EP1354841A1 - Triangulation of a lattice beam, in particular of a jib element for a tower crane - Google Patents

Abstract

The triangulation of a trellis beam for a jib (13) comprises, for a beam lateral face defined by a upper (2) and lower (3) ribs, compression bars (14) each connecting the upper to the lower rib. Oblique traction bars (17) each connect the top (15) of a compression bar to the lower rib in a point (18) located at a pitch (P) in front of the base of the compression bar. Other oblique traction bars (19) each connect the top of a compression bar to the lower rib in a point (20) located at two pitches in front of the base (16) of this bar.

Description

The present invention relates to a beam triangulation in lattice, in particular a cantilever beam. More particularly, this invention relates to the triangulation of a lattice boom element, or a lattice counter-boom element, a tower crane.

In a generally known manner, a tower crane boom, the along which an arrow cart usually moves, is constituted by a succession of arrow elements, aligned and assembled to each other. others so as to constitute an arrow having the desired length. Each boom element is a structure of the kind lattice girder, section triangular, rectangular or trapezoidal, which includes chords defining two to two plane faces. In each of these planar faces, the two chords are interconnected by elongated pieces of the kind bars, which together form what is called a "triangulation". This guy of structure is also applied to the counter-arrows of tower cranes, which support a counterbalance balancing the boom and possibly the load raised.

This kind of lattice girder has the particularity, as far as its side faces, to have a top chord always tensioned, and a lower chord always compressed, when the beam is at work.

The most common triangulation configuration currently, for tower crane boom elements, is that illustrated in Figure 1 of the attached schematic drawing which represents, in perspective, a section of arrow element. This is a section arrow element triangular, its single upper chord is indicated in 2, while its two lower chords are indicated in 3.

• des barres 4 et 5 perpendiculaires aux membrures 2 et 3, et reliant chacune la membrure supérieure 2 à l'une des membrures inférieures 3 ;
• d'autres barres 6 et 7 s'étendant en oblique, chaque barre oblique dite "diagonale" reliant le sommet de l'une des barres précédentes 4 ou 5 à la base de la suivante de ces barres.

The triangulation comprises, repeating in the longitudinal direction according to a pitch P, and in each lateral face of the considered boom element:

• bars 4 and 5 perpendicular to the frames 2 and 3, and each connecting the upper chord 2 to one of the lower chords 3;
• other bars 6 and 7 extending obliquely, each slash called "diagonal" connecting the top of one of the previous bars 4 or 5 at the base of the next of these bars.

The horizontal underside of the boom element has a different structure, with crossbars 8, 9, 10 and diagonal bars alternates 11, 12.

As an example of such a known triangulation for element of arrow, reference is made to patent application FR 2773550 A in the name of Applicant, or its equivalent, EP 0928769 A.

• pour les barres 4 et 5 : efforts de compression ;
• pour les autres barres 6 et 7 : efforts de traction.

Referring always to Figure 1, if one considers the forces in the lateral triangulation bars at two consecutive P steps, these efforts are as follows, regardless of the value of the load lifted by the crane, or the position of the load:

• for bars 4 and 5: compressive forces;
• for the other bars 6 and 7: tensile forces.

As a result, the lengths of bars 4 and 5 must be the smaller possible, to avoid buckling due to compression. The lengths of the other bars 6 and 7 may be larger.

The main disadvantage of this type of triangulation is that it is not not optimal in dimensioning, and that in particular the structure corresponding remains of relatively high weight.

The present invention aims at eliminating these disadvantages, therefore at optimize the construction of a truss element, more particularly of an element of arrow or counter-arrow for tower crane, in reducing the number of component parts of the element, thus reducing the weight of this element, and also reducing its resistant side surface at wind, thus reducing its manufacturing cost and the cost of operating the crane.

• des barres de compression, sensiblement perpendiculaires aux membrures, et reliant chacune la membrure supérieure à la membrure inférieure, ces barres de compression se succédant selon un intervalle égal au double du pas P ;
• des barres obliques de traction, de plus petite longueur, reliant chacune le sommet d'une barre de compression à la membrure inférieure, en un point situé à un pas P en avant de la base de cette barre de compression ;
• d'autres barres obliques de traction, de plus grande longueur, reliant chacune le sommet d'une barre de compression à la membrure inférieure, en un point situé à deux pas P en avant de la base de cette barre de compression, donc à la base de la barre de compression suivante.

For this purpose, the subject of the invention is a triangulation of a lattice girder, in particular of a lattice boom element, or of a lattice counter-jib element, of a tower crane, this triangulation comprising, for a side face of said beam or said lattice member defined by an upper chord and a lower chord, and divided longitudinally by a predefined pitch P:

• compression rods, substantially perpendicular to the ribs, and each connecting the upper chord to the lower chord, these compression rods succeeding one another by an interval equal to twice the pitch P;
• sloping tension bars, of smaller length, each connecting the top of a compression bar to the lower chord, at a point at a pitch P in front of the base of this compression bar;
• other traction slashes, of greater length, each connecting the top of a compression bar to the lower chord, at a point situated at two steps P in front of the base of this compression bar, therefore at the base of the next compression bar.

The triangulation object of the invention is thus characterized by the combination of more spaced compression bars, so less numerous, and of "diagonals" of two kinds, some shorter and others longer. It should also be noted that this structure is characterized by particular assembly nodes, at the upper chord, each of these nodes being, globally, the convergence point of a bar compression, a "short" slash and a "long" slash.

The compression bars ensure the recovery of main efforts. "Long" oblique pull rods also have a recovery function of main efforts. As for the "short" oblique pull rods, these have particular functions of recovery of the vertical forces due to the passage of the carriage and counter-buckling of the lower chord.

• les barres de compression comportent une extrémité supérieure aplatie et découpée, avec une arête supérieure rectiligne et parallèle à l'axe longitudinal de la membrure supérieure, et soudée sur cette membrure ;
• les barres de traction obliques de plus grande longueur comportent une extrémité supérieure aplatie et découpée, avec une arête supérieure rectiligne et parallèle à l'axe longitudinal de la membrure supérieure, et soudée sur cette membrure, l'extrémité supérieure aplatie de ces barres possédant aussi une arête postérieure sensiblement verticale venant contre une arête correspondante antérieure de l'extrémité supérieure aplatie d'une barre de compression, et ces deux arêtes adjacentes étant soudées l'une à l'autre ;
• les barres de traction obliques de plus petite longueur comportent une extrémité supérieure aplatie et découpée, venant chevaucher les extrémités supérieures aplaties adjacentes d'une barre de compression et d'une barre de traction oblique de plus grande longueur, le périmètre de l'extrémité supérieure aplatie de chaque barre de traction oblique de plus petite longueur étant soudé sur les extrémités supérieures aplaties des autres barres, qu'elle chevauche.

All of these bars, whether compression rods or "short" and "long" oblique tensile bars, are preferably made of circular or oval section tubes, with flattened and cut ends for the production of assembly nodes. In particular, for the realization of the upper assembly nodes which constitute points of convergence of the three types of triangulation bars, it is advantageously provided that:

• the compression bars comprise a flattened and cut top end with a rectilinear upper edge parallel to the longitudinal axis of the upper chord and welded to this chord;
• the longer oblique tensile bars have a flattened and cut top end with a rectilinear upper edge parallel to the longitudinal axis of the upper chord and welded to this chord, the flattened upper end of these bars also having a substantially vertical posterior ridge against a corresponding anterior edge of the flattened upper end of a compression bar, and these two adjacent edges being welded to each other;
• the smaller length oblique tensile bars have a flattened and cut top end overlapping the flattened upper ends of a compression bar and a longer oblique tensile bar, the perimeter of the upper end flattened of each oblique tensile bar of smaller length being welded to the flattened upper ends of the other bars, which it overlaps.

According to a particular embodiment of this triangulation, the respective neutral fibers of the compression bars, and the bars of oblique traction of greater length, are concurrent with each other, in points lying in a horizontal plane containing the neutral fiber of the upper chord.

In the case of a beam or section boom element triangular, the respective neutral fibers of the compression bars, and oblique traction bars of greater length, belonging to both side faces, are all concurrent to each other at points located in a vertical plane containing the neutral fiber of the upper chord.

Still in the case of a triangular section arrow element, the respective neutral fibers of the smaller oblique tensile bars length, belonging to the two lateral faces, are also concurrent between them at points in the vertical plane containing the neutral fiber of the upper chord.

• une réduction du nombre de pièces constitutives pour la fabrication de l'élément de flèche ;
• un gain de poids de cet élément de flèche, entraínant lui-même une réduction du lest de la contre-flèche et de la structure même de la contre-flèche ;
• une diminution de surface latérale résistante au vent pour l'élément de flèche, entraínant elle-même une réduction de la surface compensatrice du vent pour la contre-flèche.

Overall, this gives a lateral boom element triangulation for a tower crane that provides:

• a reduction in the number of component parts for the manufacture of the boom element;
• a weight gain of the boom element, itself causing a reduction in the weight of the counter-boom and the structure of the same against-arrow;
• a wind-resistant lateral surface reduction for the boom element, itself causing a reduction of the compensating surface of the wind for the counter-boom.

All of these advantages result in a significant economic gain, both in the manufacture of the elements boom and crane, than in the operation of this crane, more especially during its assembly on building sites.

Figure 1 (déjà mentionnée) est une vue en perspective d'un tronçon d'élément de flèche, avec triangulation selon l'état de la technique ;

Figure 2 est une vue de côté de l'élément de flèche avec cette triangulation de l'état de la technique ;

Figure 3 est une vue de côté d'un élément de flèche avec triangulation selon l'invention ;

Figure 4 est une vue en perspective d'un tronçon de l'élément de flèche avec triangulation selon l'invention ;

Figure 5 est une vue en perspective, à plus grande échelle, montrant le détail d'un noeud d'assemblage supérieur de la triangulation selon l'invention ;

Figure 6 est une vue de côté de ce noeud d'assemblage ;

Figure 7 est une vue en coupe transversale de la partie supérieure de l'élément de flèche avec triangulation selon l'invention.

The invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing showing, by way of nonlimiting example, an embodiment of this triangulation, applied to an element of boom for crane to tower:

Figure 1 (already mentioned) is a perspective view of a section of arrow element, with triangulation according to the state of the art;

Figure 2 is a side view of the boom member with this triangulation of the state of the art;

Figure 3 is a side view of an arrow element with triangulation according to the invention;

Figure 4 is a perspective view of a section of the arrow element with triangulation according to the invention;

Figure 5 is a perspective view, on a larger scale, showing the detail of an upper assembly node of the triangulation according to the invention;

Figure 6 is a side view of this assembly node;

Figure 7 is a cross-sectional view of the upper part of the arrow element with triangulation according to the invention.

Figure 1 recalls the principle of triangulation known, on a section of an arrow element of a tower crane. AT complementary title, Figure 2 shows the arrow element complete, designated by 13, realized with this triangulation repeats according to step P, along the entire length of the arrow element 13. Being a side view, this figure 2 shows more particularly the lateral triangulation of the boom element 13, with its substantially vertical bars and slashes.

For comparison, Figure 3 shows an element of arrow 13 made, with regard to its two lateral faces, with a triangulation according to the invention, also represented in perspective (for a stretch of this arrow element) in the figure 4.

Being a section 13 boom element triangular, we consider here, more particularly, the triangulation one or the other of the two lateral faces, defined by the upper chord 2 and one of the two chords lower 3.

The lateral triangulation includes bars of compression, substantially vertical, which each connect a point 15 of the upper chord at a point 16 of the chord lower 3. The compression bars 14 succeed one another regular interval 2P, equal to twice the predefined pitch P.

Lateral triangulation also includes 17, oblique traction, which each connect the top 15 of a bar of compression 14 at a point 18 of the lower chord 3, the point 18 lying at a step P in front of base 16 of this same compression bar 14.

Finally, the triangulation includes other bars of traction, oblique, and of greater length than the preceding. Each drawbar 19 connects the top 15 of a compression bar 14 at a point 20 of the lower chord 3 being located two paces ahead of base 16 of this same compression bar 14, so at the base of the bar of next compression 14.

It follows from the previous description that the summit 15 of each compression bar 14 constitutes a knot assembly, where converge (for a lateral face of the boom element 13) a compression bar 14, a bar of oblique traction 17 of smaller length and a drawbar oblique 19 of greater length, and where these three bars 14, 17, 19 are also connected, directly or indirectly, to the frame superior 2.

With regard to the horizontal lower face of the boom element 13, it remains in the traditional manner, with sleepers 8, 9, 10 regularly spaced according to pitch P, and with alternating diagonal bars 11, 12.

Referring to the following figures 5, 6 and 7, we will describe now, in the case of a preferred embodiment, details of the lateral triangulation, particularly concerning the upper assembly node 15.

The different kinds of bars 14, 17 and 19 are all consisting of circular section tubes, the ends of which are flattened, and cut to a suitable contour, to realize the assembly nodes. In particular, the extremities upper compression bars 14, pull rods obliques 17 of smaller length, and drawbars oblique 19 of greater length, are flattened ends and cutouts designated respectively by 21, 22 and 23, adapted for the realization of the upper assembly nodes 15.

The flat top end 21 of each bar of compression 14, which has a generally rectangular shape or in parallelogram, in particular has a top edge 24 rectilinear and parallel to the longitudinal axis A of the rib upper 2, here tubular. This edge 24 is welded on the upper chord 2, following a generator of this chord 2.

The flat top end 23 of each bar of oblique traction 19 of greater length has a shape pentagonal, and in particular has a ridge upper rectilinear, and a rear ridge 26 rectilinear. The upper edge 25, parallel to the longitudinal axis A of the upper chord 2, is welded to this chord 2, following a generator of this one, in the extension of the cord of welding of the upper edge 24 of the flattened upper end of the compression bar 14. The posterior ridge 26, substantially vertical, is placed against the anterior ridge 27 of the flattened upper end 21 of the compression bar 14. The two adjacent edges 26 and 27 are welded to each other.

The flat top end 22 of each bar of oblique traction 17 of smaller length, which has a shape general rectangular, is applied externally against flattened upper ends 21 and 23 adjacent to a bar of compression 14 and an oblique tensile bar 19 more long, overlapping both ends flattened 21 and 23. The perimeter 28 of the flattened upper end 22 of the oblique pull rod 17 is welded on the ends flattened 21 and 23 of the other bars 14 and 19.

Finally, with reference to Figures 6 and 7, details additional information is given in respect of fibers neutral of the various bars 14, 17, 19 of the lateral triangulation of the boom element 13.

We first consider, in each lateral face of the boom member 13, the neutral fiber 29 of a bar of compression 14, and the neutral fiber 30 of the oblique pull rod 19 of greater length associated with it. Both fibers 29 and 30 are concurrent between them, at a point 31 located in a horizontal plane P1 which contains the neutral fiber of the upper chord 2, confused here with the longitudinal axis A of this upper chord 2.

Now considering the symmetrical bars belonging respectively to the two lateral faces of the element 13, the respective neutral fibers 29, 30 of the bars of compression 14, and oblique pull rods 19 more great length, are all concurrent among them in points 33 in the vertical plane P2 containing the neutral fiber (A-axis) of the upper chord 2. Similarly, the respective neutral fibers 32 oblique pull rods 17 of smaller length, belonging to the two lateral faces of the boom element 13, are concurrent at points located in the vertical plane P2 containing the neutral fiber (axis A) of the chord superior 2.

It has been shown by calculation that triangulation Lateral, previously described, constitutes a solution advantageous in terms of alleviation, in particular for relatively high-rise boom elements, for example for arrowheads greater than about one metre.

As a consequence of the above, the triangulation lateral object of the invention is particularly applicable to the realization of the boom of a tower crane without masthead, this not excluding its application to tower cranes with masthead with boom carrier function, particularly for cantilevered parts crane arrows with arrow holders.

• en réalisant la triangulation avec des barres de tout type, par exemple des barres tubulaires de section ovale ou rectangulaire, ou des cornières, ou encore des barres plates, ces barres pouvant être de section constante ou de section variable sur leur longueur ;
• en modifiant des détails constructifs, tels que ceux du noeud d'assemblage supérieur ;
• en réalisant des modifications dimensionnelles, par exemple en avançant ou reculant la position du noeud d'assemblage supérieur ;
• en modifiant les positions des points de concours des fibres neutres ;
• en appliquant la même triangulation aux faces latérales d'éléments de flèche de section autre que triangulaire, par exemple de section rectangulaire ou trapézoïdale ;
• en appliquant cette triangulation à des éléments de contre-flèche pour grue à tour, ou encore à d'autres poutres ou éléments de poutre en treillis.

One would not depart from the scope of the invention, as defined in the appended claims:

• by triangulation with bars of any type, for example tubular bars of oval or rectangular section, or angles, or flat bars, these bars may be of constant section or variable section along their length;
• modifying constructive details, such as those of the upper assembly node;
• by making dimensional changes, for example by advancing or retreating the position of the upper assembly node;
• by modifying the positions of the points of competition of the neutral fibers;
• applying the same triangulation to the lateral faces of arrow elements of section other than triangular, for example of rectangular or trapezoidal section;
• applying this triangulation to counter-boom elements for tower cranes, or other beams or truss elements.

Claims (6)

Triangulation of a lattice girder, in particular of a lattice-shaped deflection element (13), or of a lattice counterframe element, of a tower crane, characterized in that it comprises, for a lateral face of said beam or said lattice element (13) defined by an upper chord (2) and a lower chord (3), and divided longitudinally in a predefined pitch (P): compression rods (14), substantially perpendicular to the ribs (2, 3), and each connecting the upper chord (2) to the lower chord (3), these compression rods (14) succeeding one another at an interval (2P) equal to twice the pitch (P); sloping traction slits (17) of smaller length, each connecting the top (15) of a compression bar (14) to the lower chord (3) at a point (18) at one step (P). ) in front of the base of this compression bar (14); other longer sloping tension bars (19), each connecting the top of a compression bar (14) to the lower chord (3), at a point (20) situated at two steps (P) in front of the base (16) of this compression bar (14), thus towards the base of the next compression bar (14). Triangulation according to claim 1, characterized in that the compression rods (14) and the "short" (17) and "long" (19) oblique tensile bars (19) are made of circular or oval section tubes, with flattened and cut ends (21, 22, 23) for producing the assembly nodes (15). Triangulation according to claim 2, characterized in that , for the realization of the upper assembly nodes (15): the compression bars (14) have a flattened and cut upper end (21) with an upper edge (24) straight and parallel to the longitudinal axis (A) of the upper chord (2) and welded to this chord ( 2); the longer oblique tensile bars (19) have a flattened and cut upper end (23) with a straight upper edge (25) parallel to the longitudinal axis (A) of the upper chord (2), and welded to said chord (2), the flattened upper end (23) of said bars (19) also having a substantially vertical rear edge (26) against a corresponding front edge (27) of the flattened upper end (21) a compression bar (14), and these two edges (26, 27) being welded to each other; the oblique pull rods (17) of smaller length have a flattened and cut top end (22) overlapping the flattened upper ends (21, 23) adjacent to a compression bar (14) and a bar an oblique pull (19) of greater length, the perimeter (28) of the flattened upper end (22) of each slash (17) of smaller length being welded to the flattened upper ends (21, 23) of the other bars (14, 19), that she rides. Triangulation according to any one of claims 1 to 3, characterized in that the respective neutral fibers (29, 30) of the compression rods (14), and oblique tensile rods (19) of greater length, are concurrent between they at points (31) situated in a horizontal plane (P1) containing the neutral fiber (A) of the upper chord (2). Triangulation according to claim 4, characterized in that , in the case of a beam or an arrow element (13) of triangular section, the respective neutral fibers (29, 30) of the compression bars (14), and oblique tensile bars (19) of greater length, belonging to the two lateral faces, are all concurrent with each other at points (33) situated in a vertical plane (P2) containing the neutral fiber (A) of the upper chord ( 2). Triangulation according to claim 5, characterized in that the respective neutral fibers (32) of the oblique traction rods (17) of smaller length, belonging to the two lateral faces, are also concurrent at points situated in the vertical plane (P2 ) containing the neutral fiber (A) of the upper chord (2).

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