JP2023079788A - Local structure of reinforcement concrete member and construction method of local structure of reinforcement concrete member - Google Patents

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

The present invention relates to a local structure of an axially stretched reinforced concrete member and a construction method thereof.

Reinforced concrete members such as piers and columns in structures such as bridges and viaducts are structured to absorb energy during earthquakes by locally plasticizing the ends of the members and forming plastic hinges during large-scale earthquakes. is common (see Non-Patent Document 1).

Here, in the seismic design of railway structures and road structures, the deformation performance is evaluated in consideration of the deformation of the skeleton and the deformation of the plastic hinge region during an earthquake. Therefore, by suppressing the deformation of the plastic hinge region and improving the toughness, it is possible to improve the deformation performance during an earthquake.

Therefore, in general, by increasing the amount of shear reinforcing reinforcing bars such as ties and intermediate ties, buckling of the axial reinforcing bars (main reinforcing bars) is prevented and deformation of the plastic hinge region is suppressed. is done.

In addition, Patent Document 1 discloses a concrete member that increases the toughness of the plastic hinge region and makes it less likely that damage will occur in regions other than the plastic hinge region by arranging spiral bars inside a reinforced concrete column. It is

Furthermore, in Patent Document 2, a pillar is constructed by a core member constructed at the center of the pillar using fiber-reinforced concrete and an outer shell member made of highly fluid concrete covering the core member. By doing so, it is disclosed that a concrete member that is less prone to construction defects can be made while ensuring shear strength.

Japanese Patent Application Laid-Open No. 2003-247297 JP 2020-159069 A

Hoshikuma et al., Experimental Study on Improvement of Seismic Performance of RC Bridge Piers Based on Arrangement of Axial Reinforcing Bars, Journal of Japan Society of Civil Engineers No.745/I-65, pp.1-14, 2003.10

However, if a large amount of shear reinforcing bars such as tie bars are placed in the plastic hinge region, the bar arrangement work becomes complicated, and factors such as concrete driving work that lower the workability increase.

Moreover, the reinforcement by the spiral reinforcement as in Patent Literature 1 may have an indirect and limited effect of restricting the core concrete. Furthermore, in the concrete member of Patent Document 2, fiber-reinforced concrete is placed on site, but fiber-reinforced concrete has a large pumping resistance and is difficult to construct efficiently. In addition, if the outer shell member in which the main reinforcing bars, the shear reinforcing bars, etc. are embedded is precast, the manufacturing cost will increase.

Therefore, the present invention is a local reinforced concrete member that can suppress deformation and improve toughness of a plastic hinge region provided locally, and can suppress an increase in the amount of reinforcing steel for shear reinforcement and improve workability. The purpose is to provide a general structure and its construction method.

In order to achieve the above object, a local structure of a reinforced concrete member of the present invention is a local structure of a reinforced concrete member that extends in the axial direction, and in a cross section that is substantially orthogonal to the axial direction, main rebars spaced in said cross-section facing towards; core members made of high-strength concrete and arranged in areas where compression in said cross-section occurs; and around said main rebars and said core members and concrete to be filled in.

Here, it is preferable that the range in which the compression in the cross section occurs is the range set by the equivalent stress block height a when calculating the bending strength. Moreover, it is preferable that the core material is arranged in a plastic hinge region in the axial direction of the reinforced concrete member. Further, the core material may be arranged continuously in the axial range of one or more times the height D of the cross section substantially perpendicular to the axial direction.

Moreover, it is preferable that a plurality of the core members be arranged in the cross section, and that the intervals between the adjacent core members be equal to or larger than the maximum aggregate diameter of the concrete. Furthermore, the core material may be arranged between the adjacent main reinforcing bars.

Further, the invention of a method for constructing a local structure of a reinforced concrete member is the method for constructing a local structure of a reinforced concrete member according to any one of the above, wherein the main reinforcing bars protrude in the axial direction to form a base surface. arranging the core material at a predetermined position on the base surface; and filling concrete around the main reinforcing bars and the core material.

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 of the reinforced concrete member stretched in the axial direction in the direction orthogonal to the axis. be done.

If the core material is arranged in the plastic hinge region locally provided in the reinforced concrete member, the deformation of the region can be suppressed and the toughness can be improved. In addition, since it is not necessary to increase the amount of reinforcing steel for shear reinforcement, workability can be improved.

In addition, the method for constructing a local structure of a reinforced concrete member is the same as the method for constructing a normal reinforced concrete member except for arranging the core material.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which illustrates typically the structure of the local structure of the reinforced concrete member of this Embodiment, Comprising: (a) is a horizontal cross-sectional view, (b) is a longitudinal cross-sectional view. It is explanatory drawing which showed typically the cross-sectional calculation of a reinforced concrete member. FIG. 10 is a diagram illustrating the value of the equivalent stress block height a, in which (a) is a graph when the standard of the main rebar is SD345, (b) is a graph when the standard of the main rebar is SD390, and (c) is It is a graph in case the standard of a main reinforcing bar is SD490. 4 is a graph illustrating values of equivalent stress block height a' determined based on past experimental data; FIG. 2 is an explanatory diagram showing types and characteristics of high-strength concrete; It is a graph of the experimental result which confirmed the deformation|transformation performance of the local structure of the reinforced concrete member of this Embodiment. It is explanatory drawing of the bridge in which the local structure of the reinforced concrete member of this Embodiment is provided. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which illustrates the cross section of the local structure of the reinforced concrete member of this Embodiment, (a) is explanatory drawing which showed the cross-sectional example 1 of a pier, (b) is explanatory drawing which showed the cross-sectional example 2 of a pier. is. FIG. 4 is a diagram illustrating a cross-section of a local structure of a reinforced concrete member according to the present embodiment, where (a) is an explanatory view showing cross-sectional example 3 of a pier, and (b) is an explanatory view showing cross-sectional example 4 of a pier. is. FIG. 2 is an explanatory diagram of a viaduct provided with a local structure of reinforced concrete members according to the present embodiment; FIG. 10 is a diagram illustrating a cross section of a local structure of a reinforced concrete member of the present embodiment, where (a) is an explanatory view showing Example 5 of the cross section of the column, and (b) is an explanatory view showing Example 6 of the cross section of the column; is. FIG. 10 is a diagram illustrating a cross section of a local structure of a reinforced concrete member according to the present embodiment, where (a) is an explanatory diagram showing Example 7 of the cross section of the column, and (b) is an explanatory diagram showing Example 8 of the cross section of the column; is. FIG. 11 is an explanatory diagram illustrating a method for constructing a local structure of a reinforced concrete member according to the present embodiment, using Example 7 of the cross section of a column; FIG. 11 is an explanatory diagram illustrating a construction method of a local structure of a reinforced concrete member according to the present embodiment, using Example 8 of the cross section of a column;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically illustrating the configuration of the local structure of a reinforced concrete member according to this embodiment.

The reinforced concrete members described in the present embodiment correspond to elongated columns, beams, bridge piers, plate-shaped members, and the like, which are extended in the axial direction. Such a reinforced concrete member has a range in which compression occurs within a cross section substantially orthogonal to the axial direction.

In this embodiment, first, the configuration will be described by taking as an example a bridge pier 1 that is a reinforced concrete member. FIG. 1(a) shows a cross-sectional view of a bridge pier 1 of this embodiment, and FIG. 2(b) shows a vertical cross-sectional view of the bridge pier 1. As shown in FIG.

In this embodiment, the bridge pier 1 is provided with a plastic hinge region 11 that plasticizes the local end portion of the pier 1 in order to absorb seismic energy in the event of a large-scale earthquake. do. FIG. 1(b) shows the plastic hinge area 11 of the pier 1 provided on the footing 12. FIG.

The cross-sectional structure of the plastic hinge region 11 of the bridge pier 1 of the present embodiment (the cross-sectional structure in the direction perpendicular to the axis) is, as shown in FIG. It is provided with main reinforcing bars 2 placed side by side, core materials 3 to be described later, and concrete 4 filled around the main reinforcing bars 2 and the core materials 3 .

The main reinforcing bars 2 are arranged at intervals along the edges in the cross section of the pier 1 which is substantially rectangular in plan view. The schematic diagram of FIG. 1( a ) shows an example in which one stage of main reinforcing bars 2 are arranged so as to surround the inner circumference of the pier 1 , but the present invention is not limited to this. It may be a cross section of the pier 1 on which the reinforcing bars 2 are arranged.

A band reinforcing bar 21 serving as a shear reinforcing reinforcing bar is arranged so as to surround the outer side of the main reinforcing bar 2 . In addition, an intermediate strap reinforcing bar 22 serving as a shear reinforcing reinforcing bar is bridged so as to partition the inner space of the strap reinforcing bar 21 which is substantially rectangular in plan view.

As shown in FIG. 1(b), a plurality of reinforcing bars 21 are arranged at intervals in the vertical direction. Intermediate reinforcing bars 22 are also arranged on each stage of the reinforcing bars 21 . Here, the plastic hinge region 11 of the pier 1 is set to a height equal to or greater than the cross-sectional height D, which is the height of the cross section.

The extent to which the plastic hinge region 11 is equal to or greater than the cross-sectional height D varies depending on the standard design guideline. For example, in the seismic design of road structures, h is set to 0.15h or less (1D if less than 1D), where h is the position where inertia force acts from the base of the pier (upper surface of footing 12). On the other hand, seismic design of railway structures shall be 2D or less.

Then, in the cross section of the pier 1 (Fig. 1(a)), one or more core members 3 are placed in the range where compression occurs between the main reinforcing bars 2 and in the cross section surrounded by the main reinforcing bars 2. placed. Therefore, the range in which compression occurs within the cross section will be described with reference to FIG.

FIG. 2 is a general explanatory diagram for explaining cross-sectional calculation of a reinforced concrete member using a schematic diagram. FIG. 2(a) shows a rectangular cross-section of a single-bar reinforced concrete member. Here, d is the effective height of the reinforced concrete section, b is the section width, and A _s is the section area of the tension reinforcing bar.

FIG. 2(b) shows a strain distribution occurring in a cross section when a beam-shaped reinforced concrete member is subjected to bending in which the lower side is in tension and the upper side is in compression. FIG. 3(c) shows the range of the equivalent stress block height a when calculating the bending strength. The range of this equivalent stress block height a is the range where compression within the cross section occurs.

a=1.18( _fyd / _f'cd )pd
Here, p is the tensile reinforcing bar ratio and is calculated by A _s /bd. Also, f _yd is the design yield strength of the main rebar, and f' _cd is the design compressive strength of concrete.

FIG. 3 is a diagram illustrating values of the equivalent stress block height a. FIG. 3(a) is a graph when the standard of the main rebar is SD345, FIG. 3(b) is a graph when the standard of the main rebar is SD390, and FIG. 3(c) is a graph when the standard of the main rebar is SD490. It is a graph of the case. Each graph was created for concrete with three types of design compressive strength (f' _cd =24 N/mm ² , f' _cd =27 N/mm ² , f' _cd =30 N/mm ² ). there is

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

In the local structure of the bridge pier 1 of this embodiment, the core material 3 is arranged at a position equal to or greater than the range of the equivalent stress block height a and at a position avoiding cover and reinforcing bars that are required to be ensured as concrete members.

The core material 3 is made of high-strength concrete, and is manufactured in various plane shapes such as a columnar shape and a prismatic shape. In short, the core material 3 is formed to have a length approximately equal to the height of the plastic hinge region 11 so as to be arranged continuously with the plastic hinge region 11 locally provided on the pier 1 .

FIG. 5 is an explanatory diagram showing the types and characteristics of high-strength concrete that can be used for the core material 3. As shown in FIG. The core material 3 can be made from fiber reinforced cementitious composites (FRCC), including multiple fine cracked fiber reinforced cementitious composites (HPFRCC) and ultra-high strength fiber reinforced concrete (UFC). It can also be made of polymer concrete or high-strength concrete with a compressive strength of about 80 N/mm ² or higher. For example, the core material 3 is made using ultra-high strength fiber reinforced concrete (UFC).

The core member 3 is a precast member with no reinforcing bars arranged, and is manufactured at a factory or manufacturing yard other than the construction site of the bridge pier 1. - 特許庁Since the core material 3 is not provided with reinforcing bars, the high-strength concrete used is not required to have high fluidity. In short, even the poor flowability of fiber reinforced cement composites (FRCC) can be used.

As described above, the core material 3 is arranged within the range of the equivalent stress block height a in the cross section. Also, it can be arranged in a range other than this. FIG. 1(a) illustrates an arrangement in which a plurality of cylindrical core members 3 are arranged in the range of the equivalent stress block height a or in the range adjacent thereto.

Here, the deformation performance of the local structure of the reinforced concrete member of this embodiment will be described with reference to the experimental results of FIG. In the experiment for confirming the deformation performance, the case of "no core material" in which the core material 3 was not arranged and the case of "with core material" in which the core material 3 was arranged were compared.

In the case of "with core material", the experimental results of the test piece with the core material arranged in 25% of the area of the upper and lower equivalent stress block height a of the rectangular cross section, and the total area of 50%. showing. The design compressive strength of the core material is 78 N/mm ² , the design compressive strength of the surrounding concrete and concrete without core material is 34 N/mm ² , and the design yield strength of the main rebar is 345 N/mm ² . and

In the experiment, a cyclic loading test was performed to confirm the deformation performance by repeating loading and unloading. The horizontal axis is horizontal displacement (mm), the vertical axis is load (kN), and "with core material" is a solid line. , "no core material" indicates the experimental results with a dashed line. Comparing the solid line (with core material) and the dashed line (without core material) in this figure, it can be confirmed that toughness is improved in the case of "with core material".

This is thought to be due to the suppression of compressive deformation of the concrete portion due to the placement of the core material 3 when a large compressive force acts, thereby suppressing the buckling of the main reinforcing bars 2. I can say that it could be improved.

Next, an example of the local structure of the reinforced concrete member according to the present embodiment will be described.
FIG. 7 is an explanatory diagram of a bridge 10 provided with a local structure of reinforced concrete members according to the present embodiment.

This bridge 10 has a structure in which girders are bridged over bridge piers 1 and abutments 1A provided on footings 12 supported by piles. Then, the pier 1 and the abutment 1A are reinforced concrete members that extend in the axial direction, which is the vertical direction.

The abutment 1 and the abutment 1A are provided with a plastic hinge region 11 in a local portion adjacent to the footing 12, and the plastic hinge region 11 is the reinforced concrete member of the present embodiment on which the core member 3 is arranged. becomes the local structure of

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

Cross-sectional example 1 shows an example in which the core material 3 is arranged in the range of the effective height d excluding the fogging and in the range of the equivalent stress block height a. Specifically, a core material 3 having a larger cross section than the cross section of the main reinforcing bars 2 is arranged between the main reinforcing bars 2 , 2 .

In short, the core material 3 whose cross-sectional dimension is at least partly equal to or smaller than the distance between the main reinforcing bars 2 is arranged alternately with the main reinforcing bars 2 along the main reinforcing bars 2 arranged in a line on the tension side and compression side of the cross section. are doing. Here, the range of the cross section of the pier 1 that is on 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. A core material 3 is to be placed.

Moreover, the space between the core materials 3, 3 is set to be equal to or larger than the maximum aggregate diameter of the concrete 4. That is, since the concrete 4 is filled around the core material 3, a space is secured that allows even the largest aggregate to pass through.

Main rebars 2 protrude upward from the upper surface (base surface) of the footing 12 on which the base of the pier 1 is provided. Place material 3. Then, by filling concrete 4 around the main reinforcing bars 2 and the core material 3, the plastic hinge region 11 of the pier 1 is constructed.

On the other hand, FIG. 8(b) shows a cross-sectional example 2 in which a rectangular parallelepiped (square prism-shaped) core member 3A is arranged. The cross-sectional example 2 is the same as the cross-sectional example 1 except for the shape of the core material 3A.

Also shown in FIG. 9 are two further cross-sectional examples of the plastic hinge region 11 of the pier 1 . FIG. 9(a) shows a cross-sectional example 3 in which a columnar core material 3B having a small cross-section which is substantially oval in plan view and a columnar core material 3C having a large cross-section which is substantially oval in plan view are arranged.

In cross-sectional example 3, the main reinforcing bars 2 are arranged in three rows on each of the tension side and the compression side of the cross section. Columnar core members 3B with a small cross section are arranged alternately with the three rows of main reinforcing bars 2 . Furthermore, in cross-sectional example 3, a columnar core material 3C with a large cross-section is arranged on the central side of the cross-section from the three rows of main reinforcing bars 2 .

In short, the range of the equivalent stress block height a of the cross section example 3 is wider than that of the cross section example 1, and the core material 3C made of high-strength concrete is arranged even in the range where the main reinforcing bars 2 near the center of the cross section are not arranged. do. The cross-sectional shape of the core material 3C is set to be equal to or less than the interval between the intermediate belt reinforcing bars 22. As shown in FIG. In addition, since the other configuration and construction method are the same as those of the cross-sectional example 1, description thereof is omitted.

On the other hand, FIG. 9B shows a cross-sectional example 4 in which a core material 3D having a small cross section and a core material 3E having a large cross section are arranged in the shape of a quadrangular prism which is substantially rectangular in plan view. Since the cross-sectional example 4 is the same as the cross-sectional example 3 except for the shape of the core members 3D and 3E, the description of the other configuration and construction method is omitted.

FIG. 10 is an explanatory diagram of a viaduct 50 provided with a local structure of reinforced concrete members according to the present embodiment. This elevated bridge 50 is a rigid-frame bridge in which columns 5 and main girders 53 and foundation beams 54 are rigidly connected. Then, the column 5 becomes a reinforced concrete member that extends in the axial direction, which is the vertical direction. Further, the main girder 53 and the foundation beam 54 are reinforced concrete members extending in the horizontal axial direction.

The column 5 is provided with a plastic hinge region 51 at a lower end portion adjacent to the foundation beam 54 and an upper end portion adjacent to the main girder 53. It becomes a local structure of reinforced concrete members in the form of A core member can also be arranged in the plastic hinge region 52 of the main girder 53 and the foundation beam 54 to form a local structure of the reinforced concrete member of the present embodiment.

FIG. 11 shows two cross-sectional examples of the plastic hinge region 51 of the post 5 . FIG. 11(a) shows a cross-sectional example 5 in which a cylindrical core material 3 is arranged. Here, the cross section of the pier 1 is a square cross section with one side having a height D of the cross section.

Since external forces act on the column 5 from all directions of the four sides, the range in which the compression set by the equivalent stress block height a occurs occurs along all the sides. In short, the main reinforcing bars 2 and the core material 3 are arranged so as to surround the inner peripheral edge of the square cross section.

Cross-sectional example 5 shows an example in which the core material 3 is arranged in the entire range of the equivalent stress block height a along the four sides within the range of the effective height d excluding the cover. Specifically, a core material 3 having a larger cross section than the cross section of the main reinforcing bars 2 is arranged between the main reinforcing bars 2 , 2 . In addition, since the other configuration and construction method are the same as those of the cross-sectional example 1, description thereof is omitted.

On the other hand, FIG. 11(b) shows a cross-sectional example 6 in which a rectangular parallelepiped (square prism-shaped) core member 3A is arranged. Since the cross-sectional example 6 is the same as the cross-sectional example 5 except for the shape of the core member 3A, the description of the other configuration and construction method is omitted.

Also shown in FIG. 12 are two further cross-sectional examples of the plastic hinge region 51 of the post 5 . FIG. 12(a) shows a cross-sectional example 7 in which a columnar core member 3 having a small cross-section which is substantially circular in plan view and a columnar core member 3F having a large cross-section which is also substantially circular in plan view are arranged.

In cross-sectional example 7, the main reinforcing bars 2 are arranged along the four sides of the square cross-section. Columnar core members 3 with a small cross section are arranged alternately with the main reinforcing bars 2 . Furthermore, in cross-sectional example 7, a columnar core material 3F with a large cross-section is arranged on the central side of the cross-section from the main reinforcing bar 2 .

In short, the range of the equivalent stress block height a of the cross section example 7 is wider than that of the cross section example 5, and the core material 3F made of high-strength concrete is arranged even in the range where the main reinforcing bars 2 near the center of the cross section are not arranged. do. The cross-sectional shape of the core material 3F is set to be equal to or less than the interval between the intermediate belt reinforcing bars 22. As shown in FIG. In addition, since the other configuration and construction method are the same as those of Example 5 of cross section, description thereof is omitted.

On the other hand, FIG. 12(b) shows a cross-sectional example 8 in which a core material 3A having a small cross section and a core material 3G having a large cross section are arranged in the shape of a quadrangular prism which is approximately square in plan view. Since the cross-sectional example 8 is the same as the cross-sectional example 7 except for the shapes of the core materials 3A and 3G, the description of the other configuration, construction method, and the like will be omitted.

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

In the first step, the foundation beams 54 (see FIG. 10) of the viaduct 50 are constructed so that the main reinforcing bars 2 protrude upward from the upper surface (base surface) of the foundation beams 54 (see FIG. 10). On the other hand, in the production yards of factories and sites, ultra-high-strength fiber reinforced concrete (UFC), which is high-strength concrete, is used to produce core materials 3, 3F (3A, 3G).

In the next step, the core material 3 (3A) is arranged along the row of the main reinforcing bars 2 between the main reinforcing bars 2 on the base surface, and fixed to the main reinforcing bars 2 with wire or the like. On the other hand, the large-section core material 3F (3G) surrounds the inner periphery of the square section at a predetermined position on the cross-sectional center side of the main reinforcing bar 2 with an interval equal to or larger than the maximum aggregate diameter of the concrete 4. placed like this. Here, when arranging the core members 3 and 3F (3A and 3G), they are installed at positions that do not interfere with the main reinforcing bars 2 and the intermediate belt reinforcing bars 22 .

Further, a holding member 6 is attached to the placed large-section core member 3F (3G). As the holding member 6, a frame member or the like having a substantially square shape in plan view can be used so as to pass through the plane center of the arranged core members 3F (3G). Then, the holding member 6 made of steel or the like and each of the core members 3F (3G) are joined together at joints 61 . By doing so, the plurality of core members 3F (3G) are integrated by the holding member 6, and can be prevented from moving from the position on the base surface where they are placed.

In the subsequent step, the plastic hinge region 51 of the column 5 is constructed by filling concrete 4 around the main reinforcing bars 2 and core materials 3, 3F (3A, 3G). At this time, the core material 3 (3A) with a small cross section is fixed to the main reinforcing bar 2 with wire or the like, and the core material 3F (3G) with a large cross section is connected and integrated with the holding material 6. , the filling pressure of the concrete 4 will not cause it to move from its predetermined position.

Next, the operation of the local structure of the reinforced concrete member and the construction method of the local structure of the reinforced concrete member according to the present embodiment will be described.
The local structure of the reinforced concrete member of the present embodiment configured in this manner is within the range where compression occurs in the cross section of the reinforced concrete member stretched in the axial direction in the direction perpendicular to the axis (the range of the equivalent stress block height a). , core members 3 (3A-3G) made of high-strength concrete are placed.

If the core material 3 (3A-3G) is arranged in the plastic hinge regions 11 and 51, which are local parts such as the bridge pier 1 and the column 5, the deformation of the region is suppressed and the toughness is improved. can be improved. That is, when a large compressive force is applied, the arrangement of the core members 3 (3A-3G) prevents the plastic hinge regions 11 and 51 from being crushed, thereby suppressing deformation. Furthermore, since buckling of the main reinforcing bars 2 is also suppressed, toughness can be improved.

In addition, since it is not necessary to increase the amount of reinforcing bars such as the shear reinforcing bars (21, 22), it is possible to improve workability without overly dense bar arrangement. In particular, when the deformation is suppressed by increasing the amount of reinforcing bars, there is a possibility that the fracture of the axial reinforcing bars will cause a rapid decrease in yield strength. , can reduce such risks. Furthermore, if the core material 3 (3A-3G) is made of high-strength concrete without reinforcement, it can be manufactured easily and inexpensively.

In addition, in the construction method of the local structure of the reinforced concrete member of the present embodiment, except for arranging the core material 3 (3A-3G), since it is the same as the construction method of the normal reinforced concrete member, it is easy and does not require skill. can be constructed in

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment. Included in the invention.

For example, in the above embodiment, the local structures of the piers 1 and columns 5 have been described in detail, but the present invention is not limited to this. The present invention can also be applied to local structures that serve as hinges.

1: Bridge pier (concrete member)
1A: 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 (7)

A local structure of an axially stretched reinforced concrete member, comprising:
In a cross section substantially perpendicular to the axial direction,
main rebars spaced in the cross section in the axial direction;
a core material made of high-strength concrete and positioned in an area where compression within said cross-section occurs;
A local structure of a reinforced concrete member, comprising concrete filled around the main reinforcing bars and the core material. 2. The local structure of a reinforced concrete member according to claim 1, wherein the range in which the compression within the cross section occurs is a range set by the equivalent stress block height a when calculating the bending strength. 3. Local structure of reinforced concrete member according to claim 1 or 2, characterized in that the core material is arranged in the plastic hinge region in the axial direction of the reinforced concrete member. 4. The reinforced concrete member according to claim 3, wherein the core material is continuously arranged in a range in the axial direction that is equal to or greater than a height D of the cross section substantially perpendicular to the axial direction. structure. A plurality of said core materials are arranged in said cross section, and said core materials are arranged so that the distance between adjacent said core materials is equal to or larger than the maximum aggregate diameter of said concrete. Item 5. A local structure of the reinforced concrete member according to any one of Items 1 to 4. 6. Local structure of reinforced concrete member according to any one of claims 1 to 5, characterized in that said core material is arranged between said adjacent main reinforcing bars. A method for constructing a local structure of a reinforced concrete member according to any one of claims 1 to 6,
forming a base surface from which the main reinforcing bars protrude in the axial direction;
disposing the core material at a predetermined position on the base surface;
and filling concrete around the main reinforcing bars and the core material.

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