JPH11148110A - Continuous girder bridge - Google Patents

Abstract

(57) [Problem] A continuity that can be configured simply and at low cost, can withstand the compressive stress in the bridge axis direction under the bridge body due to the action of a negative bending moment, and has a degree of freedom in appearance. Provide a girder bridge. SOLUTION: A continuous girder bridge 1 is supported by a bearing 3 in which a bridge 2 formed by a floor slab 20 and a girder 10 is arranged at a predetermined interval, and the girder 10 is a steel girder 11 continuous in the bridge axis direction.
Are provided in the width direction of the bridge, and a concrete slab 12 is erected and fixed between them, and is configured in a box-shaped cross section together with the floor slab 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous girder bridge which is used for a bridge such as a viaduct and has a structure in which a bridge body continuous in the bridge axis direction is supported by a plurality of bearings.

[0002]

2. Description of the Related Art As a bridge structure such as a viaduct for an automobile road or a bridge for a railway, there is a so-called continuous girder bridge having a structure in which a bridge body continuous in the bridge axis direction is supported by a plurality of bearings.

[0003] In such a continuous girder bridge, a negative bending moment acts on the bridge body 2 as shown in Figs. That is, the shoring 4 shown in FIG.
In the case of erection using a bridge, a positive bending moment acts on the bridge 2 between the bearings 3 as shown in the bending moment diagram of FIG. Moment acts. In the case of the overhanging erection shown in FIG. 14A, a negative bending moment acts on the whole as shown in the bending moment diagram of FIG. Large in the part to be done.

[0004] In a portion where such a negative bending moment acts, a compressive stress in the bridge axis direction is generated below the bridge body 2 (girder), and therefore it is necessary to be configured to withstand this compressive stress. For this reason, as shown in FIG. 15, the girder height is increased only in the relevant portion, or the girder thickness is increased. In addition, a truss structure is also used.

[0005]

However, as described above, in the bridge configuration in which only the supported portion is supported by the bearing, the structure is complicated, the production is troublesome, the cost is increased, and the girder height is reduced. If the height is partially increased, there is also a problem that the appearance is defined by the structure.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can be constructed simply and at low cost, and can withstand compressive stress in the bridge axis direction below the bridge body due to the action of a negative bending moment. It is an object of the present invention to provide a continuous girder bridge capable of achieving a high degree of freedom in appearance.

[0007]

A continuous girder bridge according to the present invention, which achieves the above object, comprises a steel girder having at least one pair of steel girder members extending in the axial direction of a bridge to support a floor slab and to adjoin the steel girder. A concrete slab is disposed between lower flanges of the girder, and the floor slab, the steel girder, and the concrete slab form a box-shaped cross section, and the concrete slab bears compressive stress when a negative bending moment is applied. It is characterized by having such a configuration.

[0008] Further, the concrete slab is characterized in that it is disposed only in a portion corresponding to a bearing of the continuous girder bridge on which a negative bending moment acts.

[0009] Further, the concrete plate is characterized in that a precast plate made of reinforced concrete is erected and fixed between lower flanges of the steel girder.

[0010] The present invention is characterized in that a cast-in-place concrete layer is further formed on the upper side of the precast plate.

The precast plate is erected between lower flanges of the steel girder, and is fixed by cast-in-place concrete cast between a side end thereof and the steel girder. And a connecting member is provided at a position where the steel girder is buried in the cast-in-place concrete.

Further, the connecting member is constituted by providing a horizontal rib member provided on a web of the steel girder with a dowel member which can be protruded and retracted, and the connecting member is provided with the above-mentioned place in a state where the dowel member is protruded. It is characterized by being buried in cast-in-place concrete.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a conceptual front view of a continuous girder bridge which is one configuration example of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

The illustrated continuous girder bridge 1 has a bridge 2 formed by a floor slab 20 and a girder 10 supported by bearings 3 arranged at predetermined intervals.

The girder 10 is provided with a pair of steel girder 11 continuous in the bridge axis direction in the bridge width direction, a concrete slab 12 is erected and fixed between them, and is formed in a box-shaped cross section together with the floor slab 20. ing.

The steel girder 11 has an I-shaped cross section having flanges 11U and 11L provided above and below a belly plate 11W, and the belly plate 11A is disposed vertically. Are combined. The upper flange 11U is formed so as to protrude equally to the left and right with the abdominal plate 11W as a center, and the lower flange 11L projects inward by a predetermined amount (to the opposite side of the left and right steel girders 11). Supports the side edges of

The concrete plate 12 is a precast plate 12 made of reinforced concrete having a predetermined size (width and length).
A is connected to the steel girders 11 at both left and right side edges thereof, and is formed by connecting ones adjacent in the bridge axis direction.

The connection between the precast plate 12A and the steel girder 11 corresponds to the portion X in FIG. 2 and is an enlarged detailed view of the joint portion of the precast plate 12A in the bridge axis direction. As shown in FIG. 4 which is a sectional view corresponding to a plan view before installation (bar arrangement is not shown) and FIG. 5 which is a sectional view corresponding to the BB section in FIG. 4, the precast plate 12A is connected to the left and right steel girders 11, 11. After being arranged via the elastic pad 14 and fixed with the positioning bolts 15, the cast-in-place concrete 12B is cast in place in the space between the side edge of the precast plate 12A and the steel girder 11. .
That is, the concrete slab 12 is formed by the precast slab 12A and the cast-in-place concrete 12B.

The width of the precast plate 12A is smaller by a predetermined amount than the inner width between the webs 11W of the left and right steel girders 11, and the inner width between opposing edges of the lower flange 11L of the steel girder 11. It is set larger by a predetermined amount, and can be placed on the upper surface of the lower flange 11L from the upper side of the disposed left and right steel girders 11. The steel girder 11 can be placed on the upper surface of the lower flange 11L by being inclined from the horizontal even from below. Notches 12 on the upper shoulders on both sides
D is formed, and from the side end surface, upper and lower reinforcing bars 12E disposed in a direction perpendicular to the bridge axis are provided inside the steel beam 11 to be described later as shown in FIG. 6 which is a partial plan view.
Projecting so as not to interfere with the horizontal ribs 31 and the studs 33.

One side of a connecting reinforcing bar 13 formed by bending a reinforcing bar into an L shape is joined to a reinforcing bar 12E protruding from the side end surface, and the other side of the connecting reinforcing bar 13 is connected to a steel beam 11 described later.
The horizontal rib 31 is inserted through the coupling hole 31A.

On the other hand, a connecting member 30 is provided at a portion of the web plate 11W of the steel girder 11 corresponding to the concrete floor slab 12, and the steel girder 11 is connected to a reinforcing bar 12E provided in the precast slab 12A. The connection members 30 and the connection reinforcing bars 13 are connected by the reinforcing bars 13.
2B so as to obtain a bond strength against horizontal shear force.

The connecting member 30 of the steel girder 11 includes a horizontal rib 31 erected on the inner side of the abdominal plate 11W, a dowel 32 attached to the horizontal rib 31, and a stud 33 implanted on the abdominal plate 11W. Consists of

The horizontal rib 31 is positioned horizontally (at the upper and lower flanges 11) at a position substantially corresponding to the center of the thickness of the concrete plate 12.
U, 11L), and its width (the amount of protrusion to the side) is set to have a predetermined distance from the side edge of the precast plate 12A. A plurality of coupling holes 31A having a predetermined diameter are formed at predetermined intervals in the longitudinal direction.

As shown in FIG. 4, the dowel 32 is formed by a steel plate having a predetermined thickness and a fixed base portion 32B having a predetermined width and an arm 32A having a width smaller than the fixed base portion 32B.
It is formed in a planar shape that is extended at a degree. And
The arm 32A is protruded inward, and is fastened and fixed to the horizontal rib 31 at the fixed base 32B by two fixing bolts 34 which are two high-strength bolts arranged in the bridge axis direction. Each of the arms 32A is disposed at an interval substantially twice as large as the dimension in the bridge axis direction. The protruding directions of the arms 32A are vertically reversed in the bridge axis direction, so that the tips of the arms 32A of the upper and lower dowels 32 overlap in a plane, and the overlapping portions of the tips are connected by set bolts 35. . Thereby, the arms 32A of the upper and lower dowels 32 of the reinforcing rib 31 project inward to form a triangle, and the notch 1 of the precast plate 12A is formed.
It is designed to correspond to 2D.

As shown in FIG. 7, the dowel 32 is unfastened by the fixing bolt 34 at the end of the fixing base 32B, and the arm 32A is swung about the other fixing bolt 34 as a fulcrum. By lining the abdominal plate 11W, the horizontal rib 31 can be folded such that the amount of protrusion from the edge toward the inside is reduced. This gives Gibelle 3
2 can be prevented from being obstructed when being transported to the site with the steel girder 11 mounted in advance.
Interference when installing the precast plate 12A on the upper surface of the lower flange 11L can be avoided. In other words, the precast plate 12A can be folded before installation, and can be assembled by swinging after installation.

The stud 33 is a belly plate 11W of the steel girder 11.
Are arranged at predetermined intervals in the direction of the bridge axis vertically above and below the horizontal rib 31, and the height thereof is
In order not to interfere with the installation of A,
Is set substantially equal to

The steel girder 11 and the concrete slab 1 as described above.
According to the joint structure 2, the horizontal ribs 31, the dowels 32, and the studs 33 provided on the web 11 W of the steel girder 11 penetrate into the cast-in-place concrete 12 </ b> B, and the concrete slab 12 is formed.
Is transmitted to the steel girder 11.

That is, the horizontal ribs 31 provided on the web 11W of the steel girder 11 reinforce the buckling strength of the steel girder 11 in the compression area, and are connected by penetrating into the cast-in-place concrete 12B. In addition, the connecting hole 31A formed in the opening improves the biting of the concrete.

The dowel 32 is a cast-in-place concrete 12
B can penetrate deeply into the concrete slab 12 to capture and transmit the shearing force of the concrete slab 12 at a deep position.
Therefore, the steel girder 11 can be easily transported, and interference during installation of the precast plate 12A can be avoided.

With such a configuration, even if the stud 33 alone cannot provide a sufficient penetration depth and it is difficult to arrange the number necessary for transmitting the shearing force, the horizontal rib 3
1 and the dowel 32 can transmit a sufficient shearing force. In the case where the concrete plate 12 is thick and the shearing force to be transmitted is large, the dowel 32 is provided with a plurality of horizontal ribs 31 as shown in FIG. It becomes possible.

On the other hand, as shown in FIG. 9, the joining structure of the precast plates 12A adjacent to each other in the bridge axis direction is joined by mortar or an adhesive 12F with the end faces abutting each other. In other words, the precast plates 12 adjacent in the bridge axis direction
A has no action of an out-of-plane load, and the precast plate 12A bears a compressive stress when a negative bending moment acts on the bridge body 2, so that there is no need to connect a reinforcing bar. It is.

In the continuous girder bridge 1 constructed as described above, the girder 10 is formed by connecting the lower flanges 11L of the I-shaped steel girder 11 having a light weight and a simple shape with the concrete slab 12. Since a box-shaped cross section is formed together with the floor slab 20, high rigidity can be obtained. Since the concrete plate 12 bears the compressive stress caused by the action of the negative bending moment, there is no need to increase the girder height or the plate thickness as in the case of using only the steel girder 11, making production and transportation easier. Not only contribute to cost reduction, but also increase the degree of freedom in bridge design.

When the concrete plate 12 is erected, drying shrinkage is substantially finished in order to use the precast plate 12A formed in a predetermined shape in advance at the factory.
The shrinkage after the start of operation is very small, and the decrease in the function with respect to the compressive stress due to the shrinkage can be suppressed very slightly as compared with the case where the concrete slab 12 is entirely made of cast-in-place concrete.

Furthermore, since the space between the steel girders 11 is closed by the concrete slab 12, the appearance can be made clear and the air can be shielded from the outside air, thereby preventing the accumulation of moisture and the generation of rust caused by bird nesting and the like. Can be prevented. In addition, since the concrete slab 12 can be used as a scaffold at the time of inspection and inspection or maintenance work, the work is facilitated. In terms of appearance, further improvement can be achieved by attaching a decorative plate to the lower surface of the concrete plate 12.

In the above configuration example, the concrete slab 12 is provided over the entire length of the bridge 1. For example, in the case of a structural bridge in which a negative bending moment acts only on the portion supported by the bearing, As shown in the conceptual view of FIG. 10, the concrete slab 12 may be provided only at the portion supported by the bearing 3. In that case, in order to maintain the appearance and airtightness, it is only necessary to dispose the decorative plate at a position where the concrete plate 12 is unnecessary.

Further, as shown in FIG. 11, the thickness of the concrete slab 12 may be changed for each part in accordance with the magnitude of the negative bending moment acting.

Further, when it is desired to reduce the weight of the precast plate 12A from the viewpoint of transportation and erection work, as shown in FIG. 12, a reinforcing bar 12G is assembled on the upper surface of the precast plate 12A, and the precast plate 12A and the steel beam 11 are joined. When the cast-in-place concrete 12B is cast, concrete may be cast on the precast plate 12A to form the concrete layer 12H to form the concrete plate 12 having a desired thickness. That is, the thickness of the precast plate 12A is a part of the total thickness of the concrete plate 12, and the remainder is formed by cast-in-place concrete 12B, 12H. In this configuration, the precast plate 12A functions separately as a formwork. There is no need to prepare formwork or shoring.

The above configuration example is an example in which the present invention is applied to a pair of bridges with steel girders 11. However, it is needless to say that the present invention may be applied to a bridge having two or more (three or more) steel girders. is there.

[0039]

As described above, according to the continuous girder bridge of the present invention, the concrete slab is disposed between the lower flanges of the adjacent steel girders, and the box-shaped section is formed by the floor slab, the steel girder and the concrete slab. The concrete slab is designed to bear the compressive stress when the negative bending moment acts, so that high rigidity can be obtained and the concrete slab can be compressed by the negative bending moment. There is no need to increase the girder height or the plate thickness as in the case of steel girders alone, and the structure is simple, making production and transportation easy, and can contribute to cost reduction.
The degree of freedom in bridge design is also improved. Also, if a concrete slab is provided over the entire bridge, the space between the steel girders will be closed by the concrete slab. Rust can be prevented from occurring, and the work can be facilitated because the concrete slab can be used as a scaffold for inspection, inspection and maintenance work.

Further, since the concrete slab is provided only at a portion corresponding to the bearing of the continuous girder bridge on which the negative bending moment acts, a lightweight and rational configuration can be achieved.

The concrete slab is constructed such that a precast slab made of reinforced concrete is erected and fixed between lower flanges of steel girders, so that the precast slab produced at the factory is transported to the site and fixed. The on-site construction period can be shortened, the construction process management becomes easy, and the drying and shrinkage of the precast plate is almost completed when erected, and the shrinkage after the start of operation is minimal, and the function for compressive stress due to shrinkage is reduced. Can be suppressed very slightly as compared with a concrete slab made of all cast-in-place concrete.

Further, since the concrete slab is further formed on the upper side of the concrete slab, the weight of the concrete slab can be reduced, and the production, transportation and erection of the concrete slab are facilitated.

Further, the precast slab is fixed by the cast-in-place concrete cast between the side end and the steel girder to form a concrete slab, and the precast slab is placed at a position where the steel girder is buried in the cast-in-place concrete. Since the connecting member is provided, it can be firmly connected so that the shear force of the precast plate can be efficiently transmitted to the steel girders.

Further, the connecting member is constituted by providing a horizontal rib member provided on a steel girder plate with a dowel member capable of projecting and retreating, and burying in a cast-in-place concrete with the dowel member protruding. By placing the precast plate between the steel girders, it is possible to prevent interference with the precast plate by placing the dowel member in the retracted state, and to facilitate the installation of the precast plate. By projecting it, the amount of penetration into cast-in-place concrete can be set large, and the precast slab can be firmly joined so that the shearing force can be efficiently transmitted to the steel girders.

[Brief description of the drawings]

FIG. 1 is a conceptual front view of a continuous girder bridge which is one configuration example of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged detail view of a joint in a bridge axis direction of a precast plate corresponding to a portion X in FIG. 2;

FIG. 4 is a view corresponding to the plan view of FIG. 3 before cast-in-place concrete is poured;

FIG. 5 is a sectional view corresponding to a section taken along line BB of FIG. 4;

FIG. 6 is a partial plan view of a precast plate.

FIG. 7 is a partial plan view showing a retracted state of the dowel.

FIG. 8 is a cross-sectional view corresponding to FIG.

FIG. 9 is a view showing a connection portion of a precast plate in a bridge axis direction.

FIG. 10 is a conceptual configuration diagram of a bridge in which a concrete slab is provided only in a supported portion.

FIG. 11 is a conceptual configuration diagram of a bridge in which the thickness of a concrete slab is changed for each part.

12 is a cross-sectional view corresponding to FIG. 3 of a configuration in which concrete is cast on a precast plate to form a concrete plate having a desired thickness.

13A and 13B are diagrams showing a relationship between a bridge erection method and a bending moment thereof as a conventional example, wherein FIG. 13A is a conceptual diagram of a erection method using a shoring method, and FIG. 13B is a bending moment diagram.

14A and 14B are diagrams showing the relationship between a bridge erection method and a bending moment thereof as a conventional example, wherein FIG. 14A is a conceptual diagram of the overhang erection method and FIG. 14B is a bending moment diagram thereof.

FIG. 15 is a conceptual plan view of a bridge in which a girder height is increased only at a portion supported by a bearing as a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous girder bridge 2 Bridge body 3 Bearing 10 girder 11 Steel girder 11L Lower flange 11W Belt plate 12 Concrete slab 12A Precast slab 12B Cast-in-place concrete 12H Concrete layer (cast-in-place concrete layer) 20 Floor slab 30 Connecting member 31 Horizontal rib ( Horizontal rib member) 32 Dowel (Dowel member)

Claims (6)

[Claims] An I-shaped steel girder extends at least in the axial direction of a pair of bridges to support a floor slab, and a concrete slab is disposed between lower flanges of the adjacent steel girder. A continuous girder bridge, wherein the steel girder and the concrete slab form a box-shaped cross section so that the concrete slab bears compressive stress when a negative bending moment is applied. 2. The continuous girder bridge according to claim 1, wherein the concrete slab is provided only at a portion corresponding to a bearing of the continuous girder bridge on which a negative bending moment acts. 3. The continuous girder bridge according to claim 1, wherein the concrete slab is constituted by a reinforced concrete precast slab erected between lower flanges of the steel girder. 4. The continuous girder bridge according to claim 3, wherein an in-place concrete layer is further formed on the upper side of the precast slab. 5. The concrete plate, wherein the precast plate is erected between lower flanges of the steel girder and fixed by cast-in-place concrete cast between a side end thereof and the steel girder. 5. The continuous girder bridge according to claim 3, wherein a connecting member is provided at a position where the steel girder is buried in the cast-in-place concrete. 6. 6. The connecting member is constituted by providing a horizontal rib member disposed on a web of the steel girder with a dowel member that can be protruded and retracted, and the place is provided with the dowel member protruding. The continuous girder bridge according to claim 5, wherein the continuous girder bridge is buried in cast concrete.