EP0244495A1 - Joint covering in roadways, in particular in bridge decks - Google Patents

Abstract

A joint covering in roadways, in particular in bridge decks, which is adjacent to the road surface (11) comprises an elastomeric plate (2) which bridges the joints (1) and whose longitudinal edges are in each case fixedly connected to the associated joint edge (6, 7). In order to prevent the plates (2) from curving upwards under the action of horizontal pressure forces D, the plate (2) has on its underside edge notches (10) or cavities (17) or is additionally reinforced in the edge region on its upper side. In order to prevent the elastomeric plate (2) being raised from its base under the action of horizontal tensile forces Z, the plate (2) has on its underside at least one cut notch (13); the cut notch (13) is virtually or completely closed in the non-stressed state of the elastomeric plate, but spreads under the action of horizontal tensile forces Z. <IMAGE>

Description

The invention relates to a joint cover adjacent to the road surface in traffic routes, in particular of bridges, with an elastomeric plate bridging the joint, the longitudinal edges of which are each firmly connected to the associated joint edge, the plate having at least one notch on its underside.

Such a known joint cover (US Pat. No. 3,324,774) has an elastomeric plate consisting of inclined ribs with webs which are bent downwards and are bent between them at a middle height of the ribs. The plate has on its underside border notches adjacent to the longitudinal edges and, because of the oblique ribs, further notches which adjoin the webs mentioned. Both the edge notches and the further notches are designed in the form of grooves which are open at the bottom and which remain open even under the action of horizontal compressive forces while the webs bulge downwards. When the plate is deformed under pressure, there is a tendency to bend downwards because the edge notches deflect the pressure force downwards, so that the plate rests non-positively on the joint edges. The ribs form the effective plate cross-section. The plate is not subject to tensile stress.

In this case, however, the plate would bulge upwards. H. Lift off the surface, because the edge notches then reverse the traction upwards.

Another known joint cover (US Pat. No. 3,316,574) has an elastomeric plate with a closed surface, without notches on its underside, but with cavities for material displacement in the event of compression deformation. Under the influence of horizontal compressive forces, the plate tends to bend downwards, caused by metal plates vulcanized in the middle of the plate near its underside or by cavities in the middle of the plate, which are arranged off-center, namely offset to the top of the plate. The elastomeric plate is not intended to be subjected to tension. As a result of the explained design of the plate cross section, under the action of tensile forces the plate would warp upwards, i.e. the plate would lift off its surface.

Finally, joint covers are known (French patent specification 2 116 665) in which the joint is bridged by an elastomeric folding profile which is firmly connected at the longitudinal edges to the associated joint edge. Such folding profiles, which are notched alternately from above and from below, with the formation of their folding profile, can only withstand limited vertical loads. When they are deformed, the shape change forces of the folding mechanism are in the foreground, with other force mechanisms prevailing compared to the plate-shaped joint covers explained above.

In addition, other types of joint covers are known (DE-GM 6 609 118) in which an elastomeric plate with a closed surface is connected in the middle to a metal strip. The metal strip has edges that are curved upwards, which engage in grooves on the underside of the elastomeric plates and stiffen the plate in the lower region under the action of horizontal compressive forces. This results in a deflection of the plate downward when the pressure is deformed, so that it rests on the base. A strain on train is not intended. In the event of a tensile load on the plate, the metal strip would loosen its engagement in the grooves and would not cause bulging; in no way would there be a tendency for the plate to bend downward, with the result that the underside of the plate rests positively on the base; this observation also applies to all known joint covers explained above. These are also insufficient in the case of tensile deformations, namely are stored without frictional engagement with the base, ie they are subject to constant blows downwards under the influence of traffic loads, with the result that they are subject to rapid wear.

In contrast, the present invention has for its object to achieve a non-positive fit of the elastomeric plate on a base with a joint cover of the type mentioned both when Zugals and compression deformation of the plate. i.e. when both horizontal tensile forces and horizontal compressive forces act on the plate edges, the plate should tend to deflect downwards.

This object is achieved according to the proposal of the invention in that the notch is designed as a cut notch, which is almost or completely closed in the de-energized state of the plate, so that the entire plate cross-section acts in the case of compression deformations, while the cut notch expands in the case of tensile deformations, in which essentially only the plate cross section remaining above the cut notch acts.

The expression cut notch is to be understood to mean such a notch which, when de-energized, allows the surfaces delimiting the notch to lie against one another, similar to a narrow incision in the underside of the plate.

Because the cutting notch is practically closed when the plate is in a de-energized state, the plate cross-section can change depending on the type of stress, similar to a "system of variable structure" known in the art. When deformed, the plate acts like a closed plate without a notch; in the event of tensile deformation, the cut notch opens and only the remaining plate cross-section is effective.

This proposed solution makes it possible to change the conditions when the plate is deformed in such a way that the plate is inevitably subjected to a downward bending stress, so that it always lies snugly and non-positively on its base.

Thus, while essentially the entire cross-section of the plate is effective for the reaction forces in the case of horizontal compressive forces, only the upper partial cross-section of the plate, which extends downward from the surface of the plate, is effective, i.e. the partial cross-section above the cut notch. When the cut notch is spread under the effect of horizontal tensile forces, the plate is subjected to a downward bending stress.

According to the proposal of the invention, the plate has edge notches adjacent to the longitudinal edges and at least one further notch in a known manner. If this additional notch is designed as a cut notch, the effect of the edge notches means that the plate cross-section effective for the reaction to compressive forces, measured from the road surface, extends further downwards than the edge height of the plate connected to the joint edge and vice versa, the plate cross-section effective for the reaction to tensile forces, on the other hand, extends less far downwards.

In the sense of static considerations, the known edge notches are that the center of gravity of the plate center is lower than that at the edge when the joint cover is subjected to pressure, the improvement according to the invention being that the center of gravity of the plate center is higher than that at the edge when there is tensile stress. The decisive factor is the changing position of the center of gravity depending on the type of load, corresponding to the effective cross-section in the center of the board (parallel to the longitudinal direction of the joint).

The edge notches and at least one cut notch ensure that both with horizontal tensile forces and with horizontal compressive forces, a bending moment is always generated in the elastomeric plate, which has the tendency to press the plate downwards. This makes it possible to prevent the plate from bulging under pressure and to lift it off its base under tension. By ensuring that the panel lies flat on the base, the adverse impact effects of vehicles rolling over it are avoided, which gives the joint cover an overall longer service life.

At least in the case of wider joints, the entire or part of the elastomeric plate preferably lies on a rigid, plate-shaped base that bridges the joint. But it can also rest directly on the joint edges without such a base being provided. This option is particularly suitable for narrow gap gaps.

An essential embodiment of the invention is that the cut notch merges into a fillet or into a cavity at its inner end. The slot-shaped opening of the cavity closes during the compression deformation and the overall cross-section of the elastomeric plate acts, the center line of which, depending on the position and shape of the cavity, remains approximately in the cross-sectional center and thus deeper lies as the edge line of gravity displaced upwards by the edge notches, which corresponds to the location of the force application of the horizontal forces. The result is that when the plate is deformed, it bends downwards. During the tensile deformation, the cut notch connected to the cavity opens and only the plate cross section remaining above the cavity acts for the tensile reaction forces, the center of gravity of which still lies above the boundary line of gravity. The result in the case of tensile deformation is therefore also a downward bend.

In compression molding, the cavity and edge notches provide the necessary space for material displacement without significantly increasing the plate thickness. During tensile deformation, the transverse contraction is greatly reduced by the cavity due to the reduced tensile cross section. In addition, since less elastomeric material is deformed in the area between the edge notches and the cavity due to the expansion of the cavity, the plate thickness remains almost unchanged even under tensile load.
In addition, the cavity has the advantage of preventing notch cracks or stress cracks in the area of the plate-inner end of the cut notch. For this purpose, however, a small cavity in the sense of rounding off the end of the cut notch is sufficient, the depth of which, including the cavity, is preferably between a third and a half of the plate thickness.

In order for a downward bending moment to be generated under the influence of tensile forces on the elastomeric plate in the presence of edge notches, it should be noted that the edge notches penetrate less deeply into the plate than the cut notch. This is the only way to ensure that the center of gravity of the remaining upper partial cross section of the plate is higher than the center of gravity in the edge area of the plate.

In the context of the invention, closed hollow chambers at the location of the edge notches are also suitable as technical equivalents for the edge notches. Another possibility consists in stiffening edge notches or hollow chambers in the area of the underside of the plate, instead stiffening the overlying edge area thereof by appropriate inserts.

In the context of further developments of the invention, it is possible to provide the elastomeric plate with a plurality of cut notches, with or without cavities. With wider joints, at least two notches will be arranged. The shape of the cut notches - whether straight, corrugated or serrated - their direction to the plate surface and their arrangement to the cavities can influence the deformation pattern of the plate.

The position of the slot-shaped part of the cut notches with respect to the cavities connected to them can also be off-center.

• Fig. 1 einen vertikalen Querschnitt durch eine Fu­genabdeckung in spannungslosem Zustand der elastomeren Platte,
• Fig. 2 einen Querschnitt gem. Fig. 1 in zusammenge­drücktem Zustand der elastomeren Platte,
• Fig. 3 einen Querschnitt gem. Fig. 1 in gedehtem Zustand der ealstomeren Platte,
• Fig. 4 einen Querschnitt durch eine Fugenabdeckung für eine schmale Fuge und
• Fig. 5 jeweils hälftig zwei Varianten zu Fig. 4.

The invention is explained below with reference to the drawing; show it

• 1 is a vertical cross section through a joint cover in the de-energized state of the elastomeric plate,
• Fig. 2 shows a cross section. 1 in the compressed state of the elastomeric plate,
• Fig. 3 shows a cross section. 1 in the expanded state of the ealstomeric plate,
• Fig. 4 shows a cross section through a joint cover for a narrow joint and
• 5 two halves of two variants of FIG. 4.

1 to 3 each show, in different joint positions, a vertical cross section through a joint cover, the cutting plane running transversely to the longitudinal direction of the joint.
The joint 1 is bridged by an elastomeric plate 2, the material preferably being a highly elastic material with a low tendency to creep, for example chloroprene. The elastomeric plate 2 is vulcanized with its side faces 3 to an edge angle 4. The edge angles 4 are each anchored in the concrete of the associated joint edge 6, 7 by means of bolts, the axes of which are indicated by the lines 5. The road surface 8, for example an asphalt roadway, borders on the side of the edge angle 4 facing away from the joint 1.

On the underside of its longitudinal edges 9, the elastomeric plate 2 each has an edge notch 10. The rounded end of the edge notches 10, which is inside the plate, is at a distance a below the road surface 11. Thus, the edge line of gravity r runs at a medium height at horizontal compressive forces D or tensile forces Z. Distance a (for simplification it is always assumed here that the joint cross-section shown is constant in the longitudinal direction of the joint).

Starting from its underside 12, two cut notches 13 are also provided between the two edge notches 10. To avoid notch cracks, the cut notches 13 each have fillets 14 on their inner end. The cut notches 13 are cut deeper into the elastomeric plate 2 than the edge notches 10. Depending on their depth t, there is still a distance h from the road surface 11 which corresponds to the difference between the plate thickness s and the depth t of the cut notches 14.

The cross section of the elastomeric plate 2, which is effective for the reaction to horizontal compressive forces D, corresponds to its total thickness s, as shown in FIG. 2, since the cut notches 13 close under pressure. Accordingly, the center of gravity d runs at pressure reaction forces DR in the middle height of the plate thickness s. The effective cross section for the reaction of the elastomeric plate 2 to tensile forces Z corresponds to. Fig. 3 the distance h, since there is a tensile load open the notches 13. Thus, the center of gravity z tensile reaction forces ZR runs in the middle of the distance h.

1 is clearly recognizable that the edge line of gravity r for the horizontal forces D, Z acting from the outside - seen in the vertical direction - runs between the center line of gravity z above it for the tensile reaction forces ZR and the center line of gravity d below for the pressure reaction forces DR.

This geometry ensures that, in the case of the pressure loading of the joint cover shown in FIG. 2, the elastomeric plate 2 is pressed down in the direction of the moments M1 and that even under tensile loads according to. Fig. 3 rectified moments M2 are generated. The particular course of the moment results inevitably from the vertical offset between the respective action and reaction force, namely in the case of FIG. 2 between the pressure force D narrowing the cover of the tongue and the pressure reaction force DR and in the case of FIG. 3 between the tensile force Z extending the cover of the joint and the associated tensile reaction force ZR. A slight curvature of the road surface 11 in the area of the elastomeric plate 2 is harmless in accordance with the course shown in dashed lines in FIGS. 2 and 3. It remains essential that the elastomeric plate 2 never lifts off its base.

The elastomeric plate 2 can either be prefabricated, i.e. installed together with the edge angles 4 in the joint area and then connected to the road surface 8; it can also be cast on site, whereby the edge notches 10 can be formed by foam strips inserted into the recess for the elastomeric plate 2. The cut notches 13 with fillets 14 can be produced by means of a lost formwork of approximately T-shaped cross-section rounded on the inside as shown in FIG. 1.

Both under pressure load acc. Fig. 2 as well as under load. Fig. 3 is the bottom 12 of the elastomeric plate 2 instead of on the gap 1 bridging base 15 made of rigid material such as steel or hard elastic plastic, so that the deformation of the cut notches 13 and the edge notches 10 is not hindered. While the edge notches 10 always remain open - according to the narrow joint position. Fig. 2 reduced, in the wide joint position. Fig. 3 enlarged accordingly - are the cut notches 13 under pressure load acc. Fig. 2 completely closed and under tensile load acc. Fig. 3 opened accordingly. When de-energized according to Fig. 1, the cut notches 13 are just closed, without the fillet 14 being reduced.

FIGS. 4 and 5 each show, in a vertical section transverse to the joint 1, a joint cover with only one notch 13, which merges into a particularly large cavity 16. The elastomeric plate 2 rests directly on the joint edges 6, 7. In this embodiment, the joint cover is particularly suitable for narrow joints. 4 shows the pressure force D and the pressure reaction force DR on the right half, the tensile force Z and the tensile reaction force ZR on the left half. It can easily be seen that the lines of gravity for the force attack run in the same way as for the exemplary embodiment according to FIG. specify Figures 1 to 3. These relationships result from the arrangement of a cut notch 13 and the two edge notches 10. Instead of the two edge notches, the center of gravity for the tensile force Z or the compressive force D in the edge region of the plate 2 can also be shifted to the upper plate region in another way. Correspondingly arranged hollow chambers have a similar effect as the edge notches 10. Such a hollow chamber 17 is shown in the left half of FIG. 5. Instead of arranging a notch or a hollow chamber in the lower region of the plate 2, the center of gravity is also shifted into the upper plate region by the fact that it is reinforced by additional measures, for example by a metal insert 18 shown in section in the right half of FIG. 5 4 and 5, for the sake of simplifying the drawing, the hatching of the elastomeric plate 2, which is shown in section, omitted. Of course, here too the elastomeric plate 2 is vulcanized with its lateral edges to the edge angles 4 anchored in the joint edges 6, 7.

Claims (5)

1. On the road surface joint cover in traffic routes, in particular of bridges, with an elastomeric plate (2) bridging the joint (1), the longitudinal edges of which are firmly connected to the associated joint edge (6,7), the plate (2) has at least one notch on its underside,
characterized,
that the notch is designed as a cut notch (13), which is almost or completely closed in the de-energized state of the plate (2), so that the entire plate cross-section acts in the case of compression deformations, while the cut notch (13) spreads out in the case of tensile deformations, essentially only the remaining plate cross section above the cut notch (13) acts. 2. Joint cover adjacent to the road surface in traffic routes, in particular of bridges, with an elastomeric plate (2) bridging the joint (1), the longitudinal edges of which are each firmly connected to the associated joint edge (6,7), the plate (2) has edge notches (10) adjacent to the longitudinal edges and at least one further notch,
characterized,
that the notch is designed as a cut notch (13), which is almost or completely closed in the de-energized state of the plate (2), so that the entire plate cross-section acts in the case of compression deformations, while the cut notch (13) spreads out in the case of tensile deformations, essentially only the remaining plate cross section above the cut notch (13) acts. 3. joint cover according to claim 1 doer 2,
characterized,
that the cut notch (13) merges into a rounding (14) or a cavity (16) at its inner end. 4. joint cover according to claim 2,
characterized,
that the edge notches (10) penetrate less deeply into the plate (2) than the cut notch (13). 5. joint cover according to claim 4,
characterized,
that the depth (t) of the cut notch (13) is between a third and a half of the plate thickness.

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