JP4057724B2 - Support structure of bridge girder in extrusion method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a support structure for a bridge girder used for the purpose of resisting bending stress generated in a bridge girder in an extrusion method generally known as one of construction methods for a prestressed concrete bridge.
[0002]
[Prior art]
As a conventional support structure for this type of bridge girder, for example, a support column standing at the center of a span of a bridge girder to be extruded and one end fixed to the top of the support column, and the other end is fixed. A front diagonal member fixed and stretched at the front part of the bridge girder, and one end fixed to the top of the column, and the other end fixed to the rear part of the bridge girder. There are known ones including a temporary diagonal member made up of a rear diagonal member and a jack that moves the top of the column up and down to adjust the tensile force of the temporary diagonal member.
[0003]
According to such a support structure of the bridge girder, the top of the column is moved up and down using a jack, and a tensile force having a preset value is introduced into the temporary diagonal member, so that a rising force is applied to the cantilever projecting part of the bridge girder. Therefore, it is possible to construct a large span by sequentially extruding bridge girders produced at adjacent production yards from one side using an extrusion device.
[0004]
By the way, the tensile force introduced into the temporary diagonal is changed in the length dimension of the cantilever overhang of the bridge girder, the change in the support position of the bridge girder by the bridge pier, from the temporary diagonal to the main diagonal. Fluctuates sequentially in a complicated manner due to partial replacement of the tensile load. For this reason, in the conventional extrusion construction, the top of the column is moved up and down while measuring and managing the fluctuation of the tensile force of the temporary diagonal member in real time, thereby adjusting the tensile force of the temporary diagonal member.
[0005]
[Problems to be solved by the invention]
However, in the conventional bridge girder support structure, the tensile force of the temporary slanting material fluctuates in a complicated and sequential manner during extrusion construction, and even if it becomes different values before and after and becomes unbalanced, the adjustment of the tensile force only moves up and down the column. This can only be done by the front and rear, so it is practically difficult to eliminate this imbalance, and the cantilever overhangs upward or downward, causing cracks and possibly falling bridges. End up.
[0006]
On the other hand, in the conventional bridge girder support structure, if it is attempted to eliminate such imbalance by using jacks arranged in two rows on the front and rear sides, it is practically impossible to adjust the above-mentioned complicated and sequentially changing tensile force instantaneously and accurately. It is possible, and since a considerable amount of time elapses before such unbalance is eliminated, the possibility of cracking and the failure of a fallen bridge cannot be eliminated.
[0007]
Therefore, the object of the present invention is to support the bridge girder in the extrusion method, in which even if the tensile force of the diagonal member fluctuates in a complicated manner at the time of extrusion construction, it does not become unbalanced before and after, and cracks will not occur and there is no risk of falling bridges. To provide a structure.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the support structure of the bridge girder in the extrusion method according to the present invention includes a column that is erected at the center of the span of the bridge girder to be extruded, a saddle that is provided at the top of the column, and both ends. Each of the portions is fixed to the front and rear in the span direction of the bridge girder, and a diagonal member in which a central portion is slidably stretched with respect to the saddle, and the saddle is moved up and down to pull the diagonal member. seen including a tension adjusting means disposed in a pair before and after adjusting the force, the said saddle is characterized in that it is the lower support suspended before and after by the pair of tension adjusting means.
[0009]
That is, the present invention suspends and supports the front and rear of a bridge girder by a diagonal member slidably stretched with respect to the saddle at the top of the column, and consciously adjusts the tensile force of the diagonal member by the vertical movement of the saddle and the saddle. Even if the tensile force of the diagonal member fluctuates in a complicated manner, the balance is unbalanced by pushing the bridge girder while unconsciously adjusting the tensile force of the diagonal member due to the sliding of the diagonal member. Therefore, the support structure of the bridge girder in the extrusion method is realized without cracking and the possibility of falling bridges.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a side view showing an overall outline of a support structure of a bridge girder in an extrusion method according to an embodiment of the present invention, and FIG. 2 is a front view showing a partial detail in the vicinity of a column of the support structure of the bridge girder in the extrusion method. (FIG. 2a), a side view (FIG. 2b), and FIG. 3 are perspective views showing details of a saddle of a support structure for a bridge girder in the extrusion method.
[0011]
1 and 2, symbol H is a prestressed concrete bridge girder to be extruded, symbol K is a bridge pier that continuously supports the bridge girder H and a bridge girder to be constructed in the future, symbol Y is rebar assembly, concrete A production yard in which the bridge girder H is divided and manufactured by performing the placement of the above, reference numeral D indicates an existing road that is actually in use.
[0012]
Reference numeral 1 denotes a support column erected at the center of the bridge girder H. This is composed of a main tower 1a which is a main installation, and a pyrone column 1b which is a temporary installation integrally provided at the top of the main tower 1a. Note that the bridge girder H according to the present embodiment is used as a highway bridge overpassing the existing road D after the start of operation.
[0013]
Further, reference numeral 2 denotes a saddle provided on the top of the pillar 1b, and reference numeral 3 denotes that both ends are fixed to the front and rear of the bridge girder H in the span direction, and the central part is slid with respect to the saddle 2. A temporary diagonal member stretched freely is shown.
[0014]
Further, reference numeral 4 denotes a lifting jack which is a tensile force adjusting means for adjusting the tensile force of the temporary diagonal member 3 by moving the saddle 2 up and down. This is because a vertical steel member 4b that suspends and supports the saddle 2 by using the fixing tool 4a, a jack body 4c that moves the saddle 2 up and down via the vertical steel member 4b, and the jack at the top of the pillar column 1b. It is comprised from the jack receiving beam 4d which receives and supports the main body 4c.
[0015]
Reference numeral 5 is a hand girder that shortens the substantial length of the cantilever overhanging portion of the bridge girder H and reduces bending stress generated during the extrusion erection, and reference numeral 6 gives an elevating force to the girder girder 5. A temporary horizontal member for reducing bending stress that is sometimes generated, and a reference numeral 7 indicate a diagonal member that is sequentially stretched in the process of pushing and erection of the bridge girder H.
[0016]
In the present embodiment, as shown in FIG. 3, the saddles 2 are arranged in a radial pattern in front and rear, and plate-like members 11 forming a virtual curved surface at the upper end portion, and these plate-like members 11. And a structural member 12 that realizes a tough structure, a vertical steel material 4b that is a constituent element of the lifting jack 4, and a steel pipe 13 that is paired at the front and rear, and a curvature along the virtual curved surface. The tentative slant member 3 is slidably stretched and has a pair of half bent pipes 14 on the left and right sides.
[0017]
Next, the effect | action of the support structure of the bridge in the extrusion method concerning this Embodiment is demonstrated using FIGS. 1-3.
[0018]
First, as a preparatory work, a pillar 1b having a main tower 1a and a saddle 2 at the top is erected in the central part of a branch of a bridge girder H produced while casting concrete in the production yard Y. Then, both end portions of the temporary diagonal member 3 are fixed to the front and rear of the bridge girder H, the central portion is slidably stretched with respect to the saddle 2, and the temporary girder 5 is temporarily installed between the bridge girder H and the hand girder 5. The horizontal member 6 is stretched.
[0019]
Subsequently, on the one hand, when a tensile force having a preset value is introduced to the temporary diagonal member 3, an upward force is given to the cantilever projecting portion of the bridge girder H, and on the other hand, against the temporary horizontal member 6. When a tensile force having a preset value is introduced, a rising force is applied to the hand girders 5. Thereby, the bridge girder H and the hand girder 5 are placed in a state of being stably supported by the support structure of the bridge girder H in the extrusion method according to the present embodiment.
[0020]
In such a state, the bridge girder H is pushed out. That is, while the fluctuation of the tensile force of the temporary diagonal 3 is measured and managed in real time, the bridge girder H is sequentially pushed out from one side using an extrusion device (not shown), and the temporary diagonal 3 is transferred to the permanent diagonal 7. After the replacement of part of the tensile force burden and the process of releasing the tensile force of the main horizontal member after the construction of the hand girders 5 and so on, the construction of the bridge girder H on the existing road D is finally completed. is there.
[0021]
At this time, a change in the length of the cantilever projecting portion of the bridge girder H due to the extrusion construction, a change in the support position of the bridge girder H by the bridge pier K, and a load of tensile force from the temporary diagonal 3 to the main diagonal 7 As a result of partial replacement, etc., the tensile force introduced into the temporary diagonal member 3 changes in a complex and sequential manner. As a result, the tensile force becomes different values before and after, and an imbalance tends to occur.
[0022]
However, in the present embodiment, not only the tensile force of the temporary diagonal member 3 is consciously adjusted by the vertical movement of the saddle 2, but the temporary diagonal member 3 is not affected by the vertical movement of the saddle 2. Since the tensile force slides in a self-correcting manner and the tensile force is unconsciously and instantaneously adjusted, the situation where the tensile force becomes different values before and after and an unbalance occurs is avoided in advance. .
[0023]
Accordingly, according to the present embodiment, the front and rear of the bridge girder H are suspended and supported by the temporary diagonal member 3 slidably stretched around the center of the saddle 2 at the top of the column 1. The bridge girder H can be pushed and installed while performing conscious adjustment and unconscious adjustment of the tensile force in a superimposed manner, so that even if the tensile force of the temporary diagonal member 3 fluctuates sequentially, There is no balance, and the cantilever overhanging portion of the bridge girder H will not bend up or down. Therefore, there is no risk of cracking and, of course, no risk of falling bridges.
[0024]
【The invention's effect】
According to the present invention, since it is configured as described above, even when the tensile force of the diagonal member fluctuates in a complicated manner at the time of extrusion erection, it does not become unbalanced before and after the crack, and the occurrence of cracks and the possibility of falling bridges do not occur. The support structure of the bridge girder in the construction method can be realized.
[Brief description of the drawings]
FIG. 1 is a side view showing an overall outline of a support structure for a bridge girder in an extrusion method according to an embodiment of the present invention.
FIGS. 2A and 2B are a front view and a side view showing details of a portion in the vicinity of a column of a support structure for a bridge girder in an extrusion method according to an embodiment of the present invention. FIGS.
FIG. 3 is a perspective view showing details of a saddle of a support structure for a bridge girder in an extrusion method according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Column 1a ... Main tower 1b ... Pilon pillar 2 ... Saddle 3 ... Temporary diagonal material 4 ... Lifting jack 4a ... Fixing tool 4b ... Vertical steel material 4c ... Jack main body 4d ... Jack receiving beam 5 ... Hand girder 6 ... Temporary horizontal material 7 ... Real diagonal member 11 ... Plate member 12 ... Structural member 13 ... Steel pipe 14 ... Half bent pipe H ... Bridge girder K ... Pier pier Y ... Production yard D ... Existing road

Claims (1)

A column erected at the center of the span of the bridge girder to be extruded, a saddle provided at the top of the column,
An oblique member in which both ends are fixed with respect to the front and rear in the span direction of the bridge girder, and a central portion is slidably stretched with respect to the saddle,
See containing and a tensile force adjusting means disposed in a pair before and after adjusting the tensile force of the diagonal members by moving the saddle in the vertical,
A support structure for a bridge girder in an extrusion method , wherein the saddle is suspended and supported by the pair of tensile force adjusting means in the front-rear direction .

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