Bar arrangement structure for joint part using spiral reinforcement

Abstract

To easily construct a bar arrangement structure for a joint part that can be reinforced to secure necessary strength.SOLUTION: In a bar arrangement structure 15 for a joint part using spiral reinforcement 10 which is provided in a concrete placing space of the joint part 22 between a pair of adjoining concrete slabs 20, the spiral reinforcement 10 has a spiral form where a plurality of unit spiral reinforcement bars 11 having a rectangular front shape resulting from a bending processing of one reinforcement bar are continued at a prescribed pitch. Loop-like joint reinforcement bars 21 are alternately arranged in zigzag in a length direction X of the joint part 22. The spiral reinforcement 10 is arranged in the joint part 22 in a state where three side parts 11a, 11b, 11c of a unit spiral reinforcement bar 11 arranged on a virtual base surface P are arranged in a gap part between the loop-like joint reinforcement bars 21 and a diagonal connection bar 11d which is the other longer side is arranged to cross an upper reinforcement bar 21a.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a reinforcement structure for a joint using spiral reinforcing bars, and more particularly to a reinforcement structure for 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 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 on-site positioning of the joint time-consuming, and the range of the concrete restraint effect of the spiral reinforcing bar is limited to the circular area, preferably 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, which are arranged, for example, outside the annular part where the loop joint reinforcing bars overlap.When forming joints in precast decks using spiral reinforcing bars, it is desirable to be able to easily construct a reinforcement structure for the joint that can be reinforced to ensure the necessary strength.

[0009] The present invention aims to provide a reinforcement structure for a joint using spiral reinforcing bars that allows for smooth positioning and reinforcement of spiral reinforcing bars at the joint between a pair of adjacent concrete slabs, preferably precast PC deck slabs, and that makes it possible to omit the linear connecting main reinforcements that connect the joint reinforcing bars to each other by expanding the range over which the restraining effect of the concrete extends, and that makes it possible to easily construct a reinforcement structure for the joint that can be reinforced to ensure the necessary strength when forming a joint of a precast deck slab using spiral reinforcing bars. [Means for solving the problem]

[0010] The present invention provides a reinforcement structure for 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 reinforcing bars have a spiral shape in which a plurality of unit spiral reinforcing bars, each having a rectangular front view, are connected at a predetermined pitch in the axial direction of the spiral by bending a single reinforcing bar. Each of the unit spiral reinforcing bars has a pair of left and right short side portions and one long side portion of the rectangular front view, which are arranged on an imaginary base surface, and the other long side portion is an oblique connecting bar extending in a direction inclined at an angle of 10 to 35 degrees in top view relative to the imaginary base surface on which these three side portions are arranged, thereby forming a Z-spiral shape with a continuous Z shape in top view. 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 the joint reinforcing bars protrude from one end face of the concrete slab and the joint reinforcing bars protrude from the other end face of the concrete slab in a staggered pattern in the length direction of the joint. The spiral reinforcing bar is attached to the joint part 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 joint reinforcing bars are loop-shaped reinforcing bars in which the ends of the upper reinforcing bars and the lower reinforcing bars arranged in two tiers above and below are connected via arc-shaped portions. 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 spiral reinforcing bar is attached to the joint part 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 bar is attached to the joint part in an axial direction. The above-mentioned object has been achieved by providing a reinforcement structure for a joint section using spiral reinforcing bars arranged in the concrete pouring space of the joint section, by connecting the attached spiral reinforcing bars and the joint reinforcing bars in a position where, when viewed from the outside, the area where the loop-shaped joint reinforcing bars protruding from one end face of the concrete slab and the loop-shaped joint reinforcing bars protruding from the other end face of the concrete slab overlap is surrounded by a rectangular frame shape made up of the unit spiral reinforcing bars.

[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 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.

[0012] 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.

[0013] Furthermore, it is preferable that the reinforcement structure of the joint section using the spiral steel bars of the present invention is such that the joint section between a pair of adjacent concrete slabs is a joint section between a pair of precast PC deck slabs installed adjacent to each other.

[0014] 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]

[0015] 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 the spiral reinforcing bars in 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.In addition, when forming a joint section of a precast deck slab using spiral reinforcing bars, it is possible to easily construct a reinforcement structure of the joint section that can be reinforced to ensure the necessary strength. [Brief explanation of the drawings]

[0016] [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 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 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 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

[0017] A joint reinforcement structure 15 using a spiral reinforcing bar according to a preferred embodiment of the present invention can be formed, for example, using a spiral reinforcing bar 10 for a joint shown in Fig. 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 Fig. 8, and is used as reinforcing bars for forming a reinforcement structure 15 for the joints 22 (see Figs. 4(a) to (c)) together with joint reinforcing bars 21 protruding from the end face 20a of the precast PC deck 20, prior to pouring concrete into the joints 22. The spiral reinforcing bar 10 used in the reinforcement structure 15 of the joint section 22 in this embodiment is designed to be smoothly positioned and reinforced at the joint section 22 between a pair of adjacent precast PC deck slabs 20, and has the function of expanding the range over which the restraining effect of the concrete extends, thereby making it possible to omit the straight connecting main reinforcement that connects the joint reinforcing bars 21 to each other.

[0018] In this embodiment, the spiral reinforcing bars 10 used in the reinforcement structure 15 of the joint portion 22 are arranged in the concrete pouring space of the joint portion 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, form the reinforcement structure 15 in the joint portion 22.

[0019] In this embodiment, the spiral reinforcing bar 10 has a spiral shape in which a plurality of unit spiral reinforcing bars 11, each having a rectangular front view (see FIG. 3), are connected at a predetermined pitch in the spiral axial direction X by bending a single reinforcing bar (see FIGS. 1, 2(a), and 2(b)). Each 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 FIGS. 2(a) and 2(b)). The other horizontal side portion, the long side portion 11d, acts as an oblique connecting bar extending in a direction inclined at an angle θ of 10 to 35 degrees, more preferably 10 to 20 degrees, in top view with respect to the imaginary base plane P on which these three side portions are arranged (see FIG. 2(a)). This results in a Z-spiral shape in which Z shapes are continuous when viewed from above.

[0020] 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)). The spiral reinforcing bar 10 can be arranged in the joint portion 22 with the three side portions 11a, 11b, and 11c of the unit spiral reinforcing bar 11 arranged on the imaginary base surface P arranged in the spaces between the alternately arranged joint reinforcing bars 21, and the diagonal connecting bar 11d of the other long side portion arranged so as to intersect with the upper reinforcing bars 21a.

[0021] 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)).

[0022] 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.

[0023] 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.

[0024] When the spiral reinforcing bar 10 cannot be formed from a single reinforcing bar to have a length equivalent to the extension of the joint 22, multiple spiral reinforcing bars 10 are formed from multiple reinforcing bars. Then, for example, by overlapping and binding the ends as a lap part, the spiral reinforcing bars 10 are integrally connected in the axial direction X of the spiral, thereby forming a spiral reinforcing bar 10 for a joint having a length equivalent to the extension of the joint 22.

[0025] 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.

[0026] 7(a), the spiral reinforcing bar 10 used in the reinforcement structure 15 of the joint portion 22 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 loop 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, 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 arrange reinforcement in the joint portion 22. This makes it possible to easily form the reinforcement structure 15 of the joint portion 22 together with the joint reinforcing bars 21, preferably loop reinforcing bars, which are alternately arranged.

[0027] In other words, the joint section reinforcement structure 15 of this embodiment is a reinforcement structure using spiral reinforcing bars 10 that is provided in the concrete pouring space of the joint section 22 between a pair of adjacent concrete slabs, preferably a pair of precast PC floor slabs 20, and the joint reinforcing bars 21 each 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 section 22, with multiple joint reinforcing bars 21 protruding from the end face 20a of one precast PC floor slab 20 and multiple joint reinforcing bars 21 protruding from the end face 20a of the other precast PC floor slab 20 being arranged alternately in a staggered pattern in the longitudinal direction X of the joint section 22.

[0028] In this embodiment, the joint reinforcing bars 21 are arranged in this manner, and the joint reinforcing bars 21 are loop-shaped reinforcing bars in which the ends of the upper reinforcing bars 21a and the lower reinforcing bars 21b, which are arranged in two layers above and below, are connected via the arc-shaped portions 21c. In the reinforcement structure 15 of the joint section of this embodiment, the three side portions 11a, 11b, and 11c of each unit spiral reinforcing bar 11 arranged on the imaginary base surface P of the spiral reinforcing bar 10 are arranged in the spaces between the alternately arranged joint reinforcing bars 21, and the spiral reinforcing bars 10 are attached to the joint section 22 in a state where 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, one of the precast PC deck slabs 5(b), the area where the loop-shaped joint reinforcing bar 21 protruding from the end face 20a of the first precast PC deck 20 overlaps with the loop-shaped joint reinforcing bar 21 protruding from the end face 20a of the other precast PC deck 20 is surrounded by a rectangular frame shape of the unit spiral reinforcing bars 11, and the attached spiral reinforcing bar 10 and joint reinforcing bar 21 are connected by binding, preferably, with binding wires 12 (see FIG. 7), and are installed in the concrete pouring space of the joint part 22. The connection between the spiral reinforcing bar 10 and 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, the reinforcement structure 15 for the joint section 22 using the spiral reinforcing bars 10 of this embodiment allows for smooth positioning and placement of the spiral reinforcing bars 10 at the joint section 22 between a pair of adjacent precast PC deck slabs 20, making it easy to form the joint section reinforcement structure 15 together with the joint reinforcing bars 21. Furthermore, by expanding the range of the concrete's restraint effect, it becomes possible to omit the linear connecting main reinforcing bars that connect the joint reinforcing bars 21 to each other. That is, the reinforcement structure 15 for the joint section 22 of this embodiment can be strongly reinforced by arranging the reinforcing bars around the periphery of the overlapping area of ​​the joint reinforcing bars, eliminating the need for reinforcing bars perpendicular to the bridge axis. This also effectively prevents the precast PC deck slab 20 from becoming thicker than necessary. Furthermore, construction is simplified because the diagonal side of the Z spiral reinforcing bars simply needs to be placed on the upper end reinforcing bars of the loop joint and secured in place. Furthermore, in this embodiment, the joint structure is a combination of the deck slab joint reinforcement made of joint reinforcement 21, which is a loop-shaped semicircular loop reinforcement protruding from the end of the deck slab, and the spiral reinforcement 10, which is a Z spiral reinforcement.Therefore, the inner area where the loop-shaped joint reinforcement 21 overlaps is strengthened by being surrounded by the inner surface of the spiral reinforcement 10, which is a Z spiral reinforcement, due to the so-called confining effect, which makes it possible to eliminate the need for reinforcing reinforcement in the direction perpendicular to the bridge axis.

[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 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.

[0031] In addition, in this embodiment, as shown in Figure 7(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 with the three side portions 11a, 11b, and 11c arranged on the virtual base surface P in close proximity to or in contact with one of the joint reinforcing bars 21 on both sides of the gap, and then placing them to one side.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] In this embodiment, the joint reinforcing bars 21, 21' that protrude from the end face 20a of the precast PC deck 20 constituting the reinforcement structure 15, 15' of the joint portion 22 into the concrete pouring space of the joint portion 22 do not have to be the loop reinforcing bars or the straight upper reinforcing bars 21d and the hooked lower reinforcing bars 21e described above. The joint reinforcing bars may also be straight upper and lower reinforcing bars in a two-stage reinforcement arrangement (not shown).

[0037] Furthermore, the joint section to which the spiral reinforcing bar 10 is attached and the reinforcement structure 15 of the joint section 22 is provided does not necessarily have to be the joint section 22 between multiple precast PC deck slabs 20 installed in a continuous state 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.

[0038] Therefore, in this embodiment, the reinforcement structure 15 of the joint portion 22 is a reinforcement 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, and the joint reinforcing bars 21, which each protrude from the end faces of the concrete slabs on both opposing sides in the concrete pouring space of the joint portion 22 and form a two-stage reinforcement including upper reinforcing bars and lower reinforcing bars, are arranged so that 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 alternately in a staggered pattern along the length of the joint portion. In the reinforcement structure 15 of the joint section 22 of this embodiment, the spiral reinforcement 10 is attached to the joint section 22 in a state in which the three side portions 11a, 11b, and 11c of the spiral reinforcement 10 arranged on the imaginary base surface P are arranged in the spaces between the alternately arranged joint reinforcement, and the diagonal connecting bar 11d is arranged so as to intersect with the upper reinforcement of the joint reinforcement, and the attached spiral reinforcement 10 and the joint reinforcement are tied together using a tie wire 12, so that the spiral reinforcement 10 can be installed in the concrete pouring space of the joint section.

[0039] In this embodiment, the spiral reinforcing bar 10 attached to the joint portion 22 has a horizontally elongated rectangular side that surrounds the outer periphery of the joint area, reinforcing the concrete inside and increasing its rigidity and strength. Furthermore, three of the four sides of the unit spiral reinforcing bar 11 of the spiral reinforcing bar 10 are on the same plane, and only one side is arranged diagonally from the plane to connect the next three sides. Therefore, in this embodiment, when forming the joint portion 22 of a precast deck slab using the spiral reinforcing bar 10 with this configuration, the three sides on the same plane are arranged along the side surfaces of the loop joint of the deck slab, which makes it easier to install and bind the spiral reinforcing bar 10 and pour concrete, and thus facilitates the construction of a reinforcement structure 15 for the joint portion 22 that can be reinforced to ensure the required strength.

[0040] In particular, the reinforcement structure 15 of the joint section 22 in this embodiment is a joint structure in which the joint reinforcing bars 21 protruding from the end of the deck slab are combined as loop-shaped semicircular loop reinforcement with the spiral reinforcing bars 10 which are Z spiral reinforcement, and the inner area of ​​the range where the loop-shaped joint reinforcing bars 21 overlap is arranged so that the inner surface of the spiral reinforcing bar 10 surrounds it.This makes it possible to easily construct the reinforcement structure 15 of the joint section 22 which can be reinforced so that the required strength can be ensured even with fewer reinforcement bars, eliminating the need for reinforcement bars perpendicular to the bridge axis.

[0041] The reinforcement structure of a joint using a spiral reinforcing bar according to 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 elongated oval shapes. The inclination angle of the diagonal continuous reinforcing bars (diagonal connecting reinforcing bars), which are preferably installed 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 Loop splice reinforcing bars 21' Reinforced Concrete Joint 21a Upper reinforcing bar 21b Bottom reinforcing bar 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 short side portions and one long side portion of the rectangular frontal shape arranged on an imaginary base surface, and the other long 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 portion, 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 portion, and the joint reinforcing bars are loop-shaped reinforcing bars in which the ends of the upper reinforcing bars and the lower reinforcing bars arranged in two tiers, one above the other, are connected via arc-shaped portions, The spiral reinforcing bar is attached to the joint section with the three side portions arranged on the virtual base surface of the spiral reinforcing bar arranged in the spaces between the alternatingly arranged joint reinforcing bars, and the diagonal connecting bars arranged so as to intersect with the upper reinforcing bars of the joint reinforcing bars, and when the attached spiral reinforcing bar is projected from the outside in the axial direction, the area where the loop-shaped joint reinforcing bar protruding from one end face of the concrete slab and the loop-shaped joint reinforcing bar protruding from the other end face of the concrete slab overlap is surrounded by a rectangular frame shape made up of the unit spiral reinforcing bars, and the attached spiral reinforcing bar and the joint reinforcing bar are connected in this position, resulting in a reinforcement structure of the joint section using a spiral reinforcing bar installed in the concrete pouring space of the joint section.

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 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.

4. 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.

5. 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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