JP2007291636A - Mixed-structure beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mixed-structure beam which can be surely and simply constructed without a connection between a steel-framed section and reinforcements of a reinforced concrete section. <P>SOLUTION: This mixed-structure beam A comprises the pair of reinforced concrete sections 2 which are protrusively provided inward from a pair of columns 1 of reinforced concrete construction, respectively, and the steel-framed section 3 which is framed in such a manner that the sides of both ends 3a and 3b are embedded in the reinforced concrete sections 2, respectively. Rod-shaped joints 4, which are protruded to the outside in the direction of an axis line O2 and integrally joined to the column 1, are provided on the sides of both the ends 3a and 3b of the steel-framed section 3, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mixed structure beam including a pair of reinforced concrete portions projecting inward from a pair of reinforced concrete columns and steel frame portions in which both end portions are respectively embedded in each reinforced concrete portion.

  Conventionally, a single-member beam structure of reinforced concrete structure or steel structure is used for the beam structure of a building. However, the beam structure made of steel has the advantage that the construction period for the frame is short, but on the other hand, the use of many expensive steel materials increases the cost, and the drawback is that the rigidity is lower than that of reinforced concrete. there were. On the other hand, a beam structure made of reinforced concrete has higher rigidity than steel structure and is excellent in economic efficiency, but has a problem that the construction period is prolonged.

  On the other hand, mixed structural beams combining steel (steel part) and reinforced concrete (reinforced concrete part) have been proposed. In this type of mixed structural beam, both ends of the beam joined to a pair of columns, respectively, Reinforced concrete is provided, and each of these reinforced concretes is provided with a steel frame by being embedded for a predetermined embedment length. Such a mixed structure beam is excellent in shear strength because reinforced concrete is provided on both ends of the beam structure where a large shearing force acts, and a highly rigid beam structure even if the cross-sectional size of the steel frame is reduced. Since it can be realized, it has the advantage that the amount of steel used can be reduced and the cost can be reduced. Furthermore, since it is not necessary to penetrate the steel frame into the column and join it, it is possible to easily construct the main bar of the column and to easily process the end of the steel frame.

In addition, for example, as disclosed in Patent Document 1, a starting end support plate is provided in a portion surrounded by a flange and a web at a position where the steel frame is embedded in the reinforced concrete, and each upper and lower flange of the steel frame at the position where the steel is embedded In some cases, a plurality of end bearing plates arranged symmetrically about the web axis (steel axis) are provided between the web and the web. In the case of having such a start-end bearing plate and end-end bearing plate, the stress transmission between the steel frame and the reinforced concrete can be transmitted through each bearing plate without joining the steel frame and the reinforced concrete reinforcement (main reinforcement). It can be performed smoothly and a beam structure with excellent rigidity can be constructed.
JP 2005-76379 A

  However, in the mixed structure beam having the above-mentioned start end support plate and end end support plate, the main end of the reinforced concrete and the shear reinforcement are placed so as to surround the end of the steel frame and the concrete is placed. The bearing plate and the end bearing plate impede the flow of concrete in the direction of the steel axis (material axis), and it requires a great deal of labor to embed the main reinforcement, shear reinforcement and steel frame in concrete concretely. There was a problem of causing deterioration.

  An object of this invention is to provide the mixed structure beam which can be constructed | assembled reliably and simply, without joining the steel frame part and the reinforcement of a reinforced concrete part in view of the said situation.

  In order to achieve the above object, the present invention provides the following means.

  The mixed structural beam of the present invention includes a pair of reinforced concrete portions projecting inward from a pair of reinforced concrete columns, and a steel frame portion in which both end portions are respectively embedded in the reinforced concrete portions and constructed. It is a structural beam, and the steel frame portion is provided with a rod-like joint portion that protrudes outward in the axial direction and is integrally joined to the column on each of both end sides.

  Further, in the mixed structure beam of the present invention, the steel part is an H-shaped steel, and the joining part has a rear end fixed to at least one of a pair of upper and lower flange parts of the steel part, and at least on the front end side in the protruding direction. It is desirable that the anchor bolt has a fixing portion for fixing to the pillar.

  Further, in the mixed structure beam of the present invention, the steel part is an H-shaped steel, and the joining part has a rear end fixed to at least one of a pair of upper and lower flange parts of the steel part, and at least on the front side in the protruding direction. It may be a reinforcing bar provided with a fixing portion fixed to the pillar.

  Further, in the mixed structure beam of the present invention, when the joint portion is an anchor bolt, a long nut is fixed to the flange portion, and the anchor bolt is provided by screwing a rear end side thereof to the long nut. It is more desirable.

  Furthermore, in the mixed structure beam of the present invention, an end plate having a plane perpendicular to the material axis is fixed to the end of the steel frame portion, and the anchor bolt is provided with its rear end side fixed to the end plate. It may be done.

  According to the mixed structural beam of the present invention, on both end sides of the steel frame portion, by providing rod-like joint portions such as anchor bolts and reinforcing bars that protrude outward in the axial direction of the material and are integrally joined to the columns, There is no risk of hindering the flow of concrete as in the case of the conventional bearing end plate and end bearing plate of the mixed structural beam, and the amount of steel used can be reduced and a highly rigid frame can be provided at low cost. Further, by integrally joining the steel frame portion and the column via this joint portion, it becomes possible to join each other reliably and simply, and this joint portion forms a yielding hinge portion. For this reason, it is possible to reduce the shearing force borne by the reinforced concrete part, and to perform an advantageous design against stress. Also, the designer decides whether to yield the steel part on one end facing the beam inside of the reinforced concrete part in advance and yielding part of the main reinforcement on the other end side located on the column side of the reinforced concrete part. Can be controlled.

  In addition, by providing a long nut in which the rear end side of the anchor bolt is screwed to the flange portion of the steel frame portion of the H-shaped steel, the anchor bolt can be easily attached at an arbitrary stage. If the anchor bolts are installed after the unattached steel frame is installed, the anchor bolt and the mixed structural beam can be installed easily without the anchor bolt interfering with the main bars of the column. It becomes possible to improve the property.

  In addition, when an end plate is provided at the end of the steel frame portion, the anchor bolt can be attached after the steel frame portion is installed, so that the same effect as described above can be obtained and the steel frame embedded in the reinforced concrete portion Since the end plate is provided only on the end side of the part, the flow of the concrete is hindered when the concrete of the reinforced concrete part is placed like the conventional mixed structure beam with the start end support plate and the end support plate. Never happen. Moreover, since it can receive stress also with an end plate with an anchor bolt, it becomes possible to further reduce the shear force which a reinforced concrete part bears.

  Hereinafter, with reference to FIG.1 and FIG.2, the mixed structure beam which concerns on one Embodiment of this invention is demonstrated.

  As shown in FIGS. 1 and 2, the mixed structural beam A according to the present embodiment is constructed between a pair of adjacent reinforced concrete columns 1 and connected to the side ends 1a of both the columns 1 respectively. A pair of reinforced concrete portions 2 projecting inward (center side between the pair of pillars 1) from 1a and the both end portions 3a and 3b sides are embedded in the reinforced concrete portion 2 with a predetermined embedment length. And a steel frame portion 3 made of H-shaped steel.

  The reinforced concrete part 2 includes a main reinforcing bar 2a extending along an axis (material axis) O1 in an upper part and a lower part in a cross-sectional view, and a shear reinforcing bar arranged around the upper and lower main reinforcing bars 2a at predetermined intervals in the direction of the axis O1. 2b. Each main reinforcing bar 2 a has one end extending inside the column 1 and is integrally joined to the column 1. Further, the plurality of shear reinforcement bars 2b arranged on the one end 2c side facing the inner side of the reinforced concrete part 2 in the axis O1 direction are arranged with a smaller interval in the axis O1 direction than other parts to form a concentrated reinforcement bar part 2d. is doing.

  On the other hand, the steel frame part 3 is formed with the length substantially the same as the space | interval of a pair of pillar 1, and the axial line (material axis | shaft) O2 is provided in the state arrange | positioned coaxially with the axis line O1 of the reinforced concrete part 2. Yes. Further, the steel frame part 3 is provided so that both ends 3a and 3b side embedded in the reinforced concrete part 2 are surrounded by the upper and lower main bars 2a and the shear reinforcement bars 2b of the reinforced concrete part 2. Further, the steel frame portion 3 has a rod-shaped anchor bolt provided with a fixing portion 4c that protrudes outward in the direction of the axis O2 on both ends 3a and 3b, and is formed by screwing a nut 4b on the tip 4a in the protruding direction. (Joint part) 4 is attached. In the present embodiment, the anchor bolt 4 has an axis parallel to the axis O2 of the steel frame part 3 on the surface facing the direction perpendicular to the axis O2 of both flange parts (upper flange part 3c, lower flange part 3d) of the steel frame part 3. The rear end side is screwed into the long nut 5 fixed in this state. Further, four anchor bolts 4 of the present embodiment are provided on both ends 3a, 3b side of the steel frame portion 3, and two anchor bolts 4 are fixed to each of the flange portions 3c, 3d on the end portions 3a, 3b side. Is provided. In the steel frame portion 3, each anchor bolt 4 is arranged inside the column 1 and is integrally joined to the column 1. The anchor bolt 4 is fixed by the fixing portion 4c so as to resist the pulling force from the pillar 1.

  A plurality of headed studs 6 protruding upward are fixed to the steel frame portion 3 at predetermined intervals in the direction of the axis O2 on the upper surface of the upper flange portion 4c exposed from the both reinforced concrete portions 2. And the concrete slab 7 laid on the upper flange part 4c of the steel frame part 3 is integrally joined with the steel frame part 3 through this stud 6 with a head.

  The mixed structural beam A configured as described above forms the steel frame portion 3 of a predetermined length in advance in a factory or a site yard, and at the stage where the long nut 5 is fixed to the flange portions 3c and 3d, While placing the main reinforcement 2a and the shear reinforcement 2b of the reinforced concrete part 2 so as to surround the both ends 3a and 3b, the mold is placed, and the concrete is placed in the mold to place both ends 3a of the steel frame 3; The reinforced concrete part 2 is integrally formed on the 3b side. At this time, since the steel plate portion 3 is not provided with the start end support plate or the end support plate, unlike the conventional mixed structure beam, the placed concrete is surely filled while flowing in the direction of the axis O2, The main reinforcement 2a, the shear reinforcement 2b, and the ends 3a and 3b of the steel frame 3 are embedded in the concrete in a solid state without any gaps. In this state, the opening portion of the long nut 5 is opened on the side surface of the reinforced concrete portion 2 facing outward in the axis O1 direction, and the main bar 2a extends outward from the side surface in the axis O1 direction.

  Next, when the mixed structural beam A is constructed, the end portion of the mixed structural beam A is placed on the column 1 that has been previously constructed up to the portion located at the lower end thereof. At this time, since the anchor bolt 4 is not attached to the end portion of the mixed structural beam A, it is easily installed without interfering with the main bar of the column 1 or the like. Then, after attaching the anchor bolts 4 to the long nuts 5, reinforcement of the columns 1 and slabs 7 is performed, and the concrete of the columns 1 and slabs 7 is placed. Thereby, the mixed structural beam A of the present embodiment is constructed between the pair of columns 1 with the main reinforcement 2a of the reinforced concrete portion 2 and the anchor bolts 4 joined to the columns 1. Further, the slab 7 is integrally joined to the mixed structural beam A through the headed stud 6. The mixed structural beam A thus constructed is joined to the column 1 without joining the steel frame portion 3 to the main reinforcement 2a of the reinforced concrete portion 2 and without penetrating the steel frame portion 3 into the column 1, Is easy.

  The mixed structural beam A constructed as described above is embedded in the reinforced concrete portion 2 of the steel frame portion 3 when the mixed structure beam A receives its own weight and the frame receives seismic force and shear force acts on the mixed structural beam A. Between the upper flange portion 3c of the steel frame portion 3 and the lower main reinforcing bar 2a of the reinforced concrete portion 2, a shearing stress in an oblique direction directed to the side where the steel frame portion 3 is pulled out from the reinforced concrete portion 2 is generated. On the other hand, in this mixed structural beam A, the anchor bolt 4 fixed to the column 1 receives a pulling force acting on the steel frame portion 3, that is, a part of the shear stress, and thereby the shear stress borne by the reinforced concrete portion 2 is increased. It will be reduced and the frame will be highly rigid. Further, since the steel frame part 3 is joined to the column 1 via the anchor bolt 4, a yield hinge can be formed at this joint part, and also from this point, the rigidity with reduced burden shearing force of the reinforced concrete part 2 is achieved. It becomes a high frame.

  Therefore, according to the mixed structure beam A of the present embodiment, the steel frame portion 3 is joined to the column 1 with the anchor bolts 4, so that the concrete bearing beam A and the end bearing pressure plate of the conventional mixed structure beam are made of concrete. There is no possibility of hindering the flow, and even if the cross-sectional size of the steel frame part 3 is reduced, a highly rigid frame can be provided, and the amount of steel used can be reduced and the cost can be reduced. Further, the mixed structural beam A (steel frame portion 3) and the column 1 can be reliably and simply joined by the anchor bolt 4, and the joint portion forms a yielding hinge portion, whereby the reinforced concrete portion 2 is obtained. Can reduce the shear force. Thereby, it becomes possible to apply to a frame having a large span, and it is possible to perform an advantageous design against stress. Further, when the steel frame part 3 on the one end 2c side facing the inner side of the axis O1 of the reinforced concrete part 2 is yielded in advance, a part of the main reinforcement 2a on the other end side located on the column 1 side of the reinforced concrete part 2 is preceded. The designer can control when yielding.

  Further, since the anchor bolt 4 can be attached by being screwed to the long nut 5 provided on the flange portions 3c and 3d of the steel frame portion 3 of the H-shaped steel, the anchor bolt 4 can be easily installed at an arbitrary stage. It is possible to improve the workability by installing the anchor bolt 4 after installing the steel frame portion 3 in a state where the bolt 4 is not attached.

  As mentioned above, although embodiment of the mixed structure beam A which concerns on this invention was described, this invention is not limited to said one Embodiment, It can change suitably in the range which does not deviate from the meaning. For example, in this embodiment, the long nuts 5 are provided on the flange portions 3c and 3d of the end portions 3a and 3b of the steel frame portion 3, and the rear end side is screwed to the long nut 5 so that the anchor bolt 4 is integrated with the steel frame portion 3. However, as shown in FIG. 3, the rear end side of the anchor bolt 4 may be welded and fixed to the flange portions 3c and 3d, and as shown in FIG. The end plate 8 may be fixed to the end portions 3a, 3b of the portion 3 by welding or the like, and the anchor bolt 4 may be provided by fixing the rear end side to the end plate 8 with a nut 8a. When the end plate 8 is provided only on the one end 3a (3b) side of the steel frame portion 3 embedded in the reinforced concrete portion 2 in this way, the mixed structure beam provided with the conventional start end support plate and end end support plate As described above, when the concrete of the reinforced concrete portion 2 is placed, the flow of the concrete is not hindered, and the end plate 8 together with the anchor bolt 4 can receive stress, so that the shearing force borne by the reinforced concrete portion 2 Can be further reduced.

  Further, the anchor bolt 4 is fixed to the end portions 3a and 3b of the steel frame portion 3 as a joint portion. However, as shown in FIG. 5, for example, a fixing bar (rebar) 10 such as a deformed rebar is fixed as the joint portion. Further, the fixing portion 10b may be formed by attaching a nut to the protruding direction front end 10a side. In the present embodiment, two anchor bolts 4 are provided at each of the both end portions 3a and 3b of the steel frame portion 3 and at each of the upper flange portion 3c and the lower flange portion 3d. The number of installations is not particularly limited as long as it is determined based on the design calculation. Further, at this time, the anchor bolt 4 may be attached only to the upper flange portion 3c, for example. In addition, the anchor bolt 4 is fixed to the surface facing the outer side perpendicular to the axis O2 of the upper flange portion 3c and the lower flange portion 3d. For example, the anchor bolt 4 is substantially orthogonal to the axis O2 of the upper flange portion 3c or the lower flange portion 3c. Then, the anchor bolt 4 may be fixed to the surface facing inward.

  In the present embodiment, the tip 4a side of the anchor bolt 4 is fixed inside the column 1. However, the anchor bolt 4 of the mixed structure beam A penetrates the column 1 as shown in FIG. Even if the tip of the anchor bolt 4 is fixed to the end portions 3a and 3b of the steel frame portion 3 of the other mixed structure beam A that is arranged so as to face the mixed structure beam A with the column 1 interposed therebetween. Good.

  Furthermore, although the pillar 1 to which the mixed structural beam A of the present embodiment is joined is formed by on-site construction, it may be joined to a precast pillar.

It is a figure which shows the mixed structure beam which concerns on one Embodiment of this invention. It is a perspective view which shows the steel beam of the mixed structure beam which concerns on one Embodiment of this invention, and the anchor bolt fixed to this steel beam. It is a perspective view of the steel beam shown as a modification of the mixed structure beam which concerns on one Embodiment of this invention, and the anchor bolt fixed to this steel beam. It is a perspective view of the steel beam shown as a modification of the mixed structure beam which concerns on one Embodiment of this invention, and the anchor bolt fixed to this steel beam. It is a perspective view of the steel beam shown as a modification of the mixed structure beam which concerns on one Embodiment of this invention, and the fixed reinforcement fixed to this steel beam. It is a figure which shows the steel beam of the modification of the mixed structure beam which concerns on one Embodiment of this invention, and the anchor bolt fixed to this steel beam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Column 1a Side surface 2 Reinforced concrete part 2a Main reinforcement 2b Shear reinforcement 3 Steel part 3a End part 3b End part 3c Flange part (upper flange part)
3d flange (lower flange)
4 Anchor bolt (joint)
4a Tip 4b Nut 4c Fixing part 5 Long nut 6 Head stud 7 Slab 8 End plate 10 Fixing bar (joint part)
10a Tip 10b Fixing part A Mixed structural beam O1 Reinforced concrete part axis O2 Steel part axis

Claims (5)

A mixed structural beam comprising a pair of reinforced concrete portions projecting inwardly from a pair of reinforced concrete columns, and steel frame portions constructed by embedding both ends on the reinforced concrete portions,
The mixed structure beam, wherein the steel frame portion is provided with a rod-like joint portion that protrudes outward in the axial direction and is integrally joined to the column on each of both end sides. The mixed structural beam according to claim 1,
The steel frame portion is an H-shaped steel, and the joint portion includes a fixing portion that has a rear end fixed to at least one of a pair of upper and lower flange portions of the steel frame portion and is fixed to the column at least on the front end side in the protruding direction. Mixed structural beam characterized by anchor bolts. The mixed structural beam according to claim 1,
The steel frame portion is an H-shaped steel, and the joint portion includes a fixing portion that has a rear end fixed to at least one of a pair of upper and lower flange portions of the steel frame portion and is fixed to the column at least on the front end side in the protruding direction. Mixed structural beam characterized by being a reinforcing bar. The mixed structural beam according to claim 2,
A mixed structural beam, wherein a long nut is fixed to the flange portion, and the anchor bolt is provided with a rear end screwed to the long nut. The mixed structural beam according to claim 2,
An end plate having a plane perpendicular to the material axis is fixed to an end portion of the steel frame portion, and the anchor bolt is provided with a rear end side fixed to the end plate. .

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