JP2023075097A - Construction method of structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method of a structure capable of maintaining a smooth surface of the structure.

SOLUTION: A construction method of a structure of this invention includes: disposing a curved surface frame 50 having an outer curved surface 50s running along a shape of an inner curved surface 12s so that the inner curved 12s of a structure 10 faces in a downward direction different from an upward direction in which a floating matter (an air bubble or bleeding water) of concrete emerges; installing concrete using the curved surface frame 50 to form a precast member; and thereby forming a lower member 12. The construction method further includes: disposing the lower member 12 to assume a predetermined position in which the inner curved surface 12s of the lower member 12 faces in the upward direction; and disposing an upper member 11 having an inner curved surface 11s on the lower member 12 to constitute the structure 10.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a method of constructing structures with smooth surfaces.

A facility that conducts wind tunnel experiments uses a cylindrical frame with a curved surface called a windpipe. A windpipe has a complicated shape because its cross section continuously changes from a circular shape to a rectangular shape, and requires dimensional accuracy in the cross section.
Steel materials are often used for the construction of this wind pipe. In this case, the cost is increased, and the welded portion is distorted by heat, making it difficult to form a highly accurate curved surface.

On the other hand, when the wind pipe is constructed of concrete, it is difficult to ensure the accuracy of the curved surface due to the unevenness of the surface caused by the generation of loose substances (for example, air bubbles and bleeding water) in the concrete. Therefore, techniques for reducing unevenness on the surface of concrete have been studied (see Patent Document 1, for example). In the precast concrete described in this document, concrete is placed in a space formed by a formwork with an opening at the top, and the opening of the space is closed with a lid. A filter sheet is provided on the rear surface of the lid, and an opening for partially opening the filter sheet is provided in a part of the lid. Air bubbles mixed into the concrete during concrete placement are released to the outside through the filter sheet and the opening, so that the surface of the concrete can be made smooth.

JP-A-2004-197361

By the way, a large pressure is applied to the inner surface of the wind pipe through which high-speed wind flows. For this reason, in the technique described in the literature, a pressure difference occurs between the filter sheet and the concrete, and the surface portion above the filter sheet tends to peel off. Also, even if the unevenness of the part where the surface part has peeled off is smoothed with a plasterer, the repaired part may also peel off, making it difficult to maintain a smooth surface.

A method of constructing a structure for solving the above-mentioned problems is a method of constructing a structure including a smooth surface of a precast member having a shape extending in the axial direction and made of concrete at a predetermined position. A formwork having a forming surface corresponding to the planar shape of the smooth surface is arranged so that the smooth surface of the precast member is arranged downward, opposite to the upward direction in which loose matter in the concrete of a plurality of partition plates arranged at positions corresponding to the range of concrete to be cast in one time are erected in the formwork at intervals in the axial direction; The structure is constructed by forming split precast members and arranging the precast members obtained by uniting the split precast members such that the smooth surface is at the predetermined position.

According to the present invention, structures having smooth surfaces can be formed.

FIG. 4 is a conceptual diagram of a construction method of a structure according to the embodiment; 1A and 1B are cross-sectional views illustrating the configuration of a wind tunnel apparatus according to an embodiment, in which (a) shows a circular cross section and (b) shows a rounded cross section; 1 is a perspective view of a precast member formed in an example; FIG. Explanatory drawing of the formwork used in order to form a precast member in an Example. FIG. 4A is a side view, and FIG. 4B is a perspective view for explaining the placement of the formwork for forming the precast member in the example. FIG. 4 is an explanatory diagram of a method of constructing a wind tunnel apparatus in an embodiment, in which (a) is the state where columns and floors are formed, (b) is the state where the lower precast member is arranged, and (c) is the side wall formwork. , and (d) shows the state in which the sidewalls are formed. The perspective view of the principal part in the state where even the side wall part was formed in an Example. It is explanatory drawing of the method to construct the wind tunnel apparatus in an Example, Comprising: (a) shows the state where the formwork which forms an upper member is arrange|positioned, (b) shows the state where the upper member was formed. FIG. 10 is an explanatory view explaining formation of a precast member in a modified example, wherein (a) is a top view, (b) is a cross-sectional view, (c) is a top view, and (d) is a cross-sectional view. FIG. 11 is an explanatory diagram of a structure having an uneven outer curved surface in a modified example;

An embodiment embodying a structure construction method will be described below with reference to FIGS. 1 to 8. FIG.
First, with reference to FIG. 1, the outline of the construction method of the structure will be described.
In this embodiment, structure 10 is constructed using upper member 11 and lower member 12 . The upper member 11 has an inner curved surface 11s as a smooth surface, and the lower member 12 has an inner curved surface 12s as a second smooth surface. The lower member 12 is formed so that the inner curved surface 12s faces downward (second direction) and is installed upside down. Specifically, the lower member 12 is formed by placing concrete on the curved formwork 50 with the outer curved surface 50s, which is the forming surface, facing upward. Then, the lower member 12 of the structure is installed so that the inner curved surface 12s, which was downward at the time of formation, faces upward (first direction) at a predetermined position, and the upper member is placed thereon with the inner curved surface 11s facing downward. Build 11.

Next, with reference to FIGS. 2 to 8, an embodiment embodying a method of constructing a structure will be described in detail. In the examples, hatching is omitted for reinforced concrete and curved formwork.
As shown in FIG. 2, a structure 15 is formed to form a space for wind tunnel experiments. This structure 15 is installed on a floor 21 formed on a plurality of pillars 20 . This structure 15 is an elongated object having an inner curved surface 15s that forms a space whose cross section continuously changes from a circular shape to a rounded square shape. The rounded quadrangular shape is a quadrangular (square) shape with arcuate corners.

2(a) and 2(b) show cross sections at one end and central portion of the structure 15, respectively. As shown in FIG. 2(a), the inner curved surface 15s at one end of the structure 15 has a circular cross section as a whole. As shown in FIG. 2(b), the inner curved surface 15s in the central portion of the structure 15 has a rounded square cross section as a whole. The structural body 15 of the present embodiment is provided with four members (26, 27, 31, 32) which are divided vertically and horizontally into four members (26, 27, 31, 32) extending in the axial direction and having arcuate cross sections. The upper members 26, 27 and the lower members 31, 32 of the structure 15 have inner curved surfaces 26s, 27s, 31s, 32s of the same curved surface shape, respectively. A pair (two) of the lower members 31 and 32 arranged on the lower side among them are formed of precast members.

FIG. 3 is a perspective view of the lower member 31 placed on the curved mold 51. As shown in FIG. The lower member 31 has a length having an inner curved surface 31s that has a 1/4 arc on one end (front in the figure) and an arc of rounded square corners toward the other end (rear). It is a measure. 31 s of this inner curved surface becomes small as the curvature radius of an arc goes back. In this embodiment, the inner curved surface 31s is formed with precision (surface roughness equal to or less than a reference value) that does not affect wind tunnel experiments. The lower member 31 is composed of a plurality of precast members 31a, 31b, 31c and 31d.

FIG. 4 shows curved forms 51 and 52 . Curved forms 51,52 are used to form upper members 26,27 and lower members 31,32. The outer curved surfaces 51s, 52s as forming surfaces of the curved forms 51, 52 have shapes along the shapes of the inner curved surfaces 26s, 27s, 31s, 32s as smooth surfaces of the upper members 26, 27 and the lower members 31, 32. have. Specifically, the outer shape of the curved molds 51 and 52 is a shape that continuously changes such that one side is a 1/4 arc shape and the other side is an L shape with rounded corners. Therefore, the cross-sectional shape of the curved molds 51 and 52 is configured to have a planar shape with the same curvature as the inner curved surfaces 26s, 27s, 31s and 32s in the cross section. Further, the inner portions 51a, 52a of the curved forms 51, 52 are trapezoidal. As a result, it is possible to mount a frame and attach shoring, which will be described later.

<Method of constructing a structure>
Next, a method of constructing a structure in the embodiment will be described with reference to FIGS. 5 to 8. FIG.
First, the lower members 31, 32 are formed prior to on-site construction. Since the lower members 31 and 32 are formed by the same method, the method for forming the lower member 31 will be described here.

As shown in FIGS. 5(a) and 5(b), a frame 60 configured by combining a plurality of H-shaped steels 61 is installed. In this case, the H-shaped steel 61 is assembled so that the upper part of the frame 60 has a trapezoidal shape.

Next, the curved formwork 51 is placed on the mount 60 . In this case, the curved formwork 51 is installed so that the trapezoidal inner part 51 a of the curved formwork 51 is fitted to the upper part of the mount 60 .
The formwork (55, 56, 57, 58) is placed in connection with the curved formwork 51. As shown in FIG. In this case, an opening P1 is provided at the top. Further, a partition plate 65 is erected on the curved formwork 51 at a position corresponding to the size of each precast member (31a to 31d). The partition plate 65 is arranged at a position according to the setting of the weight and length of each precast member (31a to 31d), and specifies the range (area) of concrete to be placed at one time. In addition, a reinforcing bar (not shown) is arranged in the area surrounded by the curved formwork 51, the formwork (55, 56, 57, 58) and the partition plate 65, and one end of the reinforcing bar is connected to the lower member 31 project from one side of the

Next, concrete is poured from the opening P1 into each range partitioned by the partition plate 65, and compacted by a vibrator. In this case, the concrete may be poured from the end and compacted in order, or not in order. As the concrete hardens, concrete looses (eg, air bubbles, bleeding water, etc.) float upward.
Here, as shown in FIG. 3, the lower member 31 is formed with the inner curved surface 31s facing downward. The chamfered portion C1 at the corner of the lower member 31 is formed by the horizontal surface of ready-mixed concrete poured into the mold.

After that, the molds (55, 56, 57, 58) are removed, and the partition plate 65, which is the boundary between the precast members (31a-31d), is removed. Note that the partition plate 65 may be removed before all the precast members (31a to 31d) are formed, when concrete placement in the partitioned range is completed. Then, the formed precast members (31a to 31d) are lifted and removed from the curved formwork 51. As shown in FIG.

(construction of structure)
Next, a method of constructing the structure 15 on site will be described with reference to FIGS. 6 to 8. FIG.

As shown in FIG. 6(a), first, a plurality of pillars 20 and a floor 21 for supporting the structure are installed. In this embodiment, the pillar 20 and the floor 21 are also made of reinforced concrete, but are not limited to this.

Next, as shown in FIG. 6B, a pair of lower members 31 and 32 made of precast concrete are installed on the floor portion 21 . In this case, the reinforcing bars 31r and 32r protruding from the lower members 31 and 32 are arranged on the outside. Then, grout (or concrete) 22 is injected between the chamfered portion C<b>1 of the lower member 31 and the floor portion 21 . Also, grout (or concrete) 23 is injected between the lower member 31 and the lower member 32 . Grout (or concrete) 23 is also injected between the precast members (31a to 31d) constituting the lower members 31 and 32. As shown in FIG.

Next, as shown in FIG. 6(c), a sidewall formwork comprising a return formwork 71 and an outer formwork 72 is installed. Specifically, a return formwork 71 is installed inside the upper parts of the lower members 31 and 32 .
Further, an outer formwork 72 is installed so as to face the return formwork 71 . This outer formwork 72 is provided with an outward widened portion at the top. Each outer mold frame 72 is placed on both ends of the floor portion 21 at positions separated from the ends of the lower members 31 and 32 by a predetermined distance.

Next, reinforcing bars are arranged inside the return formwork 71 and the outer formwork 72 . Each reinforcing bar is arranged in a state of protruding above the upper surfaces of the return mold 71 and the outer mold 72 .

Next, as shown in FIG. 6D, side walls 25 are formed outside the lower members 31 and 32 . Specifically, concrete is poured between the return formwork 71 and the outer formwork 72 and compacted by a vibrator. Then, the return formwork 71 and the outer formwork 72 are removed.
In this case, as shown in FIG. 7, a side wall portion 25 is formed with a reinforcing bar 25r protruding from the top.

Next, as shown in FIG. 8A, shoring 74 is installed inside the lower members 31 and 32 . Then, the curved forms 51 and 52 are attached on the shoring 74 . In this case, the outer curved surfaces 51s, 52s of the curved molds 51, 52 and the inner curved surfaces 31s, 32s of the lower members 31, 32 are aligned so as not to cause a step. Furthermore, a formwork 75 is placed on the sides of the curved formworks 51 and 52 .

Then, upper members 26 and 27 are formed above the lower members 31 and 32, as shown in FIG. 8(b). Specifically, concrete is poured into the space surrounded by the curved formwork 51, 52 and the formwork 75, and compacted by a vibrator. In this case, along the outer curved surfaces 51s and 52s of the curved forms 51 and 52, inner curved surfaces 26s and 27s are formed as second smooth surfaces facing downward (third direction).
After that, the curved formwork 51, 52 and the formwork 75 are removed. As described above, the structure 15 shown in FIG. 2 is completed.

According to this embodiment, the following effects can be obtained.
(1) In the present embodiment, the structure 10 is formed by forming the lower member 12 in advance with the inner curved surface 12s, which is required to be smooth, facing downward, and installing the lower member 12 upside down. Further, the lower members 31 and 32 are formed with the inner curved surfaces 31s and 32s facing downward, and the structure 15 is installed with the inner curved surfaces 31s and 32s facing upward. As a result, free matter that emerges when the concrete hardens does not stay on the inner curved surface 12s and the inner curved surfaces 31s and 32s, so that a smooth surface can be achieved. In addition, since the lower members 31 and 32 are made of precast members (31a to 31d) formed in advance, the structure 15 can be efficiently installed on site.

(2) In the present embodiment, the lower members 12, 31, 32 are formed by curved molds provided with outer curved surfaces 50s, 51s, 52s along the inner curved surfaces 12s, 31s, 32s of the lower members 12, 31, 32. 50, 51, 52 are used. As a result, any smooth curved surface can be efficiently formed by using the formwork.

(3) In the present embodiment, the upper part of the pedestal 60 on which the curved formwork 51 is placed is configured to have a trapezoidal shape in which the inner part 51a of the curved formwork 51 is fitted. As a result, the curved formwork 51 can be firmly supported from the inside, so that the outer curved surface 51s is difficult to deform, and the inner curved surfaces 31s and 32s can be accurately formed along the outer curved surface 51s.

(4) In the present embodiment, partition plates 65 are placed on one curved formwork 51 according to the range of one concrete placement, and concrete is placed in the areas partitioned by the partition plates 65. Each precast member (31a-31d) is formed. As a result, a plurality of precast members (31a to 31d) are formed using one continuous curved surface formwork 51, so even if the timing of concrete placement is different, the boundary portions of the respective precast members (31a to 31d) (Joint portion) can be formed smoothly and continuously.

(5) In this embodiment, the upper members 26 and 27 are formed using the curved forms 51 and 52 used to form the lower member 31 . Thereby, the structure 15 can be formed using the same curved molds 51 and 52 .
(6) In this embodiment, the upper members 26 and 27 formed above the lower member 31 are concreted on site. Thereby, the upper members 26 and 27 which do not need to be turned upside down can be formed by casting in place.

(7) In the present embodiment, the lower members 31 and 32 are arranged so that the reinforcing bars 31r and 32r protrude outward, and the side walls 25 are formed by incorporating the protruding ends of the reinforcing bars 31r and 32r. Thereby, the lower members 31, 32 and the side wall portion 25 can be integrated by the reinforcing bars 31r, 32r.

This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
- In the above-described embodiment, the upper members 26 and 27 are formed above the installed lower members 31 and 32 by casting in place. The configuration of the upper member is not limited to this, and like the lower member, it may be formed as a precast member and installed on site.

- In the above embodiment, the curved forms 51 and 52 are attached on the shoring 74, and the upper members 26 and 27 are constructed at the same time. As with the lower members 31 and 32, the upper members 26 and 27 may also be constructed one side at a time using a single curved formwork. In this case, only one curved formwork should be prepared.

In the above-described embodiment, the lower members 31 and 32 of the structure 15 are described as having the same curved shape of a square with rounded corners having circular arcs. The shape of the pair of lower members is not limited to the same shape, and may be a combination of a curved surface and a flat surface, or an asymmetrical shape. Here, when the cross section of a pair of lower members is bilaterally symmetrical, the same curved formwork may be used.

For example, FIG. 9 shows a lower right member 81 and a lower left member 82 of a structure having rounded corners, which is substantially rectangular with respect to its width. 9(a) and 9(b) are top and cross-sectional views of the right lower member 81, and FIGS. 9(c) and 9(d) are top and cross-sectional views of the left lower member 82. there is The right lower member 81 and the left lower member 82 are formed using the same curved formwork 77 . In this case, the formwork 78 is arranged so as to deviate from the central axis 77 c of the curved formwork 77 . Then, concrete is poured into the space surrounded by the formwork 78 on the curved formwork 77 to form the right lower member 81 and the left lower member 82 . Thereby, even if the right and left lower members (81, 82) do not have the same shape, the lower members (81, 82) can be formed using one curved mold 77.

- In the above-described embodiment, the structure 15 is formed with the inner curved surface 15s for forming a space in which the cross section continuously changes from a circular shape to a rounded square shape. The formed smooth surface is not limited to the inner curved surface formed inside the structure. For example, a structure having a smooth outer curved surface may be formed.

FIG. 10 shows a cross-sectional view of a structure 85 having an outer curved surface 85s. The outer curved surface 85s of this structure 85 is a smooth surface that is a continuous upwardly convex curved surface and a downwardly convex curved surface. Here, using a formwork having a curved surface shaped along the outer curved surface 85s, the structure 85 is configured as a precast member with the outer curved surface 85s facing downward, and installed upside down. Further, the smooth surface is not limited to a curved surface, and may be a complex-shaped surface including a flat inclined surface in part.

- In the above embodiment, the lower members 12, 31, 32 are formed with the inner curved surfaces 12s, 31s, 32s facing downward. The direction in which the smooth surface is formed (second direction) is not limited to the downward direction, and may be any direction different from the direction in which free matter is released. For example, it may be obliquely downward.

In addition, the first direction in which the smooth surface provided in the structure faces is not limited to the same direction (upward direction) as the direction in which loose matter emerges. For example, even if the structure 85 shown in FIG. 10 is arranged to extend in the vertical direction, it is possible to form a smooth smooth surface by constructing in the same manner.

- In the above embodiment, the lower member 31 is composed of a plurality of precast members (31a to 31d). Depending on the size of the structure, the lower member 31 may be constructed from a single precast member.

Next, technical ideas that can be grasped from the above-described embodiment and another example will be added below together with their effects.
(a) The method of constructing a structure according to any one of claims 1 to 3, wherein the smooth surface is a curved surface.
Therefore, according to the invention described in (a), it is possible to form a smooth surface on a curved surface that is difficult to plaster.
(b) The method of constructing a structure according to (a) above, wherein the smooth surface is a curved surface having a cross section formed by continuously forming circular arcs with different curvatures in the longitudinal direction.
Therefore, according to the invention described in (b), it is possible to smoothly form a curved surface in which arc cross sections having different curvatures are continuously formed.

C1... chamfered portion, P1... opening, 10, 15, 85... structure, 11, 26, 27... upper member, 11s, 12s, 15s, 26s, 27s, 31s, 32s... inner curved surface, 12, 31, 32 ... Lower member as a precast member 20 ... Column 21 ... Floor section 22, 23 ... Grout material 25 ... Side wall section 25r, 31r, 32r ... Reinforcement bar 31a, 31b, 31c, 31d ... Precast member 50, 51, 52, 77 curved formwork, 50s, 51s, 52s, 85s outer curved surface as forming surface 51a, 52a inner portion 60 frame 61 H-shaped steel 65 partition plate 71 return Formwork 72 Outer formwork 74 Shoring 75, 78 Formwork 77c Center line 81 Right lower member 82 Left lower member.

Claims (2)

1. A method of constructing a structure having in place a smooth surface of a precast member of concrete and having an axially extending shape, comprising the steps of:
A formwork having a formation surface corresponding to the planar shape of the smooth surface so that the smooth surface of the precast member is arranged in a downward direction opposite to the upward direction in which loose matter in the concrete at the time of placing is placed. and
In the formwork, a plurality of partition plates arranged at positions corresponding to the range of concrete to be cast in one time are erected at intervals in the axial direction, and concrete is poured into a plurality of divisions. forming a precast member;
A method of constructing a structure, comprising constructing the structure by arranging the precast members obtained by uniting the divided precast members so that the smooth surface is at the predetermined position. 2. The method of constructing a structure according to claim 1, wherein the precast member has a shape formed by the smooth surface that changes in the axial direction.

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