JP3682520B2 - PC steel wire anchorage structure in composite bridge girder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of girder bridges, and particularly relates to the structure of a PC steel wire fixing portion in a composite bridge girder composed of a steel box girder, concrete, and PC steel wire.
[0002]
[Premise of the invention]
Generally, a girder bridge is constructed by building a bridge girder on an abutment and a pier, forming a floor slab on the bridge girder, and further laying asphalt or the like thereon to form a floor slab.
[0003]
Conventional girder bridges include a concrete girder bridge formed by formwork and a steel girder bridge constructed only of steel materials (steel plates) and have been widely used.
[0004]
The bridge girder of such a concrete girder bridge is formed by casting concrete and has a structure that complements the lack of tensile strength of the concrete material by introducing prestress due to the inclusion of high-strength steel wire (hereinafter abbreviated as “PC steel wire”). The material itself is inexpensive, but the work costs such as assembly / removal of the formwork and the layout are inevitable.
[0005]
On the other hand, steel girder bridge girder is lighter than concrete girder bridge girder and has the advantage of shortening the construction period by factory production, but it has the disadvantage that material cost and transportation cost of large workpiece are expensive. there were.
[0006]
Therefore, the applicant of the present application has previously filed a composite bridge girder that takes advantage of both the steel girder bridge girder and the concrete girder bridge girder as Japanese Patent Application No. 2001-333926. Such a composite bridge girder has a structure in which prestressed concrete is cast in the internal space of a steel box girder made of steel instead of a concrete casting form.
[0007]
[Prior art and problems to be solved by the invention]
The above composite bridge girder achieved the intended purpose and had excellent technical effects. However, in the fixing part that holds the PC steel wire at both ends, the load and pre-stress (tension) ) Introduces a large reaction force (compression force) from the PC steel wire, and most of the reaction force acts on concrete whose Young's modulus is about 1/7 that of steel materials (steel box girders). Met. Therefore, the inventor of the present application has come up with a new invention as a result of further improving and developing the function of the fixing portion to improve the durability of the composite bridge girder.
[0008]
【the purpose】
That is, the present invention has been made on the basis of the above problems, and the reaction force by the PC steel wire of the box girder made of steel is equally applied to the cast concrete and the steel near the both ends of the box girder. The structure of the PC steel wire anchoring part in the new composite bridge girder intended to be distributed is provided.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the structure of the PC steel wire fixing portion in the composite bridge girder of the present invention is configured as follows.
That is, the PC steel wire (2) supported at both ends is stretched in the span direction in the internal space of the steel box girder (1), and after placing concrete (7), prestress is applied to the PC steel wire (2). In the composite bridge girder that is introduced, the fixing part (3) of the PC steel wire (2) is plural one each so as to close the cross section near the both ends of the box girder (1), or at a predetermined interval in the span direction. The reaction steel plate (4) was placed, and the reaction steel plate (4) was penetrated so that both ends of the PC steel wire (2 ) were fixed to the concrete (7) cast and hardened. It is a feature.
[0010]
Further, one or a plurality of through holes (40) are formed in a matrix in the reaction steel plate (4), and the PC steel wire (2) is fixed by passing through each through hole (40). It is said.
[0011]
Further, particularly, when a plurality of reaction force steel plates (4) are arranged at predetermined intervals in the span direction, the reaction force steel plates (4) are connected and integrated by a connection steel plate (6) extending in the span direction. In the connection between the connecting steel plate (6) and the reaction steel plate (4), the box girder (1) is arranged in a lattice shape when viewed from above.
[0012]
Furthermore, the rib steel plate (5) extended to a span direction is arrange | positioned in the attachment part of the reaction force steel plate (4) in the inner surface of a box girder (1), It is characterized by the above-mentioned.
[0013]
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.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Below, the concrete embodiment example of the structure of the PC steel wire fixing part in the composite bridge girder according to the present invention will be described in detail based on the drawings.
[0015]
FIG. 1 is an overview diagram showing a construction example of a girder bridge. FIG. 2 is a perspective view showing the present embodiment and an enlarged view showing a part of the extracted perspective view. FIG. 3 is a view showing the embodiment, and is cut in the span direction. FIG. 4 is a longitudinal sectional view (A) and an enlarged sectional view (B) taken along line AA in FIG. (A), and FIG. 4 is a plan view partially cut away from the present embodiment. Further, FIG. 5 is an explanatory view showing the action state of the force in this embodiment.
[0016]
First, as shown in FIG. 1, the girder bridge B having the bridge girder structure is constructed by laying the composite bridge girder Mb in parallel with the abutment A or the pier P or by connecting with the cross girder C and forming the floor slab D on the upper part. Later, asphalt or the like is laid on the upper surface.
[0017]
As shown in FIG. 2, the structure of the PC steel wire fixing portion in the composite bridge girder of the present invention is mainly a box girder 1, a PC steel wire (high-strength steel wire) 2, a reaction steel plate 4, a connecting steel plate 6, and It consists of concrete 7.
[0018]
The box girder 1 is made of a steel material such as a steel plate and has a long rectangular bottom plate 10 extending in a span direction (or a bridge extending direction) and a web 11 formed so as to be opposed to both sides of the long rectangular bottom plate 10. It is a long box-like body that is substantially U-shaped. Long web-like flanges 12 for supporting the floor slab D are formed continuously from the upper ends of both webs 11 in the outer horizontal direction and in the span direction.
[0019]
The PC steel wire 2 is a wire made of a high-strength steel wire for introducing prestress into the filled concrete, and is inserted through a sheath (cladding tube) 20 and stretched in the span direction of the internal space of the box girder 1, It is held in the fixing unit 3 near both ends. In this embodiment, the total number is 12 in 3 rows and 4 columns. As shown in FIG. 3 (A), the PC steel wire 2 is disposed through a rack 21 disposed opposite to the central portion of the box girder 1, and the bottom plate 10 side is disposed between the racks 21. It is configured to be horizontal in a state of being close to and converged with. This takes into account the distribution of cross-sectional force due to girder loads.
[0020]
Next, as shown in FIGS. 2 and 3B, the fixing unit 3 that is the main subject of the present application is configured by a reaction force steel plate 4, a connecting steel plate 6, and a rib steel plate 5.
[0021]
The reaction force steel plate 4 is formed of a rigid plate and blocks a plurality of pieces (three pieces in the present embodiment) of the box girder 1 with a predetermined separation distance in the span direction so as to close a cross section near both ends of the box girder 1. It is integrated with the inner wall. A plurality of through-holes 40 having an opening shape (rectangular shape in the present embodiment) through which the sheath 20 through which the PC steel wire 2 is inserted can pass through each plate surface of the reaction steel plate 4 with a sufficient gap. Is forming. The through holes 40 are arranged in a substantially equidistant matrix (in this embodiment, a total of 12 in 4 rows and 3 columns), and the corresponding through holes 40 of each reaction steel plate 4 follow the arrangement of the PC steel wires. The array is formed so as to communicate in a straight line. In addition, the arrangement | positioning number of this reaction force steel plate 4 is an appropriate thing of 1 or several sheets.
[0022]
Further, a strip-shaped rib steel plate 5 extending in the span direction is attached perpendicularly to the inner surface of the web 11 of the box girder 1 and perpendicular to the reaction force steel plate 4. A semicircular cutout 50 is formed in the rib steel plate 5 at a portion perpendicular to the reaction force steel plate 4 so as to correspond to the positions of the through holes 40 of the reaction force steel plate 4 (four in this embodiment). It arrange | positions in a direction and each reaction force steel plate 4 is connected. This arrangement reinforces the attachment of the reaction steel plate 4 to the web 11.
[0023]
Further, between the reaction force steel plates 4 that are spaced apart in the span direction, there is provided a connection steel plate 6 that is orthogonal to the plate surface of the reaction force steel plate 4 and arranged in parallel with the web 11. The connecting steel plates 6 are attached between the rows of the matrix-formed through-holes 40 (two locations in this embodiment), so that, as shown in FIG. It arrange | positions so that it may become a grid | lattice in positional relationship.
[0024]
Due to the lattice arrangement formed by the reaction steel plate 4 and the connecting steel plate 6, the fixing unit 3 has a laminated structure of rectangular boxes, and exhibits a strong shape retaining force in the span direction and the direction orthogonal thereto. Will be.
[0025]
A large number of PC steel wires 2 inserted and stretched through the sheath 20 in the box girder 1 are distributed for each wire and penetrate the through holes 40 of the respective reaction force steel plates 4, and both ends are fixed at the fixing portion 3. Hold.
[0026]
Under such a configuration, the concrete 7 is placed in the internal space of the box girder 1 and cured. After the hardening, a fixing tool 30 having a right truncated cone shape and having a fixed bottom plate 30a is attached to the tip of the PC steel wire 2 and is pulled and fixed with a predetermined tension. As shown in FIG. 5, the reaction force state in the fixing unit 3 is prestressed (compressed) into the concrete 7 in which the reaction force of the residual tension of the PC steel wire 2 is cast and hardened through the expanded base plate 30 a of the fixing tool 30. Force).
[0027]
As a result, the reaction force of the bottom expansion plate 30a is distributed and distributed in the concrete 7 in contact therewith, and acts on the plate surface of the reaction force steel plate 4 in a distributed manner. The acting force transmitted from the reaction force steel plate 4 due to this action is further filled with concrete 7 filled in a rectangular box-like laminated space formed by a lattice arrangement of the reaction force steel plate 4 and the connecting steel plate 6. It is transmitted in a three-dimensional distributed manner and acts more evenly. As a result, it is possible to prevent the concrete 7 and the box girder 1 from being broken due to the stress concentration, thereby realizing a more durable shape retaining force and retaining force of the fixing unit 3.
[0028]
【effect】
Since the present invention is configured as described above, it is possible to realize more durable shape retaining force / holding force in the fixing portion of the PC steel wire in the composite bridge girder, and the girder bridge using the composite bridge girder The overall strength can be improved and the life can be extended.
[Brief description of the drawings]
FIG. 1 is an overview diagram showing a construction example of a girder bridge.
FIG. 2 is a perspective view showing an example of the present embodiment and an enlarged view showing a part extracted from the perspective view.
FIG. 3 is a view showing an example of the present embodiment, and is a longitudinal sectional view (A) cut along a span direction and an enlarged sectional view (A) taken along line AA in FIG.
FIG. 4 is a plan view showing a part of the embodiment cut away.
FIG. 5 is an explanatory diagram showing a force application state in the embodiment.
[Explanation of symbols]
1 Box girder 10 Bottom plate 11 Web 12 Flange 2 PC steel wire 20 Sheath (cladding tube)
21 Rack 3 Fixing part 30 Fixing tool 30a Bottom plate 4 Reaction force steel plate 40 Through hole 5 Rib steel plate 50 Notch 6 Connection steel plate 7 Concrete A Abutment B Girder bridge C Girder D Floor slab P Bridge pier Mb Composite bridge girder

Claims (5)

PC steel wire (2) supported at both ends is stretched in the span direction in the internal space of the steel box girder (1), and concrete (7) is placed, and then prestress is introduced into the PC steel wire (2). In the composite bridge girder
A plurality of reaction force steel plates (4) are arranged so as to block the cross section near both ends of the box girder (1), respectively, or at a predetermined interval in the span direction,
A structure of a PC steel wire fixing portion in a composite bridge girder characterized in that the reaction steel plate (4) is penetrated and both ends of the PC steel wire (2 ) are fixed to concrete (7) cast and hardened .   One or a plurality of through holes (40) are formed in a matrix in the reaction steel plate (4), and the PC steel wire (2) is fixed by passing through each through hole (40). The structure of the PC steel wire fixing part in the composite bridge girder according to claim 1. In the structure of the PC steel wire fixing part in the composite bridge girder according to claim 1 or 2, particularly when a plurality of reaction force steel plates (4) are arranged at a predetermined interval in the span direction,
The structure of the PC steel wire fixing part in the composite bridge girder, wherein the reaction steel plates (4) are connected and integrated by the connecting steel plates (6) extending in the span direction.   4. The PC steel wire in the composite bridge girder according to claim 3, wherein the connection steel plate (6) and the reaction force steel plate (4) are arranged so as to have a lattice shape in a top view of the box girder (1). The structure of the fixing unit.   5. The composite according to claim 1, 2, 3, or 4, wherein a rib steel plate (5) extending in the span direction is disposed on a mounting portion of the reaction steel plate (4) on the inner surface of the box girder (1). Structure of PC steel wire fixing part in bridge girder.

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