Earthquake-damping rack

Abstract

A plurality of column members 6a, 6b of a rack are joined with an earthquake-damping joint 21. The earthquake-damping joint 24 comprises a deformation portion 24, which is narrower so as to gain increased plastic formability, and a pair of fixing portions 26, which are strengthened with increased thickness, to join an upper joint section 20a and a lower joint section 20b with a plurality of bolts 28 or the like. Said deformation portion 24 is deformed by the horizontal stress applied in the direction perpendicular to the longitudinal direction of the rack and the upper column member 6a moves upwardly, absorbing the vibration energy. Said fixing portions 26 are strengthened by increased thickness so that the bolts 28 do not yield to the shock.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to an earthquake-damping rack mainly used in an automated warehouse.

BACKGROUND OF THE INVENTION

[0002] Racks used in automated warehouses need to be earthquake-resistant. The higher they become, the higher level of earthquake-resistance is required. When columns are strengthened as required by the need to be earthquake-resistant, the thickness of the columns tends to increase substantially.

[0003] Thus, it is an object of the present invention to gain improved earthquake-resistance by damping the earthquake effects with joints which absorb relatively large earthquake vibration energy.

[0004] It is also an object of the present invention to prevent the plastic deformation of the fixing portion connecting the upper joint and the lower joint.

[0005] Further, it is also aimed at preventing the deformation of the deformation portion of the joint at the time of weak earthquakes.

[0006] Still further, the additional improvement of the present invention is aimed at making sure that only the deformation portion of the joint can be deformed.

[0007] Still further, the additional improvement of the present invention is to provide an earthquake-damping rack that is suitable for the use in an automated warehouse.

[0008] In addition, it is also an object of the present invention to decrease the thickness of the columns by alleviating horizontal stress generated at the time of earthquakes.

SUMMARY OF THE INVENTION

[0009] The present invention is an earthquake-damping rack provided with a plurality of columns, each column composed of an upper column member and a lower column member combined by a joint which comprises an upper joint and a lower joint. At least one of the upper joint and the lower joint has a deformation portion that allows the upward movement of the upper column member through deformation. The earthquake-damping rack of the present invention is also characterized in that a plurality of fixing portions that are stronger than the deformation portion are provided.

[0010] It is preferable that the upper joint and the lower joint are superposed, and the deformation portion are made thinner or narrower than the fixing portions.

[0011] It is also preferable that the earthquake-damping rack is rectangular, and the length along the longitudinal direction is substantially longer than the length along the depth direction, and that the deformation of the deformation portion of said joint is capable of damping the vibration caused by the horizontal stress working in the direction perpendicular to the longitudinal direction.

[0012] It is also preferable to superpose the upper joint and the lower joint, and to reduce the strength of the deformation portion compared with the fixing portions by making grooves or holes in the deformation portion.

[0013] Preferably, the upper joint and the lower joint are superposed, and ribs are used in said fixing portions.

[0014] The column is divided into two portions at a position lower than the middle of the whole height of the column, and the upper portion and the lower portion are joined with the joint that allows upwardly movement of the upper column member.

[0015] In the case of earthquakes and the like, when upwardly tensile stress is applied to the upper column member, the deformation portion is deformed, allowing the upwardly movement of the upper column member. This absorbs the vibration energy, and in other words damps vibration. In addition, the fixing portion combining the upper joint and the lower joint is formed outside the deformation portion, and is stronger than the deformation portion, so that even if the deformation portion is deformed, the fixing portion does not deform, serving to prevent the upper and lower column members from being disconnected. This results in increased earthquake-resistance realized without increasing the thickness of the columns. The target level of the earthquake-resistance is aimed at a very strong earthquake that might occur once or never during the life of the rack. Thus, it is preferable to design the rack so that the deformation portion does not deform in an earthquake of such a strength that might occur several times during the life. In this way, it is possible to prevent the collapse of column members and the fall-out of the rack even in an unprecedented level of earthquake without increasing the weight of the rack.

[0016] In another aspect of the present invention, the deformation portion is made thinner or narrower than the fixing portion. In this way the strength of the deformation portion is reduced compared with the fixing portion, so that only the deformation portion can be deformed without the deformation of the fixing portion.

[0017] In a third aspect of the present invention, an earthquake-damping rack that is especially suitable for an automated warehouse is provided. A rack used for an automated warehouse needs to be high-rising and also light-weighted. It is also characterized in that the length along the depth direction is substantially shorter than the length along the longitudinal direction. With the use of the earthquake-damping joint, the resistance against the horizontal stress applied in the direction perpendicular to the longitudinal direction is improved, so that the resistance against an extremely strong earthquake will be enhanced.

[0018] There are a variety of structures that are designed to reduce the relative strength of the deformation portion compared with the fixing portion. For example, grooves or holes may be made. Ribs may be used to strengthen the fixing portion.

[0019] According to another aspect of the present invention, the upper and lower column members are joined with a special joint that allows upward movement. The force applied to the earthquake-damping rack at the time of the earthquake can be dissipated by the upward movement of the upper column member. Next, as for the bending moment that is applied to the earthquake-damping rack when an earthquake occurs, there is a position where the bending moment becomes zero (known as the point of contraflexure) at a point slightly higher than the middle of the entire column. The bending moment increases toward the bottom from this point of contraflexure. Therefore, if the column is divided at a position lower than the middle of the entire column, and the joint is installed at the divided position, the earthquake-damping is more effective. As a result, the columns can be thinner because the horizontal stress generated in the event of an earthquake is alleviated.

BRIEF DESCRIPTION OF DRAWING

[0020] FIG. 1 is a perspective view of an important part of an earthquake-damping rack embodying the present invention.

[0021] FIG. 2 is a plan view of an automated warehouse employing the earthquake-damping rack embodying the present invention.

[0022] FIG. 3 is a plan view of the earthquake-damping joint employed in the embodiment.

[0023] FIG. 4 is a side view of the earthquake-damping joint of the embodiment.

[0024] FIG. 5 shows how the vibration is absorbed by deformation of the earthquake-damping joints. The left drawing shows the state after the deformation, and the drawing to the right shows the state before the deformation.

[0025] FIG. 6 is a drawing showing how the earthquake force is applied to the earthquake-damping rack in the direction perpendicular to the longitudinal direction, and how the vibration is absorbed by the earthquake-damping joint.

[0026] FIG. 7 is a plan view of the earthquake-damping joint in an alternative embodiment.

[0027] FIG. 8 is a side view of the earthquake-damping joint in the alternative embodiment.

[0028] FIG. 9 is a plan view of the earthquake-damping joint of a second alternative embodiment.

[0029] FIG. 10 is a plan view of the earthquake-damping joint of a third alternative embodiment.

[0030] FIG. 11 is a plan view of the earthquake-damping joint of a fourth alternative embodiment.

[0031] FIG. 12 is a plan view of the earthquake-damping joint of a fifth alternative embodiment.

[0032] FIG. 13 is a plan view of the earthquake-damping joint of a sixth alternative embodiment.

[0033] FIG. 14 is a plan view of the earthquake-damping joint of the sixth alternative embodiment after the deformation.

[0034] FIG. 15 is a drawing showing the relations between the upper joint, the liner and the lower joint in an embodiment wherein the liner is inserted between the upper and lower joints.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] FIG. 1 to FIG. 6 show an earthquake-damping rack embodying the present invention.

[0036] The earthquake-damping rack 2 in FIG. 1 comprises a plurality of center-columns 4 in the middle of the depth direction of the structure, a plurality of end-columns 6 at both ends of the depth direction, and a plurality of earthquake-damping joints mounted at least on each of said end-columns 6. Each of the end-columns 6 is composed of a plurality of column members, made up of square steel tubes, for example, joined with a plurality of joints, at least one of the joints being an earthquake-damping joint. 8 and 10 are beams. The beams 8 are the beams placed in the longitudinal direction and the beams 10 are placed in the direction perpendicular to the longitudinal direction. The definitions of the longitudinal direction and the depth direction are shown in FIG. 1. 12, 14 are cross ties. The rack 2 is made in what is called a truss structure. 16 is a rail laid in the longitudinal direction, and used for running a transport vehicle such as a stacker crane.

[0037] FIG. 2 shows an automated warehouse 17 having a plurality of the earthquake-damping racks 2. 3, 3 are earthquake-damping racks similar to the earthquake-damping rack 2. The length along the depth direction of the rack 3 is half that of the rack 2, having no center-columns 4. Otherwise, the structure of the rack 3 is similar to the rack 2 in that the end-columns 6 positioned at both ends of the depth direction have earthquake-damping joints. However, if the racks 3, 3 are used to serve as outer walls, the racks 3, 3 don't have to contain earthquake-damping joints in order to prevent deformation due to wind. 18 are transport vehicles such as stacker cranes. The automated warehouse 17 is composed of a plurality of the earthquake-damping racks 3 and a plurality of the earthquake-damping racks 2, which are half length along the depth direction, arranged in rows. In the automated warehouse 17, for example, if the racks 2 and the racks 3 are more than 30 meters high, and provided that the length along the longitudinal direction is extremely long compared with the length along the depth direction, it is naturally strong in the longitudinal direction, but weak against horizontal stress given in the direction perpendicular to the longitudinal direction. Thus, it is the object of the present invention to enable a higher structure that may exceed 30 meters, for example, while avoiding increased thickness of the end-columns 6.

[0038] FIG. 3 and FIG. 4 show an example of the earthquake-damping joint 21. The earthquake-damping joint 21 is composed of an upper joint 20a and a lower joint 20b, the upper and lower joints 20a, 20b having similar forms, arranged back to back. The earthquake-damping joint 21 joins the square steel tubes 6a, 6b. 22 shows a flange of the joint 21. The flange 22 may be square, for example. Each of the end-column members 6a, 6b is fixed to the flange 22 in such a method as welding. However, any type of combining methods or reinforcement methods may be used for the end-column members 6a, 6b. The flanges 22, 22 are only arranged in the positions together with the upper and lower joints 20a, 20b, and are not fixed with each other. 24 is a deformation portion aimed at absorbing vibration energy by deforming itself in the event of strong vibration. The deformation portion 24 is positioned outside the flange 22. 26 are fixing portions positioned outside the deformation portion 24, joining the upper and lower joints 20a, 20b with bolts 28 and nuts 30 or by other fixing methods such as welding. The joints 20a, 20b are made of metal with high plastic deformability such as dead soft steel. The deformation portion 24 is narrower than the flange 22 and the fixing portions 26, or thinner than the fixing portions 26 so that only the deformation portion 24 can be deformed by tensile stress. In the example described here, the deformation portion 24 is both thinner and narrower. However, it is permissible to make it either thinner or narrower. The fixing portion 26 has a base member made of dead soft steel as is used in the joint 21 and a reinforcing member made of metal stronger than the base member such as common steel combined by welding or in other method so as to make the fixing portion 26 resistant to deformation.

[0039] FIG. 5 shows an example of deformation of the deformation portion 24 due to an earthquake or the like. The drawing to the right shows the state before the tremor such as an earthquake. When upwardly tensile stress stronger than the yield point of the deformation portion 24 is applied, deformation portion 24 is deformed. The upper column member 6a is moved upwardly in respect to the lower column member 6b. As a result, there is a gap formed between the upper joint 20a and the lower joint 20b. In the case of an earthquake, when the phase of vibration changes by 180 degrees, downwardly compressive stress will follow the tensile stress. This compressive stress closes the gap of the deformation portion 24, and the state of the joint looks like the example shown by the right drawing of FIG. 5. During these movements, the energy of the earthquake or the like is absorbed. In other words, the earthquake effect is damped.

[0040] FIG. 6 shows a mechanism for preventing collapse with the use of the earthquake-damping joints 21 of the earthquake-damping rack 2. The length along the longitudinal direction of the earthquake-damping rack 2 is longer than the length along the depth direction, so that it is naturally strong against the earthquake waves in the longitudinal direction. However, the earthquake-damping rack 2 is weak against forces applied in the direction perpendicular to the longitudinal direction, because it is tall and thin. When horizontal stress is applied as shown in the white-out arrow of the FIG. 6, compressive stress is generated at a joint P between the column members 6a, 6b, on the right side of the drawing of FIG. 6, and on the left side, tensile stress is generated at a joint Q. Against this tensile stress, the deformation portion 24 is deformed so that there will be a gap in the substantially vertical direction between the two components of the deformation portion 24. When the vibration phase is changed by 180 degrees, the deformation portion 24 deforms in the area encompassing the joint P. The vibration energy is absorbed during these movements. As a result, the earthquake-resistance of the racks 2, 3 can be improved together with the increased height without increasing the thickness of the column members 6a, 6b. In addition, the rack 2 can be easily repaired by changing or repairing the joints 21 after the joints 21 have got deformed.

[0041] In the example described above, both the upper and lower joints 20a, 20b have the deformation portion 24. However, either joint may have the deformation portion 24. In the description, the effects have been described in terms of both height and earthquake-resistance. However, the present invention can be utilized in order to improve only the earthquake-resistance without increasing the height of the structures.

[0042] FIG. 7 to FIG. 12 show altered examples.

[0043] In the altered examples in FIG. 7 and FIG. 8, the earthquake-damping joint has a flange 42 for the column member to be welded to, a deformation portion 44 outside the flange 42, and a pair of fixing portions 46 which constitute in the edge outside the deformation portion 44 of the earthquake-damping joint 40. The earthquake-damping joint 40 is made of such metal as SN steel, wherein the yield point is controlled, or dead soft steel having the low yield point, which has good plastic deformability. 48 is a hole for a bolt. A pair of the earthquake-damping joints 40 are arranged back to back as in FIG. 8 and fixed with a plurality of bolts 28 and nuts 30. In the altered example as shown in FIG. 7 and FIG. 8, the deformation portion 44 is actually a kind of groove formed on a plate. The earthquake-damping joint 40 is made from a plate member with the groove 44 engraved, and a plurality of through bolt holes 48. The length of the groove 44 is the same with the length along the depth direction of the earthquake-damping joint 40, as shown vertically in FIG. 7. However, the groove 44 may be shorter than the length along the depth direction of the earthquake-damping joint 40. In the example shown in FIG. 8, the groove 44 is rectangular, but it may be circular. In short, it is only necessary to reduce the thickness of the deformation portion 44 to make it thinner than the fixing portion 46.

[0044] FIG. 9 and FIG. 10 show an example provided with holes. The earthquake-damping joint 50 in FIG. 9 has a plurality of holes 55 in the deformation portion 54 outside the flange 42, and has a plurality of bolt holes 48 at both ends thereof. Though the holes 55 are through holes in this example, dents that are not through may be usable. The holes 55 may not be limited to ovals as shown in FIG. 9, and may be circle or square.

[0045] FIG. 10 shows an earthquake-damping joint 60 comprising a plurality of holes 65 perforated in the deformation portion 64 outside the flange 42 in the center of said earthquake-damping joint 60, the deformation portion 64 having a plurality of semi-circular cuts, and the fixing portions 66 on both sides of the deformation portion 64. The fixing portions 66 have a plurality of bolt holes 48. FIG. 10 shows semi-circular cuts 65, but any other cuts such as rectangular or square cuts may be used.

[0046] FIG. 11 and FIG. 12 show an example that employs a plurality of ribs. The earthquake-damping joint 70 of FIG. 11 has a deformation portion 74 outside the flange 42, a pair of fixing portions 76 outside each of the deformation portion 74, the fixing portions 76 having a plurality of ribs 77. The number of ribs 77 may be three on each side, for example. 48 is the bolt hole. The entire earthquake-damping joint 70 is like a flat plate except for the ribs. By installing the ribs 77 in the fixing portion 76, the deformation of the fixing portion 76 is prevented, so that the deformation occurs only in the deformation portion 74. In order to make stronger contrast in the difference in strength between the fixing portion 76 and the deformation portion 74, the deformation portion 74 may have cuts, holes, or grooves as shown by dot-dash lines in FIG. 11.

[0047] The example shown in FIG. 12 is devised so that the deformation of the flange 42 and also the deformation of the fixing portion 86 are prevented. 83, 83 are ribs to reinforce the flange 42, which can also be used for bolting the column members. 84 is the deformation portion outside the flange 42. The fixing portion 86 has the rib 87 that extends along the whole depth (shown vertically in FIG. 12), thus is thicker than the deformation portion 84. The structure of the rib 87 is shown enlarged at the lower right-hand corner.

[0048] FIG. 13 and FIG. 14 show an earthquake-damping joint 90 as a still different embodiment. An upper joint 91 and a lower joint 92 are fixed to a pair of fixing portions 94 made up of a thick plate positioned on both sides of the upper and lower joints, by means of welding or in other method. 96 is the deformation portion. A plate 98 is installed at a position nearer to the center of the joint with respect to the deformation portion 96 and fixed to the plate 99 which is inside the column member with bolts or in other methods. When a large tensile stress is applied to the earthquake-damping joint 90, it deforms as shown in FIG. 14.

[0049] FIG. 15 shows an example wherein a liner 100 is installed between the upper and lower earthquake-damping joints. Although the example shown in FIG. 15 employs the upper joint 20a and lower joint 20b shown in FIG. 3, the same method can be applied to any type of joints shown in FIG. 7 to FIG. 14. FIG. 15 shows, from top to bottom, the top of the upper joint 20a, the liner 100, and the bottom of the lower joint 20b. The liner 100 is a plate member made of normal steel or the like. The liner 100 is asymmetrical in FIG. 15. The upper part of the liner 100 as shown in FIG. 15 is located outside and the lower part of the liner 100 as shown in FIG. 15 is located inside of the rack.

[0050] The liner 100 comprises a cut 102, which is a part corresponding to the deformation portion 104, and a plurality of bolt holes 106. The bolt hole 106 is made so that the bolt hole 106 is all through via the bolt hole 48 of the earthquake-damping joint. The cut 102 corresponds to the part of the flange of the earthquake-damping joint, and constitutes in a big cut facing the outside of the rack. The deformation-portion-correspon- ding part 104 is a cut made to match the deformation portion 24 of the earthquake-damping joint 21. If the earthquake-damping joint 21 is made thinner and does not have the cut, there is no need to make the deformation-portion-corresponding part 104.

[0051] In the rack 2 of FIG. 1, when horizontal stress is applied in an earthquake or the like, one column receives compressive stress while the other column has upwardly tensile stress. With the upwardly tensile stress deforms the deforming portion 24, and the upper portion of the column member moves upward. At this point, on the side where the compressive stress is applied, the horizontal stress can be dissipated more effectively if the upper portion of the column member slightly moves outwardly. If the joint 20a, 20b have a liner 100 in between, with a cut section 102 facing outwardly, the upper portion of the column member is more easily movable toward the outside. In this way the horizontal resistance against the horizontal stress is further enhanced.

[0052] The liner 100 is a plate member installed between the upper and lower joints. On both ends thereof fixing portions are made to fixed with the upper and lower earthquake-damping joints. The central part between the fixing portions serve to make the outward movement of the upper column member easier than the inward movement. Instead of making the cut 102, the area corresponding to the cut 102 may be thinner, for example.

Claims

1. An earthquake-damping rack comprising a plurality of columns, each column composed of an upper column member and a lower column member combined by a joint which comprises an upper joint and a lower joint, with at least one of the upper joint and the lower joint having a deformation portion that allows the upward movement of the upper column member through deformation, and a plurality of fixing portions that are stronger than the deformation portion.

2. An earthquake-damping rack as in claim 1, wherein the upper joint and the lower joint are superposed, the deformation portion made narrower or thinner than the fixing portion.

3. An earthquake-damping rack as in claim 1 or claim 2, wherein the length along the longitudinal direction is substantially longer than the length along the depth direction, and the deformation in the deformation portion of the joint damps the vibration caused by the horizontal stress applied in the direction perpendicular to the longitudinal direction.

4. An earthquake-damping rack as in claim 1, wherein the upper joint and lower joint are superposed, the deformation portion having grooves or holes.

5. An earthquake-damping rack as in claim 1, wherein the upper joint and the lower joint are superposed, and the fixing portions have ribs installed for the reinforcement.

6. An earthquake-damping rack characterized in that the columns are divided at a position at least lower than the middle of the whole height of the columns, and the upper column member and the lower column member are joined with the joints that allow upward movements of the upper column members.