Joint structure between precast PC floor slab and girder
By installing studs between perforated steel shear keys and filling the joint with mortar, the joint structure between precast PC floor slabs and girders achieves high strength and durability while maintaining design flexibility.
Patent Information
- Application Number
- JP2023210846
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-12-14
- Publication Date
- 2025-06-26
AI Technical Summary
Existing joint structures between precast PC floor slabs and girders face challenges in achieving high strength and durability while maintaining design flexibility, due to restrictions in arranging prestressing steel and drain grooves, and potential weaknesses in the joint area.
The solution involves installing studs on the top surface of the girder between perforated steel shear keys protruding from the bottom surface of the precast PC floor slab, and filling the joint with a filling material such as mortar.
This configuration allows for a girder structure with high strength and durability without reducing the design freedom of the precast PC floor slabs, while also mitigating stress concentration at the stud base.
Smart Images
Figure 2025095064000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a joint structure between a precast PC floor slab and a girder.
Background Art
[0002] For example, when joining a precast PC floor slab and a steel girder in floor slab replacement work for an existing steel girder bridge or bridge work for a new steel girder bridge, as described in Non-Patent Document 1, studs such as headed studs in the required number for design are welded to the required locations on the flange of the steel girder. On the other hand, the floor slab is provided with a punched-out portion (also referred to as a "dowel hole"), which is a through-hole for receiving the studs. Then, after the floor slab is erected on the steel girder so that the studs are inserted into the punched-out portion, the joint portion, which is the space between the two, is filled with non-shrink mortar, and expansive concrete is driven into the punched-out portion. Thereby, the floor slab and the steel girder can be firmly joined to prevent displacement between the two.
[0003] However, since the positions and numbers of the studs to be welded are determined by the structure of the steel girder bridge, the positions and shapes of the punched-out portions provided in the floor slab also differ depending on the structure of the steel girder bridge. Therefore, for example, the arrangement of the prestressing steel and / or drain grooves in the precast PC floor slab is restricted, which has been a factor in reducing the degree of freedom in the design of the floor slab. In addition, as described above, the punched-out portion is a through-hole into which expansive concrete is driven after the floor slab is erected on the steel girder, and since reinforcing members such as prestressing steel cannot be arranged in this portion, it can be a weakness in the strength and / or durability of the floor slab. Furthermore, the placement of expansive concrete into the punched-out portion may increase the work load at the construction site or cause deterioration of the floor slab, leading to a decrease in the durability of the steel girder bridge.
Prior Art Documents
Non-Patent Documents
[0004]
Non-Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] As described above, in this technical field, there is a demand for a technology that can achieve a girder structure with high strength and durability without reducing the degree of freedom in the design of precast PC floor slabs.
[0006] The present disclosure has been made in view of the above problems, and an object thereof is to achieve a girder structure having high strength and durability without reducing the degree of freedom in the design of precast PC floor slabs.
Means for Solving the Problems
[0007] As a result of intensive research, the inventor has found that the above problems can be solved by installing studs on the top surface of the girder so as to be located between at least a pair of perforated steel shear keys installed so as to protrude from the bottom surface of the floor slab at the joint, which is the space between the precast PC floor slab and the girder, and filling the joint with a filling material such as mortar.
[0008] Specifically, in the joint structure between the precast PC floor slab and the girder according to the present disclosure (hereinafter also referred to as "the present disclosure structure"), the precast PC floor slab is provided with at least a pair of perforated steel plate dowels installed so as to protrude from the floor slab joint surface, which is the surface facing the girder of the precast PC floor slab. Further, the girder is provided with at least one stud installed so as to protrude between the paired perforated steel plate dowels from the girder joint surface, which is the surface facing the precast PC floor slab. In addition, the precast PC floor slab and the girder are connected via the perforated steel plate dowels and the studs by a filler that is poured into and cured in the joint, which is the space between the precast PC floor slab and the girder. Preferably, the perforated steel plate dowels are arranged so as to be parallel to both the bridge axis direction and the vertical direction.
[0009] Another aspect of the present disclosure structure further includes a through-bar, which is a reinforcing bar inserted so as to span both of the through-holes respectively drilled in the paired perforated steel plate dowels at the joint. In a preferred aspect of this embodiment, a plurality of through-holes are drilled in the paired perforated steel plate dowels at the joint, a plurality of through-bars are inserted into the plurality of through-holes, and the studs are positioned between the plurality of through-bars.
[0010] Furthermore, another aspect of the present disclosure structure further includes an enclosing member, which is a cylindrical member provided with a gap on the side surface such that the filler before being cured can flow from the outside to the inside. And the base end region, which is the region adjacent to the girder joint surface of at least some of the studs, is inserted into the inside of the enclosing member.
Advantages of the Invention
[0011] According to the joint structure between the precast PC floor slab and the girder according to the present disclosure (the present disclosure structure), it is possible to achieve a girder structure having high strength and durability without reducing the degree of freedom in the design of the precast PC floor slab.
Brief Description of the Drawings
[0012]
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Embodiments for Carrying Out the Invention
[0013] Embodiments for carrying out the invention according to the present disclosure will be described below. Prior to that, a joining structure between a precast PC floor slab and a girder according to the prior art (hereinafter also referred to as "conventional structure") will be described.
[0014] FIG. 12 is a schematic cross-sectional view showing an example of a joining structure between a precast PC floor slab and a girder according to the prior art (hereinafter also referred to as "conventional structure"). FIG. 12(a) is a cross-sectional view of the conventional structure 200 by a plane parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. FIG. 12(b) is a cross-sectional view of the conventional structure 200 by a plane parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10.
[0015] Further, FIG. 13 is a schematic diagram exemplifying the configuration of a bridge including a precast PC floor slab 30 and a girder 20 joined by the conventional structure 200. FIG. 13(a) is a cross-sectional view of the bridge by a plane parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. FIG. 13(b) is a cross-sectional view by a plane parallel to both the bridge axis direction (x-axis direction) and the width direction (y-axis direction) and passing through the joint portion 40 which is the space between the precast PC floor slab 30 and the girder 20 (plane A-A shown in FIG. 13(a)). FIG. 13(c) is a cross-sectional view of the bridge by a plane parallel to both the width direction (y-axis direction) and the vertical direction (x-axis direction) and passing through the stud 10 (plane B-B shown in FIG. 13(a)). FIG. 13(d) is a cross-sectional view of the bridge by a plane parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and not passing through the cut-out portion 31 (plane C-C shown in FIG. 13(a)).
[0016] As illustrated in FIGS. 12 and 13, in the conventional structure 200, the required number of studs 10 are installed at the required locations on the girder 20 by means such as welding. On the other hand, in the precast PC floor slab 30, a knockout part (dowel hole) 31, which is a through hole for receiving the stud 10, is provided in advance. Then, after the precast PC floor slab 30 is erected on the girder 20 such that the stud 10 is inserted into the knockout part 31, a filling material 51 such as non-shrink mortar is filled in the joint part 40, which is the space between the two, and a filling material 52 such as expansive concrete is driven into the knockout part 31. Thereby, the precast PC floor slab 30 and the girder 20 can be firmly joined to prevent displacement between the two.
[0017] However, the position and number of the studs 10 are determined by, for example, the structure of a building such as a bridge including the joint structure between the precast PC floor slab 30 and the girder 20, and the strength required for the building. For this reason, the position and shape of the knockout 31 provided in the precast PC floor slab 30 also differ depending on the structure of the building. Therefore, for example, the arrangement of the pretensioned steel materials and / or drain gutters (both not shown) in the precast PC floor slab 30 is restricted, which has been a factor reducing the degree of freedom in the design of the precast PC floor slab 30. Also, as described above, the knockout part 31 is a through hole into which the filling material 52 is driven after the precast PC floor slab 30 is erected on the girder 20, and since reinforcing members such as pretensioned steel materials cannot be arranged in this part, it can be a weakness in terms of the strength and / or durability of the floor slab. Furthermore, the placing of the filling material 52 into the knockout part 31 may increase the work load at the construction site and may become a factor in the deterioration of the floor slab, leading to a reduction in the durability of the building.
[0018] Therefore, as described above, as a result of intensive research, the inventor of the present invention has found that at least a pair of perforated steel shear connectors (hereinafter also referred to as "PBL") installed so as to protrude from the bottom surface of the floor slab are located between the precast PC floor slab and the girder, which is the space between them. By installing studs on the top surface of the girder so as to be located between them and filling the joint with a filling material such as mortar, the above problems can be solved.
[0019] 《First Embodiment》 Hereinafter, with reference to the drawings, a joint structure between a precast PC floor slab and a girder according to the first embodiment of the present disclosure (hereinafter also referred to as "first structure") will be described. The first structure achieves a girder structure having high strength and durability without reducing the degree of freedom in the design of the precast PC floor slab in a building such as a steel girder bridge.
[0020] 〈Configuration〉 FIG. 1 is a schematic cross-sectional view showing an example of the first structure. FIG. 1(a) is a cross-sectional view by a plane parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. In FIG. 1(a), the PBL 60 is drawn for the purpose of facilitating the understanding of the present embodiment. However, it should be noted that the PBL 60 is actually located at a position shifted in the width direction (y-axis direction) from the cross-sectional view and does not originally appear in the cross-section. FIG. 1(b) is a cross-sectional view by a plane parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10.
[0021] Further, FIG. 2 is a schematic diagram illustrating the configuration of a bridge including a precast PC floor slab 30 and a girder 20 joined by the first structure 101 illustrated in FIG. 1. FIG. 2(a) is a cross-sectional view taken along a plane parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. Note that also in FIG. 2(a), similar to FIG. 1(a) described above, the PBL 60 is drawn for the purpose of facilitating the understanding of the present embodiment, but it should be noted that the PBL 60 is present at a position shifted in the width direction (y-axis direction) from the cross-sectional view and thus does not originally appear in the cross-section.
[0022] FIG. 2(b) is a cross-sectional view taken along a plane (plane D-D shown in FIG. 2(a)) parallel to both the bridge axis direction (x-axis direction) and the width direction (y-axis direction), passing through the joint portion 40 which is the space between the precast PC floor slab 30 and the girder 20, and not passing through the PBL 60. FIG. 2(c) is a cross-sectional view taken along a plane (plane E-E shown in FIG. 2(a)) parallel to both the bridge axis direction (x-axis direction) and the width direction (y-axis direction), passing through the joint portion 40 and passing through the PBL 60. FIG. 2(d) is a cross-sectional view taken along a plane (plane F-F shown in FIG. 2(a)) parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. FIG. 2(e) is a cross-sectional view taken along a plane (plane G-G shown in FIG. 2(a)) parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction), passing through the PBL 60 and not passing through the stud 10. FIG. 2(f) is a cross-sectional view taken along a plane (plane H-H shown in FIG. 2(a)) parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and not passing through the PBL 60.
[0023] As illustrated in FIGS. 1 and 2, in the first structure 101, the precast PC floor slab 30 includes at least a pair of PBLs 60 installed so as to protrude from the floor slab joint surface which is the surface of the precast PC floor slab 30 facing the girder 20.
[0024] As the precast PC floor slab 30 and girders 20 that constitute the first structure 101, for example, precast PC floor slabs and steel girders widely used in structures such as steel truss bridges can be adopted. Also, as the PBL60, for example, PBL widely used in the anti-slip applications of steel-concrete composite structures can be adopted.
[0025] The precast PC floor slab 30 illustrated in FIGS. 1 and 2 is provided with two pairs of PBL60 per individual floor slab joint surface. However, regarding the number, position, size, etc. of the PBL installed in the precast PC floor slab 30, for example, it can be appropriately determined according to the arrangement of reinforcing members such as prestressing steel bars arranged inside the precast PC floor slab 30, the structure of a building such as a bridge including the first structure 101, and the strength required for the building.
[0026] Also, in the precast PC floor slab 30 illustrated in FIGS. 1 and 2, a part of the PBL60 is embedded inside the precast PC floor slab 30. Regarding the size (embedding depth) of the part of the PBL60 embedded inside the precast PC floor slab 30 in this way, for example, it can be appropriately determined according to the arrangement of reinforcing members such as prestressing steel bars arranged inside the precast PC floor slab 30, the structure of a building such as a bridge including the first structure 101, and the strength required for the building.
[0027] Furthermore, the method of installing the PBL60 so as to protrude from the floor slab joint surface of the precast PC floor slab 30 is not limited to the above. For example, FIG. 3 is a schematic cross-sectional view illustrating a first structure in which the precast PC floor slab 30 and the PBL60 are connected by embedding a stud 61 provided so as to protrude from the PBL60 inside the precast PC floor slab 30.
[0028] As shown in Fig. 3(a), similar to Fig. 1(a), it is a cross-sectional view taken by a plane parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. In Fig. 3(a), similar to Fig. 1(a), for the purpose of facilitating the understanding of this embodiment, PBL60 which is actually located at a position shifted in the width direction (y-axis direction) from the cross-sectional view and does not appear in the cross-section originally is depicted.
[0029] Fig. 3(b) is a cross-sectional view taken by a plane parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. In Fig. 3(b), for the purpose of facilitating the understanding of this embodiment, the stud 61 provided so as to protrude from the PBL60 is depicted, but the stud 61 is actually located at a position shifted in the bridge axis direction (x-axis direction) from the cross-sectional view and does not appear in the cross-section originally. Thus, the precast PC floor slab 30 and the PBL60 may be connected via other members.
[0030] Furthermore, the girder 20 includes at least one stud 10 installed so as to protrude between the paired PBL60s from the girder joint surface which is the surface facing the precast PC floor slab 30.
[0031] As the stud 10, for example, studs widely used in applications for preventing displacement in steel-concrete composite structures (such as headed studs, etc.) can be adopted. The girder 20 illustrated in Figs. 1 and 2 includes 4 studs 10 per girder joint surface facing each precast PC floor slab 30. However, regarding the number, position, thickness, length, etc. of the studs 10 installed on the girder 20, they can be appropriately determined according to, for example, the structure of a building such as a bridge including the first structure 101 and the strength required for the building. However, since the stud 10 needs to fit within the joint portion 40 which is the space between the precast PC floor slab and the girder, the length of the stud 10 needs to be equal to or less than the distance between the precast PC floor slab 30 and the girder 20 in the first structure 101 (that is, the distance between the floor slab joint surface and the girder joint surface).
[0032] The means for installing the stud 10 on the girder joint surface of the girder 10 is not particularly limited as long as it is possible to achieve the required strength, durability, etc. for structures such as bridges including the first structure 101. Specific examples of such means include, for example, welding (fusion welding) the stud 10 to the girder joint surface of the girder 10 or screwing the stud 10 to nuts welded to the girder joint surface of the girder 10.
[0033] In addition, as described above, the number of pairs of PBLs 60 provided in the precast PC floor slab 30 may be one or a plurality. When the precast PC floor slab 30 is provided with only one pair of PBLs 60, the pair of PBLs 60 may be installed so as to extend over the entire length or width of the precast PC floor slab 30. In this case, the advantage of a higher degree of freedom in the arrangement of the studs 10 installed on the girder joint surface of the girder 10 is obtained.
[0034] In addition, the precast PC floor slab 30 and the girder 20 are connected via the PBL 60 and the stud 10 by the filler 50 poured and cured in the joint portion 40, which is the space between the precast PC floor slab 30 and the girder 20.
[0035] As the filler 50, for example, depending on the structure of a structure such as a bridge including the first structure 101 and the strength required for the structure, a filler such as mortar can be adopted. Specific examples of such mortar include, for example, non-shrinking mortar and high-strength fiber-reinforced mortar.
[0036] In addition, in the first structure 101 illustrated in FIGS. 1 and 2, the PBL 60 is arranged so as to be parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction). However, FIGS. 1 and 2 are merely examples, and the orientation of the PBL 60 in the first structure 101 is not limited to the above.
[0037] However, as is clear from the configuration of the first structure 101 illustrated in FIGS. 1 and 2, the joint portion 40, which is the space between the precast PC floor slab 30 and the girder 20, extends along the girder 20. That is, the joint portion 40 is a space extending in the bridge axis direction (x-axis direction). Therefore, when the filler 50 is placed in the joint portion 40, the filler 50 flows in the bridge axis direction (x-axis direction). In order to sufficiently fill the joint portion 40 with a filler 50 such as mortar, for example, it is preferable that the filler 50 placed in the joint portion 40 easily reaches every corner of the joint portion 40. From such a viewpoint, as illustrated in FIGS. 1 and 2, it is preferable that the PBLs 60 are arranged so as to be parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction). By arranging the PBLs 60 in this way, when the filler 50 is placed in the joint portion 40, the degree to which the flow of the filler 50 is obstructed by the PBLs 60 is reduced, and the joint portion 40 can be sufficiently filled with the filler 50. Therefore, a girder structure having high strength and durability can be more reliably achieved.
[0038] <Effect> As described above, in the joint structure (first structure 101) of the precast PC floor slab and the girder according to the first embodiment of the present disclosure, the precast PC floor slab 30 and the girder 20 are connected via the PBLs 60 and the studs 10 by the filler 50 that is poured into and cured in the joint portion 40, which is the space between the precast PC floor slab 30 and the girder 20. That is, in the first structure 101, there is no need to provide the floor slab 30 with the knockout portion 31, which is a through hole for receiving the studs 10, as in the joint structure (conventional structure 200) of the precast PC floor slab and the girder according to the conventional technology described above.
[0039] Therefore, according to the first structure 101, a girder structure having high strength and durability can be achieved without reducing the degree of freedom in the design of the precast PC floor slab 30.
[0040] <<Second Embodiment>> Hereinafter, a joint structure of a precast PC floor slab and a girder according to the second embodiment of the present disclosure (hereinafter, also referred to as the "second structure") will be described with reference to the drawings.
[0041] As described above, according to the first structure 101, it is possible to achieve a girder structure having high strength and durability without reducing the degree of freedom in the design of the precast PC floor slab 30. However, for example, depending on the structure of a building such as a bridge including the first structure 101 and the strength required for the building, etc., it may be required to further increase the shear resistance in the direction parallel to the perforated steel plate shear connector (PBL) 60.
[0042] <Configuration> FIG. 4 is a schematic cross-sectional view showing an example of the second structure. FIG. 4(a) is a cross-sectional view by a plane parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. Similar to FIG. 1(a) referred to in the description of the first structure 101, in FIG. 4(a) as well, for the purpose of facilitating the understanding of the present embodiment, it should be noted that the PBL 60 which is present at a position shifted in the width direction (y-axis direction) from the cross-sectional view and would not originally appear in the cross-section is drawn. FIG. 4(b) is a cross-sectional view by a plane parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. In FIG. 4(b), for the purpose of facilitating the understanding of the present embodiment, the penetrating reinforcement 62 which is a reinforcement inserted so as to straddle both of the through holes respectively drilled in the PBL 60 is drawn, but it should be noted that the penetrating reinforcement 62 is present at a position shifted in the bridge axis direction (x-axis direction) from the cross-sectional view and would not originally appear in the cross-section.
[0043] Further, FIG. 5 is a schematic diagram illustrating the configuration of a bridge including a precast PC floor slab 30 and a girder 20 joined by the second structure 102 illustrated in FIG. 4. FIG. 5(a) is a cross-sectional view taken along a plane parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. Note that also in FIG. 5(a), similar to FIG. 1(a) referred to in the description of the first structure 101 and FIG. 4(a) described above, the PBL 60 is drawn for the purpose of facilitating the understanding of the present embodiment. However, it should be noted that the PBL 60 is present at a position shifted in the width direction (y-axis direction) from the cross-sectional view and thus would not originally appear in the cross-section.
[0044] FIG. 5(b) is a cross-sectional view taken along a plane (plane D-D shown in FIG. 5(a)) parallel to both the bridge axis direction (x-axis direction) and the width direction (y-axis direction), passing through the joint portion 40 which is the space between the precast PC floor slab 30 and the girder 20, and not passing through the PBL 60. FIG. 5(c) is a cross-sectional view taken along a plane (plane E-E shown in FIG. 5(a)) parallel to both the bridge axis direction (x-axis direction) and the width direction (y-axis direction), passing through the joint portion 40 and passing through the PBL 60 and the through reinforcing bar 62. FIG. 5(d) is a cross-sectional view taken along a plane (plane F-F shown in FIG. 5(a)) parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. FIG. 5(e) is a cross-sectional view taken along a plane (plane G-G shown in FIG. 5(a)) parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the through reinforcing bar 62. FIG. 5(f) is a cross-sectional view taken along a plane (plane H-H shown in FIG. 5(a)) parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and not passing through the PBL 60.
[0045] Furthermore, FIG. 6 is a schematic perspective view illustrating the configuration of a bridge including a joint structure between a precast PC floor slab and a girder joined by a second structure. Studs 10, PBLs 60, and through rebars 62 that are not normally visible from the outside are depicted by solid lines. Also, portions of the girder 20, the precast PC floor slab 30, and the filler 50 placed in the joint 40 that are not normally visible from the outside are depicted by dashed lines.
[0046] As illustrated in FIGS. 4 to 6, the second structure 102 has the same configuration as the above-described first structure 101, except that it further includes through rebars 62 that are inserted so as to span both of the through holes drilled in the paired PBLs 60 at the joint 40.
[0047] When it does not interfere with the work of installing the precast PC floor slab 30 on top of the girder 20, for example, the through rebars 62 may be inserted into the through holes drilled in the PBLs 60 before construction at the manufacturing base of the precast PC floor slab 30 or the like. Alternatively, for example, the through rebars 62 may be inserted into the through holes drilled in the PBLs 60 at the construction site of a building such as a bridge including the second structure 102. However, when using and storing a "sponge formwork" in which the placement section of the filler 50 is partitioned by a sole sponge, it is not possible to insert the through rebars 62 at the construction site, so it is necessary to insert the through rebars 62 into the through holes drilled in the PBLs 60 before construction.
[0048] Also, the through rebars 62 only need to be inserted so as to span both of the through holes drilled in the PBLs 60 in a state where the filler 50 has been poured and cured in the joint 40. Therefore, the through rebars 62 do not necessarily need to be fixed to the PBLs 60, but they need to remain in the through holes drilled in the PBLs 60 without falling out until the placement of the filler 50 in the joint 40 is completed. Thus, they may be tied to the PBLs 60 by a member such as a wire.
[0049] Furthermore, from the viewpoint of increasing the shear strength in the direction parallel to the PBL60, it is preferable that both ends of the through-bar 62 protrude as much as possible from the through-holes drilled in the paired PBL60s at the joint 40, as long as there are no problems such as interference with other surrounding members.
[0050] 〈Effect〉 According to the second structure 102 having the above configuration, the shear strength in the direction parallel to the PBL60 can be further increased.
[0051] In the second structure 102 according to the preferred embodiment, as illustrated in FIGS. 4 to 7, a plurality of through-holes are drilled in the paired PBL60s at the joint 40, a plurality of through-bars 62 are inserted into the plurality of through-holes, and the studs 10 are positioned between the plurality of through-bars 62. According to the second structure 102 having such a configuration, not only the shear strength in the direction parallel to the PBL60 but also the shear strength in the direction orthogonal to the PBL60 can be further increased.
[0052] 《Third Embodiment》 Hereinafter, a joint structure between a precast PC floor slab and a girder according to the third embodiment of the present disclosure (hereinafter, also referred to as "third structure") will be described with reference to the drawings.
[0053] As described above, according to the first structure 101, a girder structure having high strength and durability can be achieved without reducing the degree of freedom in the design of the precast PC floor slab 30. Furthermore, according to the second structure 102, not only the shear strength in the direction parallel to the perforated steel plate shear connector (PBL) 60 but also the shear strength in the direction orthogonal to the PBL60 can be further increased. In addition, according to the third structure, the filler 50 can be sufficiently filled in the joint 40, so that a girder structure having high strength and durability can be more reliably achieved.
[0054] However, also in the joint structure (the present disclosure structure) of the precast PC floor slab and the girder according to the present disclosure starting from the third structure including the first structure 101 described above, similar to the conventional structure, stress caused by the displacement between the precast PC floor slab 30 and the girder 20 tends to concentrate at the base of the stud 10. As a result, the base of the stud 10 (that is, the proximal region which is the region adjacent to the girder joint surface of the stud 10) tends to be the starting point of the deterioration and / or breakage of the joint structure between the precast PC floor slab 30 and the girder 20.
[0055] <Configuration> FIG. 7 is a schematic cross-sectional view showing an example of the third structure. FIG. 7(a) is a cross-sectional view by a plane parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. Note that, similar to FIGS. 1(a) and 4(a) respectively referred to in the description of the first structure 101 and the second structure 102, also in FIG. 7(a), for the purpose of facilitating the understanding of the present embodiment, the PBL 60 which exists at a position shifted in the width direction (y-axis direction) from the cross-sectional view and which would not originally appear in the cross-section is drawn. FIG. 7(b) is a cross-sectional view by a plane parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. Note that, similar to FIG. 4(b) referred to in the description of the second structure 102, also in FIG. 7(b), for the purpose of facilitating the understanding of the present embodiment, the through reinforcing bar 62 which exists at a position shifted in the bridge axis direction (x-axis direction) from the cross-sectional view and which would not originally appear in the cross-section is drawn.
[0056] Further, FIG. 8 is a schematic diagram illustrating the configuration of a bridge including a precast PC floor slab 30 and a girder 20 joined by the third structure 103 illustrated in FIG. 7. FIG. 8(a) is a cross-sectional view taken along a plane parallel to both the bridge axis direction (x-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. Note that also in FIG. 8(a), similar to FIG. 1(a) and FIG. 4(a) respectively referred to in the description of the first structure 101 and the second structure 102 and FIG. 7(a) described above, the PBL 60 is drawn for the purpose of facilitating the understanding of the present embodiment. However, it should be noted that the PBL 60 is present at a position shifted in the width direction (y-axis direction) from the cross-sectional view and thus does not originally appear in the cross-section.
[0057] FIG. 8(b) is a cross-sectional view taken along a plane (plane D-D shown in FIG. 8(a)) parallel to both the bridge axis direction (x-axis direction) and the width direction (y-axis direction) and passing through the joint portion 40 which is the space between the precast PC floor slab 30 and the girder 20 and not passing through the PBL 60. FIG. 8(c) is a cross-sectional view taken along a plane (plane E-E shown in FIG. 8(a)) parallel to both the bridge axis direction (x-axis direction) and the width direction (y-axis direction) and passing through the joint portion 40 and passing through the PBL 60 and the through-reinforcing bar 62. FIG. 8(d) is a cross-sectional view taken along a plane (plane F-F shown in FIG. 8(a)) parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the stud 10. FIG. 8(e) is a cross-sectional view taken along a plane (plane G-G shown in FIG. 8(a)) parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and passing through the through-reinforcing bar 62. FIG. 8(f) is a cross-sectional view taken along a plane (plane H-H shown in FIG. 8(a)) parallel to both the width direction (y-axis direction) and the vertical direction (z-axis direction) and not passing through the PBL 60.
[0058] As illustrated in FIGS. 7 and 8, the third structure 103 has the same configuration as the second structure 102 described above, except that it further includes an enclosing member 11 which is a cylindrical member surrounding each stud 10.
[0059] In the third structure 103 illustrated in FIGS. 7 and 8, a spiral bar, which is a reinforcing bar having a spiral shape as illustrated in FIG. 9(a), is adopted as the surrounding member 11, and all the studs 10 are individually surrounded by the spiral bar over substantially the entire length. However, the configuration and arrangement of the members that can be adopted as the surrounding member 11 are not limited to the examples shown in FIGS. 7, 8, and 9(a).
[0060] As described above, the stress caused by the displacement between the precast PC floor slab 30 and the girder 20 tends to concentrate in the base end region, which is the region adjacent to the girder joint surface of the stud 10. As a result, it tends to be the starting point of deterioration and / or breakage of the joint structure between the precast PC floor slab 30 and the girder 20. Therefore, it is not necessarily required that all the studs 10 be individually surrounded by the surrounding member 11 as in the third structure 103 illustrated in FIGS. 7 and 8 over substantially the entire length.
[0061] Specifically, the surrounding member 11 does not necessarily have to surround all the studs 10. For example, it may surround at least some of the studs 10, such as the studs 10 where the above-described stress is significantly concentrated. Further, the surrounding member 11 does not necessarily have to surround the studs 10 over the entire length, and it may surround the studs 10 at least in the base end region (i.e., the base portion), which is the region adjacent to the girder joint surface of the studs 10. In addition, the surrounding member 11 does not necessarily have to surround each individual stud 10 separately, and it may surround a plurality of studs 10 together.
[0062] However, when the filler 50 is placed in the joint portion 40, the flow of the filler 50 must not be obstructed by the surrounding member 11 and the filling of the filler 50 around the stud 10 must not be insufficient. That is, the surrounding member 11 needs to be configured so that the filler 50 can easily flow into the area around the stud 10 when the filler 50 is placed in the joint portion 40. Specific examples of the surrounding member 11 having such a configuration include, for example, the spiral bars illustrated in FIGS. 7, 8, and 9(a) and a substantially cylindrical member in which a plurality of annular reinforcing bars as illustrated in FIG. 9(b) are connected at intervals in the axial direction, and the like.
[0063] That is, the third structure 103 further includes a surrounding member which is a cylindrical member provided with a gap on the side surface through which the filler before being cured can flow from the outside to the inside, and is any one of the first to third structures described above. In addition, the base end region, which is a region adjacent to the girder joint surface of at least some of the studs 10, is inserted inside the surrounding member 11.
[0064] In addition, the mode in which the stud 10 is inserted into the surrounding member 11 is not particularly limited. For example, the stud 10 may be inserted through an opening at an end portion in the axial direction of the surrounding member 11, or the stud 10 may be inserted through a gap provided on the side surface of the surrounding member 11. That is, the surrounding member 11 may be arranged such that the axial direction of the surrounding member 11 is parallel to the longitudinal direction of the stud 10 (that is, standing vertically), as in the third structure 103a illustrated in FIG. 10. Alternatively, the surrounding member 11 may be arranged such that the axial direction of the surrounding member 11 is orthogonal to the longitudinal direction of the stud 10 (that is, lying horizontally), as in the third structure 103b illustrated in FIG. 11. It should be noted that, similar to FIG. 4(b) referred to in the description of the second structure 102, in FIGS. 10(b) and 11(b) as well, for the purpose of facilitating the understanding of the present embodiment, a penetrating reinforcing bar 62 that exists at a position shifted in the bridge axis direction (x-axis direction) from the cross-sectional view and would not originally appear in the cross-section is drawn.
[0065] <Effect> In the third structure 103, due to the above configuration, it is possible to mitigate the concentration of stress caused by the displacement between the precast PC floor slab 30 and the girder 20 at the base of the stud 10. As a result, according to the third structure 103, it is possible to reduce the likelihood that the base of the stud 10 will become the starting point for deterioration and / or damage of the joint structure between the precast PC floor slab 30 and the girder 20.
[0066] As described above, for the purpose of explaining the content of the present disclosure, a plurality of embodiments having specific configurations have been described with reference to the accompanying drawings at times. However, the scope of the present disclosure should not be construed as being limited to these exemplary embodiments, and it goes without saying that appropriate modifications can be made within the scope of the matters described in the claims and the specification.
[0067] For example, the joint structure between the precast PC floor slab and the girder according to the present disclosure (the present disclosure structure) can be applied not only to the joint between the precast PC floor slab installed in place of the existing floor slab in the floor slab replacement work of a road or a bridge and the girder such as a steel girder, but also to the joint between the precast PC floor slab and the girder such as a steel girder in a newly constructed road or bridge.
Description of Reference Numerals
[0068] 101, 102, 103, 103a, 103b... Joint structures between precast PC floor slabs and girders, 10... Studs, 11... Surrounding members, 20... Girders, 30... Precast PC floor slabs, 40... Joint parts, 50, 51, 52... Filling materials, 60... Perforated steel plate shear connectors (PBLs), 61... Studs, 62... Penetrating reinforcing bars
Claims
1. A joint structure between a precast PC floor slab and a girder, wherein the precast PC floor slab includes at least a pair of perforated steel plate dowels installed so as to protrude from a floor slab joint surface which is a surface of the precast PC floor slab facing the girder, the girder includes at least one stud installed so as to protrude between the paired perforated steel plate dowels from a girder joint surface which is a surface of the girder facing the precast PC floor slab, the precast PC floor slab and the girder are connected via the perforated steel plate dowels and the stud by a filler poured into and cured in a joint portion which is a space between the precast PC floor slab and the girder. A joint structure between a precast PC floor slab and a girder, characterized by the above.
2. A joint structure between a precast PC floor slab and a girder according to Claim 1, further comprising a through bar which is a reinforcing bar inserted so as to span both of through holes respectively drilled in the paired perforated steel plate dowels in the joint portion. A joint structure between a precast PC floor slab and a girder, characterized by the above.
3. A joint structure between a precast PC floor slab and a girder according to Claim 2, wherein a plurality of the through holes are drilled in the paired perforated steel plate dowels in the joint portion, a plurality of the through bars are inserted into the plurality of the through holes, and the stud is positioned between the plurality of the through bars. A joint structure between a precast PC floor slab and a girder, characterized by the above.
4. A joint structure between a precast PC floor slab and a girder according to any one of Claims 1 to 3, further comprising an enclosing member which is a cylindrical member provided with a gap on a side surface through which the filler before being cured can flow from outside to inside, wherein a base end region which is a region adjacent to the girder joint surface of at least a part of the stud is inserted into the inside of the enclosing member. A joint structure between a precast PC floor slab and a girder, characterized by the above.