JP3833627B2 - Joint structure of precast concrete slab - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a joint structure of a precast concrete floor slab used for construction of a bridge roadbed and the like, and particularly relates to a joint structure of a precast concrete floor slab having increased joint strength.
[0002]
[Prior art]
The slabs that make up the roadbed of the bridge directly support the load of a traveling car, etc. In constructing such a roadbed, such as homogenizing strength, ensuring design accuracy, and shortening the construction period, etc. In response to demands, precast concrete floor slabs (hereinafter abbreviated as “PC floor slabs”) that have been blocked by factory manufacture have been widely used. There is a construction method in which a plurality of these are arranged adjacent to each other according to the extension of the bridge construction, and the adjacent end faces that become the joints are connected to each other by reinforcing the reinforcing bars protruding from the end faces, and then filled with the interstitial concrete. It is taken.
[0003]
As shown in FIG. 8, the structure of these joint portions is a reinforcing bar a <b> 1 (hereinafter, abbreviated as “loop reinforcement”) that extends in a predetermined length from the end face and then curves or bends to return to the original end face. ) Are protruded from the end surfaces of the PC floor slabs A close to each other, alternately approaching each other, and the loop streaks a1 arranged so as to overlap in a side view are fastened to each other, and then an end surface serving as a joint portion thereof A structure is adopted in which the interstitial concrete a2 is placed between and integrated. Such a reinforcing bar arrangement is intended to compensate for the weakness of the tensile strength of the concrete structure in which tensile stress and compressive stress act on the cross section of the joint portion by the load with the neutral axis C as a boundary.
[0004]
Further, as shown in FIG. 9, the loop reinforcement b1 of the PC floor slab B is formed in a rectangular shape, and after placing the steel plate b3 facing each other in the longitudinal direction of each inner position of the loop reinforcement b1, There are some which place b4 and change the tensile force acting on the loop reinforcement b1 to the compressive force to the interstitial concrete to improve the force transmission and improve the joint strength (see, for example, Patent Document 1). ).
[0005]
[Patent Document 1]
JP-A-8-326197 (page 3-5, FIG. 1)
[0006]
[Problems to be solved by the invention]
However, in the joint structure of the PC floor slab A shown in FIG. 8, the adhesion between the reinforcing bar itself and the concrete is originally low, so that the protrusion length of the loop reinforcement a1 must be increased in order to ensure sufficient joint strength. It was. Along with this, the distance between the end faces of the joint portion increases and a large amount of concrete a2 is required, which is disadvantageous in terms of economy and curing time, and in addition to the bridge constituted by the main girder D having a small flange d1 width. There was a problem that was not applicable.
[0007]
Further, in the joint structure of the PC floor slab B shown in FIG. 9, since the variation in the protruding length of the loop reinforcement b1 is large, there is a gap between the loop reinforcement b1 and the steel sheet b3 when the steel plate b3 is long in the longitudinal direction of the joint. Therefore, there is a problem in the adhesion between the reinforcing bar and the steel plate, and the force transmission from the loop reinforcement b1 to the steel plate b3 is poor. Further, in order to ensure adhesion, measures such as installing protrusions and dowels on the steel plate b3 are taken. However, the steel plate b3 having such specifications has not only insufficient force transmission but also a problem that costs increase.
[0008]
Furthermore, when a bending moment is applied to the loop reinforcement b1 due to the load, the reinforcing bar b2 (hereinafter referred to as “tensile reinforcement”) on which the tensile force acts is eccentric with respect to the steel sheet b3. There was also a problem that power transmission efficiency to b3 was poor.
[0009]
【the purpose】
Therefore, the present invention has been made in view of the above-mentioned problems, and in the joint structure of a precast concrete floor slab, the distance between the end faces of the joint portion is shortened, and a new structure is adopted for the steel sheet interposed between the reinforcing bars. Thus, a joint structure of a precast concrete floor slab that enables transmission of a force that converts a tensile force applied to a reinforcing bar acting on a cross section of a concrete joint to a compressive force applied to concrete is provided.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the joint structure of the precast concrete floor slab according to the present invention is configured as follows.
[0011]
That is, the precast concrete floor slabs (1) are continuously arranged adjacent to each other, and between the end faces (11) where the reinforcing bars (3) are protruded and connected in a substantially horizontal direction from the opposite end faces (11). In the joint structure of the floor slab that is filled and integrated with the stuffed concrete (5), the horizontally opposed reinforcing bars (3) protruded are arranged alternately or at an appropriate interval, and the reinforcing bars ( A compression plate (4) having a height dimension from 3) to the neutral axis (C) of the joint part (2) functioning as the joint structure and having a surface perpendicular to the reinforcing bar (3) It is characterized by being attached to the tip (31a, 32a) of the reinforcing bar (3).
[0012]
In addition, in attaching the compression plate (4), the compression plate (4) is attached in a standing manner to the tip portions (31a, 32a) of the reinforcing bars (3) respectively protruding from the upper and lower portions of the end surface (11), and A rib plate (41) for connecting the compression plate (4) and the rear surface in the axial direction of the reinforcing bar (3) is attached. In addition, when attaching this rib plate (41), the height dimension of the compression plate (4) is not limited to the height dimension up to the neutral axis (C) of the joint part (2) described above. Also good.
[0013]
Furthermore, it is characterized in that either or both of the protruded reinforcing bars (3) and the compression plates (4) are connected by a through bar (33) arranged in the width direction of the end surface (11).
[0014]
In addition, the reference numerals in parentheses described in the section of the claims and means for solving the problems are added with reference numerals for reference to facilitate understanding of the configuration of the invention. Of course, it is not limited to the form.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Specific embodiments of a joint structure of a PC floor slab according to the present invention (hereinafter abbreviated as “joint structure”) will be described below in detail with reference to the drawings.
[0016]
FIG. 1 is an external perspective view showing an entire floor slab constructed with the joint structure of this embodiment and a PC floor slab, and FIG. 2 is a partially enlarged perspective view showing a connected state of the PC floor slab of this embodiment. 3 is a cross-sectional view taken along line AA of FIG. 1 showing the joint structure of the present embodiment, FIG. 4 is a cross-sectional view taken along line BB of FIG. 1 showing the joint structure of the present embodiment, and FIG. It is a partially expanded perspective view which shows the arrangement | positioning state of the reinforcing bar and compression board of an example PC floor slab.
[0017]
The PC floor slab 1 which is the object of the present embodiment is connected as follows to construct a series of integrated road floors and supports a load G of an automobile or the like.
[0018]
That is, as shown in FIG. 1, a plurality of PC floor slabs 1 are arranged on the flange d1 of the main girder D laid in parallel with the end faces 11 facing each other, and as shown in FIG. A horizontally opposed reinforcing bar 3 (hereinafter abbreviated as “reinforcing bar”) composed of an upper bar 31 and a lower bar 32 attached in a protruding manner from two locations above and below the end surface 11 and the compression plates 4 fixed to the reinforcing bar 3. The joint portion 2 is configured by being arranged close to each other so as to alternately face each other and overlap in a side view.
[0019]
Next, in each PC floor slab 1 overlapped by the joint portion 2, on the width direction side of the bridge (cross section taken along line AA in FIG. 1), as shown in FIG. A rectangular compression plate 4 having a surface perpendicular to the width and extending in the width direction of the joint portion 2 is erected. Further, the compression plate 4 is provided with a rib plate 41 having a substantially right-angled triangle in a side view in an integrally fixed manner along the length direction of the upper peripheral surface of the lower bar 32. A through hole 42 for a through bar 33 made of a reinforcing bar or PC steel wire arranged in the longitudinal direction is formed.
[0020]
Finally, the interstitial concrete 5 is cast and filled in the joint portion 2 and the adjacent PC floor slabs 1 are connected and integrated to form a road bed. In addition, on the bridge length direction side of the bridge of the joint portion 2 (BB line cross section in FIG. 1), as shown in FIG. 4, the arrangement of the compression plate 4 and the rib plate 41 is in the width direction side (AA line cross section in FIG. 1). On the contrary, the compression plate 4 is arranged to be fixed downward from the distal end portion 31 a of the upper muscle 31.
[0021]
A joint portion 2 that functions as a joint structure of the above-described PC floor slab 1 includes a reinforcing bar 3 protruding from the PC floor slab 1, a compression plate 4 attached to the tip of the reinforcing bar 3, and a filling concrete 5 that is cast and filled. It is mainly composed.
[0022]
First, the PC floor slab 1 is manufactured in advance in a factory, and as shown in FIG. 5, the cross-sectional areas on both sides placed on the flange d1 of the main girder D are slightly thickened to form a trapezoidal shape. The haunch 12 is formed integrally from the lower edge of both sides (the width direction side of the bridge) orthogonal to the main girder D of the PC floor slab 1 so as to protrude like a shelf. The haunch 12 functions as a bottom mold that abuts between the opposing end surfaces of the adjacent PC floor slabs 1 via the joint material 21 when the PC floor slab 1 is laid and covers the lower surface side of the joint portion 2. This ensures the holding of the interstitial concrete 5 cast in the joint portion 2.
[0023]
Further, on each end face 11 of the PC floor slab 1, reinforcing bars 3 composed of a plurality of upper bars 31 and lower bars 32 are arranged at equal intervals so as to protrude from two places in the vertical direction (or planted), The compression plate 4 and the rib plate 41 are disposed at the tip portions 31 a and 32 a of the reinforcing bar 3. A through hole 42 is formed in the rib plate 41 in order to arrange a through bar 33 that is traversed in the longitudinal direction of the joint portion 2.
[0024]
The compression plate 4 is made of a rectangular plate-shaped steel material having a predetermined thickness, and the rib plate 41 is a substantially right-angled triangular plate-shaped steel material. As shown in FIGS. 2 and 3, the compression plate 4 has a height dimension of about the neutral axis C of the joint portion 2 on the width direction side (cross section taken along the line AA in FIG. 1) and has a lower bar 32. It is reinforced by a rib plate 41 that is fixed to the front end portion 32a in a standing manner and is attached along the length direction of the upper peripheral surface of the lower bar 32. On the bridge length direction side (BB line cross section in FIG. 1), it is opposite to the width direction side (AA line cross section in FIG. 1) side and has a height dimension of about the neutral axis C of the joint portion 2. The compression plate 4 and the rib plate 41 are fixed to the tip 31 a of the upper bar 31 and the lower peripheral surface of the upper bar 31. These attachments are integrated with each upper bar 31 or lower bar 32 by welding (or gas pressure welding) or the like.
[0025]
In other words, the above-described arrangement position of the compression plate 4 with respect to the reinforcing bar 3 is a portion on which a tensile stress acts on the cross-sectional force generated by the load G. That is, as shown in FIG. 3, in the case of the width direction side (cross section taken along line AA in FIG. 1) of the bridge on which a bending moment having a downward convex curve acts, it is below the neutral axis C and shown in FIG. Thus, in the case of the bridge length direction side (BB line cross section of FIG. 1) of the bridge on which the bending moment that becomes convex upward acts, it is above the neutral axis C.
[0026]
Further, a through hole 42 through which the through bar 33 is penetrated is formed on the side surface of the rib plate 41. The position of the through hole 42 overlaps with each other in the opposing PC floor slab. The center line is positioned on the center line in the short direction of the joint portion 2.
[0027]
Note that the width of each compression plate 4 is such that the compression plate 4 of another PC floor slab 1 that is disposed adjacent to each other within a range extending at least 45 degrees from the side edges of each compression plate 4 enters. The board width is set.
[0028]
The PC floor slab 1 configured as described above has the reinforcing bars 3 arranged at equal intervals (one pitch “P”) on each side in the width direction and the bridge length direction. When the PC floor slabs 1 are arranged adjacent to each other, the interval between the reinforcing bars 3 that have faced each other is set to ½ P. Therefore, the PC floor slab 1 has an arrangement of the reinforcing bars 3 on the end surface 11 in each of the width and the bridge length. There are two types formed by shifting by 1 / 2P in the direction of.
[0029]
[Operation of this embodiment]
The joint structure of the present embodiment acts as follows depending on the load G applied to the roadbed.
[0030]
That is, in the joint portion 2 on the width direction side (cross section along line AA in FIG. 1), the tensile force T acts on the lower muscle 32 by the action of the bending moment M that is downwardly curved downward on the neutral axis, and thus the conventional structure Has borne this acting force only by the adhesion force to the concrete 5 packed between the reinforcing bars 3.
[0031]
However, due to the arrangement of the compression plate 4 which is the main object of the present invention, the tensile force T acting on the lower muscle 32 is converted into a compression force to the interstitial concrete 5 by narrowing the interval between the compression plates 4 facing each other. . As a result, the compressive stress σ having a triangular distribution acts on the interstitial concrete 5 between the compression plates 4 in a sectional view of the joint portion 2 as shown in FIG. Further, in the top view of this portion, due to the arrangement relationship of the compression plates 4 that are opposed and arranged in a staggered manner, as shown in FIG. The pressure distribution has an expansion angle α, and in this range, the concrete portion is sufficiently compressed, and the joint portion 2 is more integrated and its connection strength is improved.
[0032]
In the joint portion 2 on the bridge length direction side (BB line cross section in FIG. 1), a bending moment M that is convex upward acts, and in this case, it is upside down from the above case, and the tensile force is applied to the upper bar 31. T will act.
[0033]
However, the compression plate 4 disposed on the upper muscle 31 opposite to the width direction side (cross section along line AA in FIG. 1) causes the tensile force T acting on the upper muscle 31 to be opposed to the compression plate 4 via the compression plate 4. As shown in FIG. 7A, the compressive stress σ having a triangular distribution acts on the interstitial concrete 5 between the compression plates 4 in the sectional view of the joint portion 2. It becomes. In addition, in a top view of this portion, as shown in FIG. 7B, the pressure distribution has a spread of approximately 45 degrees as in the cross section side of the line AA and each α has a sufficient compression state in this range. The joint portion 2 is more integrated and the connection strength is improved.
[0034]
【effect】
Since this invention is comprised as mentioned above, it has the following effects.
That is, because the compression plates are arranged opposite to each other on the opposite side of the reinforcing bar, the tensile stress distributed outside the convex curve of the interstitial concrete placed in the joint is directly and efficiently provided. Therefore, it is possible to transmit the force between the reinforcing bars, which is changed into the compressive stress, and to provide a joint structure with further improved strength.
[0035]
In addition, the improved joint strength makes it possible to shorten the joint compared to the conventional case. Therefore, the construction period can be shortened and the cost can be reduced by reducing the volume of the concrete to be placed, and the flange width is narrow. It can also be applied to bridges, and the flexibility of floor slab manufacturing construction can be improved.
[Brief description of the drawings]
FIG. 1 is an external perspective view showing an entire floor slab and a PC floor slab constructed with a joint structure according to an embodiment of the present invention.
FIG. 2 is a partially enlarged perspective view showing a connected state of the PC floor slab of the embodiment.
3 is a cross-sectional view taken along the line AA in FIG. 1 showing a joint structure according to this embodiment.
4 is a cross-sectional view taken along the line BB of FIG. 1 showing the joint structure of the embodiment.
FIG. 5 is a partially enlarged perspective view showing an arrangement state of reinforcing bars and compression plates of the PC floor slab of the embodiment.
FIG. 6 is an explanatory diagram showing a stress distribution state due to a load in the joint structure of the embodiment.
FIG. 7 is an explanatory view showing a stress distribution state due to a load in the joint structure of the embodiment.
FIG. 8 is a cross-sectional view showing a joint structure of a conventional floor slab PC.
FIG. 9 is a cross-sectional view showing a joint structure of a conventional floor slab PC.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 PC floor slab 11 End surface 12 Haunch 2 Joint part 21 Joint material 3 Reinforcing bar 31 Upper bar 31a Tip part 32 Lower bar 32a Tip part 33 Through bar 4 Compression board 41 Rib board 42 Through hole 5 Packing concrete A PC floor board (conventional) Example 1)
a1 Loop reinforcement a2 Filled concrete B PC floor slab (conventional example 2)
b1 Loop Reinforcement b2 Tensile Reinforcement b3 Steel Plate b4 Filled Concrete C Neutral Shaft (of Joint Section)
D Main girder d1 Flange σ Compression stress G Load M Bending moment P Pitch (rebar spacing)
T Tensile force

Claims (4)

Precast concrete floor slabs (1) are arranged adjacent to each other, and between the end faces (11) where the reinforcing bars (3) protrude from the opposing end faces (11) in a substantially horizontal facing direction and are connected to each other, the interstitial concrete In the joint structure of the floor slab filled with (5) and integrated,
The horizontally opposed reinforcing bars (3) that are projected are arranged alternately or at an appropriate interval, and the neutral shaft (C) of the joint portion (2) that functions as the joint structure from the reinforcing bars (3). ), And a compression plate (4) having a height dimension up to about and having a surface perpendicular to the reinforcing bar (3) is attached to the tip (31a, 32a) of each reinforcing bar (3). The joint structure of precast concrete floor slab. Precast concrete floor slabs (1) are continuously arranged adjacent to each other, and between the end faces (11) where the reinforcing bars (3) protrude from the opposed end faces (11) in a substantially horizontal facing direction and are connected to each other, the interstitial concrete is provided. In the joint structure of the floor slab filled with (5) and integrated,
The horizontally opposed reinforcing bars (3) that are protruded are arranged alternately or at an appropriate interval, and the tip ends (31a, 32a) of the reinforcing bars (3) that protrude from the upper and lower portions of the end surface (11), respectively. ) And a rib plate (41) for connecting the compression plate (4) and the axially rear surface of the reinforcing bar (3) is attached in a standing manner. Precast concrete floor slab joint structure characterized by In attaching the compression plate (4),
A compression plate (4) is mounted upright on the tip (31a, 32a) of the reinforcing bar (3) protruding from the upper and lower portions of the end surface (11), and the compression plate (4) and the reinforcing bar (3). A joint structure for a precast concrete floor slab according to claim 1, wherein a rib plate (41) for connecting the rear surface in the axial direction is attached.   One or both of the protruding reinforcing bars (3) and the compression plates (4) are connected with a through bar (33) arranged in the width direction of the end face (11). Or the joint structure of the flooring made from precast concrete of 3 description.

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