JP2010255341A - Beam member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a beam member for increasing attachment strength on a concrete placing joint surface between a half-precast beam member and post-cast concrete, and suppressing a shear failure. <P>SOLUTION: A composite beam 16 of a building 10 is formed of the beam member 20 and a slab concrete 22. The beam member 20 has the half-precast beam member 21 having the main reinforcement 27 which is exposed, and a reinforcing bar 24 as a simple substance arranged in a manner of crossing the concrete placing joint surface M of the half-precast beam member 21 a plurality of times. Since the reinforcing bar 24 as a simple substance crosses the concrete placing joint surface M of the half-precast beam member 21 a plurality of times, the attachment strength of the half-precast beam member 21 and the post-cast concrete is increased. Further, the shear failure on the concrete placing joint surface M can be suppressed since the shear force transmission of the half-precast beam member 21 and the post-cast concrete is improved because of the existence of the reinforcing bar 24. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a beam member using half precast.

  2. Description of the Related Art Conventionally, there is a beam member constructed using a method in which slab concrete is post-placed on top of a half precast beam member (see, for example, Patent Document 1).

  The beam member of Patent Document 1 compares the half height of the entire beam member with the height of the slab concrete, and classifies the case to determine the design standard strength of the concrete of the half precast beam member and the design standard strength of the slab concrete. By using this to calculate the shear strength of the beam member, excessive shear reinforcement is suppressed.

  However, Patent Document 1 does not disclose means for increasing the adhesion strength between the half precast beam member and the slab concrete on the concrete connection surface.

JP 2006-225894 A

  An object of this invention is to obtain the beam member which can suppress the shear failure while increasing the adhesion strength in the concrete joint surface of a half precast beam member and post-cast concrete.

  The beam member according to claim 1 of the present invention is embedded in one or more half precast beam members with exposed upper reinforcing bars and one or more in the direction intersecting the axial direction of the half precast beam members, and the concrete of the half precast beam members A single reinforcing bar disposed across the joining surface a plurality of times.

  According to the above configuration, since the reinforcing bars straddle a plurality of locations on the concrete connection surface of the half precast beam member, the adhesion strength between the half precast beam member and the post-cast concrete can be increased. Furthermore, since there is a reinforcing bar, the shear force transmission between the half precast beam member and the post-cast concrete is improved, so that it is possible to suppress shear failure on the concrete joint surface.

  In the beam member according to claim 2 of the present invention, the reinforcing bars are reinforcing bars formed in a spiral shape. According to this configuration, the concrete inside the vortex is restrained by the spiral reinforcing bars, so that the concrete strength of the beam member at the time of bending yield can be increased. Further, since the reinforcing bars can be positioned by fixing both end portions of the reinforcing bars, the bar arrangement work is facilitated.

  In the beam member according to claim 3 of the present invention, the reinforcing bars are formed in a square shape when viewed in the direction of the central axis of the spiral. According to this configuration, since the reinforcing bar is square, the upper side of the reinforcing bar is flat. As a result, when the upper reinforcing bars are further arranged, the upper reinforcing bars can be attached to the upper side of the reinforcing bars, and the arrangement work of the upper reinforcing bars becomes easy.

  In the beam member according to claim 4 of the present invention, the reinforcing bar is disposed across both the assumed splitting surface where the splitting is assumed in the vicinity of the upper reinforcing bar when an external force is applied and the concrete connecting surface. ing. According to this configuration, the reinforcing bar and the post-cast concrete are integrated before and after the assumed split surface. Thereby, it is possible to suppress the splitting of the post-cast concrete near the upper rebar.

  In the beam member according to claim 5 of the present invention, the reinforcing bars are provided only at both axial ends of the half precast beam member. According to this configuration, the reinforcing bars are provided only at both ends of the beam member where the shear failure is likely to occur on the concrete connection surface, so that the cost can be reduced as compared with the case where the reinforcing bars are provided on the entire beam member.

  Since the present invention is configured as described above, it is possible to increase the adhesion strength of the half precast beam member and the post-cast concrete on the concrete joint surface and to suppress shear fracture.

(A) It is explanatory drawing of the building which concerns on 1st Embodiment of this invention. (B) It is a top view in the state except the slab of the composite beam which concerns on 1st Embodiment of this invention. (A), (b) It is a fragmentary sectional view of the construction direction or width direction of the composite beam which concerns on 1st Embodiment of this invention. (A)-(c) It is process drawing which shows the construction procedure of the composite beam which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the deformation | transformation state of a composite beam when external force acts on the building which concerns on 1st Embodiment of this invention. (A) It is sectional drawing which shows the other 1st Example of the composite beam which concerns on 1st Embodiment of this invention. (B) It is a top view which shows the other 2nd Example of the composite beam which concerns on 1st Embodiment of this invention. (A), (b) It is a fragmentary sectional view of the construction direction or width direction of the composite beam which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the other Example of the composite beam which concerns on 2nd Embodiment of this invention. (A), (b) It is the top view of the composite beam which concerns on 3rd Embodiment of this invention, or the fragmentary sectional view of the width direction. (A) It is a schematic diagram which shows the assumption split surface in the composite beam which concerns on 3rd Embodiment of this invention. (B) It is a schematic diagram which shows a split state when external force acts on the composite beam which concerns on 3rd Embodiment of this invention. (A), (b) It is the top view of the composite beam which concerns on 4th Embodiment of this invention, or the fragmentary sectional view of the width direction. (A) It is a schematic diagram which shows the assumption split surface in the composite beam which concerns on 4th Embodiment of this invention. (B) It is a schematic diagram which shows the split state when external force acts on the composite beam which concerns on 4th Embodiment of this invention.

  A beam member according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1A shows a part of a building 10 constructed on the ground 12. The building 10 is composed of a plurality of columns 14 erected on the ground 12 and a plurality of composite beams 16 installed on the columns 14. The composite beam 16 includes a beam member 20 that is half precast and a slab concrete 22 formed on the beam member 20. In the slab concrete 22, the concrete strength at the time of bending yield is less than the concrete strength of the beam member 20. In the following, illustration of the main and distribution bars of the slab concrete 22 and the small beams installed on the composite beam 16 is omitted.

  As shown in FIGS. 1B and 2A, the beam member 20 is embedded in a concrete half precast beam member 21 and both ends of the half precast beam member 21 in the axial direction (arrow X direction). In addition, the reinforcing member 24 has a single reinforcing bar 24 that is disposed across a concrete joining surface M, which is an interface between the beam member 20 and the slab concrete 22, a plurality of times.

  As shown in FIGS. 2A and 2B, the half precast beam member 21 includes a plurality of main bars 25 embedded along the axial direction of the composite beam 16, and surrounds the plurality of main bars 25 and the composite beam 16. It has a U-shaped stirrup 26 which is arranged at an interval in the axial direction. In addition, although the reinforcing bar used for each part of the composite beam 16 is a deformed reinforcing bar, when illustrated in the following description, it is displayed with round steel bars.

  Both ends of the stirrup 26 are bent into a hook shape and protrude upward from the concrete joining surface M, which is the upper surface of the half precast beam member 21, and are slab concrete 22 along the axial direction of the half precast beam member 21. A part of the plurality of main muscles 27 buried in the body is fastened. In addition, a width stop line 28, which is substantially U-shaped as a whole and is formed in a hook shape at one end, is fastened together with the main line 27 at both ends of the ribbed line 26.

  The reinforcing bar 24 is a circular (spiral) reinforcing bar having a radius R as seen in the axial direction of the half precast beam member 21 (see FIG. 2B), and the length of the reinforcing bar 24 in the arrow X direction. L is D ≦ L ≦ 1.5D, where D is the length of the composite beam 16. The vertical embedded length d1 and the exposed length d2 of the reinforcing bars 24 in the half precast beam member 21 are appropriately set according to the required adhesion strength of the half precast beam member 21 and the slab concrete 22, As an example, the embedment length d1 = exposure length d2 = radius R is set.

  Further, the reinforcing bar 24 is disposed in a rectangular cross-sectional area surrounded by the ribs 26 and the width stop bars 28 when viewed in the axial direction of the half precast beam member 21, and the upper part (arc) of the reinforcing bar 24. The main reinforcement 27 of the slab concrete 22 is tightly connected to the top of the slab.

  Next, the construction procedure of the composite beam 16 will be described.

  As shown in FIG. 3A, the main bar 25, the stirrup bar 26, and the reinforcing bar 24 are disposed in a mold 32 having a rectangular parallelepiped shape and an open upper surface. The main bar 25 and the ribbed bar 26 are positioned by being supported by a pair of side walls (not shown) of the mold 32 in a state where the main bar 25 and the rib bar 26 are tightly coupled. Further, the reinforcing bars 24 are positioned by fixing both end portions (upper end portions) of the exposed portions with fixing members (not shown). Here, the reinforcing bar 24 has a spiral shape although it is a single body, and can be positioned as a whole by fixing both ends. Therefore, the reinforcing bars 24 are arranged in comparison with those in which the reinforcing bars (reinforcing bars) are arranged one by one. Work becomes easy. Subsequently, the concrete C is cast to a height at which a part of the ribs 26 and the reinforcing bars 24 are exposed, and after curing, the formwork 32 is removed to form the beam member 20.

  Subsequently, as shown in FIG. 3B, both end portions of the main bar 25 are joined to the column 14, and the beam member 20 is installed on the two columns 14. On the beam member 20, a plurality of main bars 27 extending in the axial direction of the beam member 20 are arranged in parallel in the width direction of the beam member 20, and width stop bars 28 are arranged in accordance with the ribs 26. Here, the two main bars 27 on the outer side in the width direction of the beam member 20 are respectively fastened to the hook-shaped portions of the stirrups 26, and the two main bars 27 on the inner side in the width direction are connected to the reinforcing bars 24 and the width stop bars 28. To do.

  Subsequently, as shown in FIG. 3C, the formwork 34 of the slab concrete 22 is arranged in accordance with the height of the concrete joining surface M of the beam member 20, and the reinforcing bars and main reinforcing bars ( (Not shown) is placed and concrete is placed in the mold 34. Thereby, the reinforcing bar 24 is embedded and the slab concrete 22 and the composite beam 16 are constructed.

  Next, the operation of the first embodiment of the present invention will be described.

  FIG. 4 is a schematic diagram showing a state in which a horizontal external force F acts on the building 10 during an earthquake, the column 14 is tilted, and the composite beam 16 is deformed in an inverse symmetry. Here, in the composite beam 16, the reinforcing bars 24 straddle a plurality of locations on the concrete joint surface M of the beam member 20, and the adhesion of the concrete and the reinforcing bars 24 on the beam member 20 and the slab concrete 22 The adhesion strength between the beam member 20 and the slab concrete 22 is increased by the adhesion between the concrete and the reinforcing bars 24. Furthermore, in the composite beam 16, since the reinforcing bars 24 are embedded, the shear force transmission between the beam member 20 and the slab concrete 22 is improved as compared with the case where the reinforcing bars 24 are not provided. With these actions, the composite beam 16 can suppress shear fracture at the concrete connection surface M.

  Further, in the composite beam 16, the reinforcing bar 24 is a reinforcing bar formed in a spiral shape. Therefore, the concrete of the relatively high-strength beam member 20 inside the vortex of the reinforcing bar 24 and the relatively low-strength slab concrete. 22 concretes are restrained. Thereby, since the strength of the slab concrete 22 can be made equal to the concrete strength of the beam member 20, it is possible to suppress the destruction of the composite beam 16 when the composite beam 16 (beam member 20) is bent and yielded.

  Further, in the composite beam 16, the reinforcing bars 24 are provided only at both ends of the beam member 20 where the shear failure on the concrete joining surface M is likely to occur. Therefore, the cost is lower than that in which the reinforcing bars 24 are provided on the entire beam member 20. Can be realized.

  Next, another example of the first embodiment of the beam member of the present invention will be described with reference to the drawings. Note that the same reference numerals as those in the first embodiment are given to the members that are basically the same as those in the first embodiment described above, and the description thereof is omitted.

  FIG. 5A shows a composite beam 36 as another first example of the beam member 20 of the first embodiment (see FIG. 2B). The composite beam 36 includes a beam member 30 that is half precast and a slab concrete 22 formed on the beam member 30.

  The beam member 30 includes a half precast beam member 31 made of concrete, and reinforcing bars 38A and 38B that are embedded side by side in the direction (width direction) intersecting the axial direction at both axial ends of the half precast beam member 31. have. The half precast beam member 31 includes a plurality of main bars 25 embedded along the axial direction of the composite beam 36, and stirrups 26 that surround the plurality of main bars 25 and are spaced apart from each other in the axial direction of the composite beam 36. have.

  Both ends of the stirrup 26 protrude upward from the concrete joint surface M, which is the upper surface of the half precast beam member 31, and a plurality of slab concretes 22 are embedded along the axial direction of the half precast beam member 31. A part of the main muscle 27 is tightened. In addition, a width stop line 28 and a main line 27 are fastened to both ends of the ribbed line 26.

  The reinforcing bars 38A, 38B are circular spiral reinforcing bars when viewed in the axial direction of the half precast beam member 31, and are disposed across the concrete joining surface M a plurality of times. The axial lengths of the reinforcing bars 38A and 38B are 1.0 to 1.5 times the length of the beam of the composite beam 36. Further, the reinforcing bars 38A and 38B are disposed in a rectangular cross-sectional area surrounded by the ribs 26 and the width stopper bars 28 when viewed in the axial direction of the half precast beam member 31, and the reinforcing bars 38A and 38B. A main bar 27 of the slab concrete 22 is fastened to the upper part (the top of the arc) of the slab.

  Here, since the two reinforcing bars 38A and 38B are embedded in the beam member 30 in the width direction of the half precast beam member 31, the amount of reinforcing bars straddling the concrete connecting surface M increases, and the concrete connecting surface With M, the adhesion strength between the half precast beam member 31 and the slab concrete 22 can be increased.

  On the other hand, FIG. 5B shows a composite beam 42 as another second example of the beam member 20 of the first embodiment (see FIG. 2B). The composite beam 42 includes a beam member 40 that is half precast and the slab concrete 22 formed on the beam member 40.

  The beam member 40 includes a half precast beam member 41 made of concrete, and a reinforcing bar 44 embedded in the central portion in the axial direction of the half precast beam member 41. The half precast beam member 41 surrounds the plurality of main bars 25 (not shown in FIG. 5B) embedded along the axial direction of the composite beam 42, and is spaced apart in the axial direction of the composite beam 42. And the ribs 26 arranged with a gap.

  Both end portions of the stirrup 26 protrude upward from the concrete joining surface M, which is the upper surface of the half precast beam member 41, and some of the plurality of main bars of the slab concrete 22 are tightly connected. In addition, width-reducing bars (not shown) are provided at both ends of the ribbed bars 26 and are fastened together with a plurality of main bars 27 (see FIG. 2B) of the slab concrete 22.

  The reinforcing bar 44 is a circular spiral reinforcing bar as viewed in the axial direction of the half precast beam member 41, and is disposed across the concrete joint surface M a plurality of times. Further, the reinforcing bar 44 is disposed in a rectangular cross-sectional area surrounded by the ribs 26 and the width-stopping bars when viewed in the axial direction of the half precast beam member 41, and the upper part of the reinforcing bar 44 (arc-shaped). The main bar of the slab concrete 22 is fastened to the top part.

  Here, since the reinforcing member 44 is embedded in the axial center part of the beam member 40 and the adhesion strength between the half precast beam member 41 and the slab concrete 22 is increased in the axial center part, an external force acts. Thus, in the failure mode in which the shear failure increases at the axially central portion of the beam member 40, the shear failure of the beam member 40 can be suppressed.

  Next, 2nd Embodiment of the beam member of this invention is described based on drawing. Note that the same reference numerals as those in the first embodiment are given to the members that are basically the same as those in the first embodiment described above, and the description thereof is omitted.

  FIGS. 6A and 6B show a composite beam 52 provided in place of the composite beam 16 (see FIG. 1) of the building 10 of the first embodiment. The composite beam 52 includes a beam member 50 that is half precast and a slab concrete 22 formed on the beam member 50.

  The beam member 50 is embedded in a concrete half precast beam member 51 and both ends of the half precast beam member 51 in the axial direction (arrow X direction), and is a concrete connection surface that is an interface between the beam member 50 and the slab concrete 22. And a single reinforcing bar 54 disposed across the M multiple times.

  The half precast beam member 51 includes a plurality of main bars 25 embedded along the axial direction of the composite beam 52, and ribs 26 surrounding the plurality of main bars 25 and arranged at intervals in the axial direction of the composite beam 52. have. Both ends of the stirrup 26 protrude upward from the concrete joint surface M of the half precast beam member 51, and a plurality of main bars 27 embedded along the axial direction of the half precast beam member 51 with the slab concrete 22. Some are tightly coupled. In addition, a width stop line 28 and a main line 27 are fastened to both ends of the ribbed line 26.

  The reinforcing bar 54 is a spiral reinforcing bar having a rectangular shape when viewed in the axial direction of the half precast beam member 51 (the direction of the center axis of the spiral), and the length of the reinforcing bar 54 in the direction of the arrow X is 1 of the beam length of the composite beam 16. 0.0 times to 1.5 times. The vertical embedding length and the exposed length of the reinforcing bars 54 in the half precast beam member 51 are set as appropriate according to the required adhesion strength of the half precast beam member 51 and the slab concrete 22, but here one example As such, the embedment length is set to be the exposure length.

  Further, the reinforcing bars 54 are disposed in a rectangular cross-sectional area surrounded by the ribs 26 and the width stopper bars 28 when viewed in the axial direction of the half precast beam member 51. The main reinforcement 27 of the slab concrete 22 is tightly connected. In addition, since the construction procedure of the composite beam 52 is the same as the construction procedure of the composite beam 16 of the first embodiment (see FIGS. 3A to 3C), the description thereof is omitted.

  Next, the operation of the second embodiment of the present invention will be described.

  6 (a) and 6 (b), when a horizontal external force acts during an earthquake and the column 14 is tilted and the composite beam 52 is deformed in an inverse symmetry, the composite beam 52 is subjected to the concrete joining of the beam member 50. The reinforcing bars 54 straddle a plurality of locations on the surface M alone, and the beam member 50 and the slab are bonded to each other by the adhesion action of the concrete and the reinforcement bars 54 on the beam member 50 and the adhesion action of the concrete and the reinforcement bar 54 on the slab concrete 22. The adhesion strength with the concrete 22 is increasing. Furthermore, in the composite beam 52, the reinforcement reinforcement 54 is embedded, so that the shear force transmission between the beam member 50 and the slab concrete 22 is improved as compared with the case where the reinforcement reinforcement 54 is not provided. With these actions, the composite beam 52 can suppress shear fracture at the concrete connection surface M.

  Further, in the composite beam 52, the reinforcing bars 54 are spiral reinforcing bars, so that the concrete of the relatively high-strength beam member 50 inside the vortex of the reinforcing bars 54 and the relatively low-strength slab concrete are provided. 22 concretes are restrained. As a result, the strength of the slab concrete 22 can be made equal to the concrete strength of the beam member 50, so that the concrete strength of the composite beam 52 (beam member 50) at the time of bending yield increases, and the destruction of the composite beam 52 is suppressed. be able to.

  Further, in the composite beam 52, since the reinforcing bars 54 are formed in a square shape when viewed in the direction of the center axis of the spiral, the upper side of the reinforcing bars 54 becomes flat. Thereby, when the main reinforcement 27 of the slab concrete 22 is further arranged, the main reinforcement 27 can be attached to the upper side of the reinforcing reinforcement 54, and the arrangement | positioning operation | work of the main reinforcement 27 becomes easy. Further, in the composite beam 52, the reinforcing bars 54 are provided only at both ends of the beam member 50 where the shear failure at the concrete joining surface M is likely to occur. Therefore, the cost is lower than that in which the reinforcing bars 54 are provided in the entire beam member 50. Can be realized.

  Next, another example of the second embodiment of the beam member of the present invention will be described with reference to the drawings. Note that the same reference numerals as those in the second embodiment are given to members that are basically the same as those in the second embodiment described above, and description thereof is omitted.

  FIG. 7 shows a composite beam 62 as another example of the beam member 50 (see FIGS. 6A and 6B) of the second embodiment. The composite beam 62 includes a beam member 60 that is half precast and the slab concrete 22 formed on the beam member 60.

  The beam member 60 is embedded in the concrete half precast beam member 61 and both ends of the half precast beam member 61 in the axial direction, and straddles the concrete connection surface M that is an interface between the beam member 60 and the slab concrete 22 a plurality of times. And a single reinforcing bar 64 arranged in the above. The half precast beam member 61 includes a plurality of main bars 25 embedded along the axial direction of the composite beam 62, and ribs 26 surrounding the plurality of main bars 25 and arranged at intervals in the axial direction of the composite beam 62. have.

  Both ends of the stirrup 26 protrude upward from the concrete joining surface M, and a part of the plurality of main bars 27 embedded along the axial direction of the half precast beam member 61 in the slab concrete 22 is tightly coupled. Yes. In addition, a width stop line 28 and a main line 27 are fastened to both ends of the ribbed line 26.

  The reinforcing bar 64 is a spiral reinforcing bar having a rectangular shape when viewed in the axial direction of the half precast beam member 61, and the axial length of the reinforcing bar 64 is 1.0 to 1.5 times the beam length of the composite beam 62. It has doubled. The embedded length and the exposed length of the reinforcing bars 64 in the half precast beam member 61 are set so that the embedded length = the exposed length. Further, the reinforcing bar 64 is located in a rectangular cross-sectional area surrounded by the stirrups 26 and the width stop bars 28 and the upper side is substantially the same height as the width stop bars 28 when viewed in the axial direction of the half precast beam member 61. The main bar 27 of the slab concrete 22 is fastened to the upper side of the reinforcing bar 64.

  Here, in the beam member 60, the main bar 27 is disposed in a region where the concrete is constrained by the reinforcing bar 64, and the reinforcing strength of the main bar 27 is increased by the reinforcing bar 64, and the composite beam 62 (the beam member 60) is attached. Strength increases.

  Next, 3rd Embodiment of the beam member of this invention is described based on drawing. Note that the same reference numerals as those in the first embodiment are given to the members that are basically the same as those in the first embodiment described above, and the description thereof is omitted.

  FIGS. 8A and 8B show a composite beam 72 provided in place of the composite beam 16 (see FIG. 1) of the building 10 of the first embodiment. The composite beam 72 includes a beam member 70 that is half precast and the slab concrete 22 formed on the beam member 70.

  The beam member 70 includes a half precast beam member 71 made of concrete, and a plurality of reinforcing bars 74 embedded at intervals in both end portions in the axial direction (arrow X direction) of the half precast beam member 71.

  The half precast beam member 71 includes a plurality of main bars 25 embedded along the axial direction of the composite beam 72, and stirrups 26 that surround the plurality of main bars 25 and are arranged at intervals in the axial direction of the composite beam 72. have. Both ends of the stirrup 26 protrude upward from the concrete connection surface M of the half precast beam member 71, and a plurality of main bars 27 embedded along the axial direction of the half precast beam member 71 in the slab concrete 22. Some are tightly coupled. In addition, a width stop line 28 and a main line 27 are fastened to both ends of the ribbed line 26.

  The reinforcing bar 74 is a reinforcing bar formed in a substantially isosceles triangular shape when viewed in the axial direction of the half precast beam member 71, and the bottom corner portion has an R shape. In the following description, in order to clarify the arrangement of the reinforcing bars 74, it is assumed that the reinforcing bars 74 are isosceles triangles and the base angle portion is an acute angle. The reinforcing bar 74 has a vertex A as a point A, a base angle as a point B, and a point C. The line BC is parallel to the concrete connecting surface M and the point A is lower than the line BC. The line segment AB and the line segment AC straddle the concrete joint surface M.

  Here, as shown to Fig.9 (a), in the slab concrete 22, the assumed split surface S which passes along the main reinforcement 27 is set. In addition, the assumed splitting surface S passes through the side split fracture, which is a split that passes through all the main bars 27 in the horizontal direction, and the main bars 27 that are arranged on the outermost side as the fracture mode of the adhesion split fracture in the slab concrete 22. It is set by determining which corner split fracture, which is a split, occurs.

  In slab concrete 22, whether side split failure or corner split failure occurs can be determined using equations (1) to (3) (reference document “Toughness-Guaranteed Seismic Design Guideline for Reinforced Concrete Buildings”. , Architectural Institute of Japan, 19999.8). In the equations (1) to (3), bi is the split line length ratio, bsi is the split line length ratio in the side split fracture, bci is the split line length ratio in the corner split fracture, and b is the beam member. 70, N is the number of main bars 27 (four in this embodiment), dcs is the cover thickness from the center to the side of the main bar 27, dct is the cover thickness from the center of the main bar 27 to the upper surface, and db is the main bar 27 diameter.

  Here, bsi and bci are obtained by using the equations (2) and (3), and these are compared by the equation (1), and the smaller one is selected. Can be determined. In this embodiment, as shown in the figure, it is determined that a corner split fracture occurs, and an assumed split surface S in an oblique direction is set.

  In the vicinity of the points B and C, the reinforcing bars 74 are arranged such that the line segment AB, the line segment BC, and the line segment AC all straddle the assumed splitting surface S. Therefore, the reinforcing bar 74 is disposed across both the concrete joint surface M and the assumed split surface S.

  As shown in FIG. 8A, the installation range of the reinforcing bars 74 is a range of 1.0 to 1.5 times the length of the beam from the both ends in the axial direction of the composite beam 72 toward the center. It has become. The vertical embedding length and the exposed length of the reinforcing bars 74 in the half precast beam member 71 are appropriately set according to the required adhesion strength of the half precast beam member 71 and the slab concrete 22, but here an example As such, the embedment length is set to be the exposure length. Moreover, since the construction procedure of the composite beam 72 is the same as the construction procedure of the composite beam 16 of the first embodiment (see FIGS. 3A to 3C), description thereof is omitted.

  Next, the operation of the third embodiment of the present invention will be described.

  In FIG. 9B, when a horizontal external force acts during an earthquake and the column 14 is tilted and the composite beam 72 is deformed in an inverse symmetry, the composite beam 72 reinforces the concrete joint surface M of the beam member 70. The reinforcement member 74 straddles a plurality of locations as a single body, and the beam member 70 and the slab concrete 22 are bonded to each other by the adhesion action of the concrete and the reinforcement reinforcement 74 on the beam member 70 and the adhesion action of the concrete and the reinforcement reinforcement 74 on the slab concrete 22. Adhesion strength is increasing. Furthermore, in the composite beam 72, since the reinforcing bar 74 is embedded, the shear force transmission between the beam member 70 and the slab concrete 22 is improved as compared with the case where the reinforcing bar 74 is not provided. By these actions, the composite beam 72 can suppress the shear fracture at the concrete connection surface M.

  In the composite beam 72, the reinforcing bar 74 has a closed shape of a substantially isosceles triangle. Therefore, the concrete of the relatively high-strength beam member 70 inside the reinforcing bar 74 and the relatively low-strength slab are provided. The concrete 22 is constrained with the concrete. Thereby, since the strength of the slab concrete 22 can be made equal to the concrete strength of the beam member 70, the concrete strength at the time of bending yield of the composite beam 72 (beam member 70) increases, and the destruction of the composite beam 72 is suppressed. be able to.

  Furthermore, in the composite beam 72, the reinforcing bar 74 having bending rigidity and the concrete of the slab concrete 22 are attached before and after the assumed splitting surface S, so that the reinforcing bar 74 resists the shearing force, thereby reducing the slab. It is possible to suppress the occurrence of splitting (corner split fracture in the present embodiment) in the concrete near the main reinforcement 27 of the concrete 22. In addition, since the reinforcing bars 74 are provided only at both ends of the beam member 70 where the shear failure at the concrete joining surface M is likely to occur, the cost can be reduced as compared with the case where the reinforcing bars 74 are provided on the entire beam member 70. .

  Next, 4th Embodiment of the beam member of this invention is described based on drawing. Note that the same reference numerals as those in the first embodiment are given to the members that are basically the same as those in the first embodiment described above, and the description thereof is omitted.

  FIGS. 10A and 10B show a composite beam 82 provided in place of the composite beam 16 (see FIG. 1) of the building 10 of the first embodiment. The composite beam 82 includes a beam member 80 that is half precast and the slab concrete 22 formed on the beam member 80.

  The beam member 80 includes a half precast beam member 81 made of concrete and a plurality of reinforcing bars 84 embedded in the both ends in the axial direction (arrow X direction) of the half precast beam member 81 at intervals.

  The half precast beam member 81 includes a plurality of main bars 25 embedded along the axial direction of the composite beam 82, and ribs 26 surrounding the plurality of main bars 25 and arranged at intervals in the axial direction of the composite beam 82. have. Both ends of the stirrup 26 protrude upward from the concrete joint surface M of the half precast beam member 81, and a plurality of main bars 27 embedded along the axial direction of the half precast beam member 81 with the slab concrete 22. Some are tightly coupled. In addition, a width stop line 28 and a main line 27 are fastened to both ends of the ribbed line 26.

  The reinforcing bars 84 extend in the horizontal direction from the V-shaped reinforcing portion 84A (line segment FE + line segment FG) as viewed in the axial direction of the half precast beam member 81 and outward from both ends of the reinforcing portion 84A. The reinforcing bar is composed of a fixing unit 84B (line segment DE) and a fixing unit 84C (line segment GH). The reinforcing bars 84 are arranged so that the points D, E, G, and H are linear, and the vertex F is located below the points D, E, G, and H.

  Here, as shown in FIG. 11A, in the reinforcing bar 84, the line segment FE and the line segment FG of the reinforcing portion 84A straddle the concrete joint surface M and the assumed split surface S. Note that the assumed splitting surface S is set by determining the fracture mode based on the equations (1) to (3) as in the composite beam 72 of the third embodiment. In this embodiment, the corner split fracture is performed. Is selected.

  As shown in FIG. 10A, the installation range of the reinforcing bars 84 is a range of 1.0 to 1.5 times the length of the beam from the both ends in the axial direction of the composite beam 82 toward the center. It has become. The vertical embedding length and the exposed length of the reinforcing bars 84 in the half precast beam member 81 are appropriately set according to the required adhesion strength of the half precast beam member 81 and the slab concrete 22, but here an example As such, the embedment length is smaller than the exposure length. Moreover, since the construction procedure of the composite beam 82 is the same as the construction procedure of the composite beam 16 of the first embodiment (see FIGS. 3A to 3C), description thereof is omitted.

  Next, the operation of the fourth exemplary embodiment of the present invention will be described.

  In FIG. 11B, when a horizontal external force acts during an earthquake and the column 14 is tilted and the composite beam 82 is deformed in an antisymmetric shape, the composite beam 82 reinforces the concrete connection surface M of the beam member 80. The bars 84 straddle a plurality of locations as a single unit, and the beam member 80 and the slab concrete 22 are bonded by the adhesion action of the concrete and the reinforcement bars 84 on the beam member 80 and the adhesion action of the concrete and the reinforcement bars 84 on the slab concrete 22. Adhesion strength is increasing. Furthermore, in the composite beam 82, since the reinforcing bar 84 is embedded, the shear force transmission between the beam member 80 and the slab concrete 22 is improved as compared with the case where the reinforcing bar 84 is not provided. By these actions, the composite beam 82 can suppress the shear fracture at the concrete joint surface M.

  Further, in the composite beam 82, the reinforcing bar 84 having bending rigidity and the concrete of the slab concrete 22 are attached before and after the assumed splitting surface S, so that the reinforcing bar 84 is resistant to the shearing force, so that the slab It is possible to suppress the occurrence of splitting (corner split fracture in the present embodiment) in the concrete near the main reinforcement 27 of the concrete 22. Further, since the reinforcing bars 84 are provided only at both ends of the beam member 80 where the shear failure at the concrete joining surface M is likely to occur, the cost can be reduced as compared with the case where the reinforcing bars 84 are provided on the entire beam member 80. .

  Further, in the composite beam 82, the fixing portions 84B and 84C, which are both ends of the reinforcing bar 84, are extended in the horizontal direction in the slab concrete 22, so that the adhesion force between the concrete of the slab concrete 22 and the reinforcing bar 84 is increased. Increases, and the displacement of the reinforcing bars 84 can be suppressed.

  In addition, this invention is not limited to said embodiment.

  The concrete placement performed to form the slab concrete 22 may be performed after placing the deck plate in addition to using only the mold 34.

  In the second and third embodiments, when the break mode is determined to be corner split break according to the expressions (1) to (3), the triangular or V-shaped reinforcing bars 74 and 84 are used. When it is determined that the side split fracture has occurred, for example, the rectangular reinforcing bar 64 of FIG. Further, the shape of the reinforcing bars straddling the concrete joining surface M and the assumed splitting surface S is not limited to a triangle or a V shape, and a polygonal shape can be used.

10 Building 20 Beam member (beam member)
21 (half precast beam member)
24 Reinforcing bars (reinforcing bars)
27 Main bars (upper bars)
30 beam members (beam members)
40 beam members (beam members)
50 Beam members (beam members)
51 (half precast beam member)
54 Reinforcing bars (reinforcing bars)
60 Beam members (beam members)
70 Beam members (beam members)
71 (half precast beam member)
74 Reinforcement (Reinforcement)
80 Beam members (beam members)
81 (half precast beam member)
84 Reinforcement (Reinforcement)
M Concrete transfer surface S Assumed split surface

Claims (5)

Half precast beam members with exposed upper rebar;
One or more reinforcing bars that are embedded side by side in a direction that intersects the axial direction of the half precast beam member, and are disposed across the concrete connection surface of the half precast beam member a plurality of times,
A beam member.   The beam member according to claim 1, wherein the reinforcing bar is a reinforcing bar formed in a spiral shape.   The beam member according to claim 2, wherein the reinforcing bar is formed in a square shape when viewed in the direction of the central axis of the spiral.   2. The beam member according to claim 1, wherein the reinforcing bar is disposed across both an assumed split surface in which a split is assumed in the vicinity of the upper reinforcing bar when an external force is applied and the concrete connection surface.   The beam member according to any one of claims 1 to 4, wherein the reinforcing bars are provided only at both ends in the axial direction of the half precast beam member.

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