Joint structure and joint construction method

Abstract

To provide a joint structure and a joint construction method that enables simple construction of joints of shape steel to be buried in concrete.SOLUTION: A joint structure 1 is a joint structure connecting lower main steel members 11,11 that are buried in concrete 17, and has a joint reinforcement section 21 that is placed near a connection portion 11P of the lower main steel members 11,11 so as to extend longitudinally over both lower main steel members 11,11 that are connected longitudinally to each other and is buried together with the lower main steel members 11,11 in the concrete 17.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, for example, a composite member has been known that includes an embedded formwork made of concrete and a main steel member made of shaped steel fixed to the embedded formwork (see, for example, Patent Document 1 below). In this composite member, a steel-reinforced concrete structure is constructed by pouring concrete into the embedded formwork so as to embed the main steel member. This type of composite member itself has high rigidity, so it is possible to omit shoring on the underside and sides of the formwork, which is effective in improving productivity in building the skeleton. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-183799 Summary of the Invention [Problem to be solved by the invention]

[0004] When this type of composite member is installed in sections, joints of the main steel members are generated between the members, and friction joints and welded joints are considered as joints of the main steel members. However, these joint structures require a large amount of work on-site and require precise installation of the main steel members, which can impair workability. In view of these problems, the present invention aims to provide a joint structure and a joint construction method that enable easy construction of joints between shaped steel members embedded in concrete. [Means for solving the problem]

[0005] The joint structure of the present invention is a joint structure that connects structural steel beams embedded in concrete, and is equipped with a joint reinforcing bar portion that is arranged near the connection between the structural steel beams so as to extend longitudinally across both ends of the structural steel beams that are connected to each other longitudinally, and is embedded in the concrete together with the structural steel beams.

[0006] In the joint structure of the present invention, a plurality of joint reinforcing bar parts may be arranged in parallel with one connecting part, and the joint reinforcing bar parts may be connected to each other via other reinforcing bars. Anchoring parts may be provided at both ends of the joint reinforcing bar parts to improve anchoring performance to concrete. The joint reinforcing bar parts may form part of the hoop reinforcing bar.

[0007] The above-mentioned structural steel may be the main steel material fixed to the precast concrete slab along the surface of the precast concrete slab in a composite half-precast member having a precast concrete slab, and concrete may be poured using the precast concrete slab as an embedded formwork.

[0008] In the joint structure of the present invention, multiple connection portions between the main steel members are present along the surface of the precast concrete slab so as to be aligned in a direction perpendicular to the longitudinal direction, and multiple joint reinforcing bar portions respectively arranged at multiple connection portions may be connected to each other at a position farther from the precast concrete slab than the main steel members.

[0009] The composite half-precast member may further have a second main steel member arranged parallel to the main steel member at a position farther from the precast concrete slab than the main steel member, and may further include a second joint reinforcing bar portion arranged near the connection between the second main steel members so as to extend longitudinally across both ends of the second main steel members that are connected to each other longitudinally, and buried in the concrete together with the second main steel member, and a connecting reinforcing bar portion that connects the joint reinforcing bar portion and the second joint reinforcing bar portion.

[0010] The structure may further comprise a plurality of steel units each including a main steel material and a second main steel material arranged in a direction perpendicular to the longitudinal direction, each having a joint reinforcing bar portion, a second joint reinforcing bar portion and a connecting reinforcing bar portion, each arranged corresponding to each connection portion between each steel unit, and a second connecting reinforcing bar portion extending in a direction intersecting the longitudinal direction at a position farther from the precast concrete slab than the second main steel material and connecting the plurality of small reinforcing bar units together.

[0011] The joint construction method of the present invention is a joint construction method for constructing a joint structure that connects structural steel beams to be embedded in concrete, in which a joint reinforcing bar portion is placed near the connection between the structural steel beams so that it extends longitudinally across both ends of the structural steel beams that are connected to each other longitudinally, and concrete is poured to bury the joint reinforcing bar portion and the structural steel beams together. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a joint structure and a joint construction method that enable a joint to be easily constructed between structural steel beams that are embedded in concrete. [Brief explanation of the drawings]

[0013] [Figure 1] 1(a) is an exploded perspective view showing the composite half precast member and the reinforcing bar cage in the joint structure of the first embodiment, and FIG. 1(b) is a side view showing them as seen from the Y direction. [Figure 2] 10A is a side view showing the composite half precast member and the reinforcing bar cage in the joint structure of the second embodiment, and FIG. 10B is a side view showing the composite half precast member and the reinforcing bar cage in the joint structure of the third embodiment, as viewed from the Y direction. [Figure 3] FIG. 10(a) is a perspective view showing a composite half precast member and a reinforcing bar cage in a joint structure of a fourth embodiment, and FIG. 10(b) is a side view showing them as viewed in the Y direction. [Figure 4] FIG. 10(a) is a perspective view showing a composite half precast member and a reinforcing bar cage in a joint structure of a fifth embodiment, and (b) is a side view showing them as viewed in the Y direction. [Figure 5] FIG. 10(a) is a perspective view showing a composite half precast member and a reinforcing bar cage in a joint structure of a sixth embodiment, and (b) is a side view showing them as viewed in the Y direction. [Figure 6] FIG. 13(a) is a perspective view showing a composite half precast member and a reinforcing bar cage in a joint structure of a seventh embodiment, and (b) is a side view showing them as viewed in the Y direction. [Figure 7] FIG. 13(a) is a perspective view showing a composite half precast member and a reinforcing bar cage in a joint structure of an eighth embodiment, and (b) is a side view showing them as viewed in the Y direction. [Figure 8] FIG. 13(a) is a perspective view showing a composite half precast member and a reinforcing bar cage in a joint structure of the ninth embodiment, and (b) is a side view showing them as viewed in the Y direction. [Figure 9] A side view showing a composite half precast member and a reinforcing bar cage in a joint structure related to a modified example of the ninth embodiment, as viewed from the Y direction. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of a joint structure and a joint construction method according to the present invention will be described in detail with reference to the drawings. In the following, identical or equivalent components will be designated by the same reference numerals, and redundant description will be omitted.

[0015] (First embodiment) The joint structure 1 and joint construction method of this embodiment are applied to the connection between composite half-precast members 3 shown in Figure 1. In the following, an XYZ Cartesian coordinate system is set as shown in the figure, and X, Y, and Z may be used to explain the positional relationship of each part. Furthermore, when terms such as "upper / lower" and "top / bottom" are used below, they correspond to the top and bottom of the composite half-precast member 3 in the position shown in Figure 1, with the +Z direction being vertically upward and the -Z direction being vertically downward. Furthermore, the features of the components may be depicted exaggerated in the drawings, and the dimensional ratios of the components, etc. in the drawings do not necessarily match those of the actual components, and they do not necessarily match between the drawings.

[0016] The composite half-precast member 3 includes a rectangular precast concrete slab 5 that functions as an embedded formwork, and a steel unit 7 fixed to the precast concrete slab 5. The precast concrete slab 5 is a flat plate with a thickness in the Z direction, and is rectangular in plan view with a short side extending in the X direction and a long side extending in the Y direction. The steel unit 7 is provided to rise vertically upward from the surface 5a of the precast concrete slab 5 and includes two main steel members 11 and 12 and a connector 15 that connects the main steel members 11 and 12. When distinguishing between the main steel members, one is referred to as the lower main steel member 11 (main steel member) and the other is referred to as the upper main steel member 12 (second main steel member). The composite half-precast member 3 includes two steel units 7 aligned in the X direction. The steel units 7 may be joined to the precast concrete slab 5 using a known joining structure.

[0017] The lower main steel member 11 extends straight in the Y direction along the surface 5a of the precast concrete slab 5. The upper main steel member 12 extends straight in parallel to the lower main steel member 11 at a position farther away from the precast concrete slab 5 in the Z direction than the lower main steel member 11. The lower main steel member 11 and the upper main steel member 12 are composed of shaped steel members extending straight in the Y direction. In the example shown in the figure, the shaped steel members used as the main steel members 11, 12 are flat steel members, but the main steel members 11, 12 are not limited to flat steel members and may also be composed of angle steel members, H-shaped steel members, C-shaped steel members, L-shaped steel members, CT-shaped steel members, etc. The lower main steel member 11 and the upper main steel member 12 extend over the entire length of the precast concrete slab 5 in the Y direction. The connecting members 15 include shear reinforcement bars that connect the lower main steel members 11 and the upper main steel members 12 in the Z direction, diagonal members that connect them at an angle, etc., but to avoid complicating the drawing, most of these are omitted and only a portion is shown. The lower main steel members 11, the upper main steel members 12, and the connecting members 15 are connected to each other by welding or the like to form an integrated steel unit 7.

[0018] The composite half-precast members 3 described above are connected in the X and Y directions, and concrete 17 (see Figure 1(b)) is poured onto the surface 5a of the precast concrete slabs 5 to construct a steel-reinforced concrete structure with steel units 7 embedded within. Because the composite half-precast members 3 themselves have high rigidity, shoring on the underside and sides of the formwork can be omitted during the construction of this structure. In constructing the structure described above, waterproofing is performed between adjacent precast concrete slabs 5, 5 in preparation for concrete pouring. At the joints between adjacent steel units 7, 7, the ends of the lower main steel members 11, 11 are positioned face-to-face, and the ends of the upper main steel members 12, 12 are positioned face-to-face. The lower main steel members 11, 11 and the upper main steel members 12, 12 must be connected longitudinally (in the Y direction) using appropriate joint structures that enable stress transfer.

[0019] The following describes the joint structure 1 between the lower main steel members 11, 11 and between the upper main steel members 12, 12, and the joint construction method for constructing this joint structure 1. In the following description, the connection between the composite half precast members 3, 3 adjacent in the Y direction is referred to as the "connection portion 3P," and the connection portion between the precast concrete slabs 5, 5 within the connection portion 3P is referred to as the "connection portion 5P." Additionally, the connection portion between the steel units 7, 7 adjacent in the Y direction is referred to as the "connection portion 7P," the connection portion between the lower main steel members 11, 11 within the connection portion 7P is referred to as the "connection portion 11P," and the connection portion between the upper main steel members 12, 12 within the connection portion 7P is referred to as the "connection portion 12P."

[0020] The joint structure 1 is constructed using a reinforcing bar cage 20 shown in Figures 1(a) and (b). Figure 1(a) is an exploded perspective view showing the composite half precast members 3, 3 and the reinforcing bar cage 20 in the joint structure 1 of this embodiment, and (b) is a side view of the joint structure 1 as viewed in the Y direction. In Figure 1(a), to avoid complicating the illustration, only one set of composite half precast members 3, 3 adjacent in the Y direction is shown, and only one unit of the reinforcing bar cage 20 corresponding to this set is shown. In reality, these sets of composite half precast members 3, 3 and units of the reinforcing bar cage 20 are repeated many times in a row in the X direction.

[0021] The reinforcing bar cage 20 includes a joint reinforcing bar portion 21 and a joint reinforcing bar portion 22 arranged in parallel. The joint reinforcing bar portion 21 extends in the Y direction and is arranged in a range in the Y direction that spans both ends of the connected lower main steel members 11, 11, and is arranged near the connecting portion 11P. In the Y direction, the center of the joint reinforcing bar portion 21 may be located at the position of the connecting portion 11P. The joint reinforcing bar portion 21 is located immediately adjacent to the lower main steel members 11, 11 but shifted in the X direction. It may be in contact with the lower main steel members 11, 11, or there may be a small gap in the X direction between the joint reinforcing bar portion 21 and the lower main steel members 11, 11. Similarly, the joint reinforcing bar portion 22 (second joint reinforcing bar portion) extends in the Y direction and is arranged in a range in the Y direction that spans both ends of the connected upper main steel members 12, 12, and is arranged near the connecting portion 12P. In the Y direction, the center of the joint reinforcing bar part 22 may be located at the position of the connecting part 12P. The joint reinforcing bar part 22 is located immediately adjacent to the upper main steel members 12, 12 but shifted in the X direction, and may be in contact with the upper main steel members 12, 12, or there may be a small gap in the X direction between the joint reinforcing bar part 22 and the upper main steel members 12, 12.

[0022] The joint reinforcing bar portions 21, 22 are made of reinforcing bars extending in the Y direction, and anchoring portions 21a, 22a are provided at both ends of the joint reinforcing bar portions 21, 22 to improve anchoring performance to the concrete 17. In the illustrated example, the anchoring portions 21a, 22a are semicircular hook portions formed by bending both ends of the joint reinforcing bar portions 21, 22 into a semicircular hook shape. In the illustrated example, the semicircular hook portions are curved in a plane perpendicular to the X direction, but they may also be curved in a plane parallel to the surface 5a of the precast concrete slab 5. Furthermore, the semicircular hook portions in the illustrated example may be inverted upside down. Furthermore, the anchoring portions 21a, 22a are not limited to such semicircular hook portions and may be, for example, mechanical anchoring portions provided at both ends of the straight joint reinforcing bar portions 21, 22.

[0023] The reinforcing bar cage 20 further includes a connecting reinforcing bar portion 23 and a second connecting reinforcing bar portion 25. The connecting reinforcing bar portion 23 extends linearly in the Z direction and connects the joint reinforcing bar portion 21 and the joint reinforcing bar portion 22. The connecting reinforcing bar portion 23 may also function as a shear reinforcement bar in the final completed steel-framed concrete structure. The second connecting reinforcing bar portion 25 may also function as a distribution bar in the final completed steel-framed concrete structure. In the example shown in the figure, the joint reinforcing bar portion 21 and the joint reinforcing bar portion 22 are connected by two connecting reinforcing bar portions 23, 23 that are arranged in parallel and offset in the Y direction. If a unit consisting of the joint reinforcing bar part 21, the joint reinforcing bar part 22, and the two connecting reinforcing bar parts 23, 23, which are connected and integrated together as described above, is called a "reinforcing bar sub-unit 27," then in the joint structure 1, one reinforcing bar sub-unit 27 is placed near each connecting part 7P. Then, these multiple reinforcing bar sub-units 27 lined up in the X direction are continuously connected to each other by second connecting reinforcing bar parts 25, 25.

[0024] The second connection reinforcing bar portion 25 is positioned farther from the precast concrete slab 5 than the upper main steel member 12, and extends linearly in the X direction. In the example shown in the figure, the reinforcing bar cage 20 includes two second connection reinforcing bar portions 25, 25 positioned in parallel and offset in the Y direction. A plurality of reinforcing bar sub-units 27 are connected to each other by the two second connection reinforcing bar portions 25, 25. Each second connection reinforcing bar portion 25, 25 passes immediately adjacent to the intersection of the joint reinforcing bar portion 22 and the connection reinforcing bar portions 23, 23. The joint reinforcing bar portions 21, 22, the connection reinforcing bar portions 23, 23, and the second connection reinforcing bar portions 25, 25 as described above are connected to each other by wire or the like to form the reinforcing bar cage 20.

[0025] It can be said that the above-described configuration of the reinforcing bar cage 20 is such that the multiple joint reinforcing bar parts 21 arranged for the multiple connection parts 11P are connected to each other via the connection reinforcing bar parts 23, 23 and the second connection reinforcing bar parts 25, 25 at a position farther from the precast concrete slab 5 than the lower main steel material 11. In other words, if the joint reinforcing bar parts 22 are omitted from the steel material unit 7, the joint reinforcing bar parts 22 of the reinforcing bar cage 20 may be omitted.

[0026] Next, with reference to FIG. 1, a joint construction method for constructing a joint structure 1 using the reinforcing bar cage 20 described above will be described. In this construction method, multiple composite half precast members 3 are first positioned corresponding to the position of the steel-reinforced concrete structure to be constructed. The precast concrete slabs 5 of each composite half precast member 3 are then arranged two-dimensionally in the X and Y directions, and waterproofing treatment is applied between adjacent precast concrete slabs 5 in the X and Y directions. As described above, in the composite half precast members 3, 3 adjacent in the Y direction, at the connection portions 7P between the steel units 7, 7, the ends of the lower main steel members 11, 11 are positioned end-to-end, and the ends of the upper main steel members 12, 12 are positioned end-to-end. Although only two connection portions 7P are shown in FIG. 1(a), in reality, many connection portions 7P are repeatedly and continuously present in the X direction.

[0027] Meanwhile, the aforementioned reinforcing bar cage 20 is prepared using reinforcing bars, wire, etc. As mentioned above, in FIG. 1(a), only two sub-reinforcing bar units 27 of the reinforcing bar cage 20 are shown corresponding to the two connecting portions 7P, but in the actual reinforcing bar cage 20, many sub-reinforcing bar units 27 are repeatedly arranged continuously in the X direction. Then, the reinforcing bar cage 20 is installed on the surface 5a of the precast concrete slab 5 in the positional relationship shown in FIG. 1(b), with each sub-reinforcing bar unit 27 of the constructed reinforcing bar cage 20 aligned with each steel unit 7.

[0028] Next, the precast concrete slabs 5 of the composite half precast member 3 are used as buried formwork, and with any necessary formwork (not shown) installed, concrete 17 is poured into these formworks. The concrete 17 is poured onto the surface 5a of the precast concrete slabs 5 to a height that buries all of the steel units 7 and reinforcing bar cages 20, and finally the steel units 7 and reinforcing bar cages 20 are buried together in the hardened concrete 17.

[0029] This completes the construction of a steel-concrete structure with the steel units 7 embedded therein, and the joint structure 1. The joint structure 1 includes joint reinforcing bar parts 21 embedded in the concrete 17 together with the lower main steel members 11, 11, and joint reinforcing bar parts 22 embedded in the concrete 17 together with the upper main steel members 12, 12.

[0030] In this joint structure 1, the joint reinforcing bar portions 21 extend in the Y direction so as to wrap around both ends of the lower main steel members 11, 11, and are embedded in the concrete 17 together with the lower main steel members 11, 11 near the connecting portion 11P, thereby constructing a joint that allows stress to be transmitted between the lower main steel members 11, 11 via the joint reinforcing bar portions 21 and the concrete 17. Similarly, the joint reinforcing bar portions 22 extend in the Y direction so as to wrap around both ends of the upper main steel members 12, 12, and are embedded in the concrete 17 together with the upper main steel members 12, 12 near the connecting portion 12P, thereby constructing a joint that allows stress to be transmitted between the upper main steel members 12, 12 via the joint reinforcing bar portions 22 and the concrete 17. Here, the rebar thickness and Y-direction length of the joint rebar sections 21, 22, their positional relationship with the connecting sections 11P, 12P, the specifications of the anchoring sections 21a, 22a, etc. may be appropriately designed so as to enable the necessary stress transmission between the lower main steel sections 11, 11 and between the upper main steel sections 12, 12.

[0031] The effects of the joint structure 1 described above are explained below. If friction joints or welded joints were used to connect the lower main steel members 11, 11 and the upper main steel members 12, 12, the construction would require a large amount of on-site work and the precise installation of the main steel members would be a factor in impairing workability. Furthermore, if the spacing between the steel units 7 in the X direction is narrow, work inside the composite half precast member 3 would be difficult, and it may be impossible to construct friction joints or welded joints. A lap joint structure, in which the ends of the lower main steel member 11 and the upper main steel member 12 are overlapped to transfer stress, could also be considered. However, this requires the lower main steel member 11 and the upper main steel member 12 to protrude in the Y direction from the precast concrete slab 5, potentially reducing workability during installation of the composite half precast member 3. While a joint structure using joint steel is also possible, this increases the likelihood of improper filling of the concrete 17 into the joint and increases the cost of the joint. In contrast, when constructing the joint structure 1, it is sufficient to install the joint reinforcing bar parts 21, 22 along the vicinity of the connecting parts 11P and 12P before pouring the concrete 17, so the joint structure 1 can be constructed easily and at low cost, and installation errors can be absorbed within the space between the joint reinforcing bar parts 21, 22 and the connecting parts 11P and 12P, making construction easy. Furthermore, the joint structure 1 can use ordinary deformed reinforcing bars that do not require special processing, which also contributes to cost reduction.

[0032] Furthermore, multiple joint reinforcing bars 21, 22 aligned in the X direction are integrated as a reinforcing bar cage 20 via connecting reinforcing bars 23 and second connecting reinforcing bars 25. Therefore, simply installing the reinforcing bar cage 20 along the connecting portions 3P between the composite half precast members 3 allows multiple joint reinforcing bars 21, 22 to be aligned along each connecting portion 11P, 12P. This reduces on-site work and improves construction efficiency. In particular, because the steel unit 7 includes two main steel members, the lower main steel member 11 and the upper main steel member 12, it is difficult to position the joint reinforcing bars 22 at the connecting portion 12P located away from the precast concrete slab 5. However, with the joint structure 1, installing the reinforcing bar cage 20 makes it relatively easy to position the joint reinforcing bars 22 near the connecting portion 12P.

[0033] (Second embodiment) The spacing between the joint reinforcing bar portions 21, 22 and the main steel members 11, 12 may be changed depending on the required structural performance of the joint, the joint length, the amount of reinforcing bar required, etc. For example, in the joint structure 201 of this embodiment shown in FIG. 2(a), the reinforcing bar sub-units 27 are arranged offset in the X direction compared to the joint structure 1 (FIG. 1). In the X direction, the joint reinforcing bar portion 21 is located approximately in the center between adjacent connecting portions 11P, 11P, and the joint reinforcing bar portion 22 is located approximately in the center between adjacent connecting portions 12P, 12P. Note that in FIG. 2 and subsequent figures, the concrete 17 (FIG. 1(b)) in which the main steel members 11, 12 and the joint reinforcing bar portions 21, 22 are embedded is omitted from illustration to avoid complication.

[0034] (Third embodiment) In addition, the numbers of joint reinforcing bar parts 21, 22, connection reinforcing bar part 23, and second connection reinforcing bar part 25 in the reinforcing bar cage 20 may be changed as appropriate. For example, in the joint structure 301 of this embodiment shown in Fig. 2(b), two reinforcing bar sub-units 27 are arranged immediately adjacent to one connecting part 7P so as to sandwich the connecting part 7P in the X direction. Then, two joint reinforcing bar parts 21 are arranged immediately adjacent to one connecting part 11P so as to sandwich the connecting part 11P in the X direction, and two joint reinforcing bar parts 22 are arranged immediately adjacent to one connecting part 12P so as to sandwich the connecting part 12P in the X direction.

[0035] (Fourth embodiment) Furthermore, multiple joint reinforcing bar portions 21 may be arranged in parallel to one connecting portion 11P, and multiple joint reinforcing bar portions 22 may be arranged in parallel to one connecting portion 12P. This makes it easier to secure the amount of steel required for the joint even when using relatively thin reinforcing bars, and reduces the length of the joint reinforcing bar portions 21, 22 in the Y direction. Furthermore, the joint reinforcing bar portions 21, 22 may be arranged in an appropriate direction depending on the relationship between the distance between the joint reinforcing bar portions 21, 22 and the cover. This makes it possible to suppress the occurrence of bond splitting cracks and improve the stress transmission performance of the joint structure. For example, in the joint structure 401 of this embodiment shown in FIGS. 3(a) and 3(b), a reinforcing bar cage 420 is used instead of the reinforcing bar cage 20 of the first embodiment. In the reinforcing bar cage 420, multiple joint reinforcing bar portions 21 (three in the illustrated example) are arranged in parallel in the Z direction near the connecting portion 11P. Similarly, a plurality of (three in the illustrated example) joint reinforcing bar portions 22 are arranged in parallel in the Z direction near the connecting portion 12P. Furthermore, the anchoring portions 21a, 22a of the joint reinforcing bar portions 21, 22 in the first embodiment (FIG. 1) are curved in a plane perpendicular to the X direction, whereas the anchoring portions 21a, 22a of the joint reinforcing bar portions 21, 22 in FIG. 3 are curved in a plane parallel to the surface 5a of the precast concrete slab 5. The plurality of joint reinforcing bar portions 21 and the plurality of joint reinforcing bar portions 22 are connected to each other via two connecting reinforcing bar portions 23, 23.

[0036] (Fifth embodiment) When multiple joint reinforcing bar parts 21, 22 are installed for one connecting portion 11P, 12P, joint reinforcing bar parts 21, 22 having different Y-direction lengths or different orientations of anchoring parts 21a, 21b may be mixed to avoid interference between the joint reinforcing bars and to distribute damage within the joint. For example, in a joint structure 501 of this embodiment shown in FIGS. 4(a) and 4(b), a reinforcing bar cage 520 is used instead of the reinforcing bar cage 20 of the first embodiment. In the reinforcing bar cage 520, two joint reinforcing bar parts 21 (joint reinforcing bar parts 21s, 21t) are arranged near the connecting portion 11P, and two joint reinforcing bar parts 22 (joint reinforcing bar parts 22s, 22t) are arranged near the connecting portion 12P. The joint reinforcing bar parts 21t, 22t extend longer in the Y direction than the joint reinforcing bar parts 21s, 22s. Furthermore, the anchoring portions 21a, 22a of the joint reinforcing bar portions 21s, 22s are semicircular hook portions that curve in a plane perpendicular to the X direction, and the anchoring portions 21a, 22a of the joint reinforcing bar portions 21t, 22t are semicircular hook portions that curve in a plane parallel to the surface 5a of the precast concrete slab 5. In this way, the lengths and orientations of the anchoring portions 21a, 22a of the joint reinforcing bar portion 21s and the joint reinforcing bar portion 21t are different, so interference between the joint reinforcing bar portions 21s, 21t can be avoided. Similarly, interference between the joint reinforcing bar portion 22s and the joint reinforcing bar portion 22t can also be avoided.

[0037] Furthermore, in the reinforcing bar cage 520, one small reinforcing bar unit 27 has four connecting reinforcing bar portions 23. Two of these connecting reinforcing bar portions 23s, 23s are located at both ends of the joint reinforcing bar portions 21s, 22s in the Y direction. These connecting reinforcing bar portions 23s, 23s connect the joint reinforcing bar portions 21s, 22s to each other and also connect the joint reinforcing bar portions 21t, 22t to each other. The remaining two connecting reinforcing bar portions 23t, 23t are located at both ends of the joint reinforcing bar portions 21t, 22t in the Y direction, and these connecting reinforcing bar portions 23t, 23t connect the joint reinforcing bar portions 21t, 22t to each other.

[0038] (Sixth embodiment) The joint reinforcing bar portions 21, 22 may be part of a hoop. For example, in a joint structure 601 of this embodiment shown in FIGS. 5(a) and 5(b), a reinforcing bar cage 620 is used instead of the reinforcing bar cage 20 of the first embodiment. In the reinforcing bar cage 620, the reinforcing bar sub-unit 27 is composed of one hoop 31. The hoop 31 is formed by bending a reinforcing bar and joining both ends to form a ring shape, and has a rectangular hoop shape with two sides extending in the Y direction and two sides extending in the Z direction. One side of the hoop 31 extending in the Y direction is positioned near the connecting portion 11P to form the joint reinforcing bar portion 21, and the other side extending in the Y direction is positioned near the connecting portion 12P to form the joint reinforcing bar portion 22. Furthermore, the two sides 23j, 23j of the hoop 31 extending in the Z direction connect the joint reinforcing bar parts 21, 22 together instead of the connection reinforcing bar part 23 (see FIG. 1). The two sides 23j, 23j are provided at both ends of the joint reinforcing bar parts 21, 22 and also function as anchoring parts that improve the anchoring performance of the joint reinforcing bar parts 21, 22 to the concrete 17. A plurality of such hoops 31 are provided corresponding to each connecting part 7P and are lined up in the X direction, and the plurality of hoops 31 are connected to each other via the second connection reinforcing bar parts 25, 25. In this way, by configuring the joint reinforcing bar parts 21, 22 as part of the hoops, the assembly of the reinforcing bar cage is labor-saving.

[0039] Seventh embodiment Furthermore, the hoops including the joint reinforcing bar portions 21, 22 may extend in a plane parallel to the precast concrete slab 5. For example, in the joint structure 701 of this embodiment shown in FIGS. 6(a) and 6(b), a reinforcing bar cage 720 is used instead of the reinforcing bar cage 20 of the first embodiment. The reinforcing bar cage 720 has two types of hoops 33, 35 arranged in parallel, and the hoops 33, 35 form a rectangular hoop shape with two sides extending in the Y direction and two sides extending in the X direction. The hoops 33, 35 are sandwiched in the X direction between adjacent connecting portions 7P and other connecting portions 7P. One hoop 33 is sandwiched in the X direction between connecting portions 11P, 11P, and the other hoop 35 is sandwiched in the X direction between connecting portions 12P, 12P.

[0040] One side of the hoop 33 extending in the Y direction is placed near one connecting portion 11P that sandwiches the hoop 33, forming a joint reinforcing bar portion 21. The other side of the hoop 33 extending in the Y direction is placed near the other connecting portion 11P that sandwiches the hoop 33, forming a joint reinforcing bar portion 21. Similarly, one side of the hoop 35 extending in the Y direction is placed near one connecting portion 12P that sandwiches the hoop 35, forming a joint reinforcing bar portion 22. The other side of the hoop 35 extending in the Y direction is placed near the other connecting portion 12P that sandwiches the hoop 35, forming a joint reinforcing bar portion 22.

[0041] The hoops 33, 35 are connected to each other by four connecting reinforcing bar parts 23 extending in the Z direction, and each connecting reinforcing bar part 23 connects the joint reinforcing bar part 21 and the joint reinforcing bar part 22. In addition, of the hoops 33, 35, two sides 71j, 71j extending in the X direction are provided at both ends of the joint reinforcing bar parts 21, 22 in the Y direction and also function as anchoring parts that improve the anchoring performance of the joint reinforcing bar parts 21, 22 to the concrete 17.

[0042] (Eighth embodiment) Furthermore, to prevent bearing failure of the anchoring portions of the joint reinforcing bar portions 21, 22, reinforcing steel may be inserted into the hoops as described above. For example, in a joint structure 801 of this embodiment shown in FIGS. 7(a) and 7(b), a reinforcing bar cage 820 is used instead of the reinforcing bar cage 20 of the first embodiment. The reinforcing bar cage 820 is configured by replacing the hoops 33, 35 of the reinforcing bar cage 620 (FIG. 6) with hoops 37, 39, which have a slightly different hoop shape. The hoops 37, 39 have two arc-shaped connection portions 73j, 73j curved in a semicircular arc instead of the two sides 71j, 71j (FIG. 6(a)) of the aforementioned hoops 33, 35. That is, the two joint reinforcing bar sections 21 of the hoop reinforcement 37 are connected at both ends by arc connection sections 73j, 73j, and similarly, the two joint reinforcing bar sections 22 of the hoop reinforcement 39 are connected at both ends by arc connection sections 73j, 73j.

[0043] Meanwhile, a circular steel pipe 41 is provided on the surface 5a of the precast concrete slab 5 in the joint structure 801 as the reinforcing steel member, rising in the Z direction near the connecting portion 7P. The steel pipe 41 is joined to the precast concrete slab 5 using a predetermined known structure with its pipe axis facing the Z direction. The upper end of the steel pipe 41 is located slightly higher than the upper main steel member 12. When the reinforcing bar cage 820 is installed on the precast concrete slab 5, the reinforcing bar cage 820 is guided and positioned by two steel pipes 41, 41 located near the connecting portion 7P, and is installed on the precast concrete slab 5 with the steel pipes 41, 41 inserted into the hoops 37, 39. The upper end of the steel pipe 41 protrudes in the Z direction, passing through the area surrounded by the arc connection portion 73j of the hoop 39 and the second connection reinforcing bar portion 25. In addition, at this time, it is preferable that the entire arc-shaped connecting portions 73j, 73j of the hoop reinforcements 37, 39 be in close contact with the outer circumferential surface of the steel pipe 41. In other words, it is preferable that the radius of curvature of the arc-shaped connecting portions 73j, 73j and the position of the steel pipe 41 are set so that such a positional relationship is satisfied.

[0044] The presence of the steel pipes 41 as described above can greatly increase the resistance of the steel-concrete structure to bearing failure. In particular, if the arc-shaped connections 73j, 73j are in tight contact along the outer periphery of the steel pipes 41 as described above, the resistance to bearing failure is even greater. Furthermore, the presence of the steel pipes 41 in the precast concrete slab 5 allows the reinforcing bar cage 820 to be installed by fitting the hoops 37, 39 into the steel pipes 41 as a guide, making it easy to align the reinforcing bar cage 820.

[0045] Note that it is not necessary for the steel pipe 41 to be joined to the precast concrete slab 5 in advance. The steel pipes 41, 41 may be pre-fixed to the reinforcing bar cage 820, for example, by being fixed to the hoops 37, 39. In this case, the efficiency of the installation work for installing the joint reinforcing bar parts 21, 22 is improved, and the accuracy of the placement of each component, such as the positional relationship between the joint reinforcing bar parts 21, 22 and the main steel members 11, 12 and the positional relationship between the joint reinforcing bar parts 21, 22 themselves, is improved. Alternatively, after the reinforcing bar cage 820 is installed in the precast concrete slab 5, the steel pipe 41 may be installed inside the hoops 37, 39 so as to align with the arc connection part 73j. Furthermore, even if the reinforcing bars constituting the joint reinforcing bar parts 21, 22 are not the hoops 37, 39 but reinforcing bars with hook-shaped ends, similar effects can be expected by installing the steel pipe 41 inside the hook parts of the reinforcing bars. Moreover, instead of the steel pipe 41, reinforcing bars or square steel pipes may be used as the reinforcing steel material.

[0046] (Ninth embodiment) To improve the anchorage of the main steel members 11 and 12 at the joint, steel members may be added to resist the bulging of concrete around the main steel members 11 and 12 that occurs when the joint is damaged. Adding such steel members allows the joint length of the main steel members 11 and 12 to be shortened, resulting in a more rational joint structure. For example, in a joint structure 901 of this embodiment shown in FIGS. 8(a) and 8(b), a reinforcing bar cage 920 is used instead of the reinforcing bar cage 20 of the first embodiment. The reinforcing bar cage 920 is the aforementioned reinforcing bar cage 720 with the addition of a reinforcing bar 45. The reinforcing bar 45 is located inside the hoops 33 and 35 at the center of the hoops 33 and 35 in the Y direction. The reinforcing steel bar 45 has an overall U-shape in a plane perpendicular to the Y direction, spanning adjacent joint steel bar portions 21 and adjacent joint steel bar portions 22.

[0047] At both ends in the X direction of the reinforcing steel bar 45, there are straight portions 45a that extend in the Z direction and contact the inside of the hoops 33, 35. The ends of these straight portions 45a are connected via connecting portions 45b that extend in the X direction at a position higher than the upper main steel material 12. The straight portions 45a are connected to the joint reinforcing bar part 21 and the joint reinforcing bar part 22, respectively.

[0048] According to this joint structure 901, the rigidity of the hoops 33, 35 in the direction in which they crush in the X direction is improved by the presence of the reinforcing steel 45. Furthermore, the rigidity of the reinforcing steel 45 inside the hoops 33, 35 can resist the behavior of the concrete 17 around the lower main steel member 11 and the upper main steel member 12 bulging out, so a restraining effect on the joint reinforcing steel parts 21 and 22 and an improvement in anchorage performance due to this restraining effect can be expected.

[0049] For example, instead of providing the reinforcing steel bars 45 in the reinforcing steel cage 920, the reinforcing steel bars 45 may be embedded in advance in the precast concrete slab 5. In this case, the reinforcing steel bars 45 can be used for positioning when installing the reinforcing steel cage 920 in the precast concrete slab 5. Also, after the reinforcing steel cage 920, excluding the reinforcing steel bars 45, is installed in the precast concrete slab 5, the reinforcing steel bars 45 may be assembled in place.

[0050] 9, the reinforcing steel bars 45 may be offset in the X direction so that they straddle adjacent hoops 33 and hoops 35. In this case, one of the linear portions 45a of the reinforcing steel bars 45 is connected to the joint reinforcing steel portion 21 of the hoop 33 and the joint reinforcing steel portion 22 of the hoop 35, and the other linear portion 45a of the reinforcing steel bars 45 is connected to the joint reinforcing steel portion 21 of the adjacent hoop 33 and the joint reinforcing steel portion 22 of the adjacent hoop 35. The reinforcing steel bars 45 may also be extended in the X direction so that they straddle multiple hoops 33 and 35. A plurality of reinforcing steel bars 45 may also be installed so that they are lined up in the Y direction inside the hoops 33 and 35.

[0051] 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. Furthermore, the following modifications can also be constructed by utilizing the technical matters described in the above-described embodiment. The various configurations of the embodiments and modifications may be used in appropriate combination.

[0052] The number of reinforcing bars (joint reinforcing bar sections 21, 22, connecting reinforcing bar section 23, second connecting reinforcing bar section 25, etc.) that make up the reinforcing bar cage shown in each embodiment is not limited to the examples shown in the figures, and can be changed as appropriate depending on the design concept.

[0053] Components for improving the anchoring performance of the lower main steel member 11 and the upper main steel member 12 may be added to the joint structure in each embodiment as appropriate. Such components may include, for example, protrusions or anti-slip devices (e.g., headed studs, PBLs, etc.) provided on the surfaces of the lower main steel member 11 and the upper main steel member 12 near the connecting portions 11P, 12P. Also, anchors may be provided at the anchoring ends of the lower main steel member 11 and the upper main steel member 12. Bearing plates may be provided at the ends of the lower main steel member 11 and the upper main steel member 12.

[0054] It is not essential that the joint reinforcing bar part 21 and the joint reinforcing bar part 22 are connected by the connecting reinforcing bar part 23, and the joint reinforcing bar part 21 and the joint reinforcing bar part 22 may be independent of each other. In addition, it is not essential that the reinforcing bar small units 27 are connected to each other by the second connecting reinforcing bar part 25, and each reinforcing bar small unit 27 may be independent of each other.

[0055] To improve the performance of the joint, predetermined joint reinforcement bars may be added in place after the reinforcing bar cage is installed in the precast concrete slab 5. Furthermore, to improve the efficiency of installing the reinforcing bar cage in the precast concrete slab 5, alignment protrusions or the like may be provided on the main steel members 11 and 12 as markers and used to align the reinforcing bar cage. Furthermore, the reinforcing bar cage may be installed in the precast concrete slab 5 using the protrusions or the like provided on the main steel members 11 and 12 as guides, and may be aligned to the precast concrete slab 5 by hooking onto the protrusions or the like. Furthermore, predetermined steel material may be embedded in the precast concrete slab 5 and used to align the reinforcing bar cage. The steel material may contribute to the reinforcement of the joint, and may be, for example, the aforementioned steel pipe 41 or reinforcing steel bar 45.

[0056] Furthermore, in the above-described embodiments, examples have been described in which the joint structure of the present invention is applied to joints between the main steel members 11 and 12 included in the composite half precast structural member 3. However, the present invention can also be applied to joints between steel members embedded in concrete. For example, when concrete is poured using a conventional formwork instead of a precast concrete slab 5, the present invention can also be applied to joints between structural steel members embedded in the concrete. Furthermore, in the above-described embodiments, joints between the main steel members in the composite half precast structural member 3 have been described as examples, but the joint structures of these embodiments can also be applied to joints between reinforcing bars. Furthermore, in the above-described embodiments, the lower main steel members 11 and the upper main steel members 12 are butted together in the X direction, but this structure is not limited thereto. That is, the lower main steel members 11 and the upper main steel members 12 may be overlapped at the connecting portions 11P and 12P or may be separated in the X direction.

[0057] When constructing a steel-concrete structure, pouring of concrete 17 in the joint structures of the first to ninth embodiments described above may be carried out separately from pouring of the other parts, either before or after pouring. In this case, it is possible to change the strength and type of concrete 17 in the joint parts from the concrete in the other parts. For example, by increasing the strength of the concrete 17 filled in the joint parts or mixing fiber into the concrete 17, it is possible to improve the adhesion characteristics of the main steel members 11, 12 and the joint reinforcing bar parts 21, 22, and to expect the effect of reducing the length of the joint parts. [Explanation of symbols]

[0058] 1,201,301,401,501,601,701,801,901...joint structure, 3...composite half precast member, 5...precast concrete slab, 5a...surface, 7...steel unit, 11...lower main steel (main steel, structural steel), 11P...connecting part, 12...upper main steel (second main steel, structural steel), 12P...connecting part, 17...concrete, 21,21s,21t...joint reinforcing bar part, 21a...anchoring part, 22,22s,22t...joint reinforcing bar part (second joint reinforcing bar part), 22a...anchoring part, 23,23s,23t...connecting reinforcing bar part, 23j...edge (connecting reinforcing bar part), 25...second connecting reinforcing bar part, 27...small reinforcing bar unit, 33,35,37,39...hoop reinforcement.

Claims

1. In a half-precast member comprising a precast concrete slab, a structural steel fixed to the precast concrete slab along the surface of the precast concrete slab, and a second structural steel provided parallel to the structural steel at a position further away from the precast concrete slab than the structural steel, the half-precast member has a joint structure that connects the structural steels embedded in concrete to each other and also connects the second structural steels embedded in concrete to each other, a joint reinforcing bar portion that is disposed in the vicinity of the connection portion between the shaped steels so as to extend in the longitudinal direction across both ends of the shaped steels that are connected to each other in the longitudinal direction, and that is embedded in the concrete together with the shaped steels; a second joint reinforcing bar portion that is disposed near a connection portion between the second shaped steels so as to extend in the longitudinal direction across both ends of the second shaped steels that are connected to each other in the longitudinal direction, and that is embedded in the concrete together with the second shaped steels; A joint structure comprising:

2. 2. The joint structure according to claim 1, wherein a plurality of the joint reinforcing bar portions are arranged in parallel with one of the connecting portions, and the joint reinforcing bar portions are connected to each other via other reinforcing bars.

3. 3. The joint structure according to claim 1, wherein both ends of the joint reinforcing bar part are provided with anchoring parts for improving anchoring performance to the concrete.

4. The joint structure according to claim 1 or 2, wherein the joint reinforcing bar portion forms a part of a hoop reinforcing bar.

5. The structural steel is a main steel member fixed to a precast concrete slab along a surface of the precast concrete slab in a composite half precast member having the precast concrete slab, The joint structure according to any one of claims 1 to 4, wherein the concrete is poured using the precast concrete slab as an embedded formwork.

6. A plurality of the connection portions between the main steel members are present along the surface of the precast concrete slab so as to be aligned in a direction perpendicular to the longitudinal direction, 6. A joint structure as described in claim 5, wherein a plurality of joint reinforcing bar portions respectively arranged for a plurality of said connecting portions are connected to each other at positions farther from the precast concrete slab than the main steel material.

7. A joint structure for connecting structural steel pieces embedded in concrete, a joint reinforcing bar portion that is disposed in the vicinity of a connection portion between the shaped steels so as to extend in the longitudinal direction across both ends of the shaped steels that are connected to each other in the longitudinal direction, and that is embedded in the concrete together with the shaped steels; The structural steel is a main steel member fixed to a precast concrete slab along a surface of the precast concrete slab in a composite half precast member having the precast concrete slab, The concrete is poured using the precast concrete slab as an embedded formwork, The composite half precast member further includes a second main steel member provided parallel to the main steel member at a position farther from the precast concrete slab than the main steel member, a second joint reinforcing bar portion that is disposed near a connection portion between the second main steel members so as to extend in the longitudinal direction across both ends of the second main steel members that are connected to each other in the longitudinal direction, and that is embedded in the concrete together with the second main steel members; A joint structure further comprising a connection reinforcing bar portion that connects the joint reinforcing bar portion and the second joint reinforcing bar portion.

8. a plurality of steel material units including the main steel material and the second main steel material are arranged in a direction perpendicular to the longitudinal direction, A plurality of reinforcing bar subunits each having the joint reinforcing bar portion, the second joint reinforcing bar portion, and the connection reinforcing bar portion, and each arranged corresponding to each connection portion between the steel units; 8. The joint structure described in claim 7, further comprising a second connecting reinforcing bar portion extending in a direction intersecting the longitudinal direction at a position farther from the precast concrete slab than the second main steel member and connecting multiple reinforcing bar small units together.

9. In a half-precast member comprising a precast concrete slab, a structural steel fixed to the precast concrete slab along the surface of the precast concrete slab, and a second structural steel provided parallel to the structural steel at a position further away from the precast concrete slab than the structural steel, a joint construction method for connecting the structural steels embedded in concrete to each other and for constructing a joint structure for connecting the second structural steels embedded in concrete to each other, comprising: A joint construction method in which a joint reinforcing bar portion is arranged near the connection portion between the structural steels so as to extend in the longitudinal direction across both ends of the structural steels that are connected to each other in the longitudinal direction, and a second joint reinforcing bar portion is arranged near the connection portion between the second structural steels so as to extend in the longitudinal direction across both ends of the second structural steels that are connected to each other in the longitudinal direction, and concrete is poured so as to bury the joint reinforcing bar portion, the structural steel, and the second structural steel together.

10. A joint construction method for connecting half precast members each including a precast concrete slab and a plurality of parallel structural steels fixed to the precast concrete slab along the surface of the precast concrete slab in the longitudinal direction of the structural steels, in which a joint structure between the structural steels is constructed at each connection portion between a plurality of sets of the structural steels, a joint reinforcing bar portion installation process in which joint reinforcing bar portions are installed in the vicinity of each of the connection portions so as to extend in the longitudinal direction across both ends of the structural steels that are connected to each other in the longitudinal direction; A concrete pouring step in which concrete is poured so as to embed each of the joint reinforcing bar parts and each of the structural steels together, In the joint reinforcing bar portion installation process, A joint construction method in which a reinforcing bar unit formed by connecting a plurality of the joint reinforcing bar parts via other reinforcing bars is prepared in advance, and the reinforcing bar unit is installed in a predetermined position.

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