Concrete Structures

Abstract

To use PC steel for sticking cast-in-place concrete on the end surface side of a PC slab.SOLUTION: A concrete structure 1 comprises: a precast member 2 having a lateral surface 4 and a longitudinal surface 5 that form an L shape; a PC slab 11 having PC steel 12 buried therein with the end of the PC slab 11 placed on the lateral surface 4 and the end surface of the PC slab 11 facing the longitudinal surface 5; and cast-in-place concrete 15 formed to be installed in contact with the upper surface of the PC slab 11. A squeezed-out part 13 of the PC slab 12 squeezed out from the end surface of the PC slab 11 is buried in the cast-in-place concrete 15 laid around between the longitudinal surface 5 and the end surface of the PC slab 11.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to concrete structures such as civil engineering structures and architectural structures, which include prestressed concrete panels with embedded prestressing steel bars and cast-in-place concrete that is poured in contact with the upper surface of the prestressed concrete panels. Note that precast concrete is simply called precast. Prestressed concrete is also called PC. [Background technology]

[0002] It is difficult to completely precast large concrete structures (such as box culverts used under high embankment conditions) due to the difficulty of transportation and the difficulty of joining when they are formed in sections. On the other hand, constructing them using cast-in-place concrete requires a long construction period. Therefore, the inventors are considering a combination of precast members, PC panels, and cast-in-place concrete.

[0003] Patent Document 1 discloses a box culvert 50 in which, as shown in Fig. 11(a), a precast concrete slab 53 (formwork member) is erected between the tops of haunches 52 protruding inward from precast sidewall members 51, reinforcing bars are placed on the precast concrete slab 53 and in the corners (joints), and cast-in-place concrete 55 is poured, forming a top plate with the precast concrete slab 53 and the cast-in-place concrete 55. The "corner" here refers to the rectangular parallelepiped portion between the upper end of the side wall and the side end of the top plate, and is also referred to as the "joint" (the term "joint" is used in this application).

[0004] In this box culvert 50, the connecting rebars 58 protruding from the PC slab 53 and the loop bars 57 (which overlap with the loop bars 56 protruding from the member 51) are embedded in the cast-in-place concrete 55 to adhere the PC slab 53 to the cast-in-place concrete 55. However, because the joints of this box culvert 50, which are the most important part of a rigid frame structure, are constructed by casting in place, the quality is not stable and there is a possibility that the construction may not comply with the Japan Road Association's "Specifications for Highway Bridges."

[0005] Therefore, the inventors have previously proposed a box culvert 60 as shown in Figure 11(b) (Patent Document 2), in which the wall is made up of precast wall members 61, the top plate includes a precast concrete plate 63 placed and erected on haunches 62 protruding inward from the two precast wall members 61, and cast-in-place concrete 65 formed on the precast concrete plate 63, the entire joint being part of the precast wall members 61, and there are no lap joints of reinforcing bars within the joint.

[0006] In this box culvert 60, cast-in-place concrete 65 is embedded into the rough-finished upper surface of the PC slab 63, and dowel bars 66 protruding upward from the PC slab 63 are embedded in the cast-in-place concrete 65, thereby achieving adhesion between the PC slab 63 and the cast-in-place concrete 65. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2008-223370 A (Patent No. 4877654) [Patent Document 2] JP 2020-105768 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the box culverts of Patent Documents 1 and 2, the PC steel members 54, 64 embedded in the PC plates 53, 63 are intended solely to apply prestress to the PC plates so that they can resist bending, and do not protrude from the end faces of the PC plates 53, 63 and are not involved in adhesion to the cast-in-place concrete 55, 65 on the end face side.

[0009] Therefore, the object of the present invention is to involve the PC steel in the adhesion of the cast-in-place concrete at the end face side of the PC steel plate in a concrete structure including a PC plate with embedded PC steel and cast-in-place concrete poured in contact with the upper surface of the PC steel plate. [Means for solving the problem]

[0010] [1] A prestressing steel plate with prestressing steel bars embedded in it. In a concrete structure including cast-in-place concrete formed in contact with the upper surface of the PC slab, A concrete structure characterized in that the protruding portion of the prestressing steel member extending beyond the end face of the prestressing plate is embedded in cast-in-place concrete that wraps around the end face of the prestressing plate.

[0011] [2] A precast member having an L-shaped horizontal surface and a vertical surface; A PC plate having PC steel embedded therein, the end of the PC plate being placed on the horizontal surface and the end face of the PC plate facing the vertical surface; In a concrete structure including cast-in-place concrete formed in contact with the upper surface of the PC slab, A concrete structure characterized in that the protruding portion of the PC steel member extending beyond the end face of the PC plate is embedded in cast-in-place concrete that has wrapped around between the vertical surface and the end face of the PC plate.

[0012] [3] In the above [2], the reinforcing bars protruding from the precast members may be embedded in the cast-in-place concrete.

[0013] [Effect] The protruding portion of the PC steel that protrudes from the end face of the PC plate is embedded in the cast-in-place concrete that has wrapped around the end face of the PC plate, so that it adheres to the cast-in-place concrete at the end face, and this adhesion contributes to strong integration between the PC plate and the cast-in-place concrete. Effect of the Invention

[0014] According to the present invention, in a concrete structure including a prestressing concrete panel in which prestressing steel is embedded and cast-in-place concrete poured in contact with the upper surface of the prestressing concrete panel, the prestressing steel can be involved in the adhesion of the cast-in-place concrete on the end face side of the prestressing concrete panel, thereby achieving strong integration between the prestressing concrete panel and the cast-in-place concrete. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 shows the components of the box culvert of Example 1, where (a) is a front view of the PC plate, (b) is a side view of the PC plate, (c) is a front view of the precast sidewall member, and (d) is a side view of the precast sidewall member. [Diagram 2] Figure 2 is a perspective view of the two precast sidewall members in place. [Diagram 3] Figure 3(a) is a front view of the PC panel placed on the precast side wall member, and (b) is a cross-sectional view taken along line IIIb-IIIb. [Figure 4] FIG. 4 is a perspective view of FIG. 3(a) seen obliquely. [Diagram 5] Figure 5(a) is a front view of the precast member when continuous reinforcing bars are connected, and (b) is a cross-sectional view taken along the line Vb-Vb. [Figure 6] FIG. 6 is a perspective view of FIG. 5(a) seen obliquely. [Figure 7] FIG. 7 is a partially enlarged perspective view of FIG. [Figure 8] Figure 8(a) is a front view of a single-section box culvert constructed by pouring in-situ concrete on the same PC slab, and (b) is a cross-sectional view taken along the line VIIIb-VIIIb. [Figure 9] FIG. 9 is a perspective view of FIG. 8(a) seen obliquely. [Figure 10] FIG. 10 is a perspective view of the double box culvert of the second embodiment. [Figure 11] FIG. 11(a) is a partial cross-sectional view of a box culvert of a conventional example (Patent Document 1), and (b) is a partial front view of a box culvert of another conventional example (Patent Document 2). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] 1. Concrete structures Examples of concrete structures include, but are not limited to, civil engineering structures such as box culverts, bridges, storage tanks, and paving slabs, and architectural structures such as floor structures.

[0017] 2. Precast components The precast members are compatible with concrete structures. For example, if the concrete structure is a box culvert, the precast members are precast sidewall members, and if the concrete structure is a bridge, the precast members are precast girders.

[0018] 3.PC steel material The PC steel members may be embedded in the PC plate using either the pretensioning method or the posttensioning method. In the case of pretensioned PC steel, the protruding portion is formed by cutting the part that protrudes from the end face of the PC plate (whereas normally this is cut at the end face of the PC plate after it is removed from the form). When using the post-tensioning method, the PC steel protruding from the end face of the PC plate is grasped and tensioned, and the protruding part is formed by fixing the same part to the end face of the PC plate with a nut, wedge, etc. and cutting it to the specified length.

[0019] The protruding length of the PC steel member is not particularly limited, but is preferably 30 mm or more in terms of increasing adhesion, and can be as long as space permits (there is no upper limit, but typically it is 200 mm or less). EXAMPLES

[0020] Next, an embodiment of the present invention will be described with reference to the drawings. Note that the structure, material, shape and dimensions of each part in the embodiment are merely examples and can be appropriately changed without departing from the spirit of the invention.

[0021] [Example 1] Example 1 shown in Figures 1 to 9 is a large (e.g., 3000 to 10000 mm long, 4000 to 17000 mm wide) single-section box culvert, the finished product of which is shown in Figures 8 and 9. This box culvert 1 is composed of two precast sidewall members 2, one on the left and one on the right, a precast bottom slab member 10 connected between the lower parts of the precast sidewall members 2, and a top slab made of a precast concrete slab 11 installed between the upper parts of the precast sidewall members 2 and cast-in-place concrete 15 poured in contact with the upper surface of the precast concrete slab 11.

[0022] (Precast sidewall member 2) The above-mentioned "joint" between the side wall and the top plate is entirely part of the precast side wall member 2, and there are no lap joints of reinforcing bars within the joint. The precast sidewall member 2 has a haunch 3 that protrudes inward, and the upper surface (horizontal surface 4) of the haunch 3 is at the same level as the lower end of the joint. Therefore, the horizontal surface 4 of the haunch 3 and the vertical surface 5, which is the inner surface of the joint, form an L shape in front view.

[0023] A plurality of mechanical joints 6 (for example, screw joints) are embedded near the vertical faces 5 of the joints, and the mechanical joints 6 are connected to reinforcing bars 7 embedded in the precast sidewall members 2 . Additionally, the bases of multiple anchoring rebars 8 are embedded in the haunch 3, and the action parts of the anchoring rebars 8 protrude upward from the side surface 4 of the haunch 3. An enlarged diameter part 9 having a diameter larger than that of the anchoring rebars 8 is provided at the upper end of the anchoring rebars 8 by screwing a nut or the like.

[0024] (Precast base member 10) The precast bottom slab member 10 constitutes the middle part of the bottom slab, and is joined to the lower part of the precast sidewall member 2 on-site with a mortar-filled joint (not shown). Note that the middle part of the bottom slab may be formed of cast-in-place concrete 15 instead of the precast bottom slab member 10.

[0025] (PC version 11) The PC slab 11 is made of precast concrete, and PC steel members 12 are placed and embedded in the concrete slab so as to resist bending during use, and prestress (compressive stress) is introduced to the lower edge by a pretensioning or posttensioning method. The PC steel members 12 have protruding portions 13 that protrude in the length direction from both end faces of the PC slab 11, and the protruding length of the protruding portions 13 is, for example, 30 to 100 mm.

[0026] The bases of a plurality of dowel reinforcing bars 14 are embedded in the PC slab 11, and the action parts of the dowel reinforcing bars 14 protrude upward from the upper surface of the PC slab 11. end face has a rough surface finish. The PC slab 11 has both ends placed on the horizontal surfaces 4 of the corbels 3, and both end surfaces face the vertical surfaces 5 of the joints at an interval of, for example, 50 to 150 mm, with the protruding portions 13 fitting within the same interval. When placed, the anchoring rebars 8 protrude above the PC slab 11 through through holes formed in the PC slab 11.

[0027] (Cast-in-place concrete 15) The cast-in-place concrete 15 is not only in contact with the top surface of the PC slab 11, but is also poured around and formed between the vertical surface 5 and the end surface of the PC slab 11. The thickness of the top slab is 500 to 2500 mm, of which the thickness of the PC slab 11 is 100 to 500 mm and the thickness of the cast-in-place concrete 15 is 400 to 2000 mm.

[0028] The cast-in-place concrete 15 is firmly bonded and integrated with the PC slab 11 by embedding the main parts of the dowel reinforcing bars 14 above the PC slab 11, embedding the protruding parts 13 of the PC steel 12 on the end face side of the PC slab 11 that has wrapped around and attaching thereto, and further biting into the rough-finished top and end faces of the PC slab 11.

[0029] The cast-in-place concrete 15 is firmly joined and integrated with the precast sidewall members 2 by burying and attaching the anchor rebars 8 and the enlarged diameter portions 9 and burying and attaching the continuous rebars 16 that are connected to and erected at the mechanical joints 6 of the two precast sidewall members 2 on the left and right.

[0030] The box culvert 1 of the embodiment configured as described above is transported to a construction site by the precast side wall member 2, the precast bottom slab member 10, and the PC slab 11, and assembled at the construction site as follows. It is well known that a plurality of box culverts are connected in the direction of the road length to form a waterway, road, etc.

[0031] (1) First, as shown in FIG. 2, a precast bottom slab member 10 is connected between the lower parts of two precast side wall members 2 on the left and right. (2) Next, as shown in Figures 3 and 4, the PC slab 11 is placed on the corbel 3 and erected. (3) Next, as shown in Figs. 5 to 7, the continuous reinforcing bars 16 are connected to the mechanical joints 6. At this time, the PC slabs 11 can be used as a work scaffold. (4) Next, as shown in Figures 8 and 9, cast-in-place concrete 15 is poured on top of the PC slab 11. At this time, the PC slab 11 functions as part of the formwork and is supported by the corbels 3, so no formwork support is required.

[0032] According to this embodiment, the following effects can be obtained. The PC steel 12 is involved in the adhesion of the cast-in-place concrete 15 at the end face side of the PC slab 11, thereby achieving strong integration between the PC slab 11 and the cast-in-place concrete 15. The anchoring rebar 8 prevents the PC slab 11 from coming loose or coming off before pouring, and after pouring, it can be firmly integrated with the cast-in-place concrete 15. The roughened top and end surfaces of the PC slab 11 improve adhesion to the cast-in-place concrete 15. -Since there are no lap joints at the joints, the quality is stable and it complies with the Japan Road Association's "Specifications for Road Bridges." - Complicated reinforcement for lap joints is no longer necessary, improving workability and worker safety. The reduction in on-site work will reduce noise and vibration, and formwork waste will also reduce the burden on the environment. -By using cast-in-place concrete15 and PC slabs11 that can introduce prestress enough to resist the load of the earth, it is possible to secure a longer span than with RC members, and it is also possible to expand the width standard of the culvert. In addition, the members have the ability to recover from cracks, making it a highly durable structure.

[0033] [Example 2] Example 2 shown in Fig. 10 differs from Example 1 in that a large double box culvert 21 is constructed by adding a precast intermediate wall member 22 having haunches on both sides, and the rest is common to Example 1. Example 2 also provides the same effects as Example 1.

[0034] The present invention is not limited to the above-described embodiment, and can be embodied by making appropriate modifications without departing from the spirit of the invention. [Explanation of symbols]

[0035] 1. Box culvert 2 Precast sidewall members 3. Hunch 4. Side 5 Vertical surface 6 Mechanical couplings 7 Reinforcing steel bars 8 Anchorage rebar 9 Expanded diameter part 10 Precast base plate members 11 PC version 12 PC steel material 13. Protruding Part 14 Dowel reinforcing bars 15 Cast-in-place concrete 16 Continuous reinforcing bars 21 Box culvert 22 Precast intermediate wall members

Claims

1. A PC plate (11) in which PC steel (12) is embedded; A concrete structure including cast-in-place concrete (15) formed in contact with the upper surface of the PC slab (11), The PC plate (11) has prestress applied to its lower edge by a pretensioning method, the top surface and end surfaces of the PC plate (11) are rough-finished, and the protruding portion (13) of the PC steel material (12) protruding from the end surface of the PC plate (11) is embedded in cast-in-place concrete (15) that has wrapped around the end surface side of the PC plate (11). A concrete structure characterized in that cast-in-place concrete (15) is embedded into the rough-finished top and end surfaces of the PC slab (11).

2. A precast member (2) having an L-shaped horizontal surface (4) and a vertical surface (5); A PC plate (11) in which a PC steel material (12) is embedded, the end of the PC plate (11) being placed on the horizontal surface (4) and the end face of the PC plate (11) facing the vertical surface (5); A concrete structure including cast-in-place concrete (15) formed in contact with the upper surface of the PC slab (11), A protruding portion (13) of the PC steel (12) protruding from an end face of the PC plate (11) is embedded in cast-in-place concrete (15) that has wrapped around between the vertical surface (5) and the end face of the PC plate (11), A concrete structure characterized in that a reinforcing bar (8) protruding from a side surface (4) of a precast member (2) protrudes above the PC plate (11) through a through hole formed in the PC plate (11) and is embedded in cast-in-place concrete (15).

3. 3. A concrete structure according to claim 2, wherein the reinforcing bars (16) protruding from the vertical faces (5) of the precast members (2) are embedded in the cast-in-place concrete (15).

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