Joining structure and joining method

Abstract

To provide a joint structure and a joint method which can alleviate manufacturing accuracy required for a precast concrete plate and a steel material.SOLUTION: A joint structure 1 for joining a precast concrete plate 3 and a steel material unit 5 includes a steel material connection part 9 connected to a part of the precast concrete plate 3 and a part of the steel material unit 5. The steel material connection part 9 has a connection member 11 buried so as to partially project from an upper surface 3a of the precast concrete plate 3, a deviation preventing part 13 which is provided on the steel material unit 5 and is inserted into an insertion space 15 that is surrounded with the connection member 11 and is opened to the steel material unit 5 side, and a filling and solidification part 19 which is made to fill a gap between the connection member 11 and the deviation preventing part 13 in the insertion space 15, and is solidified.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a joining structure and joining method for joining a precast concrete slab and a steel material. [Background technology]

[0002] A known technology in this field is the precast composite member described in Patent Document 1 below. When manufacturing this precast composite member, a precast concrete member manufactured in advance at a factory is attached to a steel panel manufactured in advance at a factory, and a fluid hardener is poured between the steel panel and the precast concrete member, thereby integrating the steel panel and the precast concrete member. When assembling the precast concrete member and the steel panel, the deformed reinforcing bars of the precast concrete member are hooked into L-shaped notches provided in the ribs of the steel panel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-163813 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above assembly structure, there is a possibility that assembly will not be possible if there is a large manufacturing error in the L-shaped notch or deformed rebar. Therefore, high manufacturing accuracy is required for the precast concrete members and steel panels at each factory, which can hinder cost reduction, etc. The object of the present invention is to provide a joining structure and joining method that alleviates the manufacturing accuracy required for the precast concrete slabs and steel materials. [Means for solving the problem]

[0005] The connection structure of the present invention is a connection structure for joining a precast concrete slab and a steel material, and is provided with a steel connection portion that connects a portion of the precast concrete slab to a portion of the steel material.The steel connection portion has: a connection member embedded in the precast concrete slab so that a portion of it protrudes from the surface of the precast concrete slab toward the steel material; a slip prevention portion provided on the steel material so that it protrudes toward the precast concrete slab, and inserted into an insertion space surrounded by the connection member and opening toward the steel material; and a filled and solidified portion that fills and solidifies the gap between the connection member and the slip prevention portion within the insertion space.

[0006] The connection member may be a tubular member protruding from the surface of the precast concrete slab in the axial direction, and the insertion space may be a hollow portion of the tubular member. The steel connection portion may further include a reinforcing bar embedded in the precast concrete slab and at least a portion of which is inserted into the insertion space. The connection member may also be fixed to the precast concrete slab via the reinforcing bar. The surface of the connection member of the steel connection portion may be provided with irregularities. The steel connection portion may further include a loop reinforcing bar extending in a loop shape on the outer peripheral surface of the connection member so as to surround the connection member in the circumferential direction. In the connection structure of the present invention, there may be multiple steel connection portions for one steel member. In the steel connection portion, the amount of protrusion of the connection member from the surface of the precast concrete slab may be smaller than the insertion length of the shear stopper inserted into the insertion space.

[0007] Furthermore, the joining method of the present invention is a method for joining a precast concrete slab and a steel material, which constructs a joint structure including the above-mentioned reinforcing bar at least partially inserted into the insertion space, and includes a precast concrete slab production step of producing a precast concrete slab in which a connecting member and a reinforcing bar are installed, and in the precast concrete slab production step, a concrete portion of the precast concrete slab is poured so as to embed the reinforcing bar and the connecting member, with the connecting member fixed to the reinforcing bar. According to this method, since the connecting member is fixed to the reinforcing bar when the concrete portion is poured to produce the precast concrete slab, the effort of providing a separate spacer or the like to properly position the connecting member within the concrete formwork is eliminated. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a joining structure and joining method that relaxes the manufacturing precision required for precast concrete slabs and steel materials. [Brief explanation of the drawings]

[0009] [Figure 1] (a) is an exploded oblique view showing the state before joining using the joining structure of this embodiment, (b) is an oblique view showing a composite half-precast member, and (c) is a cross-sectional view showing one of the steel connection parts. [Figure 2] 10(a) to 10(c) are diagrams showing steel material joints according to modified examples. [Figure 3] (b), (d), and (f) are cross-sectional views of the vicinity of the steel material connection part according to each modification, and (a), (c), and (e) are the respective AA cross-sectional views. [Figure 4] 10(b) and 10(d) are cross-sectional views of the vicinity of the steel material connection portion according to each modification, and 10(a) and 10(c) are cross-sectional views taken along the line AA of each. [Figure 5] (a) and (b) are cross-sectional views of the vicinity of the steel connection part in each modified example, and (c) is an oblique view showing the state in which the connection member in the modified example is installed on a precast concrete slab. [Figure 6]10(a) to 10(d) are diagrams showing steel material connections according to modified examples. [Figure 7] 1 is a cross-sectional view showing an example in which the joint structure of this embodiment is applied to a box culvert 100. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of a joining structure and joining method according to the present invention will be described in detail with reference to the drawings. The joining structure 1 of this embodiment shown in FIG. 1 joins a precast concrete slab 3 and a steel unit 5. The precast concrete slab 3 is a plate-shaped member made of reinforced concrete that is manufactured in a factory. Reinforcing bars 21 (see FIG. 3(a) and the like) embedded in the precast concrete slab 3 are omitted from the illustrations unless necessary for the explanation. The steel unit 5 is shown in a simplified schematic form in the drawings, but is actually a unit constructed by assembling, for example, multiple steel members, and is manufactured in a factory.

[0011] Figure 1(a) is an exploded perspective view showing a precast concrete slab 3 and a steel unit 5 before joining, and Figure 1(b) is a perspective view showing a composite half-precast member 7 formed by joining the precast concrete slab 3 and the steel unit 5. Such composite half-precast member 7 is used in the construction of a framework and contributes to improving the productivity of framework construction by eliminating the need for shoring on the underside and sides of the formwork. Hereinafter, as shown in the figure, mutually orthogonal X, Y, and Z directions are defined and X, Y, and Z are sometimes used to explain the positional relationship of each part. Furthermore, when terms such as "upper / lower" and "top / bottom" are used in the explanation, they correspond to the top and bottom of the precast concrete slab 3 and the steel unit 5 as shown in Figure 1(a). The precast concrete slab 3 is a flat plate that exists along the XY plane, and the steel unit 5 and the precast concrete slab 3 are joined in the Z direction.

[0012] As shown in Figure 1(b), the joint structure 1 has four steel connection parts 9 arranged in the Y direction. At each of these four steel connection parts 9, a portion of the precast concrete slab 3 is connected to a portion of the steel unit 5, thereby joining the precast concrete slab 3 to the steel unit 5. Figure 1(c) is a cross-sectional view showing one of the steel connection parts 9.

[0013] As shown in FIG. 1(a), connection members 11 are installed on the upper surface 3a of the precast concrete slab 3 at positions corresponding to each steel connection portion 9. The connection members 11 are tubular members, and for example, standard-standard steel pipes may be used as the connection members 11. In the example of FIG. 1, the connection members 11 are cylindrical members, and standard-standard circular steel pipes may be used as the connection members 11. By using standard-standard members in this manner, special processing of the members may be omitted, thereby reducing manufacturing costs. The connection members 11 are embedded in the precast concrete slab 3 at their lower ends with their cylindrical axes facing the Z direction, and their upper ends protrude upward (in the Z direction) from the upper surface 3a of the precast concrete slab 3 toward the steel unit 5. When manufacturing the precast concrete slab 3, for example, the connection members 11 are appropriately positioned on the reinforcing bars 21 (see FIG. 3(a) and other figures) embedded in the precast concrete slab 3 via appropriate spacers or the like, and then concrete is poured.

[0014] The hollow portion of the connecting member 11 is a space surrounded by the connecting member 11 and open to the steel unit 5 side, and is an insertion space 15 into which a slip prevention portion 13 of the steel unit 5, which will be described later, is inserted in the axial direction of the cylinder. The inner diameter of the connecting member 11 is, for example, approximately 100 mm, and the amount by which the connecting member 11 protrudes from the top surface 3a is, for example, approximately 50 to 80 mm. The top surface 3a of the precast concrete slab 3 also appears within the hollow portion of the connecting member 11. The top surface 3a within the hollow portion of the connecting member 11 is located at the same height as the top surface 3a on the outer circumferential side of the connecting member 11.

[0015] Additionally, at positions corresponding to the steel connection portions 9, the steel units 5 are provided with shear stoppers 13 that protrude downward (in the Z direction) toward the precast concrete slabs 3. The shear stoppers 13 are, for example, made of rod-shaped steel welded to the surface (bottom surface 5a) of the steel units 5 facing the precast concrete slabs 3 and extending in the Z direction. In the example shown in FIG. 1 , the shear stoppers 13 are headed studs that have a rounded rod-shaped main body and a head with a slightly larger diameter provided at the tip of the main body. The outer diameter of the shear stoppers 13 is smaller than the inner diameter of the connecting members 11, for example, approximately 16 to 22 mm. Furthermore, the shear stoppers 13 protrude from the bottom surface 5a of the steel units 5 by, for example, approximately 50 to 80 mm, which is slightly smaller than the protrusion of the connecting members 11 from the top surface 3a of the precast concrete slabs 3.

[0016] As shown in Figures 1(b) and 1(c), in the steel connection portion 9, the shear stopper 13 of the steel unit 5 is inserted in the Z direction into the hollow portion (insertion space 15) of the connection member 11. Here, the lower surface 5a of the steel unit 5 may abut against the upper end surface of the connection member 11. In the steel connection portion 9, due to the relationship between the inner diameter of the connection member 11 and the outer diameter of the shear stopper 13, a gap is created in the radial direction (XY direction) between the connection member 11 and the shear stopper 13. Furthermore, due to the above-mentioned relationship in the protrusion amounts between the connection member 11 and the shear stopper 13, the protrusion amount of the connection member 11 from the upper surface 3a of the precast concrete slab 3 is greater than the insertion length of the shear stopper 13 inserted into the insertion space 15. Therefore, the tip of the shear stopper 13 does not reach the upper surface 3a of the precast concrete slab 3, which exists as the bottom surface of the insertion space 15.

[0017] After the shear stopper 13 is inserted into the insertion space 15 as described above, a fluid solidifying material is injected into the gap between the connecting member 11 and the shear stopper 13 within the insertion space 15. The solidifying material may be injected to a height that reaches the upper edge of the connecting member 11. In this embodiment, non-shrinkage mortar is used as the solidifying material. As the solidifying material solidifies, a filled and solidified portion 19 is formed, which fills and solidifies the gap between the connecting member 11 and the shear stopper 13 within the insertion space 15. The shear stopper 13 is firmly fixed to the connecting member 11 via this filled and solidified portion 19. In this way, the radial gap between the connecting member 11 and the shear stopper 13 is filled with the filled and solidified portion 19, thereby ensuring the shear resistance of the steel connection portion 9. Furthermore, the use of a headed stud as the shear stopper 13 ensures the pull-out resistance of the shear stopper 13 from the insertion space 15, thereby ensuring the pull-out resistance of the steel connection portion 9. Therefore, at the steel joint 9, a portion of the precast concrete slab 3 and a portion of the steel unit 5 are firmly connected.

[0018] Then, a joint structure 1 is completed in which one steel unit 5 is joined to the precast concrete slab 3 by four steel connection parts 9. A composite half-precast member 7 is completed by joining multiple or a single steel unit 5 to the precast concrete slab 3 using the above-mentioned joint structure 1. In the example of Figure 1, there are four steel connection parts 9 for one steel unit 5, but the number of steel connection parts 9 for one steel unit 5 may be changed as appropriate. There may also be only one steel connection part 9 for one steel unit 5.

[0019] The effects of the above-described joint structure 1 will now be described. In the steel connection portion 9 of the joint structure 1, the outer diameter of the shear stopper 13 is smaller than the inner diameter of the connection member 11, so there is a radial gap between the shear stopper 13 and the inner wall surface of the connection member 11. Therefore, even if there is a positional error between the shear stopper 13 and the connection member 11 due to a manufacturing error between the precast concrete slabs 3 and the steel unit 5, the radial gap can absorb the positional error. In other words, it is possible to avoid an event where the shear stopper 13 cannot be inserted into the insertion space 15 due to the positional error.

[0020] Therefore, a certain degree of manufacturing error is allowed for the precast concrete slabs 3 and the steel units 5, i.e., the required manufacturing precision is relaxed. For example, compared to a structure in which the precast concrete slabs 3 and the steel units 5 are joined via splice plates or directly with bolts, the manufacturing precision of the precast concrete slabs 3 and the steel units 5 can be relaxed. This reduces the burden of managing the manufacturing precision of the precast concrete slabs 3 and the steel units 5, and as a result, the manufacturing cost of the composite half precast member 7 can be reduced. In particular, when there are multiple steel connection portions 9 for one steel unit 5, the required precision for the positional relationships between the multiple connection members 11 and the positional relationships between the multiple shear stoppers 13 is also relaxed, further relaxing the manufacturing precision required for the precast concrete slabs 3 and the steel units 5.

[0021] Furthermore, compared to a structure that uses bolt fastening to join the precast concrete slab 3 and the steel unit 5, the number of bolt holes formed in the main steel material is reduced, and cross-sectional loss is reduced, allowing for a streamlined design with no waste.

[0022] Furthermore, compared to a structure in which the precast concrete slabs 3 and the steel units 5 are joined by welding, the joint structure 1 of this embodiment makes it easier to stably ensure the quality of the joint regardless of the skill of the worker. Furthermore, while joining by welding requires, for example, relatively strict rain protection of the work area, the joint structure 1 makes it possible to perform the joining work with simple rain protection, meaning that the joining work can be performed relatively easily regardless of the work environment.

[0023] Furthermore, in the steel connection portion 9 of the joint structure 1, the insertion space 15 for inserting the shear stopper 13 is formed by being surrounded by a member embedded in the precast concrete slab 3. Alternatively, another method could be to form a box cutout portion in the precast concrete slab 3 to create the insertion space 15. However, forming the box cutout portion in the precast concrete slab 3 requires the installation and removal of a floating formwork, which reduces manufacturing efficiency. Furthermore, there is a risk of deterioration in the quality of the precast concrete slab 3, such as imperfect filling of concrete below the floating formwork or chipping of corners when the floating formwork is removed. In contrast, in the joint structure 1, the insertion space 15 is formed by being surrounded by a member embedded in the precast concrete slab 3, which improves the manufacturing efficiency and quality of the precast concrete slab 3 compared to the method of forming a box cutout portion in the precast concrete slab 3.

[0024] The present invention can be implemented in various forms, including the above-described embodiment, with various modifications and improvements based on the knowledge of those skilled in the art. It is also possible to configure modified versions by utilizing the technical matters described in the above-described embodiment. The configurations of the embodiment and modified versions may be used in appropriate combination.

[0025] Modified examples of the joint structure 1 will be described below. In the above-described embodiment, the connection member 11 is cylindrical. However, instead of this, as shown in FIG. 2( a), for example, a rectangular tubular connection member 11B (e.g., a square steel pipe) may be used. A steel pipe of a general standard may be used for the connection member 11B. Also, as shown in FIG. 2( b), a tapered connection member 11C (e.g., a tapered steel pipe) that widens downward may be used. The connection member 11C may have a circular cross section or a rectangular cross section. A steel pipe of a general standard may be used for the connection member 11C. In a structure using the connection member 11C, the tapered shape improves the pull-out resistance of the connection member 11C from the precast concrete slabs 3, which in turn improves the pull-out resistance of the steel connection portion 9.

[0026] Furthermore, instead of the connecting member 11, a structure may be used in which the insertion space 15D is surrounded by a connecting member 11D made up of a combination of multiple steel members, as shown in FIG. 2(c). In the example of FIG. 2(c), the connecting member 11D is made up of four flat steel members arranged in a rectangular shape in a plan view, but the number and shape of the members constituting the connecting member 11D are not limited as long as the shape surrounds the insertion space 15D with multiple members. For example, the members constituting the connecting member 11D are not limited to flat steel members, and the connecting member 11D may also include angle iron or channel iron.

[0027] Furthermore, elements such as those shown in FIGS. 3 to 5 may be added to improve the shear resistance and pull-out resistance of the steel connection portion 9. FIGS. 3(b), 3(d), and 3(f) are cross-sectional views of the vicinity of the steel connection portion 9 according to each modification, with their respective AA cross-sectional views shown in FIGS. 3(a), 3(c), and 3(e). Similarly, FIGS. 4(b) and 4(d) are cross-sectional views of the vicinity of the steel connection portion 9 according to each modification, with their respective AA cross-sectional views shown in FIGS. 4(a) and 4(c). FIGS. 5(a) and 5(b) are cross-sectional views of the vicinity of the steel connection portion 9 according to each modification, with FIG. 5(c) being a perspective view showing a connection member 11E according to a modification installed on a precast concrete slab 3. The filled and solidified portion 19 (see FIG. 1(c)) filled in the insertion space 15 is omitted from FIGS. 3 to 5.

[0028] The steel connection portion 9 shown in FIGS. 3(a) to 3(d) includes a reinforcing steel bar embedded in the precast concrete slab 3 and at least a portion of which is inserted into the insertion space 15. Specifically, the steel connection portion 9 shown in FIGS. 3(a) and 3(b) includes a reinforcing steel bar 23A. Both ends of the reinforcing steel bar 23A extend to the outside of the connection member 11 in a plan view and are fixed to the reinforcing steel bar 21 in the main body of the precast concrete slab 3, for example, by welding or wire. The central portion of the reinforcing steel bar 23A is curved in an inverted U-shape and inserted into the insertion space 15 through the lower end opening of the connection member 11. The upper end of the central portion of the reinforcing steel bar 23A protrudes above the upper surface 3a and passes beside the shear stopper 13. The reinforcing steel bar 23A is embedded in the filled and solidified portion 19 (see FIG. 1(c)) together with the shear stopper 13. Here, two reinforcing steel bars 23A as described above are provided parallel to each other.

[0029] The manufacturing procedure (precast concrete slab manufacturing process) for the precast concrete slab 3 including the reinforcing bars 23A can be, for example, as follows: Before concrete is poured, the reinforcing bars 23A are installed on the reinforcing bars 21, and the connecting member 11 is installed and fixed on the reinforcing bars 23A so that the connecting member 11 covers the upper end of the inverted U-shaped reinforcing bars 23A. Alternatively, the connecting member 11 and the reinforcing bars 23A may be integrated in advance and then installed and fixed on the precast concrete slab 3 before concrete is poured. As an example of how the connecting member 11 is fixed to the reinforcing bars 23A, for example, the connecting member 11 may be welded to the reinforcing bars 23A, or the upper ends of the two reinforcing bars 23A may be fitted into the hollow portions of the connecting member 11 to such an extent that they do not easily fall out or move. Then, the concrete portion of the main body of the precast concrete slab 3 is poured so as to embed the reinforcing bars 21, the lower parts of the reinforcing bars 23A, and the lower parts of the connecting member 11. According to this procedure, the connecting member 11 is installed and fixed using the reinforcing steel bars 23A as a base, eliminating the need for additional spacers or the like to properly position the connecting member 11 within the concrete formwork. In the steel connection part 9 that is finally completed through this manufacturing procedure for the precast concrete slab 3, the connecting member 11 is fixed to the reinforcing steel bars 23A inside the poured concrete or inside the filled and solidified part 19. Furthermore, the connecting member 11 is fixed to the precast concrete slab 3 via the concrete portion of the precast concrete slab 3, and also via the reinforcing steel bars 23A.

[0030] 3(c) and (d) is a spiral reinforcement that extends helically coaxially with the connecting member 11. The lower end of the reinforcing bar 23B is fixed to the reinforcing bar 21 in the main body of the precast concrete slab 3, for example, by welding or wire. The upper end of the reinforcing bar 23B is inserted into the insertion space 15 through the lower end opening of the connecting member 11 and protrudes above the upper surface 3a. The upper end of the reinforcing bar 23B is arranged so as to wrap around the shear stopper 13, and is embedded together with the shear stopper 13 in the filled and solidified portion 19 (see FIG. 1(c)).

[0031] 3(e), (f) and 4(a), (b) show steel connection parts 9 in which reinforcing bars are welded to the inner wall surface of the connection member 11 to form irregularities. In the steel connection part 9 of FIGS. 3(e) and (f), arc-shaped reinforcing bars 27A extending in the circumferential direction of the connection member 11 along the XY plane are welded to the inner wall surface of the connection member 11. Here, multiple (for example, four) reinforcing bars 27A are arranged in parallel at equal intervals in the cylindrical axial direction of the connection member 11, two of which are embedded in the precast concrete slab 3, and the remaining two are located in the insertion space 15 and embedded in the filling and solidification part 19.

[0032] In the steel connection portion 9 in FIGS. 4(a) and 4(b), a straight reinforcing bar 27B extending in the axial direction of the connection member 11 is welded to the inner wall surface of the connection member 11. Here, a plurality of (e.g., six) reinforcing bars 27B are arranged in the circumferential direction of the connection member 11. The upper part of the reinforcing bar 27B is located in the insertion space 15, and the lower part of the reinforcing bar 27B is embedded in the precast concrete slab 3. As shown in the figures, the lower end of the reinforcing bar 27B may be bent outward below the lower end opening of the connection member 11 and extend radially. Furthermore, the lower end of this reinforcing bar 27B may be fixed to the reinforcing bar 21 using, for example, welding or wire.

[0033] 4(c) and (d) includes a loop reinforcing bar 29 that extends in a loop shape on the outer peripheral surface of the connecting member 11 so as to surround the connecting member 11 in the circumferential direction. The loop reinforcing bar 29 has a circular ring shape that extends in the circumferential direction of the connecting member 11 along the XY plane and is welded to the outer wall surface of the connecting member 11. Here, a plurality of (for example, four) loop reinforcing bars 29 are arranged in parallel at equal intervals in the cylindrical axial direction of the connecting member 11, two of which are embedded in the precast concrete slab 3, and the remaining two are located between the upper surface 3a of the precast concrete slab 3 and the lower surface 5a of the steel unit.

[0034] The effect of the loop reinforcing bars 29 is as follows: When the shear stopper 13 attempts to slip out of the connecting member 11 in the axial direction of the tube, it is thought that a force is generated that tries to push the connecting member 11 radially outward via the filled and solidified portion 19. In contrast, in the steel connection part 9 of Figures 4(c) and (d), the loop reinforcing bars 29 are welded to the outer peripheral surface, improving the rigidity of the connecting member 11 and increasing resistance to the above-mentioned radially expanding force. As a result, in this steel connection part 9, the pull-out resistance of the shear stopper 13 from the connecting member 11 is improved.

[0035] 5(a) and 5(b) show a steel connection part 9 that provides a stopper on the inner wall surface of the connection member 11. In the steel connection part 9 of FIG. 5(a), a plurality of studs 31 are welded to the inner wall surface of the connection member 11. Some of the studs 31 are embedded in the precast concrete slab 3, and the remaining part is located in the insertion space 15 and embedded in the filled and solidified part 19. In the steel connection portion 9 shown in FIG. 5( b), multiple perforated steel plates 33 are welded to the inner wall surface of the connection member 11. The perforated steel plates 33 are elongated plates that rise radially inward from the inner wall surface of the connection member 11 and extend vertically. Each perforated steel plate 33 has through holes 33a that penetrate the plate thickness direction and are spaced equally apart vertically. In the example shown, one perforated steel plate 33 has three through holes 33a, but the number of through holes 33a may be changed as appropriate. The lower part of each perforated steel plate 33 is embedded in the precast concrete slabs 3, and the upper part of each perforated steel plate 33 is located in the insertion space 15 and embedded in the filled and solidified portion 19. The presence of these perforated steel plates 33 improves the pull-out resistance of the connection member 11 from the precast concrete slabs 3, thereby improving the pull-out resistance of the steel connection portion 9.

[0036] Furthermore, the connection member 11 of the steel connection portion 9 in the form shown in Figure 5(c) is perforated in the portion that will be embedded in the precast concrete slab 3. That is, the portion of the connection member 11 that will be embedded in the precast concrete slab 3 has multiple circular through holes 35 that penetrate the cylindrical wall. The number and arrangement of the through holes 35 are designed appropriately. The presence of these through holes 35 improves the pull-out resistance of the connection member 11 from the precast concrete slab 3, and ultimately improves the pull-out resistance of the steel connection portion 9.

[0037] Furthermore, as shown in FIG. 6(a), instead of the shear stopper 13 (FIG. 1(a)) composed of a headed stud, a shear stopper 13B composed of a perforated steel plate dowel may be provided on the steel unit 5. The shear stopper 13B is a long plate-like member that rises downward from the underside 5a of the steel unit 5 toward the precast concrete slab 3. The shear stopper 13B has through holes 14a that penetrate the plate thickness direction and are formed at equal intervals in the horizontal direction. In the example shown in the figure, three through holes 14a are formed in the shear stopper 13B, but the number of through holes 14a may be changed as appropriate. The presence of the through holes 14a improves the pull-out resistance of the shear stopper 13B from the insertion space 15, thereby improving the pull-out resistance of the steel connection part 9.

[0038] As shown in Figures 6(b) and 6(c), instead of the shear stopper 13 (Figure 1(a)) composed of a headed stud, a shear stopper 13C made of flat steel and having an anchor may be provided on the steel unit 5. Figure 6(b) is a perspective view of the steel connection part 9 including the shear stopper 13C, and Figure 6(c) is its cross-sectional view. The shear stopper 13C has a long plate-shaped main body part 14b that rises downward from the underside 5a of the steel unit 5 toward the precast concrete slab 3, and an anchor part 14c formed so as to protrude from the lower end of the main body part 14b in the X and / or Y directions. The presence of this anchor part 14c improves the pull-out resistance of the shear stopper 13C from the insertion space 15, thereby improving the pull-out resistance of the steel connection part 9.

[0039] 6(d), the bottom surface 15a of the insertion space 15 may be located lower than the upper surface 3a of the precast concrete slab 3. The lower end of the shear stopper 13 may be inserted into the insertion space 15 to a position lower than the upper surface 3a. In a steel connection part 9 with this structure, the amount of protrusion of the connection member 11 from the upper surface 3a of the precast concrete slab 3 is smaller than the insertion length of the shear stopper 13 inserted into the insertion space 15. With this structure, the shear stopper 13 is inserted deep into the precast concrete slab 3, improving the specifications of the shear stopper 13 and increasing the shear resistance and pull-out resistance of the steel connection part 9.

[0040] In order to form the bottom surface 15a as described above, when manufacturing the precast concrete slab 3, the concrete of the precast concrete slab 3 is poured with a temporary filler filled in the hollow portion of the connecting member 11 or with the lower end opening of the connecting member 11 blocked by, for example, a membrane-like lid member, and the temporary filler or lid member is then removed afterwards.

[0041] Although not shown, in the steel connection portion 9, a plurality of anti-slip portions 13, 13B, 13C may be inserted into one insertion space 15. Furthermore, by providing protrusions or the like on the inner wall surface or outer wall surface of the connection members 11, 11B, 11C, 11D, 11E to provide irregularities, the connection members 11 to 11E may be made to have a higher degree of integration with the concrete of the precast concrete slab 3 and the filled and solidified portion 19.

[0042] Furthermore, the connecting members 11-11E are not limited to steel members but may be made of ultra-high-strength fiber-reinforced concrete or the like. In this case, it is relatively easy to create irregularities on the inner and outer wall surfaces of the connecting members 11-11E. Furthermore, in this case, it is relatively easy to manufacture connecting members 11-11E of any size or shape other than standard sizes. Furthermore, the solidifying material used for the filling and solidifying portion 19 is not limited to non-shrinkage mortar. Various materials can be used as long as they can be fluidly injected into the insertion space 15 and subsequently solidify. For example, the solidifying material may be an expansive material that expands upon solidification. In this case, the expansion of the solidifying material tightens the shear stopper 13 within the insertion space 15, thereby improving the restraining effect of the shear stopper 13. Furthermore, the connection structure 1 is not limited to joining a steel unit 5 consisting of multiple steel members to a precast concrete slab 3, but can also be applied to a structure for joining a single steel member to a precast concrete slab 3.

[0043] Next, an example in which the above-mentioned joint structure 1 is applied to a box culvert 100 will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view showing the vicinity of the top slab 102 of the box culvert 100. When constructing the top slab 102, a composite half-precast member 107 is used as a formwork structure for pouring concrete for the top slab 102. The composite half-precast member 107 includes a precast concrete slab 103 and a steel unit 105 joined by the above-mentioned joint structure 1.

[0044] The precast concrete slab 103 is a precast member in the form of a horizontal plate that functions as an embedded formwork for the top slab 102. The steel unit 105 is composed of multiple steel materials, such as main steel materials 111, 112 that extend horizontally across the entire top slab 102, multiple vertical steel materials 113 that connect the main steel materials 111, 112 vertically, diagonal materials 115 that connect the main steel materials 111, 112 diagonally, and panel materials 117 that are placed at both ends of the top slab 102. The steel unit 105 has high rigidity when assembled and constructed using such multiple steel materials. The precast concrete slab 103 and the steel unit 105 are each prefabricated in separate factories.

[0045] A composite half-precast member 107 is constructed by joining the above-described precast concrete slabs 103 and steel units 105 in the vertical direction using a joint structure 1 having the aforementioned steel connection portions 9. Specifically, a connection member 11 (see FIG. 1(a)), for example, is provided on the upper surface 103a of the precast concrete slab 103, and a shear stopper 13 (see FIG. 1(a)), for example, is provided on the lower surface 105a of the steel unit 105 (the lower surface of the main steel member 112), thereby constructing the steel connection portion 9. Note that any of the steel connection portions 9 shown in FIGS. 1 to 6 may be employed, or the components of the steel connection portions 9 shown in FIGS. 1 to 6 may be combined as appropriate. The joint structure 1 in the illustrated example has six steel connection portions 9, but the number of steel connection portions 9 may be changed as appropriate.

[0046] In constructing the top slab 102, the composite half precast member 107 is erected between both side walls 119, 119 of the box culvert 100, the precast concrete slab 103 is used as an embedded formwork, other necessary formwork is installed, and concrete 121 is poured. The steel units 105 are embedded in the top slab 102, and the top slab 102 is constructed with the precast concrete slab 103 exposed in the hollow part of the box culvert 100.

[0047] As mentioned above, because the steel units 105 have high rigidity, it is possible to omit shoring to support the precast concrete slab 103 from below when the composite half precast members 107 are erected between the side walls 119, 119 and concrete is poured for the top slab 102. In addition, because the steel units 105 function as reinforcing materials for the top slab 102, it is possible to reduce the amount of reinforcing bars in the top slab 102, and therefore the work of arranging the reinforcing bars can be reduced. [Explanation of symbols]

[0048] 1...joint structure, 3,103...precast concrete slab, 3a,103a...top surface, 5,105...steel unit (steel), 9...steel connection part, 11,11B,11C,11D,11E...connection member, 13...slip prevention part, 15,15D...insertion space, 19...filled solidification part, 23A,23B...reinforcing steel bar, 29...loop steel bar.

Claims

1. In a composite half-precast member for constructing a skeleton, a precast concrete slab that serves as an embedded formwork when pouring concrete for the skeleton and a steel material that is embedded in the skeleton and serves as a reinforcing material are joined together in a joint structure, a steel connection portion that connects a portion of the precast concrete slab to a portion of the steel material; The steel connection portion is a connecting member embedded in the precast concrete slab so that a portion of the connecting member protrudes from the surface of the precast concrete slab toward the steel material; a stopper portion provided on the steel material so as to protrude toward the precast concrete slab, surrounded by the connecting member, and inserted into an insertion space that opens toward the steel material; a filled and solidified portion that is filled and solidified in a gap between the connecting member and the displacement prevention portion within the insertion space, A joint structure in which there are multiple steel material connection portions for one steel material.

2. the connecting member is a cylindrical member protruding from the surface of the precast concrete slab in a cylindrical axis direction, and the insertion space is a hollow portion of the cylindrical member; The steel connection portion further includes a reinforcing bar embedded in the precast concrete slab and at least a portion of which is inserted into the insertion space, The joint structure according to claim 1 , wherein the connecting member is fixed to the precast concrete slab via the reinforcing bar.

3. The joining structure according to claim 2 , wherein the surface of the connecting member of the steel material connecting portion is provided with irregularities.

4. The joining structure according to claim 2 or 3, wherein the steel connection portion further comprises a loop reinforcing bar extending in a loop shape on the outer circumferential surface of the connection member so as to surround the connection member in the circumferential direction.

5. 5. The joining structure according to claim 1, wherein the stopper is a headed stud.

6. A joint structure described in any one of claims 1 to 5, wherein at the steel connection portion, the amount of protrusion of the connection member from the surface of the precast concrete slab is smaller than the insertion length of the anti-slip portion inserted into the insertion space.

7. A method for joining a precast concrete slab and a steel material to construct the joint structure according to any one of claims 2 to 4, a precast concrete slab manufacturing process for manufacturing the precast concrete slab on which the connection members and the reinforcing bars are installed, In the precast concrete slab manufacturing process, A joining method in which, with the connecting member fixed to the reinforcing bar, the concrete portion of the precast concrete slab is poured so as to embed the reinforcing bar and the connecting member.

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