JPH10102423A - Pca form and construction method of pier using the same pca form - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save power and man-hours and shorten a construction period at a construction site and enable the durability of a pier to be enhanced. SOLUTION: PCa forms 20A and 20B are connected in the shape of a square frame by means of a fixture 25 on the ground. The mutually opposed forms PCa forms 20A and 20B are fastened with a separator 26, thereby assembling a PCa form assembly 20 where a tie hoop 27 is incorporated therein. Then this PCa form assembly 20 is hoisted and set up at a pier construction position. A main bar 28a in the inner periphery of a corner area out of a built-in main bar 28 is united with a bonded part on both ends of a shear reinforcing bar preliminarily provided integrally with the PCa forms 20A and 20B so that caste-in place concrete may be placed in the inner side space S of the PCa form assembly 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for constructing a reinforced concrete pier using a precast concrete (hereinafter abbreviated as PCa) formwork.

[0002]

2. Description of the Related Art Conventionally, a pier made of reinforced concrete is constructed by a method as shown in FIGS. 19 to 22, for example. Specifically, in the conventional method, first applying a foundation (footing) 101 ground, thereon successively construction from the first lift 102 ₁ piers 102 by a predetermined execution height to the n lift 102 _n. In the construction of each lift, as shown in FIG. 20, the temporary scaffold 103 is extended and constructed in accordance with the construction height, and the reinforcing bars 10 such as the main reinforcement, the shear reinforcement and the band reinforcement are provided in the pier construction space of the lift.
After lifting and assembling 2a with a crane 104, FIG.
As shown in (1), a form 102b is assembled so as to surround the pier construction space, and concrete is poured into the form 102b. As shown in FIG. 22, the pier 10 by application of up to the n lift 102 _n
When 2 is constructed, a beam portion 105 for erection of a bridge girder is constructed thereon.

[0003]

According to the above conventional method, the following problems are pointed out. (1) Most of the complicated work such as assembling the reinforcing bars 102b such as the main reinforcing bars, the shear reinforcing bars, and the stirrups, and assembling the formwork 102b is performed at a high place, so that it takes time and is dangerous. (1) When assembling the formwork 102b, it is necessary to fasten the formwork 102b with a large number of separators (not shown) in order to counteract the lateral pressure at the time of concrete casting. Take it. (2) It is necessary to dismantle and remove the formwork 102b after the required strength is developed in the concrete. (3) Since the temporary scaffold 103 must be constructed so as to surround the entire circumference of the pier construction space, a lot of temporary materials, labor and time are required.

[0004] The present invention has been made under the above circumstances, and a technical problem thereof is that, in the construction of a pier made of reinforced concrete, labor saving, labor saving, and shortening of the construction period at the site. And to improve the durability of the pier.

[0005]

SUMMARY OF THE INVENTION In order to effectively solve the above-mentioned technical problems, the present invention provides a technique of constructing a pier using a PCa formwork. The PCa formwork used for this pier construction is made of concrete molded P
A Ca weir plate, a plurality of shear reinforcing bars attached to the PCa weir plate so as to extend from the surface on the concrete casting side to the left and right, and arranged on the concrete placing surface And a separator mounting part provided.
(a) At both ends of the shear reinforcement reaching the vicinity of the left and right ends of the weir plate, connecting portions to the bridge pier main reinforcement are formed. In addition,
“PCa” is an abbreviation of “precast concrete” as described above, that is, the PCa dam is a plate-shaped concrete molded product produced in advance in a factory, and “left and right” means the PCa formwork. It refers to a direction that is substantially horizontal when assembled.

The PCa weir plate is a formwork body for forming a pier by cast-in-place concrete, and is integrated with the cast-in-place concrete, which hardens over time after casting, to form an outer wall surface of the pier. It is what becomes. Preferably, a required number of ribs are formed on the surface of the PCa weir plate on the concrete casting side, and the ribs have a reinforcing effect on the PCa weir plate, and are provided with mounting means for shear reinforcing bars and separator mounting portions. Used as a means.

In the construction of a bridge pier according to the present invention, first, the PCa formwork having the above-described configuration is arranged in a rectangular form on the ground, and the ends of the PCa formworks that have been abutted against each other are connected to each other. The PCa molds facing each other are fastened to each other by using
Assemble the formwork assembly. Each PCa formwork constituting the PCa formwork assembly is provided with a shear reinforcement in advance,
Preferably, straps are also incorporated when assembling the PCa formwork assembly on the ground.

Next, the PCa formwork assembly is lifted and installed at a pier construction position, a required number of main reinforcements are installed in the inner space of the PCa formwork assembly, and a part of the main reinforcements is connected to each PCa formwork.
It is connected to both ends of the shear reinforcing bar integrated with the formwork. Then, the cast-in-place concrete is poured into the space inside each of the PCa form assemblies, so that the PCa form of each PCa form is assembled.
a The weir plate is integrated with the cast-in-place concrete over time, and a main reinforcing bar, a shear reinforcing bar, a stirrup, a separator, and the like are embedded and integrated in the cast-in-place concrete.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention when a solid pier 2 is constructed will be described with reference to FIGS. First, FIG. 1 shows that a foundation (footing) 1 is constructed on a ground G, and a first lift 2 _{1 is} placed thereon.
2 shows a process in which a plurality of sets of PCa form assemblies 20 and temporary scaffolds 3 for construction of the above are lifted by the crane 4 and sequentially installed.

As shown in the plan view of FIG. 2, the PCa mold assembly 20 includes a pair of PCa molds 20A having different widths.
20B. Among them, the PCa form 20A is shown in FIG.
As shown in the perspective view of FIG. 1, a PCa dam plate 21 which is a rectangular plate-shaped precast concrete molded body and has three ribs 21 a to 21 c formed on an inner surface serving as a concrete casting side, A large number of shear reinforcing bars 22 which are disposed at appropriate distances and are attached while penetrating the ribs 21a to 21c;
c and insert bolts 23 embedded at predetermined intervals. The PCa dam 21 has a thickness of 50 to 100 mm.
The reinforcing bar 24 is buried in a lattice shape as reinforcing means for preventing cracks or the like at the time of transportation or concreting, or fibers with high tensile strength are mixed. The distance between the inner surface of the PCa dam 21 and the shear reinforcement 22 is set to be equal to or larger than the maximum coarse aggregate size of the concrete in consideration of the concrete filling property at the time of placing the concrete.

The ribs 21a to 21c extend in a substantially vertical direction in the assembled state as the PCa formwork assembly 20, and therefore, the shear reinforcement 22 attached to penetrate it at a right angle is in the assembled state. At a substantially horizontal direction. The left and right ends of the shear reinforcement 22 reach the inside of the left and right ends of the PCa dam plate 21 corresponding to the four corners of the PCa formwork assembly 20, and this portion is bent inward into a substantially J-shape. Thus, a connecting portion 22a is formed.

The width of the PCa frame 20B is larger than the width of the PCa frame 20A, and the four ribs 21d to 21d are provided.
Except that g is formed, it has a structure basically similar to the above.

When assembling the PCa mold assembly 20,
First, on the ground, as shown in FIG.
A and 20B are arranged, and the PCa molds 20A and 20B are connected to each other by a plurality of L-shaped fixing brackets 25 as shown in FIG.
To form a substantially rectangular frame. FIG. 5 shows the details of the connection structure of the PCa molds 20A and 20B by the fixing bracket 25, that is, the fixing bracket 25 is abutted at right angles to the PCa molds 20A and 20A.
Ribs 21a and 21g adjacent to each other near the end of 0B
(And ribs 21c and 21d), these ribs 21a,
It is tightened by an insert bolt 23 embedded in 21g (21c, 21d) and a nut 23a screwed to the insert bolt 23. In this connected state, the PCa formwork 20A, 2A
The connecting portions 22a of the shear reinforcing bars 22 at 0B overlap each other so as to form a substantially U-shape, and this portion is connected to a main bar 28a at a corner described later.

Next, as shown in FIG.
Between the Ca molds 20A, 20A and the PCa molds 20B, 20
B are connected and restrained via the separators 26, and the straps 27 are arranged in a grid pattern so as to extend between the shear reinforcements 22 in the PCa frames 20A and 20B. As shown in detail in FIG. 7, the separator 26 is provided with a turnbuckle portion 26a provided at a central portion in the longitudinal direction.
And an intermediate rib 21b or P in the PCa form 20A.
On the intermediate ribs 21e and 21f in the Ca form 20B,
One having an insert bolt 23 embedded in each of the ribs 21b, 21e, and 21f and metal fittings 26b at both ends tightened by a nut 23a screwed into the insert bolt 23, for restraining between the PCa molds 20A, 20A; Formwork 20
B and 20B are restricted by PCa formwork 20A,
The length is different according to the difference in the width of 20B.

The P framed in a rectangular frame as described above
The Ca-type frame assembly 20, once fried weigh sequentially installed by connecting to the first lifting 2 ₁ construction height by a crane 4,
As shown in FIG. 8 and FIG.
The required number of main bars 28 are erected by the crane 4 in the concrete placing space S defined by. Main bar 28
In the construction work of the
The formwork assembly 20 functions as a kind of safety fence.

The main reinforcement 28 is disposed inside the shear reinforcement 22 in the PCa formwork 20A, 20B, and the main reinforcement 28a built at the corner of the PCa formwork assembly 20 has a substantially U-shape with each other at the corner. As described above, the shear reinforcing bars 22 are passed through the connecting portions 22a of the shear reinforcing bars 22 and connected to each other, whereby the shear reinforcing bars 22 are connected to each other in a substantially rectangular shape. After like an anchor end of the main reinforcement 28 Da設concrete in between the concrete設空, ending the first lift 2 ₁ construction is.

The PCa dam 2 of the PCa formwork 20A, 20B
Reference numeral 1 denotes a concrete product in which the reinforcing bar 24 is buried as described above, which has been transported to the site in a state where shrinkage and drying after molding have been completed, and has high rigidity, and furthermore, the ribs 21a to 21c, Reinforced by 21d to 21g. Therefore, even if the number of the separators 26 for supporting the PCa dam plate 21 from the inside is small as shown in FIGS. 6 and 9, the separator 26 has sufficient resistance to the lateral pressure at the time of casting the cast-in-place concrete.

The PCa dam plate 21 constitutes an outer wall surface of the pier 2 by being integrally joined with cast-in-place concrete whose inner surface hardens with time after casting. 21a-21c, 21d-21g
Since the shear reinforcing bars 22 provided in a state penetrating through serve as a dowel bar, a good joining state is achieved. In order to further improve the bondability with the cast-in-place concrete, it is also effective to form the inner surface of the PCa dam plate 21 into a rough surface.

[0019] after the end of the first lift 2 ₁ of the construction is, to immediately start the construction of the second lift 2 _2. The second lift 2 ₂ construction is constructed by extending the temporary scaffold 3 the execution height, similar to the first lift 2 ₁ construction described above after, PCa ground
Mold 20A, 20B and the separator 26, assembled PCa type frame assembly 20 by hoop 27, and the like, the PCa-type frame assembly 20 sequentially installed to a predetermined height on the first lift 2 ₁ to Agekasane a crane 4, The main bars 28 are erected and concrete is cast. Hereinafter, such a series of steps are repeated until the fifth lift 2 _5, the piers 2 as shown in FIG. 11 is constructed. On the top end of the pier 2, a beam 5 for erection of a bridge girder is constructed.

As described above, the PCa dam 21 (PC
Since the a-forms 20A and 20B) are integrated with the concrete cast therein and become the outer wall of the pier 2, the PCa-forms 20A and 20B do not need to be dismantled / removed. Further, since the PCa formwork assembly 20 is assembled on the ground, the temporary scaffold 3 does not need to be constructed so as to surround the entire circumference of the pier construction position. For example, as shown in the figure, the temporary scaffold 3 is constructed along one side of the pier construction position. Just do it.
In addition, the shear reinforcement 22 is integrated in the inner periphery of the PCa formwork assembly 20 in advance, and the stirrups 27 and the like are installed in a built-in state. And therefore dangerous work at height is significantly reduced.

In the above-described first embodiment, a case where a solid pier is constructed has been described. However, as a second embodiment of the present invention, a case where a hollow pier is constructed will be described.

In this embodiment, as shown in FIG. 18, a PCa formwork assembly 20 comprises an outer frame 20 'made of the same PCa formwork 20A, 20B as in the first embodiment.
And a pair of PCa molds 20 having different widths inside thereof.
C, 20D. The PCa molds 20C, 20D are basically the same as the PCa molds 20A, 20B described in the first embodiment. As shown in the perspective view of FIG. 13, the PCa formwork 20C includes a PCa dam plate 21 'having a single rib 21h formed at the center in the width direction of the outer surface serving as the concrete placing side, and a PCa dam plate. Numerous shear reinforcing bars 22 'attached to the 21' through the ribs 21h.
And insert bolts 23 'buried at predetermined intervals on both left and right ends of the rib 21h and the outer side surface. In the PCa dam plate 21 ', a reinforcing bar 24' is buried in a lattice shape, or fibers having high tensile strength are mixed.

The rib 21h extends in the vertical direction in the assembled state as the PCa formwork assembly 20. Therefore, the shear reinforcement 22 'attached to the rib 21h so as to penetrate it at right angles is horizontal in the assembled state. It extends in the direction as follows. Both ends of the shear reinforcement 22 'reach the inside of the end of the PCa dam plate 21' corresponding to the corner of the inner frame 20 ", and this portion is bent outward in a substantially J-shape. A coupling portion 22a 'is formed.

The width of the PCa mold 20D is the above-mentioned P
The width of the two ribs 21 is larger than the width of the Ca form 20C.
i, 21j are formed, and the others have the same structure as the PCa formwork 20C.

When assembling the PCa mold assembly 20, first, a pair of PCa molds 20C and 20D are arranged on the ground as shown in the plan view of FIG. The inner frame 20 "is assembled by connecting them to each other in a substantially rectangular frame shape through a plurality of L-shaped fixing brackets 25 'as shown in FIGS. 14 and 15. The fixing brackets 25' are perpendicular to each other. Insert bolts 23 'embedded in the ends of the PCa molds 20C and 20D to be abutted against each other and a nut 2 screwed to the insert bolts 23'
It is tied by 3a '. In this connected state,
The joint portions 22a 'of the shear reinforcing bars 22' in the PCa frames 20C and 20D overlap each other so as to form a substantially U-shape, and this portion is joined to a main bar 28b on the outer periphery of a corner portion described later.

Next, PCa frames 20A and 20B are arranged outside the inner frame 20 "formed by the PCa frames 20C and 20D, and the rectangular shape is fixed via the fixing bracket 25 as in the first embodiment. By connecting in a frame shape, the outer frame 2
Assemble 0 '. At this time, the PCa mold 20A having a small width in the outer frame 20 'is parallel to the PCa mold 20C having a small width in the inner frame 20 "and the outer frame 2A.
The PCa mold 20B having a large width at 0 ′ is the inner frame 2.
It is arranged in parallel with the PCa mold 20D having a large width at 0 ".

As described above, the PCa molds 20A, 20A
B outside frame 20 'and PCa molds 20C, 20D
After assembling both of the inner frames 20 "made of PCa, as shown in FIG.
Between the mold 20C and the PCa mold 20B and the PCa mold 2
The outer frame 20 'and the inner frame 20 "are connected to each other by restricting the space between the outer frame 20' and the outer frame 20 'via a separator 26'. Also, the shear reinforcement 22 and the PCa frame 20C in the PCa frames 20A and 20B are connected. , 20D are arranged between the shear reinforcing bars 22 '.

As shown in FIG. 17, the separator 26 'is provided with mounting brackets 26d at both ends of the turnbuckle portion 26c.
, Which is shorter than that used in the first embodiment. That is, this separator 26 'is configured such that the mounting brackets 26d at both ends are connected to the ribs 21b, 21e or 21f of the PCa frames 20A, 20B and the PCa frames 20C, 20C.
D ribs 21h to 21j are tightened by insert bolts 23, 23 'embedded in these ribs and nuts 23a, 23b screwed to the ribs, so that the outer P
Ca formwork 20A, 20B and inner PCa formwork 20C, 2
OD is bridged and mutually supported.

[0029] Once the PCa-type frame assembly 20 assembled in a double rectangular frame shape as described above, was placed the execution height of the first lift to the pier construction location 2 ₁ As shown in FIG. 1, FIG. 1
As shown in FIG. 8, an outer frame 20 'composed of PCa molds 20A and 20B of the PCa mold assembly 20 and a PCa mold 2
A required number of main reinforcing bars 28 are erected in the concrete placing space S between the inner frame 20 "and the inner frame 20" composed of the outer frames 20 ', as shown in FIG.
The main reinforcement 28a, which is erected at regular intervals along the inner periphery of the inner frame and the outer periphery of the inner frame 20 ". The main bars 28a erected at the inner periphery of the corners of the outer frame 20 'overlap each other so as to form a substantially U-shape. The main reinforcement 28b which is passed through the joint 22a of the reinforcement 22 and is built around the corner of the inner frame 20 "is passed through the joint 22a 'of the shear reinforcement 22' which overlaps in a circle with each other. The outer shear reinforcements 22 and the inner shear reinforcements 22 'are connected by the main reinforcement 28a.
Or, they are connected to each other in a substantially rectangular shape via 28b. After the main bars 28 have been built, concrete is poured into the concrete placing space S, and the first lift 2
The construction of ₁ is completed.

[0030] The first lift 2 ₁ after construction completion immediately starts second lift 2 ₂ construction, by repeating the same series of operations as described above, are successively construction hollow piers to a predetermined height go. In this embodiment, the PCa dams 21 of the PCa molds 20A and 20B in the outer frame 20 'are integrated with the cast-in-place concrete whose inner surface hardens with time, so that the outer surface of the pier 2 is joined. PCa form 20 in inner frame 20 "which constitutes the wall
The PCa dam 21 ′ of C and 20D forms the hollow portion wall surface of the pier 2 by being integrally joined with the cast-in-place concrete whose outer surface hardens with time.

The present invention is not construed as being limited to the illustrated embodiment. For example, the number of ribs in the PCa dams 21 and 21 'is appropriately determined according to the cross-sectional area and shape of the pier, the casting height of the cast-in-place concrete, the concrete temperature, the casting speed, and other design conditions. The position at which the main bar 28 is laid and the arrangement of the band bars 27 are appropriately determined according to the above-mentioned conditions. Also,
PCa of PCa formwork 20A, 20B to be the outer wall surface of pier
By forming an appropriate raised pattern or the like on the outer surface of the weir plate 21 during the molding process at the factory, the appearance of the pier can be improved.

[0032]

According to the present invention, the following effects are realized. (1) The use of PCa formwork that is integrated with cast-in-place concrete and becomes the wall of the pier eliminates the need to dismantle and remove the formwork. (2) By using a PCa formwork which is integrated with cast-in-place concrete and serves as a wall portion of a pier, construction can be performed with high accuracy. (3) Since the PCa form can be made to have high rigidity, the number of separators provided to counter lateral pressure at the time of placing concrete can be reduced, and the form can be easily assembled. (4) PCa formwork assembly work using the PCa formwork is performed on the ground, and the PCa formwork assembly is installed in the pier construction space with the separator, the shear reinforcement, the band reinforcement, and the like incorporated therein. Therefore, work at height can be significantly reduced, safety can be improved, and the temporary scaffold can be reduced. (5) For the reasons (1), (3), and (4) above, labor and labor can be saved at the site, and the construction period can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a process of assembling a PCa formwork assembly and a temporary scaffold for construction of a first lift on a foundation in the first embodiment of the present invention.

FIG. 2 is a plan view showing a connecting process of a PCa formwork in the first embodiment.

FIG. 3 is a perspective view showing the PCa mold.

FIG. 4 is a plan view showing a connected state of the PCa formwork in the first embodiment.

FIG. 5 is an explanatory view showing a connection structure of the PCa formwork.

FIG. 6 is a plan view showing an assembled state of the PCa mold assembly according to the first embodiment.

FIG. 7 is an explanatory view showing a support structure of the PCa form assembly by a separator.

FIG. 8 shows the PCa installed in the first embodiment.
It is explanatory drawing which shows the process which builds a main reinforcement in a formwork assembly.

FIG. 9 is a plan view showing a state in which main reinforcing bars are erected in the PCa mold assembly.

FIG. 10 is an explanatory diagram showing a process of assembling a PCa formwork assembly and a temporary scaffold for construction of a second lift in the first embodiment.

FIG. 11 is an explanatory diagram showing a completed construction state of the pier according to the first embodiment.

FIG. 12 is a plan view showing a process of connecting PCa molds to form an inner frame of a PCa mold assembly in the second embodiment of the present invention.

FIG. 13 is a perspective view showing a PCa mold used as the inner frame.

FIG. 14 is an explanatory diagram showing a connection portion of the inner frame in an enlarged manner.

FIG. 15 is a plan view showing an arrangement state of an inner frame and an outer frame of the PCa mold assembly.

FIG. 16 is a plan view showing an assembled state of the PCa mold assembly in the second embodiment.

FIG. 17 is an explanatory view showing a support structure of the inner frame and the outer frame of the PCa frame assembly by a separator.

FIG. 18 is a plan view showing a state where main bars are erected in the PCa formwork assembly.

FIG. 19 is an explanatory view showing a process of constructing a first lift on a foundation in a conventional technique.

FIG. 20 is an explanatory view showing a bar arrangement process of a second lift in a conventional technique.

FIG. 21 is an explanatory view showing a state in which a formwork of a second lift is constructed in a conventional technique.

FIG. 22 is an explanatory view showing a completed state of construction of a bridge pier according to a conventional technique.

[Explanation of symbols]

 2 Bridge Pier 20 PCa Formwork Assembly 20A-20D PCa Formwork 21 PCa Weir Plate 21a-21k Rib 22, 22 'Shear Reinforcement 22a, 22a' Joint 26 Separator 27 Band 28, 28 'Main Bar

Continued on the front page (72) Inventor Masanori Hirano 4-6-115 Sendagaya, Shibuya-ku, Tokyo Inside Fujita Co., Ltd.

Claims (4)

[Claims] 1. A PCa weir plate formed of concrete, a plurality of shear reinforcing bars attached to the PCa weir plate at a position distant from a surface on a concrete casting side and extending in a left-right direction. A separator mounting portion disposed on a surface on the concrete casting side, wherein joint portions to pier main bars are formed at both ends of the shear reinforcement reaching near the left and right ends of the PCa dam plate. PCa formwork. 2. The method according to claim 1, wherein the shear reinforcement is attached via a required number of ribs formed on the surface of the PCa dam plate on the concrete casting side, and the separator attachment portion is formed on the ribs. PCa formwork characterized by the above-mentioned. 3. The PCa formwork according to claim 1 or 2, wherein the PCa formwork is arranged in a rectangular frame shape on the ground and abuts against each other.
Assembling a PCa formwork assembly by connecting ends of the Ca formwork with each other and fastening the PCa formworks facing each other using a separator; and lifting and lifting the PCa formwork assembly at a pier construction position. Installing, installing a required number of main reinforcements in the inner space of the installed PCa formwork assembly, and coupling a part of the main reinforcements to both end joints of the shear reinforcement integrated with each PCa formwork; Casting concrete into the inner space of the PCa formwork assembly. A method for constructing a pier using a PCa formwork, the method comprising: 4. The method for constructing a pier using a PCa formwork according to claim 3, wherein a required number of straps are arranged on the PCa formwork assembly when assembling the PCa formwork assembly.