Bridge joint structure, cross beam, precast main girder and bridge jointing method

Abstract

To provide a bridge joint structure that ensures sufficient load-bearing performance in the direction perpendicular to bridge axis.SOLUTION: A bridge joint structure 100 includes a cross girder 1 that is installed on a substructure 3 via supports 4 and extends in a direction perpendicular to the bridge axis, and multiple precast main girders 2 that are installed on the cross girder 1 and extend in the bridge axis direction in parallel to the direction perpendicular to the bridge axis, and a shear key 6 is formed on the top surface of the cross girder 1 to prevent the multiple precast main girders 2 from shifting due to shear force. The jointing method includes a cross girder installation process to install the cross girder 1 on the substructure so that the surface with the shear key 6 becomes the girder top surface, and a main girder installation process to install the multiple precast main girders 2 on the cross girder 1 so that the shear keys 6 prevent them from shifting due to shear force.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bridge joint structure, a cross beam, a precast main girder, and a bridge joint method. [Background technology]

[0002] Currently, research is being conducted on bridge joint structures. A new chapter, "Chapter 7: Joints," was added to "III. Concrete Bridges and Concrete Members" of the Highway Bridge Specifications and Commentary (hereinafter referred to as "Highway Specifications"), which was revised in July 2017, indicating the need to specifically clarify the load-bearing performance of bridge joints. Regarding the load-bearing performance of joints in conventional bridges, although the load-bearing mechanism against loads in the bridge axis direction has been confirmed, the load perpendicular to the bridge axis has not been fully confirmed, and there has been a problem in that the load-bearing performance may not be sufficiently ensured.

[0003] Patent Document 1 discloses, as an example of a bridge having a joint, a joint structure of a bridge having cross beams and vertical beams, with the ends of each beam being integrated with cast-in-place concrete. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-256873 A Summary of the Invention [Problem to be solved by the invention]

[0005] According to the bridge joint structure disclosed in Patent Document 1, multiple vertical beams are erected in parallel on top of horizontal beams, which makes it possible to reduce the number of supports on the substructure. However, the bridge joint structure disclosed in Patent Document 1 does not disclose the load-bearing performance in the direction perpendicular to the bridge axis, and there is a problem in that the load-bearing performance in the direction perpendicular to the bridge axis cannot be sufficiently ensured.

[0006] The present invention was devised in consideration of the above-mentioned problems, and its object is to provide a bridge joint structure which ensures sufficient load-bearing performance in the direction perpendicular to the bridge axis. [Means for solving the problem]

[0007] The bridge joint structure in the first invention comprises a cross girder installed on the substructure via supports and extending perpendicular to the bridge axis, and a number of precast main girders installed on the cross girder and extending in the bridge axis direction in parallel perpendicular to the bridge axis, and is characterized in that a shear key is formed on the upper surface of the cross girder to prevent the precast main girders from shifting due to shear force.

[0008] The bridge joint structure of the second invention is characterized in that, in the first invention, it further includes a cross fastening section on the cross beam that connects and integrates multiple precast main girders together in a direction perpendicular to the bridge axis, and a shear key is formed between the cross beam and the cross fastening section.

[0009] The bridge joint structure of the third invention is the first or second invention, characterized in that the cross beam is provided with a reinforcing material that reinforces the shear key.

[0010] The bridge joint structure of the fourth invention is characterized in that, in the second invention, the cross beam and the cross fastening portion are provided with reinforcing materials that reinforce the shear key.

[0011] The cross girder in the fifth invention is a cross girder that is installed on the substructure via supports and is installed under a number of precast main girders that are parallel to the bridge axis and extend in the direction of the bridge axis, and is characterized in that a shear key is formed on the surface facing the precast main girder to prevent the precast main girder from shifting due to shear force.

[0012] The precast main girder in the sixth invention is a precast main girder that is installed on the substructure via supports and is installed on a cross girder extending perpendicular to the bridge axis, and is characterized in that the installation surface for installation on the cross girder is formed with a shear key to prevent the cross girder from shifting due to shear force.

[0013] The bridge joining method of the seventh invention is characterized by comprising a cross beam installation process in which a cross beam is orientated so that its longitudinal direction is perpendicular to the bridge axis and the surface having the shear key is the girder top surface, and installed on a substructure via supports, and a main girder installation process in which a number of precast main girders are installed on the cross beam installed by the cross beam installation process, in parallel in a direction perpendicular to the bridge axis, so that their longitudinal direction is in the bridge axis direction, and so that the shear keys prevent the precast main girders from shifting due to shear force.

[0014] The bridge joining method of the 8th invention is characterized in that, in the 7th invention, the main girder installation process includes installing a plurality of the precast main girders, and then pouring concrete in place on the cross girder installed in the cross girder installation process so that the plurality of precast main girders are in contact with the shear keys, thereby connecting and integrating the plurality of precast main girders in a direction perpendicular to the bridge axis. Effect of the Invention

[0015] According to the first to fourth inventions, a shear key is formed on the upper surface of the cross beam to prevent the precast main girders from shifting due to shear force. This makes it possible to obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0016] In particular, according to the second invention, a shear key is formed between the cross beam and the cross fastening part. Therefore, regardless of the installation position of the multiple main girders, it is possible to counter the shear force acting on the multiple precast main girders via the cross fastening part. This improves workability.

[0017] In particular, according to the third aspect of the present invention, the cross beam is provided with a reinforcing member that reinforces the shear key. This makes it possible to more reliably obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to more reliably ensure sufficient load-bearing capacity in the direction perpendicular to the bridge axis.

[0018] In particular, according to the fourth aspect of the present invention, the cross beam and the cross fastening portion are provided with reinforcing members that reinforce the shear keys. This makes it possible to more reliably obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to more reliably ensure sufficient load-bearing capacity in the direction perpendicular to the bridge axis.

[0019] According to the fifth aspect of the present invention, the cross girder has a shear key formed on the surface facing the precast main girder. This allows the bridge to obtain a shear strength higher than the ultimate strength. This ensures sufficient load-bearing capacity in the direction perpendicular to the bridge axis.

[0020] According to the sixth aspect of the present invention, the precast girder has a shear key formed on the installation surface for installation on the cross beam. This allows the bridge to obtain a shear strength higher than the ultimate strength. This ensures sufficient load-bearing capacity in the direction perpendicular to the bridge axis.

[0021] According to the seventh and eighth inventions, a girder installation process is included in which multiple precast main girders are installed on the cross beams so that the shear keys prevent the multiple precast main girders from shifting due to shear force. This makes it possible to obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0022] In particular, according to the eighth aspect of the present invention, the main girder installation process involves pouring concrete in place on the cross beam so that it contacts the precast main girder and the shear key, and connecting and integrating the multiple precast main girders in the direction perpendicular to the bridge axis. Therefore, regardless of the installation positions of the multiple precast main girders, the shear force acting on the multiple precast main girders can be resisted through the cross fastening parts, thereby improving workability. [Brief description of the drawings]

[0023] [Figure 1] 1(a) and 1(b) are schematic diagrams showing an example of a joint structure for a bridge in this embodiment, where FIG. 1(a) is a side view and FIG. 1(b) is a cross-sectional view taken along line AA of FIG. 1(a). [Diagram 2] 2(a) to 2(c) are schematic diagrams showing an example of a shear key formed between a cross beam and a cross fastening portion in this embodiment. [Diagram 3] 3(a) and 3(b) are schematic diagrams showing an example of a shear key formed between a cross beam and a cross fastening portion in this embodiment. [Figure 4] 4(a) and 4(b) are schematic diagrams showing a modified example of the joint structure of a bridge in this embodiment, where FIG. 4(a) is a side view and FIG. 4(b) is a BB cross-sectional view of FIG. 4(a). [Diagram 5] 5(a) to 5(c) are schematic diagrams showing an example of a shear key formed between a cross beam and a precast main girder in this embodiment. [Figure 6] FIG. 6 is a schematic diagram showing an example of a shear key formed between a cross beam and a precast main girder in this embodiment. [Figure 7] 7(a) to 7(c) are schematic diagrams showing the test conditions for the element test using a test specimen relating to the joint structure of a bridge in this embodiment. [Figure 8] FIG. 8 is a graph showing the test results of an example of the present invention and a comparative example regarding an element test using a test specimen related to the joint structure of a bridge in this embodiment. [Figure 9] FIG. 9 is a photograph showing the test results of an example of the present invention and a comparative example regarding an element test using a test specimen related to the joint structure of a bridge in this embodiment. [Figure 10] FIG. 10 is a graph showing the test results of an example of the present invention regarding an element test using a test specimen related to the joint structure of a bridge in this embodiment. [Figure 11]FIG. 11 is a graph showing test results of a comparative example regarding an element test using a test specimen related to the joint structure of a bridge in this embodiment. [Figure 12] FIG. 12 is a schematic diagram showing the test conditions of a full-scale test on the joint structure of a bridge in this embodiment. [Figure 13] FIG. 13 is a graph showing the test results of an example of the present invention regarding a full-scale test on a joint structure of a bridge in this embodiment. [Figure 14] FIG. 14 is a schematic diagram showing the test results of an example of the present invention regarding a full-scale test on a joint structure of a bridge in this embodiment. [Figure 15] FIG. 15 is a graph showing the test results of an example of the present invention regarding a full-scale test on a joint structure of a bridge in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an example of a bridge joint structure 100 as an embodiment of the present invention will be described in detail with reference to the drawings. Note that the configurations in each drawing are depicted diagrammatically for the purpose of explanation, and for example, the size of each component and the size comparison between components may differ from those in the drawings.

[0025] (Bridge joint structure 100) An example of a bridge joint structure 100 according to this embodiment will be described with reference to the drawings.

[0026] As shown in Figs. 1(a) and 1(b), the bridge joint structure 100 includes cross beams 1, 1' that are installed on substructures 3, 3' via supports 4, 4' and extend perpendicular to the bridge axis, and multiple precast main girders 2 that are installed on the cross beams 1, 1' and extend parallel to the bridge axis perpendicular to the bridge axis. The bridge joint structure 100 further includes cross fastening parts 5, 5' that connect and integrate the multiple precast main girders 2 on the cross beams 1, 1' in the direction perpendicular to the bridge axis. Since the bridge joint structure 100 installs multiple precast main girders 2 on a set of cross beams 1, 1' in parallel to the bridge axis perpendicular to the bridge axis, the number of supports can be reduced compared to the case where precast main girders are installed on substructures 3, 3' via supports 4, 4', and the construction man-hours and costs of the bridge can be reduced.

[0027] In the bridge joint structure 100, a shear key 6 may be formed between the cross beam 1 and the cross fastening portion 5, as shown in Fig. 1(b) and Fig. 2(a) to Fig. 2(c), for example. Furthermore, the bridge joint structure 100 may further include at least one of a reinforcement member 7 and a penetrating reinforcement member 8 for reinforcing the shear resistance of the shear key 6, as shown in Fig. 3, for example. Here, the horizontal interface between the cross beam 1 and its upper member is defined as a joint J.

[0028] In addition, since the cross beam 1', lower structure 3', support 4' and cross fastening portion 5' are components having the same configuration as the cross beam 1, lower structure 3, support 4 and cross fastening portion 5, respectively, detailed explanations are omitted.

[0029] <Horizontal beam 1> The cross girder 1 is, for example, a bridge girder made of a known concrete member. The cross girder 1 is installed on the substructure 3 via supports 4. The cross girder 1 extends in a direction perpendicular to the bridge axis. The cross girder 1 may be, for example, a cast-in-place girder, a precast concrete (PCa) girder, or a prestressed concrete (PC) girder.

[0030] The cross beam 1 has a cross section that is approximately inverted T-shaped when viewed perpendicular to the bridge axis, as shown in Fig. 1(a), for example. In this case, the cross beam 1 has, for example, a girder body 11 and a flange 12 that is widened in the bridge axis direction from the lower part of the girder body 11. The flange 12 may be widened from both sides of the girder body 11 in the bridge axis direction, or may be widened from either one side to have a cross section that is approximately L-shaped.

[0031] As shown in FIG. 1(b), for example, multiple precast main girders 2 are installed on the installation surface f1 of the surface of the flange 12 of the cross girder 1. A shear key 6 is provided on the installation surface f1, for example, in a space formed by the multiple precast main girders 2 and the flange 12. A cross tightening portion 5 is provided in the space so as to fit with the shear key 6. At this time, the shear key 6 is formed at the joint J. Details of the shear key 6 will be described later.

[0032] <Precast main girder 2> The precast main girder 2 is, for example, a known PCa girder produced in advance in a factory or the like. A plurality of precast main girders 2 are installed on the cross girder 1. A plurality of precast main girders 2 are arranged in parallel in the direction perpendicular to the bridge axis and extend in the bridge axis direction. The precast main girder 2 may be, for example, a PC girder.

[0033] The precast main girder 2 is a T-girder that is substantially T-shaped when viewed in cross section in the bridge axis direction, as shown in Fig. 1(b), for example. The precast main girder 2 is installed on the flange 12 of the cross girder 1 so that, for example, installation surface f2 contacts installation surface f1. The precast main girder 2 is installed, for example, with multiple girders spaced apart from each other and arranged in parallel in the direction perpendicular to the bridge axis, forming a space, and the multiple girders are integrated by cross fastening parts 5 provided in the space.

[0034] <Substructure 3> The substructure 3 supports the cross beam 1 from below. The substructure 3 is, for example, a known bridge pier.

[0035] <Support 4> The bearing 4 is provided on the substructure 3 and supports the cross beam 1 from below. The bearing 4 is a known bearing provided, for example, between the substructure and superstructure of a bridge.

[0036] <Side fastening part 5> The horizontal fastening parts 5 are, for example, cast-in-place concrete members. The horizontal fastening parts 5 are provided on the cross beams 1, and connect and integrate the multiple precast main girders 2 together in the direction perpendicular to the bridge axis.

[0037] The cross fastening portion 5 is cast in place so as to be in contact with a plurality of precast main girders 2 and a shear key 6 provided on the upper surface of the cross beam 1, as shown in FIG. 1(b), for example.

[0038] The material of the horizontal fastening portion 5 is, for example, a concrete member similar to that of the horizontal beam 1, and the horizontal fastening portion 5 is cast by solidifying known ready mixed concrete.

[0039] <Shear key 6> The shear key 6 is provided to prevent the precast main girder 2 from shifting horizontally due to shear force.

[0040] The shear key 6 is provided on the upper surface of the cross beam 1. Here, the upper surface refers to at least one of the upper surface of the girder body 11 of the cross beam 1 and the upper surface of the flange 12.

[0041] 1(b), the shear key 6 is provided on the upper surface of the flange 12. That is, the cross beam 1 has the shear key 6 formed on the surface facing the precast main girder 2.

[0042] Furthermore, multiple shear keys 6 may be provided along the direction perpendicular to the bridge axis or along the bridge axis. In this case, even higher shear strength can be obtained, and the load-bearing performance in the direction perpendicular to the bridge axis can be further improved.

[0043] As shown in Figures 2(a) to 2(c), for example, the shear key 6 is composed of a first shear key 61 formed in advance on the cross beam 1, and a second shear key 62 formed on the surface of the cast-in-place cross fastening part 5. In this case, it is possible to resist the shear force acting on the multiple precast main girders 2 via the cross fastening part 5, regardless of the installation positions of the multiple precast main girders 2. This can improve workability.

[0044] 2(a), the shear key 6 has a structure in which a first convex shear key 61a provided on the flange 12 is fitted into a second concave shear key 62a formed to match the shape of the first shear key 61a. Here, the first shear key 61a has a shape that protrudes from, for example, the installation surface f1 of the flange 12.

[0045] 2(b), the shear key 6 may have a structure in which a concave first shear key 61b provided on the flange 12 is fitted into a convex second shear key 62b formed to match the shape of the first shear key 61b. Here, the first shear key 61b has a shape recessed from the installation surface f1 of the flange 12, for example.

[0046] 2(c), the shear key 6 may have a structure in which one or more convex first shear keys 61a and one or more concave first shear keys 61b are alternately adjacent to each other and fitted into the second shear keys 62a and the second shear keys 62b, respectively. In other words, the joint J, which is the interface between the first shear key 61 and the second shear key 62, may have a zigzag cross section.

[0047] The shape of the shear key 6 may be, for example, a generally trapezoidal shape in cross section, a generally triangular shape in cross section, or a generally rectangular shape in cross section. The dimensions of the shear key 6 are, for example, as shown in FIG. 3(b), a width w1 of the trapezoid upper side in cross section is about 60 mm, a width w2 of one trapezoid oblique side in the direction perpendicular to the bridge axis is about 60 mm, a width w3 of the other trapezoid oblique side in the direction perpendicular to the bridge axis is about 60 mm, and a width w4 of the trapezoid height is about 60 mm. Also, for example, a width w5 of the gap between adjacent shear keys is about 60 mm. Also, an angle of the shear key 6 is, for example, 45° with respect to the horizontal direction.

[0048] <Reinforcement material 7> As shown in FIG. 3(a), for example, the reinforcing member 7 is provided along the shape of the shear key 6 (shape of the joint J) in order to reinforce the shear resistance of the shear key 6. In this case, it is possible to obtain a shear resistance higher than the ultimate strength of the bridge. This makes it possible to ensure sufficient load resistance in the direction perpendicular to the bridge axis. Details of the load resistance will be explained in the examples below.

[0049] 3(b), the reinforcement 7 is a rod-shaped reinforcement bent at approximately 90° to form a generally L-shape, and one reinforcement 7 is installed for each shear key 6. The reinforcement 7 includes, for example, at least one of a reinforcement 7a provided on the flange 12 of the cross beam 1 and a reinforcement 7b provided on the horizontal fastening portion 5. Note that the reinforcement 7a may be embedded inside the cross beam 1, or at least a part of it may be exposed from the cross beam 1, as long as the reinforcement 7a is disposed in such a way that it can prevent the precast main girder 2 from shifting due to shear force.

[0050] The reinforcement 7a is provided, for example, along the shape of the convex first shear key 61a and the concave first shear key 61b. Here, the reinforcement 7a is installed on the surface or near the surface of the face facing the precast main girder 2, with both ends of the rod facing downward at 45° with respect to the horizontal direction. When the reinforcement 7a is provided along the shape of the convex first shear key 61a, the upwardly facing bent portion protrudes toward the side of the horizontal fastening portion 5 based on the height of the joint J without the shear key 6. In this case, the reinforcement 7a can resist the horizontal load from the horizontal fastening portion 5, and a higher shear resistance can be obtained. This can further improve the load-bearing performance in the direction perpendicular to the bridge axis. Note that the reinforcement 7a may be embedded inside the cross beam 1, or at least a part of it may be exposed from the cross beam 1, as long as it is arranged to prevent the horizontal fastening portion 5 from being displaced by the shear force.

[0051] The reinforcement 7b is provided along the shape of the concave second shear key 62a and the convex second shear key 62b. Here, the reinforcement 7b is installed so that both ends of the rod are directed upward at 45° with respect to the horizontal direction. When the reinforcement 7b is provided along the shape of the concave second shear key 62a, the bent portion facing downward protrudes toward the cross beam 1 side based on the height of the tip of the first shear key 61a. In this case, the reinforcement 7a can resist the horizontal load from the cross beam 1, and a higher shear strength can be obtained. This can improve the load-bearing performance in the direction perpendicular to the bridge axis. The reinforcement 7b may be embedded inside the cross fastening portion 5, or at least a part of it may be exposed from the cross fastening portion 5, as long as it is arranged to prevent the cross beam 1 from being displaced by the shear force.

[0052] Furthermore, when the reinforcing member 7a is provided along the shape of the concave first shear key 61b, the upwardly bent portion protrudes toward the lateral fastening portion 5 with the height of the tip of the convex second shear key 62b as the reference. In this case as well, the reinforcing member 7a can resist the horizontal load from the lateral fastening portion 5, and a higher shear resistance can be obtained.

[0053] Furthermore, when the reinforcement 7b is provided along the shape of the convex second shear key 62b, the downward bent portion protrudes toward the cross beam 1 side based on the height of the joint J without the shear key 6. In this case as well, the reinforcement 7b can resist the horizontal load from the cross beam 1, and a higher shear resistance can be obtained.

[0054] In addition, by providing both reinforcement members 7a and 7b, the cross beam 1 and the cross fastening portion 5 support each other horizontally via each reinforcement member 7a, 7b, and can resist shear forces, thereby further improving the load-bearing performance perpendicular to the bridge axis.

[0055] As the material for the reinforcing material 7, for example, known reinforcing bars for reinforced concrete may be used, or known non-ferrous materials such as carbon fiber cables (CFCC) and carbon fiber reinforced plastics (CFRP) may be used.

[0056] <Penetration reinforcement material 8> The penetrating reinforcement 8 is provided to penetrate the shear key 6 in order to reinforce the shear resistance of the shear key 6, as shown in FIG. 3(a), for example. The penetrating reinforcement 8 is provided, for example, by projecting from the cross beam 1 and then casting the cross fastening part 5 in place, so that the penetrating reinforcement 8 penetrates the shear key 6. For example, one or more penetrating reinforcement members 8 are provided. In this case, compared to the case where the cross beam 1 and the cross fastening part 5 are installed and then a reinforcement that penetrates them is installed, there is no need to perform the work of drilling holes to provide insertion holes for the reinforcement. This can improve workability.

[0057] The penetrating reinforcement 8 is provided in an area where the convex first shear keys 61a formed on the installation surface f1 of the flange 12 are not provided, as shown in FIG. 3(b), for example. The penetrating reinforcement 8 is provided, for example, in an area R between adjacent first shear keys 61a. In this case, it is easy to protrude the penetrating reinforcement 8 without damaging the reinforcement 7a. This can improve workability.

[0058] As the material for the penetrating reinforcement member 8, for example, a known steel bar similar to that of the reinforcement member 7 may be used, or a known non-ferrous material such as a carbon fiber cable or carbon fiber reinforced plastic may be used.

[0059] (Modification of bridge joint structure 100) A modified example of the bridge joint structure 100 in this embodiment will be described with reference to the drawings.

[0060] <Precast main girder 2> The precast main girder 2 is a hollow girder that is substantially square-shaped when viewed in cross section in the bridge axis direction, as shown in Figures 4(a) and 4(b). The precast main girder 2 has a shear key 6 formed at the interface between the installation surface f2 and the installation surface f1, for example.

[0061] That is, the precast main girder 2 has a shear key 6 formed on the installation surface f2 for installation on the cross girder to prevent the cross girder from shifting due to shear force. In addition, the precast main girder 2 may have a reinforcing material (not shown) provided on the installation surface f2 along the shape of the shear key 6 (shape of the joint J) in order to reinforce the shear resistance of the shear key 6, similar to the above-mentioned reinforcing materials 7a and 7b. In this case, a shear resistance higher than the ultimate strength of the bridge can be obtained. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0062] Furthermore, by using a precast main girder 2 with a shear key 6 formed on the installation surface f2, it is possible to obtain a shear strength higher than the ultimate strength even for bridges that use cast-in-place cross girders 1, thereby improving the load-bearing performance perpendicular to the bridge axis.

[0063] <Shear key 6> As shown in Fig. 5(a) to Fig. 5(c), for example, the shear key 6 is composed of a first shear key 61 formed in advance on the cross beam 1 and a third shear key 63 formed in advance on the precast main girder 2. In this case, the installation positions of the multiple precast main girders 2 can be easily specified using the position of the first shear key 61 as a guide, thereby improving workability.

[0064] 5(a), the shear key 6 has a structure in which a first convex shear key 61a provided on the flange 12 is fitted into a third concave shear key 63a formed in advance to match the shape of the first shear key 61a. Here, the third shear key 63a has a shape recessed below the installation surface f2 of the precast main girder 2, for example.

[0065] 5(b), the shear key 6 may have a structure in which a concave first shear key 61b provided on the flange 12 is fitted into a convex third shear key 63b formed in advance to match the shape of the first shear key 61b. Here, the third shear key 63a has a shape that protrudes from, for example, the installation surface f2 of the precast main girder 2.

[0066] 5(c), the shear key 6 may have a structure in which one or more convex first shear keys 61a and one or more concave first shear keys 61b are alternately adjacent to each other and fitted into the third shear keys 63a and the third shear keys 63b, respectively. In other words, the joint J, which is the interface between the first shear key 61 and the third shear key 63, may have a zigzag cross section.

[0067] <Reinforcement material 7> The reinforcing material 7 may include a reinforcing material 7c provided on the precast main girder 2, as shown in Fig. 6, for example. The reinforcing material 7c may be embedded inside the precast main girder 2, or at least a part of it may be exposed from the precast main girder 2, so long as the arrangement can prevent the precast main girder 2 from shifting due to shear force. Note that Fig. 6 illustrates a T-shaped precast main girder 2, but the same can be applied to a hollow girder precast main girder 2.

[0068] When the reinforcement 7c is provided along the shape of the convex third shear key 63b, as shown in Fig. 6 for example, both ends of the rod are installed facing 45° upward from the horizontal. When the reinforcement 7c is provided along the shape of the convex third shear key 63b, for example, the bent portion facing downward protrudes toward the cross beam 1 side based on the height of the joint J where there is no shear key 6. In this case as well, the reinforcement 7c can resist the horizontal load from the cross beam 1, and a higher shear resistance can be obtained.

[0069] Furthermore, when reinforcement 7c is provided along the shape of the concave third shear key 63a, for example, both ends of the rod are installed facing downward at 45° from the horizontal direction. When reinforcement 7c is provided along the shape of the concave second shear key 62a, the downward bent portion protrudes toward the cross beam 1 using the height of the tip of the first shear key 61a as the reference. In this case as well, reinforcement 7c can resist the horizontal load from the cross beam 1, and a higher shear resistance can be obtained.

[0070] In addition, by providing both reinforcement members 7a and 7c, the cross beam 1 and the precast main girder 2 support each other horizontally via each reinforcement member 7a, 7c, and can resist shear forces, thereby further improving the load-bearing performance perpendicular to the bridge axis.

[0071] <Penetration reinforcement material 8> The penetrating reinforcement 8 may be, for example, a core material 9 for reinforced concrete made of reinforcing bars arranged inside the precast main girder 2. This allows the entire precast main girder 2 to resist shear forces via the penetrating reinforcement 8.

[0072] (Joining method for bridge joint structure 100) Next, an example of a bridge joining method will be described as a construction method for the bridge joint structure 100 in this embodiment.

[0073] The bridge joining method includes, for example, a cross beam installation process and a main girder installation process.

[0074] <Horizontal girder installation process> In the cross beam installation process, the worker orients the cross beam 1 so that its longitudinal direction is perpendicular to the bridge axis and the surface having the first shear key 6a is the girder upper surface, and installs it on the substructure 3 via the support 4. That is, the worker installs the cross beam 1 with the installation surface f1 of the cross beam 1 facing upward.

[0075] Also, the worker may install the cross beam 1 on which the reinforcing material 7a is provided in advance along the shape of the first shear key 6a.

[0076] <Main girder installation process> In the main girder installation process, workers install multiple precast main girders 2 on the cross girder 1 installed in the cross girder installation process. At this time, the multiple precast main girders 2 are installed in parallel in the direction perpendicular to the bridge axis, with their longitudinal direction in the bridge axis direction, and the multiple precast main girders 2 are installed so that they are prevented from shifting due to shear force by the first shear key 6a. The first shear key 6a installed in the cross girder installation process may include a reinforcing material 7a. In other words, the multiple precast main girders 2 may be installed so that they are prevented from shifting due to shear force by the reinforcing material 7a included in the first shear key 6a. In this case, a shear strength higher than the ultimate strength can be obtained for the bridge. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0077] Here, the multiple precast main girders 2 may transmit shear force to the first shear key 6a through the lateral fastening parts 5. In this case, after installing the multiple precast main girders 2, as shown in FIG. 1(b), for example, in the main girder installation process, concrete is cast in place so as to contact the multiple precast main girders 2 and the first shear key 6a to form the lateral fastening parts 5, and the multiple precast main girders 2 are connected and integrated in the direction perpendicular to the bridge axis. At this time, a shear key 6 is formed at the joint J. In this case, the shear force acting on the multiple precast main girders 2 can be resisted through the lateral fastening parts 5 regardless of the installation positions of the multiple precast main girders 2. This can improve workability.

[0078] In addition, in the main girder installation process, the worker may install the penetrating reinforcement 8 before pouring the concrete in place. That is, the worker may install the penetrating reinforcement 8 so that it protrudes from the cross girder 1, and then pour concrete in place so that it contacts the penetrating reinforcement 8, the multiple precast main girders 2, and the first shear key 6a to form the cross tightening portion 5. In this case, the penetrating reinforcement 8 can resist the shear force.

[0079] As a method of installing the penetrating reinforcement 8, a worker may install a cross beam 1 having an insertion hole for inserting the penetrating reinforcement 8 in a cross beam installation process. In this case, the insertion hole for inserting the penetrating reinforcement 8 is provided in the region R between the first shear keys 61a on the surface of the cross beam 1, so that it is easy to ensure a space for providing the insertion hole without damaging the reinforcement 7a. This can improve manufacturability.

[0080] In addition, in the main girder installation process, the worker may install the reinforcement 7b before pouring the concrete in place. That is, as shown in FIG. 3(b), the worker may fix the reinforcement 7b to the penetrating reinforcement 8 so that it is aligned with the first shear key 61, and then pour the concrete in place to form the lateral fastening portion 5. In this case, the shear force can be reliably transmitted to the reinforcement 7b via the penetrating reinforcement 8. This makes it possible to further secure the load-bearing performance in the direction perpendicular to the bridge axis. The reinforcement 7b may be attached and fixed to a core material made of reinforcing bars (not shown) that is arranged in advance to construct the reinforced concrete structure of the lateral fastening portion 5.

[0081] (Modification of the joining method of the bridge joint structure 100) The multiple precast main girders 2 may directly transmit shear force to the shear key 6. In this case, as shown in, for example, Fig. 4(b) and Fig. 5(a) to Fig. 5(c), the worker constructs the shear key 6 by installing the multiple precast main girders 2 so that the first shear key 61 and the third shear key 63 fit together. At this time, the shear key 6 is formed at the joint J. After that, concrete may be poured in place to form the lateral fastening portion 5 so that the multiple precast main girders 2 are connected and integrated in a direction perpendicular to the bridge axis.

[0082] In addition, in the main girder installation step, the worker may install the precast main girder 2 on which the reinforcing member 7c is provided in advance along the shape of the third shear key 63b. In this case, the worker may install the precast main girder 2 so that the third shear key 63 on which the reinforcing member 7c is provided fits into the first shear key 61 on which the reinforcing member 7a is provided.

[0083] By carrying out the above-mentioned steps, the joining method for the bridge joint structure 100 is completed.

[0084] According to this embodiment, a shear key 6 is formed on the top surface of the cross beam 1 to prevent the precast main girders 2 from shifting due to shear force. This makes it possible to obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0085] Moreover, according to this embodiment, a shear key 6 is formed between the cross beam 1 and the cross fastening portion 5. Therefore, regardless of the installation positions of the multiple precast main girders 2, it is possible to resist the shear force acting on the multiple precast main girders 2 via the cross fastening portion 5. This can improve workability.

[0086] According to this embodiment, the cross beam 1 has a shear key 6 formed on the surface facing the precast main girder 2. This makes it possible to obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0087] According to this embodiment, the precast main girder 2 has a shear key 6 formed on the installation surface f2 for installation on the cross beam. This makes it possible to obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0088] In addition, according to this embodiment, a girder installation process is provided in which multiple precast main girders 2 are installed on the cross beam 1 so that the multiple precast main girders 2 are prevented from shifting due to shear force by the first shear key 6a. This makes it possible to obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0089] According to this embodiment, the main girder installation process involves pouring concrete in place on the cross beam 1 so that it contacts the precast main girders 2 and the shear keys 6, and connecting and integrating the multiple precast main girders 2 in a direction perpendicular to the bridge axis. This makes it possible to block the shear force acting on the multiple precast main girders 2 via the cross fastening parts 5, thereby improving workability. EXAMPLES

[0090] The following describes the results of an experiment on the effect of the joint structure of a bridge when the above-mentioned embodiment is used. In this experiment, for a joint cross girder in which multiple cross girders are joined, an element test was carried out focusing on the joint J (interface between the cross girder 1 and the cross fastening part 5) of the joint cross girder between the cross girder 1 and the cross fastening part 5, with the aim of confirming that the cross girder behaves as a single unit even if the bending fracture load is exceeded. In addition, a full-scale load test was also carried out focusing on the joint J (interface between the cross girder 1 and the precast main girder 2) between the cross girder 1 and the cross fastening part 5 and between the cross girder 1 and the main girder 2. Note that concrete members were used for all members. Also, known reinforcing bars for reinforced concrete were used for the reinforcement members 7 and the penetrating reinforcement members 8.

[0091] As a criterion for the experiment, for the joints, referring to Chapter 11 of Volume III of the Road Specifications, the load that would reach the characteristic value of the joint's limit state 1 (not exceeding the limit value of the yield displacement) was calculated, and then the bending fracture strength was designed to exceed this, and one of the criterions was to confirm that the load-bearing performance was equal to or greater than the design bending fracture strength. Also, regarding whether or not the joints behave as one unit, according to "Research on the Joint Surface of Concrete Composite Beams, Prestressed Concrete, Ototo et al., 9-2, pp8-18, 1967," there is research showing that if the displacement (horizontal displacement) of the joint when the girder is bent is 0.05 mm or less, then the upper and lower members behave as one unit, and this was used as a reference.

[0092] <Elemental Test> The characteristics of the test specimens used in the element tests are as shown in [Table 1]. The example of the present invention is a jointed cross beam in which the cross beam is divided into upper and lower parts, and has a joint between the cross beam 1 and the cross tightening part 5. In addition, the joint has a shear key 6, a reinforcement 7, and a penetrating reinforcement 8. Comparative Example 1 is an integral cross beam in which the cross beam is not divided into upper and lower parts, and has no joint. Comparative Example 2 is a jointed cross beam in which the cross beam is divided into upper and lower parts like the example of the present invention, and has a joint between the upper cross beam and the lower cross beam, but does not have a shear key 6, a reinforcement 7, or a penetrating reinforcement 8 at the joint.

[0093] [Table 1]

[0094] The divided surfaces of the present invention example and the comparative example 2 were both subjected to a washout treatment. The angle of the shear key 6 of the present invention example was 45°, and the shape was adjusted so that the cross-sectional area of ​​the reinforcement 7 at the joint was 0.25% of the joint surface area of ​​the concrete at the joint. The load at which the joint reached the characteristic value of limit state 1 was set to 300 kN, and the load at which the cross beam reached the bending fracture strength was set to 453 kN.

[0095] The shape of the present invention is as shown in Fig. 7(a). The dimensions of the joint cross beam are a rectangular parallelepiped with a width of 2250 mm, a height of 450 mm, and a depth of 200 mm. In addition, as shown in Fig. 7(a), the joint cross beam was equipped with five displacement gauges (D-1, D-2, D-3, D-4, D-5) for measuring the displacement of the entire cross beam, five displacement gauges (DH-1, DH-2, DH-3, DH-4, DH-5) for measuring the horizontal displacement at the joint, and five displacement gauges (DV-1, DV-2, DV-3, DV-4, DV-5) for measuring the vertical displacement at the joint. A high-sensitivity displacement gauge CDP-50 was used as the displacement gauge.

[0096] The shape of Comparative Example 1 is as shown in Fig. 7(b). The dimensions of the integral cross beam are the same as those of Inventive Example 1. In addition, as shown in Fig. 7(b), five displacement gauges (D-1, D-2, D-3, D-4, and D-5) were installed on the integral cross beam to measure the displacement of the entire cross beam. The displacement gauges used were the same as those in Inventive Example 1.

[0097] The shape of Comparative Example 2 is as shown in FIG. 7(c). The dimensions of the joint cross beam are the same as those of Example 1 of the present invention. In addition, as shown in FIG. 7(c), a displacement meter was installed in the joint cross beam at the same position as that of Example 1 of the present invention. The displacement meter used is the same as that of Example 1 of the present invention. The solid line grids shown in FIG. 7(a) to FIG. 7(c) indicate the position of reinforcing bars for reinforced concrete. Specifically, the test specimen shown in FIG. 7(a) has reinforcing bars in a grid pattern, including penetrating reinforcement 8 that penetrates the joint J in the vertical direction and non-penetrating reinforcing bars that do not penetrate the joint J in the vertical direction. In addition, the test specimen shown in FIG. 7(b) has reinforcing bars arranged in a grid pattern almost entirely. In addition, in the test specimen shown in FIG. 7(c), reinforcing bars are arranged in a grid pattern in the lower cross beam corresponding to the cross beam 1 and the upper cross beam corresponding to the horizontal tightening portion 5, but reinforcing bars corresponding to the penetrating reinforcement 8 that penetrates the upper cross beam and the lower cross beam while penetrating the joint in the vertical direction are not provided in the joint.

[0098] As shown in the schematic diagram of the specimen of the present invention in Fig. 7(a), the load was applied from above at two points 975 mm from both ends of the 2250 mm width while supporting from below at two points 100 mm from both ends of the 2250 mm width when viewed in the bridge axis direction. The same method of loading was used for the specimens of the comparative examples in Fig. 7(b) to 7(c).

[0099] As the test results of the element test, the load-displacement curves of the example of the present invention and each of the comparative examples are shown in Fig. 8. Graph D1 shows the load-displacement curve of the example of the present invention, graph D2 shows the load-displacement curve of the comparative example 1, and graph D3 shows the load-displacement curve of the comparative example 2, respectively.

[0100] According to FIG. 8, it was confirmed that the graph D1 (example of the present invention) and the graph D2 (comparative example 1) show almost the same load-displacement curve. In detail, the upper lateral fastening portion 5 of the example of the present invention failed under bending compression at a load of 532 kN, and the comparative example 1 failed under bending compression at a load of 514 kN. This value exceeds the load of 300 kN at which the shear strength of the joint reaches the characteristic value of the limit state 1, and the load of 453 kN at which the design bending fracture strength (ultimate strength) of the test specimen is reached. In other words, according to the joint cross beam of the example of the present invention, as with the integral cross beam of comparative example 1, it is possible to obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0101] 9(a) to 9(c) show external photographs showing the fracture modes of the present invention, comparative example 1, and comparative example 2. As shown in FIG. 9(a) for the present invention, a large crack occurred in region R1 of the specimen, and bending cracks were confirmed near the center. As shown in FIG. 9(b) for comparative example 1, a large crack occurred in region R2 of the specimen, and bending cracks were confirmed near the center. As shown in FIG. 9(c) for comparative example 2, fine cracks occurred along the joint surface in region R3 of the specimen, and shear cracks were confirmed in the diagonal direction from the end toward the position where the load was applied. That is, it was confirmed that the present invention and comparative example 1 had similar cracks, and that the cracks were different from those in comparative example 2. From these load-displacement curves and the crack occurrence state, it is considered that the joint cross beam of the present invention has the same fracture mode as the integral cross beam of comparative example 1.

[0102] On the other hand, in graph D3 (Comparative Example 2), the upper cross girder failed under bending compression at a load of 453 kN. This is equivalent to the load of 453 kN at which the test specimen's design bending failure strength (ultimate strength) is reached. In other words, with the joint cross girder of Comparative Example 2, the bridge cannot obtain a shear strength higher than the ultimate strength, and the load-bearing performance in the direction perpendicular to the bridge axis cannot be improved.

[0103] As described above, it was confirmed that Comparative Example 2 had cracks different from those in the present invention and Comparative Example 1. In particular, it was confirmed that Comparative Example 2 had more cracks and shear cracks in the joints than the present invention and Comparative Example 1. From these load-displacement curves and crack occurrence conditions, it is believed that the joint cross beam of Comparative Example 2 has a different failure mode from the joint cross beam of the present invention and the integral cross beam of Comparative Example 1.

[0104] 10 shows the load-displacement curve for the horizontal displacement of the joint of the example of the present invention, and FIG 11 shows the load-displacement curve for the horizontal displacement of the joint of the comparative example 2. The horizontal displacement of both the example of the present invention and the comparative example 2 was below -0.05mm to 0.05mm, and it can be said that they behaved as one. According to the measurement results of DV-1 to DV-5, almost no vertical displacement occurred, so it is not described here.

[0105] <Full-scale test> The test specimen used in the full-scale test was a jointed cross beam having a joint between a cross beam 1 and a cross fastening portion 5, and having a shear key 6 and a reinforcement 7 at the joint, similar to the characteristics of the example of the present invention in [Table 1].

[0106] The dividing surface of the joint was subjected to a washout process in the same way as in the element test. The angle of the shear key 6 was set to 45°, the same as in the present invention example in [Table 1], and the shape was adjusted so that the cross-sectional area of ​​the reinforcement 7 at the joint was 0.15% of the concrete joint surface area, referring to Chapter 11 of Part III of the Road Designation (0.20% or less). The load at which the joint reaches the characteristic value of limit state 1 was set to 5022kN, and the load at which the cross beam reaches the bending fracture strength was set to 5983kN.

[0107] The shape of the present invention is assumed to be the cross beam of a pretensioned T-girder bridge, as shown in FIG. 12. The shape of the joint cross beam is an approximately rectangular parallelepiped with a width of 6000 mm, a height of 1200 mm, and a depth of 1500 mm. In addition, as shown in FIG. 12(a), the joint cross beam was equipped with seven displacement gauges (D-1, D-2, D-3, D-4, D-5, D-6, D-7) for measuring the displacement of the entire cross beam, five displacement gauges (DH-1, DH-2, DH-3, DH-4, DH-5) for measuring the horizontal displacement at the joint, and five displacement gauges (DV-1, DV-2, DV-3, DV-4, DV-5) for measuring the vertical displacement at the joint. A high-sensitivity displacement gauge CDP-50 was used as the displacement gauge.

[0108] The shape of the cross beam 1 is the same as that shown in Fig. 1, with the girder body 11 being an approximately rectangular parallelepiped with a width of 6000 mm, a height of 800 mm, and a depth of 600 mm. The flanges 12 extend from the lower part of the girder body 11 on both sides by 450 mm, and the flanges 12 are 6000 mm wide and 300 mm high.

[0109] The shape of the precast main girder 2 is the same as in Figure 1, with the flange part having a width of 800 mm, a height of 900 mm, and a depth of 400 mm above the flange 12 on one side. For the precast main girder 2, the type "BS18" described in "Recommended Specifications B-1 Table 1 - Types of slab bridge girders and bending crack resistance" of JIS A 5373:2016 (precast prestressed concrete products) was used.

[0110] As a result of the full-scale test, the load-displacement curve of the example of the present invention is shown in Figure 13. According to Figure 13, when the load reached 6000kN, which exceeded the load of 5022kN, which is the characteristic value of the limit state 1 of the shear force of the joint, and the load of 5983kN, which is the design bending fracture strength (ultimate strength) of the test specimen, the steel of the load test device reached yield strain, so the loading test was terminated for safety reasons. In other words, the joint cross girder of the example of the present invention can obtain a shear strength higher than the ultimate strength of the bridge. This makes it possible to ensure sufficient load-bearing performance in the direction perpendicular to the bridge axis.

[0111] The appearance of the bridge joint structure 100 of the example of the present invention after the final load was applied is as shown in Figure 14. The thick lines in Figure 14 indicate the main crack locations. According to Figure 14, the cracks in the test specimen of the example of the present invention occurred near the joint surface between the precast main girder 2 and the lateral fastening portion 5, and there were almost no cracks along the joints between the cross beam 1 and the precast main girder 2, and between the cross beam 1 and the lateral fastening portion 5, or diagonal shear cracks.

[0112] Figure 15 shows the load-displacement curve for the horizontal displacement of the joint of the example of the present invention. For DH-3, the displacement was measured at a position equivalent to the center of the span in the bridge, but since this was a location where displacement due to shear slip did not occur, it is not shown here. According to Figure 15, the horizontal displacement was less than -0.05mm to 0.05mm, and it can be said that the specimens behaved as one. Note that the parts of DH-1 and DH-5 where the displacement is less than -0.05mm or more than 0.05mm are measured values ​​after the load was removed after the fracture load of 5983kN was reached, and do not have any effect on the load-bearing capacity of the specimens.

[0113] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0114] 100 Bridge joint structure 1, 1' transverse beam 11 digits main body 12 Flange 2 Multiple precast girders 3, 3' substructure 4, 4' bearing 5, 5' Side fastening section 6 Shear Key 61 First shear key 62 Second shear key 63 3rd shear key 7 Reinforcement 8 Penetrating reinforcement f1 (cross beam 1) installation surface f2 (Multiple precast girder 2) installation surface D1 (Example of the present invention) Load-displacement curve D2, D3 (Comparative example) Load-displacement curves Joint J

Claims

1. A cross girder that is installed on the substructure via a support and extends perpendicular to the bridge axis; A plurality of precast main girders are installed on the cross beam and extend in the bridge axis direction in parallel with each other in the direction perpendicular to the bridge axis; Equipped with A shear key is formed on the upper surface of the cross beam to prevent the precast main girders from shifting due to shear force. A bridge joint structure characterized by the above.

2. Further provided is a transverse fastening portion that connects and integrates the plurality of precast main girders together in a direction perpendicular to the bridge axis on the cross beam, The shear key is formed between the cross beam and the cross fastening portion.

2. The bridge joint structure according to claim 1 .

3. The cross beam is provided with a reinforcing member for reinforcing the shear key.

3. The bridge joint structure according to claim 1 or 2, characterized in that

4. The cross beam and the cross fastening portion are provided with a reinforcing material that reinforces the shear key.

3. The bridge joint structure according to claim 2 .

5. A cross girder is installed on the substructure via supports and under multiple precast main girders that are parallel to the bridge axis and extend in the bridge axis direction, A shear key is formed on the surface facing the precast main girder to prevent the precast main girder from shifting due to shear force. A cross girder characterized by:

6. A precast main girder is installed on a cross girder that is installed on the substructure via a support and extends perpendicular to the bridge axis, The installation surface for installation on the cross beam is formed with a shear key to prevent the cross beam from shifting due to shear force. A precast main girder characterized by:

7. a cross beam installation process in which the cross beam is oriented so that its longitudinal direction is perpendicular to the bridge axis and the surface having the shear key is the girder top surface, and is installed on the substructure via a support; a main girder installation process for installing multiple precast main girders on the cross beam installed in the cross beam installation process in such a way that the longitudinal direction of the precast main girders is in the bridge axis direction, parallel to the direction perpendicular to the bridge axis, and the multiple precast main girders are prevented from shifting due to shear force by the shear keys; Having A bridge joining method characterized by the above.

8. In the main girder installation process, after installing the multiple precast main girders, concrete is poured in place on the cross beam installed in the cross beam installation process so as to contact the multiple precast main girders and the shear key, and the multiple precast main girders are connected and integrated in a direction perpendicular to the bridge axis.

8. The bridge joining method according to claim 7, further comprising the steps of:

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