JPH05125705A - Construction of arched concrete by arched form timbering - Google Patents

Abstract

PURPOSE:To raise the resistance against vibration during the placing period of concrete in the construction of arched concrete by using arched form timbering. CONSTITUTION:A timbering A formed by combining semi-arch trusses 3 is set between leg structures 1, and arched concrete is placed on it. In this case, a strong vibration-resistant structure C is projectionally provided to the structures 1 in the direction of the arched concrete up. In the placement of arched concrete by groups, the structure C is first integrally combined, concrete is placed in order for each desired placing section, and finally concrete is placed between the concrete in the section (b1) placed in the first place and the structures 1 in such a way as to bury the structure C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction method for performing arch concrete construction on arch bridges and the like by using arch form supports.

[0002]

2. Description of the Related Art Conventionally, the construction of arch concrete (arch ribs) for arch bridges, etc. has been carried out by the cantilever extension method, the center frame support method, and the pillar type support method, but in recent years it was developed by the present inventor. Construction using arch-shaped frame support (see JP-A-62-1905 as an example) has become popular.

As shown in FIG. 7, the outline of the arch-shaped frame support work is as follows. Half arch trusses 3 and 3 in which the lower ends are pin-coupled 5 to the leg structures 1, 1 such as abutments and piers are mutually apexed. As shown in FIG. 8, the arch-shaped structures a formed by connecting the pins 4 with each other are arranged in a row in the depth direction of the arch concrete B to be constructed (see FIG. 7) at a required interval, and the connecting members 7 are connected to each other. , 7 and diagonal members 8, 8 form an arch-shaped frame support A.

The arch concrete B is formed by placing the mold 6 on the upper surface of the arch-shaped frame support A.
With this concrete, the entire span of the formwork cannot be cast at one time except for a small arch, so the range within which the concrete can be cast at one time is set and the concrete is sequentially cast. In this case, it is very convenient for the construction if the arch concrete is placed by gradually advancing upwards from the sections corresponding to both lowermost ends of the formwork (attachment portions with the leg structure 1). There are problems of inaccuracy of finished shape of art concrete due to large deformation of shoring work, and problem of very large moment generated after hardening of concrete at both bottom ends, and such placing order is taken. You can't do that, and you usually have to hit them.

That is, as shown in FIG. 9, if concrete of b _{1 and} b ₁ at the lower ends (immediately above the lowermost end) of both ends is placed, since the support A is an arch truss structure, Under the load of placing concrete, as shown by the dotted line in FIG. 9, the lower end of the support A bends and bends downward, and the upper part of the support A bends and bends upward accordingly. become. Therefore, the placed concrete is hardened along the deformed shape of the support A. Then, if the concrete is successively struck upward, the placing load of those concretes will cause a new deflection in the support work A, but the deflection due to this will cause the initial placement of the concrete b _1, b _The deflection due to ₁ cannot be corrected significantly. This is because the concrete cast before that is hardened and resists the deformation of the shoring. Therefore, the arch concrete B is formed on the whole in a deformed state close to the bending caused by the initially placed concrete, and it is impossible to form arch-shaped concrete according to the design.

Therefore, in the actual construction, the deformation of the support A due to the concrete pouring is calculated so as to be the smallest, and for example, as shown in FIG. 7, _{first, after the} pouring of b _{1 and} b ₁ , Place concrete in the top section b ₂ ,
In many cases, b ₂ → b _3, b ₃ → b _4, b ₄ → b _5, b ₅ → b
_The concrete is placed in the scattered sections like _6, b ₆ .

Also, arch concrete b at the lowest ends of both sides
Normally, _6, b ₆ (Fig. 1) must be the final placement. This is because, if the concrete cured in a section b _6, b ₆ to concrete is another segment in the presence, with the deformation of the shoring by the load,
This is because an excessive bending moment may be generated in the hardened concrete at the lowermost ends b ₆ and b ₆ and the concrete may be damaged. Therefore, even if the arch concrete is shot up from the bottom to the top, it is necessary to skip the lowermost b ₆ and b ₆ sections and start to pour from b _{1 and} b ₁ .

[0008]

As described above, in pouring arch concrete, not only the concrete pouring for each section is repeated, but also the pouring is done in a scattered manner. Therefore, the partition formwork must be installed and removed each time. From what you need to do
The concrete pouring period will be long. In such a case, in Japan, where there are many earthquakes, it is expected that the supports will be significantly deformed or destroyed during the construction.

It is known that the seismic load at which the arch support A is dangerous is a horizontal load in the width direction of the support A (direction perpendicular to the bridge axis), and other loads are not a problem.
The horizontal load due to an earthquake depends on the seismic coefficient (0, 1
It is a value obtained by multiplying 0, 2), but if concrete in a jumped state is placed on the support A, all the horizontal load of the concrete due to the earthquake must be supported by the support. ..

Even if a small horizontal load is supported by the supporting work, it does not cost much, but at the maximum load, the supporting work requires a very expensive cost to reinforce the supporting work. Maximum horizontal force is when finished out all the concrete, except for the arch two lowermost portion b _6, b ₆ to the final strokes set. At this time, it is assumed that a horizontal load for most of the total weight of arch concrete will be applied in the width direction of the support work, and it will be very expensive to reinforce the support work to withstand this load. I will end up.

Therefore, in order to suppress the generation of the moment, it is necessary to provide an inexpensive earthquake countermeasure for arch support immediately before the lowermost arch parts b _{6 and} b ₆ to be finally placed are placed. Came.

The present invention has been made in view of the above circumstances, and has a problem based on the idea that the horizontal load in the width direction due to the earthquake of concrete is not received by the support work but is received by the hardened concrete itself. It is intended to solve the problem.

[0013]

According to the present invention, arch concrete is continuously cast from both lowermost ends b _{6 and} b ₆ upward, and when they are hardened, the arch concrete becomes a leg structure 1. Since it constitutes a strong cantilever beam that is completely connected to 1, the horizontal load in the width direction due to the earthquake of hardened concrete can be sufficiently endured by this cantilever beam. If the present invention is going launch concrete from the lower end b _1, b ₁ thereon skip lowermost end, the concrete structures of the lowermost end b _6, b ₆ section having the required support strength to earthquakes This cantilever is installed as a part of the cantilever, and a continuous cantilever is formed by filling in this discontinuous part that will be the final placement, and the seismic load is supported by this cantilever and the load given to the support work. Is to reduce significantly. That is, according to the construction method of the present invention, the half arch truss 3, which has an arc shape having a length obtained by dividing the span of the arch concrete B into two, is used.
3, the plurality of arch-shaped structures a, which are connected to each other at the apexes 4, are connected in parallel, and the lower ends of the respective arch-shaped structures a are connected to the leg structures 1 and 1 to form the arch-shaped frame support A. The frame 6 is installed, and the leg structures 1 and 1 are provided with seismic resistant structures C and C that oppose the external force in the width direction of the arch concrete B. It is provided so as to project on both lower end portions, and the initial placement of the arch concrete B is performed by the required length section b ₁ of the lower portion on the arch-shaped frame support A.
To the end of the seismic resistant structure C, and then concrete is spliced between the two initial placing sections b _{1 and} b ₁ mentioned above, and finally, the initial placing section b ₁ and Da設concrete between b ₆ the concrete and the leg structure 1 of, is characterized in that embedded in the seismic structure C in the concrete.

[0014]

The construction method of the present invention is configured as described above, and the concrete in the sections b _{1 and} b ₁ initially placed is integrally connected to the earthquake-resistant structure C, whereby the original equivalent is obtained. The concrete part over the length is the leg structure 1,
The arch concrete B is firmly joined in the width direction. Therefore, when a large horizontal force due to an earthquake is applied during the construction of arch concrete, the concrete part acting as a cantilever will oppose the horizontal force, preventing the deformation and destruction of arch concrete and supporting works. Will contribute to.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. Fig. 1 shows a state in which arch concrete is installed by using arch-shaped frame supports. The arch-shaped form is mounted on the leg structures 1, 1 facing each other such as abutments and mounting bases 2, 2. The lower end of the supporting work (hereinafter referred to as the supporting work) A is framed by pin couplings 5 and 5, a formwork 6 is installed on the upper surface of the supporting work A, and the arch concrete B is formed thereon.

The supporting work A is an arch-shaped structure a formed by pin-joining 4 of two half arch trusses 3, 3 each having an arc shape having a length obtained by substantially dividing the span of the arch concrete B into two at their top ends. A plurality of them are arranged in parallel as shown in FIG. 8 and are connected by connecting members 7, 7 and diagonal members 8, 8. In this support A, the lower end of each arch-shaped structure a is pin-coupled to the mounting bases 2 and 5 to form leg structure 1, 1
A frame 6 is installed on the upper surface of the supporting work A, which is constructed between them.

Further, each leg structure 1 is provided with an earthquake-resistant structure C as shown in FIGS. This structure C
Is an arch concrete B made of H-shaped steel and other bearing rods 9 and 9.
Parallel to each other in the width direction of the
The base end of each load bearing rod 9 is embedded in the concrete when the leg structure 1 is constructed, and the seismic resistant structure C is the lower end of the supporting work A. It is provided so as to project above the section. The connecting rod 10 is provided with a large number of anchor bolts 12 and 12 embedded in the concrete of the arch concrete B which is initially placed and integrally connected.

After the frame of the above-mentioned support work A, the reinforcing bar is placed on the formwork 6.
Arched concrete B after the required reinforcement such as 13, 13
Concrete is poured. In the concrete placing, one placing section (placement range) of concrete is divided into, for example, b ₁ , b ₂ ... b ₆ as shown in FIG. 1 and was at a required interval b _6, that is, concrete is a striking設区between b _1, b ₁ of shoring bottom from connecting rod 10 above the seismic structure C. As a result, the anchor bolts 12 and 12 are embedded in the concrete, and the concrete of section b ₁ and the seismic structure C
And will be rigidly connected together. In this case, although not shown in the drawing, the separator form, the side form, and the outer form required for placing concrete are properly installed.

After the concrete is poured into the initial sections b _{1 and} b ₁ , the concrete is successively poured upward in the subsequent sections b _2, b _3, b _{4 and} b ₅ . Finally, after the reinforcing bar 13 in the concrete is embedded in the leg structure and connected to the protruding reinforcing bar 14, a section b ₆ between the concrete of the initial section b ₁ and the leg structure 1 is joined. Concrete is poured into the concrete, and the earthquake-resistant structure C is buried in the concrete. As a result, the entire arch concrete B is formed. In this way, the last concrete pouring of the section b _{6 in contact} with the leg structure 1 is
Support work A is deformed to some extent by placing concrete,
This is because the arch concrete is also deformed along with it, and it is necessary to eliminate the residual stress (due to the moment) of the arch concrete caused by the deformation.

FIG. 2 shows another embodiment of the present invention, which is more effective in the case of arch concrete having a relatively large span. Also in this example, the concrete pouring section is divided, for example, in the same manner as in the case of the previous example, and in the same manner, the initial concrete pouring is performed in sections b _{1 and} b ₁ connected to the seismic resistant structure C. I do. After that, first, concrete is placed in the section b ₂ which is the top of the support A, and subsequently, the section b _1, b ₁ following the initial placement section b _1, b _1.
3, b ₃ continues on both sides of the section and the top section b ₂ b _4, b ₄ sections,
Then, the concrete is poured into the section b ₅ between the sections b ₃ and b ₄ and finally in the sections b _{6 and} b ₆ between the initial section b ₁ and the leg structure 1. Then, the earthquake-resistant structure C is embedded in the concrete. As a result, the entire arch concrete B can be formed. In the case of this embodiment, the seismic resistance during construction is slightly inferior, but the deformation of the support A is small, and arch concrete almost conforming to the design value can be formed.

The seismic resistant structure C is not limited to that of the embodiment shown in FIGS. The point is to have a structure with high strength and rigidity that can withstand the large horizontal force of the arch concrete B in the width direction. Therefore, various structures other than the structures shown in FIGS. 3 and 4 are possible. For example,
Instead of this, a tensile wire may be stretched obliquely, or the load bearing rods 9 and 9 may be obliquely combined. Then, as shown in FIG. 5, a plurality of seismic resistant structures C may be arranged in the thickness direction of concrete. Further, as shown in FIG. 6, steel plates may be combined and welded to form a hollow box 15, and the hollow box 15 may be combined with the leg rods 16 and 16 embedded in the leg structure 1.

[0022]

As described above, according to the construction method of the present invention, a pair of semi-arch trusses can be joined to form a supporting structure, and a seismic resistant structure is projected on the leg structure. At the tip of the earthquake-resistant structure, the concrete in the initial placement section of arch concrete was integrally connected, and then the concrete was sequentially spliced for each placement section, so an earthquake occurred during the placement of concrete, Even if a large horizontal force is exerted, the placed concrete is integrated with the leg structure through the earthquake-resistant structure, so it is excellent in earthquake resistance, and it is possible to prevent an excessive horizontal force from acting on the support work. It can be suppressed and deformation and destruction due to an earthquake can be prevented. In addition, since it is possible to sequentially pour the arch concrete from the lower part to the upper part, it has an excellent effect such that the workability is remarkably improved.

[Brief description of drawings]

FIG. 1 is a schematic front view showing an embodiment of a construction method of the present invention.

FIG. 2 is a schematic front view showing another embodiment.

FIG. 3 is a plan view showing an embodiment of the earthquake-resistant structure according to the present invention.

FIG. 4 is a front view of the same.

FIG. 5 is a front view showing another embodiment.

FIG. 6 is a plan view showing another embodiment of the present invention.

FIG. 5 is a schematic front view illustrating a conventional construction method.

FIG. 6 is a plan view of supporting work using an arch truss.

FIG. 7 is a modification explanatory view of the support work by partial placement of arch concrete.

[Explanation of symbols]

A arch-shaped frame supporting work B arch concrete a arch-shaped structure b _{1 to} b ₆ concrete placing section C seismic structure 1 leg structure 3 half arch truss 4 pin connection 5 pin connection 6 form 9 load bearing rod 10 connection Material 11 Streaks 12 Anchor bolts 13 and 14 Rebar

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[Procedure amendment]

[Submission date] October 20, 1992

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a schematic front view showing an embodiment of a construction method of the present invention.

FIG. 2 is a schematic front view showing the other embodiment.

FIG. 3 is a plan view showing an embodiment of the earthquake-resistant structure according to the present invention.

FIG. 4 is a front view of the same.

FIG. 5 is a front view showing the other embodiment.

FIG. 6 is a plan view showing another embodiment of the present invention.

FIG. 7 is a schematic front view illustrating a conventional construction method.

FIG. 8 is a plan view of supporting work using an arch truss.

FIG. 9 is a modification explanatory view of the support work by partial placement of arch concrete.

Claims (1)

[Claims] A semi-arch truss with an arcuate length that divides the span of arch concrete into two is joined in parallel to each other, and the lower ends of each arch-like structure are joined to the leg structure. Then, frame the arch formwork support,
A formwork is installed, and a seismic resistant structure that resists the external force in the width direction of arch concrete is provided on the above-mentioned leg structure so as to project on both lower ends of the arch formwork support. The initial pouring of the concrete structure is performed in the required length section on the lower part of the arch-shaped frame support work by connecting it with the tip of the above-mentioned seismic structure. Finally, concrete is placed between the concrete in the initially placed section and the leg structure, and the seismic structure is embedded in the concrete. Construction method of arch concrete by frame support work.