Local structure of reinforced concrete members and method for constructing local structure of reinforced concrete members

Abstract

To provide local structure of reinforcement concrete members that can restrain deformation of a plastic hinge region locally provided and improve toughness, and can improve workability by suppressing an increase of a reinforcement amount of shearing strengthening reinforcement.SOLUTION: The present invention relates to local structure of reinforcement concrete members extending to an axial direction. The local structure of the reinforcement concrete members comprises main reinforcements 2 arranged spaced apart within a cross section towards the axial direction in the cross section substantially orthogonal to the axial direction, core materials 3 made with high strength concrete and arranged in the region where compression is taken place within the cross section, and concrete 4 that is filled around the main reinforcements and the core material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a local structure for a reinforced concrete member that is extended in the axial direction, and a method for constructing the same. [Background technology]

[0002] In structures such as bridges and elevated bridges, reinforced concrete members such as bridge piers and columns are generally designed to absorb seismic energy by locally plasticizing the ends of the members during large-scale earthquakes, thereby forming plastic hinges (see Non-Patent Document 1).

[0003] In the seismic design of railway and road structures, deformation performance is evaluated by considering the deformation of the main body and the deformation of the plastic hinge region during an earthquake. Therefore, it is believed that improving ductility by suppressing the deformation of the plastic hinge region can improve deformation performance during earthquakes.

[0004] Therefore, generally, the amount of shear reinforcement bars, such as stirrups and intermediate stirrups, is increased to prevent buckling of the axial reinforcement (main reinforcement) and suppress deformation in the plastic hinge region.

[0005] Furthermore, Patent Document 1 discloses a concrete member in which spiral reinforcement is placed inside a reinforced concrete column to increase the toughness of the plastic hinge region and to reduce the likelihood of failure in regions other than the plastic hinge region.

[0006] Furthermore, Patent Document 2 discloses that by constructing a column with a core member built in the center of the column using fiber-reinforced concrete and an outer shell member made of highly fluid concrete covering the core member, it is possible to create a concrete member that is less prone to construction defects while ensuring shear strength. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2003-247297 [Patent Document 2] Japanese Patent Publication No. 2020-159069 [Non-patent literature]

[0008] [Non-Patent Document 1] Hoshikuma et al., Experimental study on improving the seismic performance of reinforced concrete bridge piers based on the arrangement method of axial reinforcement bars, Journal of Japan Society of Civil Engineers, No. 745 / I-65, pp. 1-14, 2003.10 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, if a large amount of shear reinforcement, such as stirrups, is placed in the plastic hinge region, the reinforcement work becomes more complex, and factors that reduce constructability, such as concrete pouring, increase.

[0010] Furthermore, reinforcement using spiral reinforcement, as described in Patent Document 1, may result in an indirect and limited restraining effect on the core concrete. Moreover, the concrete member described in Patent Document 2 involves pouring fiber-reinforced concrete on-site, but fiber-reinforced concrete has high pumping resistance, making efficient construction difficult. In addition, if the outer shell member with embedded main reinforcement and shear reinforcement is precast, the manufacturing cost will increase.

[0011] Therefore, the present invention aims to provide a local structure for a reinforced concrete member and a method for constructing the same, which can suppress deformation and improve toughness in a locally provided plastic hinge region, while also improving workability by suppressing an increase in the amount of shear reinforcement bars. [Means for solving the problem]

[0012] In order to achieve the above object, the local structure of the reinforced concrete member of the present invention is a local structure of a reinforced concrete member extending in the axial direction. In a cross section substantially orthogonal to the axial direction, main reinforcing bars are arranged at intervals in the cross section in the axial direction, a core material made of high-strength concrete and arranged in a range where compression occurs in the cross section, and concrete filled around the main reinforcing bars and the core material. It is characterized by comprising the above.

[0013] Here, the range where compression occurs in the cross section is preferably a range set by the equivalent stress block height a at the time of calculating the flexural strength. Further, the core material is preferably arranged in the plastic hinge region in the axial direction of the reinforced concrete member. Furthermore, the core material can be configured to be continuously arranged in a range in the axial direction that is 1 time or more the height D of the cross section substantially orthogonal to the axial direction.

[0014] Also, the core material is one in which a plurality are arranged in the cross section, and it is preferable that the interval between adjacent core materials is set to be equal to or greater than the maximum aggregate diameter of the concrete. Furthermore, the core material can be configured to be arranged between adjacent main reinforcing bars.

[0015] Also, the invention of the construction method of the local structure of the reinforced concrete member is the construction method of the local structure of the reinforced concrete member described in any of the above, and includes a step of forming a base surface in which the main reinforcing bars project in the axial direction, a step of arranging the core material at a predetermined position on the base surface, and a step of filling concrete around the main reinforcing bars and the core material. It is characterized by comprising the above.

Effect of the Invention

[0016] In the local structure of the reinforced concrete member of the present invention configured as described above, a core material made of high-strength concrete is arranged in a range where compression occurs in a cross section orthogonal to the axis of the reinforced concrete member extending in the axial direction.

[0017] If this core material is arranged in the plastic hinge region provided locally in the reinforced concrete member, the deformation of that region can be suppressed and the ductility can be improved. Also, since there is no need to increase the amount of reinforcing bars for shear reinforcement, the workability can be improved.

[0018] And in the invention of the method for constructing the local structure of the reinforced concrete member, except for arranging the core material, it is the same as the method for constructing an ordinary reinforced concrete member, so it can be easily constructed without the need for skill.

Brief Description of the Drawings

[0019] [Figure 1] It is a diagram schematically explaining the configuration of the local structure of the reinforced concrete member of the present embodiment, where (a) is a cross-sectional view and (b) is a longitudinal sectional view. [Figure 2] It is an explanatory diagram schematically showing the cross-sectional calculation of the reinforced concrete member. [Figure 3] It is a diagram exemplifying the value of the equivalent stress block height a, where (a) is a graph when the standard of the main reinforcement is SD345, (b) is a graph when the standard of the main reinforcement is SD390, and (c) is a graph when the standard of the main reinforcement is SD490. [Figure 4] It is a graph exemplifying the value of the equivalent stress block height a' obtained based on past experimental data. [Figure 5] It is an explanatory diagram showing the types and characteristics of high-strength concrete. [Figure 6] It is a graph of the experimental results confirming the deformation performance of the local structure of the reinforced concrete member of the present embodiment. [Figure 7] It is an explanatory diagram of a bridge where the local structure of the reinforced concrete member of the present embodiment is provided. [Figure 8] It is a diagram exemplifying the cross-section of the local structure of the reinforced concrete member of the present embodiment, where (a) is an explanatory diagram showing cross-section example 1 of the pier and (b) is an explanatory diagram showing cross-section example 2 of the pier. [Figure 9]This figure illustrates a cross-section of a local structure of a reinforced concrete member in this embodiment, where (a) is an explanatory diagram showing example cross-section of a bridge pier 3, and (b) is an explanatory diagram showing example cross-section of a bridge pier 4. [Figure 10] This is an explanatory diagram of an elevated bridge in which the local structure of the reinforced concrete member of this embodiment is provided. [Figure 11] This figure illustrates a cross-section of the local structure of a reinforced concrete member in this embodiment, where (a) is an explanatory diagram showing example cross-section of a column 5, and (b) is an explanatory diagram showing example cross-section of a column 6. [Figure 12] This figure illustrates a cross-section of the local structure of a reinforced concrete member in this embodiment, where (a) is an explanatory diagram showing example cross-section 7 of a column, and (b) is an explanatory diagram showing example cross-section 8 of a column. [Figure 13] This diagram illustrates the method for constructing the local structure of the reinforced concrete member in this embodiment, using a cross-sectional example of a column (7). [Figure 14] This diagram illustrates the method for constructing the local structure of the reinforced concrete member in this embodiment, using a cross-sectional example of a column (Example 8). [Modes for carrying out the invention]

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a schematic diagram illustrating the local structure of the reinforced concrete member in this embodiment.

[0021] The reinforced concrete members described in this embodiment include long columns, beams, bridge piers, and plate-shaped members that extend in the axial direction. In such reinforced concrete members, there is a region where compression occurs within a cross-section that is approximately perpendicular to the axial direction.

[0022] In this embodiment, we will first explain the structure using a reinforced concrete bridge pier 1 as an example. Figure 1(a) shows a cross-sectional view of the bridge pier 1 in this embodiment, and Figure 2(b) shows a longitudinal section of the bridge pier 1.

[0023] Furthermore, in this embodiment, we will describe a bridge pier 1 in which a plastic hinge region 11 is set, which is a local part of the bridge pier 1 that is plastically deformed at the end in order to absorb seismic energy during a large-scale earthquake. Figure 1(b) shows the plastic hinge region 11 of the bridge pier 1 provided on the footing 12.

[0024] The cross-sectional structure of the plastic hinge region 11 of the pier 1 in this embodiment (the cross-sectional structure perpendicular to the axis) is as shown in Figure 1(a), and comprises main reinforcing bars 2 arranged at intervals within the cross-section in the axial direction of the pier 1, a core material 3 (described later), and concrete 4 filled around the main reinforcing bars 2 and the core material 3.

[0025] The main reinforcement bars 2 are arranged at intervals along the edges of the cross-section of the pier 1, which is roughly rectangular in plan view. The schematic diagram in Figure 1(a) shows an example in which one row of main reinforcement bars 2 is arranged to surround the inner circumference of the pier 1, but it is not limited to this, and the cross-section of the pier 1 may have multiple rows of main reinforcement bars 2.

[0026] Stirrups 21, which serve as shear reinforcement, are placed around the outside of the main reinforcement bars 2. Intermediate stirrups 22, which also serve as shear reinforcement, are placed across the interior of the roughly rectangular stirrups 21 in plan view, dividing the space between them.

[0027] As shown in Figure 1(b), multiple stirrups 21 are arranged at intervals in the vertical direction. Intermediate stirrups 22 are also arranged in each row of stirrups 21. Here, the plastic hinge region 11 of the bridge pier 1 is set to a height of at least 1 times the cross-sectional height D, which is the height of the cross-section.

[0028] The extent to which the plastic hinge region 11 should be greater than or equal to 1x the cross-sectional height D varies depending on the design guidelines used as the standard. For example, in the seismic design of road structures, if the point of application of the inertial force from the base of the bridge pier (upper surface of the footing 12) is h, it is set to 0.15h or less (or 1D if it is less than 1D). On the other hand, in the seismic design of railway structures, it is set to 2D or less.

[0029] Then, within the cross-section of the pier 1 (Fig. 1(a)), one or more core materials 3 are arranged in the range where compression occurs between the main reinforcing bars 2, 2 or within the cross-section surrounded by the main reinforcing bars 2. Therefore, the range where compression occurs within the cross-section will be described while referring to Fig. 2.

[0030] Fig. 2 is a general explanatory diagram for explaining the cross-section calculation of a reinforced concrete member using a schematic diagram. Fig. 2(a) shows a rectangular cross-section of a single-reinforcement reinforced concrete member. Here, d is the effective height of the reinforced concrete cross-section, b is the cross-section width, and A s represents the cross-sectional area of the tensile reinforcement.

[0031] Fig. 2(b) shows the strain distribution generated within the cross-section when a bending moment that causes tension on the lower side and compression on the upper side acts on a beam-shaped reinforced concrete member. And Fig. 3(c) shows the range of the equivalent stress block height a during the calculation of the bending strength. This range of the equivalent stress block height a is the range where compression occurs within the cross-section.

[0032] a = 1.18(f yd / f’ cd )pd Here, p is the tensile reinforcement ratio and is calculated by A s / bd. Also, f yd is the design yield strength of the main reinforcement, and f’ cd represents the design compressive strength of the concrete.

[0033] Fig. 3 is a diagram illustrating the value of the equivalent stress block height a. Fig. 3(a) is a graph when the standard of the main reinforcement is SD345, Fig. 3(b) is a graph when the standard of the main reinforcement is SD390, and Fig. 3(c) is a graph when the standard of the main reinforcement is SD490. Also, each graph is created for concretes with three types of design compressive strengths (f’ cd = 24 N / mm 2 , f’ cd = 27 N / mm 2 , f’ cd = 30 N / mm 2 ).

[0034] On the other hand, Figure 4 is a graph illustrating the values ​​of the equivalent stress block height a' determined based on previous experimental data. That is, the range of the equivalent stress block height a can also be set by a' = 0.136pd.

[0035] In the local structure of the bridge pier 1 of this embodiment, the core material 3 is positioned at a height greater than or equal to the equivalent stress block height a, and at a location that avoids the concrete cover and reinforcing bars that are required to be secured as concrete members.

[0036] The core material 3 is manufactured from high-strength concrete into various planar shapes, such as cylindrical or rectangular columns, in the form of columns or blocks. In short, the core material 3 is formed to a length approximately equal to the height of the plastic hinge region 11, so that it is positioned continuously with the plastic hinge region 11 which is locally provided on the bridge pier 1.

[0037] Figure 5 is an explanatory diagram showing the types and characteristics of high-strength concrete that can be used for core material 3. Core material 3 can be manufactured from fiber-reinforced cement composite materials (FRCC) including multiple microcrack type fiber-reinforced cement composite material (HPFRCC) and ultra-high-strength fiber-reinforced concrete (UFC). It also has a compressive strength of 80 N / mm². 2 It can also be manufactured using polymer concrete or high-strength concrete of a certain degree or higher. For example, core material 3 can be manufactured using ultra-high-strength fiber-reinforced concrete (UFC).

[0038] Core material 3 is a precast member without reinforcing bars and is manufactured at a factory or fabrication yard other than the site where pier 1 is constructed. Since core material 3 does not have reinforcing bars, high fluidity is not required for the high-strength concrete used. In short, it can be used even if the fiber-reinforced cement composite material (FRCC) has low fluidity.

[0039] As described above, the core material 3 is positioned within the equivalent stress block height a in the cross-section. It can also be positioned in other areas. Figure 1(a) illustrates an arrangement in which multiple cylindrical core materials 3 are lined up within or adjacent to the equivalent stress block height a.

[0040] Here, the deformation performance of the local structure of the reinforced concrete member of this embodiment will be explained with reference to the experimental results in Figure 6. In the experiment to confirm the deformation performance, a comparison was made between the case without core material 3 ("without core material") and the case with core material 3 ("with core material").

[0041] In the case of "with core material," the experimental results are shown for specimens in which the core material is placed over 25% of the area of ​​the equivalent stress block height a at the top and bottom of the rectangular cross-section, for a total area of ​​50%. The design compressive strength of the core material is 78 N / mm². 2 The design compressive strength of the surrounding concrete and the concrete without core material is 34 N / mm². 2 The design yield strength of the main reinforcement is 345 N / mm². 2 That's what I decided.

[0042] The experiment involved repeated loading and unloading to confirm deformation performance. The experimental results were shown on a graph with horizontal displacement (mm) on the horizontal axis and load (kN) on the vertical axis, with a solid line representing "with core material" and a dashed line representing "without core material". Comparing the solid line (with core material) and the dashed line (without core material) in this figure, it can be confirmed that the toughness is improved in the "with core material" case.

[0043] This suggests that when a large compressive force is applied, the presence of core material 3 suppresses the compressive deformation of the concrete portion, thereby preventing buckling of the main reinforcement bars 2 and improving ductility.

[0044] Next, an example of the local structure of the reinforced concrete member in this embodiment will be described. Figure 7 is an explanatory diagram of a bridge 10 in which the localized structure of the reinforced concrete member of this embodiment is provided.

[0045] This bridge 10 has a structure in which girders are stretched across piers 1 and abutments 1A, which are provided on footings 12 supported by piles. The piers 1 and abutments 1A are reinforced concrete members that extend in the axial direction, which is the vertical direction.

[0046] The pier 1 and abutment 1A are provided with a plastic hinge region 11 in a localized area adjacent to the footing 12, and this plastic hinge region 11 constitutes the local structure of the reinforced concrete member in this embodiment where the core material 3 is placed.

[0047] Figure 8 shows two cross-sectional examples of the plastic hinge region 11 of the bridge pier 1. Figure 8(a) shows cross-sectional example 1 with a cylindrical core material 3 in place. Here, the cross-section of the bridge pier 1 is a rectangular cross-section with a cross-sectional height D.

[0048] In Section Example 1, we show an example in which the core material 3 is placed within the range of the equivalent stress block height a, which is within the effective height d excluding the concrete cover. Specifically, the core material 3, which has a cross-section slightly larger than that of the main reinforcement bars 2, is placed between the main reinforcement bars 2,2.

[0049] In short, core material 3, whose cross-sectional dimensions in at least one part are less than or equal to the spacing between main reinforcement bars 2, is arranged alternately with the main reinforcement bars 2, which are arranged in a single row on the tension side and compression side of the cross-section. Here, the area of ​​the cross-section of the bridge pier 1 that becomes the compression side due to the action of an external force in one direction becomes the tension side due to the action of an external force in the opposite direction, so the main reinforcement bars 2 and core material 3 are arranged on both the tension side and the compression side of the cross-section.

[0050] Furthermore, the spacing between core materials 3,3 shall be greater than or equal to the maximum aggregate diameter of the concrete 4. In other words, since concrete 4 will be filled around the core material 3, sufficient space must be ensured so that even the largest aggregate can pass through.

[0051] Since the main reinforcing bars 2 protrude upward from the upper surface (base surface) of the footing 12 on which the base of the pier 1 is provided, the core material 3 is placed at a predetermined position on the base surface along the row of main reinforcing bars 2. Then, the plastic hinge region 11 of the pier 1 is constructed by filling the area around the main reinforcing bars 2 and the core material 3 with concrete 4.

[0052] On the other hand, Figure 8(b) shows a cross-sectional example 2 in which a rectangular (square prism-shaped) core material 3A is arranged. Cross-sectional example 2 is the same as cross-sectional example 1 except for the shape of the core material 3A, so the explanation of other components and construction methods will be omitted.

[0053] Figure 9 also shows two other cross-sectional examples of the plastic hinge region 11 of the bridge pier 1. Figure 9(a) shows cross-sectional example 3 in which a columnar core material 3B with a small cross-section that is roughly oval in plan view and a columnar core material 3C with a large cross-section that is also roughly oval in plan view are arranged.

[0054] In Section Example 3, three rows of main reinforcement bars 2 are arranged on both the tension and compression sides of the cross-section. Small-section columnar core materials 3B are then placed alternately with these three rows of main reinforcement bars 2. Furthermore, in Section Example 3, large-section columnar core materials 3C are placed closer to the center of the cross-section than the three rows of main reinforcement bars 2.

[0055] In short, the range of equivalent stress block height a in Section Example 3 is wider than in Section Example 1, and core material 3C made of high-strength concrete is placed even in the area where the main reinforcement bars 2 are not placed near the center of the cross section. The cross-sectional shape of this core material 3C is less than or equal to the spacing of the intermediate stirrups 22. Note that other components and construction methods are the same as in Section Example 1, so the explanation is omitted.

[0056] On the other hand, Figure 9(b) shows Section Example 4, in which a small-section core material 3D and a large-section core material 3E are arranged in a roughly rectangular, rectangular prism shape in plan view. Since Section Example 4 is the same as Section Example 3 except for the shapes of the core materials 3D and 3E, the explanation of other configurations and construction methods will be omitted.

[0057] Figure 10 is an explanatory diagram of an elevated bridge 50 in which the local structure of reinforced concrete members of this embodiment is provided. This elevated bridge 50 is a rigid frame bridge in which the columns 5 and the main girders 53 and foundation beams 54 are rigidly connected. The columns 5 are reinforced concrete members that extend in the axial direction, which is the vertical direction. The main girders 53 and foundation beams 54 are reinforced concrete members that extend in the axial direction, which is the horizontal direction.

[0058] This column 5 is provided with plastic hinge regions 51 at its lower end adjacent to the foundation beam 54 and at its upper end adjacent to the main girder 53. These plastic hinge regions 51 constitute the local structure of the reinforced concrete member in this embodiment, where the core material 3 is placed. Furthermore, core material can also be placed in the plastic hinge regions 52 of the main girder 53 and the foundation beam 54 to create local structures of the reinforced concrete member in this embodiment.

[0059] Figure 11 shows two cross-sectional examples of the plastic hinge region 51 of column 5. Figure 11(a) shows cross-sectional example 5 with a cylindrical core material 3 arranged. Here, the cross-section of the bridge pier 1 is a square cross-section with one side having a cross-sectional height D.

[0060] Since external forces act on column 5 from all four directions, the area where compression occurs, as defined by the equivalent stress block height a, occurs along all sides. In short, the main reinforcement bars 2 and core material 3 are arranged to surround the inner periphery of the square cross-section.

[0061] Sectional Example 5 shows an example in which core material 3 is placed in the entire range of the equivalent stress block height a along all four sides, within the effective height d excluding the concrete cover. In detail, core material 3, which has a cross-section slightly larger than that of the main reinforcement bars 2, is placed between the main reinforcement bars 2,2. Note that the other configurations and construction methods are the same as in Sectional Example 1, so the explanation is omitted.

[0062] On the other hand, Figure 11(b) shows a cross-sectional example 6 in which a rectangular (square prism-shaped) core material 3A is arranged. Cross-sectional example 6 is the same as cross-sectional example 5 except for the shape of the core material 3A, so the other configurations and construction methods will not be explained.

[0063] Figure 12 also shows two other cross-sectional examples of the plastic hinge region 51 of column 5. Figure 12(a) shows a cross-sectional example 7 in which a columnar core material 3 with a small cross-section that is roughly circular in plan view and a columnar core material 3F with a large cross-section that is also roughly circular in plan view are arranged.

[0064] In Section Example 7, main reinforcement bars 2 are arranged along each of the four sides of the square cross-section. Small-section columnar core members 3 are then placed alternately with the main reinforcement bars 2. Furthermore, in Section Example 7, large-section columnar core members 3F are placed closer to the center of the cross-section than the main reinforcement bars 2.

[0065] In short, the range of equivalent stress block height a in section example 7 is wider than in section example 5, and core material 3F made of high-strength concrete is placed even in the area where the main reinforcement bars 2 are not placed near the center of the section. The cross-sectional shape of this core material 3F is less than or equal to the spacing of the intermediate stirrups 22. Note that the other configurations and construction methods are the same as in section example 5, so the explanation is omitted.

[0066] On the other hand, Figure 12(b) shows Section Example 8, in which a small-section core material 3A and a large-section core material 3G are arranged in the shape of a rectangular prism with a roughly square cross-section in plan view. Since Section Example 8 is the same as Section Example 7 except for the shapes of the core materials 3A and 3G, the explanation of other configurations and construction methods will be omitted.

[0067] Next, the method for constructing the local structure of the reinforced concrete member in this embodiment will be explained with reference to Figures 13 and 14. Here, the cross-sectional structure shown in Figure 13 is the cross-sectional example 7 of Figure 12(a) described above, and the cross-sectional structure shown in Figure 14 is the cross-sectional example 8 of Figure 12(b) described above.

[0068] In the first step, the foundation beam 54 (see Figure 10) of the elevated bridge 50 is constructed so that the main reinforcing bars 2 protrude upward from the upper surface (base surface) of the foundation beam 54. Meanwhile, in the factory or on-site fabrication yard, the core materials 3, 3F (3A, 3G) are manufactured using ultra-high-strength fiber-reinforced concrete (UFC), which is a high-strength concrete.

[0069] In the next step, core material 3(3A) is placed between the main reinforcing bars 2,2 on the base surface, along the row of main reinforcing bars 2, and fixed to the main reinforcing bars 2 with binding wire or the like. Meanwhile, the large-section core material 3F(3G) is placed at a predetermined position on the center side of the cross-section, further towards the main reinforcing bars 2, with a spacing greater than or equal to the maximum aggregate diameter of the concrete 4, so as to surround the inner circumference of the square cross-section. When placing core material 3,3F(3A,3G), it is installed in a position that does not interfere with the main reinforcing bars 2 or the intermediate stirrups 22.

[0070] Furthermore, support members 6 are attached to the large-section core members 3F(3G) that have been placed. The support members 6 can be frame members or the like, which are formed in a roughly square shape in plan view so as to pass through the center of the plane of the arranged core members 3F(3G). Then, the support members 6, which are made of steel or the like, and each core member 3F(3G) are joined at the joint 61. In this way, multiple core members 3F(3G) are integrated by the support members 6, preventing them from moving from their position on the base surface where they are installed.

[0071] In the next step, concrete 4 is filled around the main reinforcement bars 2 and core materials 3, 3F (3A, 3G) to construct the plastic hinge region 51 of the column 5. At this time, the small-section core material 3 (3A) is fixed to the main reinforcement bars 2 with binding wire or the like, and the large-section core material 3F (3G) is connected and integrated with a holding material 6, so that it does not move from its predetermined position due to the filling pressure of the concrete 4.

[0072] Next, the operation of the local structure of the reinforced concrete member and the method for constructing the local structure of the reinforced concrete member in this embodiment will be described. In this embodiment, the local structure of the reinforced concrete member is such that core material 3 (3A-3G) made of high-strength concrete is placed in the area where compression occurs in the cross-section perpendicular to the axis of the axially extended reinforced concrete member (the area of ​​equivalent stress block height a).

[0073] If the core material 3 (3A-3G) is placed in localized areas such as bridge piers 1 and columns 5, which are plastic hinge regions 11 and 51, it can suppress deformation in those regions and improve toughness. In other words, when a large compressive force is applied, the presence of the core material 3 (3A-3G) prevents crushing of the plastic hinge regions 11 and 51, thereby suppressing deformation. Furthermore, buckling of the main reinforcement bars 2 is also suppressed, thus improving toughness.

[0074] Furthermore, since there is no need to increase the amount of reinforcing bars such as shear reinforcement bars (21, 22), the reinforcement is not densely packed, and workability can be improved. In particular, when deformation is suppressed by increasing the amount of reinforcing bars, there is a possibility that a sudden decrease in load-bearing capacity may occur due to the fracture of axial reinforcement bars, but with the localized structure of the reinforced concrete member of this embodiment, such a risk can be reduced. Moreover, if the core material 3 (3A-3G) is made of high-strength concrete without reinforcement bars, it can be manufactured easily and inexpensively.

[0075] Furthermore, in the method for constructing the local structure of the reinforced concrete member in this embodiment, the method is the same as the conventional method for constructing reinforced concrete members, except for the placement of the core material 3 (3A-3G), and therefore, it can be easily constructed without requiring skilled labor.

[0076] While embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and any design modifications that do not depart from the spirit of the present invention are included in the present invention.

[0077] For example, while the above embodiment described in detail the local structures of piers 1 and columns 5, the present invention is not limited to these, and can also be applied to local structures that act as plastic hinges for reinforced concrete members such as the deck slab, walls, and top slab of a box culvert. [Explanation of symbols]

[0078] 1: Bridge pier (concrete member) 1A: Bridge abutment (concrete member) 11: Plastic hinge region 2: Main reinforcing bars 3,3A-3G: Core material 4: Concrete 5: Column (concrete member) 51, 52: Plastic hinge region D: Section height a: Equivalent stress block height

Claims

1. A local structure of a reinforced concrete member that extends in the axial direction, Within the cross-section that is substantially perpendicular to the axial direction, Main reinforcing bars arranged at intervals within the cross-section in the axial direction, A core material made solely from high-strength concrete, positioned within the range set by the equivalent stress block height a during bending strength calculation, and arranged only along the edges of the cross-section, The system comprises the main reinforcing bars and concrete filled around the core material, The local structure of a reinforced concrete member is characterized in that the core material has a cross-sectional dimension less than or equal to the spacing between adjacent main reinforcing bars along the sides of the cross-section, and the core material and the main reinforcing bars are arranged alternately along the sides of the cross-section.

2. The local structure of a reinforced concrete member according to claim 1, characterized in that the core material is arranged in the plastic hinge region in the axial direction of the reinforced concrete member.

3. The local structure of a reinforced concrete member according to claim 2, characterized in that the core material is continuously arranged in the axial range which is at least one times the height D of the cross-section that is substantially perpendicular to the axial direction.

4. The local structure of a reinforced concrete member according to any one of claims 1 to 3, characterized in that a plurality of core materials are arranged within the cross-section, and the spacing between adjacent core materials is greater than or equal to the maximum aggregate diameter of the concrete.

5. A method for constructing a local structure of a reinforced concrete member according to any one of claims 1 to 4, The process of forming a base surface that protrudes in the axial direction of the main reinforcement, The steps include: arranging the core material between adjacent main reinforcing bars along the edge of the base surface; A method for constructing a localized structure of a reinforced concrete member, characterized by comprising the step of filling concrete around the main reinforcing bars and the core material.

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