Reinforcement method for reinforced concrete column

Abstract

To provide a reinforcement method for a reinforced concrete column that can reinforce an existing reinforced concrete column efficiently by regulating the material used even when the concrete column has a considerable height.SOLUTION: A reinforcement method for a reinforced concrete column comprises: a mold-sliding process of forming a reinforcement concrete layer 51 of a bottom work section, and then shifting each split-body mold 13 of a demolded cylindrical-body mold 12 upon the demolding by sliding with the standing posture in a direction away from the formed bottom reinforcement concrete layer 51; a mold face preparation process of preparing the inner mold face of each split-body mold 13 by workers who enter a work space 56 created by the mold-sliding between itself and the bottom reinforcement concrete layer 51; and a lift-and-transfer process of then lifting up the split-body mold 13 with its inner face prepared and re-positioned it as a member of the cylindrical-body mold 12 for forming the reinforcement concrete and re-positioning e layer 51 of the next-stage work section.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a reinforcement method for reinforced concrete columns, and in particular to a reinforcement method for reinforced concrete columns using a cylindrical main formwork formed by joining together multiple divided main formworks circumferentially in order to build a reinforcing reinforced concrete layer around an existing reinforced concrete column. [Background technology]

[0002] In construction work to seismically reinforce existing reinforced concrete bridge piers that were constructed more than several decades ago, or other old existing reinforced concrete pillars, common methods include the RC wrapping method, in which reinforcing bars are assembled around the existing reinforced concrete pillars such as bridge piers, formwork is installed, and additional reinforcing concrete is poured, and the steel plate wrapping method, in which reinforcing steel plates are wrapped around existing reinforced concrete pillars such as bridge piers, and a hardening material such as non-shrink mortar or epoxy resin is filled between the wrapped reinforcing steel plates and the concrete frame to integrate them.

[0003] In the RC lining method, when installing formwork around an existing reinforced concrete column, the outer concrete surface is treated with, for example, a water jet to create an uneven surface. Then, anchors are driven into the treated uneven surface, and separators are attached to the anchors. The separators then position the installed formwork while maintaining a predetermined gap between it and the concrete surface. This requires driving multiple anchors into the concrete surface to ensure the installed formwork has sufficient strength to withstand the internal pressure applied to the formwork when the reinforcing concrete is poured, which requires a lot of work. Furthermore, adjusting the lengths of the separators connected to the multiple anchors to maintain the predetermined gap between the concrete surface and the formwork also requires a lot of work.

[0004] On the other hand, for example, Patent Document 1 below discloses a formwork device for a rectangular columnar concrete structure that can support from the outside the load due to internal pressure applied to the formwork during concrete pouring when constructing a new rectangular columnar concrete structure without using many separators. The formwork device described in Patent Document 1 includes a rectangular cylindrical formwork formed by assembling a pair of split formworks having inner peripheral surfaces corresponding to approximately half of the outer peripheral surface of the rectangular columnar concrete structure to be constructed, a plurality of wooden supports attached to the outer peripheral part of the rectangular cylindrical formwork so as to extend in the vertical direction, and a plurality of stages of retaining members attached continuously in a rectangular ring shape in the circumferential direction around the outer peripheral parts of the plurality of wooden supports, and the retaining members are formed by beam members on four sides that are connected and fixed integrally at four intersecting corners by corner fixing guides or retrofitting guides. This also means that the load caused by the internal pressure exerted on the rectangular cylindrical formwork when concrete is poured can be supported from the outside by retaining members attached continuously in a rectangular ring shape around the periphery, via multiple wooden support members attached and extending in the vertical direction to the outer periphery of the formwork. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-181439 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the formwork device described in Patent Document 1, the formwork device is laid out in a work area on the ground away from the construction location of the rectangular columnar concrete structure, and work is carried out to assemble a pair of split formworks into a rectangular cylindrical shape, and to attach multiple wooden supports and multiple stages of retaining members arranged in a rectangular ring shape, to form the formwork device.The formwork device is then raised upright using a crane or the like, and then lifted and installed at the construction location for use.Therefore, when, for example, a reinforcing layer of reinforced concrete is poured around an existing reinforced concrete column, structures above the existing reinforced concrete column, such as a bridge abutments, get in the way, making it difficult to lift the formwork device and install it in the designated location.

[0007] Furthermore, when reinforcing an existing reinforced concrete column by pouring an additional layer of reinforced concrete, the cost of construction is higher than when building a new reinforced concrete column, as it requires a lot of work, such as processing and assembling formwork on-site to fit the existing reinforced concrete column and adjusting separators to ensure the correct shape. For this reason, there is a need to develop a technology that can reinforce concrete columns more efficiently.

[0008] To provide a reinforcement method for a reinforced concrete column that can reduce the labor required for processing and assembling formwork on-site when reinforcing an existing reinforced concrete column by pouring an additional reinforced concrete layer, and can reinforce the concrete column more rationally, thereby effectively suppressing costs during construction. [Means for solving the problem]

[0009] The present invention is a reinforcement method for reinforced concrete columns using a cylindrical main body formwork formed into a cylindrical shape of a predetermined height by joining together a plurality of divided main body formworks in the circumferential direction, for constructing an additional reinforced concrete layer around an existing reinforced concrete column. The divided main body formwork constituting the cylindrical main body formwork is formed by arranging a plurality of formwork units connected together as a unit via support beams and assembling them at a predetermined height, and is used by rotating it multiple times from the bottom to the top of the existing reinforced concrete column. The cylindrical main body formwork is installed around the lower end portion of the existing reinforced concrete column, and concrete is poured into the cylindrical pouring space of concrete held between the cylindrical main body formwork and the existing reinforced concrete column. The above object has been achieved by providing a reinforcement method for reinforced concrete columns in which the following steps are carried out: a form sliding process in which, after forming a reinforcing concrete layer for the lowest tier of construction rods by sliding each of the divided main body formworks of the demolded tubular main body formwork in an upright position away from the formed lowest tier of reinforcing concrete layer; a form surface cleaning process in which a worker enters the work space created between the demolded tubular main body formwork and the reinforcing concrete layer of the lowest tier and cleans the inner form surface of each of the divided main body formworks; and a lifting and repurposing process in which the divided main body formworks whose inner form surface has been cleaned are lifted upward and re-installed as constituent members of the tubular main body formwork for forming the reinforcing concrete layer for the next tier of construction rods.

[0010] The reinforcement method for a reinforced concrete column of the present invention uses the divided main body formwork converted into the next-stage construction rod in the lifting and conversion step to pour concrete into the cylindrical concrete pouring space held between the tubular main body formwork installed around the existing reinforced concrete column and the existing reinforced concrete column, thereby forming a reinforcing concrete layer for the next-stage construction rod, and then hangs down the divided main body formwork of each of the removed tubular main body formworks in an upright state to the part of the lowest-stage construction rod, and forms It is preferable that the following steps be carried out: a formwork suspending and moving process in which the formwork is moved away from the lowest reinforced concrete layer that has been installed; a formwork surface re-scraping process in which workers enter the work space created between the formwork and the lowest reinforced concrete layer and scrape the inner formwork surfaces of each of the divided main body formworks; and a re-hoisting and repurposing process in which the divided main body formworks whose inner formwork surfaces have been scraped are lifted upward and reinstalled as constituent members of the tubular main body formwork to form the reinforcing concrete layer of the next layer of construction rods.

[0011] Furthermore, in the reinforcement method for reinforced concrete columns of the present invention, temporary scaffolding used when assembling the reinforcing bars and the tubular main body formwork is installed around the existing reinforced concrete column while maintaining space for the tubular main body formwork to be arranged, and it is preferable that prior to the formwork sliding process or the formwork hanging and moving process, a scaffolding portion removal process is carried out in which part of the temporary scaffolding in the part of the lowest construction rod is removed so that the movement of the divided main body formwork is not hindered.

[0012] Furthermore, in the reinforcement method for reinforced concrete columns of the present invention, it is preferable that the existing reinforced concrete column has a rectangular cross-sectional shape, and that the cylindrical main body formwork made up of multiple divided main body formworks is assembled into a cylindrical shape with a rectangular hollow cross-section.

[0013] Furthermore, in the reinforcement method for reinforced concrete columns of the present invention, it is preferable that the load imposed by the internal pressure of the concrete poured inside is supported from the outside by an annular support beam formed by continuously integrating the support beams of multiple divided main body formworks, which are attached in multiple stages and extend in a ring shape circumferentially along the outer periphery of the cylindrical main body formwork. [Effects of the Invention]

[0014] According to the reinforcement method for reinforced concrete columns of the present invention, when reinforcing an existing reinforced concrete column by pouring an additional reinforced concrete layer, the labor required for processing and assembling formwork on site can be reduced, and the concrete column can be reinforced more rationally, effectively reducing construction costs. [Brief explanation of the drawings]

[0015] [Figure 1] 3 is a side view taken along the line BB in FIG. 2, illustrating a reinforcement method for a reinforced concrete column carried out using a formwork structure for a reinforced concrete column. [Figure 2] 2 is a top view taken along the line AA in FIG. 1, illustrating a reinforcement method for a reinforced concrete column carried out using a formwork structure for a reinforced concrete column. [Figure 3] 2 is a cross-sectional view taken along CC in FIG. 1, illustrating the formwork structure for a reinforced concrete column. [Figure 4] FIG. 4 is a side view of FIG. 3 as viewed from the right side, illustrating the formwork structure for a reinforced concrete column. [Figure 5] FIG. 10 is a perspective view illustrating a form unit made of steel form panels, viewed from the rear side. [Figure 6] FIG. 2 is a perspective view illustrating a split formwork structure. [Figure 7] FIG. 2 is a perspective view illustrating a divided support beam. [Figure 8] 4(a) is an enlarged view of part D in FIG. 3 explaining the joint structure of the support beam, (b) is an enlarged view of part E in (a), and (c) is a cross-sectional view taken along FF in (a). [Figure 9] Explaining the corner joint piece, (a) is a top view, (b) is an outer side view of (a) seen from the right side, and (c) is an inner side view of (a) seen from below. [Figure 10] FIG. 2(a) is a front view illustrating an outer fastening plate, and FIG. 2(b) is a front view illustrating an inner fastening plate. [Figure 11] 1(a) to 1(c) are process diagrams illustrating a reinforcement method for a reinforced concrete column according to a preferred embodiment of the present invention. [Figure 12] 1(a) and 1(b) are process diagrams illustrating a reinforcement method for a reinforced concrete column according to a preferred embodiment of the present invention. [Figure 13] (a) is an enlarged view of part G in Figure 12(a) illustrating the state in which the divided main body formwork is lifted and its lower end is supported by a height-adjustable support metal fitting, and (b) is an enlarged view of part H in (a). [Figure 14] (a) is a front view of the height-adjustable support bracket, and (b) is a side view. [Figure 15] FIG. 10 is an explanatory diagram of a form sliding process. [Figure 16] FIG. 10 is an explanatory diagram of the lifting and conversion process. DETAILED DESCRIPTION OF THE INVENTION

[0016] A reinforcement method for a reinforced concrete column according to a preferred embodiment of the present invention (see Figures 11(a) to (c) and Figures 12(a) and (b)) is preferably carried out via a reinforced concrete column formwork structure 10, which is installed so as to surround the pier 50 when constructing a reinforcing reinforced concrete layer 51 (see Figures 11 and 12) around an existing reinforced concrete column, for example, a reinforced concrete pier 50 having a rectangular cross section, as shown in Figures 1 and 2, to form a rectangular ring-shaped cylindrical concrete pouring space 52 (see Figure 3) between the pier 50 and the outer peripheral surface of the pier 50. In this embodiment, the formwork structure 10 for reinforced concrete columns is constructed by a simple construction method in which a plurality of split formwork structures 16, preferably assembled on the ground in a flat rectangular shape, are lifted up and installed around the pier 50, and the split main formwork 13 is connected and integrated into a cylindrical shape.This method allows a cylindrical concrete pouring space 52 to be formed efficiently and easily around the existing pier 50, and also allows the load due to the internal pressure applied to the formwork (cylindrical main formwork) 12 when pouring concrete to be firmly supported in a stable manner from the outside without using many separators 53 (see Figure 3).

[0017] In this embodiment, the formwork structure 10 for a reinforced concrete column is a formwork structure installed when a reinforcing reinforced concrete layer 51 is poured around an existing reinforced concrete pier 50, for example, having a rectangular cross section, as a reinforced concrete column. As shown in Figures 3 to 5, the formwork structure includes a cylindrical main body formwork 12 assembled into a cylindrical shape of a predetermined height by connecting and arranging a plurality of formwork units 11 (see Figure 5), and annular support beams 14 attached in multiple stages around the outer periphery of the cylindrical main body formwork 12. The cylindrical main body formwork 12 is formed into a cylindrical shape by connecting and integrating a plurality of divided main body formworks 13 that can be separated in the circumferential direction, and the annular support beam 14 is formed into a continuous annular shape by connecting and integrating a plurality of divided support beams 15 that can be separated in the circumferential direction. Each divided main body form 13 and divided support beam 15 are assembled on the ground to form a divided form structure 16 with the divided main body form 13 made of form units 11 abutting and joined to the divided support beam 15 (see Figure 6), and these divided form structures 16 are individually erected at the concrete pouring location and connected together to form a cylindrical concrete pouring space 52 by the cylindrical main body form 12 between it and the existing pier 50. When concrete is poured, the load due to internal pressure applied to the cylindrical main body form 12 can be stably and firmly supported from the outside by the multiple stages of annular support beams 14 abutting the outer periphery of the cylindrical main body form 12 and continuing in an annular shape.

[0018] In addition, in this embodiment, the pier 50, which is an existing reinforced concrete column, does not have, for example, a rectangular cross-sectional shape, and the cylindrical main body formwork 12 is assembled into a cylindrical shape with a rectangular hollow cross-section, and the annular support beam 14 is attached continuously in a rectangular ring shape in the circumferential direction.

[0019] In this embodiment, the form units 11 constituting the cylindrical main body form 12 and the divided main body form 13 are preferably steel form panels known as metal forms. As shown in Fig. 5, the steel form panel 11 is a known steel form member having a height of, for example, about 55 mm, and is composed of a vertically (horizontally) long rectangular face plate 11a, approximately 600 to 1,800 mm in length and 200 to 300 mm in width, and ribs 11b, such as vertical ribs, horizontal ribs, central vertical ribs, and central horizontal ribs, which are integrally joined in an upright state to the back side of the face plate 11a. The steel form panel 11 has a height of, for example, about 55 mm, and is formed with a plurality of fastening holes 11c, such as tie rod holes, U-clip holes, and nail holes, at appropriate locations on the ribs 11b, such as the vertical ribs, horizontal ribs, central vertical ribs, and central horizontal ribs. By engaging locking hardware 11d (see FIG. 6), such as U-clips or hook bolts, with these locking holes 11c, multiple steel form panels 11 are connected lengthwise and widthwise, preferably to form a rectangular flat plate of a predetermined size, thereby forming a divided main body form 13 having a predetermined height. Four divided main body form panels 13 are formed, and as will be described later, at a construction site where a reinforcing reinforced concrete layer 51 is poured around a reinforced concrete pier 50, these divided main body form panels 13 are connected and integrated to form a cylindrical main body form 12 (see FIG. 3), preferably having a rectangular hollow cross section and a predetermined height. For example, Metal Form manufactured by Okaya Construction Materials Co., Ltd. can be preferably used as the steel form panel that forms the form unit 11.

[0020] The annular support beam 14, which is attached in multiple stages in a rectangular ring shape around the outer periphery of the cylindrical main formwork 12 made of multiple steel formwork panels 11, is preferably composed of four segmented support beams 15. These segmented support beams 15 can be formed using various steel materials such as H-shaped steel and I-shaped steel. In this embodiment, the segmented support beams 15 can be formed using a support beam specifically designed for formwork, as shown in Figures 6 and 7. More specifically, they can be formed using a "wide panel beam" manufactured by Okaya Construction Materials Co., Ltd. The large-scale formwork support beam 15, which is a wide panel beam, is preferably formed by connecting a pair of channel steels 15a, each having a plurality of rectangular through-holes 15b formed at predetermined intervals along its length, back to back with gaps 15c through which bolts can be inserted, via end connecting plates 15d.

[0021] As will be described later, when the divided support beams 15 are installed in multiple stages (see Figure 4), through-holes 15b of the channel steel 15a of the large-form support beams that form the divided support beams 15 are inserted with through-holes 15e, such as square pipes, and the inserted through-holes 15e are fastened to the outer opening edges via square pipe washers 15f (see Figure 6), thereby connecting the large-form support beams 15 arranged in multiple stages spaced apart in the vertical direction. Furthermore, fastening hardware 11d, such as a hook bolt, fastened to fastening holes 11c in the ribs 11b of the steel form panels 11 that form the divided main-body formwork 13 is fastened to the opening edges on the inside (the side of the divided main-body formwork 13) of the through-holes 15b via beam washers 15g (see Figure 6). As a result, in the ground assembly work described below, it becomes possible to form a split form structure 16 by abutting and joining the split main formwork 13 made up of multiple steel formwork panels 11 connected vertically and horizontally to the split support beams 15 arranged in multiple stages (see Figure 4).The length of the split support beam 15 can be adjusted appropriately so that it corresponds to one side of the annular support beam 14 that continues in a rectangular ring shape (see Figure 7) by connecting and joining unit beam materials of a predetermined length together in the longitudinal direction via end connecting plates 15d attached to the ends.

[0022] In this embodiment, at a construction site where a reinforcing reinforced concrete layer is poured around a reinforced concrete pier 50, as shown in Figures 1 and 4, the structure is assembled on the ground in a work area away from the pier 50, for example, so that four split formwork structures 16 are formed by a split main formwork 13 made up of a predetermined number of formwork units 11 arranged vertically and horizontally, supported by multiple parallel split support beams 15, and then abutting and joining the split main formwork 13 to these split support beams 15 as a single unit.

[0023] In other words, in the split formwork structure 16, form units 11 made of a predetermined number of steel formwork panels, each capable of forming, for example, a rectangular split main body formwork 13 of a predetermined size, are arranged in a row and column, for example with their back sides facing up, and these steel formwork panels 11 are connected to each other using locking hardware 11d to form an integrated split main body formwork 13.At the same time, multiple stages of split support beams 15 are extended parallel to each other on the back side of the formed split main body formwork 13, with one flange surface of each beam abutting the tip of the rib 11b of the steel formwork panel 11 (see Figures 4 and 6), and the split main body formwork 13 made of steel formwork panels 11 is connected to these multiple stages of split support beams 15 so that they abut against each other using beam washers 15g and locking hardware 11d such as hook bolts (see Figure 6). This makes it possible to form, by assembling on the ground, four split form structures 16, each of which has a split main body form 13 made up of a plurality of steel form panels 11 arranged lengthwise and crosswise joined integrally to a plurality of split support beams 15 (see Figure 4). Furthermore, with the split support beams 15 installed in multiple stages, the through members 15e are inserted and engaged into the through openings 15b of the channel steel 15a constituting the large form support beam, thereby connecting these multiple stages of split support beams 15 to one another, so that the split form structures 16 can stably maintain their strong shape-retaining rigidity when they are lifted up and erected at the location where concrete is to be poured.

[0024] The four split form structures 16 assembled on the ground are stored in a stacked state, for example, in a section at the construction site away from the pier 50, as shown in Figures 1 and 2. The stored split form structures 16 can be easily lifted up by using a heavy lifting machine 60 such as a crane selected according to the weight of the structure and the size of the work area, and individually erected at the concrete pouring location of the lowest construction rod, where reinforcing bars 54 have been previously placed, for pouring additional concrete to form a reinforcing concrete layer 51, preferably around the lower end portion of the pier 50, which is a reinforced concrete column to be reinforced. As will be described later, the four erected split formwork structures 16 are integrated by joining the four split support beams 15 of each stage at right angles to each other via corner joint pieces 21, preferably having right-angled triangular portions, to form annular support beams 14 of each stage, which preferably continue in a rectangular ring shape in the circumferential direction, using a support beam joint structure 20 (see Figure 3).The four split main body formworks 13 are assembled into a cylindrical shape with a rectangular hollow cross section using the above-mentioned tie rod holes, U-clip holes, etc., locking holes 11c (see Figure 5), and locking hardware 11d, such as U-clips and hook bolts, to form the tubular main body formwork 12 (see Figure 3).This makes it possible to obtain a formwork structure 10 for reinforced concrete columns, in which the annular support beams 14 and tubular main body formwork 12 are integrated.

[0025] In addition, in this embodiment, a continuous cylindrical concrete pouring space 52 of a predetermined width corresponding to the thickness of the reinforced concrete layer 51 to be poured is formed between the inner formwork surface of the steel formwork panel 11 constituting the cylindrical main body formwork 12 of the reinforced concrete column formwork structure 10 thus provided around the periphery, preferably of the lower end portion, of the existing pier 50 and the outer surface of the existing pier 50, as the concrete pouring location for the lowest construction rod. Such cylindrical concrete pouring spaces 52 of a predetermined width can be formed, for example, by supporting spacer separators 53 (see Figure 3) on the concrete surface around the periphery of an existing pier 50, to ensure a predetermined thickness of the reinforcing reinforced concrete layer, using anchors or the like that have been driven into the pier 50 in advance, and attaching them in a balanced arrangement at multiple appropriate locations.By positioning each split formwork structure 16 via these spacer separators 53 and installing it on the outer periphery surrounding the existing pier 50, it becomes possible to precisely maintain cylindrical concrete pouring spaces 52 of a predetermined width corresponding to the thickness of the reinforcing reinforced concrete layer 51 on the outer periphery of the existing pier 50.

[0026] Furthermore, in this embodiment, temporary work scaffolding 55 for various tasks is assembled and installed along each of the four sides of the rectangular cross-sectional pier 50 at the outer periphery, with a predetermined distance between the pier and the outer periphery to allow for the installation of reinforcing bars 54 and split formwork structures 16. The temporary work scaffolding 55 can be preferably formed using, for example, lightweight Darwin scaffolding, which can lift multiple spans as a single unit. The Darwin scaffolding preferably has short ties so that the spans can be divided. Each split formwork structure 16 can be installed on the outside of each of the four sides of the pier 50, as needed, by removing and restoring the work scaffolding on one or two of the work scaffolding 55 installed on the outer periphery of each of the four sides.

[0027] As shown in Figure 3, the four installed split formwork structures 16 have four split support beams 15 attached to them at each stage. These split support beams 15 are joined together at right angles to each other at the four corner joints of adjacent pairs of split support beams 15 using support beam joint structures 20. This joins these split support beams 15 together using corner joint pieces 21 with right-angled triangular portions at each of the four corner joints. This makes it possible to efficiently form a formwork structure 10 for reinforced concrete columns, which includes a cylindrical main formwork 12 assembled into a cylindrical shape with a rectangular hollow cross section of a predetermined height, and annular support beams 14 attached in multiple stages and extending in a rectangular ring shape around the outer periphery of the cylindrical main formwork 12.

[0028] That is, in this embodiment, as described above, the formwork structure 10 for reinforced concrete columns is constructed by assembling the four divided main formworks 13 and divided support beams 15 into four divided formwork structures 16 on the ground in advance, and then erecting them at the concrete pouring location and connecting them as a whole, thereby forming a rectangular cylindrical concrete pouring space 52 by the cylindrical main formwork 12 between the existing pier 50.When the four divided formwork structures 16 are assembled as a whole, the four divided support beams 15 are joined to each other at right angles at the four corner joints of each adjacent pair of divided support beams 15 via corner joint pieces 21 having right-angled triangular portions, as shown in Figure 3, by the support beam joint structure 20, thereby forming a continuous annular support beam 14 in a rectangular ring shape. In this embodiment, the support beam joint structure 20 is such that, at each of the four corner joints where adjacent pairs of divided support beams 15 are joined at right angles, as shown in Figures 8(a) to (c), the end face 17a of one divided support beam 15 is abutted against the end side face 17b in an area spaced from the end face 17a of the other divided support beam 15, and these end side faces 17b, 17b are joined together via a corner joint piece 21 having a pair of abutment plates 21a, 21a arranged at right angles that can abut against these end side faces 17b, 17b, which are attached so as to be fitted from the outside into the right-angle portion between each of the end side faces 17b, 17b of the pair of adjacent divided support beams 15, 15 arranged at right angles, thereby forming a continuous rectangular annular support beam 14.

[0029] In addition, in this embodiment, the formwork units 11 made of steel formwork panels are connected and assembled as a single unit via the divided support beams 15, as described above, to form the divided main body formwork 13.

[0030] Furthermore, in this embodiment, the corner joint piece 21 is designed to join each pair of adjacent split support beams 15 together at right angles at the four corner joints using fastening bolt members 22 that pass through the split support beams 15 and are fastened and fixed.

[0031] 9(a) to 9(c), the corner joint piece 21 constituting the support beam joint structure 20 is a steel joint member having a planar shape of a right-angled equilateral triangle, and is formed by a pair of vertically (horizontally) elongated abutment plate portions 21a, for example, approximately 345 mm long and 129 mm wide, arranged at right angles to each other and joined by welding or the like, and a pair of reinforcing rib plates 21b, also having a right-angled equilateral triangular shape, arranged so as to straddle the upper or lower edge portions of the pair of abutment plates 21a and fitted into the inner right-angle portions of the abutment plates 21a and fixed by welding or the like. Each abutment plate 21a has a plurality of bolt fastening holes 21c formed in its widthwise center at predetermined intervals along its length. These bolt fastening holes 21c are designed to fasten one end of a fastening bolt member 22 to tightly join the abutment plate 21a of the corner joint piece 21 to each end side surface 17b, 17b of a pair of adjacent divided support beams 15, 15.

[0032] To join each pair of adjacent split support beams 15 at right angles using corner joint pieces 21 at the four corner joints of the annular support beam 14, as shown in Figures 3 and 8(a) to (c), with four split formwork structures 16 each erected around the lower end portion of the pier 50, the split support beams 15, 15 of each stage attached to the outside of the split formwork structures 16 are positioned so that the end face 17a of one split support beam 15 abuts against the end side face 17b in an area spaced from the end face 17a of the other split support beam 15 at each corner joint between each pair of adjacent split support beams 15, and these pairs of split support beams 15 are arranged at right angles (see Figure 8(a)). Thereafter, at each corner joint, the corner joint piece 21 is fitted from the outside into the perpendicular portion formed by the end side surfaces 17b of the pair of perpendicularly arranged split support beams 15, 15, so that its pair of abutment plates 21a, 12a are respectively superimposed on the end side surfaces 17b, 17b of the perpendicularly arranged split support beams 15, 15. Then, with the pair of abutment plates 21a, 12a of the corner joint piece 21 respectively overlapped on the end side surfaces 17b, 17b of the split support beams 15, 15, the fastening bolt member 22 is inserted through the bolt fastening holes 21c of the abutment plates 21a, 12a into the gap 15c (see Figure 6) held between the pair of channel steels 15a of the split support beams 15, 15, so that the other end of the fastening bolt member 22 can be positioned so that it protrudes from the end side surface 17b' opposite to the end side surface 17b to which the corner joint piece 21 is joined (see Figure 8(c)).

[0033] As a result, the fastening bolt member 22 inserted through the bolt fastening hole 21c and the gap 15c between the pair of channel steels 15a, 15a of the divided support beams 15, 15 can have one end fastened using a washer or nut to the abutment plate 21a, 21a of the corner connection piece 21 that comes into close contact with the end side surface 17b, 17b of the divided support beam 15, 15 at the right angle on the side where the corner connection piece 21 is located, and the other end can be fastened using a washer or nut to the fastening plate 22a, 22b that comes into close contact with the end side surface 17b', 17b' on the opposite side from the corner connection piece 21. This also makes it possible to firmly fix the corner connection piece 21 to the right angle portion formed by the end side surfaces 17b of the pair of divided support beams 15, 15 that are arranged at a right angle, with the corner connection piece 21 fitted from the outside.

[0034] In this embodiment, each pair of adjacent split support beams 15 is fastened and fixed at four corner joints, each joined at a right angle via the corner joint pieces 21, as described above, preferably using three fastening bolt members 22. In this embodiment, fastening plates 22a, 22b are attached to the end side surface 17b' opposite to the end side surface 17b to which the abutment plates 21a, 12a of the corner joint piece 21 are in close contact, interposed between washers and nuts. The outer fastening plate 22a is disposed on the outer end side surface 17b' opposite to the corner joint piece 21 to which the end surface 17a is in contact. The outer fastening plate 22a is a single, continuous, horizontally elongated plate member capable of simultaneously fastening three fastening bolt members 22, as shown in FIG. 10(a). In addition, the inner fastening plate 22b, which is attached in close contact with the inner end side surface 17b' on the opposite side of the corner connecting piece 21 of the other divided support beam 15 against which the end face 17a abuts, is made up of multiple (two in this embodiment) block-shaped plate members that are arranged in a divided state as shown in Figure 10(b) and can fasten three connecting bolt members 22 in, for example, two locations.

[0035] The inner fastening plates 22b attached in close contact with the inner end side surface 17b' of the other divided support beam 15 against which the end face 17a abuts are formed as multiple, segmented, cross-section plate members, which make it possible to position each of the cross-section inner fastening plates 22b while avoiding interference with the rear-side ribs 11b protruding from the rear surface of the steel form panel 11 of the divided main formwork 13 connected with the ribs 11b abutting the inner end side surface 17b' of the other divided support beam 15. This makes it possible to fasten the other ends of the three fastening bolt members 22 to the inner fastening plates 22b in close contact with the inner end side surface 17b' and with the rear-side ribs 11b of the steel form panel 11 abutting the inner end side surface 17b' in a portion that does not interfere with the rear-side ribs 11b.

[0036] In this embodiment, the above-mentioned support beam joining structure 20 using corner joining pieces 21 connects the four split support beams 15 of each stage of the four split formwork structures 16 together to form continuous rectangular ring-shaped support beams 14, and the split main formwork 13 made up of multiple steel formwork panels 11 arranged vertically and horizontally and supported by the split support beams 15 is integrated by connecting the steel formwork panels 11 at their side ends using locking hardware 11d such as U-clips and hook bolts, making it possible to form a cylindrical main formwork 12 with a rectangular hollow cross-section. As a result, the formwork structure 10 for reinforced concrete columns, which includes the cylindrical main body formwork 12 assembled into a cylindrical shape of a predetermined height and the annular support beams 14 attached in multiple stages and extending in a ring shape in the circumferential direction along the outer periphery of the cylindrical main body formwork 12, is installed at a predetermined height around the lower end portion of the existing pier 50, and a rectangular cylindrical concrete pouring space 52 is formed, maintaining a predetermined distance between it and the lower end portion of the existing pier 50. Furthermore, concrete is poured into the formed cylindrical concrete pouring space 52 at the lower end portion of the pier 50, and a reinforcing concrete layer 51 for reinforcing the lowest construction rod is constructed.

[0037] In this embodiment, the existing pier 50 is, for example, a reinforced concrete column of considerable height, and when the above-mentioned reinforced concrete column formwork structure 10 is used to construct a reinforcing reinforced concrete layer 51 around the pier 50, the following reinforcement method for reinforced concrete columns is implemented, which makes it possible to use the divided main body formwork 13 that makes up the tubular main body formwork 12 in multiple rotations from the bottom to the top of the pier 50, making it possible to efficiently construct a reinforcing reinforced concrete layer 51 around the pier 50 by adding more concrete to the pier 50.

[0038] In other words, a preferred embodiment of the reinforcement method for reinforced concrete columns according to the present invention is a reinforcement method using the above-mentioned tubular main body formwork 12, which is formed into a cylindrical shape of a predetermined height by joining together a plurality of divided main body formworks 13 in the circumferential direction in order to construct a reinforcing reinforced concrete layer 51 around an existing reinforced concrete column, a pier 50, as shown in Figures 11(a) to (c) and 12(a) and (b).The divided main body formworks 13 that make up the tubular main body formwork 12 are formed, as described above, by connecting and arranging a plurality of steel formwork panels 11, which are formwork units, as a single unit via divided support beams 15, and assembling them to a predetermined height, and are designed to be rotated multiple times from the bottom to the top of the existing reinforced concrete column, a pier 50. A cylindrical main body form 12 is installed around the lower end portion of the existing pier 50 (see FIG. 11(a)), and concrete is poured into the cylindrical concrete pouring space 52 held between the existing pier 50 and the cylindrical main body form 12 to form a reinforcing concrete layer 51 for the lowest construction rod (see FIGS. 11(a) and 11(b)). Then, a form sliding process (see FIG. 11) is carried out in which each of the divided main body form 13 of the removed cylindrical main body form 12 is slid away from the formed reinforcing concrete layer 51 for the lowest construction rod while remaining upright. A worker enters the work space 56 between the divided main body formwork 13 and the resulting work space 56 between the divided main body formwork 13 and the bottom reinforcing concrete layer 51 to carry out a formwork surface cleaning process (see Figure 11(c)) in which the inner formwork surface of each divided main body formwork 13 is cleaned, and then a lifting and repurposing process (see Figure 12(a)) in which the divided main body formwork 13 with its inner formwork surface cleaned is lifted upward and re-installed as a component of the tubular main body formwork 12 to form the reinforcing concrete layer 51 of the next layer of construction rods is carried out.

[0039] In this embodiment, the reinforcement method for a reinforced concrete column preferably uses the divided main body formwork 13 converted into the next-stage construction rod in the lifting and conversion step to pour concrete into the cylindrical main body formwork 12 installed around the existing pier 50 and the cylindrical concrete pouring space 52 held between the existing pier 50, thereby forming a reinforcing concrete layer 51 for the next-stage construction rod, and then hangs down each divided main body formwork 13 of the removed cylindrical main body formwork 12 in an upright state to the part of the lowest-stage construction rod, and then lifts up the reinforcing concrete layer 51 of the lowest-stage construction rod formed. The following processes are carried out: a formwork hanging and moving process (see Figure 12(b)) in which the formwork is moved away from the cleat layer 51; a formwork surface re-scraping process (see Figure 12(b)) in which workers enter the work space 56 created between the bottom reinforced concrete layer 51 and scrape the inner formwork surface of each divided main body formwork 13; and a re-hoisting and reuse process in which the divided main body formwork 13 with its inner formwork surface scraped is lifted upward and reinstalled as a component of the tubular main body formwork 12 to form the reinforced concrete layer 51 of the next level of construction rods.

[0040] Furthermore, in this embodiment, as described above, the reinforcement method for reinforced concrete columns involves installing temporary scaffolding 55 around the existing pier 50, which is used when assembling the reinforcing bars 54 and the tubular main body formwork 12, while maintaining space for the tubular main body formwork 12 to be arranged, and preferably, prior to the formwork sliding process or the formwork hanging and moving process, a scaffolding partial removal process (see Figures 11(c) and 12(b)) is carried out in which part of the temporary scaffolding 55 in the part of the lowest construction rod is removed so that the movement of the divided main body formwork 13 is not hindered.

[0041] In this embodiment, as shown in Figure 15, a lifting weight equipment 61 is provided, which is preferably supported on the upper end portion of the installed temporary scaffolding 55 and is composed of, for example, joists, H-shaped steel, beam clamps, shackles, an electric chain block 61a, a chain 61b, etc., and a horizontal pulling equipment 62 is provided, which is supported on the vertical middle portion of the temporary scaffolding 55 and is composed of a manual chain block 62a and a chain 62b, and a roller conveyor 62c installed on the ground surface, etc.

[0042] In the form sliding process, the divided main body formwork 13 is slid away from the formed, lowest reinforced concrete layer 51 by, for example, operating the electric chain hoist 61a and the manual chain hoist 62a. The divided main body formwork 13, which has been removed from the hardened reinforced concrete layer 51, is then slightly lifted by the electric chain hoist 61a. Then, a roller conveyor 62c is laid on the ground surface by inserting one end of the lifted divided main body formwork 13 into a gap between the ground surface and the lower end of the lifted divided main body formwork 13. The electric chain hoist 61a then lowers and places the divided main body formwork 13 in an upright position on the laid roller conveyor 62c. The manual chain hoist 62a is then operated to pull the divided main body formwork 13 along the roller conveyor 62c, sliding it away from the formed, lowest reinforced concrete layer 51, to an area from which the temporary scaffolding has been partially removed, if necessary.

[0043] In addition, in the formwork surface cleaning process, a fairly large work space 56 is formed in an area close to the ground surface between the divided main body formwork 13 that has been slid in the formwork sliding process and the lowest reinforced concrete layer 51, so that workers who enter this work space 56 can easily clean the inner formwork surface of each divided main body formwork 13.

[0044] In the lifting and repurposing step, as shown in Figure 16, for example, an electric chain hoist 61a and a manual chain hoist 62a are operated to lift the temporary scaffolding 55 so as to avoid it, and the divided main body formwork 13, whose inner formwork surface has been cleaned in the formwork surface cleaning step, can be reused and reinstalled as a component part of the cylindrical main body formwork 12 for forming the reinforcing concrete layer 51 of the next stage of construction rods. The temporary scaffolding 55, which was partially removed prior to the formwork sliding step, can also be restored as appropriate after the lifting and repurposing step.

[0045] In the formwork suspending and moving process, after the reinforced concrete layer 51 of the next stage of construction rods is formed using the divided main body formwork 13 that was converted into the next stage of construction rods in the hoisting and converting process, for example, by operating the electric chain block 61a and the manual chain block 62a, each divided main body formwork 13 of the tubular main body formwork 12 is removed, and the removed divided main body formwork 13 is suspended in an upright state down to the part of the lowest stage of construction rod and moved away from the formed lowest stage of reinforced concrete layer 51. After temporarily suspending the divided main body formwork 13 above the roller conveyor 62c, the manual chain block 62a can be operated to slide it along the roller conveyor 62c to an area away from the formed lowest stage of reinforced concrete layer 51, from which some of the temporary scaffolding has been removed, as necessary.

[0046] In the formwork surface re-scraping process, as in the formwork surface cleaning process, a fairly large work space 56 is formed in an area close to the ground surface between the divided main body formwork 13 moved in the formwork hanging and moving process and the lowest reinforced concrete layer 51, so that workers who enter this work space 56 can easily clean the inner formwork surface of each divided main body formwork 13.

[0047] In the re-lifting and repurposing process, similar to the lifting and repurposing process, for example, an electric chain block 61a and a manual chain block 62a are operated to lift the divided main body formwork 13 while avoiding the temporary scaffolding 55, and the divided main body formwork 13 whose inner formwork surface has been cleaned in the formwork surface re-cleaning process can be reused and reinstalled as a component part of the cylindrical main body formwork 12 for forming the reinforcing concrete layer 51 of the next stage of construction rods.

[0048] As a result, according to the reinforcement method for reinforced concrete columns of this embodiment, even if the existing reinforced concrete column, or pier 50, to be reinforced is a concrete column of considerable height, the divided main body formwork 13 constituting the cylindrical main body formwork 12 of a predetermined height can be easily scraped and reused from the lowest construction rod to the next construction rod, or as the divided main body formwork 13 for the next next construction rod, thereby enabling the cylindrical main body formwork 12 to be installed around the pier 50 efficiently while reducing the amount of materials used, thereby making it possible to effectively reinforce the existing pier 50 with the added reinforced concrete layer 51. Furthermore, according to the reinforcement method for reinforced concrete columns of this embodiment, when adding reinforced concrete layer 51 to reinforce the existing reinforced concrete column, or pier 50, it is possible to reduce the effort required for processing and assembling formwork on site, and it is possible to more rationally reinforce the concrete column, or pier 50, thereby making it possible to effectively reduce construction costs.

[0049] In addition, in this embodiment, the reinforcement method for a reinforced concrete column preferably includes installing a cylindrical main body form 12 around the lower end portion of an existing pier 50, pouring concrete into a cylindrical concrete pouring space 52 held between the existing pier 50 and the cylindrical main body form 12, forming a reinforcing concrete layer 51 of the lowest construction rod, and after removing the divided main body form 13, as shown in Figure 11 (c) and Figures 13 (a) and (b), placing a small amount of concrete remaining at a predetermined height on the surface of the upper end portion of the reinforcing concrete layer 51 of the lowest construction rod in the part where the divided main body form 13 has been removed. It is possible to carry out a height-adjustment support hardware installation process in which height-adjustment support hardware 58 (see Figures 14(a) and (b)) is installed to engage and support the lower end of the divided main body formwork 16 using at least two embedded anchors 57 (see Figure 13(b)) as support members, and a formwork conversion assembly process (see Figure 12(a)) in which the removed divided main body formwork 16 is lifted and, with its lower end engaged to the height-adjustment support hardware 58 (see Figure 13(b)), a tubular main body formwork 12 for forming the reinforcing concrete layer 51 of the next layer of construction rods is assembled.

[0050] 14(a) and 14(b), the height-adjustable support hardware 58 is a fastening hardware made of, for example, an angle iron with an L-shaped cross section, and has a joint surface 58a, which is one surface that is placed in close contact with the surface of the reinforced concrete layer 51, formed with a fastening slot 58c to which an adjustment plug 59a of a Form-Tie (registered trademark) 59 is fastened. The fastening slot 58c is formed to extend linearly at an angle with respect to a support surface 58b to which the lower end of the divided main body form 13 made of the steel form panel 11 is fastened. This makes it possible to appropriately adjust the height of the support surface 58b by changing the position of the fastening slot 58c to fasten the adjustment plug 59a that is screwed into the embedded anchor 57 (see FIG. 13(b)).

[0051] Furthermore, in this embodiment, the reinforcement method for a reinforced concrete column preferably uses the divided main body formwork 13 converted into the next stage of construction rods in the formwork conversion assembly process, and pours concrete into the cylindrical main body formwork 12 installed around the existing pier 50 and the cylindrical concrete pouring space 52 of concrete held between the existing pier 50 to form the reinforcing concrete layer 51 of the next stage of construction rods, and after the divided main body formwork 16 is removed, a predetermined amount of concrete is poured into the upper end portion of the reinforcing concrete layer 51 of the next stage of construction rods in the part where the divided main body formwork 13 has been removed. It is possible to carry out a height adjustment support hardware reinstallation process in which height adjustment support hardware 58 (see Figures 14(a) and (b)) is installed to engage and support the lower end of the divided main body formwork 13 using at least two embedded anchors 57 (see Figure 13(b)) left at the height position as support members, and a formwork reuse assembly process in which the demolded divided main body formwork 16 is lifted and, with its lower end engaged to the adjustment support hardware 58, a tubular main body formwork 12 is assembled to form the reinforcing concrete layer 51 of the next layer of construction rods.

[0052] Furthermore, in this embodiment, the reinforcement method for reinforced concrete columns involves installing temporary scaffolding 55 around the existing pier 50, as described above, to be used when assembling the reinforcing bars 54 and the cylindrical main body formwork 12, while maintaining space for the cylindrical main body formwork 12 to be arranged, and preferably using a lifting weight equipment 61 supported on the upper end part of the installed temporary scaffolding 55, the divided main body formwork 13 to be demolded and reused can be lifted in the formwork conversion assembly process or formwork re-conversion assembly process.

[0053] The present invention is not limited to the above-described embodiment and various modifications are possible. For example, the reinforced concrete column reinforced by the reinforcement method for a reinforced concrete column of the present invention does not necessarily have to be a bridge pier. The reinforced concrete column reinforcement method of the present invention can also be used to reinforce reinforced concrete columns that constitute various structures. The reinforced concrete column does not necessarily have to have a rectangular cross-sectional shape, but may have other cross-sectional shapes such as a circular or elliptical shape. The cylindrical main body formwork using the divided main body formwork can be assembled and used to form a cylindrical shape with a hollow cross-section other than a rectangular shape, such as a circular or elliptical shape, and the annular support beam can be attached continuously in the circumferential direction to form a circular or elliptical shape other than a rectangular ring. [Explanation of symbols]

[0054] 10. Formwork structure for reinforced concrete columns 11 Steel formwork panel (formwork unit) 11a Face plate 11b Rib 11c Locking hole 11d Locking hardware 12 Cylindrical main body formwork 13 Split main body formwork 14 Annular support beam 15 Split support beam 15a channel steel 15b Through opening 15c gap 15d End connecting plate 15e through material 15f Square Pipe Washer 15g beam washer 16 Split formwork structure 17a End face of split support beam 17b Side of end of split support beam 17b' The end side opposite to the end side to which the corner joint piece is joined 20 Support beam joint structure 21 Corner joint piece 21a Contact plate 21b Reinforced rib plate 21c Bolt fastening hole 22 Fastening bolt member 22a Outer fastening plate 22b Inner fastening plate 50 Bridge pier (reinforced concrete column) 51 Reinforced concrete layer 52 Concrete pouring space 53 Separator 54 Reinforced concrete 55 Work scaffolding 56 workspace 57 Buried anchor 58 Height adjustment support hardware 58a Joint surface part 58b Support surface part 58c Fastening slot 59 Form Tie (registered trademark) 59a Adjustment plug 60 Lifting Machine 61 Yang Chong Equipment 61a Electric Chain Hoist 61b Chain 62 Horizontal pulling equipment 62a Manual Chain Block 62b Chain 62c Roller Conveyor

Claims

1. A reinforcement method for reinforced concrete columns using a cylindrical main formwork formed into a cylindrical shape of a predetermined height by joining together multiple divided main formworks in the circumferential direction to construct a reinforcing reinforced concrete layer around an existing reinforced concrete column. The divided main body formwork constituting the cylindrical main body formwork is formed by assembling a plurality of formwork units at a predetermined height, which are connected together via support beams, and is adapted to be rotated multiple times from the bottom to the top of an existing reinforced concrete column. The cylindrical main body formwork is installed around the lower end portion of the existing reinforced concrete column, and concrete is poured into the cylindrical concrete pouring space held between the existing reinforced concrete column and the cylindrical main body formwork to form a reinforcing concrete layer for the lowest construction rod. This reinforcement method for reinforced concrete columns involves the following steps: a form sliding step in which each of the divided main body formworks of the removed cylindrical main body formwork is slid, while remaining upright, away from the formed lowest reinforced concrete layer; a form surface cleaning step in which a worker enters the work space created between the divided main body formwork and the lowest reinforced concrete layer thereby and cleans the inner form surface of each of the divided main body formworks; and a lifting and repurposing step in which the divided main body formworks whose inner form surface has been cleaned are lifted upward and re-installed as constituent members of the cylindrical main body formwork for forming the reinforcing concrete layer of the next layer of construction rods.

2. Using the divided main body formwork converted to the next stage of construction rods in the lifting and conversion process, concrete is poured into the cylindrical concrete pouring space held between the cylindrical main body formwork installed around the existing reinforced concrete column and the existing reinforced concrete column, thereby forming a reinforcing concrete layer for the next stage of construction rods. After that, the divided main body formworks of the removed cylindrical main body formwork are hung down in an upright state to the part of the lowest stage of construction rods, and the reinforcing concrete layer formed for the lowest stage is 2. The method for reinforcing a reinforced concrete column according to claim 1, further comprising the steps of: a formwork suspending and moving process in which the formwork is moved away from the lowermost layer of reinforced concrete; a formwork surface re-scraping process in which workers enter the work space created between the lowermost layer of reinforced concrete and scrape the inner formwork surfaces of each of the divided main formworks; and a re-hoisting and repurposing process in which the divided main formworks whose inner formwork surfaces have been scraped are lifted upward and reinstalled as constituent members of the cylindrical main formwork for forming the reinforcing concrete layer of the next layer of construction rods.

3. 3. A reinforcement method for a reinforced concrete column according to claim 1 or 2, wherein temporary scaffolding used when assembling the reinforcing bars and the cylindrical main body formwork is installed around the existing reinforced concrete column while maintaining space for the cylindrical main body formwork to be arranged, and prior to the formwork sliding step or the formwork hanging and moving step, a scaffolding partial removal step is carried out in which part of the temporary scaffolding in the part of the lowest construction rod is removed so that it does not interfere with the movement of the divided main body formwork.

4. A reinforcement method for reinforced concrete columns as described in claim 1 or 2, wherein the existing reinforced concrete column has a rectangular cross-sectional shape, and the cylindrical main body formwork made up of multiple divided main body formworks is assembled into a cylindrical shape with a rectangular hollow cross-section.

5. 3. A reinforcement method for reinforced concrete columns as described in claim 1 or 2, wherein the cylindrical main body formwork has an annular support beam formed by continuously integrating the support beams of multiple divided main body formworks, which are attached in multiple stages and extend in a ring shape circumferentially along the outer periphery of the cylindrical main body formwork, so that the load imposed by the internal pressure of the concrete poured inside is supported from the outside by the annular support beam.

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