EP1200678A1

EP1200678A1 - Crash barrier for highway or the like comprising wooden fibre-reinforced rails

Info

Publication number: EP1200678A1
Application number: EP00958595A
Authority: EP
Inventors: Jacques De Maussion; Jean-Luc Sandoz
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-07-22
Filing date: 2000-07-21
Publication date: 2002-05-02
Also published as: NO20020312L; WO2001007718A1; MXPA02000775A; US6733002B1; NO20020312D0; TR200200602T2; JP2003505622A; AR028844A1; AU7006700A; FR2796662B1; CA2379812A1; FR2796662A1; TNSN00162A1

Abstract

The invention concerns a safety barrier for highways or the like, comprising rails in abutted assembly and fixed on posts spaced apart and driven into the ground. The invention is characterised in that at least one rail (10) of the barrier is made of wood and comprises synthetic fibres (12) fixed on at least a rear part of its section, extending over substantially its entire length. The invention is useful for road equipment.

Description

"Road safety barrier or the like comprising wooden beams reinforced with fibers."

The invention relates to a safety barrier intended to equip a road or any other lane of traffic to protect the vehicles which circulate there against the risk of a possible dangerous exit of road.

More specifically, the invention relates to a safety barrier of the type which includes posts driven into the ground and spaced from each other, and wooden beams joined end to end to each other and fixed to the posts they interconnect, each stringer having a longitudinal axis, an outer front face facing the road and an outer rear face facing the posts, and being reinforced substantially over its entire length by synthetic fibers forming at least one first web which s extends parallel to the longitudinal axis. More generally, the conventionally used safety barriers consist of a plurality of healds joined end to end to form a continuous and substantially horizontal element, these healds being fixed by bolts on posts which are spaced apart and driven into the ground.

These slides most often include metal rails, wooden rails or wooden rails reinforced with a metal element.

In the event of a vehicle impact on the slide, the role of the slide is first to absorb the dynamic energy of the vehicle to prevent it from bouncing on the road and being violently returned to the road or still very damaged.

This energy is mainly absorbed by the posts which deform when they are made of metal or which break when they are made of wood.

Furthermore, the substantially horizontal continuous element formed by the heddles must not break completely, even at the point of impact of the vehicle on the slide. This element tends as the posts deform, while remaining continuous, to allow the vehicle which has come off the road to be gradually brought back there, preventing it from falling into the unstabilized lateral zone of the road or in a ravine.

The slides with wooden beams have many qualities but also some defects that should be corrected.

Indeed, wood is a material characterized by a fragile elastic behavior in tension and plastic elastic in compression. The impact of the vehicle on the slide results in a pulling force in the beams, on the side opposite to the impact.

Under these conditions of stress, the traction zone bursts and can, by propagation of cracks, cross the beam (s) concerned and break them completely. Even pine wood, whose plasticization phase is relatively important, does not guarantee the continuity of the slide in the event of an impact.

This is why the guides comprising wooden beams are rather used, traditionally, on roads where the shocks are weak, for example on mountain roads or on portions of road on which the vehicles can circulate only at speed very small.

It has already been envisaged to reinforce the wooden beams by metal fittings integrated at the rear of the beams, that is to say on the side of the posts. Reference may in particular be made to document FR-2 717 196.

Subject to having sufficient and well-designed reinforcement, such slides can provide the same safety conditions as metal slides, while being more easily integrated into the environment. They therefore bring full satisfaction.

However, they have the disadvantage of being relatively heavy due to the presence of the elements of metal reinforcement, which poses problems during transport and installation of the slides. The cost of these slides is also relatively high.

The German utility model DE-G-94 05 557.2 describes a wooden slide which uses, as smooth, wooden logs longitudinally sawn into two halves, between which is arranged a simple flat metallic iron, the elementary form of 'Such reinforcement limiting the additional weight and cost. However, not only does such a slide remain relatively heavy and costly, but the flat metallic iron, under the conditions of use described, has a resistance that is too low to fulfill any function other than simply maintaining the continuity of the beam in the event of choc.

We also know, from patent document EP 0 924 346, a wooden slide of the first type mentioned above, that is to say in which the beams are reinforced with synthetic fibers. With the difference of material, the slide described in this document has the same structure as the slide described in the German utility model DE-G-94 05 557.2, namely that it uses, as beams, logs of wood longitudinally sawn into two halves, between which is laid a sheet of synthetic reinforcing fibers.

If the slide described in patent document EP 0 924 346 obviously benefits, compared to the slide of the German utility model DE-G-94 05 557.2, from a reduction in weight and cost inherent in the change of material produced , on the other hand the sheet of fibers can only provide this slide with a resistance even less than that which the flat metallic iron brings to the slide of the German utility model DE-G-94 05 557.2. In this context, the object of the present invention is, in particular, to propose a relatively light and inexpensive slide, using wooden beams, and whose beams nevertheless have increased resistance, effectively allowing any vehicle that has left it to be brought back onto the road.

To this end, the slide of the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that at least some of the fibers of the first web of each stringer are bonded to the stringer and are arranged at a distance from the longitudinal axis, closer to the rear external face than to the front external face of this heald.

In other words, instead of being arranged in the neutral fiber of the heald as in patent document EP 0 924 346, that is to say exactly between the zone in which the heald, in the event of impact , undergoes traction and the area in which it undergoes compression, the fibers arranged in accordance with the invention on the one hand offer tensile forces a resistance which is added to that of wood, and on the other hand ensure cohesion wood fibers over a significant depth, which has the additional effect of increasing the elasticity of the beam as a whole.

In a possible embodiment of the invention, the first web of fibers of each stringer extends in a plane parallel to the longitudinal axis and separates the stringer into a front part facing the road and a rear part facing the posts, the front part being thicker than the rear part.

The synthetic fibers used are preferably fibers with high mechanical performance and in particular have a tensile strength at least twice that of wood.

The synthetic fibers fixed to the heddle by gluing are advantageously glued by means of a resin. Furthermore, at least some of the fibers reinforcing the heald are advantageously oriented along the axis of the heald, which corresponds to the direction of the wood fiber. In order to stabilize the cross section of the heddle dimensionally, some of these fibers are advantageously oriented in at least one direction making a non-zero angle with the axis of the heddle. Preferably, the grammage of the fibers is greater at the level of the areas for fixing the heald on the posts than on the rest of the heald, so as to limit the risks of tearing in these fastening areas where significant efforts are concentrated locally, mainly around the means of fixing the heald on a post.

The fibers can also be fixed at least partially on the upper part of the beam, exposed to the weather, so as to increase the durability of the wood. In addition, a notch is advantageously made at the lower part of the heald, to release the stresses due to the shrinkage of the wood which naturally occurs in the wood when it dries and thus to avoid the formation of cracks on the periphery of the heald .

In a preferred embodiment, at least a portion of the fibers is placed over the entire outer surface of the heddle.

In particular, these fibers can form a tubular knit, threaded onto the wooden heald and then fixed thereon.

This characteristic further increases the interest of the invention.

Indeed, as the wood of the slides is normally subjected to bad weather and to the attacks of destructive organisms, such as fungi or insects, it must undergo a treatment, in particular with metallic salts, to increase its durability.

However, when the slides are dismantled, the wooden beams must be recycled to limit the pollution due to metal salts with which the wood is impregnated and which are very toxic. The costs involved in recycling treated wood are very high since they are around three times higher than the price of natural wood itself.

Thus, the fact that the only known treatments, intended to increase the durability of the wood, require the use of polluting substances, constitutes another very significant drawback.

This drawback which exists moreover not only for the woods intended for the manufacture of slides, but also for all the woods used outside, such as those being used for the construction of barriers or even of children's games, arranged for example in squares, can thus be eliminated by enclosing the wooden beam in a sleeve of synthetic fibers, the fibers of which adjacent to the rear face of the beam considerably increase the resistance of the latter.

Finally, fibers can be placed, without being fixed, between the wood of the heald and fibers glued to the heald. The synthetic fibers used can in particular be glass, carbon or Kevlar® fibers or a mixture of these fibers.

The invention will be better understood and other objects, advantages and characteristics thereof will appear more clearly on reading the description which follows and which is given with reference to the appended drawings in which: FIG. 1 is a perspective view a classic safety barrier made of wooden rails with a metal reinforcement; - Figure 2 is a sectional view along II-II of Figure 1;

- Figure 3 is a plan view of the rear side of a heddle of a slide according to the invention;

- Figure 4 is a sectional view along IV-IV of Figure 3, which shows a section of the heddle;

- Figure 5 is a view similar to Figure 4 illustrating a second alternative embodiment of a smooth of a slide according to the invention, with a third alternative embodiment illustrated in dotted lines; and - Figure 6 is a view similar to Figure 4 illustrating a fourth alternative embodiment of a wooden rail of a slide according to the invention.

We first refer to Figures 1 and 2 which illustrate a section of a conventional slide which is composed of metal posts 1, driven into the ground S. Each of them carries a spacer 2 made of wood, here of cylindrical shape . It is on these spacers 2 that wooden beams 3 and 4 are fixed which are joined end to end by any appropriate means and in particular fishplates 5.

Each stringer is fixed, at each of its ends, to a spacer 2 by any appropriate means and in particular a bolt 7.

FIGS. 1 and 2 also show that each wooden heald, of cylindrical section, is notched with two longitudinal slots which receive two wings 8a and 8b of a metal profile 8.

This profile is conventionally used to reinforce the wooden beam to prevent it from bursting when an impact of a vehicle against the slide, and guarantee the continuity of the slide.

Reference is now made to FIGS. 3 and 4 which illustrate a wooden heald used in a slide according to the invention. In this exemplary embodiment, the heddle 10 is of semi-cylindrical section. Figure 3 illustrates this smooth view from the rear according to arrow III shown in Figure 1, or on the side of the metal posts 1 or the ravine which runs along the road bordered by the slide. FIG. 3 shows that, on the rear flat face 11 of the heald 10, synthetic fibers 12 are fixed which extend over substantially the entire length of the heald 10.

These fibers 12 extend here over part of the rear face 11, but they could also be fixed over the entire rear face.

It will also be noted that the synthetic fibers 12 are, in this example, unidirectional and are oriented in the direction of the wood fibers. Furthermore, at the two end zones 14 and 15 of the heddle 10, other synthetic fibers 13 are provided. In this example, they are oriented in two directions making an angle of 45 ° with the direction of the fibers 12.

These intertwined fibers 13 are therefore provided at the two end regions of the heald, which correspond to the areas for fixing the heald 10 on metal posts 1. The fibers 12 respectively 13 are fixed over the entire length of the heald, respectively each end zone by bonding obtained in particular by a resin.

In an exemplary embodiment, the fibers 12 consist of three layers of a sheet of unidirectional glass fibers, the grammage of which can vary between 290 g / m ² and 600 g / m ² . The glass fiber sheets sold under the name Vetrotex® with the references UC 290 and UC 600 are suitable for this application. Furthermore, the synthetic fibers 13 may for example consist of two additional layers of a sheet of bidirectional glass fibers, in particular sold under the name Vetrotex®, with the reference RT 600. By way of example, the grammage of the fibers of glass may be between 600 and 1000 g / m ² at the assembly zones and between 300 and 600 g / m ² on the rest of the stringer, it being understood that the grammage is adapted to the technical requirements which take into account the speed and the type of vehicles likely to come into contact with the slide.

The various layers of fibers can in particular be glued, layer by layer, with an epoxy adhesive, in particular West System adhesive, sold by the company Wessex Resins & Adhesive Limited.

Other methods of fixing the fibers could be envisaged, it being understood that bonding makes it possible to diffuse the forces over a large surface, avoiding any concentration of stresses. The fibers used are not necessarily glass fibers but, in general, synthetic fibers having high mechanical performance, that is to say mechanical performance much higher than that of wood and at least twice that of wood. This is particularly the case with carbon fibers or Kevlar®.

The presence of such synthetic fibers, at the rear of the heald opposite to a possible impact (see for example Figure 4), makes it possible to modify the behavior of the wooden heald. As explained above, the impact of a vehicle against the slide at the level of the arm 10 generates a dynamic bending which decomposes itself on the section of the arm, by a traction zone on the side opposite to the impact and an compression on the shock side.

The presence of the fibers does not modify the behavior of the wood on the impact side, plastic behavior in compression, the wood absorbing the energy generated by this shock. It is even possible, in certain extreme cases, that the wood bursts under the effect of the shock.

However, the traction generated by the impact on the rear side of the heald causes stretching of the synthetic fibers which, given their mechanical characteristics, do not break. Thus, it is these synthetic fibers which ensure the continuity of the slide in the event of an impact, a priori as a metal section would do, such as section 8 illustrated in FIGS. 1 and 2.

In reality, the slide according to the invention comprising beams reinforced with fibers behaves better, in the event of impact, than a slide with beams reinforced by mechanical profiles because it turns out to be less rigid than a slide with beams reinforced with metal and therefore can absorb more energy. Consequently, the car hitting a slide according to the invention absorbs less energy and suffers less damage.

Thus, to ensure the continuity of the slide in the event of an impact, the fibers must be at least partly oriented along the axis of the heddle or even according to the direction of the wood fiber. The fibers 13 provided at the end zones 14 and 15 of the heddle 10 prevent local tearing of the fibers 12.

Indeed, these end parts of the heald 10 are, in practice, areas of assembly of the heald 10 on posts 1. This assembly is generally carried out by bolts such as that referenced 7 in FIG. 2. These bolts locally concentrate significant forces both in the direction of the wood fibers and in the perpendicular direction. Without transverse reinforcement, these bolts may locally burst the wooden beam, by cracking between a bolt and the end of the beam. This is why the fibers 13 are advantageously oriented at 45 ° relative to the direction of the wood fiber.

Apart from the end portions of the heddle 10, one can also provide other fibers than the fibers 12 which extend in the direction of the wood fibers.

In particular, the unidirectional fibers can be replaced by a bidirectional fabric which then makes it possible to dimensionally stabilize the section of the heddle. These deformations can in particular be due to the drying of the wood and they are more frequently encountered in the beams whose diameter is at least 25 cm.

Reference is now made more precisely to FIG. 4 which illustrates a first alternative embodiment of a wooden heald of a safety barrier according to the invention.

In this variant, the heddle 20 comprises a wooden log of cylindrical section.

This log is previously sawn into two parts 21 and 22 of different sizes, sawing being carried out along a plane parallel to the fibers of the wood, perpendicular to the section of the log.

In the front portion 22 of larger dimension, a notch or groove 23 is made which also extends in the direction of the wood fibers.

As illustrated in FIG. 4, another notch or groove 24 can also be made in the extension of the notch 23, inside the front part 22. This notch 24 also extends in the direction wood fibers but has a height less than that of the notch 23.

In the notch or groove 24, fibers are arranged which are not glued to the wood. These fibers can in particular be in the form of one or more layers of superimposed fibers, these fibers preferably being oriented in the direction of the wood fibers.

In the groove 23, fibers are placed, at least some of which are oriented in the direction of the wood fibers or else along the longitudinal axis of the heddle 20.

As indicated above, these fibers can in particular be in the form of several layers of unidirectional fibers which are bonded successively, by means of a resin.

Once the fibers 25, respectively 26 are placed in the grooves 24, respectively 23, the part

21 of the previously sawed heald is placed on the other part 22 of the heald 20 so as to cover the fibers placed in the notches.

This fixing is carried out by any suitable means and in particular by nails or screws 27.

Thus, the bonded fibers 26 fulfill the same function as the fibers 12 illustrated in FIG. 3. The heddle 20 is arranged so that the part 21 and the fibers 24 and 26 are arranged on the side of the metal posts of the slide and so on the opposite side of the road.

In the event of a vehicle impact on the rail 20, the fibers 26 modify the behavior of the wood on the side opposite to the impact, ensuring the continuity of the slide.

Furthermore, the fibers 24 which are not fixed guarantee better continuity of the wooden beam in the event of a vehicle impact, especially in very specific cases where the bonded synthetic fibers could be broken.

However, the invention is not limited to this embodiment and only glued synthetic fibers 26 could be provided in the groove 23. FIG. 5 illustrates a second alternative embodiment of a heddle 30 for a slide according to the invention.

This heddle 30 is made from a log of wood of cylindrical section.

It comprises, over its entire outer surface, synthetic fibers 31 which are at least partially fixed. These fibers are therefore arranged over the entire outer part of the section of the heddle. As explained above, this fixing is preferably carried out by gluing for better diffusion of the forces.

In practice, these fibers 31 can be in the form of a tubular knit which is threaded on the heddle 30 and then fixed thereon.

When the fibers 31 are fixed to the entire outer surface of the heddle 30, this second variant has the advantage of avoiding any prior treatment of the wood to increase its durability. Furthermore, this embodiment strengthens the cohesion of the wood and prevents, in the event of a vehicle impact against the heald 30, wood debris can be ejected at the point of impact, this debris can be dangerous. for vehicle passengers. In a third alternative embodiment illustrated in dotted lines in FIG. 5, the heddle 30 can be previously cut into two parts of different dimensions 32 and 33, along a longitudinal plane of the heald 30 or even a plane parallel to the wood fiber . Synthetic fibers 34 can then be bonded to the portion 33 of larger dimensions, as explained above with reference to FIGS. 3 to 5.

The part 32 of the smaller beam is then fixed to the part 33 by any suitable means, and in particular nails or screws 35.

Once these operations have been completed, the outer surface of the heald 30 can be covered with synthetic fibers 31 which are preferably bonded to the entire outer surface of the heald. The presence of the fibers 34 makes it possible to further reinforce the stringer 30.

Figure 6 illustrates a fourth alternative embodiment of a wooden beam 40 suitable for a slide according to the invention.

This heald 40 is produced from a log of wood of cylindrical section.

This heddle 40 is previously sawn into two parts 41 and 42 of different dimensions, along a longitudinal plane parallel to the fibers of the wood.

Synthetic fibers 43 are deposited and fixed on the internal rear face of the front part 42, that is to say on the rear side opposite the possible impact of a vehicle. The rear part 41 is then fixed to the first part 42 by any suitable means 44.

In this alternative embodiment, synthetic fibers 45 are also placed on the upper part of the heddle 40, intended to be mainly subjected to bad weather. These synthetic fibers 45 are also fixed by gluing to the upper part of the heddle 40.

Furthermore, conventionally, a notch 46 may be provided in the lower part of the heddle 40.

This notch frees up the internal drying stresses which occur naturally when the wood dries.

Thus, the synthetic fibers 43 make it possible, like the fibers 12 or 26 described above, to modify the behavior of the wood in the event of a vehicle impact on the rail 40, while ensuring the continuity of the slide.

Furthermore, the fibers 45 bonded to the upper part of the heald 40 make it possible to protect from bad weather or from any damage to destructive organisms, the upper part of the heald 40 which is the most exposed.

Thus, these fibers 45 bonded to the upper face of the heald make it possible to increase the durability of the wood constituting the heald 40 and this, without requiring conventional treatment with metal salts, these fibers not necessarily having high mechanical performance.

Thus, the two alternative embodiments illustrated in FIGS. 5 and 6 make it possible, thanks to the fibers 31, respectively 45, to increase the durability of the wood without treatment with polluting products.

In the case where synthetic fibers are provided on the exterior surface of a wooden heald, a surface treatment, such as a suitable paint, can be provided to avoid any degradation of the fibers and of the resin by light. This paint can then constitute a support for a fluorescent material, which is particularly suitable for crash barriers, for example to reinforce the signaling of the route of the road.

In all the exemplary embodiments which have just been described, reference has been made to sheets of fibers bonded to wood or to another sheet using a resin. The invention is of course not limited to this embodiment. One could also provide for bonding to a part of the section of the heddle fiber already impregnated with a resin and being in the form of a preconstituted strip, the ply and the strip being grouped under the term "veil".

Furthermore, the grammage of the synthetic fibers placed on a wooden rail of a slide according to the invention is chosen according to the envisaged applications and in particular of the shocks that the slide must be able to withstand while remaining continuous. It also depends on the nature of the synthetic fibers chosen.

Finally, the section of a wooden rail of a slide according to the invention can be arbitrary. However, it is preferable that the boom has a rounded section on the side of the road, such as a cylindrical or semi-cylindrical section. Indeed, sections with edges, such as a square or rectangular section, cause a concentration of stresses at these edges in case shock, which has harmful consequences for the vehicle.

Tests have been carried out to highlight the reinforcement function of the synthetic fibers placed at the back of a wooden beam.

The tests were carried out with a wooden beam, formed of a Douglas-fir log having a cylindrical section with a diameter of 18 cm.

A notch or groove has been formed in the stringer, over its entire length. Then, three layers of glass fibers were successively glued in this groove and over the entire length of the stringer by West epoxy resin.

System.

The glass fiber layers used are of the RT 600 type from Vetrotex® which are bidirectional with a grammage of 600 g / m ² .

The total length of the arm is 4 m, the arm being placed on two supports distant from 3.71 m.

The tests consisted in applying a load varying between 5,000 and 35,000 N in the middle of such a beam reinforced with fibers and in measuring the displacement.

Similar tests were carried out with wooden beams made of a Douglas-fir log, also having a diameter of 18 cm and a length of 4 m, this log, on the other hand, containing no bonded fiber.

These tests have shown that an unreinforced wooden beam breaks under a force of 20,000 N.

On the contrary, a heald reinforced with glass fibers has a plastic character, that is to say it deforms without breaking for this same force and, for larger forces, deforms in a very important way, but without break, the invention therefore having the effect of overcoming the fragility of natural wood. The reference signs inserted after the technical characteristics appearing in the claims have the sole purpose of facilitating the understanding of the latter and should not limit their scope.

Claims

claims

1. Safety barrier intended to equip a road or any other traffic lane, this barrier comprising posts (1, 2) driven into the ground and spaced from one another, and wooden beams (3, 4) joined together tipped to each other and fixed to the posts which they connect to each other, each stringer having a longitudinal axis (36), an external front face facing the road and a rear external face facing the posts, and being substantially reinforced on its entire length by synthetic fibers (12, 13) forming at least one first web which extends parallel to the longitudinal axis (36), characterized in that at least some of the fibers of the first web of each stringer are bonded to the heald (3, 4) and are arranged at a distance from the longitudinal axis (36), closer to the rear external face than to the front external face of this heald.

2. Safety barrier according to claim 1, characterized in that the first web of fibers of each stringer extends in a plane parallel to the longitudinal axis

(36) and separates the beam into a front part (22, 33, 42) facing the road and a rear part (21, 32, 41) facing the posts, the front part being 'thicker than the rear part.

3. Slide according to any one of claims 1 and 2, characterized in that the synthetic fibers are fibers with high mechanical performance, and in particular have a tensile strength at least twice that of wood.

4. Slide according to any one of the preceding claims, characterized in that the fibers bonded to the heddle are bonded by means of a resin.

5. Slide according to any one of claims 1 to 3, characterized in that some at fewer fibers (12, 25, 26, 31, 43) are oriented along the axis of the heddle (10, 20, 30).

6. Slide according to any one of the preceding claims, characterized in that at least some of the fibers (13) are oriented in at least one direction making a non-zero angle with the axis of the heddle (10).

7. Slide according to any one of claims 1 to 6, characterized in that the grammage of the fibers is greater at the level of the fixing zones (14, 15) of the stringer on the posts than on the rest of the stringer (10 ).

8. Slide according to any one of claims 1 to 7, characterized in that the fibers (31, 45) are arranged at least on an upper external face of the heald, exposed to the weather.

9. Slide according to any one of claims 1 to 8, characterized in that a notch (46) is made in the lower part of the heddle (40), to release the stresses due to cracks.

10. Slide according to any one of claims 1 to 9, characterized in that at least part of the fibers (31) form an outer layer placed over the entire outer surface of the heddle (30).

11. Slide according to claim 10, characterized in that the fibers placed on the entire outer surface of the heald form a tubular knit, threaded on the heald (30) and fixed thereon.

12. Slide according to any one of claims 1 to 11, characterized in that it comprises fibers (25) arranged, without being fixed, between the wood of the heald (20) and fibers (26) glued to the smooth.

13. Slide according to one of claims 1 to 12 characterized in that the synthetic fibers are glass, carbon or Kevlar® fibers or a mixture of such fibers.