Reinforced Concrete Structures

Abstract

To provide a reinforced concrete structure that can be safely and efficiently constructed to replace conventional RC structures.SOLUTION: The reinforced concrete structure 1 has a plurality of tensile reinforcing members 3, 3 ... having a certain length embedded in a concrete 2 at intervals. The tensile reinforcing members 3, 3 include an elongated plate-like web portion 4, flange portions 5, 5 projecting from both side portions of the web portion 4 in a direction crossing the front surface and the back surface of the web portion 4, and adhesion strengthening means 6, 6... for adhering the web portion 4 and the concrete 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates mainly to reinforced concrete structures having large cross sections such as bridge piers, beams, girders, footings and other foundations. [Background technology]

[0002] Although concrete has a high resistance to compressive forces, it is weak against tensile forces. Therefore, reinforced concrete (RC) structures, in which tensile reinforcing members such as steel bars, which have high resistance to tensile forces, are embedded in the concrete, are widely used for concrete structures.

[0003] Conventionally, in this type of RC structure, the diameter, number, and arrangement of rebars are determined based on the cross-sectional shape of the structure, the required bending strength and shear strength, and other conditions (see, for example, Patent Document 1).

[0004] In particular, in large cross-section concrete structures such as bridge pier foundation structures, the required bending strength and shear strength are large, so a large amount of reinforcing bars is needed, and therefore the number and diameter of reinforcing bars often increase accordingly. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-204861 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, standards for seismic design have been revised to deal with increasingly large earthquakes, and as a result, there are many cases in which high bending and shear strength is required, and in such cases over-dense rebars have become a problem.

[0007] With this type of overcrowded reinforcement, a large number of thick rebars are placed at small intervals (for example, 100 to 150 mm pitch), which can lead to reduced work efficiency due to the complexity of rebar assembly and inspection work, and can also compromise the safety of workers due to limited working space.

[0008] Furthermore, overly dense reinforcement raises concerns about the filling ability of concrete when pouring, which could lead to a decline in the quality of reinforced concrete structures.

[0009] On the other hand, in this type of RC structure 20, for example, as in the structure shown in Figure 6, a group of main reinforcing bars consisting of multiple reinforcing bars 22, 22... arranged at intervals within concrete 21 may be arranged in multiple rows vertically or horizontally at intervals in a cross section perpendicular to the reinforcing bar axis of the structure.

[0010] When unitizing this type of main reinforcing bar group, the reinforcing bars are usually tied together with tie wires, making it difficult to transport and install the reinforcing bar groups assembled in advance in a factory or the like in multiple upper and lower tiers to the construction site.

[0011] For this reason, it is difficult to prefabricate the reinforcing bars, and when arranging multiple layers of reinforcing bars above and below, the lower layer of reinforcing bars must be assembled at the construction site, and then a stand (a so-called horse stand) made of steel must be installed in advance, and the upper layer of reinforcing bars must be assembled while supported by this stand, resulting in poor work efficiency.

[0012] In view of the above-mentioned conventional problems, the present invention has been made with an object to provide a reinforced concrete structure which can be constructed safely and efficiently as an alternative to conventional RC structures. [Means for solving the problem]

[0013] The feature of the invention described in claim 1 for solving the above-mentioned conventional problems is to provide a method for manufacturing a concrete structure having a plurality of gypsum laths, the gypsum laths being arranged at intervals in the concrete structure, Compared to steel barsIn a reinforced concrete structure in which a plurality of tensile reinforcement members having a certain length and high resistance to tensile force are embedded, the tensile reinforcement members are comprised of a long and narrow flat web portion, flange portions projecting from both sides of the web portion in a direction intersecting the front and / or back surface of the web portion, and a plurality of members projecting from the front and / or back surface of the web portion, and are provided with an attachment strengthening means for attaching the web portion to the concrete. , and is placed in the concrete with its weak axis facing the direction in which the bending moment assumed in the design acts. The point is...

[0014] Claim 2 The invention described in is characterized in that Claim 1 In addition to the above configuration, the adhesion strengthening means comprises a plurality of rod-shaped members protruding from the front and / or back surface of the web portion.

[0015] Claim 3 The invention described in is characterized in that Claim 2 In addition to the above configuration, the rod-shaped member has an adhesion enhancing recess formed on its outer circumferential surface.

[0016] Claim 4 The invention described in is characterized in that Claim 2 or 3 In addition to the above configuration, the rod-shaped member has an enlarged diameter portion at its head.

[0017] Claim 5 The invention described in is characterized in that Claims 2 to 4 In addition to any one of the above configurations, the rod members are arranged in a staggered pattern on the front or back surface of the web portion.

[0018] Claim 6 The invention described in is characterized in that Claims 2 to 5 In addition to any one of the configurations above, the flange portion is formed with a width at which the compressive force generated by the Poisson effect of the web portion can act effectively, and the number of the rod-shaped members is sized to be capable of withstanding a shear force equal to the axial yield tensile force of the tensile reinforcement member minus the force due to the frictional force generated between the flange portion and the concrete due to the Poisson effect of the web portion.

[0019] Claim 7 The invention described in is characterized in that Claims 1 to 6 In addition to any one of the above configurations, the present invention further comprises a reinforcing member group in which a plurality of the tensile reinforcing members arranged at intervals from one another are connected by a connecting member.

[0020] Claim 8 The invention described in is characterized in that Claim 7 In addition to the above configuration, the reinforcing member groups are arranged in the concrete at intervals from one another, and the reinforcing member groups are connected to each other by group connecting members. Effect of the Invention

[0021] By having the configuration of claim 1, the reinforced concrete structure of the present invention can bear the tensile force that would be borne by multiple reinforcing bars in a conventional reinforced concrete structure with a single tensile reinforcement member, and therefore the number of tensile reinforcement members can be smaller than the number of reinforcing bars in a conventional reinforced concrete structure, thereby avoiding over-dense reinforcement and enabling efficient construction. In addition, a sufficient effective height of the tensile reinforcement member relative to the concrete can be ensured, and the concrete cross section can be made small so as to achieve a predetermined effective height.

[0022] In the present invention, Claims 2 to 4 By providing the above configuration, it is possible to ensure higher adhesive strength between the tensile reinforcement member and concrete, and to disperse cracks that occur in the concrete. Furthermore, by providing the configurations of claims 4 and 5 in this invention, a force (compressive force) perpendicular to the web portion acts on the concrete by the rod-shaped member, and a biaxial compressive force acts on the concrete together with the compressive force between both web portions due to the Poisson effect of the web portions, so that a high frictional force is generated between the concrete and the web portion, and a high frictional force can be obtained between the tensile reinforcement member and the concrete.

[0023] Further, in the present invention, Claim 5 By adopting this configuration, it is possible to disperse the occurrence of cracks in the concrete.

[0024] Furthermore, in the present invention, Claim 6By adopting this configuration, when a tensile force is applied to the tensile reinforcement member, the Poisson effect of the web portion reduces the distance between the opposing flange portions, thereby causing the flange portions to restrain the concrete, and the frictional force between the flange portions and the concrete increases, thereby reducing the burden on the rod-shaped members and making it possible to reduce the number of rod-shaped members.

[0025] In the present invention, Claims 7 to 8 By adopting the above configuration, the structure can be prefabricated using tensile reinforcement members, and the reinforcement members can be preassembled in a factory on land or the like, and then transported and installed in the assembled state all at once, thereby reducing the labor required at the construction site. [Brief description of the drawings]

[0026] [Figure 1] 1 is a cross-sectional view showing an example of a reinforced concrete structure according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line XX of the same. [Diagram 3] 1, (b) is a plan view of the same, (c) is a plan view of another example of the same, and (d) is an enlarged cross-sectional view of another example of the same tensile reinforcement member. [Figure 4] 4(a) is a flowchart showing a method for designing a rod-shaped member of the tensile reinforcement member of the above embodiment, and FIG. 4(b) is a flowchart showing a method for calculating frictional force in the above flowchart. [Diagram 5] FIG. 4 is a perspective view showing the assembled state of the tensile reinforcement member group of the same. [Figure 6] FIG. 1 is a cross-sectional view showing an embodiment of a conventional reinforced concrete structure (RC structure). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Next, an embodiment of the reinforced concrete structure according to the present invention will be described based on the examples shown in Figures 1 to 5. In the figures, reference numeral 1 denotes a reinforced concrete structure, and reference numeral 20 denotes a conventional reinforced concrete structure. Note that the same reference numerals will be used to designate the same components as in the above-mentioned embodiments.

[0028] In addition, in the present invention, tie bars, stirrup bars, etc. may be used, but in this embodiment, for the sake of convenience, illustrations of such bars are omitted in order to make the contents of the present invention easier to understand.

[0029] The reinforced concrete structure 1 has a plurality of tensile reinforcement members 3, 3 . . . embedded at intervals in concrete 2, forming an RC structure that replaces a conventional reinforced concrete structure 20.

[0030] Here, the reinforced concrete structure includes not only an RC structure using tensile reinforcement members 3, 3 instead of general rod-shaped reinforcing bars 22, 22..., but also an RC structure using both tensile reinforcement members 3, 3... and rod-shaped reinforcing bars 22, 22. In the present invention, rod-shaped reinforcing bars 22 may also be used in combination depending on the shape of the structure to be manufactured, construction conditions, etc.

[0031] As shown in Figure 3, the tensile reinforcement members 3, 3... are made of steel such as H-shaped steel or I-shaped steel, and include a thin, flat web portion 4, thin, flat flange portions 5, 5 protruding from both sides of the web portion 4 in a direction intersecting the front and back surfaces, and an adhesion strengthening means for strengthening the adhesion between the web portion 4 and the concrete 2.

[0032] The web portion 4 is formed into a long, thin, flat plate with a certain length L that satisfies the effective anchorage length with the concrete, for example, a length that is at least six times the width H of the web portion 4, and flange portions 5, 5 are formed integrally with both sides thereof.

[0033] The flange portions 5, 5 extend in directions intersecting the front and back surfaces of both sides of the web portion 4, which in this embodiment are perpendicular to the front and back surfaces, so that the flange portions 5, 5 and the web portion 4 form an I-shaped or H-shaped cross section.

[0034] The effective width b on one side of the width B on one side of the flange portions 5, 5 is a width within which the compressive force generated by the Poisson effect when a tensile force acts on the web portion 4 effectively acts, and is formed, for example, to a width approximately twice the plate thickness t2 of the flange portions 5, 5.

[0035] Therefore, the flange portion 5 has a side width B shorter than the width of the web portion 4, and although it is classified as an H-shaped steel, the cross section is I-shaped.

[0036] In the above embodiment, the flange portions 5, 5 are described as protruding from the front and back sides of the web portion 4, respectively. However, as shown in FIG. 3(d), the flange portions 5, 5 may protrude from only one side, either the front or back side, like a channel steel, etc.

[0037] As shown in Figure 3, the adhesion strengthening means comprises a plurality of rod-shaped members 6, 6... protruding from the front and back surfaces of the web portion 4, and these rod-shaped members 6, 6... are embedded in the concrete 2 so that the web portion 4 and the concrete 2 are firmly attached to each other.

[0038] The rod-shaped members 6, 6 . . . have a round bar-shaped main body 6a whose lower end is fixed to the web portion 4 by welding, and an enlarged diameter portion 6b integrally supported by the head of the main body 6a.

[0039] The means for fixing the rod-shaped member 6 is not limited to welding. For example, holes may be drilled in the web portion and the web may be fitted therein, or the rod-shaped member 6 may be fixed by screws.

[0040] The rod-shaped member 6 is formed, for example, to have approximately the same height as one side width B of the web portion 4. The height of the rod-shaped member 6 is not limited to this embodiment, and can be any height.

[0041] Headed studs available on the market can be used as the rod-shaped members 6, 6.... The rod-shaped members 6, 6... may be so-called headless studs that do not have the enlarged diameter portion 6b at the head.

[0042] The rod-shaped members 6, 6... are not limited to the above-mentioned embodiment, and although not shown, may be ones having a recess for strengthening adhesion formed on the outer periphery like a deformed reinforcing bar, or may have an enlarged diameter portion 6b at the head of a main body portion 6a having a recess for strengthening adhesion. Furthermore, the rod-shaped members 6, 6... may be replaced by bolts, screws, etc.

[0043] The rod-shaped members 6, 6... may be arranged in an aligned manner (aligned arrangement) in which the positions of adjacent rod-shaped members 6, 6... in the width direction are aligned in the longitudinal direction of the web portion 4, as shown in Figure 3(b), or they may be arranged in a staggered manner (staggered arrangement) in which the positions of adjacent rod-shaped members 6, 6... are shifted by a predetermined interval in the longitudinal direction of the web portion 4, as shown in Figure 3(c).

[0044] The number of rod-shaped members 6, 6... is determined based on the steps in the flowchart shown in Figure 4(a). However, the Poisson effect of the web portion 4 reduces the distance between the opposing flange portions 5, 5, allowing the flange portions 5, 5 to restrain the concrete, bear part of the axial yield tensile force, and reduce the burden on the rod-shaped members 6, 6..., so that the number can be reduced.

[0045] Specifically, first, a steel material is selected (s1) such that the tensile yield strength fym×Am of a single steel material is greater than the yield tensile strength fys×As of the corresponding multiple reinforcing bars 22, and the tensile yield strength T=fym×Am of the tensile reinforcement member 3 is calculated (s2). Here, fys is the tensile yield strength of the reinforcing bar, fym is the tensile yield strength of the steel material, Am is the cross-sectional area of ​​the single steel material, and As is the cross-sectional area of ​​the corresponding multiple reinforcing bars.

[0046] Next, the friction force T1 = τ × 2b × L × 2 that the flanges 5, 5 can bear is calculated (s3). Here, τ is the friction stress acting on the inside of the flanges 5, 5 when the web yields, b is the effective width on one side of the flanges 5, 5, and L is the effective fixed length of the web 4.

[0047] A specific method for calculating the frictional force T1 that can be borne by the flange portion 5 will be described below with reference to the flowchart shown in FIG.

[0048] The effective anchorage length L is assumed to be L = 6 × H based on experiments, etc. (s31), and based on this, the effective compressive force Tx due to the Poisson effect when an axial tensile force is applied is calculated using the following equation (s32). Tx = E ν εfw Ae = E ν Ae Ty / (E Aw) = Ty ν Ae / Aw

[0049] Here, E is Young's modulus, ν is Poisson's ratio, εfw is the yield strain of the web portion 4, Ae is the effective anchorage cross-sectional area of ​​the web portion 4 (Ae = t1 x L), Aw is the cross-sectional area of ​​the web portion 4 (Aw = t1 x H), and Ty is the yield tensile force of the web.

[0050] Next, the effective width b of the flanges 5, 5 on one side when the effective compressive force Tx and the empirical rule obtained through experiments are applied is assumed to be b = 2 × t2 (s33), where t2 is the plate thickness of the flanges 5.

[0051] Then, the compressive stress σ=Tx / (b×L×2) acting from the opposing flanges 5,5 toward the concrete on the inside is calculated, and the frictional stress τ=σ×μ acting on the inside of the flanges 5,5 when the webs yield is calculated (s34), where μ is the coefficient of friction between the concrete and steel.

[0052] Through the above procedure, the friction force T1=τ×2b×L×2 acting between the flange portions 5, 5 and the concrete 2 is calculated.

[0053] Then, based on the axial yield tensile force T of the entire tensile reinforcement member 3 obtained through the above procedure and the friction force T1 that can be borne by the flange portion 5, the shear force T2 = T-T1 to be borne by the rod-shaped members 6, 6... is calculated (s4).

[0054] Finally, the number and arrangement of the rod-like members 6, 6... are determined based on the obtained shear force T2 to be borne by the rod-like members 6, 6... (s5).

[0055] The number and arrangement of the rod-like members 6, 6 . . . can be determined based on a design method using general headed studs described in the Standard Specifications for Composite Structures, Specifications for Highway Bridges, and the like.

[0056] Each of the tensile reinforcement members 3, 3... thus constructed is placed in the concrete with its weak axis facing the direction in which the bending moment assumed in the design acts, as shown in Figs.

[0057] In other words, if the strong axis side of the tensile reinforcement member 3 is placed facing the upper and lower surfaces (hereinafter referred to as concrete surfaces) 2a, 2b of the concrete 2 on which the bending moment assumed in the design acts, the effective height of the cross section will be small, as in an SRC structure. Therefore, the weak axis side, i.e., the web portion 4 is placed so that it is parallel to the concrete surfaces 2a, 2b, and the member is embedded with its longitudinal direction facing in the same direction as conventional reinforcing bars 22, 22....

[0058] This tensile reinforcement member 3 has an I-shaped or H-shaped cross section and is provided with rod-shaped members 6, 6... on the surface of the web portion 4, so that the rod-shaped members 6 apply a force (compressive force) perpendicular to the web portion 4 to the concrete 2, generating high frictional force between the web portion 4 and the concrete 2.

[0059] Furthermore, in this tensile reinforcement member 3, a compressive force between both web portions 5, 5 due to the Poisson effect of the web portion 4 generates a high frictional force between the concrete 2 and both flange portions 5, 5.

[0060] In other words, in addition to the adhesion force of the tensile reinforcement member 3 itself, a biaxial compressive force acts on the concrete 2 inside the tensile reinforcement member 3, generating high frictional forces between the concrete 2 and the web portion 4, and between the concrete 2 and the flange portion 5, thereby enabling a high adhesion force to be obtained between the tensile reinforcement member 3 and the concrete 2.

[0061] The reinforced concrete structure 1 constructed in this manner can replace the multiple reinforcing bars 22, 22... in a conventional reinforced concrete structure 20 with a single tensile reinforcement member 3, and can achieve performance equal to or better than that of the conventional reinforced concrete structure 20 with fewer tensile reinforcement members 3, 3....

[0062] For example, in the conventional reinforced concrete structure 20 shown in FIG. 6, a single tensile reinforcement member 3 can support a plurality of reinforcing bars 22, 22 . . . over two stages.

[0063] Therefore, in this reinforced concrete structure 1, the labor required for assembling and inspecting the tensile reinforcement members 3, 3 . . . is significantly reduced, allowing the structure to be constructed efficiently.

[0064] In this reinforced concrete structure 1, since each of the tensile reinforcement members 3, 3... has a certain rigidity, a group of reinforcement members 9, 9, each of which is made up of a plurality of tensile reinforcement members 3, 3... arranged at intervals from one another and connected by connecting members 8, 8, can be prefabricated in a factory or production yard on land and transported and installed in the assembled state to the construction site. The mode of the connecting members 8, 8 is not limited to the embodiment shown in Fig. 5, and the tensile reinforcement members 3 may be used as the connecting members 8, 8, or steel materials such as I-beams, H-beams, and channel steel, or steel plates, etc. may be used.

[0065] Furthermore, when the reinforcing member groups 9, 9 are arranged at intervals within the concrete 2 as in this embodiment, the upper and lower reinforcing member groups 9, 9 can be connected by group connecting members 10, 10, and the upper and lower reinforcing member groups 9, 9 can be prefabricated.

[0066] In the above embodiment, an example has been described in which rod-shaped members 6 are used as the adhesion strengthening means, but the form of the adhesion strengthening means is not limited to this, and for example, protrusions in shapes other than rod-shaped may be provided on the front and / or back surface of the web portion 4, and rod-shaped members 6 of different diameters and shapes may be used on the front and back surfaces of the web portion 4. Also, the web portion 4 may be formed with holes (generally called a perforated dowel) to improve filling properties of concrete and strengthen adhesion.

[0067] In this embodiment, a structure constituting a bridge pier, etc., has been described as an example, however, the structure based on the present invention is not limited to this embodiment, and can be applied to concrete columns, concrete slabs, footings, and any other concrete structures. [Explanation of symbols]

[0068] 1. Reinforced concrete structures 2. Concrete 3 Tensile reinforcement members 4. Web Section 5 Flange 6 Rod-shaped member 8 Connecting members 9 Reinforcement members 10 Colony connection member

Claims

1. A reinforced concrete structure in which a plurality of tensile reinforcement members having a certain length are embedded in the concrete, the tensile reinforcement members being spaced apart from one another and having a higher resistance to tensile forces than reinforcing bars, The tensile reinforcement member is provided with an attachment strengthening means for attaching the web portion to the concrete, the attachment strengthening means being made of a plurality of members protruding from the front and / or back surface of the web portion and a web portion having a long and narrow flat web portion, flange portions protruding from both sides of the web portion in a direction intersecting the front and / or back surface of the web portion, and A reinforced concrete structure characterized in that it is placed within the concrete with its weak axis facing in the direction of the bending moment assumed in the design.

2. 2. The reinforced concrete structure according to claim 1, wherein the adhesion strengthening means comprises a plurality of rod-shaped members protruding from the front and / or rear surface of the web portion.

3. 3. The reinforced concrete structure according to claim 2, wherein said rod-shaped member has an outer peripheral surface formed with a recess for enhancing adhesion.

4. 4. A reinforced concrete structure according to claim 2, wherein the rod-shaped member has an enlarged diameter portion at a head portion thereof.

5. 5. A reinforced concrete structure according to claim 2, wherein the rod-shaped members are arranged in a staggered pattern on the front or back surface of the web portion.

6. the flange portion is formed with a width at which a compressive force generated by the Poisson effect of the web portion can effectively act, The reinforced concrete structure according to any one of claims 2 to 5, wherein the number of rod-shaped members is such that they can withstand a shear force equal to the axial yield tensile force of the tensile reinforcement member minus the shear force due to the frictional force generated between the flange portion and the concrete due to the Poisson effect of the web portion.

7. 7. The reinforced concrete structure according to claim 1, further comprising a group of reinforcing members each including a plurality of said tensile reinforcing members arranged at intervals from one another and connected by a connecting member.

8. 8. The reinforced concrete structure according to claim 7, wherein the groups of reinforcing members are disposed in the concrete at intervals, and the groups of reinforcing members are connected by group connecting members.

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