AU2012373593B2

AU2012373593B2 - Structural member used in rainwater storage laminated structure

Info

Publication number: AU2012373593B2
Application number: AU2012373593A
Authority: AU
Inventors: Fumio Harada; Takashi Yoshida
Original assignee: Sekisui Techno Molding Co Ltd
Current assignee: Sekisui Techno Molding Co Ltd
Priority date: 2012-03-14
Filing date: 2012-12-26
Publication date: 2017-08-24
Anticipated expiration: 2032-12-26
Also published as: CN103946465A; AU2012373593A1; WO2013136630A1; JPWO2013136630A1; KR101974240B1; CN103946465B; JP5294439B1; KR20140135238A

Abstract

Provided is a structural member for constructing a rainwater storage laminated structure by vertically stacking the structural members in a water storage tank provided beneath the ground while crossing the structural members at right angles, the structural member capable of exhibiting strong compressive strength without being deformed by loads from above and below. A structural member (1) is formed by longitudinally and laterally arranging, on a bottom plate (2), hollow truncated quadrangular pyramids (3) formed by providing front, back, right and left inclined wall plate parts (3b-3d) downward from four edges of a rectangular top plate (3a) with the lower ends thereof open downward from the lower surface of the bottom plate (2), and configured such that a V-shaped middle groove part (5) is formed so as to divide the top plate part (3a) in two in the middle of each of the hollow truncated quadrangular pyramids (3), the groove bottom lower surface of the middle groove part (5) is supported on a pair of hollow protruding parts (4, 4) provided to protrude on the top plate part (3a) of the lower-side structural member (1), and engagement recessed parts (7, 7) formed in lower end middle sections of both side inclined wall plate parts (3c, 3c) are put on both ends of the top plate part (3a) of the lower-side structural member (1).

Description

DESCRIPTION 2012373593 31 Μ 2017

Title of Invention: STRUCTURAL MEMBER FOR RAINWATER STORAGE STACK STRUCTURE 5 Technical Field [0001] The present invention relates to a structural member used for a rainwater storage stack structure in rainwater storage facilities set into the ground of places where a park, car park, road, or other facilities are built. 0 Background Art [0002] As has been known, rainwater storage facilities are built into the ground of parks, car parks, and so on, to prevent river or sewage from flooding due to heavy rains, or to utilize the collected rainwater as the need arises. 5 [0003] A rainwater storage facility is configured, for example, as described in Patent Document 1, such that a water storage tank is formed by digging down into the ground; a rainwater storage stack structure is formed inside this water storage tank with the stack structure formed by a matrix of 20 synthetic resin-made structural members having internal spaces for storage of rainwater, several layers of them being stacked upon one another; this rainwater storage stack structure is covered by a covering material such as a sheet or a paving material; and a manhole is provided adjacent the water storage 25 tank for introducing rainwater in heavy rains into the storage 1 9279172_1 (GH Matters) P97930.AU spaces to be stored. 2012373593 31 Μ 2017 [0004] The structural member forming the rainwater storage stack structure of such rainwater storage facilities, as described in the above-described Patent Document 1, includes a 5 plurality of bottomed cylindrical legs having open upper ends regularly spaced front and back and right and left inside a square frame, with the upper ends of adjacent legs integrally connected via ribs and the upper ends of the outermost legs arranged along the inner periphery of the frame being 0 integrally connected to the frame. The structural members are arranged in rows and columns inside a water storage tank, and stacked up to construct a rainwater storage stack structure, with the lower ends of the legs of upper layer structural members supported by the upper open ends of the legs of lower 5 layer structural members.

[0005] Another structural member described in Patent Document 2 includes hollow rectangular frusta with completely open bottoms closely spaced front and back and right and left, each frustum having a rectangular top plate and four slanted 20 walls extending downward and outward from the four sides of the top plates. The lower ends of adjacent rectangular frusta are integrally connected via connecting parts, and the top plates are provided with stepped portions at both ends in the lengthwise direction. 25 [0006] When the structural members with such a structure 2

9279172_1 (GH Matters) P97930.AU are arranged in rows and columns and vertically stacked upon one another in alternating orthogonal directions inside a water storage tank to build a stack structure, the bottom open ends of the rectangular frusta of upper layer structural 5 members bridge between and are supported on the stepped 2012373593 31 Μ 2017 portions at both ends of the top plates of the rectangular frusta of lower layer structural members.

Citation List Patent Literature 0 [0007]

Patent Literature 1: Japanese Patent Application Laid-Open No. 2006-342520

Patent Literature 2: Japanese Patent Application Laid-Open No. 2009-24447 5 Summary of Invention Technical Problem [0008] However, the structural member of the former type, which has a plurality of cylindrical legs aligned in rows and columns in a square frame, has the problem of bulkiness when 20 stacked up during transportation or storage. The cylindrical legs of the structural members can exhibit a sufficient load bearing capacity with respect to a large load from above when a multiplicity of the structural members are used to construct a rainwater storage facility as mentioned above. However, it 25 has problems in strength, since the thin ribs connecting the 3 9279172_1 (GH Matters) P97930.AU upper ends of these legs may crack or break if there is any variation in the applied load among adjacent cylindrical legs. 2012373593 31 Μ 2017 [0009] The structural members of the latter type, on the other hand, can be stacked up compactly by putting one upon 5 another with the hollow rectangular frusta with open bottoms oriented in the same lengthwise direction, so that the rectangular frusta of lower layer structural members fit in the rectangular frusta of upper layer structural members, which facilitates transportation and storage. When a large 0 number of the structural members are used to construct a rainwater storage facility by stacking them up vertically upon one another in alternating orthogonal directions, the lower ends of the slanted walls on both sides of the rectangular frusta of upper layer structural members are supported on the 5 stepped portions at both ends of the top plates of lower layer structural members, which are the strongest parts of the frusta, so that the structural members can stably support the load at these stepped portions. However, since the load applied to the stepped portions is supported by the stepped 20 portions of lower layer structural members via the slanted walls on both sides between the stepped portions, the slanted walls on both sides are prone to buckling deformation due to compressive force applied from above and below.

[0010] For this reason, the structural member has vertical 25 reinforcing ribs on the slanted walls on both sides of the 4

9279172_1 (GH Matters) P97930.AU rectangular frusta. However, there is a possibility that cracks may form due to stress concentration at upper and lower ends of the reinforcing ribs. Also, the rectangular frusta cannot be deeply nested in each other because of the presence 5 of reinforcing ribs and cannot be stacked up compactly during transportation or storage. An increase in the thickness of the walls of the rectangular frusta for reinforcement will lead to a decrease in the internal space for storing rainwater. 2012373593 31 Μ 2017 0 Solution to Problem [0011] To achieve the above object, the present invention provides a structural member used for a rainwater storage stack structure, which is a structural member to be arranged in rows and columns and vertically stacked upon one another in 5 alternating orthogonal directions inside a water storage tank formed by digging down into the ground for constructing the rainwater storage stack structure, the structural member including hollow rectangular frusta having a certain height arranged front and back and right and left on a flat 20 rectangular bottom plate, each rectangular frustum having a bottom completely open through the bottom plate, and including a rectangular top plate, four downwardly divergent slanted walls extending from four sides of the top plate and integrally connected at lower ends to the bottom plate, a pair 25 of hollow projections protruded in a central portion of the 5

9279172_1 (GH Matters) P97930.AU top plate and spaced apart a certain distance in a lengthwise direction of the top plate, and a center groove formed by-recessing a central portion of the top plate downward in a ν'-shape between opposite faces of the hollow projections, so 5 that when the structural members are vertically stacked upon one another in alternating orthogonal directions, bottoms of center grooves of rectangular frusta of an upper structural member are supported by hollow projections protruded on top plates of rectangular frusta of a lower structural member, and 0 that lower ends of slanted walls on both sides of the rectangular frusta of the upper structural member are supported on upper faces at both ends in a lengthwise direction of the top plates of the lower structural member. 2012373593 31 Μ 2017 [0012] One possible advantage of the present invention is that 5 the structural member may be used for a rainwater storage stack structure that may be compactly and neatly stacked up during transportation or storage and that may stably exhibits a high load bearing capacity in its entirety against load from above when stacked up to construct a rainwater storage stack 20 structure.

[0013] Preferably, the structural member may be used for a rainwater storage stack structure, slanted walls on both sides may extend downward from longer sides of the top plate of the rectangular frustum, in central portions at lower ends 25 thereof, and bottom plate parts integrally connected to the 6

9279172_1 (GH Matters) P97930.AU lower ends of the slanted walls on both sides, are respectively provided with an engaging recess to be fitted on and engaged with both ends of each top plate of the rectangular frusta of lower structural members, and a recessed 5 bottom plate part formed by protruding part of the bottom plate upward with the same cross-sectional shape as that of the engaging recess. 2012373593 31 Μ 2017 [0014] Preferably, slanted walls on both sides may extend downward from longer sides of the top plate of the rectangular 0 frustum are provided with a plurality of reinforcing grooves extending over an entire height of the rectangular frustum.

[0015] Preferably, a reinforcing rib may extend longer in a width direction of the top plate is formed to protrude downwardly from a lower end, which connects to the top plate, 5 of each of the pair of hollow projections standing on the top plate of the rectangular frustum on the opposite side from the mutually facing sides of the pair of hollow projections.

[0016] Preferably, vertically extending water passage holes may be formed in the top plates and bottoms of the 20 center grooves of the rectangular frusta, and in the bottom plate parts connecting the lower ends of adjacent rectangular frusta .

[0017] Preferably, a frame rim having a certain height may be integrally formed along four sides of the bottom plate. 25 Advantageous Effects of Invention 7

9279172_1 (GH Matters) P97930.AU

[0018] According to an embodiment, the structural member to be arranged in rows and columns and vertically stacked upon one another in alternating orthogonal directions inside a water storage tank formed by digging down into the ground for 2012373593 31 Μ 2017 5 constructing the rainwater storage stack structure, the structural member includes rectangular frusta having a certain height arranged front and back and right and left on a flat rectangular bottom plate, each rectangular frustum having a bottom completely open through the bottom plate, and being 0 configured such that lower ends of slanted walls on both sides of rectangular frusta of upper structural members are supported on upper faces at both ends in the lengthwise direction of the top plates of lower structural members. Accordingly, the structural members can be vertically stacked 5 upon one another in alternately orthogonal directions in a stable manner. The rectangular frusta can receive load from above evenly at both ends, and upper and lower structural members overlap each other in a very small area, so that a rainwater storage stack structure with a high space rate for 20 storing rainwater can be constructed.

[0019] The rectangular frusta with completely open bottoms that form the structural member further include a pair of hollow projections protruded in a central portion of the top plate and spaced apart a certain distance in the lengthwise 25 direction of the top plate, and a center groove formed by 8

9279172_1 (GH Matters) P97930.AU recessing a central portion of the top plate downward in a ν'-shape between opposite faces of the hollow projections, so that when structural members are stacked upon one another in alternating orthogonal directions, the bottoms of the center 5 grooves of rectangular frusta of upper structural members are supported by the hollow projections protruded on the top plates of rectangular frusta of lower structural members. Accordingly, outer bottom surfaces of the center grooves of rectangular frusta and lower ends of slanted walls on both 0 sides of upper structural members, are respectively supported on the top faces of the hollow projections and the upper faces at both ends of the top plates of the rectangular frusta of lower structural members, so that each rectangular frustum can entirely, evenly, and firmly receive load from above. Since 5 the opposite walls of the center grooves are continuous at 2012373593 31 Μ 2017 both ends thereof orthogonally with the slanted walls on both sides of the rectangular frusta, these center grooves and slanted walls on both sides can exhibit a high load bearing capacity to withstand vertical compressive force applied to 20 the rectangular frusta, to make buckling deformation or the like unlikely to happen, without reinforcing ribs or the like.

[0020] Accordingly, the structural member of the present invention allows for construction of a precisely built rainwater storage stack structure with good shape retention 25 properties. Also, the structural members can be neatly and 9

9279172_1 (GH Matters) P97930.AU compactly stacked upon one another with the rectangular frusta deeply nested in each other during transportation or storage.

[0021] According to the invention as set forth in claim 2, 2012373593 31 M2017 slanted walls on both sides that extend downward from longer 5 sides of the top plate of the rectangular frusta, in central portions at lower ends thereof, and bottom plate parts integrally connected to the lower ends of the slanted walls on both sides, are respectively provided with an engaging recess to be fitted on and engaged with both ends of each top plate 0 of the rectangular frusta of lower structural members, and a recessed bottom plate part formed by protruding part of the bottom plate upward with the same cross-sectional shape as that of the engaging recess. Therefore, as the structural members are vertically stacked upon one another in alternating 5 orthogonal directions, the engaging recess and the recessed bottom plate part provided in central portions at lower ends of slanted walls on both sides of the rectangular frusta and in the bottom plate parts are fitted on and engaged with both ends of the top plates of rectangular frusta of lower 20 structural members, so that a plurality of structural members can be smoothly and correctly stacked up, whereby a stable rainwater storage stack structure can be constructed, without the worry of the structural members wobbling right and left or back and forth. 25 [0022] According to the invention as set forth in claim 3, 10 9279172_1 (GH Matters) P97930.AU the slanted walls on both sides that extend downward from longer sides of the top plate of the rectangular frusta are provided with a plurality of reinforcing grooves extending over an entire height of the rectangular frusta. Accordingly, 2012373593 31 Μ 2017 5 these reinforcing grooves obviate the provision of reinforcing ribs or the like and enhance the load bearing capacity of the rectangular frusta, as well as allow the structural members to be deeply nested in each other when stacked up during transportation or storage. Furthermore, the rectangular frusta 0 can be made as thin as possible to increase the space for storing rainwater.

[0023] According to the invention as set forth in claim 4, a reinforcing rib extending longer in a width direction of the top plate is formed to protrude downwardly from a lower end, 5 which connects to the top plate, of each of the pair of hollow projections standing on the top plate of the rectangular frustum on the opposite side from the mutually facing sides of the pair of hollow projections. Accordingly, these reinforcing ribs can reliably stop downward warping of the top plate of 20 the rectangular frusta when subjected to load from above. When the structural members are stacked up to construct the rainwater storage stack structure, these reinforcing ribs do not obstruct the stacking and allow correct construction of a stable rainwater storage stack structure. 25 [0024] According to the invention as set forth in claim 5, 11

9279172_1 (GH Matters) P97930.AU vertically extending water passage holes are formed in the top plates and bottoms of the center grooves of the rectangular frusta, and in the bottom plate parts connecting the lower ends of adjacent rectangular frusta. Accordingly, rainwater 5 can be smoothly introduced into the rectangular frusta or discharged therefrom. Since the bottoms of the rectangular frusta are completely open, the frusta can entirely be filled with rainwater without air entrapment. 2012373593 31 Μ 2017 [0025] According to the invention as set forth in claim 6, 0 a frame rim having a certain height is integrally formed along four sides of the bottom plate. Thus, structural members can be readily and correctly aligned in rows and columns, with their frame rims abutted and joined together inside a water storage tank formed by digging down into the ground. A large 5 size structural member having a large number of rectangular frusta arranged in rows and columns and a frame rim along the four sides, and a small size structural member having a small number of rectangular frusta arranged in rows and columns and a frame rim along the four sides, can be combined, which 20 facilitates construction of a rainwater storage stack structure in accordance with the space of the water storage tank.

Brief Description of Drawings [0026] FIG. 1 is a perspective view of a structural 25 member. 12

9279172J (GH Matters) P97930.AU 5 2012373593 31 Μ 2017 5 0 FIG. 2 is a front view of : the same. FIG. 3 is a side view. FIG. 4 is a plan view. FIG. 5 is a longitudinal cross-sectional front view along line Xl-Xl of FIG . 4. FIG. 6 is a longitudinal cross-sectional front view along line X2-X2 of FIG . 4. FIG. 7 is a longitudinal cross-sectional front view along line X3-X3 of FIG . 4. FIG. 8 is a longitudinal cross-sectional front view along line Yl-Yl of FIG . 4. FIG. 9 is a longitudinal cross-sectional front view along line Y2-Y2 of FIG . 4. FIG. 10 is i a perspective view of structural members with different sizes. FIG. 11 is a longitudinal cross-sectional front view of structural members fitted upon one another. FIG. 12 is a longitudinal cross-sectional side view of the same. 20 FIG. 13 is a simplified cross-sectional view of a rainwater storage facility built with the structural members. FIG. 14 is a partial cross-sectional view of the rainwater storage stock structure formed by stacking up the structural members. 25 Description of Embodiments 13

9279172_1 (GH Matters) P97930.AU

[0027] Specific embodiments of the present invention will 2012373593 31 Μ 2017 now be described with reference to the drawings. The rainwater storage facility has a water storage tank 20 formed by digging down into the ground of a park, road and the like as shown in 5 FIG. 13. The bottom and four side walls of the tank are covered by a water shield sheet (not shown). A large number of structural members 1 having water storage spaces inside are aligned in rows and columns on the bottom of this water storage tank 20, and vertically stacked upon one another to 0 construct a rainwater storage stack structure 21. A spacer member 22 having a certain thickness is provided to cover the upper surface of the rainwater storage stack structure 21, and a cover layer 23 such as a protection sheet or concrete pavement is further provided. A manhole 24 is provided 5 adjacent one end of this rainwater storage facility in fluid communication with one end portion or elsewhere of the water storage tank 20 to allow for storing of rainwater in the rainwater storage stack structure 21 or drainage from the rainwater storage stack structure 21 through the manhole 24. 20 [0028] The structural member 1 that constitutes the rainwater storage stack structure 21 is a synthetic resin molded product. As shown in FIG. 1 to FIG. 9, rectangular frusta 3 having a certain height are regularly spaced apart front and back and right and left on a flat rectangular bottom 25 plate 2 having a certain thickness, with the bottoms of the 14

9279172_1 (GH Matters) P97930.AU rectangular frusta completely open downward through the bottom plate 2, and the bottom ends of adjacent rectangular frusta 3 are connected to one another via bottom plate parts 2a and 2b. While the structural member 1 shown in these drawings has a 5 square bottom plate 2 and four rectangular frusta 3 arranged front and back and right and left, it should not be limited to this example and may have two or more rows of rectangular frusta 3 arranged front and back and right and left as will be described later. 2012373593 31 Μ 2017 0 [0029] The rectangular frustum 3 is made up of a flat rectangular top plate 3a that is long in the front to back direction, which is the up and down direction in the plan view of FIG. 4, and downwardly divergent front and back slanted walls 3b and 3c and slanted walls 3c and 3c on both sides 5 extending from the front, back, right, and left side edges of the top plate 3a. A center groove 5 having a certain depth down in a central portion in the lengthwise direction of the top plate 3a extends between both slanted walls 3c and 3c on both sides to divide the top plate 3a into a front half 3a-l 20 and a rear half 3a-2. A pair of hollow projections 4 and 4 in the form of a small-diameter tube with closed upper ends or frustum with closed upper ends are spaced front to back in the lengthwise direction of the top plate 3a such as to face each other via the upper open end of the center groove 5 25 therebetween. 15

9279172_1 (GHMatters) P97930.AU

[0030] The center groove 5 extends over the entire width of the central portion of the top plate 3a between the opposite faces of the front and back hollow projections 4 and 4 that stand on the top plate 3a of the rectangular frustum 3 2012373593 31 Μ 2017 5 and deep down as far as to near the lower end of the frustum 3 in a V-shape cross section. The center groove 5 thus divides the top plate 3a into one half 3a-l and the other half 3a-2 as mentioned above, as well as divides the slanted walls 3c and 3c on both sides that extend downwards from both sides of the 0 top plate 3a that are long in the front to back direction into a front half 3c-l and a rear half 3c-2. The V-shaped center groove 5 has a bottom 5a that is flat in the horizontal direction .

[0031] One half 3c-l and the other half 3c-2 of the 5 slanted walls 3c and 3c on both sides of the rectangular frustum 3 each have two reinforcing grooves 6 with a constant width and recessed into the frustum 3 such as to have a U-shaped cross section. The reinforcing grooves extend over the entire length from the top plate 3a to the lower ends of the 20 slanted walls 3c and 3c on both sides. FIG. 8 shows central portions at the lower ends of the slanted walls 3c and 3c on both sides located below either end of groove walls facing front to back of the center groove 5. The central portions are cut away from the lower ends upward to a certain height over a 25 length slightly larger than the width in the left-right 16 9279172_1 (GH Matters) P97930.AU direction of the top plate 3a of the rectangular frustum 3, thereby forming downwardly open engaging recesses 7 and 7. 2012373593 31 Μ 2017

When a large number of structural members 1 are stacked upon one another in alternating orthogonal directions to construct 5 the rainwater storage stack structure, the engaging recesses 7 and 7 are fitted onto the front and back portions of tops of the rectangular frusta of lower structural members 1 to make engagement with and be supported on the upper faces at both ends of the top plates 3a, as shown in FIG. 14. 0 [0032] Further, as shown in FIG. 8, at the lower ends of the hollow projections 4 and 4 respectively standing on one half 3a-l and the other half 3a-2 of the top plate 3a split into two parts by the center groove 5, reinforcing ribs 8a are provided to extend downward, with their either end being 5 perpendicularly continuous with opposite inner faces at upper ends of the slanted walls 3c and 3c on both sides. At the front and back ends in the upper face of the top plate 3a are reinforcing ribs 8b and 8b that are long in the width direction of the top plate 3a. Furthermore, on the outer faces 20 at the lower ends of one half 3c-l and the other half 3c-2 of the slanted walls 3c and 3c on both sides are protruded reinforcing ribs 8c and 8c to a certain height, which are integral with the bottom plate 2 at lower ends and are tapered upwards, as shown in FIG. 5. When the structural members 1 are 25 stacked upon one another during transportation or storage, an 17 9279172_1 (GH Matters) P97930.AU upper structural member 1 is placed over a lower structural member 1 to the depth where these reinforcing ribs 8c and 8c are protruded. 2012373593 31 Μ 2017 [0033] Water passage holes 9a and 9b are formed to extend 5 through the rectangular frusta 3 in the up and down direction in one half 3a-l and the other half 3a-2 of each top plate 3a and in the top faces of each pair of hollow projections 4 and 4, respectively. A plurality of water passage holes 9c are regularly spaced in the lengthwise direction of the bottom 5a 0 of the V-shaped center groove 5 in the bottom 5a.

[0034] A plurality (four in the drawing) of the rectangular frusta 3 are arranged front and back and right and left with the longer sides of their top plates 3a being oriented along the front to back direction. The adjacent front 5 and back rectangular frusta 3 and 3, and the adjacent right and left rectangular frusta 3 and 3, are joined together via bottom plate parts 2a and 2b of the bottom plate 2, respectively, which connect both lower ends of opposite front and back slanted walls 3b and 3d of the adjacent front and 20 back rectangular frusta 3 and 3 and both lower ends of the adjacent right and left slanted walls 3c and 3c on both sides. Further, a frame rim 10 having a certain height extends from the four side edges of the bottom plate 2 upwards to surround the lower ends of the rows of the rectangular frusta arranged 25 front and back and right and left. 18

9279172_1 (GHMatters) P97930.AU

[0035] The dimension between the centers of the right and left opposite hollow projections 4 and 4 protruded on the top plates 3a and 3a of adjacent right and left rectangular frusta 3 and 3 is equal to the dimension between the centers of the 2012373593 31 Μ 2017 5 center grooves 5 and 5 of adjacent front and back rectangular frusta 3 and 3. The distance of the opening between the lower ends of the slanted walls 3c and 3c on both sides of all the rectangular frusta 3 is dimensioned such as to allow the structural member 1 to be placed over the hollow projections 4 0 and 4 on one half 3a-l and the other half 3a-2 of top plates 3a, and supported on front and back ends of top plates 3a, of rectangular frusta 3 of a structural member 1 arranged below.

[0036] The depth of the center grooves 5 in the center in the front to back direction of the rectangular frusta 3, i.e., 5 the dimension from the top face of the hollow projections 4 to the outer bottom of the center grooves 5, equals to the height dimension from the lower end of the rectangular frusta 3 to the upper surface of the top plates 3a minus the depth of the engaging recesses 7 and 7 provided at the lower ends of the 20 slanted walls 3c and 3c on both sides. When a large number of structural members 1 are vertically stacked upon one another in alternating orthogonal directions to construct the rainwater storage stack structure, the hollow projections 4 and 4 on rectangular frusta 3 of lower structural members 1 25 abut and support the outer bottoms of the center grooves 5 of 19

9279172_1 (GH Matters) P97930.AU rectangular frusta 3 of upper structural members 1. 2012373593 31 Μ 2017 [0037] The bottom plate 2 of the structural member 1 includes, as shown in FIG. 4, a bottom plate part 2a that is thin and long in the left-right direction and joining together 5 the lower ends of the opposite front and back slanted walls 3b and 3d of adjacent front and back rectangular frusta 3 and 3 arranged in series, and a center bottom plate part 2b that is thin and long in the front to back direction and joining together the lower ends of the opposite right and left slanted 0 walls 3c and 3c of adjacent right and left rectangular frusta 3 and 3, and also bottom plate parts 2c and 2c on both sides that are thin and long in the front to back direction and joining together frame parts 10b and 10b on both sides of the frame rim 10 and the lower ends of outer ones of the slanted 5 walls 3c and 3c on both sides of rectangular frusta 3 and 3 aligned front to back in series along frame parts 10b and 10b on both sides of the frame rim 10.

[0038] The bottom plate parts 2c and 2c on both sides are bottom plate parts having a certain width and joining together 20 the lower ends of the frame parts 10b and 10b on both sides of the frame rim 10 and the lower ends of the outer ones of the slanted walls 3c and 3c of rectangular frusta 3 parallel to and opposite the frame parts 10b and 10b on both sides. Water passage holes 9d extending through in the up and down 25 direction are regularly spaced along the lengthwise direction 20

9279172_1 (GH Matters) P97930.AU in the bottom plate parts 2c on both sides. On the other hand, front and back frame parts 10a and 10c of the frame rim 10 are directly and integrally connected to the lower ends of the front and back slanted walls 3b and 3d of rectangular frusta 3 5 parallel to and opposite these front and back frame parts 10a and 10c without any bottom plate parts. 2012373593 31 Μ 2017 [0039] The center bottom plate part 2b that is long in the front to back direction and has a larger constant width than the bottom plate parts 2c and 2c on both sides joins together 0 the lower ends of the inner ones of the slanted walls 3c and 3c on both sides of adjacent right and left rectangular frusta 3 and 3, i.e., the slanted walls 3c and 3c slanted toward the center of the frame rim 10, as shown in FIG. 5. Part of this center bottom plate part 2b except for the engaging recesses 7 5 and 7 that are provided at the lower ends in the center in the front to back direction of the inner slanted walls 3c and 3c opposite each other right and left on both sides of the center bottom plate part 2b is formed flat and horizontally coplanar with the bottom plate parts 2c and 2c on both sides that 20 connect to the lower ends of the frame parts 10b and 10b on both sides of the frame rim 10, as shown in FIG. 5, so as to allow stable installation on the ground or the like. Horizontally oriented oblong water passage holes 9e extend through this flat bottom plate part 2b in the up and down 25 direction, with two reinforcing ribs 8d and 8d protruded 21

9279172_1 (GHMatters) P97930.AU parallel to the lengthwise direction of the top plates 3a.

[0040] On the other hand, the bottom plate parts 2b' that 2012373593 31 Μ 2017 connect the engaging recesses 7 and 7 at the lower ends of the inner slanted walls 3c and 3c opposite each other of adjacent 5 right and left rectangular frusta 3 are protruded upward to have the same cross-sectional shape as that of the engaging recesses 7 and 7 as shown in FIG. 7 and FIG. 9. These recessed bottom plate parts 2b' are placed, together with the engaging recesses 7, over the opposite one half 3a-l and the other half 0 3a-2 of top plates 3a and 3a at the top of the adjacent front and back rectangular frusta 3 and 3 of a structural member 1 arranged below, so that the downwardly open lower faces engage with and are supported by the opposite ends of one half 3a-l and the other half 3a-2 of the top plates 3a and 3a. 5 [0041] In the lower face on both sides of these recessed bottom plate parts 2b' are protruded reinforcing ribs 8e and 8e to engage with the inner faces of the reinforcing ribs 8b and 8b protruded on the upper faces of one half 3a-l and the other half 3a-2 of top plates 3a of a structural member 1 20 arranged below, as shown in FIG. 14, when structural members 1 are stacked upon one another in alternating orthogonal directions. Central portions of these recessed bottom plate parts 2b' are recessed further upward as shown in FIG. 9 to form a space for accommodating the reinforcing ribs 8b and 8b 25 protruded upwards at both ends of top plates 3a of a lower 22

9279172_1 (GH Matters) P97930.AU rectangular frustum 3. Water passage holes 9e' are drilled in the central portions of the bottom plate parts 2b'. 2012373593 31 Μ 2017 [0042] The same applies to the bottom plate parts 2c and 2c on both sides that join together the lower ends of the 5 frame parts 10b and 10b on both sides of the frame rim 10 and the lower ends of the outer ones of the slanted walls 3c and 3c on both sides of rectangular frusta 3 and 3 aligned front to back in series along the frame parts 10b and 10b on both sides, i.e., the lower ends of the slanted walls 3c and 3c 0 facing toward both side edges of the frame rim 10. Namely, bottom plate parts 2c' between the engaging recesses 7 and 7, which are provided at the lower ends in the center in the lengthwise direction (front to back direction) of the outer slanted walls 3c and 3c of rectangular frusta 3 and 3 opposite 5 the frame parts 10b and 10b on both sides of the frame rim 10, and the lower ends of the frame parts 10b and 10b on both sides opposite these engaging recesses 7, are protruded upward to have the same cross-sectional shape as that of the engaging recesses 7 as shown in FIG. 3 and FIG. 7. These recessed 20 bottom plate parts 2c' are placed, together with the engaging recesses 7, over the ends of top plates 3a facing the frame rim 10 at the top of the rectangular frusta 3 of a structural member 1 arranged below, so that the downwardly open lower faces engage with and are supported on the upper faces at the 25 ends of the top plates 3a. Central portions of these recessed 23

9279172_1 (GH Matters) P97930.AU bottom plate parts 2c' are also recessed further upward to form a space for accommodating the reinforcing ribs 8b protruded at the ends of top plates 3a of a lower rectangular frustum 3. Water passage holes 9d' are also drilled in the 5 central portions of the bottom plate parts 2c'. 2012373593 31 Μ 2017 [0043] The bottom plate part 2a that is thin and long in the left-right direction and joining together the lower ends of the opposite front and back slanted walls 3b and 3d of adjacent front and back rectangular frusta 3 and 3, i.e., the 0 lower ends of the opposite front and back slanted walls 3b and 3e of rectangular frusta 3 and 3 aligned in series with the lengthwise direction of their top plates 3a and 3a oriented along the front to back direction, is composed of a thin and long wall member having the same height as that of the frame 5 rim 10. Vertically extending small-diameter water passage holes 9f are regularly spaced in the lengthwise direction of the bottom plate part 2a, and both ends in the lengthwise direction of the bottom plate part 2a are integrally connected to the opposite inner faces of the frame rim 10. 20 [0044] The structural members 1 configured as described above can be neatly and compactly stacked upon one another during transportation or storage as shown in FIG. 11 and FIG. 12, with the rectangular frusta 3 and 3 having bottoms completely open through the bottom plate 2 deeply nested in 25 each other. When in use, a multiplicity of structural members 24

9279172_1 (GHMatters) P97930.AU 1 are aligned in rows and columns, with opposing frame parts of frame rims 10 abutted and joined together inside the water storage tank 20 formed by digging down into the ground of a park, road, or the like, and upper layer structural members 1 5 are placed upon lower layer structural members 1 such that the lengthwise direction of the rectangular top plates 3a of the rectangular frusta 3 are oriented orthogonal to the lengthwise direction of the top plates 3a of the rectangular frusta 3 of the lower layer structural members 1, thereby building the 0 rainwater storage stack structure 21, as shown in FIG. 13.

[0045] When structural members 1 are stacked upon one 2012373593 31 Μ 2017 another such that the alternate layers are oriented at right angles to each other, as shown in FIG. 14, the lower ends of the slanted walls 3c and 3c on both sides of rectangular 5 frusta 3 of the upper structural member 1 bridge between and are supported on the upper faces of one half 3a-l and the other half 3a-2 of top plates 3a split in half by the center grooves 5 of the lower structural member 1, with the engaging recesses 7 and 7 provided at the center in the lower ends of 20 the slanted walls 3c and 3c on both sides and the recessed bottom plate parts 2b' and 2b' formed by protruding parts of the bottom plate to be continuous with the engaging recess 7 and 7 being fitted onto the ends of one half 3a-l and the other half 3a-2 of top plates 3a. At the same time, the 25 reinforcing ribs 8e and 8e protruded on both sides of the 25

9279172_1 (GH Matters) P97930.AU underside of the recessed bottom plate parts 2b' engage with the inner faces of the reinforcing ribs 8b and 8b protruded on the upper faces of one half 3a-l and the other half 3a-2 of top plates 3a of the lower structural member 1. The bottom 5 faces of the center grooves 5 of the upper structural member 1 abut and are supported on the top faces of the hollow projections 4 and 4 protruded on one half 3a-l and the other half 3a-2 of top plates 3a of the lower structural member 1. 2012373593 31 Μ 2017 [0046] The engaging recesses 7 and 7 provided at the 0 center in the lower ends of the outer ones of slanted walls 3c and 3c on both sides of rectangular frusta 3 and 3 parallel to and facing the lower ends of frame parts 10b and 10b on both sides of the frame rim 10, and the recessed bottom plate parts 2c' continuous with the engaging recesses 7, engage with and 5 are supported by the ends of the top plates 3a of rectangular frusta 3 of the lower structural member 1 located below the recessed bottom plate parts 2c'.

[0047] Thus stacking of structural members 1 is facilitated and made correctly. Since the hollow projections 4 20 and 4 protruded on one half 3a-l and the other half 3a-2 of top plates 3a of the lower structural member 1 are enclosed in the rectangular frusta 3 of the upper structural member 1 such as to conform to the inner faces at the lower ends of the slanted walls 3c and 3c on both sides of the rectangular 25 frusta 3, this engagement between the hollow projections 4 and 26

9279172_1 (GH Matters) P97930.AU 4 and the inner faces at the lower ends of the slanted walls 3c and 3c on both sides of the rectangular frusta 3 prevents displacement of the upper structural member 1 in the lengthwise direction of the top plates 3a of the lower 5 structural member 1. Moreover, the engagement between the engaging recesses 7 and 7 at the lower ends of the slanted walls 3c and 3c on both sides of the upper structural member 1 and both ends of the top plates 3a of the lower structural member 1 prevents displacement of upper structural member 1 in 0 the width direction of the top plates 3a of the lower structural member 1. Thus the rainwater storage stack structure 21 can be constructed stably with a large water storage capacity. 2012373593 31 Μ 2017 [0048] The structural member 1 exhibits a high load 5 bearing capacity with respect to load from above because of the center grooves 5 in the rectangular frusta 3, reinforcing grooves 6 with a U-shaped cross section in the slanted walls 3c and 3c on both sides of the rectangular frusta 3, and reinforcing ribs 8c protruded from the lower ends of the 20 slanted walls 3c and 3c on both sides, etc., so that buckling deformation of the four slanted walls 3b to 3d of the rectangular frusta 3 is prevented. Furthermore, the engagement between the reinforcing ribs 8e and 8e protruded on both sides on the underside of the recessed bottom plate parts 2b' and 25 the inner faces of the reinforcing ribs 8b and 8b protruded on 27

9279172J (GH Matters) P97930.AU the upper faces of one half 3a-l and the other half 3a-2 of the top plates 3a of the lower structural member 1 can prevent spreading or deformation of the divergent slanted walls 3c and 3c on both sides of lower structural members 1 when a vertical 5 load is applied to the uppermost structural member 1. The reinforcing ribs 8a and 8b can also prevent downward warping or deformation of the top plates 3a of the rectangular frusta 3. Thus a robust rainwater storage stack structure 21 can be constructed. 2012373593 31 Μ 2017 0 [0049] The structural member 1 shown in FIG. 1 to FIG. 9 is of a small size with four rectangular frusta 3, i.e., two rows of rectangular frusta arranged side by side on right and left, each row consisting of two rectangular frusta 3 and 3 arranged front and back in series, with the lengthwise 5 direction of their top plates 3a aligned along the same line. The structural member 1 according to the present invention is not limited to this and may be designed in various sizes. For example, as shown in FIG. 10, the structural member may be of a medium size 1A with two rows of rectangular frusta 3 20 arranged side by side on right and left, each row consisting of four rectangular frusta 3 in front to back series arrangement, or a medium size IB with four rows of rectangular frusta 3 arranged side by side on right and left, each row consisting of two rectangular frusta 3 and 3 in front to back 25 series arrangement, or a large size 1C with four rows of 28 9279172_1 (GH Matters) P97930.AU rectangular frusta 3 arranged side by side on right and left, each row consisting of four rectangular frusta in front to back series arrangement. 2012373593 31 Μ 2017 [0050] These large and small structural members 1, 1A to 5 1C are aligned in rows and columns in various combinations on the bottom of the water storage tank 20 such that their top plates 3a are all oriented in the same lengthwise direction, and on top of this group of structural members, another group of structural members 1, 1A to IB are stacked as the upper 0 layer such that the lengthwise direction of their top plates 3a is oriented orthogonal to that of the lower layer structural members, whereby the rainwater storage stack structure 21 is constructed.

Industrial Applicability 5 [0051] With the rectangular frusta aligned in rows and columns and stacked upon one another in alternating orthogonal directions inside a water storage tank set into the ground of places where a park, car park, road, or other facilities are built, a stack structure having excellent load bearing 20 capacity with respect to load from above can be formed, which allows construction of rainwater storage facilities capable of storing water under the ground of a park, car park, road, or other facilities.

[0052] In the claims which follow and in the preceding 25 description of the invention, except where the context 29

9279172_1 (GH Matters) P97930.AU requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to 5 preclude the presence or addition of further features in various embodiments of the invention. 2012373593 31 Μ 2017

Reference Signs List [0053] 0 1 Structural member 2 Bottom plate 3 Rectangular frusta 3a Top plate 3b to 3d Slanted wall 5 4 Hollow projection 5 Center groove 6 Reinforcing groove 7 Engaging recess 8a to 8e Reinforcing rib 20 9a to 9e Water passage hole 10 Frame rim 20 Water storage tank 21 Rainwater storage stack 30

9279172_1 (GH Matters) P97930.AU

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A structural member used for a rainwater storage stack structure, the structural member to be arranged in rows and columns and vertically stacked upon one another in alternating orthogonal directions inside a water storage tank formed by digging down into the ground for constructing the rainwater storage stack structure, the structural member comprising rectangular frusta having a certain height arranged front and back and right and left on a flat rectangular bottom plate, each rectangular frustum having a bottom completely open through the bottom plate, the rectangular frustum including a rectangular top plate, four downwardly divergent slanted walls extending from four sides of the top plate and integrally connected at lower ends to the bottom plate, a pair of hollow projections protruded in a central portion of the top plate and spaced apart a certain distance in a lengthwise direction of the top plate, and a center groove formed by recessing a central portion of the top plate downward in a V-shape between opposite faces of the hollow projections, wherein when the structural members are vertically stacked upon one another in alternating orthogonal directions, bottoms of center grooves of rectangular frusta of an upper structural member are supported by hollow projections protruded on top plates of rectangular frusta of a lower structural member, and lower ends of slanted walls on both sides of the rectangular frusta of the upper structural member are supported on upper faces at both ends in a lengthwise direction of the top plates of the lower structural member.
2. The structural member used for a rainwater storage stack structure according to claim 1, wherein slanted walls on both sides that extend downward from longer sides of the top plate of the rectangular frustum, in central portions at lower ends thereof, and bottom plate parts integrally connected to the lower ends of the slanted walls on both sides, are respectively provided with an engaging recess to be fitted on and engaged with both ends of each top plate of the rectangular frusta of lower structural members, and a recessed bottom plate part formed by protruding part of the bottom plate upward with the same cross-sectional shape as that of the engaging recess.
3. The structural member used for a rainwater storage stack structure according to claim 1, wherein slanted walls on both sides that extend downward from longer sides of the top plate of the rectangular frustum are provided with a plurality of reinforcing grooves extending over an entire height of the rectangular frustum.
4. The structural member used for a rainwater storage stack structure according to claim 1 or 3, wherein a reinforcing rib extending longer in a width direction of the top plate is formed to protrude downwardly from a lower end, which connects to the top plate, of each of the pair of hollow projections standing on the top plate of the rectangular frustum on the opposite side from the mutually facing sides of the pair of hollow projections.
5. The structural member used for a rainwater storage stack structure according to claim 1 or 2, wherein vertically extending water passage holes are formed in the top plates and bottoms of the center grooves of the rectangular frusta, and in the bottom plate parts connecting the lower ends of adjacent rectangular frusta.
6. The structural member used for a rainwater storage stack structure according to claim 1, wherein a frame rim having a certain height is integrally formed along four sides of the bottom plate.