JP5620344B2 - Construction method of pier - Google Patents

Description

  The present invention relates to a method for constructing a pier by using a plate-like member made of precast concrete as a mold, and placing the concrete so as to be integrated with the mold made of precast concrete at a construction site.

  As a method for constructing a pier, a method is widely employed in which reinforcing bars are assembled on a formed foundation and concrete is placed in a formwork provided so as to surround them. In this method, the main reinforcing bars arranged up and down from the foundation are raised, the horizontal reinforcing bars that are placed horizontally around the main reinforcing bars to restrain the main reinforcing bars, the intermediate reinforcing bars that connect the reinforcing bars in the horizontal direction, etc. Assemble. Then, a mold is provided so as to surround these reinforcing bars, and concrete is placed in the mold.

Moreover, Patent Document 1 describes a method for building a pier that uses a precast concrete plate as a formwork and casts concrete at a construction site so as to be integrated with these precast concrete plates.
This pier construction method is to construct a pier with a hollow cross-section, using an inner mold frame and an outer mold frame made of precast concrete, and placing concrete between them at a predetermined height. It is to be established. The inner mold frame and the outer mold frame are divided into a plurality of portions in the circumferential direction of the bridge pier, and each of them embeds a band rebar for restraining the main rebar and temporarily supports the main rebar. Then, the inner mold frame and the outer mold frame are arranged so as to be substantially continuous in the circumferential direction on the foundation of the pier or on the already formed portion of the pier. Reinforcing bars attached to adjacent inner formwork or outer formwork connect between adjacent inner formwork or outer formwork, and project the temporarily supported main rebar from the installed pier or foundation below. Join the main rebar. Thereafter, concrete is placed in a space surrounded by the inner mold frame and the outer mold frame, and the inner mold frame, the outer mold frame, the main reinforcing bar, and the belt reinforcing bar are integrated. After the concrete is hardened, the inner and outer formwork are similarly arranged on the top of the hardened pier, and the process of joining the strip reinforcement and main reinforcement and the process of placing concrete are repeated, with the pier standing upwards. It is meant to be built up.

JP-A-8-232212

  However, in the construction method for assembling and joining main reinforcing bars and strip reinforcing bars, assembling the formwork, demolding and removing at the construction site, many operations are performed at the construction site, and the time required for construction becomes long. Further, in order to perform such work, it is necessary to assemble a large scaffold or the like, resulting in poor work efficiency and high cost.

  On the other hand, in the technique described in Patent Document 1, the outer mold frame for forming the outer peripheral surface of the pier and the inner mold frame for forming the hollow inner peripheral surface are opposed to each other at a predetermined interval. In addition to supporting, an intermediate band reinforcing bar having both ends locked to both of the band reinforcing bars embedded therein must be arranged. As shown in FIG. 16, it is desirable to embed the band reinforcement in the inner mold frame 101 and the outer mold frame 102 made of precast concrete in order to improve work efficiency. In this way, the band reinforcement 103 is embedded in the precast concrete. If this is the case, it is necessary to separate the both ends of the intermediate rebars 104 and embed them in the concrete when manufacturing the inner mold 101 and the outer mold 102, respectively. At the construction site, the inner mold frame 101 and the outer mold frame 102 are separately lifted and arranged so as to face each other, and then the intermediate strip reinforcing bar 104 must be connected therebetween. At this time, in order to connect the divided intermediate strip reinforcing bars 104 at one place, it is necessary to accurately match the end faces, which makes the connection difficult. For this reason, as shown in FIG. 16, a short reinforcing bar 106 whose length is adjusted is interposed, and joints 105 are provided at two locations for connection. Therefore, the work amount for connecting the intermediate strip reinforcing bars increases.

  In addition, when the inner and outer molds made of precast concrete are arranged on the site, and when joining the reinforcing bars embedded in the adjacent inner or outer molds, all the mechanical joints are used. It is difficult to accurately match the end faces of the band reinforcing bars protruding from both the inner mold frame and the outer mold frame in order to connect the band reinforcing bars. Furthermore, the connection positions of the strip reinforcing bars arranged in the top and bottom are the same in the axial direction of the strip reinforcing bars. In other words, the connection positions are arranged vertically, which is not desirable for forming a concrete member having no defect.

  The present invention has been made in view of such circumstances, and its purpose is to use a formwork formed of precast concrete, and to efficiently construct a bridge pier having a rectangular cross-sectional shape and having a space inside. It is to provide a construction method.

  In order to solve the above-mentioned problem, the invention according to claim 1 uses a formwork formed of precast concrete, and the concrete placed on site and the formwork are integrated, and the cross-sectional shape is rectangular and inside. A method for constructing a pier having a space, comprising: a precast outer mold frame made of precast concrete having a predetermined height and a plurality of which are arranged in a circumferential direction of the pier to form an outer peripheral surface of the pier; A precast inner mold made of precast concrete which is connected to the precast outer mold at a predetermined interval from the outer mold and forms a hollow inner peripheral surface of the pier, and the precast outer mold and the precast inner A plurality of rebars embedded horizontally in each of the molds, and a rebar and precast inner molds embedded in the precast outer mold A formwork unit having an intermediate rebar that connects the embedded rebar in a horizontal direction is manufactured, and is installed on the foundation of the pier or the already formed part of the pier. A main rebar is inserted between the precast outer formwork and the precast inner formwork to place the formwork unit, and a plurality of formwork units are arranged in the circumferential direction excluding the corners of the pier. Arranging the horizontal reinforcing bars at the corners, and assembling the corner formwork in the field, and in the formwork of the corner and the precast outer formwork and the precast Placing concrete between the formwork, arranging the formwork units, placing the reinforcing bars at the corners, assembling the formwork, and placing the concrete And repeating the process It provides a method for constructing a pier, characterized by launch.

  In this pier construction method, the formwork unit manufactured in advance supports the band reinforcing bar and the intermediate band reinforcing bar that connects the band reinforcing bar in the horizontal direction, so that the bar arrangement work at the construction site is reduced. And the precast inner formwork and the precast outer formwork, which are arranged opposite to each other, are integrally connected, so there is no need to connect the intermediate strip reinforcement at the construction site of the pier, and the formwork is placed at the position where concrete is to be placed. Units can be installed efficiently. Further, in the corner portion, a precast concrete mold is not used, and an open area is provided even after the mold unit is arranged in another part. Then, two adjacent side surfaces of the pier are opened at the corner, and a horizontal reinforcing bar can be efficiently arranged at the corner even if many main reinforcing bars have already been raised. In addition, since the formwork units are installed separately on both sides of the corner, when connecting a plurality of strip reinforcing bars arranged in the vertical direction, the connection positions between the formwork units should be alternately shifted. Can do.

  The invention according to claim 2 is the construction method of a pier according to claim 1, wherein one of the formwork units arranged so as to be adjacent to both sides of the corner portion is excluded from the corner portion. The end of the rebar is protruded horizontally from the substantially vertical end faces of the precast outer mold and the precast inner mold toward the corner, and the other mold unit is The formwork unit and the precast inner formwork have horizontal reinforcing bars projecting horizontally from the substantially vertical end faces toward the corner portion and continuous in a U shape at the corner portion, and the formwork unit. As the horizontal reinforcing bars to be arranged in the corners after the arrangement of the two, two reinforcing bars with hooks having a predetermined length bent at the rear end are hooked and protruded from the end surface of the one mold unit. The band iron Inserting the rebar with the hook from the tip toward the end surface of the protruding rebar along the extension line of the hook, and connecting the rebar with the hook and the end of the rebar protruding from the one formwork unit, A portion bent into a hook shape of the hooked reinforcing bar is embedded and fixed in the corner portion.

  In this construction method, the hooked reinforcing bar can be inserted from the opened corner portion and efficiently connected to the band reinforcing rod whose end protrudes from one mold unit. The hooked reinforcing bars are fixed at the corners, and effectively restrain the displacement of the main reinforcing bars together with the belt reinforcing bars protruding from the other mold unit and bent into a U shape. In addition, the number of joints that connect the reinforcing bars at the construction site can be reduced.

  The invention according to claim 3 is the construction method of the pier according to claim 1, wherein one of the formwork units arranged so as to be adjacent to both sides of the corner portion is excluded from the corner portion. The end of the rebar is protruded horizontally from the substantially vertical end faces of the precast outer mold and the precast inner mold toward the corner, and the other mold unit is The formwork unit and the precast inner formwork have horizontal reinforcing bars projecting horizontally from the substantially vertical end faces toward the corner portion and continuous in a U shape at the corner portion, and the formwork unit. As the horizontal reinforcing bars to be arranged at the corners after the arrangement of the U-shaped reinforcing bars, U-shaped reinforcing bars bent in a U-shape are used, and substantially parallel portions on both sides of the bent portions of the U-shaped reinforcing bars are used. , Said one formwork Inserted toward the end surface of the protruding band reinforcing bar along the extension line of the band reinforcing bar protruding from the end surface of the steel plate, the U-shaped reinforcing bar and the end of the band reinforcing bar protruding from the one formwork unit Are connected to the other formwork unit, and the bent portion of the rebar that protrudes from the other formwork unit and the bent portion of the U-shaped rebar are arranged at the corner portion. The main reinforcing bar should be enclosed.

  In this construction method, the belt reinforcing bars arranged near the outer peripheral surface of the pier at the corner and the belt reinforcing bars arranged near the inner peripheral surface are continuous, and the main reinforcing bars can be effectively restrained. And the U-shaped reinforcing bar can be efficiently connected to the band reinforcing bar whose end protrudes from one of the formwork units, and the position where the joint is provided can be reduced.

  The invention according to claim 4 is the pier construction method according to any one of claims 1 to 3, wherein the precast outer mold frame and the precast inner mold frame are predetermined by a steel truss member. The truss members are in close contact with the precast outer mold frame and the precast inner mold frame, and two string members having an axis in the vertical direction, and a diagonal member for connecting these in an oblique direction. A plurality of anchors fixed to each of the two chord members and embedded in the concrete of the precast outer formwork or the precast inner formwork, the anchors being horizontally arranged at predetermined intervals in the vertical direction Provided in accordance with the vertical spacing of the band reinforcing bars arranged in the frame, and when the mold unit is manufactured, the band reinforcing bars are arranged to be supported by the anchors. To.

  In this pier construction method, when the formwork unit is manufactured, the rebar can be placed with the truss member supported on the truss member, so the rebar can be placed accurately and quickly to efficiently place the formwork unit. It can be manufactured. In addition, it is possible to suppress relative displacement when the precast inner mold frame and the precast outer mold frame are connected by the truss member and are suspended and supported to be arranged at a predetermined position of the constructed pier.

  The invention according to claim 5 is the pier construction method according to any one of claims 1 to 4, wherein the intermediate strip reinforcing bars are provided at predetermined intervals in the horizontal direction, and Are arranged in the vertical direction, and both end portions are embedded in the precast outer mold frame and the precast inner mold frame, and an oblique member having an axis in an oblique direction is brought into contact with the side surface of the band reinforcing bar arranged in the vertical direction. , It is coupled to the plurality of intermediate strip reinforcing bars, and the slanting member restrains the relative displacement between the precast outer mold and the precast inner mold.

  In this method, the precast inner mold frame and the precast outer mold frame are connected by the intermediate band reinforcing bar, and the truss structure is formed by the oblique member, the intermediate band reinforcing bar, the precast inner mold frame, and the precast outer mold frame. Therefore, the precast inner mold frame and the precast outer mold frame can be supported with a simple structure in a state in which relative displacement is suppressed.

As described above, in the method for constructing a pier according to the present invention, it is possible to arrange the reinforcing bar and the intermediate reinforcing bar integrally at a predetermined position on the two plate-like members of the precast concrete arranged opposite to each other. In addition, the work of bar arrangement such as placement and connection of rebars at the construction site, work such as installation and demolding of formwork is reduced, and the pier can be constructed efficiently.
Further, the formwork units can be arranged in a state where the corner portions are opened, and the band reinforcing bars at the corner portions can be inserted almost horizontally from the opened positions to be connected to the band reinforcing bars in the formwork unit. Accordingly, it is possible to efficiently arrange the reinforcing bars and reduce the number of joining points of the reinforcing bars.

It is the schematic side view and elevation sectional view which show an example of the bridge provided with the pier constructed | assembled by the method which concerns on this invention. It is a plane sectional view of the pier shown in FIG. FIG. 3 is a schematic layout diagram of a formwork unit used to construct the pier shown in FIGS. 1 and 2. FIG. 4 is a sectional elevation view of the mold unit shown in FIG. 3. It is a plane sectional view of the formwork unit shown in FIG. It is the elevation sectional view and plane sectional view which expand and show a formwork unit. It is a schematic elevation sectional view and a schematic plane sectional view for explaining a method of manufacturing a mold unit. It is a schematic plane sectional view which shows the method of arrange | positioning a band reinforcement in the corner part of a bridge pier. It is a schematic plan view which shows the method of arrange | positioning a strip reinforcement in the junction part of the long side part of the bridge pier cross-section which became substantially rectangular, and a partition. It is a schematic elevation sectional drawing which shows the other example of the truss member used for a formwork unit, and its function. It is a schematic sectional elevation showing another example of means for suppressing relative displacement of the precast formwork of the formwork unit. It is a general | schematic plane sectional view which shows the other example of the method of arrange | positioning a band reinforcement in the corner part of a bridge pier. It is a general | schematic plane sectional view which shows the other example of the method of arrange | positioning a band reinforcement in the corner part of a bridge pier. It is a schematic plan view which shows the other example of the method of arrange | positioning a band reinforcement in the junction part of the long side part of the bridge pier cross-section which became substantially rectangular shape, and a partition. It is a schematic plan view which shows the other example of the method of arrange | positioning a band reinforcement in the junction part of the long side part of the bridge pier cross-section which became substantially rectangular shape, and a partition. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional elevation view of a precast concrete formwork shown to explain one of the problems to be solved by the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic side view and an elevational sectional view showing an example of a bridge provided with a pier constructed by the method according to the present invention, and FIG. 2 is a plan sectional view of the pier shown in FIG.
This bridge is a three-diameter ramen bridge in which a concrete bridge girder 1 is supported by two piers 2 and two abutments 3.

The pier 2 is made of reinforced concrete and is raised on a caisson 4 formed as a foundation or a footing 5 formed as a direct foundation. The cross-sectional shape of the pier is substantially rectangular as shown in FIG. 2 and has a hollow cross section with a space inside, and a partition wall that divides the hollow portion into two is provided.
Main rebars 11 and 12 are arranged in a vertical direction at a position along the outer peripheral surface and a position along the inner peripheral surface in the cross section of the pier 2, and outside the main rebar 11 arranged at a position along the outer peripheral surface. That is, on the outer peripheral surface side, the horizontal reinforcing bars 13 are arranged at a predetermined interval in the vertical direction. Moreover, the belt reinforcement 14 is arrange | positioned also at the internal peripheral surface side of the main reinforcement 12 arrange | positioned in the position along an internal peripheral surface. When these strip reinforcing bars 13 and 14 generate a large bending moment in the pier 2 and a compressive stress is applied to the main reinforcing bars 11 and 12 after a tensile stress close to the yield point stress or a tensile stress exceeding the yield point stress is generated. The main reinforcing bars 11 and 12 are arranged to restrain the buckling and swelling from the surface of the concrete member. And both ends are latched by the band reinforcement 13 arrange | positioned along an outer peripheral surface, and the band reinforcement 14 arrange | positioned along an inner peripheral surface, and restrains that a band reinforcement is extruded to the surface side of a concrete member. The intermediate rebars 15 are arranged with respect to all of the rebars 13 and 14 arranged in the vertical direction at a predetermined interval in the horizontal direction.

  The pier 2 is constructed by repeating the installation of the formwork, the arrangement of the reinforcing bars, and the placement of the concrete for each construction section set in advance to a predetermined height. And the plate-shaped member formed with precast concrete is used for a formwork as an outer formwork and an inner formwork, and these are used in combination with a metal form or a plywood formwork assembled at a construction site. The precast concrete formwork is integrated with the concrete cast on site and becomes part of the pier.

As shown in FIG. 3, the formwork formed of precast concrete excludes the corner portion 2a of the cross section which is rectangular, and is provided on the outer peripheral surface portion and inner peripheral surface portion between the corner portions and both side surface portions of the partition wall. Used.
The precast concrete formwork used for the long side portion of the cross section which has become almost rectangular and the precast concrete formwork used for the short side portion form the inner peripheral surface with the precast outer mold frames 16 and 18 forming the outer peripheral surface. a precast inner die frame 17, 19 which is connected by a steel truss members 21, respectively a mold unit U _B formwork units U _a or B type a type. Even when these formwork units are lifted, the relative displacement between the precast outer formwork and the precast inner formwork is suppressed by the steel truss member 21, and they are lifted in an integrated state. It can be installed at a predetermined position.

  The truss member 21 is made of steel, and as shown in FIG. 4, the first chord material 21a that comes into contact with the concrete of the precast outer molds 16 and 18 and the second chord that comes into contact with the concrete of the precast inner molds 17 and 19 are used. It has a string material 21b and is connected by an oblique material 21c so that they are substantially parallel to each other. For the first chord member 21a and the second chord member 21b, a steel plate such as H-shaped steel or L-shaped steel can be used, and for the diagonal member, L-shaped steel or steel plate can be used. Further, the first chord member 21a and the second chord member 21b are attached so that a plurality of anchors 21d protrude from the surfaces of the precast outer mold frames 16 and 18 and the precast inner mold frames 17 and 19 in contact with the concrete. The precast outer molds 16 and 18 or the precast inner molds 17 and 19 are embedded in the concrete.

On the other hand, as shown in FIG. 3, the precast concrete precast mold 20 used for the partition wall portion similarly has a first precast mold 20a that forms one elevation surface and a second precast mold frame 20a that forms the other elevation surface. The precast mold 20b is connected by a truss member 21 to form a C type mold unit U _C that can be installed as a unit.

As shown in FIG. 3, the A-type mold unit U _A used for the long side portion of the cross-section that is substantially rectangular is, as shown in FIG. 3, from one corner portion adjacent to the precast outer mold frame 16 to the other corner portion. One precast concrete plate is formed in the vicinity, and the precast inner mold 17 facing the same is divided into two, and the divided precast inner mold 17 is substantially the same virtual space with a predetermined interval between each other. It is arranged on the surface. A partition wall is provided in an open portion between the two precast inner molds 17.

  In the precast outer mold 16 and the precast inner mold 17, as shown in FIG. 5 (a), band reinforcing bars 13 and 14 are embedded horizontally along the outer peripheral surface or the inner peripheral surface, respectively, and at predetermined intervals in the vertical direction. Is opened and placed in the entire area in the height direction. The rebar 13 embedded in the precast outer mold 16 is exposed from one end surface 16a in the horizontal direction of the precast outer mold 16, is bent in a U shape, and is one end surface 17a of the precast inner mold 17. It is continuous with the belt rebar 14 protruding from. From the other end surfaces 16b and 17b of the precast outer mold 16 and the precast inner mold 17, band reinforcing bars 13 and 14 respectively protrude with a predetermined length. Further, from the open part between the precast inner mold 17 divided into two sheets, a reinforcing bar 22 whose tip is locked to the band reinforcing bar 13 of the precast outer mold 16 is the surface of the precast inner mold 17. And protruding almost vertically.

  Further, as shown in FIG. 6, both ends of the intermediate rebar 15 are locked to the rebar 13 embedded in the precast outer mold 16 and the rebar 14 embedded in the precast inner mold 17, respectively. Plates 15a made of steel are welded or heated and pressurized and pressed against both sides of the intermediate rebar 15 and the plate 15a is brought into contact with the side surfaces of the rebars 13 and 14 so as to contact the intermediate rebar 15 and the plate 15a. Is hung around the steel bars 13 and 14 and locked. Then, both ends of the intermediate rebar 15 are embedded in the concrete to be the precast outer mold 16 or the precast inner mold 17 together with the rebars 13 and 14 by placing concrete, and the two precast molds are between the two ends. It is exposed between.

Substantially rectangular and become formwork units U _B of B type used in the shorter side portion of the cross-section, as shown in FIG. 5 (b), and precast outer frame 18 and the precast inner die frame 19 are opposed, truss The members 21 are connected. And the band rebars 13 and 14 are arrange | positioned at each of the precast outer formwork 18 and the precast inner formwork 19, and the intermediate | middle belt reinforcement 15 is arrange | positioned so that these may be connected. Similarly to the _A- type formwork unit U _A , the band rebar 13 protruding from the end surface 18a of the precast outer formwork 18 is bent into a U shape at one end in the horizontal direction, and the precast inner formwork 19 It is continuous with the belt reinforcing bar 14 protruding from the end face 19a. At the other end, strip reinforcing bars 13 and 14 of a predetermined length protrude from the end face 18b of the precast outer mold and the end face 19b of the precast inner mold, respectively.

As shown in FIG. 5 (c), the C type mold unit U _C used for the partition wall portion has two precast molds 20a, 20b facing each other with a predetermined interval, and these are the truss members 21. Are connected to each other. Moreover, the band reinforcement 23 and the intermediate band reinforcement 15 are arrange | positioned at each precast formwork 20a, 20b, and the band reinforcement 23 from each of the 1st precast formwork 20a and the 2nd precast formwork 20b from the end surface in a horizontal direction. Is sticking out.

The above-mentioned formwork unit can be manufactured as follows in a factory or a manufacturing yard. FIG. 7 is a schematic elevational sectional view and a schematic plan sectional view showing a state in which reinforcing bars are arranged in order to manufacture a formwork unit and the formwork is installed.
First, the truss member 21 is installed on the production base 31 of the formwork units U _A and U _B. Then, the reinforcing bars 13 and 14 embedded in the precast outer molds 16 and 18 and the precast inner molds 17 and 19 are arranged. Hoop reinforcement 13 is placed horizontally, vertically formwork unit a plurality of hoop reinforcement at predetermined intervals in U _A, arranged in substantially the entire height direction of the U _B. These band reinforcing bars 13 and 14 are provided with an assembly bar at an appropriate interval in a substantially vertical direction, and are supported by these. Further, the truss member 21 may be supported.
When the band reinforcing bars 13 and 14 are arranged, both ends are locked to the band reinforcing bar 13 embedded in the precast outer mold frames 16 and 18 and the band reinforcing bar 14 embedded in the precast inner mold frames 17 and 19, and the intermediate band reinforcing bar 15 is horizontally disposed. To place. The intermediate rebar 15 is locked to the rebars 13 and 14 between the opposing positions so that the axis is substantially perpendicular to the precast outer molds 16 and 18 and the precast inner molds 17 and 19. And all the strip reinforcing bars 13 and 14 arranged in the up-and-down direction are provided in the same position, and a plurality is arranged up and down. Further, these intermediate strip reinforcing bars 15 are provided at a plurality of positions in the horizontal direction at predetermined intervals, and when the pier is completed, the strip reinforcing bars 13 and 14 can be restrained from being pushed out to the surface side of the concrete member.

When the band reinforcing bars 13 and 14 and the intermediate band reinforcing bar 15 are arranged, the formwork for placing the concrete of the precast outer molds 16 and 18 and the precast inner molds 17 and 19 on both sides of the band reinforcing bars 13 and 14 is provided. Is provided. The inner formwork 32 that forms a surface that comes into contact with the concrete placed at the construction site of the pier is abutted against the first chord member 21a and the second chord member 21b of the truss member 21, and the intermediate band reinforcing bar 15 Is provided so as to penetrate. In addition, an outer mold 33 is provided which faces the inner mold 32 and forms an outer peripheral surface or an inner peripheral surface of a concrete member serving as a pier. Then, concrete is placed between the outer mold frame 33 and the inner mold frame 32 to embed both ends of the band reinforcing bars 13 and 14 and the intermediate band reinforcing bar 15, and the two string members 21 a of the truss member 21. , 21b protruding from the anchor 21d. Thereby, the formwork units U _A and U _B provided with the precast outer molds 16 and 18 and the precast inner molds 17 and 19 connected by the intermediate band reinforcing bar 15 and the truss member 21 are completed.
Note that the mold unit U _C C-type arrangement of the first precast mold 20a and hoop reinforcement 23 embedded in the second precast mold 20b, the arrangement of the intermediate band rebar 15, the inner and outer mold the pouring of the formation and concrete similarly performed on, it is possible to manufacture the mold unit U _C of C type.

Next, a method for constructing the pier 2 using the above-mentioned formwork units U _A , U _B , U _C will be described.
The base caisson 4 or footing 5 is formed, and the lower ends of the main reinforcing bars 11 and 12 of the pier 2 are embedded in the caisson 4 or footing 5 and protrude upward. The 1st construction division of the lower end part of the pier 2 is built in the part where these main reinforcing bars 11 and 12 were started. The portion 2b in which the concrete member thickness at the lower part of the pier 2 shown in FIG. 1B is enlarged, that is, the portion where the inner peripheral surface is tapered is assembled at the construction site by rebar assembly and formwork assembly. To cast. That is, the band reinforcing bar 13 surrounding the main reinforcing bars 11 and 12 and the band reinforcing bar 14 along the inner peripheral surface are arranged, and the intermediate band reinforcing bar 15 is arranged. Then, an outer mold frame for forming the outer peripheral surface, an inner mold frame for forming the inner peripheral surface, and a mold frame for forming the partition wall are installed, and the concrete is placed in a range surrounded by these mold frames. To cast.

When the first construction section at the lower end of the pier is constructed, as shown in FIG. 6, the formwork units U _A , U _B , U _C formed in advance on the already formed part 2e of the pier are replaced. Deploy. The formwork units U _A , U _B , and U _C are lifted by a crane or the like, and are already set up between two precast concrete formwork connected almost in parallel by the truss member 21 and the intermediate strip rebar 15. Reinforcing bars 11 and 12 are installed. Mold units for one construction segment, two mold units U _A A type, two mold units U _B of B type, and one C-type formwork unit U _C, Figure 3 Arrange as shown. These formwork units U _A , U _B , and U _C have almost the same height and the height of one construction section. The A type is on the long side of the cross-sectional shape that is almost rectangular, and the B type is on the short side. In addition, the C type is disposed in the partition wall portion, and an open region is provided with a space between the mold unit at the corner 2a of the cross section and the joint portion 2f between the long side portion and the partition wall portion.

In the A portion shown in corners 2a of clogging Figure 2 above section, as shown in FIG. 8, either one (Figure of mold units of adjacent A-type U _A and B type mold unit U _B U _B) is an 8 example, the hoop 13 from precast outer frame 18 and the precast within mold 19. protrude, they are continuous in a U-shape. And it arrange | positions so that the part 13b bent in the U-shape may become a position along the outer peripheral surface of the corner part 2a. Further, (U _A in the example of FIG. 8) the other mold units, predetermined length horizontally該隅angle end of the precast outer frame 16 and the precast inner mold frame 17, respectively zone from the Metropolitan rebar 13 It arrange | positions so that it may protrude toward the part 2a.

  A U-shaped reinforcing bar 24 bent in a U-shape as shown in FIG. 8 is connected to the band reinforcing bars 13a and 14a that protrude horizontally by a predetermined length. The U-shaped reinforcing bar 24 supports the straight portions 24a and 24b which are U-shaped bent and substantially parallel to each other on the extension line of the band reinforcing bars 13a and 14a protruding horizontally, and along the extension line. It is inserted from the corner portion toward the end faces of the band reinforcing bars 13a and 14a. By inserting the U-shaped reinforcing bar 24 in this way, even if a plurality of main reinforcing bars 11 and 12 are erected at the corner 2a, the end face is projected from the formwork unit without being obstructed by them. It can face | match with the end surface of the reinforcing bars 13a and 14a. At this time, the bent part of the U-shaped reinforcing bar 24 is arranged along the outer peripheral surface at the corner 2a of the pier cross section, and the band reinforcing bars 13a and 14a protruding horizontally from the U-shaped reinforcing bar 24, Connect. This connection work can be performed in an open area between adjacent formwork units.

The U-shaped reinforcing bars 24 and mold unit U _A hoop projecting horizontally from 13a, the 14a, both a so-called deformed bars, that in these connections using joint grout expression desired. That is, the end part of the reinforcing bar connected from both ends is inserted inside the tubular member made of steel, and a mortar or synthetic resin grout is injected into the tubular member and cured. Further, a full threaded steel bar having a thread on the outer peripheral surface of the deformed reinforcing bar is used, and the U-shaped reinforcing bar 24 and the formwork unit U _{A are connected} to each other by a long nut-like mechanical joint 25 screwed onto the thread. The protruding band reinforcing bars 13a and 14a can also be connected. Furthermore, the joint of another aspect can also be used as long as it does not lose the function of the rebar.

  Thus, the rebar 13b protruding from one mold unit and bent in a U shape, and the U rebar 24 connected to the rebars 13a and 14a protruding horizontally from the other mold unit are provided. The corner bars 2a are overlapped with each other and surround the main reinforcing bars 11 and 12 disposed in the corner section 2a. These reinforcing bars are band reinforcing bars, and the main reinforcing bars 11 and 12 are the corner bars 2a. Extrusion from the concrete to the outer peripheral surface side can be restrained.

In this embodiment, the position of the end face of hoop 13a, a predetermined length of 14a projecting horizontally above form unit U _A is set to a position shifted in a direction along the sides of the piers section Yes. That is, the end face of the precast outer mold 16 is set at a position farther from the corner 2 a than the precast inner mold 17. And the length of the some rebar 13a protruded from the end surface of the precast outer formwork 16 is arranged so that a long thing and a short thing may alternate up and down. The lengths of the straight portions 24a of the U-shaped reinforcing bars connected to the horizontally protruding band reinforcing bars 13a are alternately adjusted so as to correspond to the protruding lengths of the band reinforcing bars 13a, and the joint positions of the band reinforcing bars 13a are adjusted. It is possible to avoid having the same position in the horizontal direction in all of the strip reinforcing bars 13 arranged vertically. In other words, the joint positions of the band reinforcing bars 13a are alternately shifted horizontally, so that the reliability of the reinforcing bars is improved and uniform concrete can be placed. On the other hand, the joint of the band rebar 14a at the position along the inner peripheral surface of the pier cross section is provided at a position close to the corner 2a and is the same position in the horizontal direction, but the joint of the band rebar along the outer peripheral surface. Similarly to the above, the position of the end face of the precast inner mold 17 can be set to a position away from the corner 2a, and the position of the joint can be alternately shifted.
Further, the positions of the end faces of both the precast outer mold 16 and the precast inner mold 17 are set close to the corners 2a, and the joints are the same for all of the strip reinforcing bars 13 and 14 arranged in the upper and lower directions. It can also be made to be. Thus, by setting the positions of the end faces of the precast outer mold 16 and the precast inner mold 17 close to the corner 2a, the area of the mold assembled at the construction site of the pier can be reduced.

The portion B shown in FIG. 2, that is, the portion where the long side portion of the cross section of the pier that is substantially rectangular and the partition wall is joined, as shown in FIG. 9, is the precast inner formwork 17 of the _A type formwork unit UA. The end face of the precast mold 20 provided in the C-type mold unit U _C is arranged at a portion where the gap is interrupted so as to face each other with a gap. At this time, a predetermined length of the band rebar 23 protrudes horizontally from the end surface of the precast formwork 20 included in the _C type formwork unit UC. The end face of the rebar 23 is opposed to the end face of the reinforcing bar 22 protruding from the portion where the precast inner form 17 of the _A type formwork unit UA is interrupted. As shown in FIG. 9, reinforcing bars 26 cut in accordance with these intervals are interposed between the end faces of these reinforcing bars 22 and 23, and both ends of the reinforcing bars 22 protrude from the _A type formwork unit UA. And a band rebar 23 protruding from the _C- type formwork unit U _C by a joint 25. After that, the intermediate band reinforcing bar 15 is arranged at this connecting portion. This intermediate band reinforcing bar 15 is also a plate fixing type intermediate band reinforcing bar with a plate 15a fixed to the end thereof, and is arranged for all of the band reinforcing bars 23 arranged in a plurality in the vertical direction.

Thus, by utilizing the open portion between arrayed mold unit, to the junction 2f of mold units U _C formwork units U _A and C type of each corner portion 2a and A-type When the bar arrangement is completed, a mold (not shown) is installed in each of these open portions.
After that, concrete is cast in these molds, between the precast outer molds 16 and 18 and the precast inner molds 17 and 19, and between the two precast molds 20a and 20b of the partition wall, and the exposed band. The reinforcing bars 13, 14, the intermediate band reinforcing bars 15, the main reinforcing bars 11, 12, the truss member 21, etc. are embedded and brought into close contact with the precast molds 16, 17, 18, 19, 20. As the concrete hardens, the necessary reinforcing bars are embedded and one construction section of the pier that is integrated with the precast concrete formwork is formed. This is repeated sequentially, and the pier is set up for each construction section above. The part where the concrete member thickness of the uppermost part of the pier is enlarged and the solid part 2c are formed by assembling the reinforcing bars and the formwork at the construction site of the pier and placing the concrete in the same manner as the lower end part. A bridge girder is built on the completed pier.

The construction method of the pier of the present invention is not limited to the embodiment described above, and can be implemented as other forms within the scope of the present invention.
For example, the anchor provided on the truss member 21 for connecting the precast outer mold 16 and the precast inner mold 17 is provided in accordance with the vertical pitch of the strip reinforcing bars 13 and 14 as shown in FIG. When forming the form unit, the rebars 13 and 14 can be arranged to be supported by these anchors 21e. Further, the tip portions of these anchors 21e can be bent upward. Thereby, arrangement | positioning of the band reinforcement 13 and 14 can be performed efficiently.

  Further, the precast outer mold frame 16 and the precast inner mold frame 17 which are opposed to each other without using the truss member 21 or together with the truss member 21 using the intermediate band reinforcing bar 15 can be connected while suppressing relative displacement. . For example, as shown in FIG. 11, a reinforcing bar having an axis in an oblique direction, that is, an oblique member 27, is fixed over a plurality of intermediate band reinforcing bars 15 in the intermediate band reinforcing bars 15 arranged in the vertical direction. When the slanted member 27, the strip reinforcing bar 15, and the two precast concrete plates 16 and 17 form a truss structure, and the formwork unit formed by these members is lifted, the displacement between the two precast concrete plates Can be kept small.

On the other hand, the horizontal reinforcing bars arranged at the corners are not limited to the U-shaped reinforcing bars 24 as in the above embodiment, and the reinforcing bars may be arranged horizontally as shown in FIG. 12 or FIG. it can.
In the example shown in FIG. 12, an L-shaped reinforcing bar 28 bent in an L shape and a hooked reinforcing bar 29 whose one end is bent in a hook shape are used. Further, the band reinforcing bar 13 of the precast outer mold 16 and the band reinforcing bar 14 of the precast inner mold 17 included in one mold unit U _A adjacent to each other at the corner 2a are the same as in the embodiment shown in FIG. A predetermined length is added in the horizontal direction. Hoop 13 of precast outer frame 18 having the other mold units U _B is previously protrude a predetermined length from the end face, hoop 14 precast inner die frame 19, extends to the vicinity of the side surface 2d adjacent piers The hook is bent at the tip.

The L-shaped reinforcing bar 28, along the extension of the hoop 13a projecting from precast outer frame 16 of one of the mold units U _A insert the tip toward the end face of the strip reinforcing bars 13a. Then, it is assumed that distal end hook portion provided in the other mold units U hoop 14b projecting from precast inner die frame 19 of _B is locked, the joint 25 to the band reinforcement 13a whose tip butted Connect by. On the other hand, processed rear portion 28a bent into an L-shape is connected to the hoop 13c projecting from the other mold units U _B precast outer frame 18. Further, hooked rebar 29, pledged along an extension line of the hoop 14a projecting from precast inner die frame 17 of one of the mold units U _A, with connecting tip belt-reinforcing bar 14a, the rear end portion locking the hook portion to the hoop 13c projecting from the other mold units U _B precast outer frame 18.

The example shown in FIG. 13 uses two hooked reinforcing bars 41 and 42 whose rear end portions are bent into a hook shape.
The hoop 14 of hoop 13 and precast inner die frame 17 of the precast outer frame 16 having the one of the mold units U _A, which are adjacent in the corners 2a, similarly to the embodiment shown in FIG. 8, the horizontal A predetermined length is given in the direction. However, the end face 16b of the precast outer frame 16 and the precast inner die frame 17 of the mold unit U _A in this example, has become a position where the position of 17b are aligned in the direction of placing the hoop 13,14. On the other hand, hoop 13b projecting from precast outer frame 18 and pre-cast in the mold 19 having the mold unit U _B has a successive ones are bent to the U-shaped as in the example shown in FIG. 8 .

It said hooked rebar 41, insert the tip along the extension line of the hoop 13a projecting from precast outer frame 16 of one of the mold units U _A towards the end surface of the band reinforcement 13a. Then, it protrudes from the other mold units U precast outer frame 18 and precast within mold 19 _B superimposed with part of the bending around the hoop 13b in a U shape, the belt reinforcing bar tip is abutted 13a is connected by a joint 25. Another hooked reinforcing bar 42 is inserted into the end of the band reinforcing bar 14a along the extension line of the band reinforcing bar 14a protruding from the precast inner mold 17, and is connected to the band reinforcing bar 14a. Processing portion bent in a hook shape which is provided at the rear end of these hooked rebar 41, superimposed with a portion of the U-shaped hoop 13b protruding from the other mold units U _B, corner It settles in the corner concrete.
In order to improve working efficiency, it is preferable to use a mechanical joint for connecting the L-shaped reinforcing bar 28 and hooked reinforcing bars 29, 41, and 42 to the band reinforcing bar.
Thus, even when horizontal reinforcing bars are arranged, the amount of work can be reduced and the number of joints of reinforcing bars can be reduced.

On the other hand, in addition to the method of arranging the horizontal reinforcing bars as shown in FIG. 9, for example, as shown in FIG. 14 or FIG. In this way, horizontal reinforcing bars can be arranged.
In the example shown in FIG. 14, similarly to the example shown in FIG. 9, a reinforcing bar 51 connected to the band reinforcing bar of the partition wall is protruded in a portion where the precast inner mold 17 of the A type mold unit U _A ′ is interrupted. However, in this example, the precast inner mold 17 of the A type mold unit U _A ′ is bent in the direction along the side face of the partition wall at the interrupted portion, and a predetermined length protrudes in the direction along the partition wall. The rebar 51 protrudes from the protruding end surface.
On the other hand, the mold units U _C C-type for forming the partition wall protrudes each band reinforcement 23 two precast mold 20, 20 disposed so as to face, it turned bent into a U-shape Are continuous. The tip end portion 23a of the band reinforcing bar protruding in the U shape is set at a position where it does not overlap the tip of the reinforcing bar 51 protruding from the _A type formwork unit U _A '. Further, as shown in FIG. 14, a hooked reinforcing bar 52 is connected to the reinforcing bar 51 protruding from the _A type formwork unit U _A ′ from the side by a joint 53. The rebar 52 with the hook is overlapped with the U-shaped band rebar and the portion bent into the hook shape is embedded in the concrete placed at the construction site of the bridge pier, whereby the tensile force of the band rebar 23 is obtained. Is transmitted and the displacement of the reinforcing bars in the vertical direction can be restricted.

In the example shown in FIG. 15, the mold unit U _A ″ used for the long side portion of the pier cross section is divided into two at the portion joined to the partition wall, and each of the divided mold units U _A ″ is predetermined. After being arranged at the position, the band rebars 13 and 14 embedded in the precast outer mold 16 and the precast inner mold 17 are connected by a joint 54. In addition, it is desirable to use the grout type joint which inserts the edge part of the reinforcing bar connected from the both ends of a tubular member and injects grout into a tubular member for this joint 54.

On the other hand, the mold unit U _C used for the partition wall portion projects the end of the band reinforcing bar 23 from the two precast molds 20 in the same manner as the example shown in FIG. Then, after the formwork unit U _A ″ and the formwork unit U _C are arranged, two from the outside of the outer peripheral surface of the pier along the extension lines of the band reinforcing bars 23b respectively protruding from the end faces of the two precast formwork 20 The hooked reinforcing bar 55 is inserted into the hooked reinforcing bar 55. The hooked reinforcing bar 55 has a hook-like bent at its rear end as shown in Fig. 15. The tip of the hooked reinforcing bar 55 is precast. The band reinforcing bar 23b protruding from the end face of the formwork 20 is connected by the joint 56, and the portion bent into a hook shape at the rear end is embedded and fixed in the concrete cast at the construction site of the pier.
With such a configuration, even if a horizontal reinforcing bar is arranged at a portion where the long side portion of the cross section of the pier that is substantially rectangular and the partition wall are joined, efficient work can be realized.

1: bridge girder, 2: pier, 2a: corner section of pier cross section, 3: abutment, 4: caisson, 5: footing,
11: Main reinforcing bar at a position along the outer peripheral surface, 12: Main reinforcing bar at a position along the inner peripheral surface, 13: A reinforcing bar at a position along the outer peripheral surface, 14: A reinforcing bar at a position along the inner peripheral surface, 15: Intermediate rebar, 16: Precast outer formwork, 17: Precast inner formwork, 18 Precast outer formwork, 19: Precast inner formwork, 20: Precast formwork of partition wall part, 21: Truss member, 22: A Reinforcing bars protruding from a type of formwork unit, 23: Band reinforcing bars arranged in the partition wall part, 24: U-shaped reinforcing bars, 25: Joints, 26: Connecting reinforcing bars, 27: Diagonal members, 28: L-shaped reinforcing bars, 29: Hooks Rebar,
31: Production stand, 32: Inner formwork, 33: Outer formwork,
41, 42: Rebar with hook,
51: Reinforcing bars connected to the reinforcing bars of the bulkhead 52: Reinforcing bars with hooks 53: Fittings 54: Fittings 55: Reinforcing hooks 56: Fittings
U _A : A type formwork unit, U _B : B type formwork unit, U _C : C type formwork unit

Claims (5)

A method of constructing a pier having a rectangular cross-sectional shape and having a space inside by using a formwork formed of precast concrete and integrating the concrete placed on site with the formwork,
A precast outer mold made of precast concrete having a predetermined height and arranged in the circumferential direction of the pier to form an outer peripheral surface of the pier, and the precast at a predetermined interval from the precast outer mold A precast inner mold made of precast concrete that is connected to the outer mold and forms a hollow inner peripheral surface of the bridge pier, and a plurality of embedded in the horizontal direction in each of the precast outer mold and the precast inner mold A formwork unit comprising: a steel bar reinforcing bar; and a steel bar reinforcing member embedded in the precast outer formwork and an intermediate belt reinforcing member that horizontally connects the steel bar reinforcing member embedded in the precast inner formwork. ,
On the foundation of the pier or the already formed part of the pier, the main reinforcing bar erected is inserted between the precast outer formwork and the precast inner formwork to place the formwork unit. A step of arranging a plurality of the formwork units in the circumferential direction excluding the corners of the piers;
A horizontal rebar is arranged at the corner, and a mold at the corner is assembled on-site, in the mold at the corner and between the precast outer mold and the precast inner mold. And placing concrete into
The step of arranging the mold units, the step of arranging the reinforcing bars at the corners, assembling the mold, and the step of placing the concrete are sequentially started upward. How to build a pier. One of the mold units arranged so as to be adjacent to both sides of the corner portion excluding the corner portion is formed from the substantially vertical end surfaces of the precast outer mold frame and the precast inner mold frame. Project the end of the band rebar horizontally toward each corner,
The other mold unit protrudes horizontally from the substantially vertical end faces of the precast outer mold frame and the precast inner mold frame toward the corner portion, and is a U-shaped continuous band at the corner portion. Have rebars,
As the horizontal reinforcing bars to be arranged at the corners after the mold unit is arranged, two reinforcing bars with hooks having a rear end bent into a hook shape are used. The rebar with the hook is inserted from the tip toward the end surface of the protruding band reinforcing bar along the extension line of the band reinforcing bar protruding from the end face, and the band reinforcing bar protruding from the hooked reinforcing bar and the one formwork unit Connect the end,
The method of building a pier according to claim 1, wherein a portion of the hooked reinforcing bar bent into a hook shape is embedded and fixed in the corner portion. One of the mold units arranged so as to be adjacent to both sides of the corner portion excluding the corner portion is formed from the substantially vertical end surfaces of the precast outer mold frame and the precast inner mold frame. Project the end of the band rebar horizontally toward each corner,
The other mold unit protrudes horizontally from the substantially vertical end faces of the precast outer mold frame and the precast inner mold frame toward the corner portion, and is a U-shaped continuous band at the corner portion. Have rebars,
A U-shaped reinforcing bar bent in a U-shape is used as a horizontal reinforcing bar arranged in the corner portion after the formwork unit is arranged, and substantially parallel to both sides of the bent portion of the U-shaped reinforcing bar. The inserted portion is inserted along the extension line of the band reinforcing bar protruding from the end surface of the one formwork unit toward the end surface of the protruding band reinforcing bar, and protrudes from the U-shaped reinforcing bar and the one formwork unit. Connected to the end of the rebar
The main reinforcing bar disposed at the corner portion by a portion bent so as to form a U-shape of the band reinforcing bar protruding from the other formwork unit and a bent portion of the U-shaped reinforcing bar The method for constructing a pier according to claim 1, wherein: The precast outer formwork and the precast inner formwork are connected at predetermined intervals by a steel truss member,
The truss member is in close contact with the precast outer formwork and the precast inner formwork, and has two chords having an axis in the vertical direction, an oblique member connecting them in an oblique direction, and the two chord members Having a plurality of anchors fixed to each and embedded in the concrete of the precast outer formwork or the precast inner formwork,
The anchor is provided in accordance with the vertical interval of the rebars arranged in the horizontal direction at a predetermined interval in the vertical direction,
The method for constructing a pier according to any one of claims 1 to 3, wherein at the time of manufacturing the formwork unit, the band reinforcing bar is arranged to be supported by the anchor. The intermediate rebars are provided at predetermined intervals in the horizontal direction, and arranged in the vertical direction with respect to the respective rebars, and both ends are embedded in the precast outer mold frame and the precast inner mold frame,
Abutting an oblique member having an axis line in an oblique direction on the side surface of the band reinforcing bar arranged in the vertical direction, coupled to a plurality of the intermediate band reinforcing bar,
The method for constructing a pier according to any one of claims 1 to 4, wherein a relative displacement between the precast outer mold and the precast inner mold is constrained by the oblique member.

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