JPH11324345A - Construction method for structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily assemble a form and a reinforcement in constructing a new structure of reinforced concrete construction just under an existing structure in a close state. SOLUTION: An elevatable frame 9 is installed below a temporary girder 3 as an existing structure, and with the frame 9 lowered, a form 10 for forming a floor plate 5 as a new structure is supported thereon by a timbering 11 to be arranged in a lower position than the original installation position. After a reinforcement 12 for forming the floor plate 5 on the form 10 is assembled, the frame 9 is raised by a jack 13 or the like to guide the form 10 and the reinforcement 12 to the original installation position, and concrete is placed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for constructing a structure,
In particular, the present invention relates to a method suitable for application when a new reinforced concrete structure is constructed by being brought close to immediately below an existing structure.

[0002]

2. Description of the Related Art In the field of construction and civil engineering,
In many cases, a new structure is provided close to immediately below an existing structure. For example, a railway viaduct 1 as shown in FIG.
When the vehicle is operated while the existing track is temporarily supported by the temporary columns 2 and the temporary girders 3 as shown in (a), the viaduct 1 may be constructed in the space below the existing track. In such a case, first, pillar 4 of viaduct 1 is erected,
Next, the floor slab 5 is to be provided on the upper part thereof. Generally, the floor slab 5 to be newly installed is provided sufficiently close to the temporary girder 3 which is an existing object. Usually, only a very small gap can be secured between the temporary girder 3 and the temporary girder 3.

[0003]

In the case where a new structure is provided immediately below the existing structure as described above, if the new structure is a reinforced concrete structure, the existing structure is replaced with the new structure. It may hinder construction. For example, in the case shown in FIG. 5, when the viaduct 1 to be newly constructed is a reinforced concrete structure, a concrete casting formwork is provided immediately below the temporary girder 3 when the floor slab 5 is constructed, and the reinforcing steel is placed on the formwork. It is necessary to provide the floor slab 5 close enough to the temporary girder 3, so that there is almost enough space below the temporary girder 3 for formwork and rebar work. And the operation becomes extremely difficult.

For this reason, in the related art, a gap between the floor slab 5 and the temporary girder 3 is made larger than necessary so that formwork and reinforcing work can be performed, or formwork and reinforcing work are not required. There is no other choice but to adopt a simple structure and construction method, but such an inconvenience is inconvenient.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention relates to a method of constructing a structure to be applied when a new reinforced concrete structure is constructed by being brought close to immediately below an existing structure. A frame that can be raised and lowered is installed below the frame, and a frame for forming the new structure is supported on the frame with the support lowered by the shoring while the frame is lowered to a position lower than the original installation position. Place it,
Assembling rebar for forming the new structure on the formwork, and then raising the gantry to guide the formwork and the rebar to the original installation position and cast concrete. I do.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described with reference to FIG. The embodiments described below are:
As shown in FIG. 5, the present invention is applied to a case in which an existing track is temporarily supported by a temporary support 2 and a temporary girder 3 and a reinforced concrete viaduct 1 having a rigid frame structure is newly installed in a space below the temporary support 2 and the temporary girder 3. In this case, the floor slab 5 of the viaduct 1 to be newly installed is required to be provided as close to the temporary girder 3 as possible, and therefore, the space between the floor slab 5 and the temporary girder 3 is about 50 to 150 mm. It is in a situation where only the gap can be secured. 1 to 4, (a) is a cross-sectional view and (b) is a longitudinal cross-sectional view. In this embodiment, as shown in (b), the construction of the viaduct 1 is performed in the length direction. At a fixed length (3 spans in the illustrated example). In addition, in FIGS.
In addition, both the temporary support 2 and the temporary girder 3, which are existing objects, are indicated by chain lines (however, the illustration of the temporary support 2 and the temporary girder 3 is omitted in (b)).

In the construction method according to the present embodiment, first, as shown in FIG. 1, a pile 6 and a foundation 7 for supporting the viaduct 1 are constructed, and only the lower end of the column 4, that is, only the column base 4a is constructed in advance. Then, the column bar 8 is made to protrude above the column base 4a. Since a sufficient space is secured between the temporary girder 3 and the ground surface, these constructions can be performed without any trouble by a normal construction method.

Next, as shown in FIG. 2, a pedestal 9 which can be raised and lowered is provided below the temporary girder 3 on the surface of the ground, and a formwork 10 for forming the floor slab 5 is supported by the support 11 above the gantry 9. And install it. At this time, the gantry 9 is lowered to the surface of the ground, and the height of the shoring 11 is set so that the formwork 10 is at a position lower than the original installation position (that is, the position where the floor slab 5 is to be actually formed). Set. As a result, Shoring 1
The work for assembling the formwork 1 and the formwork 10 can be performed substantially at the surface of the ground and is not a work at a high place, and a work space can be secured below the temporary girder 3 so that the work for assembling the formwork 10 can be easily performed. Can do.

Next, as shown in FIG. 3, a reinforcing bar 12 to be embedded in the floor slab 5 is assembled on the upper part of the formwork 10 assembled above. The work for assembling these reinforcing bars 12 can be carried out without any trouble because a work space is secured between the formwork 10 and the temporary girder 3 because the formwork 10 is located at a position lower than the original installation position.

[0010] When the assembling work of the reinforcing bar 12 is completed,
As shown in FIG. 4, the gantry 9 is gradually raised by using the jack 13, and the reinforcing bar 12 and the formwork 10 are raised to the original installation position, that is, the position where the floor slab 5 is to be formed. Then, while holding the reinforcing bar 12 and the formwork 10 in that position, the column reinforcing bar 14 is assembled in such a manner as to be added to the upper portion of the column base 4a which has already been constructed, and a column formwork (see FIG. Assemble). After that, if the concrete is cast and the floor slab 5 and the pillar 4 are integrally formed, the viaduct 1 as shown in FIG. 5B is completed. In addition, as the jack 13, a general-purpose hydraulic jack, a center hole jack, or the like can be arbitrarily used, and not only a type in which the gantry 9 is pushed up from the surface of the ground but also a type in which the gantry 9 is hung from above. . In addition, the concrete placing load is applied to the jack 1 via the formwork 10, the support 11, and the gantry 9.
3, it is possible to appropriately provide another support between the gantry 9 and the ground surface to receive the concrete placing load.

As described above, by assembling the mold 10 and the reinforcing bar 12 on the gantry 9 at a lower position than the original installation position, and then raising the gantry 9 and disposing it in the original position, The temporary girder 3 does not hinder the work of assembling the frame 10 and the reinforcing bar 12, and the work can be easily performed not on a high place but on the ground surface, and the gantry 9 is jacked up by the jack 13. It is possible to quickly and easily raise the reinforcing bar 12 and the formwork 10 to the original installation position only by using only the temporary girder 3, and there is no hindrance to the operation of the railway temporarily supported by the temporary girder 3.

From the above, according to the above method, the workability can be remarkably improved as compared with the case where the formwork 10 and the reinforcing bar 12 are installed in their original positions from the beginning, It is not necessary to secure an excessively large gap between the temporary girder 3 and the floor slab 5 in consideration of the performance, and a structure which could not be adopted because a work space could not be secured conventionally. The construction method can also be adopted.

The present invention is not limited to the case where the railway viaduct is constructed below the temporary girder as in the above-described embodiment, but is constructed in such a manner that a new reinforced concrete structure is constructed by being brought close to below various existing structures. In this case, the present invention can be widely applied in general, and the form, scale, and use of existing and new structures are not limited at all.

[0014]

As described above, according to the present invention, a frame that can be moved up and down is installed below an existing object, and the formwork and reinforcing bars are lowered to a position lower than the original installation position on the frame. After assembling, the gantry was raised to guide the formwork and rebar to the original installation position and cast concrete, so that the existing work did not become an obstacle when assembling the formwork and rebar. Therefore, workability can be remarkably improved as compared with the case where the formwork and rebar are installed in the original position from the beginning, and as a result, the existing structure and the new structure can be It is not necessary to secure an unnecessarily large gap, and a structure or a construction method that could not be adopted because a work space could not be conventionally secured can be adopted.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment in which a viaduct is constructed immediately below an existing object by a construction method of the present invention, and is a view showing a state in which a foundation and a column base have been pre-constructed.

FIG. 2 is a diagram showing a state where a formwork is installed on a gantry.

FIG. 3 is a diagram showing a state where a reinforcing bar is assembled on a formwork.

FIG. 4 is a view showing a state where the gantry is moved up and down to dispose a formwork and a reinforcing bar at their original positions.

FIG. 5 is a diagram showing an example of a case where a viaduct as a new structure is installed immediately below a temporary girder as an existing object.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Viaduct (new construction) 3 Temporary girder (existing thing) 4 Pillar 5 Floor slab 9 Girder 10 Formwork 11 Shoring 12 Steel bar 13 Jack

Claims (1)

[Claims] When a new reinforced concrete structure is constructed by being brought close to immediately below an existing object, a pedestal that can be raised and lowered is installed below the existing object, and the gantry is lowered onto the pedestal in a state where the pedestal is lowered. A formwork for forming the new structure is supported by a shoring and placed at a position lower than the original installation position, and a reinforcing bar for forming the new structure is assembled on the formwork. A method of constructing a structure, comprising raising the gantry, guiding the formwork and the rebar to the original installation position, and placing concrete.