Joint Structure

Abstract

To provide a joint structure or the like capable of achieving a compact joint.SOLUTION: A joint structure 10 is a lap joint in which a pair of main steel members 1 having unevenness on the surface are arranged to overlap each other so that the axial directions are parallel to each other, and concrete C is filled between the main steel members 1. In the joint structure 10, a cover member 3 is disposed on the cover side of the main steel member 1. The cover member 3 has a bottom plate 31 disposed on the cover side of the main steel member 1, and a protruding part 32 that protrudes from the bottom plate 31 toward the main steel member 1 and is disposed on a side of the main steel member 1.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a joint structure. [Background technology]

[0002] RC (reinforced concrete), SRC (steel reinforced concrete), and SC (steel reinforced concrete) structures are structures that use reinforcing bars and steel materials as concrete reinforcement. Reinforcing bars and steel materials can reinforce concrete, which is weak in tension, by bearing the tensile stress when an external force is applied to the member, and can give the member bending and shear strength.

[0003] When constructing these structures, it is necessary to form joints between rebars and steel materials from a construction perspective. In RC structures, the joints between rebars are often mechanical joints, but when using large diameter or high strength rebars, the joints become long, which poses challenges in design and construction. In SC structures, just like RC structures, work is required to join steel materials, but these joints are generally welded or bolted, which poses challenges in construction and costs.

[0004] On the other hand, there are also examples of lap joints in which a pair of reinforcing bars or steel materials are placed in parallel on top of each other and stress is transmitted between these reinforcing bars or steel materials via concrete (see, for example, Patent Document 1), which are considered to be rational in terms of construction, etc., and effective as they easily absorb construction errors. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6375079 Summary of the Invention [Problem to be solved by the invention]

[0006] In lap joints, the unevenness of the surface of the rebar or steel increases the adhesion of the concrete and improves stress transmission. However, when the tensile force (pulling force) acting on the rebar or steel increases, bond splitting occurs from the surface, and the degree of restraint of the uneven rebar or steel plate decreases, which reduces the bond stress of the concrete.

[0007] The bond strength of concrete in lap joints is determined through experiments etc. as a bond strength depending on conditions such as the surface shape of the rebar or steel material and the concrete strength. However, due to the bond splitting mentioned above, the potential of the bond strength cannot be fully utilized, which has been a challenge in realizing a compact joint with a short joint length.

[0008] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a joint structure etc. that can realize a compact joint. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the present invention provides a joint structure in which a pair of reinforcing materials having uneven surfaces are overlapped and arranged so that their axial directions are parallel, and a filler is filled between the reinforcing materials, and a cover material is arranged on the cover side of the reinforcing materials, and the cover material includes a bottom plate arranged on the cover side of the reinforcing materials, and a filler protrudes from the bottom plate toward the reinforcing materials, The plate surface is parallel to the axial direction of the reinforcement material. Located on the side of the reinforcement Plate-shaped and a protrusion. The protrusion may be disposed between the pair of stiffeners.

[0010] In the present invention, in a lap joint in which stress is transmitted between reinforcing materials via a filler, by providing a cover material on the cover side of the reinforcing material, it is possible to prevent adhesion cracking of the filler generated from the reinforcing material from progressing to the surface of the component, and by providing a protrusion disposed on the side of the reinforcing material as a cover material, it is possible to prevent adhesion cracking of the filler generated from the reinforcing material from progressing to the side. By controlling adhesion cracking in this way, it is possible to make the most of the adhesion strength of the material of the joint structure and realize a compact joint with a short joint length.

[0011] In addition, in the bottom plate, the axial direction of the reinforcing material This corresponds to the area of ​​the lap joint of the pair of reinforcing members. In position The bottom plate is divided into a plurality of portions in the axial direction of the reinforcing material. It is also desirable to provide joints. This allows cracks to occur in the filler due to openings in the joints, optimizes the adhesion stress distribution of the filler, and improves the stress transmission performance of the joint structure.

[0012] It is also preferable that a plurality of the reinforcing members are arranged on one of the bottom plates. By providing the cover material over multiple reinforcing materials, construction of the joint structure becomes easier.

[0013] It is also preferred that the covering material be formed from a fiber reinforced cementitious material. This allows the cover material to reliably prevent the adhesion cracking from progressing. Effect of the Invention

[0014] The present invention can provide a joint structure etc. that can realize a compact joint. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a joint structure 10. [Diagram 2] FIG. 2 is a cross-sectional view of the joint structure 10. [Diagram 3] A diagram showing main steel material 1. [Figure 4] Another example of cover material 3. [Diagram 5] 1A to 1C are diagrams for explaining the construction of the joint structure 10. [Figure 6] FIG. 2 shows the cover materials 3' and 3''. [Figure 7] FIG. 2 is a diagram showing a joint structure 10a. [Figure 8] 4 is a diagram for explaining the effect of a joint portion 311. FIG. [Figure 9] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0017] [First embodiment] Fig. 1 is a diagram showing a joint structure 10 according to a first embodiment of the present invention. The joint structure 10 is provided in a member made of concrete C. Fig. 1 shows a part of the member including the joint structure 10.

[0018] The joint structure 10 of this embodiment is a lap joint, in which a pair of main steel materials 1 are arranged overlapping each other so that their axial directions are parallel, and concrete C of a member is filled as a filler between the main steel materials 1. In the joint structure 10, when a pull-out force A in the axial direction acts on the main steel materials 1, stress is transmitted between the pair of main steel materials 1 via the concrete C.

[0019] Fig. 2 is a diagram showing a cross section of the joint structure 10. Fig. 2(a) is a cross section in the member thickness direction along the main steel material 1, and Fig. 2(b) is a planar cross section at the height of the main steel material 1.

[0020] The main steel material 1 is a reinforcing material that reinforces the concrete C of the member by bearing tensile forces, and the parts other than the lap joint are also embedded in the concrete C of the member. The surface of the main steel material 1 is formed with unevenness as shown in FIG. 3. In this embodiment, distribution steel material 4 is also provided in a direction perpendicular to the axial direction of the main steel material 1 in a plane. The main steel material 1 and distribution steel material 4 are made of shaped steel such as flat steel or H-shaped steel, but are not limited to these and other steel materials can also be used. Moreover, deformed bars (main bars or distribution bars) with uneven surfaces can be used as reinforcing materials within the member instead of the main steel material 1 and distribution steel material 4.

[0021] In the joint structure 10, a cover material 3 is placed on the cover side (component surface side) of the main steel material 1 to control bond splitting of the concrete C. The cover side of the main steel material 1 is the side in the direction perpendicular to the axial direction of the main steel material 1 (corresponding to the left-right direction in Fig. 2(a) and (b)) and the overlapping direction of the main steel material 1 (corresponding to the normal direction to the paper surface in Fig. 2(a) and the up-down direction in Fig. 2(b)).

[0022] The cover material 3 has high tensile strength and is formed using a fiber-reinforced cement-based material (fiber-reinforced cement-based composite material) such as fiber-reinforced mortar or fiber-reinforced concrete.

[0023] The bottom plate 31 is a flat rectangular plate material arranged along the axial direction of the main steel material 1 on the cover side of the main steel material 1. The bottom plate 31 is arranged with the plate surface facing the main steel material 1 side.

[0024] The protruding portion 32 is a plate material that protrudes from the plate surface of the bottom plate 31 towards the main steel material 1. The plate surface of the protruding portion 32 is arranged parallel to the axial direction of the main steel material 1. The height of the protruding portion 32 is determined so that the upper end of the protruding portion 32 is at or higher than the upper end of the main steel material 1.

[0025] The protrusions 32 are provided on both sides of the main steel material 1 on the plate surface of the bottom plate 31, and the protrusions 32 on the sides of the main steel material 1 are arranged between that main steel material 1 and the main steel material 1 adjacent thereto. A plurality of protrusions 32 are provided at intervals in the axial direction of the main steel material 1. The force distribution steel material 4 is passed between the protrusions 32 adjacent in the axial direction. Note that in this embodiment, an example is described in which the protrusions 32 are provided on both sides of each of the main steel materials 1 to be lap-jointed, but as shown in Figure 4, the protrusions 32 between a pair of main steel materials 1 to be lap-jointed may be omitted, and the pair of main steel materials 1 may be treated as one unit and the protrusions 32 may be provided only on both sides of the unit.

[0026] The covering material 3 is placed on a formwork F as shown in Fig. 5, for example, and used to arrange the main steel members 1 and the distribution steel members 4, and then concrete C for the members is poured on the formwork F. At this time, the concrete C is also filled around the main steel members 1 that constitute the lap joint, and the covering material 3 is embedded in the concrete C. In this way, the joint structure 10 is constructed.

[0027] In this embodiment, by providing the cover material 3 as described above, when a pull-out force A (tensile force) acts on the main steel material 1 due to bending of the member, etc., the bottom plate 31 prevents the adhesion cracking of the concrete C from progressing to the surface of the member, and the protrusion 32 prevents the adhesion cracking of the concrete C from progressing to the side of the main steel material 1, thereby preventing the adhesion cracking from penetrating into adjacent main steel materials 1, etc.

[0028] In this way, by controlling bond splitting with the cover material 3, it is possible to suppress the decrease in bond stress due to bond splitting and to make maximum use of the bond strength of the material of the joint structure 10. Therefore, it is possible to shorten the joint length of the main steel material 1 in the joint structure 10, and a compact joint structure 10 can be realized.

[0029] However, the present invention is not limited to the above embodiment. For example, the joint structure 10 is not limited to those that join main steel materials 1 together within a member, but can also be applied to cases where main steel materials 1 protruding from a pair of precast members are joined together, and the main steel materials 1 may be arranged between the precast members using the cover material 3 in the same manner as described above, and then filled with a filler. The filler is also not limited to the above-mentioned concrete C, and cement-based materials other than concrete C, such as mortar, may be used, and filler materials other than cement-based materials may also be used.

[0030] In addition, in the cover material 3 of this embodiment, the bottom plate 31 and the like are formed of fiber-reinforced mortar or the like and have high tensile strength, and can reliably prevent the progress of adhesion cracking, but the material of the bottom plate 31 is not particularly limited as long as it has a predetermined tensile strength, for example, a tensile strength higher than that of concrete C. For example, the bottom plate 31 may be made of mortar with a reinforcing member disposed therein, or a carbon fiber plate material may be used. Alternatively, a sheet material such as a steel mesh sheet may be used as the bottom plate 31, and the surface of the bottom plate 31 on the main steel material 1 side may be provided with irregularities to enhance the unity with the concrete C.

[0031] The protruding portion 32 may be formed from the same material as the bottom plate 31, or may be formed from a different material, such as steel or reinforcing bar. The shape of the protruding portion 32 is not limited to a plate shape, and for example, as shown in the cover material 3' in Fig. 6(a), a truss bar formed by combining reinforcing bars in a truss shape may be used as the protruding portion 32. Furthermore, in some cases, the protruding portion 32 may be omitted.

[0032] The bottom plate 31 is also not limited to being provided for each main steel material 1, but can also be provided so that it is continuous across multiple main steel materials 1, and these multiple main steel materials 1 can be arranged on a single bottom plate 31, as shown in the cover material 3'' in Figure 6(b). In this case too, by arranging a protrusion 32 between adjacent main steel materials 1, it is possible to prevent adhesion splitting from penetrating between the main steel materials 1. Furthermore, by providing a bottom plate 31 spanning multiple main steel materials 1, it is possible to simplify the positioning of the main steel materials 1, making it easier to construct the joint structure 10 and shortening the construction period. Figure 6(c) is an example in which, like Figure 4, the protrusion 32 between a pair of main steel materials 1 to be lap jointed is omitted, and protrusions 32 are provided only on both sides of the pair of main steel materials 1 as a unit, and in this case too, the bottom plate 31 can be provided so that it is continuous across multiple pairs of main steel materials 1.

[0033] In addition, with regard to the main steel material 1, it is possible to provide protrusions such as studs or perforated plates at the ends of the main steel material 1 located in the lap joint area to create unevenness and increase the adhesion of the concrete C, and it is also possible to improve the adhesion to the concrete C by providing an end plate at the tip of the main steel material 1.

[0034] Moreover, high-strength materials such as high-strength rebars (e.g., USD980) and fiber-reinforced polymers (e.g., CFRP) may be used as reinforcing materials instead of the main steel material 1. Even when using high-strength materials as reinforcing materials, there are many cases in which the potential of high-strength materials is not fully utilized due to bond splitting, and by using the cover material 3 of this embodiment, it becomes possible to achieve a rational design that utilizes the potential of high-strength materials by controlling bond splitting.

[0035] [Second embodiment] FIG. 7(a) is a diagram showing a joint structure 10a relating to a second embodiment of the present invention, and FIG. 7(b) is a diagram showing a cross section in the thickness direction of the member along the main steel material 1, similar to FIG. 2(a).

[0036] The joint structure 10a of the second embodiment differs from the first embodiment in that a joint portion 311 is provided in the bottom plate 31 of the cover material 3a at a predetermined position in the axial direction of the main steel material 1, and the bottom plate 31 is divided by the joint portion 311.

[0037] The joints 311 are made of a material having a lower tensile strength than the bottom plate 31 (parts excluding the joints 311), such as non-shrink mortar. The joints 311 are crack-inducing joints that open early due to bending of the members or the like and induce cracks in the concrete C at those positions, and are provided to optimize the bond stress of the concrete C within the range of the lap joint.

[0038] In other words, when a pull-out force A acts on the main steel material 1 due to bending of the component, etc., as shown in Figure 8(a), the slippage displacement between the main steel material 1 and the concrete C is usually concentrated at position P1, which is the base of the main steel material 1 in the lap joint range B, and cracks in the concrete C expand at position P1, while the slippage displacement is often smaller on the tip side of position P1.

[0039] As shown in Figure 8(b), the adhesion of concrete C increases with increasing slip displacement until the slip displacement reaches a certain value x, but when the slip displacement exceeds this value x due to the expansion of cracks, the adhesion tends to decrease.

[0040] As described above, when the pull-out force A is applied, cracks in the concrete C expand at position P1, which corresponds to the base of the main steel material 1, and the slippage exceeds the above-mentioned value x, making it difficult to maintain the adhesion. On the other hand, the slippage does not increase at a position closer to the tip of the main steel material 1 than position P1 (shown by symbol P2 in Figures 8(a) and (b)), which results in limiting the stress transmission performance of the lap joint.

[0041] Therefore, in this embodiment, the bottom plate 31 of the cover material 3a is provided with joints 311 for inducing cracks in the concrete C by early opening. As a result, cracks are generated in the concrete C at the positions of the joints 311, and the cracks in the concrete C caused by the pull-out force A are dispersed from position P1, which corresponds to the base portion of the main steel material 1, to other positions.

[0042] As a result, the slippage at position P1 corresponding to the base of the main steel material 1 becomes smaller as indicated by arrow a1 in Figure 8(b), approaching the aforementioned value x that maximizes the adhesive force. On the other hand, the slippage increases at the position of the joint 311 due to the concentration of cracks, and a certain amount of slippage occurs between the main steel material 1 and the concrete C even at a position next to the joint 311. Therefore, the slippage at position P2 on the tip side of the main steel material 1 can also be increased as indicated by arrow a2, and can be brought closer to the aforementioned value x that maximizes the adhesive force.

[0043] As a result, the bond stress of concrete C occurring in range B of the lap joint is higher on average than bond stress distribution c in the case where joint 311 is not provided, as shown in bond stress distribution b in Figure 8(c). Since the force that can be transmitted by a lap joint is the integral value of the bond stress distribution in range B of the lap joint, increasing this distribution on average leads to improved stress transmission performance and a reduction in the required joint length. Note that the bond stress value is smaller at the position of joint 311 in bond stress distribution b because cracks in concrete C are concentrated at that position, causing the slip displacement to exceed the aforementioned value x and become maximized.

[0044] Here, it is preferable to set the bottom plate 31 and the joint 311 so that the sum of the tensile forces borne by the bottom plate 31 and the main steel material 1 at the position P1 of the base of the main steel material 1 in the lap joint range B is equal to the sum of the tensile forces borne by the main steel material 1 at the position corresponding to the joint 311, and this allows the deviation between the concrete C and the main steel material 1 in the lap joint range B to be optimally averaged. Also, in FIG. 8(a), the joints 311 are provided at intervals in the axial direction of the main steel material 1, and the intervals are preferably equal to or less than the calculated value of the bending crack interval of the concrete C in the lap joint range B. In particular, it is preferable to use a material with high tensile strength for the bottom plate 31 in order to prevent the progress of bond splitting as described above. In this case, since bending cracks are unlikely to occur in the lap joint range B where the bottom plate 31 is installed, it is expected that bending cracks will concentrate at the boundary of the installation location of the bottom plate 31, i.e., the boundary of the lap joint. Even in such a case, by providing the joint portion 311 in the bottom plate 31, it becomes possible to control and disperse bending cracks in the area B of the lap joint.

[0045] In the second embodiment, the materials, shapes, etc. of the bottom plate 31 and the protruding portion 32 are not limited. For example, by using truss reinforcement as shown in FIG. 6(a) as the protruding portion 32, it is possible to integrate the bottom plate 31 divided by the joint portion 311, and the construction of the cover material 3a is simplified. Also, when the bottom plate 31 is provided across a plurality of main steel materials 1 as shown in FIG. 6(b), these joint portions 311 can be constructed collectively by aligning the positions of the joint portions 311 in the axial direction of the main steel materials 1 as shown in FIG. 9. This is also true when the bottom plate 31 is provided across a plurality of pairs of main steel materials 1 as shown in FIG. 6(c).

[0046] The joints 311 may also be made of the concrete C. In this case, the individual divided parts of the bottom plate 31 are arranged with gaps between them, and the concrete C is filled into the gaps when pouring the concrete C. In addition, it is also possible to use the high-strength material described above as a reinforcing material instead of the main steel material 1, and by arranging appropriate joints 311 in the bottom plate 31, the same effect as above can be obtained.

[0047] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to the above examples. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the technical ideas disclosed in this application, and it is understood that these also naturally belong to the technical scope of the present invention. [Explanation of symbols]

[0048] 1: Main steel material 3, 3', 3”, 3a, 3a': Cover material 4: Distribution steel material 10, 10a: Joint structure 31: Bottom plate 32:Protrusion 311: Joint section

Claims

1. A joint structure in which a pair of reinforcing materials having uneven surfaces are overlapped and arranged so that their axial directions are parallel, and a filler is filled between the reinforcing materials, A cover material is disposed on the covering side of the reinforcing material, The cover material is A bottom plate arranged on the cover side of the reinforcing material; a plate-shaped protruding portion protruding from the bottom plate toward the reinforcing material and disposed to the side of the reinforcing material with a plate surface parallel to an axial direction of the reinforcing material; A joint structure comprising:

2. The joint structure according to claim 1, characterized in that a joint portion is provided in the bottom plate at a position corresponding to the range of the lap joint of the pair of reinforcing members in the axial direction of the reinforcing member, dividing the bottom plate into multiple locations in the axial direction of the reinforcing member.

3. 3. The joint structure according to claim 1, wherein a plurality of the reinforcing members are disposed on one of the bottom plates.

4. A joint structure described in any one of claims 1 to 3, characterized in that the protrusion is arranged between the pair of reinforcing materials.

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