JPH07310304A - Erection method of concrete arch - Google Patents

Abstract

PURPOSE:To stably and safely erect an arch for supporting bridge floor slabs in a concrete arch bridge without a decrease in the construction efficiency or the safety. CONSTITUTION:A center 3 as a support is constituted of respective centers fabricated in a factory and assembled on a working floor 4 laid on the vertically projected face right below the place where the arch 1 is formed. Forms for defining the arch 1 or prefabricated reinforcements 5 are set on the center 3. Thereafter hanging steel frames 7 erected between abutments 6, between which the arch is formed, are used as reactive bases and the center 3, the forms, and the reinforcements 5 are suspended together right under the position where the arch 1 is formed, while keeping the horizontal posture of the center 3 with a measuring controller. Then concrete is placed in the forms and the reinforcements on the center 3. The hanging steel frames 7 for reaction of the center are utilized as chief members hanging the center 3 on placing concrete. Further, they are buried in the arch 1 to form a SCR-structural arch 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction method used when constructing a concrete arch bridge having small and medium spans, and relates to a construction method of an arch portion provided as a main structure for supporting a bridge deck of an arch bridge. is there.

[0002]

2. Description of the Related Art Conventionally, as the construction method of the arch portion used when constructing a concrete arch bridge of this type, there are (1) ground support method, (2) centle method, (3) steel arch preceding method (synthetic arch method). Four types of construction methods are generally known: construction method and melan method, and (4) lowering method.

To be more specific, first, the ground-type support work of (1) is
This method is applied when constructing a concrete arch bridge between small and medium-sized spans on relatively flat terrain. Then, in this construction method, first, full support is assembled just below the arch portion (arch rib) to be built as the main structure that supports the bridge deck of the arch bridge. After that, the entire supporting structure is used as a scaffold to assemble a formwork and a reinforcing bar for forming the arch part, and concrete is cast into the formwork to form the arch part.

Next, the Centle construction method (2) is a construction method applied when constructing a concrete arch bridge between small and medium-sized spans in a mountain area or a river where it is difficult to apply the above-mentioned ground-type support construction. is there. Then, in this construction method, as shown in FIG. 12, first, an arch-shaped steel centle is assembled immediately below an arch portion (arch rib) to be built as a main structure for supporting a bridge deck of an arch bridge. After that, a mold and a reinforcing bar are assembled and set on the center, and then concrete is cast into the form to form an arch portion.

The center has a two-hinge type arch structure in which the reaction force is placed on the abutment and received by the pin support. In addition, the formed arch portion needs to have self-standing rigidity because the centle material is removed and a vertical material or a stiffening girder is constructed after the concrete of the arch portion is closed.

Next, in the steel arch preceding method (3) (synthetic arch method or melanc method), the arch portion (arch rib), which is the main structure for supporting the bridge deck, is not directly constructed with concrete, It is formed by winding concrete on the arch core material (steel arch) provided in advance.
Then, in this construction method, as shown in FIG. 13, first, an arch core material is completed at a construction position of an arch portion with a steel frame or a steel pipe having a lighter weight than concrete. Thereafter, using a mobile work vehicle or the like, the two arch heads (bridge abutments) are moved toward the arch crown, and the arch core material is wound up with concrete to construct a concrete arch portion.

The features of such a steel arch preceding method are as follows:
Compared to the Pilon construction method and truss construction method, a small temporary member is sufficient. Also, since the arch core material (steel arch) is formed in advance, it is structurally stable when concrete is placed in the arch portion (arch rib), and it is possible to move to and from both banks, which is good workability. It can be mentioned. The above-mentioned arch core material that uses a synthetic member of steel pipe and filled concrete is called the synthetic arch method (see Fig. 13), and the one that uses a steel frame member is called the melanin method (see Fig. 14).

Next, in the lowering method of (4), the arch portion (arch rib), which is the main structure for supporting the deck slab, is roughly divided into two and separately constructed on both abutments (abutments), and then each is There is an arch part that is moved and assembled into an arch shape. Then, in this construction method, as shown in FIG. 15, first, a concrete arch portion (arch rib) is made to extend in the vertical direction, and a climbing foam or the like is used to perform construction on both abutments (abutments). After that, lower the tip of this arch to a predetermined position,
The arch portion is formed by placing concrete of the arch crown portion and closing the arch portion.

[0009]

A major difference between a concrete arch bridge and an ordinary bridge is that the arch portion (arch rib) always has a slope. Therefore,
As long as the construction of the arch portion is a cast-in-place construction method, there is a common point to be noted in that the inclined member is constructed regardless of the difference in each construction method as described in the section of the conventional technique. Therefore, each conventional erection method poses a problem that the construction efficiency is lowered due to the difficulty of construction and the safety is lowered due to the inclination.

Therefore, problems common to the above-described conventional erection construction methods for the arch portion will be described in detail for each step. First of all, regarding the support work, the ground-type support work that supports the reaction force at the time of placing concrete is
It is necessary to have a structurally special function.

That is, in the grounding type supporting work, it is necessary to structurally deal with the horizontal reaction force at the time of pouring concrete, and it is necessary to dispose the reinforcing members such as streaks densely. As a result, there are many opportunities for complicated work in high places, and the possibility of accidents such as falls and falls increases accordingly. It is said that about 30% of industrial accidents in bridge construction are crashes or falls. Therefore, reducing the chances of working at height as much as possible is a fundamental solution to reduce crashes and falls.

Next, the formwork and concrete pouring will be described. In the formwork of the arch part (arch rib), a pressing formwork on the upper surface of the slab is required. In the conventional construction method,
Although a temporary steel material processed into an arch shape is installed and a presser form is attached to it, it takes time to fix the presser form, so it is desired to save labor on site. Also, due to the above-mentioned problem of safe construction, it is necessary to take measures to reduce work at high places as much as possible.

On the other hand, in concrete pouring, even if careful pressing of concrete is carried out in the pressing form part, avatars of air and water are unavoidably generated, which often causes problems of aesthetics and durability. It is desired to use a formwork equipped with a mechanism for discharging excess water and allowing air bubbles to pass through.

Next, as to the assembling of the reinforcing bar, since the assembling work of the reinforcing bar is also carried out on the slope, it is difficult to maintain the shape of the stirrup or the like and the workability is deteriorated. For this reason, it is necessary to reduce the labor of the on-site process by, for example, assembling the pre-fabricated reinforcing bars in advance and installing them on-site.

In addition, since the arch portion (arch rib) has a slope, it cannot be temporarily placed directly on the arch portion. Therefore, a temporary placing table for construction materials (formwork, rebar, etc.) is placed on the arch portion. It is necessary to provide. Therefore, in the stairs where the arch portion is not closed, the temporary load may increase and cause an instability.

[0016] Further, the measurement involved in the construction of the arch portion has a gradient and is inferior in terms of measurement accuracy and efficiency. Therefore, each construction site is devised each time. However, there are many measurement items, and there is a demand for improvement of measurement accuracy and further computerization work such as labor saving and speedup.

The present invention was devised in view of the above-mentioned circumstances, and its purpose is to reduce the construction efficiency and safety of the construction of the arch portion to be built as the main structure for supporting the deck slab of the arch bridge. The purpose of the present invention is to provide a concrete arch erection method that can be carried out reliably in a stable state and can be applied under site conditions where grounding type support work and construction by the Centle method can be performed.

[0018]

The concrete arch erection method of the present invention is positioned as a method that combines the advantages of the above-mentioned conventional Centle method and the melan method of the steel arch preceding method.

The support method according to the present invention has a centr structure, and the centle is a factory-manufactured one, which is vertical projection of the arch portion forming position below the arch portion (arch rib) forming position at the construction site. Assemble on the work floor provided on the surface. In addition, a mold for forming the arch portion and a reinforcing reinforcing bar arranged inside the arch are set on the center assembled on the work floor. In addition, this reinforcing bar is
After attaching the lower formwork of the arch part to the center, prefabricate each construction unit on site and assemble.

After that, the bent suspension steel frame erected between the abutments where the arches are formed is used as a reaction force platform, and a jack provided on the suspension steel frame is used to form the centle and the formwork and reinforcement set on the centle. The reinforcing bars are lifted together with the measurement control device while maintaining the horizontality of the center. In this way, by lifting the center and setting it just below the arch portion forming position, work at high places is reduced.

The attachment of the formwork to the center is performed on the work floor after the center is assembled and before it is lifted by the jack. Also, the presser formwork on the upper part of the formwork, after assembling the upper reinforcement by suspending the center and the lower reinforcement which is the reinforcing bar together,
Attach with a special jig from the suspended steel frame erected on the center. Furthermore, the dismantling of the formwork is done on the work floor after the center is jacked down.

The hanging steel frame for the reaction force of the centle is used not only as a main member for suspending the centle at the time of placing concrete but also embedded in the arch portion (arch rib).
As a result, the arch portion having the SCR structure is formed.

According to the erection method of the present invention as described above, the arch part (arch rib) is formed by assembling the centle on the work floor and by hoisting the formwork and the reinforcing reinforcing bar set on the centle together. It can reduce work opportunities on slopes and high places, and reduce crashes and falls during construction disasters.

Further, by using a prefabricated jig for the formwork and a reinforcing rebar, it is possible to improve the assembling precision of the reinforcing bar and the assembling precision of the formwork and to increase the durability. Further, by suspending the suspended steel frame in advance to form the arch portion, the stress at the time of constructing the arch portion is reliably transmitted to the abutment, and the stability until the arch portion is closed is secured.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The concrete arch construction method of the present invention will be described below with reference to the illustrated embodiments.

At the time of erection of a concrete arch bridge having small and medium spans, the bridge deck 2 of the arch bridge (see FIG. 1).
The construction method of the arch portion 1 (see Fig. 1) provided as a main structure for supporting (f) is to first support the formwork for forming the arch portion and the reinforcing rebars arranged inside the arch. The centle 3 provided directly below the arch portion 1 is assembled on the work floor 4 provided on the vertical projection plane at the arch portion forming position, which is below the arch portion forming position, and the arch portion forming frame is formed on the centle 3. Set the prefabricated reinforcing bar 5 (see (a) in Fig. 1).

Next, the abutment 6 where the arch 1 is formed
In between, the suspended steel frame 7 bent to the same curvature as the arch portion 1
Is assembled and installed in the same shape as the arch part 1 ((b) of FIG. 1)
Together with the jack 8 provided on the hanging steel frame 7, the centre 3 and the formwork and the reinforcing bar 5 set on the centle 3 are maintained by the measurement control device 9 (see FIG. 8) described later while maintaining the levelness of the centle 3. Lift ((c) in Fig. 1)
And (d)).

Next, the formwork and the reinforcing rebars are set in the formwork and the reinforcing bar 5 set on the center 3 so that the hanging steel frame 7 can be taken in. At the same time, the formwork and the reinforcing bar set on the center 3 are set. 5 and the frame of the abutment 6 and the reinforcing steel bars are connected to each other, and the pressing frame 10 is attached to the upper part of the frame in which the hanging steel frame 7 is incorporated by the special jig 11 (see FIG. 4) from the hanging steel frame 7.

After that, while performing measurement by the measurement control device 9, concrete is placed in the form frame in which the suspended steel frame 7 is incorporated and cured for a predetermined period (see (e) in FIG. 1), and after curing, Work floor 4 with the center 3 and the formwork jack 8
By hanging down (see (f) of FIG. 1) and disassembling the center 3 and the form, the arch portion 1 of the SRC structure having the suspended steel frame 7 as a main reinforcing member is formed.

The hanging steel frame 7 may be installed above the position where the arch portion 1 is formed (not shown) so that the arch portion 1 has an RC structure. At this time, a process of removing the suspended steel frame 7 will be added.

Then, the supporting work in this embodiment has a center structure, and each member manufactured in the factory is assembled as a center 1 at the construction site. In addition, a bending steel frame 7 is erected between the abutments 6 on the upper part of the center 1, and a steel hanging material 12 (see FIG. 1 (c)) is attached to the center 1 as a reaction base. Through this hanging steel material 12, a prefabricated member (formwork or reinforcing rebar) 5 is set, a centle 3 is lifted by a jack 8 (hydraulic jack) and set just under the construction position of the arch portion 1, thereby performing work at high places. To reduce

In the center 1 (see FIG. 2), a center beam 3a formed by connecting a plurality of pins at the upper portion and a lower assembly beam 3b at the lower portion are connected in a truss shape by a center column 3c and braces 3d. . In addition, as shown in FIG. 2 (c), the radius of curvature adjusting device 13 is attached to the center strut 1c.
Stranding elastic devices 14 are respectively provided in 3d.

The center 3 has a substantially arcuate shape by means of a center beam 3a formed by connecting a plurality of pins, a radius-of-curvature adjusting device 13 and a striation expansion / contraction device 14.
As a structure that can change the radius of curvature of 3a, it can be diverted to other construction.

The construction cost can be reduced by adopting a structure which can cope with the change of the radius of curvature of the arch portion and can be reused.

3 (a) and 3 (b) show another embodiment of the striation expansion / contraction device 14. As shown in FIG. In this mode, the screw rebar 14a
Is only on one side, and the end portion on the other side is subjected to ring processing so as to be hooked on the hook 14b on one side.

The attachment of the formwork to the center 3 in this embodiment is performed on the work floor 4 after the center 3 is assembled and before being lifted by the jack 8. Further, the presser frame 10 is constructed by hoisting the center 3 and the formwork and the reinforcing bar 5 together, and after assembling the upper bar to the reinforcing bar 5, the special jig 11 from the hanging steel frame 7 erected on the center 3 (Fig. (Refer to 4) to attach to the reinforcing bar 5. Further, the dismantling of the formwork is carried out on the work floor 4 by suspending it together with the center 3 by the jack 8 (see (f) in FIG. 1).

The dedicated jig 11 (see (a) and
(See (b)), a grooved steel form frame fixing girder 11a installed between the suspension steel frames 7, and a form fixing device 11b such as a foam tie, a connecting tool, and both separators provided on the form frame fixing girder 11a. It consists of In FIG. 4, reference numeral 15 is a square steel pipe, and reference numeral 16 is a crosspiece.

In this embodiment, as a countermeasure for avatars on the concrete surface at the time of placing concrete (see FIG. 5), a hollow plastic board 17 (see FIG. 5) having drain holes 17a is formed.
(see (c)) are attached to the weir plate 10a of the presser mold 10 (see (c) of FIG. 5). The arrangement of the face boards 17 is in a state of extending in the bridge axis direction, and the distance between the face boards 17 is set to a pitch that does not reduce the yield strength of the arch portion 1. Then, the surplus water of concrete is discharged from each of the face boards 17 to reduce avatars on the concrete surface.

In order to assemble the reinforcing bar 5 in this embodiment, after attaching the lower formwork for the arch portion 1 to the center 3, as shown in FIG. 6, on the pedestal ((a) and (b in FIG. 6). (See)) for each unit (see (c) in Fig. 6) to make a Brehab, and hang it up on the Centle 3 with a crane to assemble.

In this assembly, a spacer 18 (see FIG. 7) is attached in advance on a form (a weir board), and the prefabricated reinforcing bar 5 (see FIG. 6) is set by a crane,
This is performed by fixing the reinforcing reinforcing bar 5 to the center 3 via the spacer 18. Then, the center 3 and the form and reinforcing bar 5 are integrally lifted by a jack 8 and set at a predetermined position. The spacer 18 is shown in FIG.
As shown in (a) and (b), the P-con 18a is fixed with a foam tie at a predetermined interval, and the spacer body 18b is installed by bending round steel between the P-cons 18a. Has become.

The measurement control by the measurement control device 9 in this embodiment is performed by a sensor in order to secure the displacement and stress of the hanging steel frame 7 which is a reaction force when the centle 3 is lifted and the levelness when the centle is lifted. Hanging (not shown) steel frame 7
And a plurality of jacks 8 are controlled by attaching the jacks 8 to the center 3.

The hanging steel frame 7 for the reaction force of the center 3 is
In addition to being used as a main member for suspending the center 3 at the time of pouring concrete, it is embedded in the arch portion 1 to have the arch portion 1 as an SCR structure. Therefore, it is necessary to measure the displacement and stress of the suspended steel frame 7 and to check the safety while pouring concrete for forming the arch portion 1.

The measurement control device 9 (see FIG. 8) here is
A sensor unit such as a displacement sensor (displacement meter, strain gauge) or a load sensor (load meter) is attached to the center 3 and the hanging steel frame 7 for hanging the center, and an analog signal is extracted from this sensor unit and A / D converted. It is taken in to the computer (personal computer) through the device.

Then, in order to maintain the horizontality of the center 3, the deviation at the displacement sensor position is calculated, and the electromagnetic force in the plurality of jacks 8 supporting the center 3 is kept within the set tolerance. The opening degree of the valve (not shown) is controlled by software (see FIGS. 9, 10 and 11) to secure the safety of the lifting and hanging operations of the center 3.

Even when concrete is poured into the arch portion 1, the suspended steel frame (supporting work) 7 is supported by the measurement control device 9.
Displacement is measured and compared with the theoretical value to verify the validity of the design. In addition, the measurement of FIG. 9, FIG. 10 and FIG.
In the software shown in the control flow chart, the opening of the solenoid valve in the jack 8 can be set to fully open (0%), half open (50%),
It is processed in three stages of fully closed (100%). 9 and 10 here
9 flows from FIG. 9 to FIG. 10, and the software of FIG. 11 shows the control processing at each opening.

The construction of the arch portion 1 which is the main structure for supporting the deck slab 2 of the arch bridge by the construction method of the present invention will be described in the order of steps with reference to the drawings.
As shown in FIG. 1 (a), the construction of the construction yard and the installation of the work floor 4 on the vertical projection plane of the arch 1 construction position are performed, and the center 3 is assembled on the work floor 4. In addition, the center 3 is a curvature radius compatible type in consideration of reutilization (see FIG. 2).

Next, the lower frame for forming the arch portion 1 is assembled on the center and the spacer 18 is fixed to the dam 19 (see FIG. 7). Then, the prefabricated reinforcing steel bars 5 (see FIG. 6 (c)) are carried onto the spacers 18 by a crane and installed, and the prefabricated steel bars are connected and fixed. The reinforcing bar 5 is prefabricated in advance at the nearest temporary yard (see FIG. 6).

Next, the bent suspension steel frame 7 for lifting the center is erected on the center 3 (see FIG. 1B), and the jack 8 is set on the frame 7 on the center 3 (FIG. 1). (See (c)). Also, attach the hanging steel material 12 for lifting the center (see (c) of Fig. 1).

Next, the measurement control unit 9 and the jack 8 are used to set the form 3 and the reinforcing bar 5 in the center 3.
Jack up to a predetermined position while maintaining its horizontality (see (d) in Fig. 1).

Next, after assembling the upper rebar of the arch portion 1 on the upper part of the formwork and the reinforcing bar 5 (see FIG. 6 (d)), the reinforcing bar 5 and the reinforcing bar of the abutment 6 are attached to the formwork and the reinforcing bar 5. To connect. In addition, the presser frame 10 of the inclined portion to which the face plate 17 is attached is attached by the dedicated jig 11. At this time, concrete injection windows and inspection windows (not shown) are provided at several places (see (d) of FIG. 1 and FIG. 5).

Next, the concrete is poured while the measurement is performed by the measurement control device 9 (see (e) in FIG. 1) and cured for a predetermined period. At this time, the suspended steel frame 7 is embedded in the arch portion 1 to form the arch portion 1 as an SRC structure. After that, the jack 8 is lowered to the work floor 4 and the formwork and the center 3 are disassembled. This completes the work of constructing the arch portion 1 which is the main structure for supporting the bridge deck 2 of the arch bridge.

The suspended steel frame 7 can be installed at a position above the arched position of the arch portion 1. By doing so, it is possible to omit the work of assembling the upper reinforcing bar of the arch portion 1 at the installation position (high place) of the arch portion 1. Prefabricated reinforcing bar 5 in this case
Shows the state shown in FIG. 6 (d) from the beginning. And
A process for removing the suspended steel frame 7 is added, and the arch portion 1 has an RC structure.

[0053]

According to the erection method of the present invention, during the erection work of the arch portion, which is the main structure for supporting the deck slab of the arch bridge, the form and reinforcing rebar for forming the arch and the form and reinforcement Assembling with the reinforcing bar support center is done on the work floor installed below the arch formation position, which can reduce work in high places, improve safety in erection work and shorten the process. You can

Reducing this work at high places can reduce the chances of constructing the sloped portion of the arch at high places, and can reduce the number of crashes and falls that occur frequently among construction disasters. Moreover, the introduction of the measurement control device enables real-time construction management such as ensuring safety.

Further, according to the construction method of the present invention, the assembling accuracy of the reinforcing bar and the form can be improved by prefabricating the reinforcing bar and using a dedicated jig for attaching the form such as a pressing form. The durability of the arch portion can be increased.

Further, according to the erection method of the present invention, since the suspension iron frame is erected in advance to form the arch portion, the stress at the time of erection of the arch portion is surely transmitted to the abutment by the suspension steel frame, It is possible to increase the stability of work until the parts are closed.

According to the erection method of the present invention capable of ensuring the safety and improving the construction efficiency as described above, the construction accuracy of the arch portion and the durability performance of the concrete for forming the arch portion are improved. can do.

[Brief description of drawings]

FIG. 1 shows an erection process of an arch portion which is a main structure of an arch bridge, which is carried out by a concrete arch erection method of the present invention, and (a) is a schematic view showing an assembled state of a work floor, a center, a formwork and a reinforcing bar. In the figure, (b) is a schematic diagram showing the assembled state of the suspended steel frame, (c) is a schematic diagram showing the suspended state of the centle with jacks and suspended steel, and (d) is the formwork on the suspended centle and A schematic view showing a state where the formwork and the reinforcing bar are further set on the reinforcing bar, (e)
[Fig. 3] is a schematic view showing a state where concrete is placed in the formwork and reinforcing bars on the center, and (f) is a schematic view showing a state where the center is suspended from the completed arch portion.

FIG. 2 (a) is a schematic view showing a center used in the concrete arch erection method of the present invention, and (b) is a G of (a).
-G line sectional view, (c) is an enlarged view of part A of (a), (d) is
It is a BB line arrow line view of (c).

FIG. 3 (a) is a partially cutaway schematic view showing another embodiment of a stretching device for bracing in a center, and FIG. 3 (b) is a view taken along line CC of FIG. 3 (a).

4A is a schematic view showing a dedicated jig for supporting the upper and lower molds provided on the center, and FIG. 4B is an enlarged view of a portion D of FIG. 4A.

FIG. 5 (a) is a schematic view showing a mounting state of a plastic face plate provided as a countermeasure for avatars, and FIG. 5 (b) is an E-of FIG.
It is a sectional view taken on the line E, and (c) is a schematic perspective view showing a plastic surface.

6 (a) and (b) are schematic perspective views showing a method of prefabricating a reinforcing bar, (c) is a schematic diagram showing a first state of prefabricated reinforcing bar, and (d) is a schematic view. It is a schematic diagram showing the last-stage bar arrangement state of the prefabricated reinforcing bar.

7A is a schematic view showing a spacer for supporting a reinforcing bar fixed in a mold, and FIG. 7B is a sectional view taken along line FF of FIG. 7A.

FIG. 8 is a block diagram showing a measurement control device.

FIG. 9 is a flowchart of measurement and control software in the measurement control device.

FIG. 10 is a flow chart of measurement and control software in the measurement control device.

FIG. 11 is a flowchart of control software in the measurement control device.

FIG. 12 is a process diagram showing a conventional concrete arch construction method.

FIG. 13 is a process diagram showing a conventional method of constructing a concrete arch.

FIG. 14 is a schematic diagram showing a conventional concrete arch construction method.

FIG. 15 is a process diagram showing a conventional concrete arch construction method.

[Explanation of symbols]

1 ... Arch part, 2 ... Bridge deck, 3 ... Centle, 3a ... Centle beam, 3b ... Centle assembly girder, 3c ... Centle column, 3d ...
Streaks 4 ... Work floor, 5 ... Reinforcing bar, 6 ... Abutment, 7 ... Suspended steel frame, 8 ... Jack, 9 ... Measurement control device, 10 ... Pressing form, 10a ... Dam, 11 ... Special jig, 11a ... Formwork fixed girder,
11b ... Form frame fixing device, 12 ... Suspended steel material, 13 ... Curve radius adjusting device, 14 ... Stranding expansion / contraction device, 14a ... Screw rebar, 14b ... Hook, 15 ... Square-shaped steel pipe, 16 ... Pieces, 17 ... Face, 17a … Drainage hole, 18… Spacer, 18a… Pcon, 18b… Spacer body.

Claims (2)

[Claims] 1. A method for constructing an arch portion, which is provided as a main structure for supporting a deck slab of the arch bridge when constructing a concrete arch bridge having small and medium-sized spans. Assemble the center that is provided directly below the arch part to support the frame and the reinforcing reinforcing bar provided inside the arch on the work floor provided on the vertical projection surface below the arch part formation position. At the same time, set the formwork and prefabricated reinforcing bars on this center, and then, between the abutments where the arches are formed, the suspended steel frame bent to the same curvature as the arches has the same shape as the arches. Assembled and erected on the suspension steel frame, and the jacks provided on the hanging steel frame are used to measure the centle and the formwork and reinforcing bars set on the centle using the measurement control device. While maintaining the property, then, in the formwork and reinforcing bar set on the Centle, while further setting the formwork and reinforcing bar to take in the hanging steel frame, the formwork set on the Center and Connect the reinforcing bar and the frame of the abutment and the reinforcing bar, and then attach the presser frame to the upper part of the frame incorporating the hanging steel frame with a dedicated jig from the hanging frame, and then use the measurement control device. While performing the measurement, while placing concrete in the form frame in which the suspended steel frame is taken in and curing for a predetermined period, after curing, suspend the centle and the form frame with a jack to the work floor. A method for constructing a concrete arch, wherein the arch portion having an SRC structure using the suspended steel frame as a main reinforcing member is formed by disassembling. 2. A suspension steel frame is installed above a position where an arch portion is formed so that the arch portion has an RC structure.
The method for constructing a concrete arch according to claim 1, wherein a step of removing the suspended steel frame is added.