Structures

Abstract

To provide a reinforcing bar concrete frame which is provided with a column, a short span beam, and a bearing wall, and in which it is possible to reduce a column width while ensuring yield strength and deformation performance.SOLUTION: A frame of reinforcing bar concrete comprises a pair of reinforcing bar concrete subsidiary columns 21, a reinforcing bar concrete boundary beam 22 which connects top parts of the subsidiary columns 21, and a reinforcing bar concrete earthquake-resisting wall 20 joined to the pair of subsidiary columns 21. A material axis length L3 of the boundary beam 22 is shorter than a width L2 of the earthquake-resisting wall 20. Concrete bodies 30, 40, 50 for the subsidiary column 21, the boundary beam 22, and the earthquake-resisting wall 20 are formed with steel fiber reinforcement concrete in which steel fibers are mixed in an amount of 0.3-2.0% with respect to the concrete volume. A width W1 of the subsidiary column 21 is identical to a wall thickness W2 of the earthquake-resisting wall 20.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a reinforced concrete frame structure and a structure including this reinforced concrete frame structure.

Background Art

[0002] Conventionally, the use of fiber-reinforced concrete for reinforced concrete columns has been proposed. For example, Patent Document 1 discloses a super high-rise building in which some of the reinforced concrete columns arranged on the outer periphery of the first floor above ground are formed of fiber-reinforced concrete. This fiber-reinforced concrete has a compressive strength of 80 N / mm 2 or higher ultra-high-strength concrete mixed with steel fibers having a fiber diameter of 0.1 to 1 mm and a fiber length of 60 mm or less.

[0003] In addition, it has been proposed to connect continuous seismic walls to each other with damper members. For example, Patent Document 2 discloses a vibration control frame structure in which two or more continuous seismic walls arranged at a certain interval are connected and integrated by a plurality of damper members. The damper member is configured as a boundary beam made of mild steel, or a boundary beam with a hysteretic or viscous damping device interposed in the middle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of Invention

Problems to be Solved by the Invention

[0005] The present invention provides a reinforced concrete frame structure including columns, short-span beams and load-bearing walls, which can reduce the column width while ensuring load-bearing capacity and deformation performance A structure equipped with The task is to provide such a structure. [Means for solving the problem]

[0006] The first reinforced concrete frame of the invention is a reinforced concrete frame comprising a pair of reinforced concrete columns (for example, ancillary columns 21 described later), a reinforced concrete beam (for example, a boundary beam 22 described later) connecting the tops of the columns, and a reinforced concrete shear wall (for example, a seismic wall 20 described later) joined to at least one of the pair of columns, wherein the axial length of the beam (for example, L3 described later) is shorter than the width of the shear wall (for example, L2 described later), the concrete bodies of the columns, beams, and shear walls are formed of fiber-reinforced concrete in which fibers are mixed in a ratio of 0.3% to 2.0% relative to the volume of concrete, and the width of the columns (for example, W1 described later) is 1.0 times or more but less than 2.0 times the wall thickness of the shear wall (for example, W2 described later).

[0007] According to this invention, columns, beams, and shear walls are formed from fiber-reinforced concrete in which fibers are mixed in an amount of 0.3% to 2.0% relative to the volume of the concrete. Therefore, the shear strength, and other load-bearing capacity and ductility (deformation performance) of the columns, beams, and shear walls can be significantly improved. As a result, the fibers provide reinforcement equivalent to or better than shear reinforcement bars, eliminating the need to densely reinforce shear walls and beams. Consequently, the width of the columns can be reduced to between 1.0 and 2.0 times the wall thickness of the shear wall, ensuring a user-friendly interior space while achieving shear walls with excellent load-bearing capacity and deformation performance. Furthermore, since the columns are formed from fiber-reinforced concrete, their deformation performance is improved, so even if the width of the columns is set to between 1.0 and 2.0 times the wall thickness of the shear wall, excellent deformation performance can be ensured. Furthermore, when designing the structure of a building, members constructed with fiber-reinforced concrete can be evaluated to have significantly greater shear strength, making it possible to reduce the size of the members and the amount of reinforcement compared to ordinary reinforced concrete members. In other words, the wall thickness of shear walls can be reduced, and the amount of shear reinforcement in beams can be reduced (or its strength reduced). In rigid frame structures with shear walls, the rigidity of the shear walls is greater than that of the rigid frame structure, so seismic forces concentrate on the shear walls, resulting in the problem of the shear walls becoming very thick. However, according to the present invention, the wall thickness of the shear walls can be reduced, thus suppressing the concentration of seismic forces on the shear walls. Therefore, it is possible to balance the rigidity and stress with the rigid frame structure surrounding the shear walls, and all members can be optimally designed against seismic forces.

[0008] The reinforced concrete frame of the second invention is characterized in that the width of the beam (for example, W3 described later) is 0.5 times or more the wall thickness of the load-bearing wall (for example, W2 described later).

[0009] According to this invention, the beam is formed from fiber-reinforced concrete in which fibers are mixed in at a concentration of 0.3% to 2.0% relative to the volume of the concrete. Therefore, since the fibers exert a reinforcing effect equivalent to or greater than that of shear reinforcement bars, the width of the beam can be made smaller, with a lower limit of 0.5 times or more the wall thickness of the load-bearing wall. This makes it possible to realize a beam with excellent load-bearing capacity and deformation performance while ensuring a user-friendly interior space.

[0010] The structure of the third invention (for example, buildings 1 and 1A described later) is a structure comprising the reinforced concrete frame described above, and further comprising a second column (for example, an ancillary column 21A described later) and a second shear wall (for example, an earthquake-resistant wall 20A described later) provided above or below the column and the shear wall, and a second beam (for example, a boundary beam 22A described later) connecting the tops of the second column, wherein the concrete bodies of the second column and the second shear wall are formed of concrete without fiber mixing, the main column reinforcement of the column (for example, the main column reinforcement 41 described later) is connected to the main column reinforcement of the second column via a reinforcement joint, and the vertical reinforcement of the shear wall (for example, the vertical reinforcement 31 described later) is connected to the vertical reinforcement of the second shear wall via a reinforcement joint.

[0011] Here, rebar splices refer to, for example, mechanical splices and lap splices. According to this invention, a second column and a second shear wall made of concrete without fibers are provided above or below a column and a shear wall made of fiber-reinforced concrete. Furthermore, the main reinforcement of the column is connected to the main reinforcement of the second column, and the vertical reinforcement of the shear wall is connected to the vertical reinforcement of the second shear wall. Therefore, a structure with excellent shear strength and deformation performance can be realized without forming all the columns and shear walls of the structure with fiber-reinforced concrete. [Effects of the Invention]

[0012] According to the present invention, a reinforced concrete frame including columns, short-span beams, and shear walls can reduce the column width while ensuring load-bearing capacity and deformation performance. A structure equipped with We can provide this. [Brief explanation of the drawing]

[0013] [Figure 1] This is a floor plan of a predetermined floor of a building to which a reinforced concrete frame structure according to the first embodiment of the present invention is applied. [Figure 2] This is a cross-sectional view of building AA in Figure 1. [Figure 3] This is a cross-sectional view of building BB in Figure 1. [Figure 4] These are an enlarged view and a plan view of a part of the building frame of Figure 3 (the portion enclosed by broken line C). [Figure 5] These are a front view, a transverse cross-sectional view, and a longitudinal cross-sectional view showing the structures of No. 1 to No. 3 test specimens used in the loading test. [Figure 6] This is an enlarged cross-sectional view of the wall portion and the column portion of the test specimen in Figure 5. [Figure 7] This is a diagram showing the test results of the loading test (the relationship between horizontal load Q and horizontal displacement δ). [Figure 8] This is a diagram showing the relationship between load and inter-story deformation angle for the examples and comparative examples. [Figure 9] This is a diagram showing the concrete volume and reinforcing bar weight for the examples and comparative examples. [Figure 10] This is a plan view of a building according to the second embodiment of the present invention. [Figure 11] This is a side view of the building in Figure 10. [Figure 12] This is a side view of a part of the building frame according to a modification of the present invention. [Modes for Carrying Out the Invention]

[0014] The present invention relates to a reinforced concrete building in which auxiliary columns and seismic walls arranged on the first and second floors of the building are formed of fiber-reinforced concrete, and boundary beams on each floor are also formed of fiber-reinforced concrete. Hereinafter, embodiments of the present invention will be described based on the drawings. In the following description of the embodiments, the same reference numerals are assigned to the same components, and the description thereof will be omitted or simplified. [First Embodiment] Figure 1 is a plan view of a predetermined floor of a building 1 as a structure to which a reinforced concrete frame according to the first embodiment of the present invention is applied. Figure 2 is an A-A cross-sectional view of the building 1 in Figure 1. Figure 3 is a B-B cross-sectional view of the building 1 in Figure 1.

[0015] Building 1 is a nine-story reinforced concrete building comprising multiple columns 2 extending vertically, multiple beams 3 connecting the tops of the multiple columns 2, and floors (not shown) supported by the multiple beams 3. Building 1 has a 3x3 span configuration in plan view, with the central part of Building 1 being the core section 4. The central span in the Y direction of Building 1 (core section 4) is equipped with non-opening shear walls 10 and 10A, while the spans at both ends in the Y direction of Building 1 are rigid frame structures made of columns and beams. On the other hand, the central span in the X direction of Building 1 (core section 4) is equipped with load-bearing walls and shear walls 20 and 20A as second load-bearing walls, columns and ancillary columns 21 and 21A as second columns, and boundary beams 22 and 22A as beams and second beams, while the spans at both ends in the X direction are rigid frame structures made of columns and beams.

[0016] The seismic walls 10, 10A, 20, and 20A are arranged continuously vertically to form a multi-story seismic wall. The seismic walls 10 and 20, the ancillary columns 21, and the boundary beams 22 are located on the first and second floors (1st and 2nd floors) of Building 1. In addition, the seismic walls 10A and 20A, the ancillary columns 21A, and the boundary beams 22A are located on the third floor and above of Building 1. The seismic walls 10, 20 and accompanying columns 21 located on the first and second floors are made of steel fiber-reinforced concrete mixed with steel fibers (shown by dashed lines in Figures 1 to 3). The seismic walls 10A, 20A and accompanying columns 21A located on the third floor and above are made of ordinary concrete without steel fibers. In addition, all boundary beams 22 and 22A are made of steel fiber-reinforced concrete mixed with steel fibers.

[0017] Figure 4(a) is an enlarged view of a portion of the building structure 1 in Figure 3 (the area enclosed by the dashed line C). Figure 4(b) is a plan view of a portion of the building structure 1 in Figure 4(a). As shown in Figures 4(a) and 4(b), the boundary beam 22 connects the tops of a pair of ancillary columns 21. The shear wall 20 is also joined to both of these ancillary columns 21. The seismic wall 20 comprises a concrete body 30 formed of steel fiber-reinforced concrete mixed with steel fibers, and vertical reinforcement bars 31 and horizontal reinforcement bars 32 embedded in the concrete body 30 and double-reinforced. The upper part of the seismic wall 20 is a wall beam 23 reinforced with beam main reinforcement bars 51, which will be described later. The auxiliary column 21 comprises a concrete body 40 formed of steel fiber-reinforced concrete mixed with steel fibers, a column main reinforcement 41 embedded in the concrete body 40 and extending vertically, and a hoop reinforcement 42 embedded in the concrete body 40 and wrapped around the column main reinforcement 41. The width W1 (column width) of the auxiliary column 21 is 1.0 times or more and less than 2.0 times the wall thickness W2 of the seismic wall 20. Here, the width W1 (column width) of the auxiliary column 21 is 1.0 times the wall thickness W2 of the seismic wall 20, and the auxiliary column 21 and the seismic wall 20 are flush.

[0018] The boundary beam 22 is a short-span beam comprising a concrete body 50 formed of steel fiber-reinforced concrete mixed with steel fibers, beam main reinforcement 51 embedded in the concrete body 50 and arranged in an X shape, and stirrups 52 wrapped around the beam main reinforcement 51. The axial length L3 of the boundary beam 22 is shorter than the width L2 of the shear wall 20. The width W3 of the boundary beam 22 is between 0.5 and 2.75 times the wall thickness W2 of the shear wall 20, with a lower limit of 0.5 times. Here, the width W3 of the boundary beam 22 is 1.0 times the wall thickness W2 of the shear wall 20, and the boundary beam 22 is flush with the shear wall 20.

[0019] The amount of steel fibers mixed into concrete bodies 30, 40, and 50 is between 0.3% and 2.0% of the concrete volume. These steel fibers have hooks at both ends, and the length of the steel fibers is between 0.1 mm and 0.6 mm. For steel fiber incorporation rates of 0.5% and 1.0% relative to the volume of concrete, the construction performance and structural performance were confirmed using the seismic wall test specimens shown in Table 1 and the boundary beams of the examples shown in Table 2. The upper limit of 2.0% for the steel fiber content relative to the concrete volume is based on the 2.0% steel fiber content used in ultra-high-strength fiber-reinforced concrete bridges (Japan Society of Civil Engineers: Design and Construction Guidelines (Draft) for Ultra-High-Strength Fiber-Reinforced Concrete, September 28, 2004, pp. 157-162). The lower limit of 0.3% for the steel fiber content relative to the concrete volume is based on the fact that a test specimen with a steel fiber content of 0.3% was created in a model test specimen of a steel fiber-reinforced concrete beam and its structural performance was confirmed (Toshihide Kimura et al.: Study on Shear Strength of RC Beams Shear-Reinforced with Steel Fibers and Stirrups, Annual Proceedings of the Concrete Engineering Society, Vol. 29, No. 3, 2007).

[0020] The seismic wall 20A and the ancillary column 21A have the same configuration as the seismic wall 20 and the ancillary column 21, but differ in that the concrete bodies 30 and 40 are made of ordinary concrete without steel fibers. The boundary beam 22A has the same configuration as the boundary beam 22. The vertical reinforcement bars 31 of the seismic wall 20 are connected to the vertical reinforcement bars 31 of the seismic wall 20A via reinforcement splices such as mechanical splices and lap splices. The main reinforcement bars 41 of the ancillary column 21 are connected to the main reinforcement bars 41 of the ancillary column 21A via reinforcement splices such as mechanical splices and lap splices.

[0021] [Force Test] Below, we fabricated four test specimens (No. 1 to No. 4) that mimicked the aforementioned seismic walls, and conducted loading tests by applying horizontal forces to verify the reinforcing effect of SFRC (reinforced concrete mixed with steel fibers). Figure 5 shows the front view, cross-sectional view, and longitudinal cross-sectional view of the structure of test specimens No. 1 to No. 3. Figure 6 is an enlarged view of the cross-section of the wall and column sections of the test specimens in Figure 5. Note that in test specimen No. 4, the amount of horizontal and vertical reinforcement in the wall section is twice that of test specimens No. 1 to No. 3 shown in Figures 5 and 6. The test specimens were designed to simulate the lower floors of a building, and were approximately 1 / 3 to 1 / 4 the size of the actual structure. Furthermore, each test specimen was constructed so that shear failure of the wall preceded bending yield at the base of the wall. Specifically, each test specimen had a wall thickness of 180 mm, an internal wall length of 1200 mm, a column width of the same as the wall thickness of 180 mm, and a column depth of 500 mm.

[0022] The composition of test specimens No. 1 to No. 4 is shown in Table 1 below. [Table 1]

[0023] As shown in Table 1, the concrete used to form the wall and column sections was ordinary concrete for specimen No. 1, and steel fiber reinforced concrete (SFRC) for specimens No. 2 to No. 4. The target strength of the concrete was 60 N / mm². 2 The amount of steel fiber added was 0.5% of the concrete volume for test specimens No. 2 and No. 4, and 1.0% of the concrete volume for test specimen No. 3. The steel fibers mixed into the concrete had a diameter of 0.55 mm, a length of 35 mm, an aspect ratio of 65, and a specific gravity of 7.85. These steel fibers were hooked by bending both ends.

[0024] For each test specimen, the main reinforcement of the columns was set to 12-D19 (SD490) with a reinforcement ratio of pg = 3.83% so that shear failure would occur first. The vertical and horizontal reinforcement in the wall sections was set to 2-D6@120(SD345) with a reinforcement ratio of ps=0.30% for specimens No.1 to No.3, and to 2-D6@60(SD345) with a reinforcement ratio of ps=0.59% for specimen No.4, with the aim of achieving equivalent shear strength between specimens No.3 and No.4.

[0025] For the above test specimens, a load-bearing device was used to maintain the axial force applied to the specimens, while displacement control points were installed on the upper stub of the specimens. Horizontal loads were repeatedly applied from both sides. The axial force ratio η of the column cross-section alone was set to 0.15. This axial force ratio η was calculated using the following formula. η = N / (2·Bc·Dc·σB) Here, N is the axial force (for two columns), Bc is the column width (= wall thickness 180 mm), Dc is the column depth (= 500 mm), and σB is the concrete compressive strength (N / mm²). 2 )

[0026] Figure 7 shows the results of the loading test (relationship between horizontal load Q and horizontal displacement δ). From Figure 7, the maximum horizontal load Q MAX It can be seen that specimen No. 2 is 1.11 times larger than specimen No. 1, specimen No. 3 is 1.18 times larger than specimen No. 1, and specimen No. 4 is 1.17 times larger than specimen No. 1. Furthermore, specimens No. 2 to No. 4, compared to specimen No. 1, were able to prevent a sharp decrease after the horizontal load Q reached its maximum, and the deformation performance was improved.Therefore, it can be seen that in ordinary concrete, when cracks occur, it is difficult to bear the tensile stress, so the cracks propagate widely, but in steel fiber reinforced concrete, when cracks occur, the steel fibers that form the crack bear the tensile stress, preventing the cracks from widening, and the crack width is smaller under the same load or deformation. Furthermore, Figure 7 shows that the load on specimen No. 3 decreased more slowly than that on specimen No. 4, indicating that even when the shear strength is equivalent, a higher steel fiber content results in improved deformation performance.

[0027] Therefore, as can be seen from Figure 7, a seismic wall formed with steel fiber-reinforced concrete in which the column width is the same as the wall thickness and 0.5% or 1.0% of steel fibers are mixed relative to the concrete volume exhibits smaller crack widths, improved critical deformation angle (ductility), and superior load-bearing capacity and deformation performance compared to a seismic wall formed with ordinary concrete that does not contain steel fibers. Furthermore, this loading test confirmed that the load-bearing capacity and deformation performance can be improved by mixing 0.5% or 1.0% steel fibers relative to the volume of concrete.

[0028] Therefore, by forming steel fiber-reinforced concrete shear walls with steel fiber-reinforced concrete that contains 0.3% to 2.0% steel fibers relative to the volume of concrete, the width of the columns and the thickness of the shear walls can be reduced. Specifically, it was confirmed that in steel fiber reinforced concrete shear walls, even when the column width is set to between 1.0 and 2.0 times the wall thickness of the shear wall, equivalent shear strength and deformation performance to that of reinforced concrete seismic walls can be obtained.

[0029] [Examples] The following simulation was conducted to verify the effects of constructing a building with steel fiber reinforced concrete. Example 1 is a building constructed from steel fiber reinforced concrete (SFRC) as described in the above embodiment, while the comparative example is a building constructed from reinforced concrete (RC) as described in the above embodiment. Specifically, the model building is a nine-story reinforced concrete structure with 8m spans in a 3x3 configuration. The building height is 31.2m, and the standard floor height is 3.4m (4.0m only on the first floor). The central core is an open space containing elevator shafts, and boundary beams and continuous shear walls are arranged in the X direction of the building, while continuous shear walls without openings are arranged in the Y direction. The floor slab will be 250 mm thick, and the floor load will be 1200 N / mm² as the finished load. 2 The load capacity is set to 1800 N / mm². 2 Furthermore, X-shaped reinforcement was adopted for the boundary beams. In addition, the ancillary columns were left without column shapes; that is, the width of the ancillary columns was made the same as the wall thickness of the shear wall.

[0030] The structural characteristics and simulation results of the buildings in the examples and comparative examples are shown in Table 2 below. [Table 2]

[0031] This simulation was performed using static incremental load analysis, a common method in structural design. Here, steel fiber reinforced concrete was represented by multiplying the shear strength of each member by 1.5. In reality, there would also be a reinforcing effect due to the high deformation performance (ductility), but this effect was not considered in this study. Qu represents the building's inherent horizontal load-bearing capacity. Qun represents the required load-bearing capacity for the building, which is the required horizontal load-bearing capacity. The structural characteristic coefficient Ds is a coefficient used to calculate the required horizontal load-bearing capacity of a building. It evaluates the energy absorption capacity associated with the building's elastoplastic behavior (damping, ductility, etc.), and the value of Ds decreases as the structure becomes more ductile.

[0032] Figures 8 and 9 show the simulation results. Figure 8 shows the relationship between the load in the Y direction (non-opening shear wall structure) and the inter-story drift angle for the example (SFRC model) and the comparative example (RC model). As shown in Figure 8, in the comparative example, the shear wall on the 8th floor underwent shear failure and exhibited brittle collapse behavior, while in the example, it exhibited overall collapse behavior. Figure 9 shows the concrete volume and rebar weight for the example (SFRC model) and the comparative example (RC model). As shown in Figure 9, it can be seen that the concrete volume can be reduced by approximately 12% and the rebar weight by approximately 20% in the example compared to the comparative example.

[0033] Furthermore, as confirmed by the results of the loading tests described above, the shear strength and ductility (deformation performance) of the members can be significantly improved in seismic walls and boundary beams (example, SFRC model) that incorporate steel fibers. Therefore, in the structural design of a building, when designing by verifying the margin of safety in the ultimate shear strength (guaranteed design), the structural member incorporating steel fibers according to the present invention (example, SFRC model) can be evaluated to have a much higher shear strength, making it possible to reduce the size of the member and the amount of reinforcement compared to ordinary reinforced concrete members. In other words, for shear walls, the wall thickness can be reduced, and for boundary beams with short spans, the amount of shear reinforcement can be reduced (or its strength can be reduced).

[0034] Furthermore, in the example (SFRC model), the wall thickness of the seismic wall cross-section (Y direction) is 200 mm to 350 mm, which is thinner than the wall thickness of the comparative example (RC model) which is 200 mm to 650 mm. As a result, as shown in Figure 8(a), the initial stiffness in the relationship between load and inter-story drift angle is gradual, and the deformation increases even after the point of maximum load is reached. In contrast, the comparative example (RC model) exhibited high initial stiffness in the relationship between load and inter-story drift angle, showing higher load-bearing capacity than the example. However, after shear failure occurred in the seismic wall on the 8th floor, it showed a brittle failure mode. In the comparative example (RC model), the maximum load-bearing capacity is determined by shear failure, while in the example (SFRC model), instead of a brittle failure mode, it exhibited a general collapse behavior in which the deformation performance did not rapidly decrease even after reaching the maximum load-bearing capacity.

[0035] As described above, the steel fiber concrete frame of the present invention (Example, SFRC model) allows for a thinner wall thickness of the shear walls compared to the comparative example (RC model), thereby suppressing the concentration of seismic force on the shear walls. Specifically, for each floor, the seismic force borne by the shear walls can be reduced to approximately 70% or less of the total seismic force. Therefore, it is possible to achieve a balance of rigidity and stress with the surrounding rigid frame structure, and all members can be optimally designed against seismic forces. Therefore, in this invention, the magnitude of the seismic force generated in the entire frame is smaller than that of a normal rigid frame with shear walls, so the cross-sections of the shear walls and the surrounding frame can be set smaller than the effect of incorporating steel fibers.

[0036] This embodiment provides the following effects. (1) The ancillary columns 21, boundary beams 22, and shear walls 20 are formed from steel fiber reinforced concrete in which steel fibers are mixed in an amount of 0.3% to 2.0% relative to the volume of concrete. As a result, the shear strength and ductility (deformation performance) of the ancillary columns 21, boundary beams 22, and shear walls 20 can be significantly improved. As a result, the steel fibers provide a reinforcing effect equivalent to or greater than that of shear reinforcement bars, eliminating the need to densely reinforce the shear walls 20 and boundary beams 22 with shear reinforcement bars. Consequently, the width W1 of the ancillary columns 21 can be reduced to 1.0 times the wall thickness W2 of the shear wall 20, ensuring a user-friendly interior space while achieving a shear wall 20 with excellent load-bearing capacity and deformation performance. Furthermore, since the auxiliary columns 21 are made of steel fiber reinforced concrete, the deformation performance of the auxiliary columns 21 is improved, so even if the width W1 of the auxiliary columns 21 is set to 1.0 times the wall thickness W2 of the load-bearing wall, excellent deformation performance can be ensured. Furthermore, when designing the structure of building 1, members constructed with steel fiber reinforced concrete can be evaluated to have significantly greater shear strength, making it possible to reduce the size of the members and the amount of reinforcement compared to ordinary reinforced concrete members. In other words, the wall thickness W2 of the shear wall 20 can be made thinner, and the amount of shear reinforcement in the boundary beam 22 can be reduced (or its strength reduced). Because the wall thickness of the shear wall 20 can be made thinner, the concentration of seismic force on the shear wall 20 is suppressed, so it is possible to balance the rigidity and stress with the rigid frame structure surrounding the shear wall 20, and all members can be optimally designed against seismic forces.

[0037] (2) The boundary beam 22 was formed of steel fiber reinforced concrete in which steel fibers were mixed in an amount of 0.3% to 2.0% relative to the volume of concrete. As a result, the steel fibers exert a reinforcing effect equivalent to or greater than that of shear reinforcement, so the width W3 of the boundary beam 22 could be made small, to 1.0 times the wall thickness W2 of the load-bearing wall, and a beam with excellent load-bearing capacity and deformation performance could be realized while ensuring a user-friendly interior space. (3) Above the ancillary columns 21 and seismic walls 20 formed of steel fiber reinforced concrete, ancillary columns 21A and seismic walls 20A formed of concrete without steel fibers are provided. Furthermore, the main reinforcement bars 41 of the ancillary columns 21 and the main reinforcement bars 41 of the ancillary columns 21A are connected, and the vertical reinforcement bars 31 of the seismic walls 20 and the vertical reinforcement bars 31 of the seismic walls 20A are connected. Thus, even if all the ancillary columns 21, 21A and seismic walls 20, 20A of the building 1 are not formed of steel fiber reinforced concrete, a building 1 with excellent shear strength and deformation performance can be realized.

[0038] [Second Embodiment] Figure 10 is a plan view of building 1A according to a second embodiment of the present invention. Figure 11 is a side view of building 1A in Figure 10. This embodiment differs from the first embodiment in that the seismic wall 20, ancillary columns 21, and boundary beam 22 are arranged along the outer perimeter of building 1A. According to this embodiment, the same effects as those described in (1) to (3) above are obtained.

[0039] Furthermore, the present invention is not limited to the embodiments described above, and any modifications, improvements, etc., that can achieve the objectives of the present invention are included within the scope of the present invention. For example, in each of the embodiments described above, building 1 was made to be nine stories tall, but it is not limited to this, and any building with two or more stories will suffice. Furthermore, in each of the embodiments described above, seismic walls 20 are provided on both of the pair of ancillary columns 21 connected by the boundary beam 22. However, the invention is not limited to this, and as shown in Figure 12, seismic walls 20 may be provided on only one of the pair of ancillary columns 21 connected by the boundary beam 22. Furthermore, in the first embodiment described above, a seismic wall 20, ancillary columns 21, and boundary beams 22 were provided in the X direction of the building 1, and a seismic wall 10 without openings was provided in the Y direction of the building 1. However, the invention is not limited to this, and seismic walls and boundary beams may also be provided in the Y direction of the building. Furthermore, in the first embodiment described above, the rigid frame structure was provided only in one span at both ends of the building 1 in the X and Y directions, but it is not limited to this and may be provided over several spans.

[0040] Furthermore, in the embodiments described above, the auxiliary columns, seismic walls, and boundary beams were formed from steel fiber reinforced concrete, but the invention is not limited to steel fiber reinforced concrete. They may be formed from any of the following materials: vinylon PVA fiber reinforced concrete, PP fiber reinforced concrete, basalt fiber reinforced concrete, cellulose nanofiber CNF fiber reinforced concrete, and fiber-reinforced cement composite material (FRCC). Furthermore, in the embodiments described above, the ancillary columns and seismic walls on the first and second floors are formed from steel fiber reinforced concrete, and the boundary beams on all floors are also formed from steel fiber reinforced concrete, but the invention is not limited to this. Depending on the construction site and shape of the building, it is preferable to form the boundary beams located below the ground floor (1 / 5th floor or less) from steel fiber reinforced concrete. [Explanation of Symbols]

[0041] 1, 1A... Building (structure) 2... Column 3... Beam 4... Core 10...Seismic wall in the Y direction 10A...Seismic wall in the Y direction 20...Shear wall in the X direction (load-bearing wall) 20A...Shear wall in the X direction (second load-bearing wall) 21...Auxiliary column (column) 21A...Auxiliary column (second column) 22...Boundary beam (beam) 22A...Boundary beam (second beam) 23...Wall beam 30...Concrete body 31...Vertical reinforcement 32...Horizontal reinforcement 33...Main beam reinforcement 40...Concrete body 41...Main reinforcement for columns 42...Hoop reinforcement 50...Concrete body 51...Main beam reinforcement 52...Stirrup

Claims

1. A structure comprising a reinforced concrete frame, The reinforced concrete frame of the core section of the lower part of the aforementioned structure consists of a pair of reinforced concrete columns, A reinforced concrete beam connecting the tops of the aforementioned columns, A load-bearing wall made of reinforced concrete is joined to at least one of the pair of columns, The reinforced concrete frame of the core section directly above the lower section comprises a pair of second reinforced concrete columns provided on top of the aforementioned columns, A second reinforced concrete load-bearing wall is provided on top of the aforementioned load-bearing wall, The structure comprises a second reinforced concrete beam connecting the tops of the second columns, The length of the beam's axis is shorter than the width of the load-bearing wall. The width of the column is 1.0 times or more and less than 2.0 times the wall thickness of the load-bearing wall. The concrete bodies of the columns, beams, and load-bearing walls are formed of fiber-reinforced concrete in which fibers are mixed in at a concentration of 0.3% to 2.0% relative to the volume of the concrete. The concrete bodies of the second column and the second shear wall are formed of ordinary concrete without fiber inclusions. The main reinforcement bars of the aforementioned column are connected to the main reinforcement bars of the second column via a reinforcement bar splice. A structure characterized in that the vertical reinforcement bars of the load-bearing wall are connected to the vertical reinforcement bars of the second load-bearing wall via reinforcement bar splices.

2. The structure according to claim 1, characterized in that the width of the beam is 0.5 times or more the wall thickness of the load-bearing wall.

3. The structure according to claim 1 or 2, characterized in that the lower part is the first floor and the second floor.

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