An expansion joint, and an elastically yielding member for use in an expansion joint

Abstract

 The invention concerns an expansion joint (10) for installation across a gap between adjacent concrete slabs (2, 2') in a civil engineering structure, the slabs (2, 2') having in the area of said gap a front side (3, 3'), the expansion joint (10) including i) an elongated rigid bridging member (15) for spanning said gap and ii) elongated elastically yielding members (35, 35') yielding elastically in response to dimensional changes of said slabs (2, 2') and adjoining said bridging member (15), the elastically yielding members (35, 35') being adapted to be supported by a respective concrete slab (2, 2') near said front side (3, 3'). The elastically yielding members (35, 35') are preformed blocks that include means for the connection thereof to the bridging member (15) as well as to the respective concrete slab (2, 2').

Description

[0001] The present invention is related to an expansion joint for installation across the gap between adjacent concrete slabs in a civil engineering structure, such as a car parking building, the expansion joint including i) an elongated rigid bridging member for spanning the gap and ii) elongated members that yield elastically in response to dimensional changes of the slabs and that adjoin the bridging member, the elastically yielding members being supported by a respective concrete slab. The invention is also related to an elastically yielding member for use in an expansion joint.

[0002] US 5 791 111 discloses a sealing device involving the use of a preformed block-shaped elastically yielding member for spanning the gap between two adjoining concrete slabs in a building structure. This solution is disadvantageous in that the elastically yielding member is unsupported in the area of the gap, the weight of a travelling vehicle generating high internal tensile stresses within the elastically yielding member, adding to the internal stresses arising from the dimensional changes of the concrete slabs.

[0003] Moreover, an expansion joint typically used for car-park decks is already known, the bridging member being a narrow concrete plate. An elastically yielding sealant is arranged in the groove between the concrete plate and an adjoining layer of a bituminous material placed on the upper surface of each concrete slab. This solution involves disadvantages in that the sealant may loosen contact with the bituminous layer or with the bridging member when the concrete slabs contract, leading to the risk of water flowing into the gap between the concrete slabs or, when the slabs expand, that the sealant may be to heavily compressed and flow out of the groove, leading again to a loss of the seal.

[0004] In accordance with the invention the aforementioned problems are solved in that the elastically yielding members are preformed blocks that include connection means for the connecting the elastically yielding members to the bridging member as well as to the respective concrete slab.

[0005] The elastically yielding members may be directly or indirectly connected to the concrete slabs. Preferably, the expansion joint includes supporting plates upon which the yielding members rest and which are connected to a respective concrete slab, the yielding members being connected to the respective supporting plate by the connection means, an indirect connection between the elastically yielding members and the respective concrete slab thereby being established.

[0006] According to a preferred embodiment each elastically yielding member has opposed elongated side strips that form sides of the elastically yielding member and that are integrally connected by a central part of said elastically yielding member, the connection to the bridging member and the concrete slab being in the side strips and the side strips being more rigid than the central part whereby dimensional changes of the slabs mainly result in dimensional changes of the central part. This allows for a highly reliable connection even when the elastically yielding member is highly compressed or extended.

[0007] According to a further embodiment, the central part has a plurality of recesses formed in the surface thereof in accordance with a particular pattern. Walls extending perpendicularly to the upper and/or lower surface of the central part separate the recesses and transfer vertical loads from vehicles travelling on the central part to the underlying concrete slab. One advantage of this is that the upper surface of the central part will remain essentially level with the bridging member even when subjected to high compressive or tensile forces arising from temperature induced dimensional changes in the concrete slabs. By an appropriate dimensioning of the walls, the central part may be made highly dimensionally stable with regard to vertical forces.

[0008] Preferably, the elastically yielding members are provided with grooves receiving projecting parts mounted on the bridging member for providing for an easy assembly of the expansion joint without the need for specialized tools.

[0009] In the following, a presently preferred embodiment of the invention will be discussed with reference to the drawing.

Fig. 1 shows a section through the area between two adjacent concrete slabs,

Fig. 2 shows the expansion joint 10 of fig. 1 in further details,

Fig. 3 shows, in more details, the elastically yielding members,

Fig. 4a and 4b show the elongated bridging member in more details, and

Fig. 5 shows one of the supporting plates in greater details.

[0010] Fig. 1 shows a section through the area between two adjacent concrete slabs 2, 2' which may be structural parts of a building, such as a parking facility, of a road or of any other civil engineering construction. The concrete slabs 2, 2' are each covered on the top surface 4, 4' by a layer 5, 5' of a bituminous material, or any similar material suitable as a weather protection and preferably having the properties normally required for a road pavement. The concrete slabs 2, 2' are placed with their front sides 3, 3' facing each other with an intermediate gap allowing for an expansion of the concrete slabs 2, 2' caused by increases in the ambient temperature.

[0011] To allow for a smooth passage of vehicles over the gap an expansion joint according to the invention identified generally by the reference numeral 10 is connected to each concrete slab 2, 2' at the aforementioned gap. The expansion joint 10 is secured to the concrete slabs 2, 2' by means of appropriate fastening devices, such as screws or nails 12, 12', and the layer 5, 5' forming the weather protection, and, as the case may be, the road pavement, lies against the sides of the expansion joint 10. It will be understood that the expansion joint 10 is elongated in the sense that it has a major extension out of the plane of fig. 1, preferably an extension which corresponds to the extension out of the plane of fig. 1 of the front sides 3, 3' of the slabs 2, 2', i.e. normally in the lengthwise direction of the concrete slabs 2, 2'.

[0012] Fig. 2 shows the expansion joint 10 of fig. 1 in further details. The drawing shows a preferred installation of the expansion joint 10 wherein a soft elastomeric cord 7 and a water-tight membrane 8 has been placed on the top surface 4, 4' of the concrete slabs 2, 2' before placing the expansion joint 10. The expansion joint 10 is formed from five elongated elements 15, 25, 25', 35, 35', namely two preformed block-shaped elastically yielding members 35, 35' that are each anchored on a supporting plate 25, 25' connected to a respective concrete slab 2, 2'. By "elastically yielding" as used herein is generally meant an element that will yield in the direction indicated by the arrows A, A' in fig. 1 in accordance with the dimensional changes of the slabs 2, 2', the resiliency being determined by the selected material, the structure of the element, or a combination thereof. Moreover, the term "elastic" as used herein refers to the ability of an element to return to the same or essentially the same position upon a load being released. The elastically yielding members 35, 35' should be capable of supporting traffic rolling across the expansion join 10 and should be dimensionally stable to at least a certain extend with regard to vertical loads irrespective of the ambient temperature. It is preferred that the block-shaped elastically yielding members 35, 35' are made from an elastomeric material, preferably rubber and most preferred black vulcanized rubber, in a moulding operation.

[0013] Firmly anchored to the preformed block-shaped elastically yielding members 35, 35' near the sides 82, 82' thereof is a rigid bridging member 15 which bridges the gap between the concrete slabs 2, 2'. The bridging member 15 and the supporting plates 25, 25' may be made by extrusion of metal or by pultrusion of a fibre reinforced synthetic material while the elastically yielding members 35, 35' may be made from any conventional elastomeric material. It will be understood that expansion and contraction of the slabs 2, 2' leads to a change in the distance between the area where each elastically yielding members 35, 35' is secured to the supporting plate 25, 25' and the bridging member 15. By the term "rigid" as used herein with respect to the bridging member 15 is meant that this element will yield less in the direction indicated by the arrows A, A' in fig. 1 than the elastically yielding members 35, 35' when the expansion joint 10 is subjected to forces in that direction, such as when the slabs 2, 2' expand or contract due to temperature variations. Using a bridging member 15 manufactured by pultrusion of a fibre reinforced synthetic material provides highly dimensionally stable qualities. The bridging member 15 must also be capable of transmitting the vertical loads of vehicles travelling thereon to the slabs 2, 2' via the elastically yielding members 35, 35', and is dimensioned, such as by the use of reinforcements, to limit downward deflections in the area above the gap between the concrete slabs 2, 2' where the bridging member 15 is unsupported.

[0014] As mentioned, the elastically yielding members 35, 35' are secured to a respective slab 2, 2' via a supporting plate 25, 25', this connection being near the side 80, 80' of the elastically yielding members remote from the bridging member 15. The upper surface of the supporting plates 25, 25' supporting the elastically yielding members 35, 35' preferably provide a low frictional resistance against relative movements of the elastically yielding members 35, 35' with respect to the supporting plates 25, 25' whereby resistance to dimensional changes of the elastically yielding members 35, 35' in direction A, A' mainly arises from the compressive or tensile forces generated within the elastically yielding members 35, 35'.

[0015] As shown in more details in fig. 3, the elastically yielding members 35, 35' each have a series of elongated recesses or grooves 38, 38', 40, 40' allowing for the elastically yielding members 35, 35' to be secured to the bridging member 15 and to the concrete slab 2, 2' above which the respective elastically yielding member 35, 35' is located. In the preferred embodiment shown in the drawing the elastically yielding members 35, 35' are secured directly to the bridging member 15 and to the respective supporting plate 25, 25' in the sense that no separate fastening means are used. For this purpose, the bridging member 15 as well as the supporting plates 25, 25' may be integrally formed with elongated projecting engaging elements 17, 29, 29' receivable by said recesses or grooves 38, 38', 40, 40'. In the event that no supporting plates 25, 25' are used whereby the elastically yielding members 35, 35' would be supported directly by the concrete material of the slabs 2, 2' or by a membrane 8, corresponding engaging members 29, 29' receivable by the grooves 40, 40' may be secured directly to the concrete slabs 2, 2'.

[0016] The elastically yielding members 35, 35' are preferably formed as a single body including elongated side strips 36, 36', 37, 37' integrally formed with a central part 39, 39' having a structure comprising a series of elongated recesses 42, 42', 46, 46' extending from the upper surface to a depth defined by respective surfaces of ribs 50, 50', 51, 51' that also define the extension from the lower surface of the central part 39 of further recesses 52, 52', 56, 56'. The recesses 42, 42', 46, 46', 52, 52', 56, 56' are preferably parallel, and run at an angle θ of 25°-55°, preferably about 30°, with respect to the longitudinal extension of the elastically yielding members 35, 35', i.e. with respect to the extension of the parallel sides 80, 80', 82, 82' of the elastically yielding members 35, 35'. In the mounted state of the expansion joint 10, the recesses 42, 42', 46, 46', 52, 52', 56, 56' in the elastically yielding members provide the expansion joint 10 with an overall dart-like appearance when seen from above in the sense that the recesses on the two sides of the bridging member 15 point towards the same end of the bridging member 15, i.e. the recesses on formed in member 35 preferably do not run parallel with the recesses in member 35', although the same angle θ is preferably selected.

[0017] In the elastically yielding members 35, 35', the ribs 50, 50', 51, 51', that are preferably horizontal, together with the vertical walls 44 that separate the recesses 42, 42', 46, 46', 52, 52', 56, 56' connect the strips 36, 36', 37, 37' with one another. It will be understood that this structure, i.e. the arrangement and dimensions of the ribs 50, 50', 51, 51', is a factor in obtaining the desired elastic properties of the elastically yielding members 35, 35' with respect to a compression in direction A, A' marked on fig. 1, the main dimensional changes occurring in the central part 39, 39'. In use, when traffic passes over the expansion joint 10, the vertical walls 44, 44' of the central part 39, 39' transfer vertical forces directly to the supporting plates 25, 25'. Obviously, if no supporting plates 25, 25' are used, the elastically yielding members 35, 35' would rest directly on the concrete slabs 2, 2', or the membrane 8 if one such is used, and then transfer the vertical forces directly to the concrete slabs 2, 2'.

[0018] Fig. 4b shows the elongated bridging member 15 in more details. As shown, this member has the shape of an inverted U with a web 16 and opposed flanges 17. The flanges 17 are dimensioned to be receivable by the elongated groove 38, 38' in a respective elastically yielding member 35, 35' with a certain clamping force being applied on the flanges 17 due to the grooves 38, 38' preferably being of a smaller width than the flanges 17. If required, an adhesive 120, 120' may be applied in the grooves 38, 38' (see fig. 2). Since compression and extension of the elastically yielding members 35, 35' gives rise to the largest deformations occurring in the central part 39, 39' of the elastically yielding members 35, 35', the aforementioned clamping force will generally be maintained when the slabs 2, 2' contract. To provide a good contact between the bridging member 15 and the elastically yielding members, the strips 36, 36' nearmost the groove 38, 38' receiving the flanges 17 have a slightly inclined upper surface matching an inclined elongated surface area 20 (see fig. 4a) on the bottom of the web 16 of the bridging member 15, these surfaces touching one another at least to some degree even when the elastically yielding members 35, 35' are deformed. As shown in fig. 4b, the bridging member 15 may be formed with anti-skid surface areas 18 on the upper surface of the web 16, allowing for a safe passage of vehicles and pedestrians.

[0019] Fig. 5 shows one of the supporting plates 25, 25' in greater details, illustrating that these plates are preferably formed integrally with two projecting ribs 27, 27', 29, 29' of which one ribs 29, 29' serves as an engaging element receivable in the aforementioned groove 40, 40' in the elastically yielding members 35, 35'. The supporting plates 25, 25' include two surface areas 31, 31', 32, 32' of which at least the one surface area 31, 31' supporting the central part 39, 39' of the elastically yielding members 35, 35' is smooth to provide a low frictional resistance as has been mentioned. The other surface area 32, 32' is provided with a series of through-going apertures 26, 26' receiving screws or nails 12, 12' for securing the supporting plates 25, 25' to the concrete slabs 2, 2', preferably with a washer 13, 13' being applied for water tightness. The location of the through-going apertures 26, 26' with respect to the front edge 126, 126' of the supporting plates 25, 25' is selected to ensure that the supporting plates 25, 25' may be connected to the respective concrete slab in an area where the latter has a low number of reinforcing bars, ie. at some distance from the front side 3, 3'. The two projecting ribs 27, 27', 29, 29' define there-between an elongated groove 30, 30' for securing the elastically yielding members 35, 35'. More specifically, by arranging the groove 40, 40' in the elastically yielding members 35, 35' at a distance from the side 80, 80' corresponding to about the width of the elongated groove 30, 30', a clamping force maintaining the elastically yielding members 35, 35' in place on the supporting plates 25, 25' may be generated. To further increase this clamping force, the groove 30 may have a smaller width I at the mouthing as compared with the width L at the groove bottom 11. Through deformation of the part of the strips 37, 37' received in the groove 30, 30', a highly reliable connection is obtained.

[0020] As mentioned, the layer 5, 5' forming the weather protection and in the relevant case also the road pavement preferably lies directly against the sides 80, 80' of the expansion joint 10. Although normally not required, a sealant may be applied in this area, no significant strains potentially damaging the sealant arising from a contraction of the slabs 2, 2' since the expansion joint 10 is immovably connected to the slabs by the fastening devices 12, 12'.

[0021] As will be seen, the invention involves the further advantage that, after installation of the supporting plates 25, 25', the elastically yielding members 35, 35' and the bridging member 15 may be installed without the need for complicated tools by means of the engaging projections 17, 29, 29' formed on the bridging member 15 and the supporting plates 25, 25', respectively. Moreover, for repair or inspection, the expansion joint 10 may easily be disassembled partially since no mechanical fasteners, other than the screws 12, 12', are used. When using the aforementioned adhesive 120, 120' this should preferably be applied so as to keep the bridging member 15 in position in normal daily use while still permitting removal of the bridging member 15 without any significant effort. The various parts of the expansion joint may be manufactured in lengths as appropriate, eg. in 1 meter lengths.

[0022] It is noted that the supporting plates 25, 25' although having been described as being screwed to the concrete slabs 2, 2' may alternatively be secured by use of any appropriate adhesive. Likewise, the elastically yielding members 35, 35' may be connected to the supporting plates 25, 25', or to the concrete slabs 2, 2' as the case may be, by applying an adhesive along the lower surface of the side strips 37, 37', although this solution is presently not being preferred. Moreover, the expansion joint 10 according to the invention may be used with or without any water-tight membrane 8 being applied on the concrete slabs 2, 2'.

Claims

1. An expansion joint (10) for installation across a gap between adjacent concrete slabs (2, 2') in a civil engineering structure, said slabs (2, 2') having in the area of said gap an upper surface (4, 4') and a front side (3, 3'), said expansion joint (10) including i) an elongated rigid bridging member (15) for spanning said gap and ii) elongated elastically yielding members (35, 35') yielding elastically in response to dimensional changes of said slabs (2, 2') and adjoining said bridging member (15), said elastically yielding members (35, 35') being adapted to be supported by a respective concrete slab (2, 2') near said front side (3, 3') and having an upper surface and a lower surface,
characterised in
that the elastically yielding members (35, 35') are preformed blocks that include means for the connection thereof to the bridging member (15) as well as to the respective concrete slab (2, 2').

2. An expansion joint according to the preceding claim, characterised in an elongated supporting plate (25, 25') resting on each of said slabs (2, 2') and connected thereto, each elastically yielding member (35, 35') resting on a corresponding one of said elongated supporting plates (25, 25') and being connected thereto.

3. An expansion joint according to any of the preceding claims, said elastically yielding members (35, 35') being substantially dimensionally stable with regard to loads perpendicular to said upper surfaces (4, 4').

4. An expansion joint according to any of the preceding claims, said elongated elastically yielding members (35, 35') having opposed sides (80, 82; 80', 82') and an elongated central area (39, 39') there-between, said elastically yielding members (35, 35') being connected to said bridging member (15) near one of said sides (82, 82') and to the concrete slabs (2, 2') near the other side (80, 80').

5. An expansion joint according to any of the preceding claims 1-3, said elastically yielding members (35, 35') having opposed elongated side strips (36, 36' 37, 37') forming sides (80, 82; 80', 82') of said elastically yielding member (35, 35') and connected by a central part (39, 39') of said elastically yielding members (35, 35'), said connection to said bridging member (15) 82') and said concrete slab (2, 2') being in said side strips (36, 36' 37, 37'), said side strips (36, 36', 37, 37') being more rigid than said central part (39, 39') whereby dimensional changes of said slabs (2, 2') mainly result in dimensional changes of said central part (39, 39').

6. An expansion joint according to the preceding claim, said elastically yielding members (35, 35') being moulded of materials having different elastic properties, one material forming the side strips (36, 36', 37, 37') and another said central part (39, 39').

7. An expansion joint according to claim 5 or 6, said central part (39, 39') preferably being of an elastomeric material and having a plurality of recesses (42, 42', 46, 46', 52, 52', 56, 56') formed in said upper and/or lower surface of said elastically yielding members (35, 35').

8. An expansion joint according to claim 7, said recesses (42, 42', 46, 46', 52, 52', 56, 56') defining grooves separated by walls (44, 44') extending perpendicularly or essentially perpendicularly to said upper and/or lower surface of said elastically yielding members (35, 35').

9. An expansion joint according to claim 8, said grooves extending at an angle θ of 25°-55°, preferably 30° or about 30°, with respect to the longitudinal extension of said side strips (36, 36' 37, 37').

10. An expansion joint according to any of the preceding claims, said means for connecting the elastically yielding members (35, 35') to the bridging member (15) and to the respective concrete slab (2, 2') being ribs (29, 29', 17) engaging complementary elongated grooves (38, 38', 40, 40').

11. An expansion joint according to the preceding claim, said elastically yielding members (35, 35') having said grooves (38, 38', 40, 40'), said bridging member (15) having said ribs (17).

12. An expansion joint according to claim 2 and any claim dependent thereon, said connection between said elastically yielding members (35, 35') and said concrete slabs (2, 2') thereto being indirect.

13. An expansion joint according to the preceding claim, said means for connecting the elastically yielding members (35, 35') to the bridging member (15) and to the respective concrete slab (2, 2') being ribs (29, 29', 17) engaging complementary elongated grooves (38, 38', 40, 40'), said elastically yielding members (35, 35') having said grooves (38, 38', 40, 40') and said bridging member (15) and supporting plates (25, 25') having said ribs (29, 29', 17) engaging said grooves (38, 38', 40, 40').

14. An elastically yielding member (35, 35') for use in an expansion joint and for connection to an elongated rigid bridging member (15) spanning the gap between two adjacent concrete slabs (2, 2'), said elastically yielding member (35, 35') having opposed elongated side strips (36, 36' 37, 37') forming sides (80, 82; 80', 82') of said elastically yielding member (35, 35') and connected by a central part (39, 39') of said elastically yielding member (35, 35'), said side strips (36, 36', 37, 37') being more rigid than said central part (39, 39') whereby dimensional changes of said slabs (2, 2') mainly result in dimensional changes of said central part (39, 39').

15. An elastically yielding member (35, 35') according to the preceding claim, moulded of materials having different elastic properties, one material forming the side strips (36, 36', 37, 37') and another said central part (39, 39').

16. An elastically yielding member (35, 35') according to claim 14 or 15, said central part (39, 39') preferably being of an elastomeric material and having a plurality of recesses (42, 42', 46, 46', 52, 52', 56, 56') formed in said upper and/or lower surface of said elastically yielding member (35, 35').

17. An elastically yielding member (35, 35') according to claim 16, said recesses (42, 42', 46, 46', 52, 52', 56, 56') defining grooves separated by walls (44, 44') extending perpendicularly or essentially perpendicularly to said upper and/or lower surface of said elastically yielding member (35, 35').

18. An elastically yielding member (35, 35') according to claim 17, said grooves extending at an angle θ of 25°-55°, preferably 30° or about 30°, with respect to the longitudinal extension of said side strips (36, 36' 37, 37').

Drawing