JP2008274586A - Pillar head construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pillar head construction method which is applicable to an overhanging erection method of a PC bridge by a moving work vehicle, wherein the method dispenses with large scale bracket timbering, and framework entire timbering, eliminates overflow of concrete at a floor slab portion of a laterally overhanging portion of a pillar head, and contributes to safe construction of the pillar head of few defects in a short construction period and at a low cost. <P>SOLUTION: According to the pillar head construction method, the pillar head 2 at the top of a bridge pier 1 is divided into a horizontal girder section 2a and a horizontal girder section 2b, and the horizontal girder section 2a is constructed of cast-in-place concrete A by extending scaffolding which has been used in construction of the bridge pier 1, while the overhanging sections 2b are each produced by a precast concrete block B. Then each precast overhanging section B is hoisted by a hoisting device and drawn to the horizontal girder section, and reinforcements, PC sheath pipes, etc. are connected to each other in an infill section C, followed by placing concrete, to thereby connect the precast overhanging sections B to the horizontal girder section A in the infill section C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a column head construction method applied to a PC (prestressed concrete) bridge overhang construction method.

  As a construction method of a PC bridge, an overhang construction method using a mobile work vehicle is generally known. As shown in FIG. 4, this type of construction method is such that a pillar head 2 is built on a pier 1 and left and right mobile work vehicles W are installed thereon, and the mobile work vehicles W are sequentially sent forward. The main girder 3 is installed. A projecting part 2b projecting from the cross beam part 2a of the column head 2 to the left and right in the bridge axis direction constitutes a part of the main girder, and the mobile work vehicle projects from the existing part 2b of the main girder to the adjacent section. W is installed, and at the front end of this mobile work vehicle W, the assembly of the formwork, the assembly of the reinforcing bars, the placement of the PC steel material, and the concrete placement and curing are performed one block at a time.

  In this construction method, first, construction is started from the column head 2. Conventionally, the column head 2 is constructed without assembling a mobile work vehicle, as shown in FIG. 5, assembling bracket supports 50 on both sides near the top of the pier 1, and placing a frame on the bracket support 50. The total support work 51 was assembled and carried out, and the cross beam portion 2a and the left and right overhang portions 2b of the column head 2 were constructed by concrete cast on site.

Also, in the construction of the column head, in the construction of the column head 2, the installation range of the formwork is assembled on the bottom surface and the side surface, and the top surface of the bottom slab portion 2 b ₁ is not installed because the concrete surface needs to be smoothed. The method is usually taken. In addition, since the formwork of the column head 2 is not repetitive work unlike the overhanging construction method using a mobile work vehicle, the formwork is often used once, and the formwork material is also a wooden formwork. It is normal.

  In addition, there exist patent documents 1-4 as a prior art document relevant to construction of the column head of this invention. The invention of Patent Document 1 is a column head construction method in the overhanging construction method of a corrugated steel web bridge. The construction of the head of the column is simplified by installing the concrete of the cross beam part and the lower floor slab concrete of the overhanging part for each left and right block.

  The invention of Patent Document 2 is a column head construction method and an erection work vehicle, in which a small area column head (horizontal girder part) is constructed on a bridge pier, and left and right overhanging construction vehicles are inserted on this. This work vehicle is used to project the left and right bridge bodies (projected parts) of the column head, reduce the size of the column head, and eliminate the need for a bracket provided on the side of the pier.

  The invention of Patent Document 3 is a construction method of a precast column head and a pier column head, and the precast column head (the cross beam portion and the left and right overhang portions) is composed of a lower floor plate, an upper floor plate, and a web, and its lower opening The pier seed reinforcing bar protruding from the head of the pier is penetrated into the part, and concrete is cast to integrate the pier and the precast column head, thereby shortening the construction period.

  The invention of Patent Document 4 is a method for constructing a column head of a PC cable stayed bridge, and a mobile work vehicle is temporarily supported on a bridge pier top by a support bracket on the pier top and a diagonal of a main tower. The column head is constructed using a mobile work vehicle as a work scaffold, and the support material and the construction period are shortened.

JP 2005-171521 A JP 2004-218316 A JP 2003-328320 A Japanese Patent No. 2550846

  The conventional method of bracket construction and frame total support construction in which the cross beam part and the overhanging part of the column head are integrally constructed with on-site casting concrete has the following problems.

  (1) Bracket support work needs to be assembled on a fairly wide scale, and requires a large amount of support work material, which increases the cost of support work materials, and requires a lot of labor to assemble and disassemble the work period. There were problems such as unavoidable lengthening of the period.

  (2) Because the rebar of the pillar head is usually arranged with high density of reinforcing bars, we want to place ready-mixed concrete with high fluidity as much as possible in order to improve the filling of concrete. Since the bottom plate portion in the left and right overhang portions of the portion does not have a formwork on the upper surface, in the case of ready-mixed concrete with high fluidity, the concrete overflows in the bottom plate portion and cannot be stopped. In order to solve this problem, construction was carried out while delicately controlling the fluidity of ready-mixed concrete, but the construction method was prone to defects such as insufficient filling due to insufficient fluidity of the concrete in the cross beam part.

  (3) As for the formwork material, there are many examples of single use with wooden formwork, and there are problems such as inferior economy.

  The present invention has been made to solve the above-described problems of the prior art, and in the construction of a column head that is applied to an overhanging construction method using a mobile work vehicle of a PC bridge, a large-scale bracket support work and a total frame support work are provided. It is possible to eliminate the need for work, and it is possible to eliminate the overflow of concrete in the floor slabs of the left and right overhangs of the column heads, and to make it possible to safely build a column head with few defects at a low cost in a short period of time. It is to provide a construction method of the part.

  Claim 1 of the present invention is a column head of a pier on which a mobile work vehicle used in a bridge overhang construction method is installed, and a cross beam portion provided on the top of the pier, and a bridge axis direction from the cross beam portion In the construction method of the column head composed of the overhanging part that protrudes to the wall, the cross beam part is built with on-site cast concrete, the overhanging part is made of precast concrete block, and the precast overhanging part is joined to the cross beam part It is the construction method of the column head characterized by doing (refer FIGS. 1-3).

  The present invention is applied to a PC bridge, such as a PC girder bridge or a PC cable-stayed bridge, which performs a cantilever extension construction method using a mobile work vehicle (see FIG. 4). The present invention can also be applied to a bridge having a flat oblique angle (when the bridge pier is shifted by about 10 ° to 30 ° with respect to the direction perpendicular to the bridge axis). The bridge pier and the column head are rigidly connected, and a support may be installed between them.

  The construction method of the column head according to the present invention is basically based on the construction of the column head by dividing the cross beam portion directly above the bridge pier and the overhanging portion adjacent thereto, and the cross beam portion is first constructed with on-site cast concrete. The overhanging portion is manufactured in advance as a precast concrete block, and the column head portion on which the left and right movable work vehicles can be installed is formed by the cross beam portion and the precast overhanging portion of the on-site cast concrete.

  The horizontal girder part to be built first extends the scaffold that was installed when the pier was constructed, and the floor slab part (floor slab overhanging part) is built simply by installing a bracket support. can do. (1) Since the construction area is secured and the scaffolding is only added when the cross girder is constructed, there is no need to modify the scaffolding when constructing a conventional bracket support, shortening the process and reducing costs. Is possible. (2) Overflowing concrete into the bottom plate part of the overhanging part that constitutes the first part of the main girder as in the past by building the cross girder part directly above the pier in the field first in the field. Therefore, ready-mixed concrete with high fluidity suitable for reinforcing bars arranged at high density can be applied, so that the filling property of the concrete is improved and construction with few defects is possible.

  The precast overhanging portion is larger than the main girder segment in the precast segment construction method, and since it is a single-piece production, it is preferable that the precast overhanging portion be manufactured near the suspension beam under the pier. Even in rivers and steep slopes, the assembly space for mobile work vehicles is secured and leveled directly under the pier, so it is possible to produce precast overhangs using that space. Moreover, it is not limited to just under the bridge pier, but can be manufactured in another space or a special production yard and carried to the pier directly under the rail.

  (1) Since this precast overhang can be lifted in a precast block, the conventional bracket support work and the total frame support work on the bracket support work can be omitted, which shortens the process and reduces the cost. It becomes possible. (2) Since the precast overhanging part can be manufactured in advance at the site that is directly under the lifting position or movable to the lifting position, casting and curing of formwork, rebar, PC steel, and concrete This process can be shortened. (3) The formwork and support for the overhang construction method installed in the mobile work vehicle can be diverted to the formwork and support used for the production of the precast overhang, which can reduce costs. Become. (4) The construction of the precast overhang will be on the ground, improving work safety and reducing crane work at high altitudes. improves.

  Claim 2 of the present invention is a column head construction method according to claim 1, wherein the cross beam portion and the precast overhanging portion are joined together via a clogging portion. Yes (see FIG. 1).

  It is also possible to join the cross beam part and the precast overhanging part with a structural adhesive as in the precast segment method, but since the reinforcing bars are arranged at a high density on the column head, It is preferable to connect a reinforcing bar, a PC steel sheath tube, or the like at this gap portion, and to place and join concrete. In terms of design, it does not fall under the precast segment construction method, and can be applied only by considering the increase in the amount of reinforcing bars for the reinforcing bar joints. The formwork and safety equipment used for the filling portion can be attached in advance to the precast overhanging portion.

  Claim 3 of the present invention is a method for constructing a head of a pillar according to claim 1 or claim 2, wherein a scaffold used for construction of a bridge pier is extended upward to build a cross beam portion. It is a construction method of the part (see FIG. 2).

  Since the scaffold used for the construction of the bridge pier is used for the construction of the cross beam part, the construction area is secured and only the scaffolding is added, so the modification of the scaffolding when constructing the conventional bracket support work Is no longer necessary.

  According to a fourth aspect of the present invention, in the method for constructing a pillar head according to any one of the first to third aspects, an erection beam projecting in the direction of the bridge axis is installed on the cross beam portion. The column head construction method is characterized in that the precast overhanging portion is lifted to the height position of the cross beam portion by the lifting device provided on the erection beam and horizontally moved to the joining position to the cross beam portion (see FIG. 3). ).

  This is an example of a method of lifting the precast overhanging part. After installing the lifting device, refilling device, and lateral movement device on the construction beam fixed to the cross beam with an anchor, lifting the precast overhanging part and changing the size , Pull it into place. The precast overhanging part can be lifted outside the previously constructed pier scaffolding and joined to the cross beam part, so there is no need to disassemble the scaffolding for lifting, and the process can be shortened and the cost can be reduced. .

  In the case of a structure in which a support is installed between the bridge pier and the column head, temporary support concrete and a temporary anchor are installed. In this case, the anchor of the beam installed in the upper part of the cross beam is It can be substituted by connecting to a temporary anchor.

  In addition, as described above, in the production of the precast overhang portion, a part of the formwork member of the mobile work vehicle can be used for the formwork. In this case, the moving work is performed when the precast overhang portion is lifted. The formwork and support for the overhang construction method installed in the car can be lifted simultaneously with the precast overhang. Thereby, the assembly process of the mobile work vehicle used as the post construction of the head of the present invention can be shortened.

  Since the present invention is configured as described above, the following effects can be obtained.

(1) Since the column girder part of the column head is constructed in advance by on-site placement and the precast block-like overhanging part is joined, the conventional large-scale bracket support work and total framework Support work can be eliminated, and the construction period can be greatly shortened, the cost can be reduced, and the safety can be improved.

(2) By constructing the cross-beam part of the column heads on-site, use ready-mixed concrete with appropriate fluidity without considering the overflow of concrete to the bottom plate part of the overhanging part Therefore, it is possible to improve the filling property of the concrete, and to perform the construction with few defects, and it is possible to construct the column head with few defects safely at a low cost in a short time in combination with the precast block of the overhang portion.

  Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a side view showing an example of a column head constructed by the construction method of the present invention. FIG. 2: is a side view which shows an example of the construction method of the cross beam part of the column head which is the 1st process of the construction method of the column head of this invention. FIG. 3: is the side view which shows an example of the construction method of the overhang | projection part of the column head which is a 2nd process, and the front view seen from the bridge-axis direction.

  In the embodiment of FIG. 1, a column head 2 is built on a pier 1 of a PC box girder bridge. This column head 2 is composed of a cross beam portion 2a directly above the pier and an overhanging portion 2b projecting to the left and right sides of the cross beam portion 2a in the bridge axis direction. Space for arranging the mobile work vehicle W used in the overhanging construction method on the left and right is secured (see FIG. 4). The pier 1 and the column head 2 may be rigidly connected, or a support may be installed between the pier 1 and the column head 2.

  As shown in FIG. 4, the cross beam portion 2b constitutes the first portion of the main beam 3. At the front end portion of the mobile work vehicle W protruding from the cross beam portion 2b, the assembly of the formwork, the assembly of the reinforcing bars, the PC The main girder 3 (on the left side of FIG. 4B) is built by arranging the steel materials, placing concrete and curing, and repeating the above steps while moving the mobile work vehicle W.

  In the present invention, as shown in FIG. 1, the column head portion 2 is divided into a cross beam portion 2a and a cross beam portion 2b, the cross beam portion 2a is constructed with a cast-in-place concrete A, and the overhang portion 2b is precast concrete. The block B is manufactured, and the precast projecting portion B is joined to the cross beam portion A by the clogging portion C.

(1) Construction of cross girder part A As shown in FIG. 2, following construction of the pier 1, the construction scaffold 10 around the pier is extended as it is, and the cross girder part A is constructed on site. Here, since only the cross beam portion 2a is constructed, the bottom plate portion related to the main girder of the overhang portion 2b is not constructed as in the prior art. The overflow does not occur. Therefore, fluid ready-mixed concrete suitable for the cross-girder structure is selected and constructed.

  The upper slab portion of the cross beam portion 2a is provided with a floor slab overhanging portion that projects in a direction perpendicular to the bridge axis, as in the cross section of the main girder 3. After the installation is completed, a small bracket is attached to the side surface of the cross-girder concrete, and the concrete on the upper part is cast to build the floor slab overhanging portion of the cross-girder portion 2a.

(2) Construction of precast overhanging portion B As shown in FIG. 3, a steel or concrete cradle 20 is installed on the cross beam portion A, and this cradle 20 is parallel to the bridge axis direction. An erection beam (H-shaped steel etc.) 21 is arranged. The erection beam 21 protrudes to the right and left in the bridge axis direction with a predetermined length, and the central portion thereof is connected and fixed to an anchor embedded in the cross beam portion A or a temporarily fixed anchor 22.

  A horizontal beam 23 parallel to the direction perpendicular to the bridge axis is installed on the tip of the erected beam 21, and a lifting device (center hole jack or the like) 24 is installed on the horizontal beam 23. The precast overhanging portion B is lifted at a position where it does not interfere with the scaffold 10 of the pier 1 by the lifting material of the lifting device 24, and is lifted to a predetermined height position where joining can be performed.

  The precast overhanging portion B that has been lifted is replaced with a suspended material of a separate refilling device 25. Fine adjustment of the height after replacement is performed with a general-purpose jack. Thereafter, the lateral movement device (hydraulic jack or the like) 26 is horizontally moved in the direction approaching the transverse beam portion 2a, pulled to a predetermined position, and the transverse beam portion A and the precast overhanging portion B are temporarily fixed with a general-purpose steel material. . Between the cross beam portion A and the precast overhanging portion B, a clogging portion C of about 0.5 to 1.0 m is formed. Therefore, the horizontal movement is performed until the clogging portion C remains.

  The formwork and safety equipment to be used for the filling portion C are attached to the precast overhanging portion B in advance, and after connecting the reinforcing bars and the PC steel sheath tube in the filling portion C, the concrete is cast in between. Build the plug C.

  For lifting the precast overhang portion 2b, a lifting jig 27 connected to a lifting material and a formwork / supporting structure 30 suspended from the lifting jig 27 can be used. Using this formwork / supporting structure 30, the precast overhang portion 2 b is manufactured in the vicinity immediately below the suspension beam under the pier or in other places. The formwork / supporting work 30 can also be a formwork / supporting work for the overhang construction method installed in the mobile work vehicle W.

  In addition, although the above was illustrated about PC box girder bridge, it cannot be overemphasized that it is applicable not only to this but another PC bridge.

It is a front view which shows an example of the column head built by the construction method of this invention. It is a side view which shows an example of the construction method of the cross beam part of the column head which is the 1st process of the construction method of the column head of this invention. An example of the construction method of the overhang | projection part of the pillar head which is the 2nd process of the construction method of the pillar head of this invention is shown, (a) is a side view, (b) is the front view seen from the bridge axis direction. The overhanging construction method using the moving work vehicle of PC bridge is shown, (a) is a side view, (b) is a front view seen from the bridge axis direction. It is a side view which shows the construction method of the conventional pillar head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pier 2 ... Column head 2a ... Cross girder part 2b ... Overhang part 3 ... Main girder 10 ... Construction scaffold 20 ... Stand 21 ... Construction beam 22 ... Anchor or temporarily fixed anchor 23 ... Side beam 24 ... Lifting Equipment 25 ... Replacement equipment 26 ... Horizontal movement equipment 27 ... Raising jig 30 ... Formwork / support work A ... Transverse girder (on-site concrete)
B: Precast overhang (precast concrete block)
C ... Stuffed part W ... Mobile work vehicle

Claims (4)

It is a column head of the pier where the mobile work vehicle used for the bridge overhang construction method is installed, and is composed of a horizontal girder part provided at the upper part of the pier and an overhang part projecting from the horizontal girder part in the bridge axis direction In the column head construction method,
A method for constructing a column head characterized in that a cross beam portion is constructed with cast-in-place concrete, an overhang portion is manufactured with a precast concrete block, and a precast overhang portion is joined to the cross beam portion.   The column head construction method according to claim 1, wherein the cross beam portion and the precast overhang portion are joined via a clogging portion.   The construction method of a pillar head according to claim 1 or 2, wherein the scaffold used for construction of the bridge pier is extended upward to build a cross beam portion. The construction method of the column head according to any one of claims 1 to 3, wherein an installation beam extending in a bridge axis direction is installed on the cross beam portion, and a lifting device provided on the installation beam is used. A column head construction method characterized in that the precast overhanging part is lifted to the height position of the cross beam part and horizontally moved to the joining position to the cross beam part.

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