Structural components for water storage tanks

Abstract

To provide a structural component for a water storage tank that can withstand a larger load without increasing the thickness of the support legs. [Solution] The outer circumferential surface of the support leg that receives the load of the structural member for the water storage tank is made into a shape in which multiple element members are connected. The element members have a U-shaped trough cross-section, and the width of the bottom surface of the trough shape narrows from the base to the tip. The outer circumferential surface of the support leg is made up of these element members connected to each other with the open side of the trough shape facing inward. Furthermore, the width of the bottom surface of the trough shape at the tip is in the range of 1 to 2 times the width of the side surface of the trough shape, and the outer circumferential surface of the support leg is made up of a number of such element members ranging from 6 to 10.

Description

Technical Field

[0001] The present invention relates to a structural member for a water storage tank that includes a base and support legs erected from the back surface of the base to support the base, and forms a water storage space of the water storage tank by arranging a plurality of them in a stacked state.

Background Art

[0002] In residential areas where a large number of people live, it is common for most of the ground to be paved with asphalt or the like. When the ground is paved, it becomes difficult for rainwater and the like to penetrate into the ground, so urban water disasters such as floods are likely to occur. As one of the countermeasures, it is known to install a water storage tank underground. If a large amount of rainwater can be stored in the water storage tank, it is possible to prevent the occurrence of urban water disasters by gradually infiltrating the stored rainwater into the ground or gradually discharging it into rivers.

[0003] As a technology that enables easy installation of a water storage tank underground, a technology for forming a water storage tank by stacking a plurality of structural members is known (for example, Patent Document 1). The structural member includes a rectangular base and a plurality of support legs erected from the lower surface of the base to support the base, and a water storage tank can be easily installed underground as follows. First, a hole is dug in the ground to form a recess, and after leveling the bottom surface of the recess, a plurality of structural members are arranged in a planar shape. At this time, the structural members may be arranged in their original orientation (that is, the orientation with the base on top and the support legs on the bottom), but if the structural members are arranged in the upside-down orientation (the orientation with the base on the bottom and the support legs on the top), a plurality of structural members can be easily arranged on the bottom surface of the recess.

[0004] After arranging multiple structural members on a plane, multiple more structural members are then arranged on top of them in a plane. The structural members placed on top of the structural members may be placed upside down or in their original orientation. In this case, the structural members are mounted with the tips of the support legs, which are erected upward from the base of the lower structural member, butting together with the tips of the support legs, which are erected downward from the base of the upper structural member. By stacking multiple structural members in this manner in multiple layers, a large layered structure made of multiple structural members can be formed underground.

[0005] The resulting laminated structure has a large space inside that is supported by multiple support legs. By utilizing this space as a water storage area, a large water storage tank can be easily installed underground. Furthermore, by covering the top surface of the laminated structure with soil or paving it, the ground where the water storage tank is buried can be used as a garden or parking lot. When the ground above the water storage tank is used in this way, a large load is placed on the laminated structure, but since there are many support legs inside the laminated structure, these support legs can distribute and support the load. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 5006072 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in recent years, there has been a demand to install water storage tanks at greater depths underground, or to install heavier structures on the ground above the water storage tanks. Consequently, it has become necessary to increase the load that the support legs can withstand. While it is possible to withstand greater loads by making the support legs thicker, this is undesirable because it narrows the water storage space inside the laminated structure, reducing the capacity of the water storage tank.

[0008] This invention was made to solve the aforementioned problems of conventional structural members for water storage tanks, and aims to provide a structural member for a water storage tank that can withstand a larger load without increasing the thickness of the support legs. [Means for solving the problem]

[0009] To solve the above-mentioned problems, the structural member for the first water storage tank of the present invention employs the following configuration: A structural member for a water storage tank, comprising a base and support legs erected from the underside of the base to support the base, and arranged in multiple stacked configurations to form the water storage space of the water storage tank, The support leg has an outer peripheral surface, The cross-section is a U-shaped trough, and multiple element members erected from the base are connected at their side ends with the open side of the trough facing inward. The element member has a bottom surface width that narrows from the base to the tip, and at the tip, the bottom surface width of the bottom surface and the side surface width of the bottom surface are substantially the same. The outer surface of the support leg is formed by six to ten of the element members. It is characterized by the following:

[0010] In the first structural member for a water storage tank of the present invention, the outer surface of the support leg is shaped by connecting multiple element members. Here, the element members are trough-shaped members with a U-shaped cross-section, erected from the base, and the width of the bottom surface of the trough shape narrows from the root side to the tip side. The outer surface of the support leg is shaped in such a way that these element members are connected at their side ends with the open side of the trough shape facing inward. The element members forming the support leg have substantially the same width at the tip of the trough shape as the width of the side of the trough shape, and the outer surface of the support leg is formed using 6 to 10 such element members.

[0011] While the detailed reasons will be explained later, to increase the strength of the support legs and thereby the load-bearing capacity of the structural members for the water storage tank, it is considered most effective to increase the strength of the tip portion of the support legs. To increase the strength of the tip portion of the support legs, it is effective to form the outer circumferential side surface of the support leg with a trough-shaped element member, with the open side of the trough facing inward and the side ends of the element members connected. In particular, it is considered effective to use an element member whose tip portion has substantially the same width as the width of the bottom surface of the trough shape. However, if the thickness of the support leg is to remain constant, the cross-section of each element member needs to be made smaller as the number of element members forming one support leg increases. It is known that if the cross-section of the element member is too small or too large, the effect of increasing the strength of the support leg will not be obtained. Therefore, if the outer circumferential side surface of the support leg is formed using a range of 6 to 10 element members, the strength of the tip portion of the support leg can be increased. As a result, it becomes possible to increase the strength of the support legs without making the support legs thicker, thereby providing a structural member for a water storage tank that can withstand a larger load.

[0012] Furthermore, in order to solve the above-mentioned problems, the structural member for the second water storage tank of the present invention employs the following configuration. That is, A structural member for a water storage tank, comprising a base and support legs erected from the underside of the base to support the base, and arranged in multiple stacked configurations to form the water storage space of the water storage tank, The support leg has an outer peripheral surface, The cross-section is a U-shaped trough, and multiple element members erected from the base are connected at their side ends with the open side of the trough facing inward. The element member has a bottom surface width that narrows from the base to the tip, and at the tip, the bottom surface width of the bottom is 1 to 2 times the width of the side surface of the bottom. The outer surface of the support leg is formed by six of the element members. It is characterized by the following:

[0013] As will be explained in detail later, it has been found that the effect of increasing the strength of the tip of the support leg decreases as the width of the bottom surface of the trough shape at the tip increases relative to the width of the side surface of the trough shape. Furthermore, it has been found that the relationship between the number of element members forming the support leg and the effect of increasing the strength of the tip of the support leg is greatest when there are six members. Therefore, when there are six element members, the strength of the tip of the support leg can be increased even when using element members where the width of the bottom surface of the trough shape at the tip is 1 to 2 times the width of the side surface. As a result, it is possible to provide a structural member for a water storage tank that can withstand a larger load without making the support leg thicker.

[0014] Furthermore, in order to solve the above-mentioned problems, the third structural member for a water storage tank of the present invention employs the following configuration. That is, A structural member for a water storage tank, comprising a base and support legs erected from the underside of the base to support the base, and arranged in multiple stacked configurations to form the water storage space of the water storage tank, The support leg has an outer peripheral surface, The cross-section has a U-shaped gutter shape, and a plurality of element members erected from the base are in a shape where the side ends of the element members are connected with the open side surface of the gutter shape facing inward. The element member has a width of the bottom surface of the gutter shape that narrows from the root side to the tip side, and at the tip portion, the width of the bottom surface of the gutter shape is 1 to 1.5 times the width of the side surface of the gutter shape. The outer peripheral side surface of the support leg is formed by eight of the element members. It is characterized by this.

[0015] As will be described later, it has been found that the relationship between the number of element members forming the support leg and the effect of increasing the strength of the tip portion of the support leg is that the effect in the case of eight is greater than that in the case of six. Therefore, when the number of element members is eight, even when using an element member where the width of the bottom surface of the gutter shape at the tip portion is 1 to 1.5 times the width of the side surface, it is possible to increase the strength of the tip portion of the support leg. As a result, it is possible to provide a structural member for a water storage tank that can withstand a larger load without making the support leg thicker.

Brief Explanation of Drawings

[0016] [Figure 1] It is a perspective view showing the overall shape of the structural member 10 for a water storage tank of this embodiment. [Figure 2] It is a perspective view showing the detailed shape of the unit unit 11 forming the structural member 10 of this embodiment. [Figure 3] It is an explanatory view showing a state where the structural members 10 of this embodiment are laminated to form a laminated structure 1. [Figure 4] It is an explanatory view showing a state where a plurality of structural members 10 are stacked and stored. [Figure 5] It is a perspective view showing the outer shape of the support leg 13 adopted in the structural member 10 of this embodiment. [Figure 6] It is an explanatory view showing the cross-sectional shape of the support leg 13 taken at three locations near the tip, near the middle, and near the root of the support leg 13. [Figure 7]It is an explanatory diagram showing the shape of the support leg 93 of the conventional unit 91. [Figure 8] It is an explanatory diagram showing the state where the conventional support leg 93 collapses and is deformed. [Figure 9] It is an explanatory diagram showing the reinforcement position of the support leg 93 where it is considered that the collapse deformation can be most effectively suppressed by the conventional support leg 93. [Figure 10] It is an explanatory diagram about the reason why it is considered that the deformation at the tip part causes the collapse deformation in the conventional support leg 93. [Figure 11] It is an explanatory diagram showing the shape of the element member 14 forming the support leg 13 of the present embodiment. [Figure 12] It is an explanatory diagram showing that there is an allowable range in the number of the element members 14 that can be used to form one support leg 13. [Figure 13] It is an explanatory diagram about the element member 14 of the first modification example. [Figure 14] It is an explanatory diagram about the element member 14 of another aspect of the first modification example. [Figure 15] It is an explanatory diagram about the support leg 13 of the second modification example. [Figure 16] It is an explanatory diagram showing the reason why the strength of the support leg 13 of the second modification example increases. [Figure 17] It is an explanatory diagram showing the correspondence relationship between the fitting convex portion 15 formed at the tip of the support leg 13 and the fitting concave portion 14d of another support leg 13 into which the fitting convex portion 15 fits. [Figure 18] It is an explanatory diagram about the shape of the fitting convex portion 15 formed on the support leg 13 of the third modification example. [Figure 19] It is an explanatory diagram showing the desirable conditions for the shape of the fitting convex portion 15 formed on the support leg 13 of the third modification example.

MODE FOR CARRYING OUT THE INVENTION

[0017] Figure 1 is a perspective view showing the overall shape of the structural member 10 for the water storage tank in this embodiment. The structural member 10 in this embodiment has a structure in which four unit units 11 made of hard resin such as PP (polypropylene) are arranged, and each unit unit 11 has a rectangular base 12 and four support legs 13 erected downward from the four corners on the back surface of the base 12. The four bases 12 are arranged in a grid pattern in two rows vertically and horizontally, and the sides of adjacent bases 12 are connected by a bridging section (not shown). Therefore, by cutting the bridging section, one structural member 10 can be divided into two or four relatively easily.

[0018] Figure 2 is a perspective view showing the detailed shape of the unit unit 11 that forms the structural member 10 of this embodiment. The base 12 of the unit unit 11 has a structure in which plate-shaped ribs 12b are erected in a grid pattern on both sides of a rectangular plate-shaped member 12a to provide strength, and support legs 13 are erected downwards from the four corners of the base 12. In addition, although it is omitted from the drawing to avoid making the drawing complicated, a through hole is formed in the center of the plate-shaped member 12a in the part surrounded by the grid-like ribs 12b.

[0019] The support leg 13 has a hollow structure, and at the point where the support leg 13 is connected to the base 12, the internal space of the support leg 13 opens into the plate-shaped member 12a of the base 12, forming a large opening 12c. In this embodiment, the structural member 10 is made up of four unit units 11 connected together, so the base 12 of the unit unit 11 corresponds to the "base" of the present invention, and the support leg 13 of the unit unit 11 corresponds to the "support leg" of the present invention. In addition, the support leg 13 in this embodiment has a special shape, which will be explained in detail later. Furthermore, instead of making the inside of the support leg 13 a simple hollow structure, reinforcing ribs may be provided protruding from the inner wall surface of the support leg 13. In addition, as will be described later, the support leg 13 needs to have a structure that allows other support legs 13 to be inserted through the opening 12c of the base 12 (nesting structure), and if reinforcing ribs are simply provided protruding from the inner wall surface, other support legs 13 cannot be inserted, and therefore the nesting structure cannot be made. However, if the reinforcing ribs are attached to the tip side of the support leg 13, it will not interfere with the insertion of other support legs 13. Therefore, the reinforcing ribs can be attached to the inner wall surface while maintaining the nesting structure.

[0020] Figure 3 is an explanatory diagram showing how the structural members 10 of this embodiment are stacked. In the illustrated example, multiple structural members 10 are arranged in a planar configuration with their tops and bottoms inverted, and then multiple structural members 10 are placed on top of them in their normal orientation. At this time, the support legs 13 and tips of the inverted lower structural members 10 are brought into contact with the tips of the support legs 13 of the normally oriented upper structural members 10, and the multiple structural members 10 are placed accordingly. Then, the base 12 of the inverted structural member 10 is placed on top of the base 12 of the normally oriented upper structural member 10. By repeating this process to stack the structural members 10, a large stacked structure 1 can be formed by stacking multiple structural members 10 in many layers. If such a stacked structure 1 is formed underground, it can be used as a water storage tank.

[0021] Furthermore, the support legs 13 of the structural member 10 have a tapered shape that narrows from the base to the tip, and the support legs 13 are hollow. As a result, the structural member 10 has a nesting structure that allows the support legs 13 of one structural member 10 to be inserted inside the support legs 13 of another structural member 10 and stacked. By stacking multiple structural members 10 in this way, a large number of structural members 10 can be stored in a small space. In the example shown in Figure 3, 12 structural members 10 are used, but as shown in Figure 4, they can be compactly arranged. As a result, even when a large number of structural members 10 are required to install a water storage tank, these structural members 10 can be easily transported to the installation site. In this embodiment, the structural member 10 employs support legs 13 with a special shape as described below in order to provide sufficient strength to the support legs 13 while maintaining the nesting structure.

[0022] Figure 5 is a perspective view showing the external shape of the support leg 13 used in the structural member 10 of this embodiment. Figure 5(a) shows the unit unit 11 in an inverted orientation. When the unit unit 11 is inverted, four support legs 13 are erected from the four corners of the base 12. Figure 5(b) shows a magnified view of the external shape of one of the support legs 13. As shown in Figure 5(b), the support leg 13 of this embodiment has a shape like a bundle of multiple element members 14. In the illustrated example, six element members 14 are bundled in a ring shape, and three of the element members 14, every other one, have a fitting projection 15 protruding from their tip. The tips of the three element members 14 that do not have a fitting projection 15 are recessed relative to the fitting projection 15, forming a fitting recess 14d. Although the fitting projection 15 is formed integrally with the element member 14, the fitting projection 15 is ultimately an addition to the element member 14. Therefore, in the example shown in Figure 5, the portion formed by bundling together the six element members 14 corresponds to the "support leg" in this invention.

[0023] Figure 6 is an explanatory diagram showing the detailed shape of the support leg 13 by taking cross-sections at three locations: near the tip of the support leg 13 (position AA in Figure 5(b)), near the middle (position BB in Figure 5(b)), and near the base (position CC in Figure 5(b)). Figure 6(a) shows the cross-sectional shape of the support leg 13 near the tip. As shown in the figure, the cross-section of the support leg 13 is a shape made up of six element members 14 assembled together, and the cross-sectional shape of each element member 14 is U-shaped. Here, a U-shaped shape is a shape in which the side sides (hereinafter referred to as side sides) are erected from both sides of the central side (hereinafter referred to as the center side). The six element members 14 are connected at the tips of the side sides of adjacent element members 14 with the open side of the U-shape facing inward. Also, near the tip of the support leg 13, the length Lc of the center side and the length Ls of the side sides are approximately the same.

[0024] In the actual support leg 13, the connection between the center side and the side side forming the U-shape is formed in an arc shape. Also, the connection between the side side and the adjacent side side of the U-shape is also formed in an arc shape. For this reason, it can be difficult to determine the length Lc of the center side and the length Ls of the side side. In such cases, the length Lc of the center side and the length Ls of the side side can be determined by assuming that the center side and the side side are directly connected (without the arc-shaped portion), and further, assuming that the side side and the adjacent side side are directly connected (without the arc-shaped portion).

[0025] Figure 6(b) shows the cross-sectional shape of the support leg 13 near the middle (position BB in Figure 5(b)). Near the middle, the cross-section of the support leg 13 is such that six U-shaped element members 14 are connected at the tips of the side edges of adjacent element members 14, with the open sides of the U-shapes facing inward. Also, near the middle of the support leg 13, the length Ls of the side edges is approximately the same as the length of the side edges near the tip, but the length Lc of the center edge is longer than the length of the center edge near the tip.

[0026] Figure 6(c) shows the cross-sectional shape of the support leg 13 near the base (position CC in Figure 5(b)). Near the base, as with the tip and middle sections described above, the cross-section of the support leg 13 is formed by connecting six U-shaped element members 14. Near the base of the support leg 13, the length Ls of the side edges is approximately the same as the length of the side edges near the middle section, but the length Lc of the center edge is further extended than the length of the center edge near the middle section. The support leg 13 in this embodiment has this shape in order to provide sufficient strength to the support leg 13 while maintaining the nesting structure of the unit unit 11. According to the inventors of this application, by giving the support leg 13 this shape, the strength of the support leg 13 can be improved without making the support leg 13 thicker or increasing its wall thickness (and thus without increasing its weight), and the nesting structure of the unit unit 11 can also be maintained. This shape was created by the inventor of the present invention by reconsidering the shape of the support leg 13 from a completely opposite perspective to that of the conventional design. As preparation for explaining this point, the shapes of conventional support legs of structural members will be briefly described.

[0027] Figure 7 is a perspective view showing the general shape of a conventional structural member unit 91. Conventional structural members are formed by arranging such unit units 91 in two rows, vertically and horizontally, and connecting adjacent unit units 91. In Figure 7, the unit units 91 are shown upside down to make the shape of the support legs 93 easier to understand. As shown in the figure, the support legs 93 of a conventional unit unit 91 are erected from the four corners of a rectangular base 92. The shape of the support legs 93 is a rectangular prism with a rectangular cross-section that tapers towards the tip.

[0028] As shown in Figure 8, it is known that in conventional structural members, if a load exceeding the limit is applied from above, the support legs 93 of the unit unit 91 will break. Furthermore, it is known that the manner of failure is such that the support legs 93 deform by collapsing while maintaining the axial orientation of the support legs 93. It is also known that the area where this collapsing deformation occurs is the area slightly towards the tip near the middle of the support leg 93 (the area shaded in Figure 8(a)), and furthermore, as shown by the dashed line in Figure 8(b), it is known that the manner of collapsing deformation is such that opposing sides of the support leg 93 bulge outward and the remaining opposing sides sink inward. For this reason, conventionally, when it became necessary to increase the strength of the support legs 93, it was common practice to increase the strength of the area prone to collapsing deformation (i.e., near the middle of the support leg 93) by increasing the overall thickness of the support leg 93 or by forming reinforcing ribs in the area from the base to beyond the middle.

[0029] However, according to the inventor of this application, the area where the real need to increase strength is not the middle section, which is prone to crushing deformation, but the tip section, where crushing deformation does not occur (see Figure 9). The reason for this reasoning is as follows. First, as mentioned above using Figure 4, the structural member 10 needs to have a nesting structure, so the support leg 93 is hollow and tapered. Therefore, the cross-sectional area of ​​the support leg 93 is smallest near the tip, the pressure due to the load is greatest near the tip, and it is also near the tip that it is most prone to deformation. However, crushing deformation actually occurs near the middle of the support leg 93. The reason for this is that even though the deformation occurs near the tip, the effects of that deformation are most apparent near the middle of the support leg 93, and for this reason, crushing deformation is more likely to occur near the middle. This point will be explained in more detail.

[0030] In many cases, the load on the support leg 93 is not applied directly to the side of the support leg 93, but rather to the top portion of the support leg 93, and then transmitted to the side via the top portion. Therefore, as shown in Figure 10, the top portion 93a of the support leg 93 flexes slightly under load, and as a result, the side portion 93b of the support leg 93 deforms by bulging outward. The deformation of the side portion 93b is slight, but the effect of the deformation increases as it moves away from the top portion 93a. For this reason, the effect of the deformation becomes large near the middle of the support leg 93, and as a result, it is thought that the support leg 93 cannot withstand the load and collapses. Based on this consideration, if the deformation of the side portion 93b bulging outward at the tip of the support leg 93 can be suppressed, it should be possible to suppress the collapse deformation of the support leg 93. As a result, it is thought that the strength of the support leg 93 can be effectively increased without increasing the overall thickness of the support leg 93 or forming reinforcing ribs in the range from the base to the middle.

[0031] Based on the above ideas, the inventors of the present invention conducted further studies and came up with the idea of ​​forming a support leg 13 by combining gutter-shaped element members 14 as shown in Figure 11. As shown in the figure, the element member 14 has a U-shaped cross-section, and the whole is gutter-shaped. In addition, the width of the bottom surface 14a of the gutter shape (corresponding to the center side 14c of the U-shape) increases towards the bottom of the element member 14, but the width of the side surface 14b of the gutter shape (corresponding to the side sides 14s of the U-shape) is almost the same from the top end to the bottom end of the element member 14.

[0032] Furthermore, instead of making the support leg 13 a simple rectangular prism shape like the conventional support leg 93 shown in Figure 7, we considered a shape obtained by arranging multiple element members 14 with the open side of the gutter shape facing inward, and connecting the sides 14b of adjacent element members 14 at their ends. The support leg 13 of this embodiment, as described above with reference to Figures 5 and 6, is formed in this manner.

[0033] In this embodiment, even if the support leg 13 formed in this manner attempts to deform so that the bottom surface 14a of the element member 14 bulges outward (see dashed line in Figure 10), the deformation can be suppressed by the side surfaces 14b on both sides of the bottom surface 14a. In addition, since the width of the bottom surface 14a of the element member 14 narrows towards the top, deformation that causes the bottom surface 14a to bulge outward can be almost completely suppressed near the top end of the element member 14. Furthermore, if the width of the side surface 14b (Ls in Figure 11) were to be longer than the width of the bottom surface 14a (Lc in Figure 11) near the top end of the element member 14, there would be a risk that the side surfaces 14b of the element member 14 would deform so that they bulge outward. However, in this embodiment, the width of the bottom surface 14a (Lc in Figure 11) and the width of the side surface 14b (Ls in Figure 11) near the top end are approximately the same length. Therefore, deformation in which the side surface 14b of the element member 14 bulges outward can be suppressed almost completely.

[0034] Furthermore, when we actually fabricated and experimented with a prototype of the support leg 13 based on this idea, we found that there are limitations on the number of element members 14 that can be used to form the support leg 13, and that 6 to 10, preferably 6 to 8, is ideal. The reason for this will be explained below.

[0035] Figure 12 is an explanatory diagram showing the cross-sectional shape near the tip of a support leg 13 (position AA in Figure 5(b)) when the number of element members 14 forming a single support leg 13 is changed in the range of 4 to 12. Note that in Figure 12, the thickness of the support leg 13 is assumed to be the same as that of a conventional support leg 93. As can be immediately understood from Figure 12, the more element members 14 that form a single support leg 13 there are, the smaller the cross-section of each individual element member 14 must be.

[0036] For example, Figure 12(a) shows a case where four element members 14 are used. However, in order to make the thickness of the support leg 13 the same as that of the conventional support leg 93, it becomes necessary to use element members 14 with longer center side length Lc and side side length Ls. When the length of the center side 14c and side side length Ls are increased, deformation such as outward bulging of the bottom surface 14a and side surface 14b of the element member 14 becomes more likely. If an element member 14 with a small cross-section (i.e., an element member 14 with a short center side length Lc and side side length Ls) is used to avoid this, the thickness of the support leg 13 becomes thinner, and as a result, the strength of the support leg 13 decreases. Therefore, when there are four element members 14, it is difficult to fully utilize the inventor's idea of ​​this application.

[0037] Figure 12(b) shows the case where a support leg 13 is formed using six element members 14, Figure 12(c) shows the case where eight element members 14 are used, and Figure 12(d) shows the case where ten element members 14 are used. The greatest effect is obtained when using six element members 14 as shown in Figure 12(b), but a nearly equivalent effect is obtained when using eight element members 14 as shown in Figure 12(c). Furthermore, when using ten element members 14 as shown in Figure 12(d), a reasonable effect is observed, but it is smaller than when using six or eight element members 14.

[0038] The reason why the effect decreases when the number of element members 14 used is increased to 10 is thought to be because the length of the side edge 14s near the upper end of the element member 14 becomes shorter. That is, as mentioned above using Figure 11, the side surface 14b of the element member 14 has the effect of suppressing the deformation that causes the bottom surface 14a to bulge outward. And it is thought that this effect is most needed near the tip of the support leg 13 (near the upper end of the element member 14). Here, as is clear from comparing Figures 12(b) to 12(d), the length of the side edge 14s at the upper end of the element member 14 becomes shorter as the number of element members 14 is increased from 6 to 8 to 10. As a result, it is thought that it becomes difficult to suppress the deformation that causes the bottom surface 14a of the element member 14 to bulge outward.

[0039] Furthermore, Figure 12(e) shows the case where a support leg 13 is formed using 12 element members 14. When 12 element members 14 are used, the length of the side edge 14s at the upper end of the element member 14 becomes shorter. As a result, it becomes difficult to suppress the deformation of the bottom surface 14a of the element member 14 that tends to bulge outward, and the effect of suppressing the crushing deformation of the element member 14 is not obtained. Therefore, in order to prevent the crushing deformation of the support leg 13 based on the inventor's idea of ​​the present application, it is considered necessary to limit the number of element members 14 used to form one support leg 13 to preferably 6 to 8, and at most 10.

[0040] As explained in detail above, in order to prevent the support leg 13 from collapsing even under heavy load, it is important to increase the strength near the tip of the support leg 13. To achieve this, the support leg 13 can be formed using multiple element members 14 with the shape shown in Figure 11. In the element member 14 shown in Figure 11, the length Lc of the center side 14c and the length Ls of the side side 14s are approximately the same near the upper end. By using such an element member 14, the strength near the tip of the support leg 13 can be reliably increased. Furthermore, if the number of element members 14 used to form one support leg 13 increases, the side side 14s near the upper end of the element member 14 becomes shorter, making it difficult to sufficiently suppress the deformation of the bottom surface 14a of the element member 14 bulging outwards. For this reason, the number of element members 14 should be 6 to 8 (at most 10).

[0041] However, the fact that the strength of the support legs 13 can be increased even when there are 10 element members 14 means that if the length of the side edge 14s of the element member 14 is about Ls10, as shown in Figure 12(d) for when there are 10 element members 14, then deformation that causes the bottom surface 14a of the element member 14 to bulge outwards can be suppressed. Therefore, as shown in Figure 11, the length Lc of the center edge 14c near the top end of the element member 14 and the length Ls of the side edge 14s do not necessarily have to be the same. As long as a length of about Ls10 for the side edge 14s in Figure 12(d) can be secured, it is thought that the strength of the support legs 13 can be increased even if the center edge 14c is longer than the side edge 14s.

[0042] Figure 13 is an explanatory diagram illustrating a first modified element member 14 in which the center side 14c is longer than the side side 14s, based on the above-described concept. Figure 13(a) shows the external shape of the first modified element member 14. In the illustrated first modified element member 14, the length Lc of the center side 14c near the upper end is set to approximately twice the length Ls of the side side 14s. Figure 13(b) shows the cross-sectional shape near the tip of a support leg 13 formed using six such first modified element members 14. As shown, the length of the side side 14s near the tip of the support leg 13 is almost the same as the length Ls10 of the side side 14s in Figure 12(d). Conversely, when forming a support leg 13 using six element members 14, it is considered possible to increase the strength of the support leg 13 even if the length Lc of the center side 14c at the upper end of the element member 14 is made to twice the length Ls of the side side 14s.

[0043] Figure 14 is an explanatory diagram illustrating another embodiment of the element member 14 in which the center side 14c is longer than the side side 14s of the first modification. Figure 14(a) shows the external shape of the element member 14 in another embodiment of the first modification. In the other embodiment of the element member 14 shown, the length Lc of the center side 14c near the top is set to be approximately 1.5 times the length Ls of the side side 14s. Figure 14(b) shows the cross-sectional shape near the tip of a support leg 13 formed using eight such other embodiment of the element member 14. As shown, the length of the side side 14s near the tip of the support leg 13 is almost the same as the length Ls10 of the side side 14s in Figure 12(d). Conversely, when forming a support leg 13 using eight element members 14, it is considered possible to increase the strength of the support leg 13 even if the length Lc of the center side 14c at the upper end of the element member 14 is increased to 1.5 times the length Ls of the side side 14s.

[0044] Furthermore, as described above, in this embodiment and the first modified example, the support leg 13 has a fitting projection 15 formed by extending the tip of the element member 14 that forms the outer peripheral side surface, and a flat surface (hereinafter referred to as the contact surface 15a) is formed at the tip of the fitting projection 15 (see Figure 5). Here, if the radius of the connection between the fitting recess 14d and the element member 14 is made larger than the radius of the connection between the contact surface 15a of the fitting projection 15 and the extended portion of the element member 14 (hereinafter referred to as the outer surface 15b of the fitting projection 15), the strength of the support leg 13 can be increased.

[0045] Figure 15 is an explanatory diagram of a second modified support leg 13 in which the radius of the connection portion between the fitting recess 14d and the element member 14 is set to be larger than the radius of the connection portion between the contact surface 15a and the outer surface 15b of the fitting projection 15. As shown in the figure, in the second modified support leg 13, the radius R1 of the connection portion between the fitting recess 14d and the element member 14 (hereinafter referred to as the outer radius R1 of the fitting recess 14d) is larger than the radius R2 of the connection portion between the contact surface 15a of the fitting projection 15 and the outer surface 15b of the fitting projection 15 (hereinafter referred to as the outer radius R2 of the contact surface 15a). This makes it possible to increase the strength of the support leg 13 for the following reasons.

[0046] First, as mentioned above, the support leg 13 has a tapered shape, and furthermore, the outer surface 15b of the fitting projection 15 is formed by extending the tip of the element member 14. Therefore, the outer surface 15b of the fitting projection 15 is located inward (towards the central axis of the support leg 13) than the element member 14 before extension. However, this is not very desirable from the standpoint of maintaining the strength of the support leg 13 in a structure in which multiple structural members 10 are stacked by butting the tips of the support legs 13 together.

[0047] Figure 16 is an explanatory diagram showing an enlarged view of the fitting portion between the tips of the support legs 13 of the two structural members 10 when the tips of the support legs 13 of the lower structural member 10 and the tips of the support legs 13 of the upper structural member 10 are abutted together and the two structural members 10 are stacked. Figure 16(a) shows the case where the outer radius R1 of the fitting recess 14d and the outer radius R2 of the contact surface 15a of the fitting projection 15 are equal.

[0048] As shown in Figure 16(a), when two structural members 10 are stacked, the support legs 13 of the lower structural member 10 support the load from the upper structural member 10, but the load on the lower support legs 13 is input from the upper support legs 13. In particular, where a fitting projection 15 is formed on the upper support leg 13, the load is input from the element member 14 of the upper support leg 13 to the fitting recess 14d of the lower support leg 13 via the outer surface 15b, and that load is input to the element member 14 of the lower support leg 13 via the fitting recess 14d. Also, where a fitting recess 14d is formed on the upper support leg 13, the load from the element member 14 of the upper support leg 13 is input to the element member 14 of the lower support leg 13 via the fitting recess 14d. Thus, when the outer radius R1 of the fitting recess 14d and the outer radius R2 of the contact surface 15a of the fitting projection 15 are equal, the load from the element member 14 of the upper support leg 13 is always input to the element member 14 of the lower support leg 13 via the upper or lower fitting recess 14d. As a result, there is a risk that the fitting recess 14d may collapse or bend, making the support leg 13 more susceptible to crushing deformation.

[0049] On the other hand, Figure 16(b) shows the case where the outer radius R1 of the fitting recess 14d is larger than the outer radius R2 of the contact surface 15a of the fitting projection 15. As shown in Figure 16(b), by making the outer radius R1 of the fitting recess 14d larger, the load from the element member 14 of the upper support leg 13 can be input to the element member 14 of the lower support leg 13 without going through the upper or lower fitting recess 14d. That is, at the location where the fitting projection 15 is formed on the upper support leg 13, the load input from the element member 14 of the upper support leg 13 via the outer surface 15b can be smoothly guided to the element member 14 by the portion of the lower support leg 13 with an outer radius R1. Also, at the location where the fitting recess 14d is formed on the upper support leg 13, the load input from the element member 14 of the upper support leg 13 can be smoothly guided to the element member 14 of the lower support leg 13 by the portion with an outer radius R1. In this way, since the load can be applied to the element member 14 of the lower support leg 13 without going through the fitting recess 14d, the fitting recess 14d will not collapse, nor will it bend, making the support leg 13 more susceptible to crushing deformation. As a result, it becomes possible to increase the strength of the support leg 13.

[0050] Furthermore, when forming the laminated structure 1 using the structural members 10 of this embodiment, the first modified example, and the second modified example described above, as shown in Figure 3, multiple structural members 10 with their tops and bottoms reversed are arranged horizontally, and then multiple structural members 10 in their original orientation are placed on top of them. At this time, the fitting projection 15 formed at the tip of the lower support leg 13 fits into the fitting recess 14d at the tip of the upper support leg 13, and the fitting projection 15 formed at the tip of the upper support leg 13 fits into the fitting recess 14d at the tip of the lower support leg 13. Therefore, the fitting projection 15 of the support leg 13 will always fit into one of the fitting recesses 14d of the other support leg 13.

[0051] Here, which fitting projection 15 of the support leg 13 fits into which fitting recess 14d of the other support leg 13 is determined by the orientation of the upper structural member 10 relative to the lower structural member 10. That is, as described above, the upper structural member 10 is the same as the lower structural member 10 with its top and bottom reversed, but there are three ways in which the top and bottom of the lower structural member 10 can be reversed. And, depending on which way the upper structural member 10 is the same as the lower structural member 10 with its top and bottom reversed, it is determined which fitting projection 15 of the support leg 13 fits into which fitting recess 14d of the other support leg 13.

[0052] Figure 17 is an explanatory diagram showing the relationship between the inversion of the upper and lower structural member 10 and the fitting recess 14d into which the fitting projection 15 of the support leg 13 fits. Figure 17(a) shows the inversion of the upper and lower structural member 10. There are three ways to invert the upper and lower structural member 10: inversion around either the left or right side of the structural member 10 (hereinafter referred to as the left-right inversion), as shown by the white arrows in the figure; inversion around either the front or rear side of the structural member 10 (hereinafter referred to as the rear inversion direction), as shown by the diagonal arrows in the figure; and inversion diagonally, as shown by the black arrows in the figure. The way the structural member 10 is inverted determines the fitting recess 14d into which the three fitting projections 15 formed at the tip of the support leg 13 fit.

[0053] Figure 17(b) shows three fitting protrusions 15 and three fitting recesses 14d formed at the tip of the support leg 13. When it is necessary to distinguish between these fitting protrusions 15, they will be referred to as fitting protrusion 15 "K", fitting protrusion 15 "M", and fitting protrusion 15 "N", respectively. Similarly, when it is necessary to distinguish between these fitting recesses 14d, they will be referred to as fitting recess 14d "p", fitting recess 14d "q", and fitting recess 14d "r", respectively.

[0054] As shown by the white arrow in Figure 17(a), when the structural member 10 is reversed in the left-right direction, the fitting projection 15 "K" in Figure 17(b) fits into the fitting recess 14d "p" of another support leg 13, the fitting projection 15 "M" fits into the fitting recess 14d "r" of another support leg 13, and the fitting projection 15 "N" fits into the fitting recess 14d "q" of another support leg 13. Furthermore, as shown by the black arrows in Figure 17(a), when the structural member 10 is reversed diagonally, the fitting projection 15 "M" in Figure 17(b) will fit into the fitting recess 14d "p" of another support leg 13, the fitting projection 15 "K" will fit into the fitting recess 14d "q" of another support leg 13, and the fitting projection 15 "N" will fit into the fitting recess 14d "r" of another support leg 13.

[0055] On the other hand, when reversing the structural member 10 in the backward direction (or forward direction), as shown by the shaded arrow in Figure 17(a), it is necessary to rotate another support leg 13 60 degrees (or 120 degrees, 180 degrees) clockwise (or counterclockwise) around its central axis. For example, if it is rotated 60 degrees clockwise, the fitting projection 15 "M" in Figure 17(b) will fit into the fitting recess 14d "q" of the other support leg 13, the fitting projection 15 "K" will fit into the fitting recess 14d "r" of the other support leg 13, and the fitting projection 15 "N" will fit into the fitting recess 14d "p" of the other support leg 13.

[0056] Thus, the fitting projection 15 formed at the tip of the support leg 13 fits into one of the three fitting recesses 14d of another support leg 13. The fitting recess 14d is formed between the two fitting projections 15. Therefore, the fitting projection 15 may have a shape that tapers toward the central axis of the support leg 13, with both sides of the tapered portion formed by flat surfaces.

[0057] Figure 18 is an explanatory diagram of a third modified example of a support leg 13 in which the fitting projection 15 is formed in this shape. As shown in the figure, the fitting projection 15 "K", fitting projection 15 "M", and fitting projection 15 "N" all have a shape that tapers toward the central axis CL of the support leg 13, and both sides of the tapered shape are formed by flat surfaces. In this way, when the fitting projection 15 is fitted into any of the fitting recesses 14d of another support leg 13, the flat surfaces on both sides of the tapered fitting projection 15 will face the flat surfaces of the fitting projections 15 that form the fitting recess 14d.

[0058] For example, in the fitting projection 15 "K" in Figure 18, planes Kp1 and Kp2 are formed on both sides of the tapering portion. When this fitting projection 15 "K" is fitted into the fitting recess 14d between the fitting projection 15 "M" and fitting projection 15 "N" of another support leg 13, the plane Kp1 of fitting projection 15 "K" faces the plane Np1 of fitting projection 15 "N", and the plane Kp2 of fitting projection 15 "K" faces the plane Mp2 of fitting projection 15 "M". Furthermore, when the fitting projection 15 "K" is fitted into the fitting recess 14d between the fitting projection 15 "K" and fitting projection 15 "N" of another support leg 13, the plane Kp1 of the fitting projection 15 "K" faces the plane Kp1 of the fitting projection 15 "K" of the other support leg 13, and the plane Kp2 of the fitting projection 15 "K" faces the plane Np2 of the fitting projection 15 "N" of the other support leg 13. In this way, the planes of the fitting projection 15 and the fitting projection 15 of the other support leg 13 always face each other. Therefore, even if there is some misalignment when stacking structural members 10 on top of each other and the fitting projections 15 interfere with each other, the interference will occur on their planes, thus preventing damage to the fitting projection 15.

[0059] In addition, in the support leg 13 of the third modified example described above, the positional relationship between the planes that form the tapering shape between the multiple fitting protrusions 15 may satisfy the following conditions. For the sake of explanation, below, of the planes on both sides that form the tapering shape of the fitting protrusion 15, the plane on the left side toward the central axis CL of the support leg 13 from the fitting protrusion 15 will be called the "left plane," and the plane on the right side toward the central axis CL will be called the "right plane." For example, in the fitting protrusion 15 "M" in Figure 18, plane Mp1 is the left plane, and plane Mp2 is the right plane.

[0060] Figure 19 is an explanatory diagram showing the positional relationship between planes that form a tapering shape between fitting projections 15 formed on the support leg 13 of the third modified example. First, referring to Figure 19(a), the positional relationship that the left plane of a fitting projection 15 should satisfy with respect to the planes of other fitting projections 15 will be explained. It is desirable that the left plane of a fitting projection 15 lies on the same plane as the right plane of a fitting projection 15 located to the right of the fitting projection 15 toward the central axis CL, and that this plane is offset by a predetermined amount toward the fitting projection 15 toward the central axis CL. In the example shown in Figure 19(a), it is desirable that the left plane Mp1 of fitting projection 15 "M" lies on the same plane as the right plane Np2 of fitting projection 15 "N", and that the left plane Mp1 (and the right plane Np2) are offset by a predetermined amount toward the fitting projection 15 "M" toward the central axis CL. The same applies to the left-side plane Kp1 of the mating projection 15 "K" and the left-side plane Np1 of the mating projection 15 "N".

[0061] Next, referring to Figure 19(b), the positional relationship that the right-side plane of a fitting projection 15 should satisfy with respect to the planes of other fitting projections 15 will be explained. It is desirable that the right-side plane of a fitting projection 15 lies on the same plane as the left-side plane of a fitting projection 15 located to the left of the fitting projection 15 toward the central axis CL, and that this plane is offset by a predetermined amount toward the fitting projection 15 from the central axis CL. In the example shown in Figure 19(b), it is desirable that the right-side plane Mp2 of fitting projection 15 "M" lies on the same plane as the left-side plane Kp1 of fitting projection 15 "K", and that the right-side plane Mp2 (and the left-side plane Kp1) are offset by a predetermined amount toward the fitting projection 15 "M" from the central axis CL. The same applies to the right-side plane Kp2 of fitting projection 15 "K" and the right-side plane Np2 of fitting projection 15 "N".

[0062] If the fitting projection 15 at the tip of the support leg 13 satisfies the above-described positional relationship, then when multiple structural members 10 are stacked, the side surface of the lower fitting projection 15 and the side surface of the upper fitting projection 15 will always face each other in a plane, and with a gap of twice a predetermined amount between them. Therefore, even if there is some misalignment when stacking structural members 10 on top of each other, it is possible to reliably prevent the fitting projections 15 from interfering with each other and causing damage.

[0063] Although the structural member 10 for a water storage tank in this embodiment and various modified examples have been described above, the present invention is not limited to the above embodiment and modified examples, and can be implemented in various forms without departing from the spirit of the invention. [Explanation of Symbols]

[0064] 1...Laminated structure, 10...Structural member, 11...Unit unit, 12...Base, 12a...plate-shaped member, 12b...rib, 12c...opening, 13...support leg, 14...Element member, 14a...Bottom surface, 14b...Side surface, 14c...Center side, 14d...Matching recess, 14s...Side edge, 15...Matching protrusion, 15a… When the mating surfaces are 15a and 15b… outer surfaces.

Claims

1. A structural member for a water storage tank, comprising a base and support legs erected from the underside of the base to support the base, and arranged in multiple stacked configurations to form the water storage space of the water storage tank, The support leg has an outer peripheral surface, The cross-section is a U-shaped trough, and multiple element members erected from the base are connected at their side ends with the open side of the trough facing inward. The element member has a bottom surface width that narrows from the base to the tip, and at the tip, the bottom surface width of the bottom surface and the side surface width of the bottom surface are substantially the same. The outer surface of the support leg is formed by six to ten of the element members. A structural member for a water storage tank characterized by the following features.

2. A structural member for a water storage tank, comprising a base and support legs erected from the underside of the base to support the base, and arranged in multiple stacked configurations to form the water storage space of the water storage tank, The support leg has an outer peripheral surface, The cross-section is a U-shaped trough, and multiple element members erected from the base are connected at their side ends with the open side of the trough facing inward. The element member has a bottom surface width that narrows from the base to the tip, and at the tip, the bottom surface width of the bottom is one to two times the width of the side surface of the bottom. The outer surface of the support leg is formed by six of the element members. A structural member for a water storage tank characterized by the following features.

3. A structural member for a water storage tank, comprising a base and support legs erected from the underside of the base to support the base, and arranged in multiple stacked configurations to form the water storage space of the water storage tank, The support leg has an outer peripheral surface, The cross-section is a U-shaped trough, and multiple element members erected from the base are connected at their side ends with the open side of the trough facing inward. The element member has a bottom surface width that narrows from the base to the tip, and at the tip, the bottom surface width of the bottom is 1 to 1.5 times the width of the side surface of the bottom. The outer surface of the support leg is formed by eight of the element members. A structural member for a water storage tank characterized by the following features.

Images