Joint Structure

Abstract

To provide a joint structure capable of preventing deterioration caused by load fluctuation induced by vertical steel plates of expansion devices that face each other across a joint gap part or guide plates connected to the vertical steel plates.SOLUTION: A part of a top side near an end face of floor slabs (1) that face each other across a joint gap part (2) is cut, vertical steel plates (4) arranged along an edge side extending in a direction perpendicular to a bridge axis of a joint installation face (3) formed at a position in the vertical direction below the surface of the floor slab are integrated with concrete (7) formed on the joint installation face, and the joint gap part is covered with a pavement face (10) formed by a mixture of a resin and an aggregate and provided on the floor slab or an elastic body layer (9) having a surface that is continuous with a surface of a concrete pressure boosting layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a joint structure provided between a superstructure and a ground structure in a bridge. [Background technology]

[0002] In bridges, steel expansion devices are widely used as joint structures between the superstructure and ground structure. Expansion devices form a gap between the superstructure and ground structure to adjust for bridge expansion and contraction caused by temperature differences, while allowing the wheel load of vehicles passing over the upper surface to pass through.

[0003] The wheel load of vehicles passing over the top of the expansion joint is applied to the deck via the steel material that constitutes the expansion joint, but depending on the structure of the expansion joint, the wheel load may be concentrated in a certain part of the deck, leading to early partial deterioration of the deck. Therefore, a method has been proposed to disperse the wheel load of vehicles passing over the top of the expansion joint.

[0004] For example, JP 2017-40052 A proposes an expansion device that distributes the load when it is applied from above to the connection of bridge members such as abutments and decks, and prevents localized load concentration. This expansion device can distribute the load applied downward from the road surface side by a load distribution means that is installed in a planar shape on the lower layer side of the overhanging member that is integrated with the bridge member by concrete. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP2017-40052A [Patent Document 2] JP 2012-225144 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0006] In conventional joint structures, a portion of the upper surface near the end faces of the deck slabs that are connected via the joint structure, facing each other across the gap, is cut out, and vertical steel plates that constitute the expansion device are arranged along the edge extending perpendicular to the bridge axis of the joint installation surface, which is formed at a vertically lower position than the surface of the deck slab.

[0007] The vertical steel plates form the opposing end surfaces across the gap, but they were installed with their upper surfaces exposed to the road surface, causing wheels passing over the gap to bounce off the road surface and generating impacts due to load fluctuations on the expansion joint.

[0008] Furthermore, conventional expansion devices, including the above-mentioned expansion device, which distribute the load applied downward from the road surface side, are unable to suppress the impact caused by the load fluctuation induced by the vertical steel plate, and are therefore unable to prevent deterioration caused by the load fluctuation.

[0009] In addition, in extension devices used in areas with heavy snowfall, a guide plate is provided to prevent the blade of the snow removal device mounted on a snowplow, which is located near the road surface, from getting caught on the vertical steel plate. The guide plate has a slope that slopes downward away from the vertical steel plate, but the area near the part connected to the guide plate is at the same height as the vertical steel plate, which induces load fluctuations in the same way as the vertical steel plate and is a cause of deterioration due to load fluctuations.

[0010] Therefore, an object of the present invention is to provide a joint structure that can suppress deterioration caused by load fluctuations induced by the vertical steel plates of the expansion devices facing each other across the gap or by guide plates connected to the vertical steel plates. [Means for solving the problem]

[0011] In the first joint structure of the present invention, a portion of the upper surface near the end face of the deck slabs facing each other across the gap is cut out, and a vertical steel plate arranged along the edge extending perpendicular to the bridge axis of the joint installation surface formed at a vertically lower position than the surface of the deck slab is integrated with the concrete formed on the joint installation surface, and the gap is covered with an elastic layer formed from a mixture of resin and aggregate and having a surface that is continuous with the pavement surface laid on top of the deck slab.

[0012] In the second joint structure of the present invention, a portion of the upper surface near the end face of the deck slabs facing each other across the gap is cut out, and a vertical steel plate arranged along the edge extending perpendicular to the bridge axis of the joint installation surface formed at a vertically lower position than the surface of the deck slab is integrated with the concrete formed on the joint installation surface, and the gap is covered with an elastic layer formed from a mixture of resin and aggregate and having a surface continuous with the surface of the concrete pressure-boosting reinforcement layer provided on top of the deck slab.

[0013] The joint structure of the present invention may be such that a guide plate extending in a direction away from the vertical steel plate and having an inclined surface descending from the surface height of the deck plate toward the joint installation surface is embedded in the concrete.

[0014] In addition, the joint structure of the present invention may be one in which an anchor bar protruding from the vertical steel plate in the bridge axis direction and a distribution bar arranged in a direction intersecting the anchor bar are embedded in the concrete. Effect of the Invention

[0015] According to the joint structure of the present invention, the elastic layer is formed from a mixture of resin and aggregate and has a surface that is continuous with the surface of the pavement surface or concrete pressure-boosting reinforcement layer placed on the deck slab, thereby mitigating the impact caused by load fluctuations induced by the vertical steel plates and suppressing deterioration caused by the load fluctuations. [Brief description of the drawings]

[0016] [Figure 1] 1 is a vertical cross-sectional view showing an outline of a joint structure according to the present invention. [Diagram 2]1 is a perspective view showing a state in which a vertical steel plate and a guide plate are arranged on a joint installation surface. FIG. [Diagram 3] FIG. 11 is a perspective view showing the vertical steel plates, anchor bars, and distribution bars that constitute the expansion device members of another joint structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An embodiment of the present invention will be described with reference to Figures 1 and 2. Note that in Figures 1 and 2, in order to facilitate understanding of the present invention, some parts are shown exaggeratedly for the sake of convenience, and the relative dimensions between parts are not accurate.

[0018] This embodiment assumes the connection of a new deck slab 1 in which the end faces in the bridge axis direction are arranged facing each other with a gap of 50 mm or less. In other words, the length dimension of the gap portion 2 in the bridge axis direction is 50 mm or less.

[0019] The deck 1 is made of reinforced concrete, and a portion of the upper surface near the end faces facing each other across the gap 2 is cut out to form a joint installation surface 3 that is vertically lower than the surface of the deck.

[0020] The thickness dimension of deck 1 is determined based on the deck span length and traffic volume. Specifically, where deck span length is L, it is calculated by multiplying the value obtained by (30 x L + 110) by an adjustment coefficient based on traffic volume. For example, if the deck span length is 2m and the planned traffic volume of large vehicles is 2000 or more in one direction per day, the thickness dimension is 210mm obtained by multiplying 170 (unit: mm) by the adjustment coefficient of 1.25 to get the value (212.5), and rounding off the first digit.

[0021] On the joint installation surface 3, vertical steel plates 4 which stand on the joint installation surface 3 and form the end surface of the deck slab, and multiple guide plates 5 connected to the vertical steel plates 4 are arranged.

[0022] The vertical steel plate 4 has a width dimension such that the height position of its upper end face when standing on the joint installation surface 3 is equal to the height position of the surface of the deck 1, and a length dimension equal to the dimension of the joint contact surface 3 in the direction perpendicular to the bridge axis. It stands along the edge of the joint installation surface 3 extending in the direction perpendicular to the bridge axis, and forms the end face of the deck 1.

[0023] The guide plate 5 is a steel plate material like the vertical steel plate 4, and the surface that is placed on the upper side when installed on the joint installation surface 3 is shaped to form an inclined surface 6 that descends from the surface height of the deck 1 toward the joint installation surface 3. In this embodiment, a right-angled trapezoidal notch is added to the middle of one long side of the rectangular steel plate, and a right-angled triangular notch with a hypotenuse parallel to the hypotenuse of the right-angled trapezoid is added to one end of the other long side. The long side with the right-angled triangular notch forms the inclined surface 6 that descends from the surface height of the deck slab 1 toward the joint installation surface 3.

[0024] The guide plates 5 are also arranged at predetermined intervals in the direction perpendicular to the bridge axis, and are welded to the vertical steel plate 4 with their inclined surfaces 6 facing downward and away from the vertical steel plate 4. Note that, although five guide plates 5 are shown in Fig. 2, there are no restrictions on the number or spacing of the plates, and they may be determined according to the traffic volume and size of the bridge on which the joint structure is to be installed.

[0025] Furthermore, the vertical steel plate 3 and guide plate 5 arranged on the joint installation surface 3 are integrated with the concrete 7 extending from the joint installation surface 3 to the surface height of the deck slab 1, and together with the concrete 7 constitute an expansion device member 8.

[0026] In addition, it is preferable to apply an adhesive to the surfaces of the vertical steel plate 3 and the guide plate 5 in order to more firmly integrate them with the concrete 7. This improves the adhesive strength between the steel material and the concrete, and improves durability. 2 The above epoxy-based adhesives are suitable.

[0027] The pair of expansion device members 8 are disposed with the gap portion 2 therebetween. The pair of expansion device members 8 and the gap portion 2 are covered with an elastic layer 9.

[0028] The elastic layer 9 is formed from a mixture of resin and aggregate, and has a surface that is continuous with the pavement surface 10 that is laid on the deck 1. There are no restrictions on the resin and aggregate used, and they can be determined according to the traffic volume and weather conditions of the road on which the joint structure is to be installed. However, the elastic layer 9 must allow expansion and contraction within the same length range as the gap 2 (-25 to +25 mm when the gap 5 is 50 mm), and must have a compressive strength equal to or greater than that of the pavement that forms the pavement surface 10.

[0029] When the length of the gap 2 in the bridge axis direction is 50 mm or more, it is preferable to enhance the load-supporting function of the expansion device member 8. The arrangement of reinforcing bars used for this purpose is shown in FIG.

[0030] In the reinforcing bar arrangement structure shown in Figure 3, instead of the guide plate 5 used in the joint structure shown in Figures 1 and 2, an anchor bar 11 protruding from the vertical steel plate 5 in the bridge axis direction and a distribution bar 12 arranged in a direction intersecting the anchor bar 11 constitute an expansion device member 8.

[0031] 1 and 2 are intended to connect a newly constructed deck 1, but the joint structure according to the present invention can also be installed as a replacement for an existing expansion device. In this case, however, it is necessary to maintain the necessary strength for the elastic layer 9, and for this purpose, it is preferable to use aggregate having a thickness of 15 to 20 mm for forming the elastic layer 9, and to set the thickness of the elastic layer 9 to 30 mm or more.

[0032] For example, a steel expansion device with a height of 100 mm is generally widely used as an expansion device with a design strength taking into account traffic volume and bridge scale. When replacing this steel expansion device, it is preferable to limit the height dimension of the expansion device member 8 to 70 mm by thickening the cross section of the steel material, and to set the thickness dimension of the elastic layer 9 to 30 mm.

[0033] Furthermore, it is preferable that the thickness of the elastic layer 9 is approximately 30% of the total thickness of the joint structure, which is the sum of the thickness of the elastic layer 9 and the thickness of the expansion device member 8 .

[0034] For example, if the height dimension of the existing expansion device is 150 mm, the thickness dimension of the elastic layer 9 is determined in the range of 30 to 60 mm, and the height dimension of the expansion device member 8 may be set to a value obtained by subtracting the thickness of the elastic layer 10 from 150 mm, that is, a value in the range of 120 to 90 mm.

[0035] Furthermore, in some cases, cutting of the deck slab is required when removing an existing expansion device, and in such cases, the thickness dimension of the elastic layer 9 may be increased by the amount of cutting. For example, if a 100 mm high existing steel expansion device is cut to a thickness of 20 mm when removing it, and the height dimension of the expansion device member 8 is 70 mm, the thickness dimension of the elastic layer 9 may be 50 mm. Also, if the height dimension of the expansion device member 8 is 80 mm, the thickness dimension of the elastic layer 9 may be 40 mm.

[0036] In the embodiment shown in Figures 1 and 2, the elastic layer 9 has a surface that is continuous with the pavement surface 10 provided on the deck slab 1, but it may also have a surface that is continuous with the surface of the concrete pressure-boosting reinforcement.

[0037] In order to improve the load-bearing capacity and fatigue resistance of RC decks, concrete reinforcement of 40mm to 60mm thickness is sometimes applied to the RC decks, and in this reinforcement method, the existing expansion joint is removed and a new expansion joint is installed. Even in such a case, an elastic layer with a thickness dimension that matches the thickness reinforcement dimension, that is, a surface that is continuous with the surface of the concrete pressure-increasing reinforcement, may be installed on top of the newly installed expansion joint. [Explanation of symbols]

[0038] 1 floor slab 2. Joint 3. Joint installation surface 4 Vertical steel plate 5 Guide plate 6 Slope 7. Concrete 8 Expansion device members 9 Elastic layer 10. Pavement 11 Fixation muscles 12 Reinforcement

Claims

1. A joint structure characterized in that a portion of the upper surface near the end face of the deck slabs facing each other across the gap is cut out, and a vertical steel plate is arranged along the edge extending perpendicular to the bridge axis of a joint installation surface formed at a vertically lower position than the surface of the deck slab, and is integrated with the concrete formed on the joint installation surface, the gap is covered with an elastic layer formed from a mixture of resin and aggregate and having a surface that is continuous with the pavement surface laid on top of the deck slab, and a guide plate extending in a direction away from the vertical steel plate and having a sloping surface that descends from the surface height of the deck slab toward the joint installation surface is embedded in the concrete.

2. A joint structure characterized in that a portion of the upper surface near the end face of the deck slabs facing each other across the gap is cut out, and a vertical steel plate is arranged along the edge extending perpendicular to the bridge axis of a joint installation surface formed at a vertically lower position than the surface of the deck slab, and is integrated with the concrete formed on the joint installation surface, the gap is covered with an elastic layer formed from a mixture of resin and aggregate and having a surface continuous with the surface of the concrete pressure-boosting reinforcement layer provided on the deck slab, and a guide plate extending in a direction away from the vertical steel plate and having a sloping surface descending from the surface height of the deck slab toward the joint installation surface is embedded in the concrete.

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