EP0361227A2 - Prestressed concrete railway sleeper - Google Patents

Abstract

In a prestressed concrete railway sleeper whose sleeper body (1) consists of two supporting bodies (2, 2') carrying the rail fastenings and a centre part (3) of smaller cross-section, the prestressing elements (4), such as, for example, steel bars, wires or strands, starting from a point where they are united in a vertical and/or horizontal plane in the sleeper centre, are run radially and rectilinearly to the sleeper ends (5, 5'), where they are anchored in uniform distribution over the cross-sectional areas of the sleeper ends. By the uniting of the prestressing elements (4) in the sleeper centre, the use of a sleeper body having a narrow, high centre web and wide sleeper ends also becomes possible for prestressed concrete sleepers, in which sleeper body only slight alternating bending moments arise in the centre part or a unidirectionally positive pattern of the bending moments can be permitted over the entire length of the sleeper. <IMAGE>

Description

The invention relates to a railway sleeper made of prestressed concrete with a monolithic sleeper body consisting of two support bodies supporting the fastening parts for the rails and a middle part connecting them and with a reinforcement made of tensioning elements, and a method for their production.

Railway sleepers with such a sleeper body are known in large numbers, especially when executed in reinforced concrete. The advantage of such a shape of the sleeper body lies primarily in the fact that the supporting bearing forces of the ballast bed are concentrated on the areas around the axes of the rails. This results in a reduction in the bending moments, particularly in the slimmer middle part of the threshold, which leads to less reinforcement requirements and thus to greater economy. Disadvantages are the more complex manufacture of the reinforcement due to this shape and the risk of cracks forming in the sleeper body under vibrating loads, which greatly reduced the practical importance of such sleepers.

The threshold body of prestressed concrete sleepers usually has a prismatic shape. This results in higher bending moments compared to a sleeper body with a slim middle section; however, these are accepted in favor of a simple linear guidance of the tensioning elements. A pronounced reduction in cross-section in the middle part of the sleeper body is not possible in any case with prestressed concrete sleepers, since the position of the individual tensioning elements is determined from the outset by the necessary uniform distribution of their end anchorages over the cross-sectional areas of the sleeper ends.

The invention has for its object to provide a way for a railway sleeper made of prestressed concrete in order to be able to reduce the cross section of the sleeper body in the middle part of the sleeper compared to the support bodies, while maintaining the uniform distribution of the end anchorages of the tensioning elements, so as to achieve a more favorable distribution of the bending moments to come.

According to the invention, this object is achieved in a railway sleeper made of prestressed concrete in that the central part has a smaller cross-section than the support body and the tensioning elements, starting from a junction in a vertical and / or horizontal plane in the middle of the sleeper, radiating essentially straight to the sleeper ends and the ends of the tensioning elements being distributed substantially uniformly over the cross-sectional areas of the sleeper ends.

The tensioning elements can run in a straight line between their end regions and intersect in the middle of the threshold.

In each case two clamping elements running at the same angle, but inclined in opposite directions to the threshold axis, in mutually parallel planes can form a pair of clamping elements. In this case, at least two pairs of clamping elements can be arranged side by side or one above the other, or one pair of clamping elements can be arranged between a further pair of clamping elements.

Two clamping elements can be connected to each other at one end by a curved part like a loop.

An embodiment is particularly useful for the production of sleepers in a long fitted bed in each case two tensioning elements arranged on the sleeper ends at the same distance from a cross-sectional axis are brought together in the middle of the sleeper and held by means of a connecting part.

By merging the tensioning elements in the middle of the sleeper body, be it in a cross shape or in the form of close parallel guidance, the use of a sleeper body with a high, narrow central web and wide sleeper ends is also possible for prestressed concrete sleepers, with only slight alternating bending moments occurring in the middle section, yes even a unidirectionally positive course of the bending moments over the entire threshold length can be made possible. Nevertheless, due to the beam-like expansion of the tensioning elements starting from the middle of the sleeper, even with comparatively wide sleeper ends, a uniform distribution of the end anchorages over the respective cross-sectional area of the sleeper ends can be achieved. At the same time, a staggered arrangement of the end anchorages allows the tensioning elements to be positioned very eccentrically in the cross-section of the sleeper.

Correspondingly, when the tensioning elements are brought together in a horizontal plane, a sleeper body can also be constructed, the middle part of which has a flat rectangular cross section and is therefore largely elastic.

Overall, these measures lead to a considerable reduction in the amount of prestressing steel required for a prestressed concrete sleeper. Thus, the amount of prestressing steel customary in known sleepers decreases from approx. 5 kg per sleeper according to the invention by up to 40% to approx. 3 kg per sleeper.

The invention also relates to a method for producing prestressed concrete sleepers in a long way Clamping bed, along which stretching elements that can be clamped against fixed abutments extend, in the area of which successive stations are provided for the continuous production of the prestressed concrete sleepers in formwork forms, in which the clamping elements are initially laid out in parallel and stretched, then at each production station in the respective formwork form merged in pairs in the middle of the threshold and held by means of connecting parts.

• Fig. 1 in schematischer Darstellung den Grundriß einer Spannbetonschwelle mit geraden, einander kreuzenden Spannelementen,
• Fig. 2 eine schematische Seitenansicht der Spannbetonschwelle gemäß Fig. 1,
• Fig. 3 eine Ansicht eines Schwellenendes entlang der Linie III-III in Fig. 1,
• Fig. 4 einen Querschnitt in Schwellenmitte entlang der Linie IV-IV in Fig. 1,
• Fig. 5 eine der Fig. 3 entsprechende Ansicht eines Schwellenendes mit anderer Führung der Spannelemente,
• Fig. 6 in schematischer Darstellung den Grundriß einer Spannbetonschwelle mit einander kreuzenden schlaufenförmigen Spannelementen,
• Fig. 7 eine schematische Seitenansicht der Spannbetonschwelle nach Fig. 6,
• Fig. 8 eine Ansicht des Schwellenendes entlang der Linie VIII-VIII in Fig. 6,
• Fig. 9 einen Querschnitt in Schwellenmitte entlang der Linie IX-IX in Fig. 6,
• Fig. 10 eine schematische Seitenansicht einer Spannbetonschwelle mit flachrechteckigem Mittelteil und schlaufenförmigen Spannelementen,
• Fig. 11 eine Ansicht des Schwellenendes entlang der Linie XI-XI in Fig. 10,
• Fig. 12 einen Querschnitt in Schwellenmitte entlang der Linie XII-XII in Fig. 10,
• Fig. 13 in schematischer Darstellung den Grundriß einer Spannbetonschwelle mit mittig zusammengeführten Spannelementen,
• Fig. 14 eine Ansicht eines Schwellenendes entlang der Linie XIV-XIV in Fig. 13 und
• Fig. 15 einen Querschnitt in Schwellenmitte entlang der Linie XV-XV in Fig. 13.

The invention is explained in more detail below with the aid of a few exemplary embodiments shown in the drawing. It shows

• 1 is a schematic representation of the floor plan of a prestressed concrete sleeper with straight, crossing clamping elements,
• 2 shows a schematic side view of the prestressed concrete sleeper according to FIG. 1,
• 3 is a view of a threshold end along the line III-III in Fig. 1,
• 4 shows a cross section in the middle of the threshold along the line IV-IV in FIG. 1,
• 5 a view corresponding to FIG. 3 of a sleeper end with a different guidance of the tensioning elements,
• 6 shows a schematic representation of the floor plan of a prestressed concrete sleeper with crossing loop-shaped tensioning elements,
• 7 is a schematic side view of the prestressed concrete sleeper according to FIG. 6,
• 8 is a view of the threshold end along the line VIII-VIII in Fig. 6,
• 9 shows a cross section in the middle of the sleeper along the line IX-IX in FIG. 6,
• 10 is a schematic side view of a prestressed concrete sleeper with a flat rectangular central part and loop-shaped tensioning elements,
• 11 is a view of the threshold end taken along the line XI-XI in Fig. 10,
• 12 shows a cross section in the middle of the threshold along the line XII-XII in FIG. 10,
• 13 is a schematic representation of the floor plan of a prestressed concrete sleeper with clamping elements brought together in the middle,
• Fig. 14 is a view of a threshold end along the line XIV-XIV in Fig. 13 and
• 15 shows a cross section in the middle of the sleeper along the line XV-XV in FIG. 13.

1 to 4 each show a schematic representation of a first embodiment for the design of the sleeper body and the guidance of the tensioning elements. The sleeper body 1 consists of two comparatively wide lateral support bodies 2, 2 ', which carry the - rail fastening, not shown for the sake of clarity, and one Middle part 3 with a comparatively narrow, high cross-section. The sleeper body 1 is reinforced with four straight clamping elements 4, which are anchored at the sleeper ends 5, 5 'by means of end anchors 6.

The tensioning elements 1 consist of steel rods, wires or strands and are guided so that they lie one above the other in a vertical plane V-V in the middle of the threshold (FIG. 4) and spread out radially towards the threshold ends 5, 5 '. Your end anchorages 6 are distributed as evenly as possible over the surface of the preferably trapezoidal cross section at the threshold ends 5, 5 '(Fig. 3). This arrangement allows the formation of a very slim middle part while maintaining sufficient concrete coverage.

The geometry of the radiating clamping elements 4, which can be seen in FIG. 1, does not permit an arrangement symmetrical to the vertical center line of the cross section V-V. If the usual conditions for prestressed concrete sleepers are met, that the prestressing must not result in any horizontal bending moments and no torsional moments, because these would lead to undesirable deformations and twists of the sleeper, so there are only a few options for distributing the end anchorages 6 at the sleeper ends 5, the most important of which are shown in FIGS. 3 and 5.

2 and 3 show the combination of two clamping elements 4a, 4b and 4c, 4d to form a pair of clamping elements. The tensioning elements 4a, 4b and 4c, 4d of each pair of tensioning elements each have an inclination of the same size but in opposite directions with respect to the longitudinal axis of the threshold LL (FIG. 1) and run in horizontal planes parallel to one another (FIGS. 2 and 3). The inclinations to one another and the distances between the clamping elements 4a, 4b and 4c, 4d, which form a pair, are so chosen that no torsional moments occur. The end anchors 6 are arranged on both threshold ends 5, 5 'in the same way.

In an illustration corresponding to FIG. 3, it is also indicated in FIG. 5 how the clamping elements 4c and 4d forming a pair can also be arranged between the clamping elements 4a and 4b forming the other pair in order to avoid the generation of torsional moments.

On the basis of these two basic embodiments, each with four individual straight tensioning elements 4, depending on the need and load, multiplication of the tensioning elements 4 can provide further other options for the distribution of the end anchors 6. It is also possible to insert individual clamping elements lying in the vertical plane V-V and running parallel to the longitudinal axis L-L.

In order to reduce the number of end anchors, it is known to use hairpin-shaped reinforcement elements in prestressed concrete sleepers, which can be imagined that two straight tension elements are connected at one end by a curved part to form an assembly unit. 6 to 9, a prestressed concrete sleeper is shown, the sleeper body 11 in turn has two broad support bodies 12, 12 'connected by a slim central part 13 and is reinforced with tension elements 14 connected in this way to hairpins. 5, the arrangement is such that two tensioning elements 14a and 14b or 14c and 14d form a pair, but here are connected at one end by a loop 17. The anchor loops 17 should be at right angles to one another in order to reduce the splitting tensile forces arising from the force deflection (FIG. 8). 6 and 7 can be seen the position of the loop-like deflection points 17 at the threshold end 15 '. 8 and 9 show the course of the tensioning elements 14 in the sleeper cross-section over the length of the sleeper and the arrangement of the anchors at the sleeper end 15.

10 to 12, an embodiment for the reinforcement in prestressed concrete sleepers is shown, the sleeper body 21 between the support bodies 22, 22 'has a central part 23 with a low wide cross section in the middle of the sleeper; such thresholds are known as "elastic middle part" thresholds. As can easily be seen from the illustrations, the guidance of the tensioning elements 24 results from the fact that the arrangement described in connection with the embodiment according to FIGS. 6 to 9 is rotated by 90 degrees against the longitudinal axis of the threshold. 10 shows in longitudinal section the position of two pairs of tensioning elements 24a, 24b and 24c, 24d, which, starting from the middle of the sleeper (section XII-XII), radiate upwards and downwards. As shown above all in FIG. 12, all tensioning elements 24 lie in a horizontal plane H-H in the middle of the threshold.

11 shows the view of the threshold end 25. The basic arrangement of the pairs of tensioning elements 24a, 24b and 24c, 24d corresponds to that in FIG. 8 after rotation by 90 degrees about the longitudinal axis of the threshold. The tensioning elements 24c, 24d in turn lie between the tensioning elements 24a, 24b of the other pair. Of course, although clamping elements 24 with curved deflection points 27 are shown, the use of individual straight clamping elements 24 with end anchorages 6 at both ends is also possible here.

Instead of an arrangement of the tensioning elements, which is crossed in the middle of the threshold, as described, it is also too narrow to bring together two tensioning elements Parallel guidance possible in the middle of the threshold. Such an embodiment, which is particularly suitable for the production of prestressed concrete sleepers in the long prestressed bed with an immediate bond, is shown in FIGS. 13 to 15.

The schematic plan view of a sleeper body 31 according to FIG. 13 with wide support bodies 32, 32 'and a flat middle part 33 again shows straight clamping elements 34 which are brought together in pairs in the middle of the sleeper (section XV-XV) towards the longitudinal axis LL and are held by a connecting part 38 . 15, which shows this section, a connecting part 38, here designed as a clamp, is necessary in each position of the tensioning elements 34. The design of the connecting part 38 as a clamp has the advantage that it can be placed on the side of the tensioning elements 34 in the course of the tensioning elements 34, so that they do not have to be threaded through a ring. At the threshold ends 35, 35 '(Fig. 14) a symmetrical to the cross-sectional axis arrangement of the end anchors is provided. Since in the production of prestressed concrete sleepers in the long prestressed bed the end anchoring takes place by means of an adhesive bond without any special anchor parts, the end anchoring indicated in FIG. 14 can only be regarded as wire ends.

When producing prestressed concrete sleepers in a long prestressed bed, the prestressing elements along the prestressing path are usually first laid out in parallel with one another and tensioned against fixed abutments. At the threshold ends 35, 35 ', the clamping elements 34 are guided in a conventional manner in slot-like recesses in the end faces of the formwork.

In a second step, starting at the fixed abutment of the tensioning track, the tensioning elements 34 are then paired in the middle of the threshold in the area of the first formwork Merged using a suitable device and held by means of the connecting parts 38 made of metal or plastic. The tensioning force that increases due to the merging of the tensioning elements can be automatically reduced to the intended setpoint by a controller on the tensioning press of the movable tensioning track abutment.

Subsequently, the connecting parts 38 are attached to the following formwork in a corresponding manner, whereupon the resulting tension force is reduced again. This process is repeated continuously until the last form of form on the movable tensioning abutment. All other operations then follow in the usual way.

Claims (8)

1. Railway sleeper made of prestressed concrete with a monolithic sleeper body (1, 11, 21, 31) from two supporting parts for the rails supporting the rails (2, 2 ', 12, 12', 22, 22 ', 32, 32') and one these connecting middle part (3, 13, 23, 33) and with a reinforcement of tensioning elements (4, 14, 24, 34), such as steel bars, wires or strands, the middle part (3, 13, 23, 33) one has a smaller cross section than the support body (2, 2 ', 12, 12', 22, 22 ', 32, 32') and the clamping elements (4, 14, 24, 34) from a merger in a vertical and / or horizontal plane starting in the middle of the threshold, radiating substantially straight to the threshold ends (5, 5 ', 15, 15', 25, 25 ', 35, 35') and the ends of the tensioning elements (4, 14, 24, 34) being substantially uniform are distributed over the cross-sectional areas of the threshold ends (5, 5 ', 15, 15', 25, 25 ', 35, 35'). 2. Prestressed concrete sleeper according to claim 1, characterized in that the tensioning elements (4, 14, 24) run rectilinearly between their end regions and intersect in the middle of the sleeper. 3. Prestressed concrete sleeper according to claim 2, characterized in that two tensioning elements (e.g. 4a and 4b, 4c and 4d) running in mutually parallel planes form a pair of tensioning elements in each case at the same angle but inclined in the opposite direction to the sleeper axis. 4. prestressed concrete sleeper according to claim 3, characterized in that at least two pairs of clamping elements (eg 4a, 4b and 4c, 4d) are arranged side by side or one above the other. 5. Prestressed concrete sleeper according to claim 3, characterized in that in each case one pair of tensioning elements (e.g. 4c, 4d) is arranged between a further pair of tensioning elements (e.g. 4a, 4b). 6. Prestressed concrete sleeper according to one of claims 1 to 5, characterized in that two tensioning elements (e.g. 14a and 14b, 14c and 14d) are connected to one another at one end by a curved part (17) in a loop-like manner. 7. prestressed concrete sleeper according to claim 1, characterized in that in each case two on the sleeper ends (35) arranged at the same distance from a cross-sectional axis tensioning elements (34) are brought together in the middle of the sleeper and are held by means of a connecting part (38). 8. A method for producing prestressed concrete sleepers according to claim 7 in a long fitted bed, along which stretchable clamping elements extend in several rows against fixed abutments, in the area of which successive stations are provided for the continuous manufacture of the prestressed concrete sleepers in formwork forms, characterized in that the Tensioning elements (34) are initially designed to run parallel and tensioned, then brought together in pairs in the respective formwork form in the middle of the sleeper at each production station and held by means of connecting parts (38).

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