JPH0447721B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a construction method for forming a composite girder by combining a reinforced concrete deck slab and a steel girder, for example, when constructing a composite girder bridge.

BACKGROUND ART Conventionally, an example of a composite structural member that has been frequently used is a composite girder in which a reinforced concrete deck slab and a steel girder are combined in a composite girder bridge. This is a structure in which a reinforced concrete deck slab and a steel girder are integrated using connectors such as dowels, so that they jointly resist the subsequent load.

Problems to be Solved by the Invention In the above-mentioned prior art, the steel girder of a composite girder bridge is subjected to vertical loads such as the dead weight of the steel girder, the dead load of the deck slab, the handrail, the pavement, etc., and the live load of people and automobiles. As a result, a positive bending moment acts, compressive stress is generated on the upper edge side of the steel girder, and tensile stress is generated on the lower edge side.
Such stress causes damage such as cracks in composite girder bridges. Therefore, the steel girders and reinforced concrete slabs of such bridges are designed taking into consideration a predetermined tolerance rate for the load. Therefore, the cross section of the steel girder becomes relatively large, and the weight of the steel girder itself also becomes large, resulting in an increase in size. Therefore, there is a problem in that the cost of constructing a bridge is high.

Furthermore, in recent years, cracks in reinforced concrete slabs at road edges have been raised as a major problem in bridge maintenance and management.

The purpose of the present invention is to solve the above-mentioned technical problems,
An object of the present invention is to provide a method for forming a composite structural member, which makes it possible to reduce the weight and size of a steel girder and to improve the cracking strength of a reinforced concrete slab.

Means for Solving the Problems The present invention according to claim 1 provides a composite structural member forming method in which auxiliary members are installed and integrated with a foundation member, comprising: a pair of fixing members spaced apart from each other on the foundation member; is fixed, a plurality of auxiliary members are installed between each fixed member, a jack is interposed between at least one of the fixed members and the auxiliary member, and by stretching this jack, the base member is attached to the base member. A tensile force is generated in the axial direction, and a compressive force is applied to the auxiliary member in the axial direction of the member, and in this state, the auxiliary member is fixed to the base member, and then the jack is contracted. This is a method for forming composite structural members.

The present invention according to claim 2 provides a method for forming a composite structural member in which an auxiliary member is installed and integrated with a foundation member, comprising: fixing a pair of fixing members to the foundation member at a distance from each other; A plurality of intermediate fixing members are fixed at intervals between the fixing members, and an auxiliary member is provided between the pair of fixing members and each intermediate fixing member adjacent to these fixing members, and between each intermediate fixing member. jacks are interposed between the pair of fixing members and the auxiliary member and between each of the intermediate fixing members and the auxiliary member, and by stretching these jacks, the base member is fixed. Applying tensile force in the axial direction of the member,
The composite structural member forming method is characterized in that a compressive force is applied to the auxiliary member in the axial direction of the member, and in this state, the auxiliary member is fixed to the foundation member, and then the jack is contracted.

Effect According to the present invention as set forth in claim 1, a jack is interposed on at least one side between the fixing member and the auxiliary member provided in the base member, and by stretching this jack, the base member A tensile force is introduced and a compressive force is introduced in the auxiliary member. After that, by integrating the foundation member and the auxiliary member, and then loosening the jacking force and removing the jack, tensile stress and bending moment remain in the foundation member, and pressure stress remains in the auxiliary member. do. A composite structural member is thus formed.

According to the present invention as set forth in claim 2, the base member includes:
A pair of fixing members and a plurality of intermediate fixing members are provided at intervals between these fixing members, and a plurality of intermediate fixing members are provided between the pair of fixing members and each intermediate fixing member adjacent thereto, and between each intermediate fixing member. by placing auxiliary members on the respective sides, interposing jacks between the pair of fixing members and the auxiliary member, and between each intermediate fixing member and the auxiliary member, and stretching each jack. , introduces a tensile force into the base member and a compressive force into the auxiliary member.

With this configuration, even when a large number of auxiliary members are laid over a relatively long distance, they can be pressed by the jack without using a jack with a large output. A tensile force can be introduced into the base member as described above, and a compressive force can be introduced into the auxiliary member, without large forces acting on the auxiliary member and the fixing member. Thereby, the base member and the auxiliary member can be integrated without increasing the size of the jack and without increasing the strength of the auxiliary member and the fixing member.

Embodiment FIG. 1 is a side view showing the configuration of a bridge 1 in which the present invention is implemented, and FIG. 2 is a plan view thereof. The bridge 1 is supported by abutments 2 and 3 at both ends.
The bridge 1 includes a plurality of steel girders 4 with an I-shaped cross section extending in the axial direction, and steel members 5 called cross beams or anti-tilt structures supported by these steel girders 4.
It has a skeleton that includes etc. A passage plate 6 is installed on the upper surface of the steel girder 4. The right half of the passage plate 6 is omitted in FIG. 2 for ease of illustration. This passage board 6 is constructed by connecting a plurality of concrete slabs 7.

FIG. 3 is a simplified perspective view of a part of the concrete slab 7 attached to the steel girder 4, and FIG. 4 is a side view seen from the arrow A side in FIG. 3. . The horizontally extending steel girder 4 includes a vertically extending web 9 and an upper flange 10 and a lower flange 11 extending perpendicularly to the web 9 at both ends thereof. A slip prevention member 12 is provided on the upper surface of the upper flange 10 to prevent the concrete floor slab 7, which is an auxiliary member, from slipping. This anti-slip member 12 is, for example, a dowel,
The upper flange 10 consists of a plurality of rod-shaped protrusions 13.
It is melted and fixed on the top surface of the A plurality of these anti-slip members 12 are arranged at intervals on the upper surface of the upper flange 10.

FIG. 5 is a plan view showing an embodiment of the present invention as set forth in claim 1, and FIG. 6 is a sectional view showing the vicinity of both ends of the steel girder 4. Steel girder 4 which is a foundation member
Fixing members 40 and 41 extending perpendicularly to the steel girder 4 are provided at both ends thereof. This fixing member 4
For example, 0 has an L-shaped cross section perpendicular to the axis, and consists of a horizontal part 41a extending in the horizontal direction (perpendicular to the paper surface of FIG. 6) and a vertical part 42a extending in the vertical direction from the end of the horizontal part 41a. Become. This vertical part 42a
is strongly reinforced by a reinforcing plate 43a.
The fixing member 40 is fixed to the steel girder 4 by bolts 44a. A vertical portion 42a of this fixing member 40,
A jack 45 is interposed between the concrete floor slab 7 and the end surface 7a, and this jack 45 is placed on a mounting table 46.

The fixing member 41 provided at the other end of the steel girder 4 also has the same configuration as the fixing member 40, and corresponding parts are given the same numbers with the suffix b. A jack 47 is also interposed between this fixing member 41 and the end surface 7b of the concrete floor slab 7, and this jack 47 is placed on a mounting table 48.

The concrete slab 7 has a plurality of elongated holes 14 in the width direction of the concrete slab 7 (first slots) corresponding to the positions of the protrusions 13 into which the anti-slip members 12 can fit when installed between the steel girders 4. 5).

The process of laying the concrete slab 7 on the steel girder 4 to form the passage board 6 will be described below.

First, the concrete slab 7 is temporarily joined between the steel girders 4 without gaps in the width direction. Thereafter, adhesive is applied or cement mortar or the like is injected or poured into the joint portion 60 (see FIG. 3) of each concrete slab 7 to integrate each concrete slab 7. Next, prestress along the member axis direction of the steel girder 4 of the concrete deck slab 7 is introduced to apply compressive stress to the concrete deck slab 7. To explain specifically,
When jacks 45, 47 operate, jacks 45,
47 piston rods 49, 50 are extended, thereby applying a tensile force to the steel girder 4 and introducing a compressive force to the concrete slab 7. Next, the concrete deck slab 7 into which prestress has been introduced in this manner is integrated with the steel girder 4. Specifically, concrete, cement mortar, or the like is filled into the long holes 14 of the concrete slab 7 and solidified. As a result, the concrete deck slab 7 and the steel girder 4 are fixed to each other and integrated. Thus steel girder 4
and the concrete slab 7 form a composite girder. After combining the concrete slab 7 with the steel girder 4 in this way, each piston rod 49 of the jacks 45, 47,
50 is retracted and the jacks 45, 47 interposed between the fixed plates 40, 41 and the concrete slab 7 are removed.

By such operation, each jack 45, 47
Concrete slab 7 which had been compressed by the force of
tends to extend in the axial direction of the steel girder 4, and the steel girder 4, which has been stretched by the jacks 45 and 47, attempts to contract in the axial direction of the member. However, the concrete slab 7 and the steel girder 4 are integrated,
Since the force of the steel girder 4 to contract and the force to extend the concrete slab 7 are equal, the concrete slab 7 introduced by the jacks 45 and 47 first
The compressive stress and the eccentric tensile force acting on the steel girder 4 will remain as they are. Therefore, a tensile force is introduced into the steel girder 4, causing a negative bending moment to bend the girder upwards. The composite girder according to the present invention has a smaller positive bending moment by this bending moment than a normal composite girder that does not undergo such an operation. As a result, even if a positive bending moment is applied due to a live load such as an automobile or a person, there is sufficient margin up to the allowable bending stress, and it is therefore possible to reduce the cross section of the steel girder. Further, since compressive stress remains in the concrete slab 7, it is very useful for preventing cracks.

FIG. 7 is a plan view showing a concrete floor slab 7 according to another embodiment of the present invention as set forth in claim 1,
FIG. 8 is a partially enlarged perspective view. This concrete floor slab 7 has an uneven surface 21 formed at both ends along its longitudinal direction. This uneven surface 21 has a plurality of recesses 22 formed along its width direction. For example, this concrete floor slab 7
If the width of the recess 22 is 1.5 m, the depth d1 of the recess 22 is 2 cm, and the pitch d2 is 20 cm.
Note that the shape of this uneven surface 21 is not limited to the shape shown in FIG.
Of course, the value of pitch d2 is not limited to this.

Concrete floor slab 7 having such a shape
are arranged on the upper flange 10 of the steel girder 4 so as to face each other at a constant interval. Thereafter, compressive force is introduced into the concrete slab 7 and tensile force is introduced into the steel girder 4 by the jacks 45 and 47, as in the previous embodiment. After that, when integrating the concrete slab 7 with the steel girder 4, the spaces 23 between the mutually opposing uneven surfaces 21 of each concrete slab 7 are filled with a bonding agent such as concrete or cement mortar. By doing so, the concrete deck slab 7 and the steel girder 4 are integrated. The method of loosening the force of the jack and removing it is the same as in the previous embodiment.

In this way, in this embodiment, the concrete floor slab 7
Since the uneven surface 21 is formed on the surface, the concrete deck slab 7 is reliably integrated with the steel girder 4, and therefore, even when the prestress is released, the concrete deck slab 7 will not slide on the steel girder 4. This prevents situations such as being put away.

Figure 9 shows the stress levels of the steel girder 4 and concrete slab 7 when the concrete slab 7 is installed on the steel girder 4 of the embodiment shown in Figures 5 to 8 and prestress is introduced. This is a diagram for explaining,
Fig. 10 is a bending moment diagram corresponding to Fig. 9, and Fig. 11 is a stress diagram in the cross section seen from the cutting plane line This is what is shown. In addition,
In FIG. 9, in order to simplify the explanation, it is assumed that the steel girder 4 is supported at both ends by simple supports 26 and 27. The state in which the steel girder 4 is supported by the fulcrums 26 and 27 is shown in FIG. 91. In this state, the steel girder 4 is subjected to a uniformly distributed load due to its own weight,
A positive bending moment l1 acts, which is represented by a parabola as shown in FIG. The stress state at this time is shown in FIG. 11.

Next, the state in which the concrete slab is attached to the steel girder 4 is shown in FIG. 9, and the bending moment 12 in this state is shown in FIG. 10, 2. This bending moment 12 is the sum of the bending moment 11 shown in FIG. 91 and the bending moment due to the weight of the concrete slab 7. Further, the stress diagram at this time is shown in FIG. 11, 2, and the stress on the upper edge side and the lower edge side of the steel girder 4 is further increased than in the state shown in FIG. 11.

Next, the state in which introduction of the introduction force P is started by the jacks 45 and 47 is shown in FIG. 93.
This introduced force P introduces a tensile force into the steel girder 4 and a compressive force into the concrete slab 7.
Therefore, stress is distributed in the concrete slab 7 and the steel girder 4 as shown in FIG. 11. Note that a negative bending moment l3 shown in FIG. 10 is generated in the steel girder 4. Next, with the introduction force P acting in this way, the concrete slab 7 and the steel girder 4
The state when these are integrated is shown in FIG. 9. When the concrete slab 7 is integrated with the steel girder 4 in this way, the negative bending moment l3 shown in FIG. 10 3 is added to the bending moment l2 shown in FIG. 10 2, and the bending moment shown in FIG. l4 occurs. The stress state at this time is shown in FIG. 11, 4, and is obtained by subtracting the stress due to the bending moment 13 from the stress due to the bending moment 12.

Next, such steel girder 4 and concrete slab 7
In this state, the introduction force P is released by the jacks 45 and 47 as shown in FIG. 9 and 5. As a result, near both ends of the steel girder 4, the concrete slab 7 is released from the compressed state due to the release of the introduction force P of the jacks 45 and 47, as shown in FIG. A positive bending moment l5, designated 5, occurs. The stress state at this time is shown in FIG. 11, 5, and the stress distribution is similar to that in FIG. 11, 4.

By releasing the introduction force P once introduced by the jacks 45 and 47 in this way,
Eccentric tensile force remains in the steel girder 4, and compressive stress remains in the concrete slab 7, resulting in the stress distribution shown in FIG. 11. In addition, in FIG. 9, the bending moment l4 shown in FIG.
, and the bending moment l5 shown in FIG. 10, are added to generate the bending moment l6 shown in FIG. 10, 6. In FIG. 10, the bending moment 13 shown in FIG. 10 is smaller than the bending moment in a normal composite girder, which is shown by the imaginary line l7. In this way, when compared with a normal composite girder, the present invention can reduce the positive bending moment, so it is possible to cancel out and reduce the positive bending moment due to the vertical load, which is taken into account in advance. . In addition, the stress generated in the upper flange 10 and lower flange 11 of the steel girder 4 can be reduced,
In addition, compressive stress can remain in the concrete slab 7, making it possible to prevent cracks in the concrete. Therefore, it is not only possible to reduce the cross section of the steel girder, but also to improve the strength of the concrete slab against cracking, making it possible to construct an economical and highly durable synthetic girder bridge. be.

Normally, a positive bending moment acts on the steel girder part of a composite girder bridge due to vertical loads such as dead loads and live loads of the steel girders, deck slabs, ground covering, handrails, pavement, etc. Compressive stress and tensile stress occur on the lower edge side. In this construction method, tensile force and negative bending moment act on the steel girder, so the compressive stress on the upper edge side and the tensile stress on the lower edge side are both smaller than in normal construction methods. Therefore, it is able to withstand larger loads than normal construction methods. In other words, if we compare the two for the same vertical load, this method requires a smaller cross-sectional area for the steel girder.
Steel girders can be made lighter and smaller. Furthermore, by reducing the cross section of the steel girder, the height of the girder can be lowered, making it possible to reduce loads such as wind pressure applied to the side surfaces of the bridge. Furthermore, it can be applied to places where the space under the girder is limited, and it is economically advantageous by lowering the height of the access road.

In addition, in conventional construction methods, it is necessary to assemble formwork in order to construct reinforced concrete deck slabs, but with this construction method, precast slabs that have been manufactured in advance at a factory etc. can also be used, and in this case, the formwork must be assembled. The number of man-hours required for the construction of the floor slab,
Costs will be reduced.

FIG. 12 is a simplified cross-sectional view of an embodiment of the invention as set forth in claim 2. In this embodiment, a plurality of intermediate fixing members 70 are further fixed between the fixing members 40 and 41 at predetermined fixing positions of the steel girder 4 at intervals. Fixed member 40,
A concrete floor slab 7 is interposed between the concrete floor slabs 7 and the fixing members 40, 41, and 70, and a jack 71 is interposed between the concrete floor slab 7 and the fixing members 40, 41, and 70. Due to the action of this jack 71, compressive stress is applied to the concrete slab 7 and eccentric tensile force is applied to the steel girder 4, as described above.

Effects According to the present invention as set forth in claim 1, when forming a composite structural member, a force is applied in the opposite direction to the compressive force or bending moment generated in the member due to the load considered in the design, so that , it is possible to reduce the weight and size of the member.

According to the second aspect of the present invention, a plurality of intermediate fixing members are fixed to the base member, and auxiliary members are arranged between these intermediate fixing members to be integrated with the base member. Even when the beam length is long, there is no need to use a jack that can exert a large force in order to press many auxiliary members at once, and the structure does not become large. In addition, since there is no need to use a jack that exerts such a large force, the force acting on each auxiliary member and fixing member is small, and therefore there is no need to increase the strength of the auxiliary member and fixing member. This allows auxiliary members to be laid on the base member over long distances without increasing the size and complexity of the construction.

[Brief explanation of drawings]

FIG. 1 is a side view showing the configuration of a bridge 1 in which the present invention is implemented, FIG. 2 is a plan view thereof, and FIG. FIG. 4 is a side view seen from the arrow A side in FIG. 3, FIG. 7 is a sectional view showing the vicinity of both ends of the girder 4, FIG. 7 is a plan view showing a concrete slab 7 of another embodiment of the present invention as set forth in claim 1, and FIG. 8 is a partial view of FIG. 7. The enlarged perspective view, FIG. 9, shows the steel girder 4 and the concrete deck 7 when the concrete deck slab 7 is installed on the steel girder 4 of the embodiment shown in FIGS. 5 to 8 and prestress is introduced. Fig. 10 is a bending moment diagram corresponding to Fig. 9, Fig. 11 is a stress diagram in a cross section seen from the cutting plane line XI-XI in Fig. 9, and Fig. 12 is a claim diagram. 2 is a cross-sectional view of an embodiment of the present invention described in item 2. FIG. 1... Bridge, 4... Steel girder, 7... Concrete deck slab, 7a, 7b... End face, 40, 41, 70...
...fixing member, 45, 47, 71... jack.

Claims (1)

[Claims] 1. In a composite structural member forming method in which auxiliary members are installed and integrated with a foundation member, a pair of fixing members are fixed to the foundation member at intervals, and a plurality of fixing members are fixed between each fixing member. An auxiliary member is installed, a jack is interposed between at least one fixed member and the auxiliary member, and by stretching this jack, a tensile force is generated in the base member in the axial direction of the member, and A method for forming a composite structural member, characterized in that a compressive force is applied to the auxiliary member in the axial direction of the member, the auxiliary member is fixed to the foundation member in this state, and then the jacks are contracted. 2. In a composite structural member forming method in which auxiliary members are installed and integrated with a foundation member, a pair of fixing members are fixed to the foundation member at a distance from each other, and the space between these fixing members is maintained. fixing a plurality of intermediate fixing members with openings; installing auxiliary members between the pair of fixing members and each intermediate fixing member adjacent to these fixing members, and between each intermediate fixing member; and fixing the pair of fixing members. Jacks are interposed between the member and the auxiliary member and between each intermediate fixing member and the auxiliary member, and by stretching these jacks, a tensile force is applied to the base member in the axial direction of the member. let me,
A method for forming a composite structural member, characterized in that a compressive force is applied to the auxiliary member in the axial direction of the member, the auxiliary member is fixed to the foundation member in this state, and then the jack is contracted.