Joint part bar arrangement structure with use of spiral reinforcement bar

Abstract

To enable an easy construction of a joint part bar arrangement structure that can be reinforced to secure required strength.SOLUTION: Joint reinforcement bars 21 are constituted by a double-stage bar arrangement that comprises straight-shaped upper reinforcement bars 21d located in the upper level and hook-shaped lower reinforcement bars 21e located in the lower level. A joint part bar arrangement structure 15 is placed in a concrete-casting space of a joint part 22 with such arrangements that the three side parts 11a, 11b, 11c of a spiral reinforcement bar 10, which are positioned on the imaginary base surface P, are placed in the interval portions of the alternately-arranged joint reinforcement bars 21 constituted by the double-stage bar arrangement; diagonal linkage bars 11d are arranged crossing the upper reinforcement bars 21d of the joint reinforcement bars 21; and the spiral reinforcement bar 10 and the joint reinforcement bars 21 are bound in a positional relation in which, in a projection view from the outside along the axial direction X of the placed spiral reinforcement bar 10, the area surrounded with the hook-shaped lower reinforcement bars 21e on the right and left sides and the straight-shaped upper reinforcement bar 21d is further surrounded with the rectangular-shaped frame form using the spiral reinforcement bar 10.SELECTED DRAWING: Figure 4

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 projects involving concrete deck replacement, rectangular precast PC decks made of precast concrete are commonly used to reduce construction labor and shorten construction periods. In renovation projects using precast PC decks, for example, existing road bridges, the 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 decks, which form the main body of the road, are supported by multiple girders installed at predetermined intervals in a direction perpendicular to the bridge axis direction, with their long sides preferably aligned perpendicularly to the girders. The precast PC decks are 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 in the designated position in the ring-shaped portion require a special overhanging scaffolding to be set up on the side of the bridge girder, and the work of holding long, straight reinforcing bars from the overhanging scaffolding to insert 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 in 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 in Patent Document 1, the spiral reinforcing bar has a constant angle of helix with respect to the central axis and has a circular front shape when viewed from the outside in the axial direction (lengthwise), which makes it time-consuming to position it on-site when arranging the reinforcement at the joint, and the range of the concrete restraint effect of the spiral reinforcing bar is limited to the circular area inside the annular part where the alternately arranged joint reinforcing bars, such as loop joint reinforcing bars, overlap, making it impossible to omit the linear connecting main reinforcing bars arranged, for example, outside the annular part where the loop joint reinforcing bars overlap.In addition, when forming joints in precast decks using spiral reinforcing bars, it is desirable to easily obtain a reinforcement structure for the joint that can be reinforced to ensure the necessary strength.

[0009] Furthermore, for example, when precast PC deck slabs are used in road bridges, bending moments with the piers or abutments as supports act on the joints, which can cause bias in the vertical stress distribution of the joints and lead to the risk of the joints being damaged. In such cases, it is desirable for the reinforcement structure of the joints to be designed so that the rigidity of the joints can be changed according to the vertical stress distribution, effectively preventing damage due to bending moments acting on the joints.

[0010] The present invention aims to provide a reinforcement structure for a joint using spiral reinforcing bars that allows spiral reinforcing bars to be smoothly positioned and arranged at the joint between a pair of adjacent concrete slabs, preferably precast PC deck slabs, and that allows the linear connecting main reinforcements that connect the joint reinforcing bars to each other to be omitted by expanding the range over which the restraining effect of the concrete extends, and that allows for easy construction of a reinforcement structure for a joint that can be reinforced to ensure the necessary strength when forming a joint in a precast deck using spiral reinforcing bars. [Means for solving the problem]

[0011] The present invention is a reinforcement structure of a joint using a spiral reinforcing bar, which is provided in a concrete pouring space of a joint between a pair of adjacent concrete slabs, and the spiral reinforcing bar has a spiral shape in which a plurality of unit spiral reinforcing bars having a rectangular front view are connected at a predetermined pitch in the axial direction of the spiral by bending a single reinforcing bar, and each of the continuous unit spiral reinforcing bars has a pair of left and right vertical side portions and one horizontal side portion of the rectangular front view shape arranged on an imaginary base surface, and the other horizontal side portion is an oblique connecting bar extending in a direction inclined at an angle of 10 to 35 degrees in top view with respect to the imaginary base surface on which these three side portions are arranged, thereby having a Z spiral shape with a continuous Z shape in top view, and joint reinforcing bars protruding from the end faces of the concrete slabs on both sides facing each other in the concrete pouring space of the joint, and the joint reinforcing bars are connected to each other in a Z spiral shape with a plurality of joint reinforcing bars protruding from one end face of the concrete slab and a plurality of joint reinforcing bars protruding from the other end face of the concrete slab. The spiral reinforcing bars are arranged in a staggered pattern in the length direction of the joint, and the joint reinforcing bars are two-tiered reinforcing bars consisting of an upper reinforcing bar with a straight shape arranged in the upper tier and a lower reinforcing bar with a hook reinforcing bar whose tip is curved in a hook shape arranged in the lower tier. The three side portions arranged on the virtual base surface of the spiral reinforcing bar 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. The above-mentioned object has been achieved by providing a reinforcement structure for a joint section using a spiral reinforcing bar that is installed in the concrete pouring space of the joint section, by connecting the spiral reinforcing bar and the joint reinforcing bar in a position where, when projected from outside the axial direction of the installed and arranged spiral reinforcing bar, the area surrounded by the lower reinforcing bars on both the left and right sides made of hook reinforcements and the straight-shaped upper reinforcing bar is further surrounded by a rectangular frame shape made of the unit spiral reinforcing bars.

[0012] Furthermore, it is preferable that the reinforcement structure of the joint using the spiral reinforcing bar of the present invention is such that the lower reinforcing bar made of hook reinforcing bar is made of 135° hook reinforcing bar, whose tip is curved in a hook shape within an angle range of 135°.

[0013] In addition, 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 be a surface 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.

[0014] 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.

[0015] Furthermore, in the reinforcement structure of the joint section using the spiral steel bars of the present invention, it is preferable that the joint section between a pair of adjacent concrete slabs is a joint section between a pair of adjacently installed precast PC deck slabs.

[0016] In addition, 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 the spiral reinforcing bars of the present invention, reinforcement can be smoothly positioned and arranged at the joint section between a pair of adjacent concrete slabs, and by expanding the range over which the restraining effect of the concrete extends, it is possible to omit the linear connecting main reinforcements that connect the joint reinforcing bars to each other, and it is possible to effectively avoid damage to the joint section due to bending moments acting on the joint section. [Brief explanation of the drawings]

[0018] [Figure 1]FIG. 1 is a perspective view of a spiral reinforcing bar used in a reinforcement structure of a joint according to a preferred embodiment of the present invention. [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 for a joint using a spiral reinforcing bar for a joint 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] 1(a) to 1(c) are schematic plan views illustrating a state in which a spiral reinforcing bar used in a reinforcement structure for a joint according to a preferred embodiment of the present invention is bound to a joint reinforcing bar. [Figure 7] 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 reinforcement structure for a joint using a spiral reinforcing bar according to a preferred embodiment of the present invention, as shown in Fig. 1, is a reinforcement structure in which, for example, a spiral reinforcing bar for a joint is arranged at the joint. For example, in repair work on an existing road bridge, when replacing an aging concrete slab with a precast PC slab 20, preferably made of precast concrete, the spiral reinforcing bar for a joint 10 shown in Fig. 1 is arranged at each of a plurality of joints 22 of the precast PC slabs 20, which are installed in a continuous manner in the bridge axis direction as shown in Fig. 7, and is used as reinforcing bars for forming a reinforcement structure 15 (see Figs. 4(a) to (c)) for the joints 22 together with the joint reinforcing bars 21 protruding from the end faces 20a of the precast PC slabs 20, prior to pouring concrete into the joints 22. The reinforcement structure of the joint section using the spiral reinforcement bar 10 for the joint section of this embodiment allows for smooth positioning and reinforcement at the joint section 22 between a pair of adjacent precast PC deck slabs 20, and by expanding the range over which the restraining effect of the concrete extends, it is possible to omit the straight connecting main reinforcement that connects the joint reinforcement bars 21 to each other, and it has the function of effectively avoiding damage to the joint section 22 due to bending moments acting on the joint section 22.

[0020] The spiral reinforcing bar 10 for the joint section used in the reinforcement structure of the joint section of this embodiment is arranged in the concrete pouring space of the joint section 22 between a pair of adjacent concrete slabs, preferably a pair of precast PC deck slabs 20 installed adjacently, as shown in Figures 1 to 4, and together with the joint reinforcing bars 21 each protruding from the end faces 20a of the precast PC deck slabs 20 on both sides facing each other in this pouring space, it is a spiral-shaped reinforcing bar that forms the reinforcement structure 15 at the joint section 22. The spiral reinforcing bar 10 for joints in this embodiment has a spiral shape in which a plurality of unit spiral reinforcing bars 11 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)), when viewed from above, relative to the imaginary base plane P on which these three side portions are arranged, thereby forming 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 21d and lower reinforcing bars 21e, 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 6(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 21d, 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 a two-tiered reinforcing bar consisting of an upper reinforcing bar 21d with a straight shape arranged in the upper tier and a lower reinforcing bar 21e with a hook reinforcing bar whose tip is curved in a hook shape in the straight part arranged in the lower tier (see Figure 5(a)).

[0023] 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 between the joint reinforcing bars 21 of the two-stage reinforcement arrangement consisting of the straight-shaped upper reinforcing bars 21d arranged alternately and the hook-shaped lower reinforcing bars 21e (see Figures 6(a) and (b)), and the diagonal connecting bars 11d are arranged so as to intersect with the straight-shaped upper reinforcing bars 21d of the joint reinforcing bars 21, and the arranged When viewed from outside the axial direction X of the spiral reinforcing bar 10, as shown in Figure 5(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 together using a tie wire 12, the spiral reinforcing bar 10 can be installed in the concrete pouring space of the joint part 22.

[0024] In this way, joint reinforcing bar 21 is a reinforcing bar with two independent tiers of reinforcing bars, with straight upper reinforcing bar 21d arranged in the upper tier and lower reinforcing bar 21e arranged in the lower tier and made of hook reinforcing bars with hook-shaped curved ends at the ends of the straight portions. Therefore, for example, if a bending moment acts on joint part 22 and causes a bias in the stress distribution in the vertical direction of joint part 22, it is possible to set different rigidities independently for each reinforcing bar by changing the diameter of each reinforcing bar according to the stress distribution, and it is possible to effectively avoid damage to joint part 22 due to the bending moment acting on joint part 22.

[0025] The lower reinforcing bar 21e made of hook reinforcement is a 135° hook reinforcement whose tip is curved in a hook shape within an angle range of 135°.

[0026] In this embodiment, the spiral reinforcing bar 10 for a 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 for a joint 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 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.

[0027] 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, the upper long side 11d, acts as a diagonal connecting reinforcement and extends at an angle θ of, for example, 15.2 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)), resulting in a length of, for example, about 240 mm when viewed from above. The length of these unit spiral reinforcing bars 11 can be changed as appropriate depending on the designed thickness of the precast PC deck 20, the width of the joint portion 22, etc.

[0028] If the spiral reinforcing bar 10 for the joint section cannot be formed from only one reinforcing bar to ensure a length equivalent to the extension of the joint section 22, multiple spiral reinforcing bars 10 for the joint section 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.

[0029] On the other hand, in this embodiment, the joint reinforcing bars 21 are two-tiered reinforcing bars, as described above, consisting of straight upper reinforcing bars arranged in the upper tier and lower reinforcing bars arranged in the lower tier, which are hook reinforcing bars with hook-shaped curves at the ends of the straight sections.Furthermore, the joint reinforcing bars 21 protruding from the end face 20a of one precast PC deck 20 and the joint reinforcing bars 21 protruding from the end face 20a of the other precast PC deck 20 are arranged alternately in a staggered pattern in the length direction X of the joint section 22, which is the axial direction X of the spiral of the joint section spiral reinforcing bar 10 to be arranged, as shown in Figure 6(a), preferably at a predetermined pitch s' similar to the pitch s of the unit spiral reinforcing bars 11 of the joint section spiral reinforcing bar 10. Furthermore, the upper reinforcing bars 21d and lower reinforcing bars 21e of these joint reinforcing bars 21, which are two-stage reinforcing bars, are arranged to protrude in a direction perpendicular to the end surface 20a of the precast PC deck slab 20, which is preferably a concrete slab, when viewed from above.

[0030] 6(a), the spiral reinforcing bar 10 for a joint of this embodiment 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, arranged in the spaces between the joint reinforcing bars 21, preferably made of two-tiered reinforcing bars, which are alternately arranged at a predetermined pitch s', preferably the same as the pitch s of the unit spiral reinforcing bars 11 of the spiral reinforcing bar 10 for a joint, and the diagonal connecting bars of the other long side portion 11d are arranged so as to intersect with the upper reinforcing bars 21d of the joint reinforcing bars 21, and then tied together with, for example, a tie wire 12, to form reinforcement in the joint 22. This makes it easy to form the reinforcing bar arrangement structure 15 for the joint together with the joint reinforcing bars 21, preferably made of loop reinforcing bars, which are alternately arranged.

[0031] That is, in this embodiment, the reinforcing bar structure 15 of the joint portion is a reinforcing bar 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 two-tiered reinforcing bars consisting of straight upper reinforcing bars 21d arranged in the upper tier and hook reinforcing bars 21e arranged in the lower tier, with the tip of the straight portion curved in a hook shape, and each of the joint reinforcing bars 21 arranged on the imaginary base surface P of the spiral reinforcing bar 10 The spiral reinforcing bar 10 is attached to the joint portion 22 in a state in which the three side portions 11a, 11b, and 11c of the 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 21d of the joint reinforcing bars 21. When the attached spiral reinforcing bar 10 is projected from the outside in the axial direction X, the joint reinforcing bar 20 is a reinforcing bar of a two-stage reinforcing bar protruding from the end face 20a of one of the precast PC deck slabs 20. 5(b), the area where the spiral reinforcing bar 10 and the joint reinforcing bar 21, which is a reinforcing bar of a two-stage reinforcing bar 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, and the attached spiral reinforcing bar 10 and the joint reinforcing bar 21 are connected by binding, preferably, with binding wires 12 (see FIG. 6), 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.

[0032] As a result, with the spiral reinforcing bar for joint 10 of this embodiment, by smoothly positioning and arranging reinforcement at the joint between a pair of adjacent precast PC decks 20, it becomes possible to easily form the joint reinforcement structure 15 together with the joint reinforcing bars 21, and by expanding the range over which the restraining effect of the concrete extends, it becomes possible to omit the linear connecting main reinforcement that connects the joint reinforcing bars 21 to each other, and it becomes possible to avoid damage to the joint 22 due to bending moments acting on the joint 22. This also makes it possible to effectively prevent the thickness of the precast PC deck slab 20 from becoming thicker than necessary.

[0033] 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 joint reinforcing bar 21 that is the reinforcing bar of the two-stage reinforcing bar protruding from the end face 20a of one precast PC deck 20 and the joint reinforcing bar 21 that is the reinforcing bar of the two-stage reinforcing bar 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 bar 11 can preferably be a positional relationship in which the inner space portion surrounded by these reinforcing bars in the area where the joint reinforcing bar 21 that is the reinforcing bar of the two-stage reinforcing bar of one precast PC deck 20 and the joint reinforcing bar 21 that is the reinforcing bar of the two-stage reinforcing bar of the other precast PC deck 20 overlap is surrounded by the inner edge of the reinforcing bars arranged in a rectangular frame shape by the unit spiral reinforcing bar 11 of the spiral reinforcing bar 10.

[0034] In addition, in this embodiment, as shown in Figure 6(b), the spiral reinforcing bar 10 for the joint section is arranged in the concrete pouring space of the joint section 22 by arranging the three side portions 11a, 11b, and 11c arranged on the virtual base surface P of the unit spiral reinforcing bar 11 in the gaps between the alternately arranged joint reinforcing bars 21, and arranging the diagonal connecting bar 11d so as to intersect with the upper reinforcing bar 21a of the joint reinforcing bar 21, and tying the spiral reinforcing bar 10 and the joint reinforcing bar 21 together using a binding wire 12 in a state where the three side portions 11a, 11b, and 11c arranged on the virtual base surface P are close to or in contact with one of the joint reinforcing bars 21 on both sides of the gaps and are biased to one side, as shown in Figure 6(b).

[0035] As a result, when viewed from above, the reinforcing bars arranged to cross the gaps between the joint reinforcing bars 21 are generally only 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.

[0036] When the spiral reinforcing bar 10 and the joint reinforcing bar 21 are connected 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 portion, the spiral reinforcing bar 10 can be installed in a positioned state, for example, by connecting the base end and tip end of the diagonal connecting bar 11d to the base end side or tip end side of each of the adjacent joint reinforcing bars 21 that protrude alternately.

[0037] As shown in Figure 6(c), the spiral reinforcing bar 10 for a joint can be arranged so that its three sides, consisting of a pair of left and right short side portions 11a, 11b and one long side portion 11c, are placed on a virtual base plane P, alternately at the intervals between the joint 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 joint reinforcing bars 21 are alternately placed. 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 one long side portion 11c placed above is tied to the joint reinforcing bars 21 whose three sides, consisting of a 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.

[0038] 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.

[0039] Therefore, in this embodiment, the reinforcement structure of the joint section is a reinforcement structure using spiral reinforcing bars 10 that is installed in the concrete pouring space of the joint section between a pair of adjacent concrete slabs, and the joint reinforcing bars each protrude from the end faces of the concrete slabs on both sides facing each other in the concrete pouring space of the joint section, and are arranged in two stages of reinforcement including upper reinforcing bars and lower reinforcing bars, with 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 being arranged alternately in a staggered pattern along the length of the joint section, and the three sides of the spiral reinforcing bars 10 arranged on the imaginary base surface P are arranged in the spaces between the alternately arranged joint reinforcing bars, and the spiral reinforcing bars 10 are attached to the joint section 22 in a state where the diagonal connecting bars are arranged so as to intersect with the upper reinforcing bars of the joint reinforcing bars, and the attached spiral reinforcing bars 10 and the joint reinforcing bars are tied together using tie wires 12, so that they can be installed in the concrete pouring space of the joint section.

[0040] The spiral reinforcing bar for joints of the present invention is not limited to the above-described embodiment and can be modified in various ways. For example, the rectangular front shape of a unit spiral reinforcing bar, consisting of a pair of vertical sides and a pair of horizontal sides, does not necessarily have to be a horizontally elongated rectangular frame shape with the vertical sides as short sides and the horizontal sides as long sides. For example, the horizontally elongated rectangular frame shape can include a horizontally elongated oval shape with the short sides curved in an arc. The same effects can be achieved even when the short sides are curved in a horizontally elongated oval shape. 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- 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]

[0041] 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 Reinforcement structure 20 Precast PC deck 20a end face 21 Reinforced concrete joints 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 of a joint using spiral reinforcing bars, which is provided in a concrete pouring space of a joint between a pair of adjacent concrete slabs, The spiral rebar has a spiral shape in which a plurality of unit spiral rebars having a rectangular frontal shape are connected at a predetermined pitch in the axial direction of the spiral by bending a single rebar, and each of the continuous unit spiral rebars has a pair of left and right vertical side portions and one horizontal side portion of the rectangular frontal shape arranged on an imaginary base surface, and the other horizontal side portion is an oblique connecting bar extending in a direction inclined at 10 to 35 degrees when viewed from above relative to the imaginary base surface on which these three side portions are arranged, thereby having a Z-spiral shape with a continuous Z shape when viewed from above, The joint reinforcing bars are arranged so that they protrude from the end faces of the concrete slabs on both sides facing each other in the concrete pouring space of the joint section, 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 alternately arranged in a staggered pattern in the length direction of the joint section, and the joint reinforcing bars are two-tiered reinforcing bars, consisting of straight upper reinforcing bars arranged in the upper section and lower reinforcing bars arranged in the lower section, each of which is a hook reinforcing bar with a hook-shaped curve at the tip of the straight section, The three side portions arranged on the virtual base surface of the spiral reinforcing bar are arranged in the spaces between the alternatingly 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 when projected from outside the axial direction of the arranged spiral reinforcing bar, the area surrounded by the lower reinforcing bars on both the left and right sides made of hook reinforcements and the straight-shaped upper reinforcing bars is further surrounded by a rectangular frame shape made of the unit spiral reinforcing bars, thereby creating a reinforcement structure of a joint section using spiral reinforcing bars installed in the concrete pouring space of the joint section.

2. The lower reinforcing bar is a 135° hook reinforcing bar, whose hook-shaped tip is bent at an angle of 135°. This is a reinforcement structure of a joint using spiral reinforcing bars as described in claim 1.

3. A reinforcement structure of a joint section using spiral reinforcement as described in claim 1 or 2, 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.

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 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 between a pair of adjacently installed precast PC floor slabs.

6. 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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