Composite beam

Abstract

To form a location hinge at a composite beam.SOLUTION: A web part 33 is in a thin and long plate-like shape which extends along a length. Flange parts 34a, 34b extend along a length, and are coupled in a width direction of the web part 33 and in a thin plate-like shape substantially perpendicular to the web part 33. A border part 35 is coupled to lengthwise end parts of the web part 33 and flange part 34, and is in a plate-like shape substantially perpendicular to a length direction. Rib parts 37a, 37b are coupled to the border part 35 on the opposite side from the web part 33 and flange parts 34a, 34b, and in a plate-like shape substantially parallel with the web part 33. The flange parts 34a, 34b have a haunch part 42 which is wider than other parts within a predetermined range from an end part joined to the border part 35. The border part 35 is arranged in contact with an end surface of a reinforced concrete member.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a composite beam including a reinforced concrete member and a steel frame member.

Background Art

[0002] Patent Document 1 discloses a hinge relocation structure at the yield hinge position occurring at the joint of columns and beams in a reinforced concrete building. Patent Documents 2 and 3 disclose a joining structure of dissimilar members between a steel frame member on the central side of a beam and a reinforced concrete member on the end side of the beam constituting a composite beam.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When attempting to apply the hinge relocation structure of Patent Document 1 to the composite beam of Patent Documents 2 and 3, stress may concentrate on a specific main reinforcement among a plurality of main reinforcements for fixing the reinforced concrete member to the steel frame member. An object of this invention is to solve such problems, for example.

Means for Solving the Problems

[0005] The composite beam comprises a reinforced concrete member provided on the column-beam joint side and a steel member provided on the central side. The steel member has an elongated plate-shaped web portion extending along the longitudinal direction, two elongated plate-shaped flange portions extending along the longitudinal direction and connected in the width direction of the web portion and substantially perpendicular to the web portion, a plate-shaped boundary portion connected to the longitudinal ends of the web portion and flange portion and substantially perpendicular to the longitudinal direction, and a plate-shaped rib portion connected to the boundary portion on the opposite side from the web portion and flange portion and substantially parallel to the web portion. The flange portion has a haunch portion that is wider than the rest of the portion within a predetermined range from the end joined to the boundary portion. The boundary portion is positioned in contact with the end face of the reinforced concrete member. The steel frame member may have two or more rib portions. At least two of the rib portions may be spaced apart in a direction substantially perpendicular to the web portion. The distance between at least two of the rib portions may be greater than the width of the portion of the flange other than the haunch portion. The haunch portion may have a substantially constant width within a predetermined range from the end joined to the boundary portion. [Effects of the Invention]

[0006] According to the composite beam described above, a relocation hinge can be formed at a position closer to the center than the haunch section. Furthermore, since stress can be distributed, it is possible to prevent stress from concentrating on specific main reinforcement bars. [Brief explanation of the drawing]

[0007] [Figure 1] An example of a part of a building - a cross-sectional view seen from the Y direction. [Figure 2] An example of a part of the building - a cross-sectional view seen from the Z direction. [Figure 3] A cross-sectional view from the +X direction, showing an example of a part of the building. [Figure 4] An example of a steel frame member is shown - a view from the Y direction. [Figure 5]A view from the +Z direction showing an example of a part of a steel frame member. [Figure 6] A cross-sectional view from the +X direction showing an example of a steel frame member. [Figure 7] An example of a steel frame member is shown - a view from the X direction. [Modes for carrying out the invention]

[0008] Building 10 will be described with reference to Figures 1-3. The building 10 has, for example, columns 11, slabs 12, and beams 13-15. Column 11 extends in the vertical direction (±Z direction). Beam 13 extends horizontally (in the +X direction) from the column-beam joint located in the middle of column 11. The beam 14 extends horizontally (in the -Y direction) from the column-beam joint of the column 11. The beam 15 extends horizontally (+Y direction) from the column-beam joint of the column 11. Slab 12 is placed on a plane formed by beams 13-15.

[0009] The beam 13 is a composite beam having a reinforced concrete member 31 and a steel frame member 32. The reinforced concrete member 31 is provided at the end of the beam 13 and is integrally formed with the column-beam joint of the column 11. The reinforced concrete member 31 is configured to have sufficient load-bearing capacity by applying prestress or other means. The steel frame member 32 is provided in the central part of the beam 13 and is fixed to the reinforced concrete member 31 by a plurality of anchoring means 38. The anchoring means 38 includes, for example, a main reinforcing bar embedded in the reinforced concrete member 31 and a nut screwed onto the tip of the main reinforcing bar.

[0010] Refer to Figures 4-7 for a more detailed explanation of the steel frame member 32. The steel frame member 32 is, for example, generally an H-shaped steel. The steel frame member 32 has, for example, a web portion 33, two flange portions 34a and 34b, a boundary portion 35, and two rib portions 37a and 37b. The web portion 33 is an elongated plate shape that is substantially perpendicular to the ±Y direction and extends in the substantially ±X direction. The flange portions 34a and 34b are elongated plate shapes that are substantially perpendicular to the ±Z direction and extend in the substantially ±X direction. That is, the flange portions 34a and 34b are substantially perpendicular to the web portion 33. The central portion of the flange portion 34a is connected to the end portion in the width direction (+Z side) of the web portion 33. The central portion of the flange portion 34b is connected to the end portion in the width direction (-Z side) of the web portion 33. That is, the web portion 33 and the flange portions 34a and 34b form a substantially H shape.

[0011] The shapes of the flange portions 34a and 34b are substantially the same. The flange portion 34a has a constant-width portion 41 and a haunch portion 42. The constant-width portion 41 has a substantially constant width (length in the ±Y direction). The haunch portion 42 (horizontal haunch) is provided in a predetermined range from the end portion in the longitudinal direction (-X side) of the flange portion 34a and has a larger width (length in the ±Y direction) than the constant-width portion 41. The haunch portion 42 has a constant-width portion 43 and a taper portion 44. The constant-width portion 43 is provided in a predetermined range (narrower than the range of the haunch portion 42) from the end portion in the longitudinal direction (-X side) of the flange portion 34a and has a substantially constant width (length in the ±Y direction). The taper portion 44 is provided in the remaining portion of the haunch portion 42, and the width (length in the ±Y direction) gradually decreases as it moves away from the end portion in the longitudinal direction (-X direction) of the flange portion 34a.

[0012] The boundary portion 35 (boundary plate) is a substantially rectangular plate shape that is substantially perpendicular to the ±X direction. The boundary portion 35 is connected to the end portions in the longitudinal direction (-X direction) of the web portion 33 and the flange portions 34a and 34b by welding or the like. The boundary portion 35 has a plurality of fixing holes 36. The fixing holes 36 penetrate the boundary portion 35 in the ±X direction.

[0013] The rib portions 37a and 37b (reinforcement ribs) are elongated plate-like in shape, approximately perpendicular to the ±Y direction, and extend approximately in the ±Z direction. That is, the rib portions 37a and 37b are approximately parallel to the web portion 33. The rib portions 37a and 37b project in the -X direction from the -X side surface of the boundary portion 35. That is, the rib portions 37a and 37b are joined to the boundary portion 35 by welding or other means on the side opposite to the web portion 33 and flange portions 34a and 34b. The rib sections 37a and 37b are spaced apart in the ±Y directions. The distance between the rib sections 37a and 37b is greater than the width of the fixed-width section 41 and less than the maximum width of the haunch section 42 (i.e., the width of the fixed-width section 43). The shapes of the rib sections 37a and 37b are substantially identical. Rib section 37a is roughly rectangular in shape, with the two corners on the -X side beveled at approximately 45 degrees. The size of the bevel is larger on the -Z side than on the +Z side.

[0014] The steel frame members 32 described above are fixed and integrated with the reinforced concrete member 31 to form a beam 13 (composite beam). The +X side end face of the reinforced concrete member 31 is a plane approximately perpendicular to the ±X direction and is provided with grooves that engage with the rib portions 37a and 37b. For example, the tip of the main reinforcement of the anchoring means 38 is inserted through the anchoring hole 36 of the boundary portion 35, and the nut of the anchoring means 38 is screwed onto the tip and tightened. As a result, the boundary portion 35 contacts the +X side end face of the reinforced concrete member 31, and the rib portions 37a and 37b engage with the groove, thereby fixing the steel frame member 32 to the reinforced concrete member 31.

[0015] When a shear force is applied to the beam 13 formed in this manner due to an earthquake or the like, the reinforced concrete member 31 has sufficient strength, and the end of the steel frame member 32 is reinforced by the haunch portion 42, so stress concentrates in the hinge range 39 shown in Figure 4, and a relocation hinge is formed. Furthermore, the stress generated at the boundary portion 35 is distributed in the ±Y direction by the haunch portion 42 and in the ±Z direction by the rib portions 37a and 37b. As a result, the stress is evenly distributed throughout the boundary portion 35, preventing stress from concentrating on any particular anchoring means among the multiple anchoring means.

[0016] The rib portions 37a and 37b may also be rectangular plates without chamfers. Furthermore, there may be three or more rib sections, not just two. For example, a third rib section may be provided at an intermediate position between rib sections 37a and 37b (i.e., on approximately the same plane as the web section 33), or a third and fourth rib section may be provided at equal intervals between rib sections 37a and 37b.

[0017] The embodiments described above are examples intended to facilitate understanding of the present invention. The present invention is not limited thereto and includes various modifications, changes, additions, or deletions without departing from the scope defined by the appended claims. This will be readily apparent to those skilled in the art from the above description.

[0018] In reinforced concrete construction, a promising method for preventing failure of column-beam joints is the hinge relocation design method, which involves planning the hinge position of the beam to be away from the column-beam joint. In contrast, this approach realizes a hinge relocation structure by using a hybrid structure of reinforced concrete and steel for the beam. Conventional methods achieve this by making the load-bearing capacity of the RC beam at the relocation point smaller than the load-bearing capacity of the RC beam itself. However, this method has the drawback of not being able to handle long-span beams. In addition, because relocation shortens the span between hinge locations, the design for shear force on the RC tends to become more stringent. Several hinge relocation technologies already exist, primarily aimed at controlling damage to column-beam joints in reinforced concrete (RC) structures. These technologies relocate the hinge position to the inside of the main beam, rather than at the column edge. However, existing hinge relocation technologies are composed solely of RC materials, making them unsuitable for long-span beams. Furthermore, the reduced shear span between hinges necessitates stricter shear design for the RC beam, requiring measures such as enlarging the cross-section or using high-strength materials. To address this, the hinge relocation section will be constructed using steel (S) to solve the above problem. Specifically, the main reinforcement bars of the end RC are joined to the boundary plate, and horizontal haunches are provided on the flanges of the ends of the S beams to prevent the hinges from extending to the boundary plate. These horizontal haunches also serve as a stress distribution mechanism to prevent stress concentration on specific main reinforcement bars of the end RC. Stiffening ribs are provided on the RC beam side of the RC-S joint. This allows for the joint to accommodate cases where the S beam is joined eccentrically to the RC beam. This allows for hinge relocation design even for long-span beams, reducing damage to the column-beam joints in reinforced concrete structures. As a result, the size of the attached columns can also be reduced. By forming a hinge in the S-section, shear design for the central part of the beam becomes easier. [Explanation of Symbols]

[0019] 10 Building, 11 Column, 12 Slab, 13-15 Beam, 31 Reinforced concrete member, 32 Steel member, 33 Web section, 34a, 34b Flange section, 35 Boundary section, 36 Anchoring hole, 37a, 37b Rib section, 38 Anchoring means, 39 Hinge range, 41, 43 Fixed width section, 42 Haunch section, 44 Tapered section.

Claims

1. A reinforced concrete member provided on the column-beam joint side, Steel frame member located on the central side and Equipped with, The aforementioned steel frame member is A long, narrow, plate-shaped web section extending along the longitudinal direction, Extending along the longitudinal direction and connected in the width direction of the web portion, two elongated plate-shaped flange portions are substantially perpendicular to the web portion, A plate-shaped boundary portion is connected to the longitudinal ends of the web portion and flange portion, and is substantially perpendicular to the longitudinal direction, A plate-shaped rib portion is connected to the boundary portion on the side opposite to the web portion and flange portion, and is substantially parallel to the web portion. It has, The flange portion is The flange portion has a haunch portion located within a predetermined range from the end joined to the boundary portion, and a first constant width portion which constitutes the portion of the flange other than the haunch portion and has a substantially constant width, wherein the haunch portion is wider than the first constant width portion. The boundary portion is positioned in contact with the end face of the reinforced concrete member, The aforementioned haunch portion is, A second constant-width section with a width that is approximately constant, The haunch portion consists of a portion other than the second fixed width portion, and is further away from the boundary than the second fixed width portion, and the tapered portion is narrower than the second fixed width portion as it moves away from the boundary portion. Having, Composite beam.

2. The aforementioned steel frame member has two or more rib portions, At least two of the rib portions are arranged separately in a direction substantially perpendicular to the web portion. A composite beam according to claim 1.

3. The spacing between adjacent rib portions is greater than the width of the first fixed width portion and less than the width of the second fixed width portion. A composite beam according to claim 2.

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