Joint part bar arrangement structure with use of spiral reinforcement bar

Abstract

To provide a joint part bar arrangement structure with which, when a joint part is formed using a spiral reinforcement bar, a joint part capable of being reinforced to secure required strength can be easily materialized and workability in casting concrete can be improved.SOLUTION: A spiral reinforcement bar 10 is placed in a concrete-casting space of a joint part 22 with such arrangements that the three side parts 11a, 11b, 11c positioned on the imaginary base surface P of a unit of spiral reinforcement bar 11 are placed in the interval portions of alternately-arranged joint reinforcement bars 21; diagonal linkage bars 11d are arranged crossing the upper reinforcement bars 21a of the joint reinforcement bars 21; and the spiral reinforcement bar 10 and the joint reinforcement bars 21 are bound with binding wires 12 with the three side parts 11a, 11b, 11c positioned on the imaginary base surface P being pushed to one side close to or contacting either one of the joint reinforcement bars 21 located at both sides of the interval portion.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a reinforcement structure of a joint using spiral reinforcing bars, and in particular to a reinforcement structure of a joint using spiral reinforcing bars that is provided in the concrete pouring space of a joint between a pair of adjacent concrete slabs. [Background technology]

[0002] In recent years, many large-scale renovation projects have been ordered, for example, to address the deterioration of concrete decks of existing road bridges by replacing the decks. Furthermore, for renovation work involving concrete deck replacement, rectangular precast PC decks made of precast concrete are commonly used to reduce construction labor and shorten construction time. In renovation work using precast PC decks, for example, on existing road bridges, the road bridge piers have columns extending vertically from the ground and beams extending to the left and right from the columns. Multiple girders are installed between the beams of adjacent piers in the bridge axis direction. The precast PC deck, which forms the main part of the road, is supported by multiple girders installed at predetermined intervals in a direction perpendicular to the bridge axis direction, with its long sides preferably aligned perpendicularly to these girders and installed in a continuous manner in the bridge axis direction.

[0003] In addition, the precast PC deck slabs are supported by multiple bridge girders and installed in a series in the bridge axis direction, and are integrated by placing steel bars and pouring concrete at the joints along the long sides between each pair of adjacent precast PC deck slabs in the bridge axis direction.

[0004] For this reason, in the conventional general joint structure, multiple loop-shaped joint reinforcements (loop joints) are preferably used as joint reinforcement from the end face along the long side of the installed precast PC deck slab. These loop joint reinforcements are then attached to adjacent pairs of precast PC floors. The loop joint reinforcement bars are arranged alternately at the joint between the slabs, and long, straight connecting main reinforcement bars that connect the loop joint reinforcement bars are inserted inside the annular parts of the alternately arranged loop joint reinforcement bars that overlap when viewed from the length direction of the joint reinforcement, in the length direction of the joint reinforcement along the long side part, and after arranging the reinforcement in the specified position, concrete is poured into the joint reinforcement, which is a joint reinforcement structure that is formed.

[0005] On the other hand, in the conventional general joint structure described above, the work of inserting long main reinforcement bars inside the ring-shaped portion where the alternately arranged, preferably loop joint reinforcement bars, overlap, and the work of arranging the inserted long main reinforcement bars at the designated position in the ring-shaped portion requires a lot of time and effort, such as setting up a special overhanging scaffold on the side of the bridge girder, holding long, straight reinforcing bars from the overhanging scaffolding and inserting them inside the ring-shaped portion, inserting the reinforcing bars through reinforcing bar insertion ports set up at the bridge girder position, and tying the reinforcing bars inserted inside the ring-shaped portion into the designated position while lifted up, so a technology has been proposed that makes this work unnecessary (see, for example, Patent Document 1).

[0006] According to the joint structure of the precast deck in Patent Document 1, the joint reinforcing bars are arranged alternately between a pair of adjacent precast PC decks, and preferably spiral reinforcing bars are dropped from above to be fitted into the gaps between each of the loop-shaped reinforcing bars, thereby making it possible to pre-install long, straight connecting main bars that connect the loop-shaped reinforcing bars outside the annular portion where the alternately arranged loop joint reinforcing bars overlap. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-49621 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the joint structure of the precast deck slab described in Patent Document 1, the spiral reinforcing bars (spiral reinforcing bars) have a constant helix angle relative to the central axis and a circular frontal shape when viewed from the axial (longitudinal) side. This makes on-site positioning of the reinforcing bars at the joint cumbersome. Furthermore, the extent of the concrete restraint effect of the spiral reinforcing bars is limited to a circular area, preferably inside the annular portion, where the alternately arranged joint reinforcing bars, e.g., loop joint reinforcing bars, overlap. This makes it impossible to omit the linear connecting main reinforcing bars, e.g., outside the annular portion where the loop joint reinforcing bars overlap. Furthermore, when forming joints in precast deck slabs using spiral reinforcing bars, it is desirable to easily obtain a reinforcing structure for the joint that can ensure the required strength. In particular, because the reinforcing bars at the joints are entangled by the joint reinforcing bars and spiral reinforcing bars, it is desirable to consider ease of construction when pouring concrete.

[0009] The present invention aims to provide a reinforcement structure for a joint using spiral reinforcing bars that can be easily obtained to reinforce the joint so as to ensure the necessary strength when forming a joint in a precast deck using spiral reinforcing bars, which enable smooth positioning and reinforcement at the joint between a pair of adjacent concrete slabs, preferably precast PC decks, and which allows for the omission of straight connecting main bars that connect the joint reinforcing bars to each other by expanding the range over which the restraining effect of the concrete extends, and which can improve workability when pouring concrete. [Means for solving the problem]

[0010] The present invention is a reinforcement structure using spiral reinforcing bars, which is provided in the concrete pouring space of a joint between a pair of adjacent concrete slabs, and the spiral reinforcing bars are formed by bending a single reinforcing bar, so that a plurality of unit spiral reinforcing bars, each having a rectangular front view, are provided with a spiral shape in which they are continuous at a predetermined pitch in the axial direction of the spiral, and each of the continuous unit spiral reinforcing bars has a pair of left and right short side portions and one long side portion of the rectangular front view that are arranged on an imaginary reference plane, and the other long side portion is an oblique connecting bar that extends in a direction inclined at an angle of 10 to 35 degrees when viewed from above with respect to the imaginary reference plane on which these three side portions are arranged, thereby forming a Z-spiral shape with a continuous Z shape when viewed from above, and protruding from the end faces of the concrete slabs on both sides facing each other in the concrete pouring space of the joint, respectively, and including upper reinforcing bars and lower reinforcing bars. The above-mentioned object has been achieved by providing a reinforcement structure for a joint using a spiral reinforcing bar, in which the joint reinforcing bars are arranged in two stages, with the joint reinforcing bars protruding from one end face of the concrete slab and the joint reinforcing bars protruding from the other end face of the concrete slab being arranged alternately in a staggered pattern in the length direction of the joint, and the three side portions of the spiral reinforcing bar arranged on the imaginary reference plane are arranged in the spaces between the alternately arranged joint reinforcing bars, and the diagonal connecting bars are arranged so as to intersect with the upper reinforcing bars of the joint reinforcing bars, and the three side portions arranged on the imaginary reference plane are connected to the spiral reinforcing bar in a state where they are close to or in contact with one of the joint reinforcing bars on both sides of the spaces, thereby providing a reinforcement structure for a joint using a spiral reinforcing bar, in which the spiral reinforcing bar is attached to the concrete pouring space of the joint.

[0011] Furthermore, it is preferable that the reinforcement structure of the joint section using the spiral reinforcing bar of the present invention has the virtual base surface which is a plane perpendicular to the axial direction of the spiral, and that the upper reinforcing bar and the lower reinforcing bar of the joint reinforcing bar protrude in a direction perpendicular to the end face of the concrete slab when viewed from above.

[0012] Furthermore, it is preferable that the reinforcement structure of the joint section using the spiral reinforcing bars of the present invention is such that the joint section between a pair of adjacent concrete slabs is a joint section formed between a pair of adjacently installed precast PC deck slabs.

[0013] Furthermore, it is preferable that the reinforcement structure of the joint section using the spiral reinforcement of the present invention is such that the three side portions arranged on the virtual base surface are arranged alternately in the spaces between the alternately arranged joint reinforcement bars.

[0014] Furthermore, in the reinforcement structure of the joint section using the spiral reinforcing bars of the present invention, it is preferable that the reinforcing bars for the joint section are connected between the end of the upper reinforcing bar and the end of the lower reinforcing bar via an arc-shaped portion.

[0015] In addition, it is preferable that the reinforcement structure of the joint section using the spiral reinforcing bars of the present invention is such that the spiral reinforcing bars are attached in a positioned state by binding the base ends and tips of the diagonal connecting bars to the base ends or tip ends of each of the adjacent joint reinforcing bars that protrude alternately in a staggered manner.

[0016] Furthermore, in the reinforcement structure of the joint portion using the spiral reinforcing bar of the present invention, it is preferable that the spiral reinforcing bar and the joint reinforcing bar are connected by binding them with binding wire. [Effects of the Invention]

[0017] According to the reinforcement structure of the joint section using spiral reinforcing bars of the present invention, it is possible to smoothly position and arrange reinforcement at the joint section between a pair of adjacent concrete slabs, preferably made of precast PC deck slabs, and by expanding the range over which the restraining effect of the concrete extends, it is possible to omit the straight connecting main reinforcements that connect the joint reinforcing bars to each other.By using spiral reinforcing bars, it is possible to easily obtain a reinforcement structure of the joint section that can be reinforced to ensure the necessary strength when forming the joint section of a precast deck slab, and it is also possible to improve workability when pouring concrete. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of a spiral reinforcing bar for a joint portion used in a reinforcement structure for a joint portion according to a preferred embodiment of the present invention. FIG. [Figure 2] 1 from the Z direction, and FIG. 1(b) is a side view of FIG. 1 from the Y direction. [Figure 3] FIG. 2 is a front view of FIG. 1 as seen from the X direction, which is the axial direction of the spiral. [Figure 4] 1(a) to 1(c) are perspective views illustrating a reinforcement structure of a joint using a spiral reinforcing bar according to a preferred embodiment of the present invention. [Figure 5] (a) is a cross-sectional view of a key part illustrating joint reinforcing bars that each protrude from the end face of a concrete slab, and (b) is a cross-sectional view of a key part illustrating the reinforcement structure using the joint reinforcing bars of (a). [Figure 6] (a) is a cross-sectional view of a key part illustrating other joint reinforcing bars each protruding from the end face of a concrete slab, and (b) is a cross-sectional view of a key part illustrating the reinforcement structure using the other joint reinforcing bars of (a). [Figure 7] (a) to (c) are schematic plan views illustrating the state in which a spiral reinforcing bar for a joint section is bound to a joint reinforcing bar, and (b) is a schematic plan view explaining the reinforcement structure of a joint section using a spiral reinforcing bar according to a preferred embodiment of the present invention. [Figure 8] FIG. 10 is a simplified perspective view illustrating a joint between multiple precast PC deck slabs installed in series. DETAILED DESCRIPTION OF THE INVENTION

[0019] A joint reinforcement structure 15 using a spiral reinforcing bar according to a preferred embodiment of the present invention, shown in Figure 7(b), is formed using the spiral reinforcing bar 10 for a joint shown in Figure 1. For example, in repair work on an existing road bridge, when replacing an aging concrete deck with a precast PC deck 20, preferably made of precast concrete, the spiral reinforcing bar 10 is arranged in each of a plurality of joints 22 of the precast PC deck 20, which are installed in a continuous manner in the bridge axis direction, as shown in Figure 8, and is used as reinforcing bar for forming reinforcement structures 15, 15' (see Figures 4(a) to (c)) of the joints 22 together with joint reinforcing bars 21 protruding from the end faces 20a of the precast PC deck 20, prior to pouring concrete into the joints 22. The spiral reinforcing bars 10 for the joints enable smooth positioning and reinforcement at the joints 22 between a pair of adjacent precast PC deck slabs 20, and also have the function of expanding the range over which the restraining effect of the concrete extends, thereby making it possible to omit the linear connecting main reinforcements that connect the joint reinforcing bars 21 to each other.

[0020] In this embodiment, the spiral reinforcing bar 10 for the joint section is arranged in the concrete pouring space of the joint section 22 between a pair of adjacent concrete slabs, preferably a pair of adjacent precast PC deck slabs 20, as shown in Figures 1 to 4, and together with the joint reinforcing bars 21 protruding from the end faces 20a of the precast PC deck slabs 20 on both sides facing each other in this pouring space, forms a reinforcement structure 15 in the joint section 22. The spiral reinforcing bar 10 for the joint section has a spiral shape in which a plurality of unit spiral reinforcing bars 11, each having a rectangular front view (see Figure 3), are connected at a predetermined pitch in the spiral axial direction X by bending a single reinforcing bar (see Figures 1, 2(a), and (b)). Each continuous unit spiral reinforcing bar 11 has a pair of short side portions 11a and 11b, which are the left and right vertical side portions of the rectangular front view, and a long side portion 11c, which is one horizontal side portion, arranged along an imaginary base plane P (see Figures 2(a) and (b)), and the other horizontal side portion, the long side portion 11d, is an oblique connecting bar that extends in an inclined direction at an angle θ of 10 to 35 degrees, more preferably 10 to 20 degrees (see Figure 2(a)), relative to the imaginary base plane P on which these three side portions are arranged, when viewed from above. As a result, the unit spiral reinforcing bar has a Z-spiral shape in which Z shapes are continuous when viewed from above.

[0021] In addition, in this embodiment, the joint reinforcing bars 21 protruding from the end face 20a of each of the precast PC deck slabs 20 on both sides are arranged in two stages, including upper reinforcing bars 21a and lower reinforcing bars 21b, as shown in Figure 5(a), and the joint reinforcing bars 21 protruding from the end face 20a of one precast PC deck slab 20 and the joint reinforcing bars 21 protruding from the end face 20a of the other precast PC deck slab 20 are arranged alternately in a staggered pattern in the longitudinal direction X of the joint portion 22 (see Figure 7(a)).The three side portions 11a, 11b, and 11c arranged on the imaginary base surface P are arranged in the spaces between the alternately arranged joint reinforcing bars 21, and the diagonal connecting bars 11d of the other long side portion are arranged so as to intersect with the upper reinforcing bars 21a, so that the joint portion 22 can be arranged in a state where reinforcement is provided.

[0022] Furthermore, in this embodiment, the joint reinforcing bar 21 is preferably a loop reinforcing bar in which the end of the upper reinforcing bar 21a and the end of the lower reinforcing bar 21b are connected via an arc-shaped portion 21c (see Figure 5(a)).

[0023] In this embodiment, the spiral reinforcing bar 10 for the joint is a deformed reinforcing bar with a diameter of, for example, about 10 mm. Using a special reinforcing bar bending machine, it can be easily bent into a spiral shape from a single reinforcing bar. As shown in FIGS. 1 and 2(a) and (b), the spiral reinforcing bar 10 has a spiral shape in which multiple unit spiral reinforcing bars 11, each having a rectangular front view, are connected in the spiral axial direction X at a predetermined pitch s (half the pitch of the joint reinforcing bars 21 protruding from either end surface 20a of one or the other precast PC deck slab 20), for example, about 62.5 mm. The imaginary base plane P on which the pair of left and right short side portions 11a, 11b and one long side portion 11c of the unit spiral reinforcing bar 11 are arranged is preferably perpendicular to the spiral axial direction X.

[0024] Furthermore, in this embodiment, when the thickness of the precast PC deck 20 is, for example, about 220 mm and the width of the joint portion 22 is about 280 mm, each unit spiral reinforcing bar 11, when viewed from the front from outside the axial direction X of the spiral, has a horizontally elongated rectangular frame shape, as shown in Figure 3, with the short side portions 11a, 11b, which are the vertical side portions on both the left and right sides, having a length (height) of, for example, about 120 mm, and the long side portions 11c, 11d, which are the horizontal side portions on the top and bottom, having a length of, for example, about 230 mm, and the four corner portions are curved so that the inner radius of curvature is, for example, about R25. The other long side portion, the upper long side portion 11d, is an oblique connecting reinforcement that extends in a direction inclined at an angle θ of, for example, about 15 degrees when viewed from above relative to the imaginary base plane P on which the pair of left and right short side portions 11a, 11b and one long side portion 11c are arranged (see Figure 2(a)), and has a length of, for example, about 240 mm when viewed from above.

[0025] If the spiral reinforcing bar 10 for the joint section cannot be formed from only one reinforcing bar to have a length equivalent to the extension of the joint section 22, multiple spiral reinforcing bars 10 can be formed from multiple reinforcing bars, and the ends can be overlapped and tied together as a lap portion, for example, to connect them together in the axial direction X of the spiral, thereby forming a spiral reinforcing bar 10 for the joint section with a length equivalent to the extension of the joint section 22.

[0026] On the other hand, in this embodiment, the joint rebars 21 are loop rebars in which the ends of the upper rebars 21a and the lower rebars 21b are connected via the arc-shaped portions 21c, as described above. The joint rebars 21 protruding from the end face 20a of one precast PC deck 20 and the joint rebars 21 protruding from the end face 20a of the other precast PC deck 20 are alternately arranged in a staggered pattern in the longitudinal direction X of the joint portion 22, which is the axial direction X of the spiral of the spiral rebar 10 for the joint portion, as shown in FIG. 7(a). The upper rebars 21a and lower rebars 21b of these joint rebars 21, which are loop rebars, are preferably arranged so as to protrude perpendicularly from the end face 20a of the precast PC deck 20, which is a concrete slab, when viewed from above.

[0027] 7(a), the spiral reinforcing bar 10 for the joint has three sides, consisting of a pair of left and right short side portions 11a, 11b and one long side portion 11c, arranged on an imaginary base plane P, which are preferably arranged at intervals between joint reinforcing bars 21, preferably loop reinforcing bars, which are alternately arranged at a predetermined pitch s', similar to the pitch s of the unit spiral reinforcing bars 11 of the spiral reinforcing bar 10, and the diagonal connecting bar of the other long side portion 11d is arranged so as to intersect with the upper reinforcing bar 21a of the joint reinforcing bar 21, and then tied together with, for example, a binding wire 12, to form reinforcement in the joint 22. This makes it easy to form the reinforcement structure 15 for the joint together with the joint reinforcing bars 21, preferably loop reinforcing bars, which are alternately arranged.

[0028] That is, in this embodiment, the joint portion reinforcement structure 15, 15' is a reinforcement structure using spiral reinforcing bars 10 provided in the concrete pouring space of the joint portion 22 between a pair of adjacent concrete slabs, preferably a pair of precast PC floor slabs 20, and the joint reinforcing bars 21 protrude from the end faces of the precast PC floor slabs 20 on both sides facing each other in the concrete pouring space of the joint portion 22, and the joint reinforcing bars 21 are arranged in a state where a plurality of joint reinforcing bars 21 protruding from the end face 20a of one precast PC floor slab 20 and a plurality of joint reinforcing bars 21 protruding from the end face 20a of the other precast PC floor slab 20 are alternately arranged in a staggered pattern in the longitudinal direction X of the joint portion, and the joint reinforcing bars 21 are loop-shaped reinforcing bars in which the ends of the upper reinforcing bars 21a and the ends of the lower reinforcing bars 21b arranged in two stages above and below are connected via arc-shaped portions 21c, and the joint reinforcing bars 21 are arranged on the imaginary base surface P of the spiral reinforcing bars 10. The spiral reinforcing bar 10 is attached to the joint portion 22 in such a state that the three side portions 11a, 11b, and 11c of each unit spiral reinforcing bar 11 are arranged in the spaces between the alternately arranged joint reinforcing bars 21, and the diagonal connecting bars 11d are arranged so as to intersect with the upper reinforcing bars 21a of the joint reinforcing bars 21. When the attached spiral reinforcing bar 10 is projected from the outside in the axial direction X, a loop-shaped joint reinforcing bar protruding from the end face 20a of one of the precast PC deck slabs 20 is The area where the spiral reinforcing bar 10 and the loop-shaped joint reinforcing bar 21 protruding from the end face 20a of the other precast PC deck 20 overlap is surrounded by a rectangular frame shape of the unit spiral reinforcing bars 11, as shown in Figure 5(b), and the attached spiral reinforcing bar 10 and joint reinforcing bar 21 are connected by binding, preferably, with binding wires 12 (see Figure 7), and are installed in the concrete pouring space of the joint part 22. The connection between the spiral reinforcing bar 10 and the joint reinforcing bar 21 can be achieved by binding with binding wires 12, as well as by various other connecting means such as clips and spacers.

[0029] As a result, in this embodiment, by smoothly positioning and arranging the spiral reinforcing bars 10 at the joint between a pair of adjacent precast PC decks 20, it is possible to easily form the joint reinforcement structure 15, 15' together with the joint reinforcing bars 21, and by expanding the range over which the concrete restraint effect extends, it is possible to omit the linear connecting main reinforcing bars that connect the joint reinforcing bars 21 to each other. This also makes it possible to effectively prevent the thickness of the precast PC deck slab 20 from becoming thicker than necessary.

[0030] Here, when the installed spiral reinforcing bar 10 is projected from the outside in the axial direction X, the positional relationship in which the area where the loop-shaped joint reinforcing bar 21 protruding from the end face 20a of one precast PC deck 20 and the loop-shaped joint reinforcing bar 21 protruding from the end face 20a of the other precast PC deck 20 overlap is surrounded by a rectangular frame shape made up of the unit spiral reinforcing bar 11 can preferably be a positional relationship in which the inner space portion surrounded by these reinforcing bars in the area where the loop-shaped joint reinforcing bar 21 of one precast PC deck 20 and the loop-shaped joint reinforcing bar 21 of the other precast PC deck 20 overlap is surrounded by the inner edge of the reinforcing bars arranged in a rectangular frame shape made up of the unit spiral reinforcing bar 11 of the spiral reinforcing bar 10.

[0031] In addition, in a reinforcement structure 15 of a joint section using spiral reinforcing bars according to a preferred embodiment of the present invention, as shown in Figure 7(b), the spiral reinforcing bar 10 for the joint section has three side portions 11a, 11b, and 11c arranged on the virtual base surface P of the unit spiral reinforcing bar 11 arranged in the gaps between the alternately arranged joint reinforcing bars 21, and the diagonal connecting bar 11d is arranged so as to intersect with the upper reinforcing bar 21a of the joint reinforcing bar 21, and the three side portions 11a, 11b, and 11c arranged on the virtual base surface P are positioned close to or in contact with one of the joint reinforcing bars 21 on both sides of the gap, and the spiral reinforcing bar 10 and the joint reinforcing bar 21 are tied together using a tie wire 12, thereby attaching the spiral reinforcing bar 10 to the joint reinforcing bar 21, so that the spiral reinforcing bar 10 is attached to the concrete pouring space of the joint section 22.

[0032] In the reinforcement structure 15 of the joint section using the spiral reinforcing bars of this embodiment, the spiral reinforcing bars 10 are attached in a positioned state, preferably by tying the base end and tip end of the diagonal connecting bars 11d to the base end side or tip end side of each of the adjacent joint reinforcing bars 21 that protrude alternately in a staggered manner.

[0033] As a result, according to the reinforcement structure 15 of the joint section using the spiral reinforcing bars of this embodiment, the reinforcing bars arranged to cross the gaps between the joint reinforcing bars 21 when viewed from above are generally only the diagonal connecting bars 11d, and the space into which a vibrator can be inserted is increased, making it possible to efficiently compact the concrete poured into the joint section 22 in a later process, thereby improving the ease of construction when pouring the concrete.

[0034] When the spiral reinforcing bar 10 and the joint reinforcing bar 21 are fastened together with the three side portions 11a, 11b, and 11c arranged on the imaginary base plane P biased toward one of the joint reinforcing bars 21 on either side of the gap, as described above, it is preferable to fasten the base end and tip end of the diagonal connecting bar 11d to the base end or tip end of each of the adjacent joint reinforcing bars 21 that protrude alternately, thereby making it possible to install the spiral reinforcing bar 10 in a positioned state.

[0035] Furthermore, as shown in Figure 7(c), the three-sided spiral reinforcing bar 10 for a joint can be arranged on a virtual base plane P, with the pair of left and right short side portions 11a, 11b and one long side portion 11c, alternately positioned at the intervals between the splice reinforcing bars 21, preferably loop reinforcing bars. In this case, the pitch s of the unit spiral reinforcing bars 11 is 125 mm, which is twice the pitch s' at which the splice reinforcing bars 21 are alternately positioned. The diagonal connecting bar formed by the other long side portion 11d extends in a direction inclined at an angle θ of 28.5 degrees relative to the virtual base plane P when viewed from above. The diagonal connecting bar formed by the one long side portion 11c positioned above is tied to the splice reinforcing bars 21 where the three-sided portions formed by the pair of left and right short side portions 11a, 11b and one long side portion 11c are not positioned off-center. In this case, the amount of reinforcing bar in the spiral reinforcing bar 10 for the joint portion is reduced, so the length formed from one reinforcing bar can be increased, and preferably the number of points tied together by tie bars can be reduced.

[0036] In this embodiment, the joint reinforcing bars 21 protruding from each end face 20a of a pair of precast PC deck slabs 20 do not necessarily have to be loop reinforcing bars in which the end of the upper reinforcing bar 21a and the end of the lower reinforcing bar 21b are connected via an arc-shaped portion 21c, and can also be two-tiered reinforcing bars, for example, as shown in Figure 6(a), consisting of a straight-shaped upper reinforcing bar 21d arranged in the upper tier and a hook-shaped lower reinforcing bar 21e arranged in the lower tier, with the tip of the straight portion curved in a hook shape.

[0037] In this case, the reinforcement structure 15' of the joint portion is arranged such that the three side portions 11a, 11b, 11c arranged on the virtual base surface P of the unit spiral reinforcing bar 11 of the spiral reinforcing bar 10 are arranged in the intervals of the joint reinforcing bar 21' which is a two-stage arrangement of straight upper reinforcing bars 21d and hooked lower reinforcing bars 21e arranged alternately (see Figures 7(a) and (b)), and the diagonal connecting bars 11d are arranged so as to intersect with the straight upper reinforcing bars 21d of the joint reinforcing bars 21', and are arranged When viewed from outside in the axial direction X of the spiral reinforcing bar 10, as shown in Figure 6(b), the area surrounded by the lower reinforcing bars 21e on both the left and right sides made of hook reinforcement and the straight-shaped upper reinforcing bar 21d is further surrounded by the rectangular frame shape of the unit spiral reinforcing bar 11, and by tying the spiral reinforcing bar 10 and the joint reinforcing bar 21' using a tie wire 12, the spiral reinforcing bar 10 can be installed in the concrete pouring space of the joint part 22.

[0038] In this embodiment, the joint reinforcing bars that protrude from the end surface 20a of the precast PC deck 20 that constitutes the reinforcement structure of the joint portion into the concrete pouring space of the joint portion 22 do not have to be the loop reinforcing bars or those that consist of the straight upper reinforcing bars 21d and the hooked lower reinforcing bars 21e described above. The joint reinforcing bars may be reinforcing bars in which the upper reinforcing bars 21d are hooked and the lower reinforcing bars 21e are straight, or the upper and lower reinforcing bars of the two-stage reinforcement arrangement may both be straight reinforcing bars (not shown).

[0039] Furthermore, the joint section to which the spiral reinforcing bars 10 are attached and the reinforcement structure of the joint section is established does not necessarily have to be the joint section 22 between multiple precast PC deck slabs 20 installed in a continuous line in the bridge axis direction, but may also be, for example, the joint section between a pair of adjacent concrete slabs formed by cast-in-place concrete.

[0040] Therefore, in this embodiment, the reinforcement structures 15, 15' of the joint portion are This is a reinforcement structure using spiral reinforcing bars (10) installed in the concrete pouring space of the joint between the cleat slabs. The joint reinforcing bars protrude from the end faces of the concrete slabs on both sides facing each other in the concrete pouring space of the joint, and are arranged in two stages, including upper and lower reinforcing bars. The joint reinforcing bars protruding from the end face of one concrete slab and the joint reinforcing bars protruding from the end face of the other concrete slab are arranged in a staggered pattern along the length of the joint. The three side portions (11a, 11b, 11c) of the spiral reinforcing bar (10) arranged on the imaginary base surface (P) are arranged in the spaces between the alternately arranged joint reinforcing bars, and the diagonal connecting bar (11d) is arranged so as to intersect with the upper reinforcing bars of the joint reinforcing bars. The spiral reinforcing bar (10) is attached to the joint section (22). The attached spiral reinforcing bar (10) and the joint reinforcing bar are tied together using tie wires (12), so that the spiral reinforcing bar can be installed in the concrete pouring space of the joint section. This makes it possible to easily obtain a reinforcement structure for the joint portion that can be reinforced to ensure the required strength.

[0041] The present invention is not limited to the above-described embodiment and various modifications are possible. For example, the rectangular front shape of a unit spiral reinforcing bar for a joint, which consists of a pair of vertical sides and a pair of horizontal sides, does not necessarily have to be a horizontally elongated frame shape with the vertical sides as short sides and the horizontal sides as long sides. For example, the horizontally elongated frame shape can include a horizontally elongated oval shape with the short sides curved in an arc. Even if the short sides are curved in a horizontally elongated oval shape, the same effects can be achieved. The inclination angle of the diagonal continuous reinforcing bars (diagonal connecting reinforcing bars), which are preferably extended in a direction inclined at an angle of 10 to 35 degrees when viewed from above, can be either a right-hand or left-hand oblique angle, and the spiral shape, which has a continuous Z-shape when viewed from above, can be an inverted Z pattern. [Explanation of symbols]

[0042] 10 Spiral reinforcing bars for joints 11 units spiral rebar 11a, 11b Short side part (vertical side part) 11c One long side (horizontal side) 11d Diagonal connecting bars (one long side, horizontal side) 12 Binding wire 15,15' Reinforcement structure 20 Precast PC deck 20a end face 21,21' Reinforced concrete joint 21a Upper reinforcing bar 21b Bottom rebar 21c Arc-shaped part 21d Straight top rebar 21e Bottom reinforcement with hook bars 22 Joint P Virtual base plane θ Angle between the diagonal connecting bar and the virtual base surface when viewed from above s unit spiral rebar pitch s' Pitch of joint rebar X Spiral axial direction (longitudinal direction of joint)

Claims

1. A reinforcement structure using spiral reinforcing bars provided in the concrete pouring space of the joint between a pair of adjacent concrete slabs, The spiral rebar is formed by bending a single rebar, so that a plurality of unit spiral rebars each having a rectangular front view have a spiral shape that continues at a predetermined pitch in the axial direction of the spiral, and each of the continuous unit spiral rebars has a pair of left and right short side portions and one long side portion of the rectangular front view that are arranged on an imaginary reference plane, and the other long side portion is an oblique connecting rebar that extends in a direction inclined at 10 to 35 degrees when viewed from above relative to the imaginary reference plane on which these three side portions are arranged, thereby forming a Z-spiral shape with a continuous Z shape when viewed from above, The joint reinforcing bars protrude from the end faces of the concrete slabs on both sides facing each other in the concrete pouring space of the joint portion, and are arranged in two stages including upper reinforcing bars and lower reinforcing bars, and the joint reinforcing bars protruding from one end face of the concrete slab and the joint reinforcing bars protruding from the other end face of the concrete slab are arranged in a staggered pattern alternately in the length direction of the joint portion, The three sides of the spiral reinforcing bar arranged on the virtual reference plane are alternately arranged. A reinforcement structure of a joint section using a spiral reinforcing bar in which the spiral reinforcing bar is attached in the concrete pouring space of the joint section by connecting the spiral reinforcing bar and the joint reinforcing bar with the three side portions arranged on the virtual reference plane in close proximity to or in contact with one of the joint reinforcing bars on both sides of the gap and biasing them to one side.

2. A reinforcement structure of a joint section using spiral reinforcement as described in claim 1, wherein the virtual base plane is a plane perpendicular to the axial direction of the spiral, and the upper reinforcement and the lower reinforcement of the joint reinforcement protrude in a direction perpendicular to the end face of the concrete slab when viewed from above.

3. A reinforcement structure for a joint using spiral steel bars as described in claim 1 or 2, wherein the joint between a pair of adjacent concrete slabs is a joint formed between a pair of adjacently installed precast PC deck slabs.

4. A reinforcement structure of a joint section using spiral reinforcement as described in claim 1 or 2, wherein the three side portions arranged on the virtual base plane are arranged alternately in the spaces between the alternately arranged joint reinforcement bars.

5. A reinforcement structure of a joint section using spiral reinforcing bars as described in claim 1 or 2, wherein the joint reinforcing bars are loop reinforcing bars in which the ends of the upper reinforcing bars and the lower reinforcing bars are connected via an arc-shaped portion.

6. A reinforcement structure of a joint section using spiral reinforcing bars as described in claim 1 or 2, in which the spiral reinforcing bars are attached in a positioned state by tying the base end and tip end of the diagonal connecting bars to the base end side or tip end side of each of the adjacent joint reinforcing bars that protrude alternately.

7. 3. A reinforcement structure for a joint using a spiral reinforcing bar according to claim 1 or 2, wherein the spiral reinforcing bar and the joint reinforcing bar are connected by binding them with a binding wire.

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