Bar arrangement structure for joint part using spiral reinforcement

Abstract

To provide an arrangement structure for joint parts capable of smoothly arranging reinforcement bars in a joint part between concrete slabs and avoiding damage to the joint part due to negative bending.SOLUTION: A spiral reinforcement bar 11 is provided in a concrete placing space of a joint part 22 in a state where the cover thickness of an upper part of an upper reinforcement bar 21a is not invaded due to connection of the spiral reinforcement bar 11 to a joint reinforcement bar 21 in a positional relationship where a joint reinforcement bar 21 protruding from an edge face 20a of one precast PC floor slab 20 and a joint reinforcement bar 21 protruding from an edge face 20a of the other precast PC floor slab 20 are alternately arranged in zigzag in a length direction X of the joint part 22, three side parts 11a, 11b, 11c arranged on a virtual base surface P are arranged in gaps between the alternately arranged joint reinforcement bars 21, and a diagonal connection bar 11d which is the other long side part is arranged at the same height position as the upper reinforcement bar 21a of the joint reinforcement bar 21.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a reinforcement structure of a joint section using spiral reinforcing bars, and in particular to a reinforcement structure of a joint section using spiral reinforcing bars that is provided in the concrete pouring space of a joint section extending in a direction intersecting the main girder in the section between each pair of adjacent precast PC deck 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 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 in Patent Document 1, the spiral reinforcing bars have a constant angle of spiral relative to the central axis, and when viewed from the outside in the axial direction (lengthwise), they have a circular front shape. This makes it time-consuming to position them on site when arranging them in the joint, and the range of the concrete restraining effect of the spiral reinforcing bars is limited to the circular area, preferably inside the ring-shaped part, where the alternately arranged joint reinforcing bars, for example, loop joint reinforcing bars, overlap. Therefore, it is no longer possible to omit the straight connecting main reinforcing bars, which are arranged, for example, outside the ring-shaped part where the loop joint reinforcing bars overlap.

[0009] Furthermore, concrete decks made up of multiple precast PC decks are susceptible to negative bending near the piers or abutments, which means that the joints between a pair of precast PC decks installed near the piers or abutments are at risk of damage due to tensile stress caused by bending, especially in the upper part.

[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 made of precast PC deck slabs, and that allows the linear connecting main bars 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 ensures the bending strength and strength of the joint against negative bending, thereby preventing the joint from being damaged by negative bending. [Means for solving the problem]

[0011] The present invention is a reinforcement structure for joints using spiral reinforcing bars, which are provided in the concrete pouring space of joints extending in a direction intersecting with the main girders in the section between each pair of adjacent precast PC deck slabs, and which are supported by a plurality of main girders erected between a pair of abutments and made of a plurality of precast PC deck slabs attached in series in the extension direction of the main girders. The spiral reinforcing bars are provided with a spiral shape in which a plurality of unit spiral reinforcing bars having a rectangular front shape 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 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 forming a Z-spiral shape in which Z shapes are continuous when viewed from above. The above-mentioned object is achieved by providing a reinforcement structure for a joint using a spiral reinforcing bar that is provided in the concrete pouring space of the joint, without eroding the cover thickness above the upper reinforcing bar, wherein 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 a state in which 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 alternately arranged in a staggered pattern in the longitudinal direction of the joint, and the three side portions of the spiral reinforcing bar that are arranged on the imaginary base surface are arranged in the spaces between the alternately arranged joint reinforcing bars, and the diagonal connecting bars of the other horizontal side portion are arranged at the same height as the upper reinforcing bar of the joint reinforcing bar, thereby connecting the spiral reinforcing bar and the joint reinforcing bar.

[0012] Furthermore, in the reinforcement structure of the joint section using the spiral reinforcement of the present invention, it is preferable that the upper reinforcement of the joint reinforcement is arranged at a position lower by the thickness of the diagonal connecting reinforcement.

[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 reinforcing bar of the present invention, it is preferable that the joint reinforcing bar is a loop reinforcing bar in which the end of the upper reinforcing bar and the end of the lower reinforcing bar are connected via an arc-shaped portion.

[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, the spiral reinforcing bars 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 bars that connect the joint reinforcing bars to each other, and by ensuring the bending strength and strength of the joint section against negative bending, it is possible to prevent the joint section from being damaged by negative bending. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of a spiral reinforcing bar 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] 1(a) to 1(c) are schematic plan views illustrating a state in which a spiral reinforcing bar is bound to a joint reinforcing bar in a joint reinforcement structure 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 reinforcing bar structure 15 for a joint using a spiral reinforcing bar according to a preferred embodiment of the present invention is a reinforcing bar structure in which a spiral reinforcing bar 10, as shown in Fig. 1, is arranged in a joint extending in a direction intersecting the main girder in a portion between a pair of adjacent precast PC decks. For example, in the repair work of an existing road bridge, when an aging concrete deck is replaced with a precast PC deck 20, preferably made of precast concrete, the spiral reinforcing bar 10 shown in Fig. 1 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 Fig. 8, and is used as reinforcing bars for forming a reinforcing bar structure 15 for the joints 22 (see Figs. 4(a) to 4(c)) together with the joint reinforcing bar 21 protruding from the end face 20a of the precast PC deck 20, prior to pouring concrete into the joints 22. The joint reinforcement structure 15 using the spiral reinforcing bars 10 of this embodiment allows for smooth positioning and reinforcement at the joint 22 between a pair of adjacent precast PC deck slabs 20, and by expanding the range over which the concrete's restraining effect extends, it is possible to omit the straight connecting main reinforcements that connect the joint reinforcing bars 21 to each other, and by ensuring the bending strength and strength of the joint against negative bending, it is possible to prevent the joint from being damaged by negative bending.

[0020] The spiral reinforcing bar 10 used in the reinforcement structure 15 of the joint section using the spiral reinforcing bar 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 is a spiral-shaped reinforcing bar that forms the reinforcement structure 15 at the joint section 22 together with the joint reinforcing bars 21 that each protrude from the end faces 20a of the precast PC deck slabs 20 on both sides facing each other in this pouring space. The spiral reinforcing bar 10 used in the reinforcement structure 15 of the joint section using the spiral reinforcing bar of this embodiment has a spiral shape in which multiple unit spiral reinforcing bars 11 having a rectangular front shape (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 shape, 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 the bottom, 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 the bottom.

[0021] In this embodiment, the joint reinforcing bars 21 protruding from the end faces 20a of the precast PC deck 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). 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 longitudinal direction X of the joint portion 22 (see Figure 7(a)). By connecting the spiral reinforcing bar 11 and the joint reinforcing bar 21 in a positional relationship in which 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 bar 11d of the other long side portion is arranged at the same height position as the upper reinforcing bar 21a of the joint reinforcing bar 21, the spiral reinforcing bar can be installed in the concrete pouring space of the joint portion 22 without eroding the cover thickness above the upper reinforcing bar 21a.

[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 is a deformed reinforcing bar with a diameter of, for example, about 10 mm. A special reinforcing bar bending machine can easily be used to bend a single reinforcing bar into a spiral shape. 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 each 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, the lower 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.

[0025] If the spiral reinforcing bar 10 cannot be formed from a single reinforcing bar to a length equivalent to the extension of the joint portion 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 spiral axial direction X, thereby forming a spiral reinforcing bar 10 with a length equivalent to the extension of the joint portion 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, 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] As shown in FIG. 7(a), the spiral reinforcing bar 10 used in the joint reinforcement structure 15 using the spiral reinforcing bar of this embodiment has three sides, consisting of a pair of left and right short side parts 11a, 11b and one long side part 11c, arranged on an imaginary base plane P, and is preferably arranged at intervals between joint reinforcing bars 21 made of loop reinforcing bars, which are alternately arranged at a predetermined pitch s', which is the same as the pitch s of the unit spiral reinforcing bars 11 of the spiral reinforcing bar 10, and the other long side part 11d The diagonal connecting bars made of the spiral reinforcing bars 11 are preferably arranged so as to intersect with the upper reinforcing bars 21a of the joint reinforcing bars 21 at the same height as the upper reinforcing bars 21a, and one horizontal edge portion 11c of each unit spiral reinforcing bar 11 constituting the spiral reinforcing bar 10 is arranged at the same height as the upper reinforcing bars 21a of the joint reinforcing bars 21, and are tied together using, for example, a tie wire 12, so that reinforcement can be arranged in the joint part 22 without eroding the cover thickness above the upper reinforcing bars 21a. This makes it possible to easily form the joint part reinforcement structure 15 together with the joint reinforcing bars 21, which are preferably made of loop reinforcing bars arranged alternately. Furthermore, as described above, the other horizontal side portion 11d of the unit spiral reinforcing bar 11 can be arranged at the same height as the upper reinforcing bar 21a of the joint reinforcing bar 21 and can be kept in a state where the cover thickness above the upper reinforcing bar 21a is not eroded, so that the upper reinforcing bar 21a of the joint reinforcing bar 21, which has high tensile stiffness, can be arranged at the upper limit height position while ensuring a predetermined cover thickness. As a result, the reinforcement structure of the joint part using the spiral reinforcing bar of this embodiment can sufficiently ensure the bending strength and strength of the joint part 22 against negative bending that generates tensile stress on the upward side, and can effectively prevent the joint part 22 from being damaged by negative bending.

[0028] Here, the other horizontal side portion 11d of the unit spiral reinforcing bar 11 can be arranged so as to intersect with the upper reinforcing bar 21a of the joint reinforcing bar 21, and can be arranged at the same height as the upper reinforcing bar 21a. In this case, by arranging the upper reinforcing bar 21a of the joint reinforcing bar 21 lower by the diameter of the reinforcing bars that make up the spiral reinforcing bar 10, it is possible to ensure the cover thickness of the upper reinforcing bar 21a, including the other horizontal side portion 11d of the unit spiral reinforcing bar 11 that intersects with the upper reinforcing bar 21a, and to maintain sufficient bending strength and strength required for the joint part 22. In addition, it is preferable that the horizontal side portion 11c of one long side portion of the unit spiral reinforcing bar 11 arranged on the imaginary base plane P be arranged at the same height as the lower reinforcing bar 21b of the joint reinforcing bar 21. Since the horizontal edge portion 11c of one long side portion of the unit spiral reinforcing bar 11 does not need to be positioned so as to intersect with the lower reinforcing bar 21b, if sufficient cover thickness can be secured below the lower reinforcing bar 21b, the lower reinforcing bar 21b can be positioned lower by the diameter of the reinforcing bar that makes up the spiral reinforcing bar 10, thereby improving the strength of the precast PC deck slab 20.

[0029] In addition, in this embodiment, the reinforcing bar structure 15 of the joint portion is a reinforcing bar structure using spiral reinforcing bars 10, which is 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, which are arranged in two stages above and below, are connected via arc-shaped portions 21c, and each of the joint reinforcing bars 21 arranged on the imaginary base surface P of the spiral reinforcing bars 10 is The spiral reinforcing bar 10 is attached to the joint section 22 with the three side sections 11a, 11b, and 11c of the unit spiral reinforcing bar 11 arranged in the spaces between the alternatingly arranged joint reinforcing bars 21, and the diagonal connecting bars 11d 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 outside in the axial direction X, 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 positioned so as to be surrounded by a rectangular frame shape of the unit spiral reinforcing bars 11, as shown in Figure 5(b). The attached spiral reinforcing bar 10 and the joint reinforcing bar 21 are connected by preferably binding them with binding wires 12 (see Figure 7 (see)), and are installed in the concrete pouring space of the joint section 22. The spiral reinforcing bar 10 and the joint reinforcing bar 21 can be connected by binding with a binding wire 12 or by various other connecting means such as clips or spacers.

[0030] As a result, the joint reinforcement structure 15 using spiral reinforcing bars of this embodiment allows for smooth positioning and reinforcement at the joint between a pair of adjacent precast PC deck slabs 20, making it easy to form the joint reinforcement structure 15 together with the joint reinforcement bars 21. Furthermore, by expanding the range of the concrete's restraint effect, it becomes possible to omit the linear connecting main reinforcements that connect the joint reinforcement bars 21 to each other. Furthermore, the joint reinforcement structure 15 using spiral reinforcing bars of this embodiment ensures the bending strength and strength of the joint 22 against negative bending, which generates tensile stress on the upward side, and prevents the joint 22 from being damaged by negative bending. This also effectively prevents the precast PC deck slab 20 from becoming thicker than necessary.

[0031] 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 unit spiral reinforcing bars 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 unit spiral reinforcing bars 11 of the spiral reinforcing bar 10.

[0032] In addition, in this embodiment, as shown in Figure 7(b), the spiral reinforcing bar 10 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 can also be installed in the concrete pouring space of the joint portion 22 by tying them together using, for example, a binding wire 12.

[0033] 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.

[0034] 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.

[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 alternately arranged 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 arranged. 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 other long side portion 11d positioned above the joint reinforcing bars 21, which are not positioned off-center, is bound to the joint reinforcing bars. 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 lower reinforcing bar 21d arranged in the lower tier and an upper reinforcing bar 21e arranged in the upper tier, which is a hook reinforcing bar with the tip of the straight portion curved in a hook shape.

[0037] In this case, the reinforcement structure 15' of the joint section is such that the three side portions 11a, 11b, and 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 spaces between the joint reinforcing bars 21' of the two-stage reinforcement arrangement consisting of the straight-shaped lower reinforcing bars 21d and the hooked upper 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 hooked upper reinforcing bars 21e of the joint reinforcing bars 21', and When viewed from outside the axial direction X of the spiral reinforcing bar 10, as shown in Figure 6(b), the area surrounded by the upper reinforcing bars 21e on both the left and right sides made of hook reinforcement and the straight-shaped lower 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] Furthermore, in this embodiment, the joint reinforcing bars that protrude from the end surface 20a of the precast PC deck 20 that constitutes the joint reinforcement structure 15 into the concrete pouring space of the joint 22 do not have to be the loop reinforcing bars or those that consist of the straight lower reinforcing bars 21d and the hooked upper reinforcing bars 21e described above. The joint reinforcing bars may be reinforcing bars in which the lower reinforcing bars 21d are hooked and the upper reinforcing bars 21e are straight, or the upper reinforcing bars and the lower reinforcing bars in 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 joint section reinforcement structure 15 is provided does not necessarily have to be the joint section 22 between multiple precast PC deck slabs 20 installed in a row 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 structure 15 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. 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 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. The attached spiral reinforcing bars 10 and the joint reinforcing bars are tied together using tie wires 12, so that the spiral reinforcing bars can be installed in the concrete pouring space of the joint section.

[0041] The spiral reinforcing bars used in the reinforcement structure of the joint using the spiral reinforcing bars of the present invention are 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 left and right vertical sides and a pair of top and bottom 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 elongated in an oval shape, the same effects can be achieved. The inclination angle of the diagonal continuous reinforcing bars (diagonal connecting reinforcing bars), which preferably extend 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]

[0042] 10 Spiral Reinforcement Bars 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 bottom rebar 21e Top 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 for joints using spiral reinforcing bars is provided in the concrete pouring space of joints extending in a direction intersecting the main girders in the portion between each pair of adjacent precast PC slabs, which are supported by a plurality of main girders erected between a pair of abutments and attached in a continuous manner in the extension direction of the main girders, 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 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 side portions of the spiral reinforcing bar, which are 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 bar formed by the other horizontal side portion is arranged at the same height position as the upper reinforcing bar of the joint reinforcing bar, thereby connecting the spiral reinforcing bar and the joint reinforcing bar in a positional relationship such that the cover thickness above the upper reinforcing bar is not eroded, resulting in a reinforcement structure of the joint section using a spiral reinforcing bar that is installed in the concrete pouring space of the joint section.

2. 2. A reinforcement structure for a joint using spiral reinforcement according to claim 1, wherein the upper reinforcement of the joint reinforcement is arranged at a position lower by an amount corresponding to the thickness of the diagonal connecting reinforcement.

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 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. 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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