Beam structure and beam design method

Abstract

To provide a beam structure and a beam design method for a beam in which a yield hinge is unlikely to form on a beam end.SOLUTION: A beam structure has: a reinforced concrete-made beam 16 having a straight line part 16A, and a bent part 16B which is formed on both ends or one end of the straight line part 16A and is provided in a direction crossing the straight line part 16A, wherein the beam is joined to a column 12; and a reinforcement material 20 which is arranged from the column 12 through the bent part 16B to the straight line part 16A, and has one end part arranged in the straight line part 16A.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a beam structure and a method for designing a beam. [Background technology]

[0002] The following Patent Document 1 describes a design support system that uses BIM to design floors and balconies at building construction sites. In this design support system, when a bent beam (a beam that is bent when viewed from above) is included as a beam model, a node is set including the bending point of the bent beam, and floors and balconies are added to a column-beam structure based on the area value of a figure enclosed by a loop going around the node. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-174427 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in the above-mentioned Patent Document 1, a building may have a folded beam. For example, when a corner cut is provided at a corner of a building, a beam provided at the corner may be folded between two columns.

[0005] The ends of such bent beams are subjected to torsional stress as well as bending stress. However, if a yield hinge is planned to occur at the end of the beam where torsional stress occurs, it is difficult to grasp the shear force that can be borne and the timing at which the yield hinge will occur, making the design difficult.

[0006] In consideration of the above, the present invention aims to provide a bent beam structure and a beam design method in which yield hinges are less likely to occur at the beam ends. [Means for solving the problem]

[0007] The beam structure of claim 1 comprises a reinforced concrete beam having a straight portion and a bent portion formed at both ends or one end of the straight portion and extending along a direction intersecting the straight portion, the beam being joined to a column, and a reinforcing member arranged from the column via the bent portion to the straight portion and having one end arranged on the straight portion.

[0008] In the beam structure of claim 1, a bent portion is formed in the beam and the bent portion is joined to the column. Therefore, bending stress and torsional stress are generated at the end of the beam. In such a beam structure, when an earthquake force acts on the beam, a yield hinge is likely to occur at the end of the beam.

[0009] However, this beam structure is equipped with a reinforcing material. The reinforcing material is arranged from the column through the bent portion to the straight portion, and one end portion is arranged on the straight portion. As a result, the yield hinge is likely to occur not at the end of the beam, but at the boundary between the portion where the reinforcing material is arranged and the portion where the reinforcing material is not arranged in the straight portion. As a result, since there is no need to assume a yield hinge at the end of the beam where both bending stress and torsional stress occur, it is easy to grasp the shear force that can be borne and the timing when a yield hinge will occur.

[0010] A beam structure according to a second aspect of the present invention is the beam structure according to the first aspect, wherein the reinforcing material is a reinforcing bar, and a fastener is provided at the one end of the reinforcing material.

[0011] In the beam structure of claim 2, the reinforcing material is a reinforcing bar, and a fixing device is provided at the end. Therefore, a bearing stress is generated between the fixing device and the concrete. This eliminates the need to bend the reinforcing bar, and improves the strength of the beam end.

[0012] A beam structure according to claim 3 is the beam structure according to claim 1 or 2, in which the beam is provided at a corner of a building.

[0013] The beam structure of claim 3 makes it easy to design buildings with corner cuts at the corners.

[0014] The beam design method of claim 4, in the beam structure described in claim 1, calculates the bending stress and torsional stress acting on the connection part of the beam with the column from the bending stress at the one end of the reinforcing material, and determines the strength of the reinforcing material.

[0015] According to the beam design method of claim 4, it is possible to generate a yield hinge not at the beam end but at the end of a straight portion where there is no reinforcement material. Effect of the Invention

[0016] According to the present invention, yield hinges are less likely to occur at the ends of the beams. [Brief description of the drawings]

[0017] [Figure 1] 1 is a plan view showing a building to which a beam structure according to an embodiment of the present invention is applied. [Diagram 2] FIG. 1A is a plan view showing a beam structure according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line BB in FIG. [Diagram 3] FIG. 1A is a schematic diagram showing a method for designing a beam according to an embodiment of the present invention; FIG. 1B is a bending stress diagram showing the relationship between the bending stress at points C and D and the bending stress at points B and E; FIG. 1C is a diagram showing the bending stress and its component forces at point B in FIG. 1A; and FIG. 1D is a diagram showing the bending stress at point D in FIG. [Figure 4] FIG. 13 is a plan view showing a modified example of a beam structure according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a beam structure according to an embodiment of the present invention will be described with reference to the drawings. Components indicated by the same reference numerals in each drawing are the same components. However, unless otherwise specified in the specification, each component is not limited to one, and may be present in multiple numbers.

[0019] In addition, explanations of configurations and symbols that are duplicated in each drawing may be omitted. Note that the present disclosure is not limited to the following embodiments, and may be implemented by making appropriate modifications, such as omitting configurations, replacing them with different configurations, or combining one embodiment and various modified examples, within the scope of the purpose of the present disclosure.

[0020] In each drawing, the directions indicated by the arrows X and Y are directions along a horizontal plane and are perpendicular to each other. The direction indicated by the arrow Z is a direction along the vertical direction (up and down direction). The directions indicated by the arrows X, Y, and Z in each drawing are assumed to be mutually consistent.

[0021] <Beam structure> (building) Fig. 1 shows a building 10 to which a beam structure according to an embodiment of the present invention is applied. The building 10 is a structure having a column and beam structure made of reinforced concrete. In this column and beam structure, beams 14 installed on columns 12 are arranged along the X and Y directions.

[0022] The building 10 has a corner portion E1 where a corner cutting is provided. A beam 16 that is bent in a top view is arranged in the corner portion E1. An exterior wall (not shown) is provided along the beam 16, thereby forming the corner cutting in the building 10.

[0023] (Example of beam structure) Figure 2(A) shows an enlarged view of a corner portion E1 enclosed by a dashed line in Figure 1. As shown in this figure, a reinforced concrete beam 16 has a straight portion 16A and a bent portion 16B.

[0024] The straight portion 16A is a portion whose extension direction is inclined with respect to the X direction and the Y direction, and is formed in the center of the beam 16. The bent portions 16B are formed on both ends of the straight portion 16A, and are two portions along a direction intersecting the straight portion 16A. The bent portions 16B each extend along the X direction and the Y direction. Each bent portion 16B is connected to the pillar 12.

[0025] A reinforcing material 20 is arranged in the beam 16. The reinforcing material 20 is a reinforcing bar laid horizontally inside the beam 16. One end of the reinforcing material 20 is arranged in the straight portion 16A, and is arranged to the column 12 via a bent portion, and the other end is bent inside the column 12 and fixed to the column 12 as shown in FIG. 2(B). Note that the dashed dotted line M in FIG. 2(B) indicates the boundary between the straight portion 16A and the bent portion 16B. The reinforcing material 20 is bent in this portion.

[0026] The reinforcement members 20 are arranged in two stages, below the upper end reinforcement 30A and above the lower end reinforcement 30B of the beam main reinforcement, in a side view. The position of the reinforcement members 20 in a side view may be changed as appropriate, and may be arranged in one stage, for example, at the same height as the upper end reinforcement 30A and the lower end reinforcement 30B. Alternatively, the reinforcement members 20 may be arranged in three or more stages.

[0027] 2(A), a plurality of reinforcing members 20 are arranged in the beam width direction when viewed from above. Note that, although the number of reinforcing members 20 when viewed from above is four in FIG. 2(A), the number can be changed as appropriate.

[0028] The end of the reinforcing material 20 located on the straight portion 16A is provided with a fastener 22 for mechanically fixing the reinforcing material 20 to concrete. Note that a hook may be formed on the end of the reinforcing material 20 instead of the fastener 22. Also, the end located on the pillar 12 may be provided with a fastener 22 instead of being bent. Alternatively, the end located on the pillar 12 may be located on the beam 14 instead of the pillar 12.

[0029] <Beam design method> The above-mentioned design method for the beam 16 and the reinforcement material 20 calculates the bending stress and torsional stress acting on the connection part of the beam 16 with the column 12 from the bending stress at the boundary part between the part where the fastener 22 is located and the part where it is not located (in other words, the end part of the reinforcement material 20 located at the straight part 16A), and determines the strength of the reinforcement material 20.

[0030] Specifically, as shown in Fig. 3(A), the connection point between one column 12 and beam 16 (bend portion 16B) is defined as point A, and the connection point between the other column 12 and beam 16 (bend portion 16B) is defined as point F. The intersection point between straight line portion 16A on the point A side and bend portion 16B is defined as point B, the end of reinforcement material 20 (see Fig. 2(A)) arranged on straight line portion 16A on the point A side is defined as point C, the end of reinforcement material 20 arranged on straight line portion 16A on the point F side is defined as point D, and the intersection point between straight line portion 16A on the point F side and bend portion 16B is defined as point E. Note that points A, B, C, D, E, and F are each points on the central axis of beam 16.

[0031] As shown in Figure 3(A) and (B), the bending stresses along the axial direction of the straight section 16A at points C and D during an earthquake are C M', D M', the distance between points C and D on the straight line is L, and the distance between points B and C is L BC , the distance between point D and point E is L DE In this case, the following shear force exists between points BE. Q E is the bending stress at point B and point E respectively. B M' and E M' is produced.

[0032] Q E=( C M'+ D M') / L B M'= C M'+ Q E.L. BC E M'= D M'+ Q E.L. DE

[0033] Here, as shown in FIG. 3(C), the bending stress along the material axis direction of the straight portion 16A at point B is B M' is the stress in the axial direction (Y direction) of the bent portion 16B. B The stress is decomposed into a stress M in a direction perpendicular to the direction of the bending stress, and a stress T in a direction perpendicular to the direction of the bending stress. If the angle between the axial direction of the straight portion 16A and the material axis of the bent portion is θ, it can be expressed as follows.

[0034] BM= B M'cosθ T= B M'sinθ

[0035] As shown in Figure 3(A), if the distance between points B and A along the axial direction of the beam end is La, the following stress acts on point A.

[0036] Bending stress: A M= Q E·La+ B M Torsional stress: T

[0037] Where: C M', D The bending stress at point A obtained when M' is the yield bending stress A The strength of the reinforcing material 20 is determined so that the yield strength of the end portion (point A) of the beam 16 exceeds the force M and the torsional stress T. The strength of the reinforcing material 20 can be determined by adjusting the material, diameter, number, etc. of the reinforcing material 20.

[0038] As a result of the above, a yield hinge can be generated not at the end of the beam 16 but at the end of the straight portion 16A where no reinforcing member 20 is present.

[0039] <Action and Effects> In the beam structure according to the embodiment of the present invention, a bent portion 16B is formed in the beam 16, and the bent portion 16B is joined to the column 12. Therefore, bending stress and torsional stress are generated at the end of the beam 16 (the connection portion with the column 12). In such a beam structure, normally, when an earthquake force acts on the beam, a yield hinge is likely to occur at the end of the beam 16.

[0040] However, this beam structure includes a reinforcing member 20. The reinforcing member 20 is disposed from the pillar 12 through the bent portion 16B to the straight portion 16A, and one end portion (the portion where the fastener 22 is provided) is disposed in the straight portion 16A.

[0041] As a result, yield hinges are likely to occur not at the ends of the beam 16, but at the boundaries between the parts of the straight section 16A where the reinforcement material 20 is disposed and the parts where it is not disposed. As a result, it is not necessary to assume yield hinges at the ends of the beam 16 where both bending stress and torsional stress occur, making it easy to grasp the shear force that the member can withstand and the timing at which a yield hinge will occur.

[0042] <Other embodiments> In the above embodiment, the beam 16 has the bent portions 16B formed at both ends of the straight portion 16A, but the embodiment of the present invention is not limited to this. For example, as shown in Fig. 4, the bent portion 16B may be formed at only one end of the straight portion 16A. In such a shape, it is possible to suppress the occurrence of a yield hinge at the boundary between the bent portion 16B and the column 12 to which the bent portion 16B is connected.

[0043] When the beam 16 is formed in this manner, point D in the beam design method described above is set at the boundary between the straight line portion 16A and the column 12. In this manner, the present invention can be embodied in various aspects. [Explanation of symbols]

[0044] 10. Building 12 Pillars 16 Beam 16A Straight section 16B Folding part 20 Reinforcement 22 Fixtures

Claims

1. A reinforced concrete beam having a straight portion and a bent portion formed at both ends or one end of the straight portion and extending along a direction intersecting the straight portion, the beam being joined to a column; A reinforcing member is disposed from the column through the bent portion to the straight portion, and one end of the reinforcing member is disposed on the straight portion; A beam structure with

2. The reinforcing material is a steel bar, and a fastener is provided at the one end of the reinforcing material. The beam structure of claim 1 .

3. The beam is provided at a corner of the building. A beam structure according to claim 1 or 2.

4. 2. A beam design method for a beam structure according to claim 1, comprising the steps of: calculating bending stress and torsional stress acting on a connection portion of the beam with a column from the bending stress at the one end of the reinforcing material; and determining the strength of the reinforcing material.

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