MOLD STRUCTURE FOR CAVITY FORMED FOR FILLING OF CEMENT FILLER BETWEEN STEEL GIRDER UPPER FLANGE UPPER SURFACE AND PCa SLAB LOWER SURFACE AND SLAB STRUCTURE CONSTRUCTION METHOD USING THE MOLD STRUCTURE

Abstract

To provide a mold structure allowing a cement-based filler to be filled over the whole width of a steel girder upper flange upper surface and easy attachment and detachment to and from a steel girder upper flange and PCa slab.SOLUTION: A mold structure is a mold structure including a mold body 5 forming a cavity formed for filling of a cement-based filler between a steel girder 1 upper flange upper surface 1A and a PCa slab lower surface, being provided with a mold mount plate 7 on which the mold body is mounted, wherein a part of a side on which the mold body is mounted is arranged so as to contact a lower surface of the steel girder upper flange except at least an area on which the mold body is mounted, and the mold structure comprises a magnet unit 91 and a mount plate support part provided on the magnet unit to support the mold mount plate by magnetic attraction between the magnet unit and the lower surface of the steel girder upper flange.SELECTED DRAWING: Figure 4B

Description

[Technical Field]

[0001] The present invention relates to a formwork structure used to form a gap to be filled with cement-based filler between the upper surface of the steel girder upper flange and the underside of the PCa deck (hereinafter referred to as the "joint") when constructing a deck structure by laying a precast concrete deck (hereinafter referred to as the "PCa deck") on the steel girder upper flange in bridge superstructure, and a deck structure construction method using the same. [Background technology]

[0002] When constructing a deck structure by laying a PCa deck on the steel girder upper flange of a bridge superstructure, an appropriate gap is left between the top surface of the steel girder upper flange and the underside of the PCa deck, and this gap is filled with cement-based filler to form a joint and integrate the two. Generally, through-holes are drilled from the top to the bottom at the position of the steel girder upper flange of the PCa deck, and the PCa deck is placed on the steel girder upper flange, leaving a gap between the underside of the PCa deck and the top surface of the steel girder upper flange so that the through-hole is positioned on the steel girder upper flange. Next, stud dowels are melt-spliced ​​onto the top surface of the steel girder upper flange through the through-holes in the PCa deck, and cement-based filler is injected through the through-holes in the PCa deck and allowed to harden.

[0003] When injecting cement-based filler into the gap between the top surface of the steel girder upper flange and the underside of the PCa deck, a formwork is required to surround the gap to prevent the cement-based filler from leaking out. The formwork materials used include L-shaped members, sponge packing, and special metal fittings using leaf springs.

[0004] For example, Non-Patent Document 1 discloses a method of using sole sponge as a formwork. The sole sponge comes into close contact with the upper surface of the steel girder and the underside of the PCa deck, which can prevent mortar from leaking from gaps in the flange width direction.

[0005] Patent Document 1 also discloses a method in which an insert is embedded in the underside of a PCa deck slab, a horizontal end thick member is supported on a mounting bolt with one end attached to this insert, and a formwork retainer is fixed to the horizontal end thick member to hold down the formwork material and prevent leakage of cement-based filler from voids.

[0006] Patent Document 2 discloses a method in which elastic formwork materials are placed on both ends of the upper surface of a steel girder upper flange, and a cement-based filler is filled between the elastic formwork materials on both ends. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-073847 [Patent Document 2] Japanese Patent Application Publication No. 10-131125 [Non-patent literature]

[0008] [Non-Patent Document 1] Precast PC Deck Construction Manual, March 2004 (pp. 34, 46), published by the Japan Bridge Construction Association Summary of the Invention [Problem to be solved by the invention]

[0009] However, the method of fixing formwork materials disclosed in Patent Document 1 requires complicated work, such as embedding inserts into the underside of the PCa deck slab and supporting the horizontal end thick material on mounting bolts with one end attached to the insert, which makes attachment and detachment time-consuming and may result in an extension of the construction period. In the method of fixing formwork materials disclosed in Patent Document 2, elastic formwork materials are placed on both ends of the upper surface of the steel girder upper flange, so the cement-based filler does not spread across the entire width of the upper surface of the steel girder upper flange, reducing the strength of the ``joint.'' Furthermore, polyethylene resin foam is often used for sole sponges, but its long-term durability is not guaranteed and it may deteriorate and fall off over time. It also lacks heat resistance and is not resistant to fire damage. While it is possible to replace the filler with a different material, such as a sealant, after it hardens, this process requires additional cost and effort.

[0010] In view of the above circumstances, the present invention aims to provide a formwork structure that can fill cement-based filler across the entire width of the upper surface of the steel girder upper flange and that can be easily attached and detached to the steel girder upper flange and PCa deck slab, and a method for constructing a deck structure using this formwork structure. [Means for solving the problem]

[0011] In order to achieve the above object, the formwork structure of the present invention comprises: A formwork structure including a formwork body that forms a gap between the upper surface of the steel girder upper flange and the lower surface of the PCa deck slab into which a cement-based filler is filled, A form mounting plate on which the form body is placed is provided, The formwork mounting plate is arranged so that a part of the surface on which the formwork body is placed is in contact with the lower surface of the steel girder upper flange, except for at least the area on which the formwork body is placed; And the formwork structure is A magnet unit, The magnet unit has a plate support portion that is provided on the magnet unit and supports the formwork plate by magnetic adhesion between the lower surface of the steel girder upper flange and the magnet unit.

[0012] The magnet unit is configured so that magnetic attraction with the underside of the upper flange of the steel girder can be switched on and off.

[0013] According to the present invention, the formwork mounting plate is supported by magnetic attraction between the underside of the steel girder upper flange and the magnet unit, so the formwork structure can be easily installed and removed without the need for complicated work such as embedding inserts or bolts into structures such as PCa deck slabs, and cement-based filler can be filled across the entire width of the upper surface of the steel girder upper flange, thereby improving the strength of the joint. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view of the formwork structure of the present embodiment, viewed obliquely from below. [Figure 2] FIG. 2 is a side view of FIG. 1 as seen from the girder direction. [Figure 3] FIG. [Figure 4A] FIG. 2 is a diagram showing an example of the configuration of the mounting plate support means 9, and is a side view showing the formwork mounting plate 7 in an unfixed state. [Figure 4B] 10 is a diagram showing an example of the configuration of the mounting plate support means 9, and is a side view showing the fixed state of the form mounting plate 7. FIG. [Figure 5] 10 is a diagram showing a configuration for switching on and off the magnetic attraction of the magnet unit 91 in the mounting plate supporting means 9. FIG. [Figure 6] FIG. 10 is a side view showing a mounting plate support means 9a having another configuration. [Figure 7] 10 is a side view showing the stage in which a formwork mounting plate 7 is fixed to the underside of the upper flange 1A of a steel girder 1 by a mounting plate support means 9 in the construction procedure of a deck structure. [Figure 8] This is a side view showing the stage in the construction procedure for the deck structure in which the PCa deck 3 is placed on the upper flange 1A of the steel girder 1 and the formwork main body 5 with a gap 100 therebetween. [Figure 9] FIG. 1 is a side view showing the stage of melt-setting stud dowels 11 in the construction procedure for the deck structure. [Figure 10] FIG. 10 is a side view showing the stage of filling voids and through-holes with cement-based filler in the construction procedure of the deck structure. [Figure 11]10 is a side view showing the stage of dismantling and removing the mounting plate fixing means 9a, formwork mounting plate 7, and formwork main body 5 in the construction procedure of the deck structure. [Figure 12] FIG. 10 is a perspective view for providing additional explanation of the configuration of the magnet unit 91. [Figure 13] 13 is a cross-sectional view showing a state in which the magnetic attraction action of the magnet unit 91 of FIG. 12 is off. FIG. [Figure 14] 13 is a cross-sectional view showing the magnetic attraction of the magnet unit 91 of FIG. 12 in an ON state. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the formwork structure of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of the formwork structure of this embodiment as seen obliquely from below, FIG. 2 is a side view of FIG. 1 as seen from the girder direction, and FIG. 3 is a perspective view showing the formwork body. In these figures, reference numeral 1 denotes a steel girder, specifically an I-section steel girder 1. Note that the present invention is not necessarily limited to the use of an I-section steel girder 1, and any girder having at least an upper flange and a horizontal top surface of the upper flange may be used.

[0016] The PCa deck 3 is laid on the upper flange 1A of the steel girder 1 via a cement-based filler such as non-shrink mortar that is filled in the gap 100 between the upper flange 1A of the steel girder 1 and the underside of the PCa deck 3. The formwork structure of this embodiment includes a formwork main body 5 that prevents the cement-based filler from leaking out of the gap 100 between the upper surface of the upper flange 1A of the steel girder 1 and the underside of the PCa deck 3, a formwork mounting plate 7 on which the formwork main body 5 is placed, and a mounting plate support means 9 that has a magnet unit 91 (see Figures 4(A) and (B)) and detachably supports the formwork mounting plate 7 by magnetically attaching it to the underside 1A of the upper flange of the steel girder 1 and the magnet unit 91.

[0017] FIG. 3 is a perspective view showing an example of the formwork body 5. In this embodiment, the formwork body 5 is made of an elastic material, such as sole sponge. The formwork body 5 is not limited to being made entirely of elastic sole sponge; it may be made of any material that allows the contact surfaces between the upper surface of the upper flange 1A of the steel girder 1 and the underside of the PCa deck 3 to closely adhere to each other and prevent the filler from leaking out. For example, only the pressure-contact portions between the upper surface of the upper flange 1A of the steel girder 1 and the underside of the PCa deck 3 may be made of an elastic material such as sole sponge. For example, as shown in FIG. 3, the formwork body 5 made of sole sponge may be made by combining multiple sole sponge materials in a rectangular planar shape to surround the four sides of the void. Using such a combination of sole sponge materials in a rectangular planar shape facilitates installation and positioning and prevents the cement-based filler from leaking out in all directions.

[0018] Here, as shown in Figure 4(A), it is desirable to position the formwork body 5 so that the inner surface 51 of the formwork body 5 along the girder direction is in contact with the outer end surface 11 along the girder direction of the upper flange 1A of the steel girder 1, in order to prevent leakage of cement-based filler from the void 100.

[0019] Figures 4(A) and (B) are diagrams showing an example of the configuration of the mounting plate support means 9, where Figure 4(A) shows the formwork mounting plate 7 in an unfixed state, and Figure 4(B) shows the formwork mounting plate 7 in a fixed state. The formwork mounting plates 7 are arranged to partially overlap each other so that part of the surface on which the formwork body 5 is placed is in contact with the underside of the upper flange 1A of the steel girder 1. As described above, the formwork body 5 is arranged so that the inner surface 51 of the formwork body 5 along the girder direction is in contact with the outer end surface 11 along the girder direction of the upper flange 1A of the steel girder 1, and therefore it is preferable that the formwork mounting plates 7 protrude outward from the outer end surface 11 along the girder direction of the upper flange 1A of the steel girder 1 by at least the width over which the formwork body 5 is placed.

[0020] 4(A) and 4(B), the mounting plate support means 9 includes a flat base 93, a magnet unit 91 fixed to the upper surface of the base 93, a threaded stand 95 that is movable in a direction penetrating the thickness of the base 93, and a vice 97 for manually rotating the threaded stand 95 around its axis. More specifically, the base 93 is provided with a hole 93A through which the shaft 95A of the threaded stand 95 passes, and the inner circumferential surface of this hole 93A is provided with a female thread that screws into a male thread formed on the outer circumferential surface of the shaft 95A of the threaded stand 95. When the threaded stand 95 is rotated around its axis by rotating the vice 97, the threaded stand 95 moves up or down on the base 93. A base holder 95B is provided at the upper end of the screwed stand 95, and when the screwed stand 95 moves upward on the base 93, the base holder 95B comes into contact with the underside of the formwork mounting plate 7 and presses it upward, pressing the formwork mounting plate 7 against the underside of the upper flange 1A of the steel girder 1. As a result, the formwork mounting plate 7 is fixed in a state where it is sandwiched between the base holder 95B of the screwed stand 95 and the underside of the upper flange 1A of the steel girder 1.

[0021] As shown in FIG. 5 , the magnet unit 91 includes a permanent magnet (not shown) therein and has a magnetic attraction surface A that attracts the upper flange 1A of the steel girder 1, which is the target, through the action of magnetic force. The magnet unit 91 is provided with a knob 99 (operation unit) that can be manually rotated, and the magnetic attraction effect can be switched on and off depending on the rotation position of the knob 99. An example of a magnet unit that can switch the magnetic attraction effect on and off in this way is the Jitto 3025361, and its configuration and operation will be described later. The present invention is not limited to this magnet unit, and any magnet unit that has a magnetic attraction surface that attracts the upper flange 1A of the steel girder 1, which is the target, through the action of magnetic force and is configured to be able to switch the magnetic attraction effect on and off is acceptable.

[0022] Another mounting plate support means 9a for magnetically fixing the formwork mounting plate 7 to the upper flange 1A of the steel girder 1 is shown in Figure 6. This mounting plate support means 9a is a magnet unit 91 provided with a gripping portion 98 that supports the formwork mounting plate 7. When dismantling the formwork, the magnetic attraction action of the magnet unit 91 is switched off, and then the formwork mounting plate 7 and mounting plate support means 9a can be separated horizontally.

[0023] Next, a method for constructing a deck structure using the above-mentioned formwork structure will be described. First, as shown in Figure 7, a formwork mounting plate 7 is fixed to the underside of the upper flange 1A of the steel girder 1 by a mounting plate support means 9. Next, as shown in Figure 8, the PCa slab 3 is placed on the upper flange 1A of the steel girder 1 via a height-retaining jig (not shown). Here, by using a height-retaining jig whose height is slightly lower than that of the formwork main body 5, the formwork main body 5 is slightly compressed in the vertical direction by the weight of the placed PCa slab 3, and the formwork main body 5 is stably held between the PCa slab 3 and the upper flange 1A. The through holes 3A provided in the PCa slab 3 for injecting cement-based filler into the gaps 100 are also filled with cement-based filler.

[0024] Next, as shown in Fig. 9, stud dowels 11 are melt-inserted onto the upper surface of the upper flange 1A of the steel girder 1 through the through holes 3A in the PCa deck 3, and then, as shown in Fig. 10, cement-based filler 12 is injected into the space 100 and through the through holes 3A through the through holes 3A. After the cement-based filler 12 has hardened, the magnetic attraction action of the magnet units 91 of the mounting plate support means 9 is switched off, and the mounting plate support means 9, formwork mounting plate 7, and formwork main body 5 are dismantled and removed, as shown in Fig. 11.

[0025] Next, a supplementary explanation will be given of the configuration of the magnet unit 91 that can switch the magnetic attraction action on and off. As shown in Figure 12, this magnet unit 91 consists of a magnet holder outer frame 102 with a cylindrical magnetized member accommodating hole 105 formed therein, and a magnetized member 103 rotatably accommodated in the magnetized member accommodating hole 105. The upper and lower central portions of the magnet holder outer frame 102 are non-magnetic portions 106A and 106B. The magnetized member 103 consists of a hexagonal prism-shaped rotor portion 110 made of a magnetic material, and permanent magnets 111 attached to the side surfaces of the rotor portion 110 and extending along the longitudinal direction of the rotor portion 110. The permanent magnets 111 are elongated along the longitudinal direction of the rotor portion 110 and are attached to two adjacent side surfaces 10a, 10b, 10c, and 10d located on both ends of the magnetization direction Y of the magnetized member 103. When the magnetization direction Y of the magnetized member 103 is aligned with the direction connecting the pair of nonmagnetic portions 106A and 106B, magnetic flux B does not cross the magnetically attracted surface 107, resulting in a self-closing state. This demagnetizes the magnetically attracted surface 107, and the magnetically attracted surface 107 is not attracted to the opposing surface (see FIG. 13). When the magnetized member 103 is rotated 90 degrees so that the magnetization direction Y of the magnetized member 103 is perpendicular to the direction connecting the pair of nonmagnetic portions 106A and 106B, magnetic flux B crosses the magnetically attracted surface 107, causing the magnetically attracted surface 107 to be magnetized, and the magnetically attracted surface 107 is attracted to the opposing surface (see FIG. 14). This completes the supplementary explanation of the configuration of the magnet unit 91, which can switch the magnetic attraction on and off.

[0026] As described above, according to this embodiment, the formwork support plate 7 on which the formwork main body 5 is placed can be detachably fixed to the steel girder upper flange 1A simply by switching the magnetic attraction of the magnet unit 91 of the support plate support means 9 on and off. This eliminates the need to embed anchors or bolts in structures such as the PCa deck 3 to secure the formwork support plate 7, facilitating the installation and removal of the formwork structure and shortening the construction period. Furthermore, since the cement-based filler can be filled across the entire width of the upper surface of the steel girder upper flange, the strength of the cement-based filler can be improved. Furthermore, since the support plate support means 9 is designed to support the formwork support plate 7 from below, the risk of the formwork main body 5 and formwork support plate 7 falling off is significantly reduced. [Explanation of symbols]

[0027] 1 steel girder 1A Upper flange 3 PCa floor slab 5 Formwork body 7 Formwork mounting plate 9. Mounting plate support means 91 Magnet unit 99 Knob 100 void

Claims

1. A formwork structure including a formwork body that forms a gap between the upper surface of the steel girder upper flange and the lower surface of the PCa deck slab into which a cement-based filler is filled, A form mounting plate on which the form body is placed is provided, The formwork mounting plate is arranged so that a part of the surface on which the formwork body is placed is in contact with the lower surface of the steel girder upper flange, except for at least the area on which the formwork body is placed; And the formwork structure is A magnet unit, a mounting plate support portion provided in the magnet unit and supporting the formwork mounting plate by magnetic attachment between the lower surface of the steel girder upper flange and the magnet unit; Formwork structure.

2. 2. The formwork structure according to claim 1, The magnet unit is configured so that magnetic attraction with the lower surface of the upper flange of the steel girder can be switched on and off. Formwork structure.

3. A method for constructing a deck structure using the formwork structure of claim 1 or 2.

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