an assembled truss girder according to one embodiment of the invention, seen perpendicularly in the longitudinal direction of the truss girder, said girder having a square cross sectional shape;

Figure 2c shows an end view of an alternative cross sectional shape of a truss girder; said girder having a trapezoidal shape;

Figure 3a shows a side view of a second embodiment of an element forming part of a truss girder according to the invention; Figure 3b shows a corresponding end view of an assembled truss girder, showing an assembly of two elements as shown in Figure 2a and two elements as shown in Figure 3a; Figure 3c shows a variant of the alternative embodiment shown in Figure 3a; Figure 4a-4f shows different views and sections of a first embodiment of the clamping or clip means according to the present invention, where Figure 4a shows a section in part of the bracing, seen in perspective, fixed to a chord; Figure 4b shows an exploded view in perspective of the various parts forming part of the node section shown in Figure 4a; Figure 4c shows in perspective a vertical section between the clamping or clip means and the chord; Figure 4d shows a vertical section through the clamping or clip means and the chord; Figure 4e shows in enlarge scale a section through the upper part of the chord, the bracing and the clips or clamps according to the present invention; and Figure 4f shows part of the chord and the bracing in an assembled state prior to attachment and interlocking by a clamping or clip means; Figure 5a-5c shows various views and a vertical section through a second embodiment of the clamping or clip means according to the present invention, where Figure 5a shows in perspective a vertical section in part through a clamping or clip means fixing a bracing to a chord; Figure 5b shows a vertical section in part through the view shown in Figure 5a; and Figure 5c shows the node in an exploded view; Figures 6a-6d shows various views and a vertical sections though a node applying on a third embodiment of the clamping or clip means according to the present invention; where Figure 6a shown in perspective a typical section in part through a bracing clamped to the chord: Figure 6b shows a vertical section of the assembly shown in Figure 6a; Figure 6c shows an exploded view in perspective of the node applying this third embodiment of the clamping or clip means; and Figure 6d shows in perspective a section in part of an assembled chord and bracing;

Figures 7a-7d shows various views and a vertical sections through a node based on a fourth embodiment of the clamping or clip means; where Figure 7a shows in perspective a section in part of an assembled node; Figure 7b shows in perspective an exploded view of the node shown in Figure 7a; Figure 7c shows in perspective in part of a section through the assembled node shown in Figures 7a and 7b; and Figure 7d shows a vertical section through the node; Figure 8 shows schematically an alternative embodiment of the present invention, provided with straight braces; Figure 9 shows schematically in enlarged scale a view of a node comprising a lower chord and two straight braces, indicating also the configuration and shape of the clips and the recesses and/or projections;

Figure 10 shows schematically a vertical section through the node, also indicating that the clips are in the form of flat plates;

Figure 11 shows schematically, in an exploded view parts of a chord and the lower end of a brace, together with a clip according to the present invention; and

Figure 12 shows the node in an enlarged scale, showing the chord, the two braces and the clips or clamps in an assembled position..

Detailed Description of an Embodiment of the Invention

Figure 1 shows a view of a gantry 10, for example used in connection with traffic information, extending across and above a motorway. The gantry 10 comprises for example inclined, supporting legs 11 , arranged in pairs, at least at each side of the motorway and preferably also in the mid shoulder(s). A truss girder 12 extends across the motorway, supported by pairs of legs 11. The middle pair 11 is inclined outwards and downwards from the truss girders 12, while the pairs of legs 11 at the end also are inclined in the longitudinal direction of the gantry 10. The gantry 10 shown in Figure 1 may for example be of a type as described in WO 2006/031126, belonging to the applicant, the content of which hereby being included by the reference. The traffic information may for example be large illuminated information signs or the like.

Figure 2a shows a side view of a part of a truss girder 12 designed to extend across the motorway. As shown in the Figure, the truss girder 12 comprises an upper chord 13 and a lower chord 14. The truss girder 12 according to the embodiment shown has a quadrangular cross sectional shape, where the upper chord 13 comprises two upper corner sections 15 and inclined braces 16 extending between said upper two corner sections 15. Correspondingly, the lower chord 14 comprises two corner sections 15' and inclined braces arranged between said lower corner sections 15'. Corresponding inclined braces 16 extend also between the upper chord 13 an the lower chord 14 at each corner section 15,15'. Each corner section 15,15' is formed of extruded metal, such as for example aluminium, and has preferably uniform cross sectional area along its entire length. One embodiment of the corner section 15,15" is shown in more details in Figures 2b, 2c and 3b and will described in further details below.

Each inclined brace 16 is also formed of an extruded metal, such as for example aluminium, also having uniform cross sectional shape along its entire length. The blank intended to form the inclined braces 16 is also extruded in straight lengths, and then bent or formed into a more or less zigzag shaped or a more or less undulated form. The shape of the inclined braces will be described in further details below in connection with Figure 3. Clips or clamps 19 fix the undulated or zigzag shaped braces to the corner sections 15,15' at points or nodes 17 where the parts of the braces 16 are in contact with the corner sections 15,15'.

Figure 2b shows a view of the end of a truss girder 12 comprising four corner profiles 15, 15' 14 and four inclined braces 16. The cross section shown has a quadrangle, equal sided shape. Figure 2c shows a vertical section through a corresponding truss girder 12, where the cross sectional shape is trapezoidal.

Figure 3a a shows an alternative embodiment of an element forming a side, such as an upper chord 13, of the truss girder 12. The essential difference compared to the solution shown in Figure 2a is that two different bracing elements 16 are used, these being interconnected by nodes 29 by means of a modified clip or clamp solution 27.

Figure 3b shows an end of a truss girder 12, formed of four corner profiles 15,15' for example corresponding to the ones shown in connection to Figure 2a and which will be described in further details below. Two opposite sides are further formed of single inclined braces 16, corresponding to the one shown in Figure 2a, while two other opposite sides are formed of two inclined braces 16, fixed and rigidly connected in nodes 29, for example by means of modified clips or clamps 19. A second alternative of such assembled inclined braces may be formed by strings of straight profiles which are partly split and where the zigzag shaped is achieved by pulling the straight profiles outwards in lateral direction.

Figure 3c shows an alternative embodiment of the solution shown in Figure 3a, where the difference being the design of the node 29. The nodes 29 are formed by extruding the two strings, intended to form the inclined bracings 16, and then by slotting, punching or milling away material so that there only is a metal connections between the two strings where the nodes 29 are designed to be, whereupon the strings are pulled apart laterally outwards, thereby creating the double zigzag pattern.

Figure 4a-4f shows different views in perspective of a part of the chord 13 and sections of a first embodiment of the clamping or clip means 19 according to the present invention, where Figure 4a shows in perspective the node 17, showing the bracing 16, fixed to a chord 15; Figure 4b shows in perspective an exploded view of the various parts forming a part of the node 17 shown in Figure 4a; Figure 4c shows in perspective a vertical section through the clamping or clip means 19, the chord 15 and the brace 16 in an assembled state; Figure 4d shows a vertical section through the clamping or clip means 19 and the chord 15; Figure 4e shows in enlarge scale a section through the upper part of the corner section 15, the brace 16 and the clamps or clips 19 according to the present invention; and Figure 4f shows details of a part of the corner section 15 and the bracing 16 prior to attachment and interlocking by a clamping or clip means 19.

As indicated in Figure 4a the corner element 15 of the chord is an elongated body, preferably made of extruded aluminium. It should be appreciated that only a short portion of the corner element 15 is shown in the Figures below. As such, the corner element 15 may have any suitable shape, serving the intended purpose for establishing an adequate node 17. The elongated corner element 15 may be tubular, preferably provided with a vertical dividing, reinforcing wall 30. Further, along two of its side surfaces, the corner element 15 is provided with outwards extending pairs of fins or ribs 31 , said pairs of fin 31 preferably running along the entire length of the corner element 15. Along other side(s) of the corner element 15, the corner element 15 is provided with internal and/or externally pairs of recesses, channels 32 or the like, such ducts recesses or channels 32 being open in a direction outwards away from the interior of the corner element 15. The purpose of such open channels or recesses 32 is to allow for proper securing of heavy bodies (not shown), such as traffic signs, information carriers, lights, or the like. Each of the outwards projecting fins or ribs 31 may be along their inner or outer surfaces provided with a bead 34, the bead 34 having a trapezoidal cross section area, with smaller width at the end closest to the free end of the rib 31 , and largest width at the opposite end. Said bead 34 is designed to provide a locking effect, preventing movement of the brace 16 and clamp or clip 19 perpendicularly with respect to the longitudinal direction of the rib 31 when the clamp or clip 19 is snapped on to the fin 31 and past the bead 34. As shown in Figure 4e the clip or clamp 19 may on its lower inner or outer wall be provided with a corresponding recess or dent 35 designed to cooperate with the bead 34 for obtaining the locking effect of the clamp or clip 19.

Further, according to the embodiment shown in Figure 4a-4f, and more clearly shown in Figure 4e, the lower, free end of the clip or clamp 19 may be provided with thin fins or ribs 33 extending perpendicularly out from the free ends of the clamp or clip 19, the thickness of such fins 33 being smaller than the remaining parts of the clamp or clip 19, thereby providing certain elasticity. The end of each thin ribs 33 is designed to be in locking contact with small protrusions 36, thereby preventing movement outwards of the lower end of the clamp or clip 19 and perpendicularly with respect to the longitudinal axis of the legs of the clip or clamp 19.

According to the embodiment shown in Figure 4a-4f, the clamp or clip 19 is in the two-part form. Each leg of the clamp or clip 19 is at its upper end provided with a J-shaped hooking means 37, intended to cooperate with a corresponding upwards protruding rib 38 on each side of the bracing 16, locking the upper end of the clamps or clips 19 from lateral movement with respect to the bracing 16.

In order to lock the other end of each part of the clamp or clip 19 to the corner element 15 of the chord, the corresponding surface of the corner element 15 is provided with a recess or a channel intended to receive the fin 33, preventing part of the clamp or clip 19 from rotating about the upper edge 38 of the brace 16 in direction away from the corner element 15. In addition, the fins 31 on the corner element 15 is provided with a bead having a lower locking surface, designed to co- function with a corresponding inner surface on the clamp or clip element 19, or vice versa, thus preventing the clamping or clip elements 19 to move in a direction perpendicularly up and away from its locking position on the corner element 15. Hence, when assembled around the bracing 16, the clip or clamp 19 is prevented from moving up from the corner element 15 and sideways out from the fins 31 on the corner element 15, due to the combined effect from the beads 34/recess 35; and the thin fins 33/protrusion 36, while the bracing 16 is prevented to move upwards from the corner element 15.

In order to prevent relative movement of the bracing 16 with respect to the corner element 15 in axial direction of the corner element 15, both the corner element 15 and the lower protruding ribs 38 on the bracing 16 may be provided with cooperating dents/taps 39, designed to fit into each other, and thus preventing said relative axial movement. Incidentally, it should be appreciated that the dents or recesses on the corner element 15, preferably may be provided at the upper surface of the fins or ribs 31 on the corner element 15.

When installing the bracing 16 on the corner element 15, the bracing 16 is brought into its proper position so that the protrusions 39 on the lower ribs on the bracing 16 engage the recesses 39 in the upper surface of ribs 31 on the corner element 15. The upper end of each clamp or clip element 19 is the hooked on to the upwards projecting protrusions 38 on the bracing 16 and then rotated so that each clamp or clip 19 engages the bead 34 and enters the groove laterally limited by the protrusion 36 at the upper end of the corner element 15, snapping the clamp or clip 19 under the bead and into said grove. Due to the inherent elasticity of this free end of the clamp or clip 19, a locking effect is obtained.

In order to enhance said locking effect the groove formed at the upper, J- formed end of clamp or clip 19 is slightly chamfered.

Figure 5a-5c shows various views and a vertical section through a second embodiment of the clamping or clip means 19 according to the present invention. Figure 5a shows in perspective a vertical section through a clip or clamping means 19 fixing a bracing 16 to a corner element 15; Figure 5b shows a vertical section through the view shown in Figure 5a; and Figure 5c shows the node 17 in an exploded view. According to the embodiment shown in Figures 5a-5c, each clamp or clip 19 is in the form of a single, U-shaped body which is locked to the corner element 15 by means of bolts 40 and nuts 41. For this reason, the lower horizontal fin or rib 33 on the clamping or clip means 19 may optionally be omitted. Apart from these differences, the embodiment shown in Figures 5a-5c corresponds more or less to the embodiment shown in Figures 4a-4f.

Figures 6a-6d shows various views and a vertical section through a node 17 comprising a third embodiment of the clamp or clip means 19; where Figure 6a shown in perspective a typical section through a brace 16 clamped to the corner element 15; Figure 6b shows a vertical section of the assembly shown in Figure 6a; Figure 6c shows an exploded view of the node 17 comprising this third embodiment of the clamping or clip means 19; and Figure 6d shows in perspective an assembled corner element 15 and brace 16.

According to the embodiment shown in Figures 4a-4f, the main difference is the design of the clamping or clip means 19. Compared with the embodiment shown in Figures 4a-4f, the clamping or clip means 19 according to Figures 6a-6d comprises two separate elements forming a U-shaped clamp or clip 19 made up of two separate parts, the two separate parts at their top end being configures in such way that one end is lockable, but rotatably linked to the upper end of the other separate element as a hinge 36. When assembling the two parts, the hinge 36 is formed by adjoining the two ends, inserting one of the J-shaped hooks into the other J-shaped hook also provided with a bead. Further, each J-shaped part is also provided with a rib 45, intended to co-unction with the upwardly extending ribs 38 on the brace profile 16. The two hinged parts are then lowered down onto the profile of the brace 16, so that the ribs 45 on the J-shaped end enter into contact with the upwardly projecting fins 38 on the brace 16. Said contact between the ribs will now provide a rotation point for each of said two parts. When rotating the two legs further, the bead on the fins 31 will enter into contact with corresponding recess on the internal surface of the two parts. Upon completion of the rotation the thin fins 33 are forced into the recess formed on the upper side of the corner element 15. In such manner the brace 16 is locked from moving upwards or sideways with respect to the corner element 15. Further in order to lock the brace 16 from axial movement with respect to the corner element, said node 29 is further provided with the recesses and projections 38 as described above. Figures 7a-7d shows various views and sections through a node 17 based on a fourth embodiment of the clamping or clip means 19; where Figure 7a shows in perspective a assembled node 17; Figure 7b shows in perspective an exploded view of the node 17 shown in Figure 7a; Figure 7c shows in perspective a section through the assembled node 17 shown in Figures 7a and 7b; and Figure 7d shows a vertical section through the node 17.

The only major difference between the embodiment shown in Figures 4a-4f and the embodiment shown in Figures 7a-7d is the design of the lower part of the clamp or clip 19. According to the embodiment in Figure 7-7d the lower part is bolted using bolts and aligned holes or bore in both the fins 31 and the lower ends of each part of the clamp or clip 19. According to the embodiment illustrated in Figures 7a- 7d, use of the recesses and the co-functioning projections are optional. As shown in the Figures one or more bores and bolts may be used.

As shown in the Figures, the corner section 15,15' is formed of an elongated, hollow profile which preferably is made of extruded aluminium. Along two of sides, the corner section 15,15' is provided with two outwards projecting fins 31 spaced apart. The fins 31 extend preferably, but not necessary, along the entire longitudinal direction of the corner sections 15,15'.

As further shown in Figures, the zigzag shaped inclined brace 16 is attached to the fins 31 of the corner sections 15,15' by means of a clip or a clamp or clip 19 according to the present invention. The clamp or clip 19 is given several different shape. As shown in Figures 4a-4e an 7a-7d, the clamp or clip 19 is formed of two separate bodies; as shown in Figures 5a-5c the clamp or clip 19 may have a more or less U-shaped form, while as shown in Figures 6a-6d, the clamp or clip 19 may be made of two separate parts, hinged together at one extreme point.

The inner surface of the clamp or clip 19 is given a shape which corresponds to the external surface of the inclined brace 16. The clamp or clip 19 according to Figures 5a-5c is configured in such way that it is suited for being snapped on to the outwards projecting arms or fins 31 of the corner section 15,15'. In general, the two arms on the clip or clamp 19 have a length which corresponds to the height of the profile of the braces 16 plus an additional sufficient length for enabling the ends of the U-shaped arms to extend past the recesses arranged below the beads 34 at the foot of the upwards projecting fins 31. For this purpose the end of each of the two arms of the U-shaped clip or clamp 19 may be provided with inwards projecting lips 22. The lips 22 are configured to cooperate with the recesses at the foot of the fins, so that the clamp or clip 19 optionally may be snapped on for locking of the braces 16. The arms of the clip or clamp or clip 19 may for this purpose have a certain inherent elasticity, thereby securing that the outer end of each arm of the clip or clamp 19 and the lips may slide past the thickened outer end of the fins 31 and slip into the recess 20, locking the brace 16 to the corner section. In order to ease the snapping, the outer end surfaces of the fins 31 on the corner element 15 may be chamfered.

As further shown in Figures, also the adjoining sides of the corner section 15,15' are formed with a corresponding profile as described above for locking the horizontal braces of the truss girder 11 to the corner section.

According to the invention, a corner section 15, 15' or chord 13,14 may for example be made in length of 15 meters and may be joined by means of joining plates, which will be described in further details below. According to the embodiment shown in Figures, the corner section 15,15' may be provided with attachment means 32 for attachment for example of information carrying signs. Since the corner section 15,15' is extruded, both the fins 31 and the attachment means 32 extend along the entire length of the profile.

It should also be appreciated that also the inclined bracing 16 may be extruded in straight lengths having a uniform cross sectional area, and the bent for formation of the required zigzag shape. As shown in the Figure the profile is further provided with an opening 35 extending through the entire profile. The inclined bracing profile may for example be provided with a straight length of 7 metres. After the bending, and dependent upon the sideways extension, the end product of the inclined bracing may have a length of 5 metres.

It should also be appreciated that the ends of the clamps or clips 19 an the inner surface of each fin 31 may be formed and configured in such manner that the ends of the arms of clamps or clips 19 may be inserted into a space between the two fins 31 and then locked from moving out of said space, optionally also using bolts or nails (not shown) for preventing relative movement. The connection between the clip or the clamp 19 may be improved by gluing adequate surfaces.

Figure 8 shows schematically an alternative embodiment of the present invention, provided with straight braces 16. According to the embodiment shown, the braces 16 comprises straight bars with a skewed end forming an angle α with the corresponding chord 13,14.. The truss girder 10 shown in the Figure 9 comprises an upper chord 13 or corner element and a lower chord 14 or corner element. Further a number of separate braces 16 extend in an inclined manner between said upper and lower chord 13,14., the braces 16 being formed as straight elements having for example a cross sectional shape corresponding to the brace 16 shown in Figure 4e. The braces 16 are fixed to the corresponding chord 13,14 by means of locking clamps or clips 19, the shape and configuration of which will described in further details below. It should also be noted that the chords or corner elements 13,15 have the same as shown for example in Figure 4d. Figure 9 shows schematically in enlarged scale a view of a node 17 comprising a lower chord 14 and the lower end of two straight braces 16, indicating also the configuration and shape of the clips or clamps 19 and the recesses and/or projections; in the braces 16, the lower chord 15 and correspondingly on the lips or clamp 19. Figure 10 shows schematically a vertical section through the node 17, also indicating that the clips 17 are in the form of flat plates. As shown in Figure 10, both the cross sectional shape of the chord 14 and the brace correspond to the shapes indicated for example in Figure 4d. Further, as indicated in the Figure the clips or clamps 19 are in the form of more or less flat plates, having a general shape corresponding more or less to the shape one leg of the clamp 19 shown in Figure 5b. As shown, a clip 19 is arranged on each side the exterior side of a brace 17, the clip 17 at its lower end being provided with a locking shape preventing the clip, and the brace 17 from moving up from the chord 14 when fixed to the chord 14 by means of the clip 17 and locking bolts (not show). The locking shape may be in the form of inwards projecting lips 22 at the lower end of a clip 17 and corresponding outwards projecting beads 34 on the upwards projecting fins 31 on the chords 14 as further described in general terms above. Figure 11 shows schematically, in an exploded view parts of a chord 14 and the lower end of a brace 16, together with a clip 19 according to the present invention. As shown the upwards projecting fins 31 on the cord 14 is provided with recesses 39 more or less corresponding to the recesses 39 shown for example in Figure 4a-4f. Further, the lower end of the brace 16 is provided with corresponding projections 50, configured to fit into the recesses 39 in the fins 31 , thereby preventing lateral movement of the brace 16 along the chord 14 when assembled with said clips 19. as further shown, the brace 16 is provided with outwards projecting fins 38. Compared to the embodiments disclosed in Figures 1 -7, the orientation of said fins 38 are rotated 90 degrees, i.e. extending laterally with respect to the longitudinal direction of the brace 16. At the lower (and upper) end of the brace 17, recesses 51 are provided in each fin 38, i.e. in all four fins 39. The fins 31 on the chord may further be provided with holes 52 in the region of the recesses 39. Correspondingly, the wall of the brace 16 may be provided with a hole 52 a distance above the lower end of the brace 16.

As shown in the Figure 11 , the clip 19 has a skewed lower end 53, the angle of which corresponding to the corresponding skewed end of the brace 16. Further, the clip is along both edges provided with recesses/projections 54, intended to co- function with there projections/recesses 51 on the fins 38 at the lower end of brace 16, thereby also locking brace to move relative to the clips 19 in axial direction. The clip is also provided with holes for co-functioning with the holes 52 in the brace 16 and the fins 31 on the chord.

Figure 12 shows the node 17 in an enlarged scale, showing the chord 14, the two braces 16 and the clips or clamps 19 in an assembled position. As indicated in the Figure the clips 19 are joined with the lower end of the braces in a finger type joint. In the Figure the projections or recesses 39 in the fins 31 and at the lower, contacting ends of the braces 16 are not shown, such means can best be seen in Figure 9 and 11. As further indicated in the Figure, the lower surface of the clips 19 intended to face the outer surface of the fins 31 are provided with a recess for housing the bead 34, thus forming a bead 22 facing the space below the bead 34 of the fin 31 , thereby contributing to the locking effect preventing the clips 19 and hence the braces 16 from moving up and away from the chord 14, when assembled and clamped by means of bolts and nuts.

Due to the shape of the clips 19 and the correspond shaping of the lower end of the braces on both sides, such solution is not dependent upon the shear capacity of bolts, the shear capacity required to secure a shear resistant joint mainly being provided by the finger joint type of locking, thereby using the inherent shear capacity of the materials in both the clips 19 and lower end of each brace 19.

Hence, in assembled position, the brace 16 is prevented from moving both in axial direction along the chord and in transverse direction with respect to the chord. According to the solution shown in the Figures, separate clips 19 are used for fixing and locking the braces 16 to the chord 14, such clips 19 being applied on both side of each brace 16. It should be appreciated, however that each of said two clips 19 on one side of the node 17 may be substituted by a plate (not shown) covering the entire node 17 area. Such plate will on the lower surface facing the external side of the fin 31 be provided with a recess for housing the bead 34 and/or projection 22 for projecting into the space below the bead 34 in order to prevent the brace 17 to be moved up from the chord 14 when in assembled state. For such solution, the bead 34 must also be provided with a number of recesses along such part intended to be covered by such single plate. Accordingly, there are provided holes or openings in the plate corresponding to the protrusions on said bead 34 on the fins 31 , and on the lower (and upper) end of the projecting fins 38. In addition the plates are provided with borings or holes corresponding to the corresponding holes 52 in the brace 16 and in the fins 31 of the chord 14.

Due to the shape of the plate and the correspond shaping of the lower end of the braces 16 on both sides and the beads 34 on the fins 31 , such solution is not dependent upon the shear capacity of bolts, the shear capacity required to secure a shear resistant joint mainly being provided by the protrusions and the corresponding holes in the plate, thereby using the inherent shear capacity of the materials in both the clips 19 and lower end of each brace 19. For manufacturing and assembling a truss girder according to the present invention, the following method may be applied: Firstly the various profiles, i.e. the corner profiles 15,15', the profiles intended to be the basis for the clips or clamps 19, the profiles intended to form the joining plates, and also the profiles forming the inclined brace 16, are extruded. The profile for the clips or clamps 19 and the joining plates are cut into shorter lengths, adjusted to the intended purpose, while the profiles intended to form the braces 16 are bent to the required wave or zigzag shape.

If the truss girder is intended to have a quadrangular cross sectional shape, the upper chord and the lower chord are firstly manufactured separately, the upper chord and the lower chord each comprising two parallel corner sections 15, 15' with an intermediate bracing. A chord is formed by bringing a brace profile into correct position in relation to a corner section profile 15,15', whereupon the clips or clamps 19 are positioned around the intended area on the brace, pressed on to the fins projecting outwards from the corner section 15,15' and snapped on to these. This operation is performed for each contact or node area between the brace 16 and the corner section. When both the upper and lower chord in this way is assembled as separate units, said two different units are assembled by bringing a further brace profile in position between said two chords on each side and fixed to the free fin profile in a corresponding manner as described above.

In use a completed, assembled truss girder is exposed to forces which tend to pull the corner profiles away from the inclined braces. In addition to the hooks and possible tight fit between the various parts and/or surface deformation and adhesion, it may be an additional need of securing that not all joints are positioned in the same cross section. In order to secure a proper attachment between the braces and the corner section, the clip or clamps 19 may in addition therefore be fixed to the fins, for example by means of welding, pressing, point deformations, gluing, riveting, for example by point pressing, or other known ways to secure proper adhesion between two surfaces.

In order to secure as high structurally integrity as possible in the joints between to adjoining profiles, the corner sections may for example be given different length, so that the joints are sideways displaced with respect to each other.

Even though the assembled truss girder shown has a square or rectangular cross sectional shape, it should be appreciated that the cross sectional shape may have a trapezoidal, triangular or polygonal shape. The only essential modification will in such case be the design of the corner profile used for tying the braces together.

Even if the invention is described in respect to large truss girders used for manufacturing large traffic gantries, it should be appreciated that the invention also may be used in respect to other functions. Such other functions may for example be girders used in building construction or industry, as elements forming part of scaffolding, or similar types of areas obvious for a person skilled in the art.

Further, it should be appreciated that according to such solution it will be possible to construct box girders of different cross sectional shape, such as a triangular, square, rectangular or polygonal cross sectional shape.

Claims

C l a i m s

1. Truss girder (10), for example intended to form a transom in a traffic gantry, where the truss girder (10) is formed with triangular, quadrangular or polygonal shaped cross sectional area, produced of a material suitable for extrusion, and comprising at least an upper chord (13) and a lower chord (14) interconnected by means of inclined braces (16), the chords (13,14) being fabricated separately and thereupon fixed together along their corner edges by means of said braces (16) and having corner elements (15) provided with parallel, outwards projecting fins or projections (31 ) in spaced relation, extending preferably along the entire length of said corner elements (15), and that the inclined brace (16) is extruded, given a shape which is complementary the shape of the space between said fins or projections (31 ), and that the inclined brace (16) and said chords (13,14) being fixed together by means of clamping or clip means (19) locking the inclined brace (16) on to said fins or projections (31 ) of the chord (13,14), c h a r a c t e r i z e d in that the fins (31 ) of the chord (13, 14), at portions intended to be connected to the corresponding part of the brace (16), are provided with recesses (39) or projections on the fins or extensions, projecting down into or up from the fins (31 ), while the braces (16) at contact points (17) are provided with projections extending out from the braces (39), or recesses formed in the bracing respectively, said recesses or projections (39) on the fins (31 ) of the chord (13,14) and fins or recesses of the bracing (16) being configured to co-function forming a locking effect against movement of the bracing (16) in axial direction with respect to the chord (13,14).

2. Truss girder (10) according to claim 1 , wherein the brace (39) is in the form of straight units with skewed end surface(s), said recesses and/or the projections of the braces being arranged in the skewed end surface(s).

3. Truss girder (10) according to claim 2, wherein the brace is provided with one or more outwards projecting fin(s) arranged along the edges, intended to lie in the same plane as the fins on the corner elements, said fins on the brace also being provided with recesses or projections, at least at each end of said brace.

4. Truss girder (10) according to claim 2 or 3, where the respective clip(s) for securing the brace(s) to the adjacent corner is provided with recesses configured to co-function with the corresponding projections or recesses on said edges of each brace.

5. Truss girder (10) according to one of the claims 1 -4, wherein said clip(s), brace(s), and the said fin(s) on the corner element is provided with bore(s), configured to receive a locking means, such as bolt and nut, for locking brace(s) further to the corner element.

6. Truss girder (10) according to one of the claims 1-5, wherein the fins or projections (31 ) on corner element (15,15') of the chord (13,14), at their foot on the main body (15,15') of the chord (13,14) also are provided with one or more recesses intended to cooperate with corresponding outwards projecting fins or ribs (33) on the free ends of the clamping or clip means (19), preventing movement of the braces (16) in direction laterally outwards from the chord (13,14).

7. Truss girder (10) according to one of the claims 1 -6, wherein the clamping or clip means (19) at an end intended to be supported by the corner element (15,15') of the chord (13,14) is provided with an foot (33) extending laterally out from the clamping clip means (19), while the corner element (15,15') is provided with a corresponding recess provided with an end stopper on the protrusion (36), said recess being configured to receive said fin or rib (33), preventing the clamping or clip means (19) to swing sideways out from the corner element (15,15') when in installed and locked position.

8. Truss girder (10) according to one of the claims 1 -7, wherein one or more locking bolt (40,41 ) extending trough aligned holes through both the fins (31 ) or projections and the corresponding parts of the bracing (16) is used to prevent relative movement between the corner element (15,15') and the bracing (16) at a node (17).

9. Truss girder (10) according to claim 8, where said inner surface and said space between pairs of fins (31 ) or projections, and the corresponding shape of the profile cross section of the brace (16), are provided with recesses or the like, in order to prevent relative rotational movement of the braces (16) both laterally and outwards from the corner element (15,15').

10. Truss girder (10) according to one of the claims 1 -9, wherein each clamping or clip means (19) comprises two separated elements attached to each side of the bracing profile (16).

11. Truss girder (10) according to one of the claims 1-10, where said clamps or clips (19) are formed of two separate elements which are hinged together at one end and designed for locking to the corner element (15,15') at the opposite end, using bolts or the like.

12. Method for fabrication of a truss girder (10) according to one of the claims 1 - 11 , comprising at least an upper chord (13) and a lower chord (14) interconnected by means of inclined braces (16) and with a distance between the corner elements (15,15') of the truss girder (10), the units forming the truss girder (10), such as the chords (13,14) and bracing (16), are fabricated separately and then assembled, the inclined brace (16), which is in the form of an continuous, elongated corrugation or zigzag shaped element is brought in correct position with respect to a chord (13,14) and wherein one side of the corrugated or zigzag shaped element (16) being attached to said chord (13,14) at a plurality of node positions (17) along the chord (13,14) and the inclined brace (16), the inclined brace (16) being attached to the chord (13,14) at such positions by means of suitable clamping or clip means (19) for clamping and/or bolting the inclined brace (16) to the chord (13,14) at said nodes (17), c h a r a c t e r i z e d i n that nodes (17) of the bracing (16) is brought into correct position with the corresponding sections of the corner element (15,15'), whereupon the projections (39) extending outwards from the profile of the bracing (16), alternatively the recesses (39) on the bracing (16), is brought into interacting contact with the corresponding recesses (39), alternatively the extensions (39) on the fins (31 ) of the corner element 15,15'), and then locked together by means of a clamping or clip means (19) locking the bracing (16) to the corner element (15,15'), so that any relative movement between the bracing (16) and the corner element(s) (15,15') is prevented.

13. Method according to claim 12, wherein said connection(s) between the inclined brace (16) and the corner element (15,15') in addition is improved by means of locking methods, such as riveting, bolting and/or by means of gluing, welding rolling with or without inwards projecting point deformation, surface deformation or the like.