Structural components for water storage tanks

Abstract

To provide a structural member for a water storage tank capable of withstanding a larger load without thickening supporting legs. [Solution] The outer peripheral side of a support leg that bears the load of a structural member for a water storage tank is shaped to have a plurality of element members connected together. The element members have a U-shaped trough cross section, and the width of the bottom of the trough narrows from the base to the tip. The outer peripheral side of the support leg is shaped such that the side ends of these element members are connected together with the open side of the trough facing inward. Furthermore, the width of the bottom of the trough shape at the tip is in the range of 1 to 2 times the width of the side of the trough shape, and the outer peripheral side of the support leg is shaped using a number of such element members in the range of 6 to 10.

Description

[Technical Field]

[0001] The present invention relates to a structural member for a water storage tank that comprises a base and support legs that stand upright from the back surface of the base and support the base, and that is arranged in a stacked state to form a water storage space for the water storage tank. [Background technology]

[0002] In residential areas with large populations, it is common for most of the ground to be paved with asphalt or other materials. When the ground is paved, it becomes difficult for rainwater to seep into the ground, making urban flooding and other flooding more likely to occur. One known solution to this problem is to install underground water storage tanks. If a large amount of rainwater can be stored in a water storage tank, it can be gradually allowed to seep into the ground or gradually released into rivers, making it possible to prevent urban flooding.

[0003] One known technique for easily installing a water storage tank underground is to form a water storage tank by stacking multiple structural members (see, for example, Patent Document 1). The structural members include a rectangular base and multiple support legs that stand upright from the underside of the base and support the base. The water storage tank can be easily installed underground as follows: First, a hole is dug in the ground to form a recess, and the bottom of the recess is leveled and leveled, and then multiple structural members are placed in a flat pattern. Note that, at this time, the structural members may be placed in their original orientation (i.e., with the base on top and the support legs on the bottom), but if the structural members are placed upside down (with the base on the bottom and the support legs on the top), the multiple structural members can be easily placed on the bottom of the recess.

[0004] Once multiple structural members are placed on a flat surface, multiple structural members are placed on top of them in a flat surface. The structural members placed on top of the first structural member may be placed upside down, or they may be placed and mounted in their original orientation. In this case, the structural members are mounted with the tips of the support legs that extend upward from the base of the lower structural member butting against the tips of the support legs that extend downward from the base of the upper structural member. By stacking multiple structural members in this way, a large laminated structure made of multiple structural members can be formed underground.

[0005] A large space supported by multiple support legs is formed inside the laminated structure formed in this way, and by using this space as a water storage space, a large water storage tank can be easily installed underground. In addition, by covering the top surface of the laminated structure with soil or paving, the ground in which the water storage tank is buried can be used as a garden, parking lot, etc. Using the ground above the water storage tank in this way would apply a large load to the laminated structure, but since there are many support legs inside the laminated structure, the load can be distributed and supported by these support legs. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5006072 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in recent years, there has been a demand to install water storage tanks deeper underground or to install heavier structures on the ground above the water storage tank, which has led to a need to increase the load that the support legs can withstand. Although it is possible to withstand a greater load by making the support legs thicker, making the support legs thicker reduces the water storage space inside the laminated structure, which is undesirable because it reduces the capacity of the water storage tank.

[0008] This invention has been made to solve the above-mentioned problems associated with conventional structural members for water storage tanks, and aims to provide a structural member for water storage tanks that can withstand greater loads without making the support legs thicker. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the first structural member for a 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 back surface of the base to support the base, the structural member being arranged in a stacked state to form a water storage space for the water storage tank, The support leg has an outer peripheral side surface, A plurality of element members having a U-shaped trough-like cross section and standing on the base are connected at their side ends with the open side of the trough-like shape facing inward, The element part The material is , the gutter-shaped bottom The width of the tip narrows from the base to the tip, and at the tip, The gutter-shaped The aforementioned bottom Width and ,before Note: Groove shape side The width of the The support The legs , 6 bottles , or 8 pieces, or Formed by the ten element members And, Every other element member among the plurality of element members has a fitting protrusion formed by extending a tip side thereof, The cross-sectional shape of the fitting protrusion is a shape surrounded by the bottom surface forming the trough shape, the two side surfaces on both sides of the bottom surface, and both side planes extending from each of the two side surfaces and tapering inward. It is characterized by:

[0010] In the first structural member for a water storage tank of the present invention, the outer peripheral side surface of the support leg has a shape in which a plurality of element members are connected. The cross section U-shaped Type It is a trough-shaped component that stands upright on a base and extends from the base to the tip. bottomThe outer peripheral side of the support leg is formed by connecting the side ends of the element members with the open side of the trough facing inward. The element members that form the support leg have substantially the same dimensions as the width of the bottom of the trough at the tip, and the outer peripheral side of the support leg is formed by six such element members. 8 or 8 The shape is formed using 10 pieces. Furthermore, the element members have mating convex portions formed by extending the tip side of every other element member, and the cross-sectional shape of the mating convex portion is surrounded by a bottom surface that forms a gutter shape, two side surfaces on either side of the bottom surface, and two flat surfaces on both sides that extend from each of the two side surfaces and taper inward.

[0011] The detailed reason will be explained later, but in order to increase the strength of the support legs and the load capacity of the structural members for the water storage tank, it is considered most effective to increase the strength of the tip of the support legs. ,gutter Shape element The gutter It is effective to connect the side ends of the element members with the open side surfaces facing inward, and in particular, the shape of the tip portions of the element members is a trough shape. bottom Width and side It is considered effective to use element members whose width is substantially the same as that of the support leg. However, if you want to maintain the thickness of the support leg, the more element members that make up one support leg, the smaller the cross section of each element member must be. It is also known that if the cross section of an element member is too small or too large, the effect of increasing the strength of the support leg cannot be obtained. Therefore, the outer side of the support leg is made 6 8 or 8 10 Book The shapes formed using the element members include: Furthermore, the tip end side of every other element member is extended to form a fitting convex portion, and the cross-sectional shape of the fitting convex portion is a shape surrounded by a bottom surface forming a trough shape, two side surfaces on both sides of the bottom surface, and both side planes extending from each of the two side surfaces and tapering inward. By doing so, it is possible to increase the strength of the tip portion of the support leg, thereby making it possible to provide a structural member for a water storage tank that can withstand a larger load by increasing the strength of the support leg without making the support leg thicker.

[0012] In order to solve the above-mentioned problems, the second structural member for a 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 back surface of the base to support the base, the structural member being arranged in a stacked state to form a water storage space for the water storage tank, The support leg has an outer peripheral side surface, A plurality of element members having a U-shaped trough cross section are erected from the base, and the side ends of the element members are connected to each other with the open side of the trough shape facing inward, The element part The material is , the gutter-shaped bottom The width of the tip narrows from the base to the tip, and at the tip, The gutter-shaped The aforementioned bottom The width of ,before Note: Groove shape side The dimensions are 1 to 2 times the width of the The support The legs , formed by six of the element members And, Every other element member among the plurality of element members has a fitting protrusion formed by extending a tip side thereof, The cross-sectional shape of the fitting protrusion is a shape surrounded by the bottom surface forming the trough shape, the two side surfaces on both sides of the bottom surface, and both side planes extending from each of the two side surfaces and tapering inward. It is characterized by:

[0013] As will be described in detail later, the element members forming the support legs are , ahead Gutter shape at the end side For the width of the gutter shape bottom It has been found that the longer the width of the support leg, the smaller the effect of increasing the strength of the tip of the support leg. Also, it has been found that the relationship between the number of element members that make up the support leg and the effect of increasing the strength of the tip of the support leg is greatest when there are six element members. Therefore, when there are six element members, the trough-shaped part at the tip bottom The width of side Even when using element members that are one to two times the width of the tank, the strength of the tip of the support leg can be increased. 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] 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: A structural member for a water storage tank, comprising a base and support legs erected from the back surface of the base to support the base, the structural member being arranged in a stacked state to form a water storage space for the water storage tank, The support leg has an outer peripheral side surface, A plurality of element members having a U-shaped trough-like cross section and standing on the base are connected at their side ends with the open side of the trough-like shape facing inward, The element part The material is , the gutter-shaped bottom The width of the tip narrows from the base to the tip, and at the tip, The gutter-shaped The aforementioned bottom The width of ,before Note: Groove shape side The dimensions are 1 to 1.5 times the width of the The support The legs , formed by the eight element members And, Every other element member among the plurality of element members has a fitting protrusion formed by extending a tip side thereof, The cross-sectional shape of the fitting protrusion is a shape surrounded by the bottom surface forming the trough shape, the two side surfaces on both sides of the bottom surface, and both side planes extending from each of the two side surfaces and tapering inward. It is characterized by:

[0015] As will be explained later, The relationship between the number of element members that make up the support leg and the effect of increasing the strength of the tip of the support leg is 、6 It has been found that the effect of eight elements is the next greatest after eight. Therefore, when the number of element members is eight, the trough-shaped bottom The width of side Even when using element members that are 1 to 1.5 times the width of the tank, the strength of the tip of the support leg can be increased, and 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 the drawings]

[0016] [Figure 1]1 is a perspective view showing the overall shape of a structural member 10 for a water storage tank according to the present embodiment. [Figure 2] FIG. 2 is a perspective view showing the detailed shape of a unit 11 that forms the structural member 10 of this embodiment. [Figure 3] 1 is an explanatory diagram showing how structural members 10 of this embodiment are stacked to form a laminated structure 1. FIG. [Figure 4] FIG. 1 is an explanatory diagram showing a state in which a plurality of structural members 10 are stacked and stored. [Figure 5] FIG. 2 is a perspective view showing the outer shape of a support leg 13 employed in the structural member 10 of this embodiment. [Figure 6] 1A and 1B are explanatory diagrams showing the cross-sectional shape of the support leg 13 taken at three locations near the tip, the middle, and the base of the support leg 13. FIG. [Figure 7] 10 is an explanatory diagram showing the shape of a support leg 93 of a conventional unit 91. FIG. [Figure 8] 10 is an explanatory diagram showing how a conventional support leg 93 is crushed and deformed. FIG. [Figure 9] 10 is an explanatory diagram showing the reinforcement position of the support leg 93 that is thought to be most effective in suppressing crushing deformation in a conventional support leg 93. FIG. [Figure 10] 10 is an explanatory diagram for explaining why deformation at the tip portion of a conventional support leg 93 is thought to cause crushing deformation. [Figure 11] 3 is an explanatory diagram showing the shape of an element member 14 that forms a support leg 13 of the present embodiment. FIG. [Figure 12] FIG. 10 is an explanatory diagram showing that there is an allowable range for the number of element members 14 that can be used to form one support leg 13. [Figure 13] FIG. 10 is an explanatory diagram of an element member 14 of a first modified example. [Figure 14] 10 is an explanatory diagram of another aspect of the element member 14 of the first modified example. FIG. [Figure 15] 10 is an explanatory diagram of a support leg 13 of a second modified example. FIG. [Figure 16] 10 is an explanatory diagram showing the reason why the strength of the support leg 13 of the second modified example is increased. FIG. [Figure 17]10 is an explanatory diagram showing the correspondence between a fitting protrusion 15 formed at the tip of a support leg 13 and a fitting recess 14d of another support leg 13 with which the fitting protrusion 15 fits. FIG. [Figure 18] 10 is an explanatory diagram of the shape of a fitting protrusion 15 formed on a support leg 13 of a third modified example. FIG. [Figure 19] 10 is an explanatory diagram showing desirable conditions for the shape of the fitting protrusion 15 formed on the support leg 13 of the third modified example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] FIG. 1 is a perspective view showing the overall shape of a structural member 10 for a water storage tank according to this embodiment. The structural member 10 of this embodiment is configured with an array of four unit units 11 made of a hard resin such as PP (polypropylene), and each unit unit 11 includes a rectangular base 12 and four support legs 13 extending downward from the four corners of the back surface of the base 12. The four base units 12 are arranged in two rows, one vertically and one horizontally, in a square-shaped configuration, with the sides of adjacent base units 12 connected by bridges (not shown). This makes it relatively easy to divide one structural member 10 into two or four pieces by cutting the bridges.

[0018] 2 is a perspective view showing the detailed shape of a unit 11 that forms the structural member 10 of this embodiment. The base 12 of the unit 11 has a rectangular plate-like member 12a with plate-like ribs 12b standing upright in a lattice pattern on both sides to provide strength, and support legs 13 stand upright facing downward from the four corners of the base 12. Although not shown to avoid cluttering the drawing, a through-hole is formed in the center of the plate-like member 12a in the portion surrounded by the lattice-like ribs 12b.

[0019] The support legs 13 have a hollow structure, and at the positions where the support legs 13 connect to the base 12, the internal space of the support legs 13 opens into the plate-like member 12a of the base 12, forming large openings 12c. Since the structural member 10 of this embodiment is formed by connecting four unit units 11, the base 12 of each unit unit 11 also corresponds to the "base" of the present invention, and the support legs 13 of each unit unit 11 also correspond to the "support legs" of the present invention. The support legs 13 of this embodiment have a special shape, which will be explained in detail later. Furthermore, instead of simply having a hollow structure, the interior of the support legs 13 may have reinforcing ribs protruding from the inner wall surfaces of the support legs 13. As will be described later, the support legs 13 must have a structure (nesting structure) that allows other support legs 13 to be inserted through the openings 12c of the base 12. Simply providing reinforcing ribs protruding from the inner wall surfaces would prevent the insertion of other support legs 13, making a nesting structure impossible. However, even if a reinforcing rib is provided on the tip side of the support leg 13 from the inner wall surface, it does not interfere with the insertion of other support legs 13, so the reinforcing rib can be provided on the inner wall surface while maintaining the nesting structure.

[0020] FIG. 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 upside down on a flat surface, and multiple structural members 10 are placed on top of them in the normal orientation. The multiple structural members 10 are placed so that the tip of the support leg 13 of the lower structural member 10, which is upside down, butts against the tip of the support leg 13 of the upper structural member 10, which is in the normal orientation. The base 12 of the upside-down structural member 10 is then placed on the base 12 of the upper structural member 10, which is in the normal orientation. By repeating this process of stacking the structural members 10, a large laminated structure 1 can be formed in which multiple structural members 10 are stacked in multiple layers. If such a laminated 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 are tapered from the base to the tip and are hollow. This allows the structural member 10 to be stacked by inserting the support legs 13 of one structural member 10 inside the support legs 13 of another structural member 10. By stacking multiple structural members 10 in this manner, 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 they can be compactly combined as shown in Figure 4. As a result, even if 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 the structural member 10 of this embodiment, the support legs 13 have the following special shape to ensure sufficient strength while maintaining the nesting structure.

[0022] FIG. 5 is a perspective view showing the outer shape of the support legs 13 employed in the structural member 10 of this embodiment. FIG. 5(a) shows the unit 11 in an upside-down state. When the unit 11 is turned upside down, four support legs 13 stand upright from the four corners of the base 12. FIG. 5(b) shows an enlarged outer shape of one of the support legs 13. As shown in FIG. 5(b), the support leg 13 of this embodiment has a shape similar to a bundle of multiple element members 14. In the illustrated example, six element members 14 are bundled in a ring shape, and every other three element members 14 have mating protrusions 15 protruding from their tips. The tips of the three element members 14 that do not have mating protrusions 15 protruding are recessed relative to the mating protrusions 15, forming mating recesses 14d. Although the fitting protrusions 15 are formed integrally with the element members 14, the fitting protrusions 15 are merely appendages to the element members 14. Therefore, in the example shown in Fig. 5, the portion formed by bundling six element members 14 corresponds to the "support leg" in the present invention.

[0023] FIG. 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 FIG. 5(b)), near the middle (position BB in FIG. 5(b)), and near the base (position CC in FIG. 5(b)). FIG. 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 has a shape obtained by gathering six element members 14 together, and the cross-sectional shape of each element member 14 is U-shaped. Here, the U-shaped shape is a shape in which side edges (hereinafter referred to as side edges) extend from both sides of a central edge (hereinafter referred to as the center edge). The six element members 14 are connected by connecting the tips of the side edges of adjacent element members 14 with the open ends of the U-shape facing inward. Furthermore, near the tip of the support leg 13, the length Lc of the center edge and the length Ls of the side edges are approximately the same.

[0024] In actual support legs 13, the connection portion between the center edge and the side edge that form the U-shape is formed in an arc shape. In addition, the connection portion between the side edge and the side edge of an adjacent U-shape is also formed in an arc shape. For this reason, it may be difficult to determine the length Lc of the center edge and the length Ls of the side edge. In such cases, however, it is possible to determine the length Lc of the center edge and the length Ls of the side edge by assuming a case where the center edge and the side edge are directly connected (without an arc-shaped portion) and further assuming a case where the side edge and the adjacent side edge are directly connected (without an 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)). Even near the middle, the cross section of the support leg 13 has a shape in which the tips of the side edges of six U-shaped element members 14 are connected together with the open sides of the U-shape 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 tips, but the length Lc of the center edge is longer than the length of the center edge near the tips.

[0026] FIG. 6( c ) shows the cross-sectional shape of the support leg 13 near its base (position CC in FIG. 5( b )). Similar to the aforementioned areas near the tip and the middle, the cross-section of the support leg 13 near its base has a shape in which six U-shaped element members 14 are connected. Near the base of the support leg 13, the length Ls of the side edge is approximately the same as the length of the side edge near the middle, but the length Lc of the center edge is longer than the length of the center edge near the middle. The reason why the support leg 13 of this embodiment has such a shape is to provide the support leg 13 with sufficient strength while maintaining the nesting structure of the unit units 11. According to the inventors of the present application, by providing the support leg 13 with such a shape, the strength of the support leg 13 can be improved without increasing the thickness or the wall thickness of the support leg 13 (without resulting in an increase in weight), and the nesting structure of the unit units 11 can also be maintained. This shape was first created by the inventor of the present application by reconsidering the shape of the support leg 13 from a completely opposite perspective to that of the conventional one. As a preparation for explaining this point, we will briefly explain the shape of the support leg of a conventional structural member.

[0027] Fig. 7 is a perspective view showing the general shape of a unit 91 that forms a conventional structural member. A conventional structural member is formed by arranging such unit units 91 in two rows and columns and connecting adjacent unit units 91 together. In Fig. 7, the unit unit 91 is shown upside down so that the shape of the support legs 93 can be easily seen. As shown in the figure, the support legs 93 of the conventional unit unit 91 are erected from the four corners of a rectangular base 92. Furthermore, the shape of the support legs 93 is a prism with a rectangular cross section that becomes thinner towards the tip.

[0028] As shown in Figure 8, it is known that conventional structural members will break in the support leg 93 of the unit 91 when a load exceeding the limit is applied from above. It is also known that the mode of breakage is that the support leg 93 is deformed so that it collapses while maintaining its axial orientation. The location where this type of collapse occurs is a range (the shaded area in Figure 8(a)) slightly toward the tip near the middle of the support leg 93. It is also known that the mode of collapse deformation is such that opposing side surfaces of the support leg 93 bulge significantly outward and the remaining opposing side surfaces dent significantly inward, as shown by the dashed line in Figure 8(b). For this reason, in the past, when it became necessary to increase the strength of the support leg 93, it was common practice to increase the overall thickness of the support leg 93 or form reinforcing ribs in the range from the base to a position beyond the middle, in order to increase the strength of the portion prone to collapse (i.e., the middle of the support leg 93).

[0029] However, according to the inventors of the present application, it is not the middle portion, which is prone to crushing deformation, that really needs to have increased strength, but rather the tip portion, where crushing deformation does not occur (see FIG. 9). The reasons for this thinking are as follows. First, as described above with reference to FIG. 4, because the structural member 10 needs to have a nesting structure, the support legs 93 are hollow and formed with a tapered shape. Therefore, the cross-sectional area of ​​the support legs 93 is smallest near the tips, and the pressure due to the load is greatest near the tips, and it is also near the tips that are most susceptible to deformation. However, crushing deformation actually occurs near the middle of the support legs 93. The reason for this is that even though deformation occurs near the tips, the effects of that deformation are most likely to be felt near the middle of the support legs 93, and therefore crushing deformation is thought to occur more easily near the middle. This point will be explained in more detail below.

[0030] In many cases, the load acting on the support leg 93 is not directly applied to the side of the support leg 93, but is applied to the ceiling portion of the support leg 93 and then transmitted to the side via the ceiling portion. Therefore, as shown in FIG. 10 , the ceiling portion 93a of the support leg 93 bends slightly under the load, causing the side 93b of the support leg 93 to deform and bulge outward. Although the bulging deformation of the side 93b is slight, the effect of the deformation increases with increasing distance from the ceiling portion 93a. Therefore, the effect of deformation increases near the middle of the support leg 93, resulting in the support leg 93 being unable to withstand the load and collapsing. Based on this consideration, it should be possible to suppress the collapsing deformation of the support leg 93 by suppressing the outward bulging deformation of the side 93b at the tip of the support leg 93. As a result, it is believed possible to effectively increase the strength of the support leg 93 without increasing the overall thickness of the support leg 93 or forming reinforcing ribs in the area from the base to the middle.

[0031] As a result of further investigation based on the above-mentioned idea, the inventors of the present application came up with the idea of ​​forming support leg 13 by combining trough-shaped element members 14 as shown in Fig. 11. As shown in the figure, element member 14 has a U-shaped cross section, and the entire element member 14 is trough-shaped. In addition, the width of bottom surface 14a of the trough shape (corresponding to center side 14c of the U-shape) increases toward the bottom of element member 14, but the width of side surface 14b of the trough shape (corresponding to side side 14s of the U-shape) is approximately the same from the top to the bottom of element member 14.

[0032] Then, instead of making the shape of the support leg 13 a simple prism with a rectangular cross section like the conventional support leg 93 shown in Fig. 7, we considered making it a shape obtained by arranging multiple element members 14 with the open side of the trough shape facing inward and connecting the side surfaces 14b of adjacent element members 14 at their ends. The support leg 13 of this embodiment described above with reference to Figs. 5 and 6 was formed in this way.

[0033] In the support leg 13 of this embodiment formed in this manner, even if the bottom surface 14a of the element member 14 attempts to deform so as to bulge outward (see the dashed line in FIG. 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 toward the top, the bulging deformation of the bottom surface 14a can be almost completely suppressed near the top end of the element member 14. Furthermore, if the width of the side surfaces 14b (Ls in FIG. 11) were longer than the width of the bottom surface 14a (Lc in FIG. 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 bulge outward. However, in the element member 14 of this embodiment, the width of the bottom surface 14a (Lc in FIG. 11) near the top end is approximately the same as the width of the side surfaces 14b (Ls in FIG. 11). Therefore, deformation of the side surface 14b of the element member 14 that bulges outward can be almost completely prevented.

[0034] Furthermore, when an actual prototype of the support leg 13 was fabricated and tested based on this concept, it was found that there was a limit to the number of element members 14 that could be used to form the support leg 13, with 6 to 10 being the best number, and 6 to 8 being the best. The reason for this will be explained below.

[0035] FIG. 12 is an explanatory diagram showing the cross-sectional shape of the vicinity of the tip (position AA in FIG. 5(b)) of each support leg 13, where the number of element members 14 forming one support leg 13 is changed within a range of 4 to 12. In FIG. 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 seen from FIG. 12, the more element members 14 forming one support leg 13, the smaller the cross section of each element member 14 must be.

[0036] For example, FIG. 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 is necessary to use element members 14 with a long center side 14c length Lc and a long side side 14s length Ls. Furthermore, when the center side 14c length Lc and the side side 14s length Ls are long, the bottom surface 14a and the side surface 14b of the element member 14 are likely to bulge outward. If an attempt is made to avoid this by using element members 14 with a small cross section (i.e., element members 14 with a short center side 14c length Lc and a short side side 14s length Ls), the thickness of the support leg 13 will be thin, resulting in a decrease in the strength of the support leg 13. Therefore, when the number of element members 14 is four, it is difficult to fully utilize the idea of ​​the present inventors.

[0037] Figure 12(b) shows the case where the 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 six element members 14 are used as shown in Figure 12(b), but almost the same effect is obtained when eight element members 14 are used as shown in Figure 12(c). Furthermore, when ten element members 14 are used as shown in Figure 12(d), a certain degree of effect is seen, but it is smaller than when six or eight element members 14 are used.

[0038] The reason why the effect decreases when the number of element members 14 used is increased to ten is thought to be because the length of the side edges 14s near the upper ends of the element members 14 becomes shorter. That is, as described above with reference to FIG. 11, the side surfaces 14b of the element members 14 have the effect of suppressing deformation that would otherwise cause the bottom surfaces 14a to bulge outward. This effect is thought to be most needed near the tips of the support legs 13 (near the upper ends of the element members 14). Here, as is clear from a comparison of FIGS. 12(b) to 12(d), the length of the side edges 14s at the upper ends of the element members 14 becomes shorter as the number of element members 14 increases from six to eight and then to ten. This is thought to be because it becomes more difficult to suppress deformation that would otherwise cause the bottom surfaces 14a of the element members 14 to bulge outward.

[0039] 12(e) shows a case where the support leg 13 is formed using twelve element members 14. When twelve element members 14 are used, the length of the side edge 14s at the upper end of the element members 14 becomes shorter. This makes it difficult to suppress deformation in which the bottom surface 14a of the element members 14 tends to bulge outward, and the effect of suppressing the crushing deformation of the element members 14 cannot be obtained. From the above, in order to prevent the crushing deformation of the support leg 13 based on the idea of ​​the inventor of the present application, it is considered that the number of element members 14 used to form one support leg 13 should be preferably 6 to 8, and at most 10.

[0040] As explained in detail above, to prevent the support legs 13 from collapsing even when a large load is applied, it is important to increase the strength of the support legs 13 near their tips. To achieve this, the support legs 13 can be formed using multiple element members 14 shaped as shown in FIG. 11 . The element members 14 shown in FIG. 11 have a center side 14c with a length Lc and a side side 14s with a length Ls that are approximately the same near the top end. Using such element members 14 reliably increases the strength of the support legs 13 near their tips. Furthermore, if the number of element members 14 used to form one support leg 13 is increased, the side sides 14s near the top end of the element members 14 become shorter, making it difficult to sufficiently suppress outward bulging of the bottom surfaces 14a of the element members 14. Therefore, the number of element members 14 should be 6 to 8 (up to 10 at most).

[0041] However, the fact that there is an effect of increasing the strength of the support leg 13 even when the number of element members 14 is ten means that, as long as the length of the side edge 14s of the element member 14 is about the length Ls10 in the case where there are ten element members 14 shown in Fig. 12(d), it is possible to suppress deformation in which the bottom surface 14a of the element member 14 bulges outward. Therefore, as shown in Fig. 11, the length Lc of the center edge 14c near the upper end of the element member 14 and the length Ls of the side edge 14s do not necessarily have to be the same, and it is thought that, as long as a length about the length Ls10 of the side edge 14s in Fig. 12(d) can be ensured, the effect of increasing the strength of the support leg 13 can be obtained even if the center edge 14c is longer than the side edge 14s.

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

[0043] FIG. 14 is an explanatory diagram illustrating an example of an element member 14 according to another embodiment of the first modified example, in which the center side 14c is longer than the side sides 14s. FIG. 14(a) shows the outer shape of the element member 14 according to another embodiment of the first modified example. In the element member 14 according to the illustrated embodiment, the length Lc of the center side 14c near the upper end is set to be approximately 1.5 times the length Ls of the side sides 14s. FIG. 14(b) shows the cross-sectional shape of the support leg 13 near its tip formed using eight element members 14 according to this embodiment. As shown in the figure, the length of the side sides 14s near the tip of the support leg 13 is almost the same as the length Ls10 of the side sides 14s in FIG. 12(d). Conversely, when the support leg 13 is formed 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 made 1.5 times longer than the length Ls of the side side 14s.

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

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

[0046] First, as described above, the support legs 13 have a tapered shape, and furthermore, the outer surfaces 15b of the fitting protrusions 15 are formed by extending the tips of the element members 14. Therefore, the outer surfaces 15b of the fitting protrusions 15 are located more inward (closer to the central axis of the support legs 13) than the element members 14 before extension. However, from the perspective of maintaining the strength of the support legs 13, this is not very desirable in a structure in which multiple structural members 10 are stacked with the tips of the support legs 13 butted together.

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

[0048] As shown in Figure 16(a), when two structural members 10 are stacked, the support leg 13 of the lower structural member 10 supports the load from the upper structural member 10, but the load received by the lower support leg 13 is input from the upper support leg 13. In particular, where the upper support leg 13 has a fitting protrusion 15, the load is input from the element member 14 of the upper support leg 13 via the outer surface 15b to the fitting recess 14d of the lower support leg 13, and this load is input to the element member 14 of the lower support leg 13 via the fitting recess 14d. Also, where the upper support leg 13 has a fitting recess 14d, 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. In this way, when the outer radius R1 of the fitting recess 14d and the outer radius R2 of the abutment surface 15a of the fitting protrusion 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 will collapse or bend, making the support leg 13 more susceptible to crushing deformation.

[0049] On the other hand, FIG. 16(b) shows a case where the outer radius R1 of the fitting recess 14d is larger than the outer radius R2 of the abutment surface 15a of the fitting protrusion 15. As shown in FIG. 16(b), if the outer radius R1 of the fitting recess 14d is large, 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 passing through the upper or lower fitting recess 14d. That is, where the fitting protrusion 15 is formed in 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 the outer radius R1. Also, where the fitting recess 14d is formed in 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 of the outer radius R1. In this way, the load can be input to the element member 14 of the lower support leg 13 without going through the fitting recess 14d, so the fitting recess 14d will not collapse, and the fitting recess 14d will not bend, making the support leg 13 more susceptible to crushing deformation. As a result, the strength of the support leg 13 can be increased.

[0050] Furthermore, when forming the laminated structure 1 using the structural members 10 of the present embodiment, the first modified example, and the second modified example described above, multiple structural members 10 facing upside down are horizontally arranged, and then multiple structural members 10 facing in the original direction are placed on top of these, as described above with reference to Figure 3. At this time, the mating protrusion 15 formed at the tip of the lower support leg 13 fits into the mating recess 14d at the tip of the upper support leg 13, and the mating protrusion 15 formed at the tip of the upper support leg 13 fits into the mating recess 14d at the tip of the lower support leg 13. Therefore, the mating protrusion 15 of one support leg 13 will always fit into one of the mating recesses 14d of the other support legs 13.

[0051] Here, which of the mating recesses 14d of another support leg 13 the mating convex portion 15 of one support leg 13 will fit into 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 when turned upside down, but there are three ways in which the lower structural member 10 can be turned upside down. Then, which of the mating recesses 14d of another support leg 13 the mating convex portion 15 of one support leg 13 will fit into is determined by the way in which the upper structural member 10 matches the inverted lower structural member 10.

[0052] FIG. 17 is an explanatory diagram showing the relationship between the manner in which the lower structural member 10 is inverted upside down and the mating recesses 14d into which the mating protrusions 15 of the support legs 13 are fitted. FIG. 17(a) shows the manner in which the structural member 10 is inverted upside down. The manner in which the structural member 10 is inverted upside down includes a manner in which the structural member 10 is inverted about either the left or right edge of the structural member 10 as indicated by the hollow arrows in the figure (hereinafter referred to as a left-right inversion), a manner in which the structural member 10 is inverted about either the front or back edge of the structural member 10 as indicated by the diagonally shaded arrows in the figure (hereinafter referred to as a back (or front) inversion), and a manner in which the structural member 10 is inverted diagonally as indicated by the solid arrows in the figure. The mating recesses 14d into which the three mating protrusions 15 formed at the tips of the support legs 13 are fitted are determined depending on the manner in which the structural member 10 is inverted.

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

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

[0055] On the other hand, when the structural member 10 is inverted backward (or forward) as indicated by the hatched arrow in Figure 17(a), the other support leg 13 needs to be rotated 60 degrees (or 120 degrees, or 180 degrees) clockwise (or counterclockwise) around the central axis. Then, for example, when rotated 60 degrees clockwise, the mating protrusion 15 "M" in Figure 17(b) fits into the mating recess 14d "q" of the other support leg 13, the mating protrusion 15 "K" fits into the mating recess 14d "r" of the other support leg 13, and the mating protrusion 15 "N" fits into the mating recess 14d "p" of the other support leg 13.

[0056] In this way, the mating protrusion 15 formed at the tip of one support leg 13 fits into one of the three mating recesses 14d of another support leg 13. The mating recess 14d is formed between two mating protrusions 15. Therefore, the mating protrusion 15 may have a shape that tapers toward the central axis of the support leg 13, and both of the tapered side surfaces may be formed by flat surfaces.

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

[0058] For example, in the mating protrusion 15 "K" in Figure 18, planes Kp1 and Kp2 are formed on both sides of the tapered portion, and when this mating protrusion 15 "K" is mated with the mating recess 14d between the mating protrusion 15 "M" and mating protrusion 15 "N" of another support leg 13, plane Kp1 of the mating protrusion 15 "K" faces plane Np1 of the mating protrusion 15 "N", and plane Kp2 of the mating protrusion 15 "K" faces plane Mp2 of the mating protrusion 15 "M". Furthermore, when the mating protrusion 15 "K" is fitted into the mating recess 14d between the mating protrusion 15 "K" and the mating protrusion 15 "N" of another support leg 13, the plane Kp1 of the mating protrusion 15 "K" faces the plane Kp1 of the mating protrusion 15 "K" of the other support leg 13, and the plane Kp2 of the mating protrusion 15 "K" faces the plane Np2 of the mating protrusion 15 "N" of the other support leg 13. In this way, the flat surfaces of the mating protrusion 15 and the mating protrusion 15 of the other support leg 13 always face each other. Therefore, even if a slight misalignment occurs when stacking structural members 10 on top of each other and the mating protrusions 15 interfere with each other, the flat surfaces will interfere with each other, preventing damage to the mating protrusions 15.

[0059] Additionally, in the support leg 13 of the third modified example described above, the positional relationship between the planes forming the tapered shape between the multiple fitting protrusions 15 may satisfy the following condition. For convenience of explanation, of the planes on both sides forming the tapered shape of the fitting protrusion 15, the plane on the left side of the fitting protrusion 15 toward the central axis CL of the support leg 13 will be referred to as the "left plane," and the plane on the right side toward the central axis CL will be referred to as the "right plane." For example, for the fitting protrusion 15 "M" in FIG. 18, plane Mp1 is the left plane and plane Mp2 is the right plane.

[0060] FIG. 19 is an explanatory diagram showing the positional relationship between the planes forming the tapered shape between the fitting protrusions 15 formed on the support leg 13 of the third modified example. First, with reference to FIG. 19(a), the positional relationship that the left plane of one fitting protrusion 15 must satisfy with the planes of other fitting protrusions 15 will be described. The left plane of one fitting protrusion 15 is preferably coplanar with the right plane of the fitting protrusion 15 located to the right of the fitting protrusion 15 as viewed from the central axis CL, and the plane is preferably offset a predetermined amount from the central axis CL toward the fitting protrusion 15. In the example shown in FIG. 19(a), the left plane Mp1 of the fitting protrusion 15 "M" is preferably coplanar with the right plane Np2 of the fitting protrusion 15 "N," and the left plane Mp1 (and the right plane Np2) are preferably offset a predetermined amount from the central axis CL toward the fitting protrusion 15 "M." The same applies to the left side flat surface Kp1 of the fitting protrusion 15 "K" and the left side flat surface Np1 of the fitting protrusion 15 "N".

[0061] Next, with reference to FIG. 19(b), the positional relationship that the right plane of one fitting protrusion 15 must satisfy with the planes of other fitting protrusions 15 will be described. The right plane of one fitting protrusion 15 is preferably coplanar with the left plane of the fitting protrusion 15 on the left side of the fitting protrusion 15 as viewed from the central axis CL, and this plane is preferably offset a predetermined amount from the central axis CL toward the fitting protrusion 15. In the example shown in FIG. 19(b), the right plane Mp2 of the fitting protrusion 15 "M" is preferably coplanar with the left plane Kp1 of the fitting protrusion 15 "K," and the right plane Mp2 (and the left plane Kp1) are preferably offset a predetermined amount from the central axis CL toward the fitting protrusion 15 "M." The same applies to the right plane Kp2 of the fitting protrusion 15 "K" and the right plane Np2 of the fitting protrusion 15 "N."

[0062] If the mating protrusions 15 at the tips of the support legs 13 are arranged to satisfy the above-described positional relationship, when multiple structural members 10 are stacked, the side of the lower mating protrusion 15 and the side of the upper mating protrusion 15 will always face each other on a flat surface, with a gap twice the specified amount between them. Therefore, even if a slight misalignment occurs when stacking structural members 10 on top of each other, it is possible to reliably prevent the mating protrusions 15 from interfering with each other and causing damage.

[0063] The above describes the structural member 10 for a water storage tank in this embodiment and various modified examples, but the present invention is not limited to the above embodiments and modified examples, and can be implemented in various forms within the scope of its gist. [Explanation of symbols]

[0064] 1...Laminated structure, 10...Structural member, 11...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... fitting recess, 14s... side edge, 15... fitting protrusion, 15a: the connecting surface 15a, 15b: the outer surface.

Claims

1. A structural member for a water storage tank, comprising a base and support legs erected from the back surface of the base to support the base, the structural member being arranged in a stacked state to form a water storage space for the water storage tank, The support leg has an outer peripheral side surface, A plurality of element members having a U-shaped trough-like cross section and standing on the base are connected at their side ends with the open side of the trough-like shape facing inward, The element member has a bottom surface of the gutter shape with a width that narrows from the base side toward the tip side, and at the tip portion, the bottom surface of the gutter shape and the side surface of the gutter shape have substantially the same dimension, the support leg is formed by six, eight, or ten of the element members; Every other element member among the plurality of element members has a fitting protrusion formed by extending a tip side thereof, The cross-sectional shape of the fitting protrusion is a shape surrounded by the bottom surface forming the trough shape, the two side surfaces on both sides of the bottom surface, and both side planes extending from each of the two side surfaces and tapering inward. A structural member for a water storage tank, characterized in that:

2. A structural member for a water storage tank, comprising a base and support legs erected from the back surface of the base to support the base, the structural member being arranged in a stacked state to form a water storage space for the water storage tank, The support leg has an outer peripheral side surface, A plurality of element members having a U-shaped trough-like cross section and standing on the base are connected at their side ends with the open side of the trough-like shape facing inward, the element member has a bottom surface of the gutter shape that has a width that narrows from the base side toward the tip side, and at the tip portion, the bottom surface of the gutter shape has a width that is one to two times the width of the side surface of the gutter shape; The support leg is formed by six of the element members, Every other element member among the plurality of element members has a fitting protrusion formed by extending a tip side thereof, The cross-sectional shape of the fitting protrusion is a shape surrounded by the bottom surface forming the trough shape, the two side surfaces on both sides of the bottom surface, and both side planes extending from each of the two side surfaces and tapering inward. A structural member for a water storage tank, characterized in that:

3. A structural member for a water storage tank, comprising a base and support legs erected from the back surface of the base to support the base, the structural member being arranged in a stacked state to form a water storage space for the water storage tank, The support leg has an outer peripheral side surface, A plurality of element members having a U-shaped trough-like cross section and standing on the base are connected at their side ends with the open side of the trough-like shape facing inward, the element member has a bottom surface of the gutter shape that has a width that narrows from the base side toward the tip side, and at the tip portion, the bottom surface of the gutter shape has a width that is 1 to 1.5 times the width of the side surface of the gutter shape; The support leg is formed by eight of the element members, Every other element member among the plurality of element members has a fitting protrusion formed by extending a tip side thereof, The cross-sectional shape of the fitting protrusion is a shape surrounded by the bottom surface forming the trough shape, the two side surfaces on both sides of the bottom surface, and both side planes extending from each of the two side surfaces and tapering inward. A structural member for a water storage tank, characterized in that:

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