Method to install temporary construction support

Abstract

To provide a temporary construction support and a method to install the temporary construction support, which can prevent occurrence of punching shear damage by optimizing the size of a lower base plate or an upper base plate so that adjacent reinforcing bars are included in the range of a punching shear.SOLUTION: A temporary construction support 1 includes a lower column 10 with a lower pipe section 11 and a lower base plate 13 provided at the lower end of the lower pipe section, and an upper column 50 with an upper pipe section 51 and an upper base plate provided at the upper end of the upper pipe section, and is structured as such that the upper pipe section is inserted into the lower pipe section and the distance between the lower base plate and the upper base plate is adjustable, and erected between upper and lower slabs of a building to be dismantled, and the sizes of the lower base plate and the upper base plate are configured so that multiple adjacent parallel reinforcing bars can fit within the range of punching shear for the slabs.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a temporary support for supporting a slab made of reinforced concrete and a method for installing the temporary support when demolishing a building or the like.

Background Art

[0002] When performing demolition work on buildings such as buildings, it is often the case that a method is adopted in which a heavy machine is used and the building is sequentially demolished from the upper floor to the lower floor. In that case, it is difficult to support the load by the heavy machine or the like only with the strength of the floor (slab) of the building to be demolished. Therefore, a temporary support for temporary construction is erected between the upper and lower slabs on the lower floor where the heavy machine is used for reinforcement. Further, when installing this temporary support, in order to prevent punching shear failure that would punch out the slab, generally, while checking the reinforcement drawing, the punching shear range (the range of the surface that spreads obliquely at 45 degrees from the position where the upper base plate abuts on the slab) exerted by the base plates (seat plates) provided above and below the temporary support is positioned so that the positions of the reinforcing bars inside the concrete are included. In this regard, for example, a temporary support for temporary construction aimed at weight reduction and durability improvement as shown in Patent Document 1 is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional temporary construction support, the length of one side of the outer edge of the base plate is relatively small, about 140 to 160 mm. If the installation location of the temporary construction support is displaced for some reason, the steel bars will fall out of the punching shear range by the temporary construction support, and there is a risk that only the concrete will support the load. In this case, there is a risk of punching shear failure of the slab, which is dangerous.

[0005] This is because the center distance between adjacent main steel bars should originally be 200 mm or less. However, in old buildings built from the 1950s to the 1960s, for example, in order to reduce the amount of steel bars used, if there is no problem in structural calculation, the center distance between adjacent main steel bars is increased, for example, to 220 mm or the like. Also, in the central part of the slab in the horizontal direction, the upper steel bars may be omitted by adopting bent bars or cutting the upper end steel bars. Furthermore, this is due to adverse conditions such as the cover thickness to the steel bars at that time being 20 mm depending on the location (see Fig. 10). Moreover, under such adverse conditions, since there is a risk of punching shear failure, the slab cannot support a high load, and it was necessary to increase the number of temporary construction supports to a certain extent.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to provide a temporary construction support and an installation method of the temporary construction support in which, by optimizing the size of the lower base plate or the upper base plate, the steel bars adjacent to the punching shear range can enter, and the occurrence of punching shear failure can be suppressed. Another object of the present invention is to reduce the number of temporary supports per unit area of the slab.

Means for Solving the Problems

[0007] The temporary construction support of the present invention comprises a lower column having a lower pipe portion and a lower base plate provided at the lower end of the lower pipe portion, an upper column having an upper pipe portion and an upper base plate provided at the upper end of the upper pipe portion, A temporary support that is erected between the upper and lower slabs of a building to be disassembled, in which the upper pipe portion is inserted into the lower pipe portion and the distance between the lower base plate and the upper base plate is adjustable. The sizes of the lower base plate and the upper base plate are configured such that a plurality of parallel and adjacent reinforcing bars enter the range of the punching shear with respect to the slab.

[0008] A preferred example of the temporary support of the present invention is At least the upper base plate of the lower base plate and the upper base plate is rectangular, and the length of one side is 170 mm to 200 mm.

[0009] A preferred example of the temporary support of the present invention is At least the upper base plate of the lower base plate and the upper base plate is rectangular, and the length of the diagonal is 226 mm to 283 mm.

[0010] According to these temporary supports of the present invention, the upper base plate of the temporary support can support a plurality of parallel and adjacent (hereinafter, may be simply referred to as "adjacent") reinforcing bars, and can support the slab with a high load. Also, even if the position where the temporary support is installed is displaced, the supporting force by the temporary support reaches at least one reinforcing bar. Furthermore, by increasing the area of the upper base plate, punching shear failure is less likely to occur. By these, the occurrence of punching shear failure can be suppressed.

[0011] Note that, as shown in Fig. 15, for the lower base plate 13, since the range of the punching shear p11 extends downward from the upper surface of the slab 72 and the lower end bars 70a, 70b, 70c of the slab 70 are basically not omitted, it is considered that a plurality of adjacent bars 70a, 70b, 70c enter the range of the punching shear p11 unless the conditions are extremely bad. For this reason, for reasons such as appearance and the difficulty of punching shear failure due to an increase in the area of the lower base plate, it is preferable to make the lower base plate have the same configuration as the upper base plate. However, it is considered that there are few problems even if they are not exactly the same configuration.

[0012] Also, at least the upper base plate among the lower base plate and the upper base plate being rectangular means that it is intended to be rectangular when viewed from the bottom or in plan view, but it does not need to be an exact rectangle, and it is sufficient if it is approximately rectangular. That is, it includes cases where chamfering or the like is applied to the corners of the rectangle, or all or part of the outer sides are curved or bent so that the outer sides are concave or convex when viewed from the bottom or in plan view (the same applies to the following inventions). Also, the diagonal of the lower base plate or the upper base plate that forms a rectangular shape is intended to be the dimension excluding the chamfered or the like part when chamfering or the like is applied to the corners of the lower base plate or the upper base plate. That is, if there is chamfering or the like at the corners, the diagonal dimension is shortened accordingly (the same applies to the following inventions).

[0013] The temporary construction support of the present invention is a temporary construction support erected between the upper and lower slabs of a building to be demolished, a lower column including a lower pipe portion, a lower base plate provided at the lower end of the lower pipe portion, and a lower pipe locking portion provided at the upper end of the lower pipe portion, an adjustment nut rotatably locked to the lower pipe locking portion, a screw pipe provided with an external thread portion on the outer peripheral surface, a pin receiving cylinder portion provided above the external thread portion, and a first pin hole penetrating from one outer periphery to the other outer periphery in a direction orthogonal to the axis in the pin receiving cylinder portion, wherein the external thread portion is screwed into the adjustment nut and the lower part thereof is inserted into the lower pipe portion, A rotation prevention portion that prevents the screw pipe from rotating with respect to the lower column; An upper pipe portion, an upper base plate provided at the upper end of the upper pipe portion, a plurality of upper columns provided at a predetermined distance in the axial direction of the upper pipe portion and having a second pin hole penetrating from one outer circumference to the other outer circumference in a direction orthogonal to the axis, and a lower portion thereof being inserted into the screw pipe; A support pin that continuously penetrates the first pin hole and the second pin hole to fix the screw pipe and the upper column; The thickness of the pin receiving cylinder portion of the screw pipe is configured to be 8 mm or more and 9 mm or less, and the inner diameter of the screw pipe is the same from the lower end to the upper end. The gap between the outer surface of the upper pipe portion and the inner surface of the screw pipe is 3 mm or less. The sizes of the lower base plate and the upper base plate are configured such that a plurality of adjacent reinforcing bars parallel to each other can enter the punching shear range with respect to the slab.

[0014] A preferred example of the temporary construction support of the present invention is At least the upper base plate of the lower base plate and the upper base plate is rectangular, and the length of one side is 170 mm to 200 mm.

[0015] A preferred example of the temporary construction support of the present invention is At least the upper base plate of the lower base plate and the upper base plate is rectangular, and the length of the diagonal is 226 mm to 283 mm.

[0016] According to these temporary construction supports of the present invention, the load-bearing performance of the temporary construction support itself is excellent. In addition, since the dimensions of the upper and lower base plates are devised as described above, the supporting force can reach a wide range of adjacent reinforcing bars and support them, and the occurrence of punching shear failure can be suppressed. For this reason, the supporting force of each temporary construction support can be increased, and the number of installed temporary construction supports can be reduced.

[0017] The installation method of the temporary construction support of the present invention is A method for installing a temporary construction support using the temporary construction support according to the above invention, A positioning step of positioning the upper base plate so that a plurality of adjacent reinforcing bars are parallelly inserted into the range of the punching shear exerted by the temporary construction support on the slab based on the reinforcement drawing, An installation step of installing the temporary construction support based on the position determined in the positioning step, Characterized by comprising.

[0018] According to the method for installing the temporary construction support of the present invention, the same operational effects as those of the invention of the above temporary construction support can be achieved.

[0019] The method for installing the temporary construction support of the present invention is In the installation step, the outer side of the upper base plate is obliquely arranged with respect to a plurality of adjacent reinforcing bars arranged in parallel, and installed so that a plurality of adjacent reinforcing bars are parallelly inserted into the range of the punching shear exerted by the corner of the upper base plate on the slab.

[0020] According to the method for installing the temporary construction support of the present invention, it is possible to cope even when the interval between adjacent reinforcing bars is wide.

Effect of the Invention

[0021] As described above, according to the temporary construction support and the method for installing the temporary construction support of the present invention, by optimizing the size of the lower base plate or the upper base plate, the occurrence of punching shear failure can be suppressed. Further, the number of temporary supports per unit area of the slab can be reduced.

Brief Description of the Drawings

[0022]

Figure 1

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Figure 15

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of the temporary construction support 1 and the installation method of the temporary construction support according to the present invention will be described in detail with reference to the accompanying drawings.

[0024] First, an embodiment of the temporary construction support 1 will be described. The temporary construction support 1 of the present embodiment includes a lower column 10, an adjustment nut 20, a threaded pipe 30, a rotation prevention portion 40, an upper column 50, and support pins 60a and 60b, as shown in FIGS. 1 to 3.

[0025] The lower column 10 is a cylindrical structure that forms the lower side of the temporary construction support 1, and includes a lower pipe portion 11, a lower pipe locking portion 12, and a lower base plate 13. The lower pipe portion 11 is made of a cylindrical member and is hollow inside. The lower pipe locking portion 12 is provided at the upper end of the lower pipe portion 11 and has a flange or flange shape larger than the diameter of the lower pipe portion 11. Note that the position where the lower pipe locking portion 12 is provided only needs to be a position where the adjustment nut 20 can be locked, and the upper end here is intended to include the vicinity of the upper end. Also, regarding the dimensions of the lower pipe portion 11, the outer diameter is 114.3 mm and the wall thickness is 3.5 mm, or the outer diameter is 114 mm and the wall thickness is 4 mm. This is because there are generally products with a 1 / 10 mm unit display (or 1 / 10 mm unit standard, the same below) and products with a 1 mm unit display (or 1 mm unit standard, the same below). Therefore, they are considered substantially the same.

[0026] The lower base plate 13 is provided at the lower end of the lower pipe portion 11, is substantially rectangular in plan view, and has a downward through hole (not shown) at the center of its wide surface. Details of this lower base plate 13 will be described later. Note that the shape of the lower base plate is not limited to the above, and various shapes such as chamfered corners of the lower base plate, polygons or circles other than rectangles in plan view can be adopted (the same applies to the upper base plate 52).

[0027] The adjustment nut 20 is rotatably locked to the lower pipe locking portion 12 provided at the upper end of the lower column 10, and includes a female screw pipe 21, a nut locking portion 23, and a handle 25. The female screw pipe 21 is a cylindrical member provided with a female screw portion 22 (see Fig. 2) on its inner peripheral surface. The nut locking portion 23 is provided on the outer periphery of the female screw pipe 21 and has a laterally oriented recess 24 in front view and rear view. And when this recess 24 is locked to the above-mentioned lower pipe locking portion 12, the adjustment nut 20 is made rotatable. The handle 25 is pivotally supported by the nut locking portion 23 so as to be rotatable in the vertical direction (see arrow a in Fig. 1(A)). And by lifting this handle 25 and turning it horizontally, the adjustment nut 20 is rotated.

[0028] The screw tube 30 is a substantially cylindrical member having a male screw portion 31 on its outer peripheral surface, and is provided with a pin receiving cylinder portion 34 and first pin holes 33a and 33b above the male screw portion 31. The male screw portion 31 is provided on the outer peripheral surface of the screw tube 30, and this male screw portion 31 is screwed into the female screw portion 22 of the adjusting nut 20, and further the lower portion of the screw tube 30 is inserted into the lower tube portion 11 of the lower column 10. Then, by rotating the adjusting nut 20, the screw tube 30 moves in the vertical direction. Note that the upper portion of the screw tube 30 is prevented from going below the adjusting nut 20 by the pin receiving cylinder portion 34. Further, the pin receiving cylinder portion 34 is provided with first pin holes 33a and 33b penetrating from one outer periphery to the other outer periphery in a direction orthogonal to the axis of the screw tube 30. Two sets of these first pin holes 33a and 33b are provided, and are arranged shifted vertically in orthogonal directions. Thereby, the upper first pin hole 33a is arranged at the upper end of the pin receiving cylinder portion 34 and has a semi-circular shape in side view. The dimensions of this screw tube 30 will be described later.

[0029] The rotation prevention portion 40 prevents the screw tube 30 from rotating with respect to the lower column 10. In the present embodiment, as this rotation prevention portion 40, a bolt hole 41 provided in the lower tube portion 11 and penetrating its outer periphery, a fixing nut 42 coaxially with the bolt hole 41 and joined to the outer periphery of the lower tube portion 11 by a method such as welding, a fixing bolt 43 screwed into the fixing nut 42, and a long hole 44 provided along the axial direction on the outer periphery of the screw tube 30 are provided. Here, when the lower portion of the screw tube 30 is inserted into the lower column 10 and the fixing bolt 43 is screwed into the fixing nut 42 with the bolt hole 41 and the long hole 44 aligned, the shaft portion of the fixing bolt 43 is inserted into the long hole 44 of the screw tube 30. Thereby, the screw tube 30 can move in the vertical direction but cannot rotate with respect to the lower tube. Note that although not shown as a rotation prevention portion, in addition to the above, a known configuration such as providing a key protruding from the inner peripheral surface of the lower tube portion 11 and providing a key groove corresponding to the key in the screw tube 30 can be adopted.

[0030] The upper column 50 is a cylindrical member that constitutes the upper side of the temporary construction support 1, and includes an upper pipe portion 51, an upper base plate 52, and second pin holes 55a and 55b. The upper pipe portion 51 is made of a substantially cylindrical member with a hollow interior, and the lower part of the upper pipe portion 51 is inserted into the screw pipe 30 and the lower pipe portion 11. Note that depending on the length of the upper pipe portion 51 and the drawing-out length when using the temporary construction support 1, most parts may be inserted into the screw pipe 30 and the lower pipe portion 11. Here, the dimensions of the upper pipe portion 51 are an outer diameter of 82.6 mm and a wall thickness of 6.0 mm, or an outer diameter of 83 mm and a wall thickness of 6 mm. This is because there are generally products with dimensions indicated in 1 / 10 mm units and products with dimensions indicated in 1 mm units, and they are considered substantially the same (the same applies to the screw pipes described later).

[0031] The upper base plate 52 is provided at the upper end of the upper pipe portion 51. Similar to the lower base plate 13, it is substantially rectangular in plan view and has an upper through-hole (not shown) at the center of its wide surface. The dimensions of this upper base plate 52 will also be described later.

[0032] A plurality of second pin holes 55a and 55b are provided at a predetermined distance in the axial direction of the upper pipe portion 51, and are holes that penetrate from one outer circumference to the other outer circumference in a direction orthogonal to the axis of the upper pipe portion 51. Two sets of these second pin holes 55a and 55b are provided, and are arranged offset in the vertical direction and in orthogonal directions. Also, the second pin holes 55a and 55b are provided so as to correspond to the first pin holes 33a and 33b provided in the screw pipe 30, and when the lower column 10 is drawn out from the screw pipe 30 and the lower column 10 by a predetermined length, the second pin holes 55a and 55b and the first pin holes 33a and 33b are configured to overlap.

[0033] The support pins 60a and 60b continuously penetrate through the first pin holes 33a and 33b provided in the threaded pipe 30 and the second pin holes 55a and 55b provided in the upper pipe portion 51 in a state where they are overlapped, thereby fixing the threaded pipe 30 and the upper column 50. As shown in FIGS. 6(A) and 6(B), the support pins 60a and 60b are provided with a pair of anti - detachment protrusions 61 on the pin side surface at the tip end side. The anti - detachment protrusions 61 are such that the portions protruding from the pin side surface form semi - spherical balls. And in the normal state where the support pins 60a and 60b are inserted into the first pin holes 33a and 33b and the second pin holes 55a and 55b, due to a spring (not shown) inside the support pins 60a and 60b, the anti - detachment protrusions 61 protrude from the pin side surface to prevent detachment from the first pin holes 33a and 33b and the second pin holes 55a and 55b.

[0034] On the other hand, when inserting and removing the support pins 60a and 60b, the anti - detachment protrusions 61 are retracted by an external force to the same position as the pin side surface, enabling the insertion and removal of the support pins 60a and 60b from the first pin holes 33a and 33b and the second pin holes 55a and 55b. This external force includes the case where the anti - detachment protrusions 61 are pushed in by coming into contact with the inner peripheral surfaces of the first pin holes 33a and 33b and the second pin holes 55a and 55b. In this embodiment, pins called ball lock pins are adopted for the support pins 60a and 60b and the anti - detachment protrusions 61. Also, on the base side of the support pins 60a and 60b, support pin holes 62 for fastening an annular member 63 such as a triangular ring or a round ring are provided. This annular member 63 also serves as a stopper to prevent the support pins 60a and 60b from being inserted deeper into the first pin holes 33a and 33b and the second pin holes 55a and 55b than this position.

[0035] Also, two sets of support pins 60a and 60b are provided, and the first pin holes 33a and 33b and the second pin holes 55a and 55b are arranged such that the two support pins 60a and 60b are inserted crossing each other.

[0036] Next, the configuration specific to the temporary construction support 1 of the present embodiment mainly in the screw pipe 30 will be described. As shown in FIGS. 4(A) to (C), in the temporary construction support 1 of the present embodiment, it is preferable that the wall thicknesses t1 and t2 of the screw pipe 30 are thicker than the wall thickness of 6 mm or more of the upper pipe portion 51. Specifically, for the pipe material that is the material of the screw pipe 30, a product with an outer diameter of 101.6 mm and a wall thickness of 8.0 mm in a product indicated in 1 / 10 mm units and a product with an outer diameter of 102 mm and a wall thickness of 8 mm in a product indicated in 1 mm units are used. And, the pin receiving cylinder portion 34 is processed only with the first pin holes 33a and 33b, and since screw processing is not required, the wall thickness t1 here remains 8 mm as it is. Further, the wall thickness t2 of the male screw portion 31 inevitably becomes thinner due to cutting the male screw portion 31, and in the present embodiment, it is 6 mm which is slightly thinner than the pin receiving cylinder portion 34. This is substantially the same as the wall thickness of 6 mm of the upper pipe portion 51. As a result, the width w1 at which the first pin holes 33a and 33b come into contact with the support pins 60a and 60b becomes wider, and also in the male screw portion 31, the wall thickness t2 becomes thicker and the strength is improved. When thickening the wall thickness of the pipe material, it is generally thickened toward the inner diameter direction. For this reason, the outer diameter of the screw pipe 30 does not change and only the inner diameter changes. Thereby, the gap s between the inner side of the screw pipe 30 and the outer side of the upper pipe portion 51 shown in FIG. 7 becomes narrower. Further, since the outer diameter of the screw pipe 30 does not change, the lower column 10 and the adjustment nut 20 of the generally used temporary construction support can be used as they are.

[0037] Next, a conventional screw tube 530 shown in FIGS. 5(A) to 5(C) will be described. In the conventional product, a pipe material that is the material of the screw tube 530 has a thinner wall thickness compared to this embodiment. For this reason, the wall thickness t5 of the pin receiving cylinder portion 534 is thin, and the width w3 where the first pin holes 533a and 533b contact the support pins 60a and 60b is narrow. Also, the wall thickness t6 of the male screw portion 531 is thinner than the wall thickness of the upper pipe portion 51. Specifically, in a product indicated in 1 / 10 mm units, the outer diameter of the screw tube 530 (pin receiving cylinder portion 534) is 101.6 mm, the wall thickness t5 of the pin receiving cylinder portion 534 is 7.0 mm, and the wall thickness t6 of the male screw portion 531 is thinned by cutting to 5.0 mm (by the applicant's actual measurement). Also, in a product indicated in 1 mm units that is substantially the same as the above product indicated in 1 / 10 mm units, the outer diameter of the screw tube 530 (pin receiving cylinder portion 534) is 102 mm, the wall thickness t5 of the pin receiving cylinder portion 534 is 7 mm, and the wall thickness t6 of the male screw portion 531 is thinned by cutting to 5 mm. As a result, not only do the support pins 60a and 60b and the male screw portion 531 easily deform when a load is applied, but also the gap s (see FIG. 7) between the inside of the screw tube 530 and the outside of the upper pipe portion 51 becomes wide, and the screw tube 530 or the upper pipe portion 51 is likely to break.

[0038] The wall thicknesses of the screw tubes 30 and 530 described above are summarized with reference to FIG. 8(A). As shown in FIG. 8(A), in the screw tube 30 of this embodiment, the wall thickness t1 of the pin receiving cylinder portion 34 is 8 mm, which is 2 mm thicker than the wall thickness of 6 mm of the upper pipe portion 51, and the wall thickness t2 of the male screw portion 31 is 6 mm, which is equivalent. In the conventional screw tube 530, the wall thickness t5 of the pin receiving cylinder portion 534 is 7 mm, which is 1 mm thicker than the wall thickness of the upper pipe portion 51, and the wall thickness t6 of the male screw portion 531 is 5 mm, which is 1 mm thinner.

[0039] Next, referring to FIG. 8(B), the results of the strength test of the temporary construction support will be described. In CH32B (this embodiment) shown in this table, the threaded pipe 30 is used, and in CH32 (conventional product), the threaded pipe 530 is used. Also, the lower column 10, the adjustment nut 20, and the upper column 50 are both using equivalent products. As a result, in terms of the maximum load at which the temporary construction support buckles and deforms, the conventional product is 294 kN, while the temporary construction support 1 according to this embodiment is 432 kN, showing a significant improvement. Also, the allowable load that can be normally used, which is half of the maximum load, is 147 kN for the conventional product and 216 kN for the temporary construction support 1 according to this embodiment.

[0040] As factors for this significant improvement in strength, it is a matter of course that the support pins 60a and 60b are less likely to bend. However, it is presumed that the thicknesses t1 and t2 of the threaded pipe 30 have increased, improving the strength of the threaded pipe 30 itself, and the gap s (see FIG. 7) between the threaded pipe 30 and the upper pipe portion 51 has become narrower. This is because there are gaps between the lower pipe portion 11, the threaded pipe 30, and the upper pipe portion 51. During the strength test, the area near the threaded pipe 30 becomes like a joint and deforms into a U-shape. It is obvious that the greater the degree of bending into this U-shape, the weaker the strength of the temporary construction support. Eventually, the area near the threaded pipe 30 deforms and the temporary construction support buckles. In the temporary construction support 1 of this embodiment, by increasing the thicknesses t1 and t2 of the threaded pipe, the degree of bending into a U-shape is suppressed, and furthermore, the threaded pipe 30 itself is also less likely to bend, resulting in improved strength.

[0041] Next, with reference to Fig. 9(A), the relationship between the wall thickness t1 of the threaded pipe 30 (pin receiving cylinder portion 34) and the gap s (see Fig. 7) between the inner surface of the threaded pipe 30 and the upper pipe portion 51 will be described. Fig. 9(A) shows the dimensions of the upper pipe portion 51, the threaded pipe 30 (pin receiving cylinder portion 34), and the lower pipe portion 11 for a conventional product with a 1 / 10 mm unit display, a conventional product with a 1 mm unit display, and the temporary construction support 1 according to the present embodiment (1 mm unit display). The inner diameter of the threaded pipe shown in Fig. 9(A) can be easily obtained by "the outer diameter of the threaded pipe - the wall thickness of the threaded pipe × 2". And when calculating the gap s between the inner surface of the threaded pipe 30 and the upper pipe portion 51, it is as follows. ·Calculation formula Inner diameter of the threaded pipe - Outer diameter of the upper pipe portion = Gap s ·Conventional product with a 1 / 10 mm unit display 87.6 mm - 82.6 mm = 5 mm ·Conventional product with a 1 mm unit display 88 mm - 83 mm = 5 mm ·Temporary construction support 1 according to the present embodiment 86 mm - 83 mm = 3 mm Thus, while the gap s of the conventional product is 5 mm, the gap s of the temporary construction support 1 according to the present embodiment is 3 mm. Accordingly, the temporary construction support 1 is suppressed from bending in a V shape and the strength is improved.

[0042] Next, with reference to FIG. 9(B), the optimal range of the wall thickness of the screw tube 30 (pin receiving cylinder portion 34) will be described. As described above, when the wall thickness of the screw tube 30 (pin receiving cylinder portion 34) is 8 mm, the gap s between the inner surface of the screw tube 30 and the outer surface of the upper tube portion 51 is 3 mm. Also, in principle, the wall thickness of the screw tube 30 (pin receiving cylinder portion 34) can be increased up to 9.5 mm at which the gap s becomes 0 mm. However, it is not realistic to set the gap s to 0 mm due to the possibility that foreign matters such as gravel and dust may enter the gap s between the inner surface of the screw tube 30 and the outer surface of the upper tube portion 51, the possibility that scratches or the like may occur on the inner surface of the screw tube 30 and the outer surface of the upper tube portion 51 resulting in unevenness, and tolerances during the manufacture of the screw tube 30 and the like. For this reason, it is preferable to set the gap s to be 3 mm or less and 1 mm or more. In this case, the wall thickness t1 of the screw tube 30 (pin receiving cylinder portion 34) becomes 8 mm or more and 9 mm or less, and the wall thickness t2 of the male screw portion 31 becomes 6 mm or more and 7 mm or less because it is reduced by cutting. Also, compared with the wall thickness of 6 mm of the upper tube portion 51, the wall thickness of the screw tube 30 (pin receiving cylinder portion 34) is thickened in the range of 2 mm or more and 3 mm or less, and the wall thickness of the male screw portion 31 is thickened in the range of 0 mm or more and 1 mm or less.

[0043] Furthermore, by limiting the above-mentioned gap s to 3 mm or less and 2 mm or more, even if foreign matters such as gravel and dust enter the gap s, the movement of the screw tube 30 and the upper tube portion 51 is less likely to be hindered. In this case, the wall thickness t1 of the screw tube 30 (pin receiving cylinder portion 34) becomes 8 mm or more and 8.5 mm or less, and the wall thickness t2 of the male screw portion 31 becomes 6 mm or more and 6.5 mm or less. Also, compared with the wall thickness of 6 mm of the upper tube portion 51, the wall thickness of the screw tube 30 (pin receiving cylinder portion 34) is thickened in the range of 2 mm or more and 2.5 mm or less, and the wall thickness of the male screw portion 31 is thickened in the range of 0 mm or more and 0.5 mm or less.

[0044] On the other hand, by limiting the above-mentioned gap s to less than 2 mm and not less than 1 mm, the gap s becomes narrower and the wall thickness of the screw tube 30 also becomes thicker, and further improvement in the strength of the temporary construction support 1 can be expected. In this case, the wall thickness t1 of the screw tube 30 (pin receiving cylinder portion 34) exceeds 8.5 mm and is 9 mm or less, and the wall thickness t2 of the male screw portion 31 exceeds 6.5 mm and is 7 mm or less. Also, when compared with the wall thickness of 6 mm of the upper tube portion 51, the wall thickness of the screw tube 30 (pin receiving cylinder portion 34) is thickened in the range exceeding 2.5 mm and not exceeding 3 mm, and the wall thickness of the male screw portion 31 is thickened in the range exceeding 0.5 mm and not exceeding 1 mm.

[0045] As described above, these gaps s depend on the wall thickness (inner diameter) of the screw tube 30 and the outer diameter of the upper tube portion 51. For this reason, it is considered that there are fluctuations in units of one-tenth of a millimeter due to tolerances during the manufacture of the pipe material and the like.

[0046] Next, with reference to FIGS. 10 to 14, the lower base plate 13 and the upper base plate 52 of the temporary construction support 1 of the present embodiment will be described. As already described, punching shear is likely to occur when an upward force is applied from below by the upper base plate 52 at a location where the upper end bars (not shown) such as the central portion of the slab 72 are omitted. For this reason, the upper base plate 52 will mainly be described here, but there is no particular problem in making the lower base plate 13 have the same configuration as the upper base plate 52. Refer to FIG. 15 for the punching shear of the lower base plate 13. In FIGS. 10 and later, reinforcing bars with a diameter of 9 mm are shown.

[0047] First, referring to FIG. 10, a punching shear by the upper base plate 52z using a conventional temporary construction support will be described. As already mentioned, originally, the center distance between adjacent main reinforcing bars 70a, 70b, 70c should be 200 mm or less. However, from the 1950s to the 1960s, in order to reduce the amount of reinforcing bars used, in buildings with relatively light loading such as residences, if there were no problems in structural calculations, the center distance between adjacent main reinforcing bars 70a, 70b, 70c was increased. The length of this center distance is, for example, 210 mm, 220 mm, etc. Also, the cover thickness of the reinforcing bars 70a, 70b, 70c was 20 mm depending on the building. In addition, in old buildings, the thickness of the slab 72 is often relatively thin at 120 mm, which is also one of the factors that makes punching shear failure likely to occur.

[0048] Therefore, when the center distance between adjacent main reinforcing bars 70b, 70c becomes 210 mm or 220 mm, the main reinforcing bars 70b, 70c may deviate from the range of the punching shear p10 exerted by the upper base plate 52z. Also, even if the center distance between adjacent main reinforcing bars 70a is 200 mm, there is a possibility that a part of the main reinforcing bar 70a may deviate from the range of the punching shear p10 exerted by the upper base plate 52z. In such a state, when a heavy machine passes over the slab 72, the possibility of punching shear failure increases, which is dangerous.

[0049] Therefore, in the temporary construction support 1 of the present embodiment, as shown in FIG. 11, the upper base plates 52a, 52b, 52c, 52d are made substantially rectangular (square) in plan view, and the length of one side is set to 170 mm to 200 mm. These upper base plates 52a, 52b, 52c, 52d may or may not chamfer the corner portions 56. Here, a C10 chamfer is made in the case of chamfering the corner portions 56. In FIGS. 11 and 13, the description of the upper through holes provided at the center of the wide surface of the upper base plates 52a, 52b, 52c, 52d is omitted. FIG. 13 is a perspective view of the main reinforcing bars 70 and the distribution bars 71 in the slab as seen from below looking up at the upper base plate 52a (52b, 52c, 52d).

[0050] Next, referring to FIG. 12, the punching shears p1, p2, p3, and p4 when the upper base plates 52a, 52b, 52c, and 52d shown in FIG. 11 are arranged such that their outer sides 57 are in the direction along the main reinforcement 70 (the state represented by the broken line in FIG. 13) will be described. The overlapping thickness here is also set to 20 mm. As shown in the figure, when the center distance between the main reinforcements 70a is 200 mm, for the upper base plate 52a with a side length of 170 mm, a plurality of adjacent parallel reinforcing bars 70a will enter the range of the punching shear p1. Also, if a plurality of adjacent parallel reinforcing bars 70a enter the range of the punching shear p1, even if the installation position of the temporary construction support 1 is displaced for some reason, at least one reinforcing bar 70a will enter the range of the punching shear p1 of the upper base plate 52a (the same applies in the following embodiments).

[0051] Also, for the upper base plate 52b with a side length of 180 mm, even if the center distance between the main reinforcements 70b is 210 mm, a plurality of adjacent parallel reinforcing bars 70b can be made to enter the range of the punching shear p2. Similarly, for the upper base plate 52c with a side length of 190 mm, even if the center distance between the main reinforcements 70c is 220 mm, a plurality of adjacent parallel reinforcing bars 70c can be made to enter the range of the punching shear p3. Further, for the upper base plate 52d with a side length of 200 mm, even if the center distance between the main reinforcements 70c is 220 mm, a plurality of adjacent parallel reinforcing bars 70c can be made to enter the range of the punching shear p4 with a margin. That is, the side length of the upper base plates 52a, 52b, 52c, and 52d is preferably 170 mm or more and 180 mm or less, more preferably more than 180 mm and 190 mm or less, and even more preferably more than 190 mm and 200 mm or less. Also, by the same reasoning, it can be said that more than 200 mm and 210 mm or less is even more preferable. However, if the dimensions of the upper base plates 52a, 52b, 52c, and 52d are made too large, it will cause problems in transportation and storage, so it is preferable to make them 210 mm or less.

[0052] Returning to FIG. 11, the diagonal dimensions of the upper base plates 52a, 52b, 52c, and 52d will be described. In the case of the upper base plate 52a with a side length of 170 mm, the diagonal length is 226 mm (rounded off to the nearest whole number after the decimal point, the same applies hereinafter) when chamfered with a C10 chamfer, and 240 mm when not chamfered. Further, in the case of the upper base plate 52b with a side length of 180 mm, the diagonal length is 240 mm when chamfered with a C10 chamfer, and 255 mm when not chamfered. Additionally, in the case of the upper base plate 52c with a side length of 190 mm, the diagonal length is 255 mm when chamfered with a C10 chamfer, and 269 mm when not chamfered. Moreover, in the case of the upper base plate 52d with a side length of 200 mm, the diagonal length is 269 mm when chamfered with a C10 chamfer, and 283 mm when not chamfered.

[0053] The situation when the outer sides 57 of these upper base plates 52a, 52b, 52c, and 52d are arranged diagonally with respect to a plurality of adjacent parallel reinforcing bars 70 and 71 as shown by the solid lines in FIG. 13 will be described. This means that the diagonals of the upper base plates 52a, 52b, 52c, and 52d are arranged in a direction approximately orthogonal to a plurality of adjacent parallel reinforcing bars 70 and 71. When the upper base plates 52a, 52b, 52c, and 52d are installed diagonally in this way, the punching shears p5, p6, p7, p8, and p9 will be approximately as shown in FIG. 14. FIG. 14 is a diagram for explaining the punching shears p5, p6, p7, p8, and p9 with respect to the distribution bars 71a, 71b, 71c, 71d, 71e, and 71f placed on the main reinforcing bars 70 arranged in the left - right direction of the figure.

[0054] As shown in FIG. 14, when using the upper base plate 52a (see FIG. 11) with a diagonal dimension of 226 mm, it can be placed within the range of the punching shear p5 up to a center distance of 270 mm between adjacent parallel reinforcing bars 71c. Also, when using the upper base plates 52a and 52b with a diagonal dimension of 240 mm, it can be placed within the range of the punching shear p6 up to a center distance of 290 mm between adjacent parallel reinforcing bars 71e. Here, the reason for selecting multiple upper base plates with the same diagonal dimension is that there are those with chamfers at the corners 56 and those without chamfers, and the diagonal dimensions are different for each (the same applies hereinafter). Further, when using the upper base plates 52b and 52c with a diagonal dimension of 255 mm, it can be placed within the range of the punching shear p7 up to a center distance of 300 mm between adjacent parallel reinforcing bars 71f. Furthermore, when using the upper base plates 52c and 52d with diagonal dimensions of 269 mm and 283 mm, it can be placed within the ranges of the punching shears p8 and p9 with a margin up to a center distance of 300 mm between adjacent parallel reinforcing bars 71f. That is, it is preferable to use the upper base plate with a diagonal length of 226 mm or more and 240 mm or less, more preferably 240 mm or more and 255 mm or less, and even more preferably 255 mm or more and 283 mm or less.

[0055] The center distance of 300 mm between adjacent reinforcing bars 71f is the dimension that covers the span of the load-bearing bars among the reinforcing bars in the slab 72. The load-bearing bars are specified to have a center distance between reinforcing bars of 300 mm or less. In recent buildings, they may be arranged with the same 200 mm as the main bars, but in older buildings, they are often arranged with dimensions of 250 - 300 mm. Looking at it, by arranging the upper base plates 52a, 52b, 52c, 52d obliquely as shown by the solid lines in Fig. 13, a total of four reinforcing bars, namely two adjacent main bars 70 and two adjacent load-bearing bars 71 that intersect with them, can be placed within the range of the punching shear p5, p6, p7, p8, p9 of the upper base plates 52a, 52b, 52c, 52d. Also, even if the positions of the upper base plates 52a, 52b, 52c, 52d are displaced, a plurality of reinforcing bars 70, 71 can be placed within the range of the punching shear p5, p6, p7, p8, p9 with a high probability, and at least one reinforcing bar can be placed within the range of the punching shear p5, p6, p7, p8, p9 no matter how much the position is displaced.

[0056] Next, an embodiment of the installation method of the temporary construction support using the above-described temporary construction support 1 will be described. The installation method of the temporary construction support of this embodiment includes a positioning step and an installation step.

[0057] The positioning step is a step of determining the positions where the upper base plates 52a, 52b, 52c, 52d and the lower base plate 13 of the temporary construction support are to be arranged based on the reinforcement drawing of the building to be demolished. At this time, it is preferable to arrange a plurality of adjacent reinforcing bars 70a, 70b, 70c in parallel within the range of the punching shear of the upper base plates 52a, 52b, 52c, 52d with respect to the slab 72. These plurality of adjacent reinforcing bars 70a, 70b, 70c that are parallel are preferably the main bars 70, and furthermore, at least one, preferably two, of the load-bearing bars 71 that intersect with the main bars 70 are placed within the range of the punching shear of the upper base plates 52a, 52b, 52c, 52d. By positioning the upper base plates 52a, 52b, 52c, 52d in this way, three, or four reinforcing bars if conditions are good, can be placed within the range of the punching shear.

[0058] Next, as an installation process, a temporary construction support is installed at the position determined in the positioning process. At this time, as shown by the broken lines in FIG. 13, the upper base plates 52a, 52b, 52c, 52d may be arranged, but as shown by the solid lines in FIG. 13, it is preferable to arrange the outer sides 57 of the upper base plates 52a, 52b, 52c, 52d obliquely with respect to a plurality of parallel and adjacent reinforcing bars 70, 71. By arranging in this way, four main reinforcing bars 70 and shear reinforcement bars 71 that are parallel, adjacent, and intersecting can be inserted in a "well" shape within the range of punching shear p5, p6, p7, p8, p9 exerted by the corner portions 56 of the upper base plates 52a, 52b, 52c, 52d on the slab 72. By installing in this way, a plurality of reinforcing bars can be more surely inserted within the range of the punching shear p5, p6, p7, p8, p9 of the upper base plates 52a, 52b, 52c, 52d.

[0059] Also, as already described, in the temporary construction support, the allowable load for normal use is 147 kilonewtons for the conventional product, while the temporary construction support 1 according to the present embodiment is 216 kilonewtons. From this value, 147÷216 = approximately 0.68, and the number of installed temporary construction supports 1 can be reduced to approximately 68% of the conventional product in terms of calculation. This is because even if the upper base plate of the conventional temporary construction support is made to have an appropriate dimension, although the effect of making punching shear failure less likely to occur can be obtained, it is difficult to reduce the number of installed temporary construction supports because the allowable load of the temporary construction support itself is small. On the other hand, in the temporary construction support 1 of the present invention, by making the upper base plates 52a, 52b, 52c, 52d have appropriate dimensions, punching shear failure is less likely to occur, and accordingly, the load borne by each temporary construction support 1 can be increased.

[0060] As described above, according to the temporary construction support and the installation method of the temporary construction support of the present embodiment, by appropriately setting the size of the upper base plate, a plurality of reinforcing bars can be placed within the range of the punching shear exerted by the upper base plate on the slab. Even if the position of the upper base plate is displaced, at least one reinforcing bar can be placed. Further, by arranging the outer side of the upper base plate obliquely with respect to the reinforcing bar, the reinforcing bar can be more surely placed within the range of the punching shear. As a result, punching shear failure is less likely to occur, and the safety during demolition work can be improved. Even if punching shear failure occurs, since the supporting force of the upper base plate acts on the reinforcing bar, the progress of the failure becomes gentle, and there is a high possibility that time for evacuation can be created.

[0061] Also, by increasing the wall thickness of the screw pipe, a significant improvement in the strength of the temporary construction support can be achieved. Thereby, an increase in weight can be suppressed, and a reduction in manufacturing cost can also be achieved.

[0062] Furthermore, in combination with the fact that punching shear failure is less likely to occur, by improving the strength of the temporary construction support, the number of installations per unit area can be reduced. Thereby, improvement in work efficiency and reduction in work cost at the construction site can be achieved.

[0063] Note that the above-described temporary construction support and the installation method of the temporary construction support are examples of the present invention, and the configuration can be appropriately changed without departing from the gist of the invention.

Explanation of Reference Numerals

[0064] 1 ··· Temporary construction support, 10 ··· Lower column, 11 ··· Lower pipe part, 12 ··· Lower pipe locking part, 13 ··· Lower base plate, 20 ··· Adjusting nut, 21 ··· Female screw pipe, 22 ··· Female screw part, 23 ··· Nut locking part, 24 ··· Concave part, 25 ··· Handle, 30,530 ·· Screw tube, 31,531 ·· Male screw part, 33a, 33b, 533a, 533b ·· First pin hole, 34, 534 ·· Pin receiving cylinder part, 40 ·· Anti-rotation part, 41 ·· Bolt hole, 42 ·· Fixing nut, 43 ·· Fixing bolt, 44 ·· Long hole, 50 ·· Upper column, 51 ·· Upper tube part, 52a, 52b, 52c, 52d, 52z ·· Upper base plate, 55a, 55b ·· Second pin hole, 56 ·· Corner part, 57 ·· Outer side, 60a, 60b ·· Support pin, 61 ·· Anti-drop protrusion part, 62 ·· Support pin hole, 63 ·· Annular member, 70, 70a, 70b, 70c ·· Main reinforcement (reinforcing bar), 71, 71a, 71b, 71c, 71d, 71e, 71f ·· Force-distributing reinforcement (reinforcing bar), 72 ·· Slab, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10, p11 ·· Punching shear,

Claims

1. A lower column including a lower pipe portion and a lower base plate provided at a lower end of the lower pipe portion; An upper column including an upper tube portion and an upper base plate provided at an upper end of the upper tube portion, A temporary construction support that is erected between upper and lower slabs of a building to be demolished, in which the upper pipe portion is inserted into the lower pipe portion and the distance between the lower base plate and the upper base plate is adjustable, A temporary construction support characterized in that the size of the lower base plate and the upper base plate is configured so that multiple adjacent parallel reinforcing bars can fit within the range of the punching shear against the slab.

2. 2. A temporary construction support as claimed in claim 1, wherein at least the upper base plate of the lower base plate and the upper base plate is rectangular with a side length of 170 mm to 200 mm.

3. 2. A temporary construction support according to claim 1, wherein at least the upper base plate of the lower base plate and the upper base plate is rectangular and has a diagonal length of 226 mm to 283 mm.

4. A temporary construction support erected between the upper and lower slabs of a building to be demolished, a lower column including a lower pipe portion, a lower base plate provided at a lower end of the lower pipe portion, and a lower pipe engaging portion provided at an upper end of the lower pipe portion; an adjustment nut rotatably engaged with the lower pipe engaging portion; a threaded pipe including a male threaded portion provided on an outer circumferential surface, a pin receiving cylinder portion provided above the male threaded portion, and a first pin hole penetrating from one outer periphery to the other outer periphery of the pin receiving cylinder portion in a direction perpendicular to an axis, the male threaded portion being screwed into the adjustment nut and a lower portion of the male threaded portion being inserted into the lower pipe portion; A rotation prevention portion that prevents the threaded pipe from rotating relative to the lower column; an upper tube portion; an upper base plate provided at the upper end of the upper tube portion; and an upper column having a second pin hole provided at a predetermined distance in the axial direction of the upper tube portion and penetrating from one outer periphery to the other outer periphery in a direction perpendicular to the axis, the lower part of which is inserted into the threaded tube; A support pin that passes through the first pin hole and the second pin hole continuously to fix the threaded pipe and the upper column, The thickness of the pin receiving cylinder portion of the threaded pipe is 8 mm or more and 9 mm or less, and the inner diameter of the threaded pipe is the same from the lower end to the upper end, The gap between the outer surface of the upper tube portion and the inner surface of the threaded tube is 3 mm or less, A temporary construction support characterized in that the size of the lower base plate and the upper base plate is configured so that multiple adjacent parallel reinforcing bars can fit within the range of the punching shear against the slab.

5. 5. A temporary construction support according to claim 4, wherein at least the upper base plate of the lower base plate and the upper base plate is rectangular with a side length of 170 mm to 200 mm.

6. 5. A temporary construction support according to claim 4, wherein at least the upper base plate of the lower base plate and the upper base plate is rectangular and has a diagonal length of 226 mm to 283 mm.

7. A method for installing a temporary work support using the temporary work support according to any one of claims 1 to 6, comprising the steps of: A positioning step of positioning the upper base plate so that a plurality of parallel adjacent reinforcing bars are included in the range of punching shear applied by the temporary work support to the slab based on a reinforcing bar arrangement drawing; an installation step of installing the temporary work support based on the position determined in the positioning step; A method for installing supports for temporary construction, comprising:

8. A method for installing supports for temporary construction work as described in claim 7, wherein, in the installation process, the outer edge of the upper base plate is positioned at an angle to multiple adjacent parallel reinforcing bars, and the multiple adjacent parallel reinforcing bars are installed so that they are within the range of punching shear exerted by the corners of the upper base plate on the slab.

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