Quake absorbing structure and quake absorbing structure construction method

Abstract

To provide a quake absorbing structure which can deal with local stress acting on a quake absorbing joint without increasing the floor height of a quake absorbing layer, and a quake absorbing structure construction method.SOLUTION: A beam-column joint 33 comprises: a lower end diaphragm 331; an upper end diaphragm 332; and a rib plate reinforcement part provided between the lower end diaphragm 331 and the upper end diaphragm 332. A steel column is joined onto the upper end diaphragm 332, steel beams are joined to the lower end diaphragm 331, the upper end diaphragm 332, and the side parts of the rib plate reinforcement part, the lower end diaphragm 331, the upper end diaphragm 332, and the rib plate reinforcement part are arranged coaxially with the steel column 31, the rib plate reinforcement part has plural rib plates 333 respectively joined to the lower end diaphragm 331 and the upper end diaphragm 332, and the plural rib plates 333 are arranged in a grid pattern in a plan view viewed from a vertical direction.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a seismic isolation structure and a construction method for the seismic isolation structure. [Background technology]

[0002] Seismic isolation structures are widely used in government facilities that serve as disaster prevention bases, regional hospitals, offices with headquarters functions, and high-rise apartment buildings, from the perspective of structural safety in the event of a major earthquake and maintaining functionality after an earthquake. In recent years, there has been a growing need for seismic isolation structures in relatively low-rise, large-scale buildings, such as logistics facilities and factories, and the number of such structures is rapidly increasing. When seismic isolation structures are adopted in low-rise, large-scale buildings, not only do they require a large number of seismic isolation devices, but the foundations and ground work required to construct the seismic isolation pits also require a large area, making the cost of seismic isolation relatively high compared to construction costs. In addition, construction work generates large amounts of waste soil, which tends to place a heavy burden on the environment due to its disposal, transportation, and disposal. As a means of taking cost and environmental considerations into account, it is extremely effective to keep the height of the base isolation layer as low as possible and reduce the amount of excavation required. From a broader perspective, the technology for designing as shallow a base isolation pit as possible can be said to be socially significant in that it lowers the barrier to seismic isolation and promotes the spread of environmentally friendly base-isolated buildings.

[0003] Recently, spherical sliding bearings such as those disclosed in Patent Document 1 have been adopted for seismic isolation of low-rise buildings with large floor plans. Spherical sliding bearings have the characteristic that their vertical support performance does not decrease when large horizontal deformation occurs, even when the device is made compact. For this reason, they tend to be preferred for lightweight buildings that require compact seismic isolation devices. However, laminated rubber bearings tend to have a decreased vertical support performance when large horizontal deformation occurs when the device is made compact. Furthermore, spherical sliding bearings have a thinner device height than laminated rubber bearings, and can compress the floor height of the seismic isolation layer, so they tend to be preferred for low-rise buildings with large floor plans. A typical example is when the upper frame is made of steel and the seismic isolation device is a spherical sliding bearing. In such cases, steel pipe columns are used as the columns of the upper frame, and concrete-filled steel pipes (CFT) are not used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-128679 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 is an example of a spherical sliding bearing. While spherical sliding bearings are more compact than laminated rubber bearings, they subject the seismic isolation device to very large local stresses at the joints between the base isolation device and the building frame. For this reason, they must be designed to withstand several times higher surface pressure in the event of a long-term vertical load. For example, when spherical sliding bearings are used in a steel-framed building, as shown in Figure 14, a base plate 81 is provided on top of the spherical sliding bearing 4, and multiple rib plates 83 are provided between the base plate 81 and the superstructure 3 (superstructure). The slider of a spherical sliding bearing is normally located on the central axis of the steel pipe column, and during an earthquake, the slider moves in response to the shaking. For this reason, rib plates are, for example, provided in a cross shape on the central axis of the steel pipe column so that they can transmit the column axial force under normal conditions, and multiple rib plates are provided in the area outside the central axis of the steel pipe column so that they can also transmit the column axial force during an earthquake. For this reason, even if the spherical sliding bearing device is made smaller, the installation of a base plate and multiple rib plates creates the problem of increasing the floor height of the seismic isolation layer.

[0006] Therefore, an object of the present invention is to provide a seismic isolation structure and a construction method for a seismic isolation structure that can accommodate local stresses acting on seismic isolation joints without increasing the floor height of the seismic isolation layer. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a seismic isolation structure comprising a lower structure, an upper structure provided above the lower structure, and a spherical sliding bearing provided between the lower structure and the upper structure, the upper structure having a column-beam joint where a steel column and a steel beam are joined, the spherical sliding bearing being connected below the column-beam joint, the column-beam joint comprising a lower end diaphragm provided at a lower end and joined to the spherical sliding bearing, an upper end diaphragm provided at an upper end, and a rib plate provided between the lower end diaphragm and the upper end diaphragm. and a rate reinforcement portion, wherein the steel column is joined onto the upper end diaphragm, the steel beam is joined to the sides of the lower end diaphragm, the upper end diaphragm and the rib plate reinforcement portion, the lower end diaphragm, the upper end diaphragm and the rib plate reinforcement portion are arranged coaxially with the steel column, and the rib plate reinforcement portion has a plurality of rib plates joined to the lower end diaphragm and the upper end diaphragm, respectively, and the plurality of rib plates are arranged in a lattice pattern when viewed in a plan view from the vertical direction.

[0008] In the present invention, a rib plate reinforcement section, in which multiple rib plates are arranged in a grid pattern, is provided at the column-beam joint, thereby increasing the strength and rigidity of the column-beam joint and enabling it to cope with local stresses acting on the seismic isolation joint. In the present invention, the lower end diaphragm provided on the spherical sliding bearing not only serves as a diaphragm provided at the lower end of the column-beam joint, but also as a base plate provided on the spherical sliding bearing to support the column-beam joint. Furthermore, in the seismic isolation structure of the present invention, multiple rib plates of the rib plate reinforcement section are provided between the lower end diaphragm and the upper end diaphragm. Therefore, the seismic isolation structure of the present invention can reduce the height of the seismic isolation joint compared to a seismic isolation structure in which a base plate is provided below the lower end diaphragm and multiple rib plates are provided between the lower end diaphragm and the base plate. In this way, the seismic isolation structure of the present invention can cope with local stresses acting on the seismic isolation joint without increasing the floor height of the seismic isolation layer.

[0009] In the seismic isolation structure of the present invention, the steel column may be a square steel pipe, and the rib plate reinforcement portion may have a square cylindrical column skin plate reinforcement portion located vertically below the skin plate of the square steel pipe, a cross-shaped reinforcement portion located inside the column skin plate reinforcement portion in a planar view and where the rib plate intersects on the axis of the steel column, and an outer peripheral reinforcement portion located outside the column skin plate reinforcement portion in a planar view.

[0010] The column skin plate reinforcement is located vertically below the skin plate of the steel column and is connected to the steel column via the upper diaphragm. This allows the column skin plate reinforcement to transmit the axial force of the steel column and bear the stress of the steel column. A cruciform reinforcement is located inside the column skin plate reinforcement, and a perimeter reinforcement is located outside it. This allows the axial force of the steel column transmitted to the column skin plate reinforcement to be transmitted from the cruciform reinforcement, column skin plate reinforcement, and perimeter reinforcement to the entire lower diaphragm and then to the spherical sliding bearing, preventing the axial force of the steel column from being transmitted locally to the spherical sliding bearing. The cruciform reinforcement, column skin plate reinforcement, and perimeter reinforcement can also bear the shear force of the column-beam joint transmitted from the steel beam.

[0011] In the seismic isolation structure of the present invention, the lower end diaphragm is designed to be larger than the steel column in a planar view from the vertical direction, and the rib plates that constitute the outer peripheral reinforcement portion may be arranged up to the edge of the lower end diaphragm.

[0012] This structure allows the axial force of the steel column to be transmitted to the entire bottom diaphragm. Even if the slider of the spherical bearing deforms horizontally and moves to the outside of the steel column in a plan view, the bearing stress received by the bottom diaphragm can be transmitted to the steel column.

[0013] In order to achieve the above object, a construction method for a seismic isolation structure according to the present invention is a construction method for a seismic isolation structure according to claim 1, wherein the plurality of rib plates are composed of a plurality of first plates whose plate surfaces face a first horizontal direction and are arranged at intervals in the first horizontal direction, and a plurality of second plates whose plate surfaces face a second horizontal direction intersecting the first horizontal direction and are arranged at intervals in the second horizontal direction, the plurality of first plates and the plurality of second plates are arranged in a lattice pattern, and the plurality of second plates are each composed of a plurality of second plate segments whose plate surfaces face the second horizontal direction and are arranged in the first horizontal direction, the second plate segments are arranged between the first plates adjacent to each other in the first horizontal direction and on the outsides of the first plates arranged at both ends of the arrangement, a first center plate of the plurality of first plates arranged at an intermediate portion of the arrangement is joined to the lower end diaphragm, and a second center plate of the second plates arranged at an intermediate portion of the arrangement, the second plate segment adjacent to the first center plate, is connected to the lower end diaphragm and the first center plate the first center plate and the second plate segment joined to the lower end diaphragm are joined to the upper end diaphragm; a first outer plate of the plurality of first plates arranged on the outside of the arrangement is joined to the lower end diaphragm and the second plate segment already joined to the lower end diaphragm; the second plate segment arranged between the first center plate and the first outer plate in the second outer plate arranged on the outside of the arrangement of the second plates is joined to the lower end diaphragm, the upper end diaphragm, the first center plate, and the first outer plate; the first outer plate is joined to the lower end diaphragm and the lower end diaphragm; the second plate segment arranged on the outside of the first outer plate in the second outer plate is joined to the lower end diaphragm and the first outer plate; the second plate segment arranged on the outside of the first outer plate in the second center plate is joined to the steel beam and joined to the first outer plate; and the steel column is joined to the upper end diaphragm.

[0014] In the present invention, the multiple rib plates can be easily joined to the lower and upper diaphragms. Because the multiple rib plates can be butt-welded to the lower diaphragm, which also serves as a base plate supporting the column-beam joint, quality can be controlled by ultrasonic testing. [Effects of the Invention]

[0015] According to the present invention, it is possible to accommodate local stress acting on seismic isolation joints without increasing the floor height of the seismic isolation layer. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a front view of a seismic isolation structure according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line BB in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line CC in FIG. [Figure 5] FIG. 4 is a cross-sectional view taken along line DD in FIG. 3. [Figure 6] FIG. [Figure 7] FIG. 4 is a schematic diagram of a rib plate reinforcing portion. [Figure 8] FIG. 1 is a diagram illustrating a construction method for a seismic isolation structure. [Figure 9] FIG. 9 is a diagram illustrating the construction method of the seismic isolation structure following FIG. 8. [Figure 10] FIG. 10 is a diagram illustrating the construction method of the seismic isolation structure, following FIG. 9. [Figure 11] 11 is a diagram illustrating the construction method of the seismic isolation structure following FIG. 10. [Figure 12] 12 is a diagram illustrating the construction method of the seismic isolation structure following FIG. 11. [Figure 13] FIG. 13 is a diagram illustrating the construction method of the seismic isolation structure following FIG. 12. [Figure 14] FIG. 1 is a front view of a conventional seismic isolation structure. DETAILED DESCRIPTION OF THE INVENTION

[0017] A seismic isolation structure and a method for constructing the seismic isolation structure according to an embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a seismic isolation structure 1 according to this embodiment includes a lower structure 2, an upper structure 3, and a spherical sliding bearing 4 provided in a seismic isolation layer 41 between the lower structure 2 and the upper structure 3. The lower structure 2 is a reinforced concrete foundation. The spherical sliding bearing 4 includes a lower sliding plate 42 provided in the lower structure 2, an upper sliding plate 43 provided in the upper structure 3, and a slider 44 provided between the lower sliding plate 42 and the upper sliding plate 43. A column-beam joint 33 is connected to the upper part of the upper sliding plate 43, where a steel column 31 and a steel beam 32 of the upper structure 3 are joined. The steel column 31 is a square steel pipe. The steel beam 32 is an H-shaped steel or an I-shaped steel.

[0018] As shown in Figures 1 to 3, steel beams 32 are joined to the column-beam joint 33 from each of two horizontal directions that are perpendicular to each other. These two horizontal directions are referred to as the X direction and the Y direction. The X direction corresponds to the first horizontal direction in the claims. The Y direction corresponds to the second horizontal direction in the claims. Steel beams 32 are joined to the column-beam joint 33 from all four sides, both in the X direction and both in the Y direction. As shown in Figures 1, 4, and 5, steel columns 31 are joined to the column-beam joint 33 from above in the vertical direction.

[0019] As shown in Figures 1, 3, and 6, the column-beam joint 33 has a lower end diaphragm 331, an upper end diaphragm 332, and a rib plate reinforcing portion 34. The rib plate reinforcing portion 34 has a plurality of rib plates 333. As shown in Figure 1, the lower end diaphragm 331 is provided at the lower end of the column-beam joint 33. A spherical sliding bearing 4 is joined below the lower end diaphragm 331. The lower end diaphragm 331 also serves as a base plate joined on top of the spherical sliding bearing 4. The upper end diaphragm 332 is provided at the upper end of the column-beam joint 33. A steel column 31 is joined on top of the upper end diaphragm 332.

[0020] As shown in FIG. 6, the lower end diaphragm 331 and the upper end diaphragm 332 are flat steel plates with square plate surfaces. The lower end diaphragm 331 has a larger plate surface than the upper end diaphragm 332. The center of the plate surface of the upper end diaphragm 332 and the center of the plate surface of the lower end diaphragm 331 are positioned on the axis of the steel column 31. A rib plate reinforcement portion 34 is disposed between the lower end diaphragm 331 and the upper end diaphragm 332. As shown in FIG. 3, the multiple rib plates 333 of the rib plate reinforcement portion 34 are arranged so that their planar shape when viewed from the vertical direction forms a lattice pattern. As shown in FIGS. 1 and 3, the longitudinal end of the lower flange 32a of the steel beam 32 is joined to the outer edge of the lower end diaphragm 331. The longitudinal end of the upper flange 32b of the steel beam 32 is joined to the outer edge of the upper end diaphragm 332.

[0021] As shown in FIG. 6 , the multiple rib plates 333 of the rib plate reinforcement portion 34 are composed of a first center plate 51, two first outer plates 52, 53, a second center plate 61, and two second outer plates 62, 63. The first center plate 51 and the two first outer plates 52, 53 are each formed in a flat plate shape and are disposed between the lower end diaphragm 331 and the upper end diaphragm 332 with their plate surfaces facing the X direction. The first center plate 51 is disposed between the two first outer plates 52, 53. That is, the first center plate 51 and the two first outer plates 52, 53 are disposed in parallel and equidistant from one side to the other in the X direction in the order of the first outer plate 52, first center plate 51, and first outer plate 53. The first center plate 51 and the two first outer plates 52, 53 correspond to the first plates in the claims.

[0022] As shown in FIGS. 3, 4, and 6, the plate surface of the first center plate 51 is rectangular. The length dimensions of the upper and lower edge portions of the first center plate 51, i.e., the length dimension in the Y direction, are the same as the length dimension in the Y direction of the lower-end diaphragm 331. As shown in FIGS. 3, 5, and 6, the two first outer plates 52, 53 have the same shape. We will explain the shape of the first outer plate 52, and will not explain the shape of the first outer plate 53. The plate surface of the first outer plate 52 has a shape in which the length dimension in the Y direction of the upper side is smaller than the length dimension in the Y direction of the lower side. The shape of the plate surface of the first outer plate 52 is rectangular at the lower side, trapezoidal at the middle portion in the vertical direction, and rectangular at the upper side that is longer in the Y direction than the lower side. The shape of the plate surface of the first outer plate 52 is symmetrical in the Y direction. The horizontal dimension of the rectangle at the lower side of the plate surface of the first outer plate 52, i.e., the dimension in the Y direction, is the same as the length dimension in the Y direction of the lower-end diaphragm 331. The horizontal dimension of the rectangle on the upper side of the plate surface of the first outer plate 52, i.e., the dimension in the Y direction, is the same as the length dimension in the Y direction of the upper end diaphragm 332. The dimension of the lower base of the trapezoidal shape at the vertical middle part of the plate surface of the first outer plate 52 is the same as the horizontal dimension of the rectangle on the lower side, i.e., the length dimension in the Y direction of the lower end diaphragm 331. The dimension of the upper base of the trapezoidal shape at the vertical middle part of the plate surface of the first outer plate 52 is the same as the horizontal dimension of the rectangle on the upper side, i.e., the length dimension in the Y direction of the upper end diaphragm 332.

[0023] The first center plate 51 and the first outer plates 52, 53 have the same vertical dimension, which is approximately the same as the distance between the lower-end diaphragm 331 and the upper-end diaphragm 332. The lower edge of the first center plate 51 is joined to approximately the center in the X direction of the upper surface 331a of the lower-end diaphragm 331. The upper edge of the first center plate 51 is joined to approximately the center in the X direction of the lower surface 332a of the upper-end diaphragm 332. The upper edge of the first outer plate 52 is joined to an edge 332b on one side in the X direction of the upper-end diaphragm 332. The lower edge of the first outer plate 52 is joined to the upper surface 331a of the lower-end diaphragm 331. The upper edge of the first outer plate 53 is joined to an edge 332c on the other side in the X direction of the upper-end diaphragm 332. The lower edge of the first outer plate 53 is joined to the upper surface 331 a of the lower end diaphragm 331 .

[0024] 2, 3, and 6, the second center plate 61 and the two second outer plates 62, 63 are each formed in a flat plate shape and are disposed between the lower end diaphragm 331 and the upper end diaphragm 332 with their plate surfaces facing the Y direction. The second center plate 61 is disposed between the second outer plate 62 and the second outer plate 63. That is, the second center plate 61 and the two second outer plates 62, 63 are disposed in parallel and at equal intervals from one side to the other in the Y direction in the order of the second outer plate 62, the second center plate 61, and the second outer plate 63. The second center plate 61 and the two second outer plates 62, 63 correspond to the second plates in the claims.

[0025] The second center plate 61 and the two second outer plates 62, 63 are each divided into four segments 611-614, 621-624, and 631-634 in the X direction. The segments 611-614, 621-624, and 631-634 correspond to the second plate segments in the claims. The four segments of the second center plate 61 are referred to as first to fourth segments 611-614 from one side to the other in the X direction. The first to fourth segments 611-614 are arranged on the same vertical plane. The four segments of the second outer plate 62 are referred to as first to fourth segments 621-624 from one side to the other in the X direction. The first to fourth segments 621-624 are arranged on the same vertical plane. The four divided bodies of the second outer plate 63 are referred to as first to fourth divided bodies 631 to 634 from one side to the other in the X direction. The first to fourth divided bodies 631 to 634 are arranged on the same vertical plane.

[0026] The shapes of the first to fourth segments 611-614 of the second center plate 61 are substantially the same as the shape of the first center plate 51 divided into four sections in the lateral direction (horizontal direction along the plate surface). The plate surfaces of the first to fourth segments 611-614 of the second center plate 61 are rectangular. The shapes of the first to fourth segments 621-624 of the second outer plate 62 are substantially the same as the shape of the first outer plate 52 divided into four sections in the lateral direction. The plate surfaces of the second segment 622 and the third segment 623 of the second outer plate 62 are rectangular. The second segment 622 and the third segment 623 of the second outer plate 62 are substantially the same as the shapes of the second segment 612 and the third segment 616 of the second center plate 61. The plate surfaces of the first segment 621 and the fourth segment 624 of the second outer plate 62 are trapezoidal. The first divided body 621 and the fourth divided body 624 of the second outer plate 62 have a smaller height dimension than the second divided body 622 and the third divided body 623. The first to fourth divided bodies 631-634 of the second outer plate 63 have the same shape as the first to fourth divided bodies 621-624 of the second outer plate 62.

[0027] The first segments 611, 621, 631 of the second center plate 61 and the second outer plates 62, 63 are disposed on one side of the first outer plate 52 in the X direction. The edges of the first segments 611, 621, 631 on the other side in the X direction are joined to a surface of the first outer plate 52 on one side in the X direction. The lower edges of the first segments 611, 621, 631 are joined to the upper surface 331a of the lower-end diaphragm 331. The fourth segments 614, 624, 634 of the second center plate 61 and the second outer plates 62, 63 are disposed on the other side of the first outer plate 53 in the X direction. The edges of the fourth segments 614, 624, 634 on one side in the X direction are joined to a surface of the first outer plate 53 on the other side in the X direction. The lower edges of the fourth divided bodies 614, 624, and 634 are joined to the upper surface 331a of the lower end diaphragm 331.

[0028] The second segments 612, 622, 632 of the second center plate 61 and the second outer plates 62, 63 are disposed between the first center plate 51 and the first outer plate 52. Edges of the second segments 612, 622, 632 on one side in the X direction are joined to a surface of the first outer plate 52 on the other side in the X direction. Edges of the second segments 612, 622, 632 on the other side in the X direction are joined to a surface of the first center plate 51 on one side in the X direction. Lower edges of the second segments 612, 622, 632 are joined to an upper surface 331a of the lower-end diaphragm 331. An upper edge of the second segment 612 of the second center plate 61 is joined to a lower surface 332a of the upper-end diaphragm 332. An upper edge portion of the second divided body 622 of the second outer plate 62 is joined to an edge portion 332d on one side in the Y direction of the upper end diaphragm 332. An upper edge portion of the second divided body 632 of the second outer plate 63 is joined to an edge portion 332e on the other side in the Y direction of the upper end diaphragm 332.

[0029] The third segments 613, 623, 633 of the second center plate 61 and the second outer plates 62, 63 are disposed between the first center plate 51 and the first outer plate 53. The edges of the third segments 613, 623, 633 on the other side in the X direction are joined to a surface of the first outer plate 53 on one side in the X direction. The edges of the third segments 613, 623, 633 on one side in the X direction are joined to a surface of the first center plate 51 on the other side in the X direction. The lower edges of the third segments 613, 623, 633 are joined to an upper surface 331a of the lower-end diaphragm 331. The upper edge of the third segment 613 of the second center plate 61 is joined to a lower surface 332a of the upper-end diaphragm 332. An upper edge portion of the third divided body 623 of the second outer plate 62 is joined to an edge portion 332d on one side in the Y direction of the upper end diaphragm 332. An upper edge portion of the third divided body 633 of the second outer plate 63 is joined to an edge portion 332e on the other side in the Y direction of the upper end diaphragm 332.

[0030] The upper flange 32b of the steel beam 32 protrudes further toward the beam-column joint 33 than the lower flange 32a and web 32c. The upper flange 32b of the steel beam 32 is joined to the edge of the upper end diaphragm 332. The lower flange 32a of the steel beam 32 is joined to the edge of the lower end diaphragm 331. The end of the web 32c of the steel beam 32 extending in the X direction is joined to the X-direction edge of the second center plate 61. The end of the web 32c of the steel beam 32 extending in the Y direction is joined to the Y-direction edge of the first center plate 51. The steel column 31 is joined onto the upper end diaphragm 332.

[0031] As shown in FIG. 7, the rib plate reinforcement portion 34 has a structure in which three plates, namely, a first center plate 51 and first outer plates 52 and 53, each with their plate surfaces facing the X direction and arranged in the X direction, and three plates, namely, a second center plate 61 and second outer plates 62 and 63, each with their plate surfaces facing the Y direction and arranged in the Y direction, are assembled in a lattice pattern.

[0032] The rib plate reinforcement portion 34 has a cross-shaped reinforcement portion 341, a column skin plate reinforcement portion 342, and an outer peripheral reinforcement portion 343. The cross-shaped reinforcement portion 341 is a cross-shaped portion formed by the Y-direction intermediate portion of the first center plate 51 and the second division 612 and third division 623 of the second center plate 61. The column skin plate reinforcement portion 342 is a square cylindrical portion surrounding the cross-shaped reinforcement portion 341, which is formed by the Y-direction intermediate portion of the first outer plate 52, the Y-direction intermediate portion of the first outer plate 53, the second division 622 of the second outer plate 62, the third division 623 of the second outer plate 62, the second division 632 of the second outer plate 63, and the third division 633 of the second outer plate 63. The cross-sectional shape of the column skin plate reinforcement portion 342 is the same as the cross-sectional shape of the skin plate of the steel column 31. The column skin plate reinforcement portion 342 is disposed vertically below the steel column 31. The column skin plate reinforcement portion 342 is joined to the steel column 31 via the upper end diaphragm 332. The outer periphery reinforcement portion 343 is a portion disposed outside the column skin plate reinforcement portion 342 formed by both end portions in the Y direction of the first center plate 51, both end portions in the Y direction of the first outer plate 52, both end portions in the Y direction of the first outer plate 53, the first division 611 and the fourth division 614 of the second center plate 61, the first division 621 and the fourth division 624 of the second outer plate 62, and the first division 631 and the fourth division 634 of the second outer plate 63.

[0033] A construction method for the column-beam joint 33 (construction method for a seismic isolation structure) will be described. The lower-end diaphragm 331 is placed on the spherical sliding bearing 4. As shown in Fig. 8, the second division 612 and the third division 613 of the first center plate 51 and the second center plate 61 are joined onto the lower-end diaphragm 331. The second division 612 and the third division 613 of the first center plate 51 and the second center plate 61 are joined together. The upper-end diaphragm 332 is joined onto the second division 612 and the third division 613 of the first center plate 51 and the second center plate 61.

[0034] As shown in Fig. 9, the first outer plate 52 is disposed on one side in the X direction of the second divided body 612 of the second center plate 61. The first outer plate 53 is disposed on the other side in the X direction of the third divided body 613 of the second center plate 61. As shown in Fig. 10, the second divided body 622 of the second outer plate 62 and the second divided body 632 of the second outer plate 63 are joined between the first center plate 51 and the first outer plate 52. The third divided body 623 of the second outer plate 62 and the third divided body 633 of the second outer plate 63 are joined between the first center plate 51 and the first outer plate 53.

[0035] As shown in Fig. 11 , the first divided body 621 of the second outer plate 62 and the first divided body 631 of the second outer plate 63 are joined to one side of the first outer plate 52 in the X direction. See Fig. 3 for the first divided body 631 of the second outer plate 63. The fourth divided body 624 of the second outer plate 62 and the fourth divided body 634 of the second outer plate 63 are joined to the other side of the first outer plate 53 in the X direction. At this time, the first outer plate 52 and the first outer plate 53 are joined to the lower end diaphragm 331 and the upper end diaphragm 332.

[0036] 12, the upper flanges 32b of the steel beams 321, 322 extending in the Y direction are joined to the beam-column joints 33 from both sides in the Y direction. The upper flanges 32b of the steel beams 32 extending in the Y direction are joined to the Y-direction edge of the upper-end diaphragm 332 and the upper edge of the first center plate 51, and the lower flanges 32a are joined to the lower-end diaphragm 331. The Y-direction end of the web 32c of the steel beams 32 faces the Y-direction end of the first center plate 51.

[0037] The first segment 611 of the second center plate 61 is joined to the end of the web 32c of the steel beam 323, which extends in the X direction and is joined to the beam-column joint 33 from one side in the X direction. See FIG. 3 for the first segment 611. The first segment 611 of the second center plate 61, which is joined to the steel beam 323, is joined to one surface in the X direction of the first outer plate 52 and to the upper surface of the lower diaphragm 331. The upper flange 32b of the steel beam 323 is joined to one edge of the upper diaphragm 332 in the X direction. The lower flange 32a of the steel beam 323 is joined to one edge of the lower diaphragm 331 in the X direction. The end face of the first segment 611 of the second center plate 61 faces one surface in the X direction of the first outer plate 52.

[0038] The fourth segment 614 of the second center plate 61 is joined to the end of the web 32c of the steel beam 324 that extends in the X direction and is joined to the beam-to-column joint 33 from the other side in the X direction. The fourth segment 614 of the second center plate 61, which is joined to the steel beam 32, is joined to the other surface of the first outer plate 53 in the X direction and the upper surface of the lower diaphragm 331. The upper flange 32b of the steel beam 32 is joined to the edge of the other side in the X direction of the upper diaphragm 332. The lower flange 32a of the steel beam 32 is joined to the edge of the other side in the X direction of the lower diaphragm 331. The end face of the fourth segment 614 of the second center plate 61 faces the other surface of the first outer plate 53 in the X direction. The steel column 31 is joined to the upper end diaphragm 332. In this way, the steel column 31 and the steel beam 32 are joined.

[0039] Next, the operation and effect of the seismic isolation structure according to this embodiment will be described. In the base isolation structure 1 according to this embodiment, a rib plate reinforcement portion 34, in which multiple rib plates 333 are arranged in a grid pattern, is provided at the column-beam joint 33, thereby enabling the structure to accommodate local stresses acting on the base isolation joint. In the base isolation structure 1 according to this embodiment, the lower end diaphragm 331 provided on the spherical sliding bearing 4 not only serves as a diaphragm provided at the bottom of the column-beam joint, but also as a base plate provided on the spherical sliding bearing to support the column-beam joint. Therefore, the base isolation structure 1 according to this embodiment can be reduced in height compared to a conventional base isolation structure 8, which has a base plate 81 as shown in FIG. 14 and a lower end diaphragm 82 provided thereon. Furthermore, in the base isolation structure 1 according to this embodiment, multiple rib plates 333 reinforcing the column-beam joint 33 are provided between the lower end diaphragm 331 and the upper end diaphragm 332, thereby enabling the structure to be reduced in height compared to a conventional base isolation structure 8, which has multiple rib plates 83 provided between the lower end diaphragm 82 and a base plate 81 provided below it as shown in FIG. 14. In this way, the seismic isolation structure 1 according to this embodiment can accommodate local stress acting on the seismic isolation joints without increasing the floor height of the seismic isolation layer 41.

[0040] In the seismic isolation structure 1 according to this embodiment, a rib plate reinforcement portion 34, which is composed of multiple rib plates 333 arranged in a lattice pattern, is provided at the column-beam joint 33. The column skin plate reinforcement portion 342 of the rib plate reinforcement portion 34 is positioned vertically below the skin plate of the steel column 31 and is joined to the steel column 31 via the upper end diaphragm 332. This allows the column skin plate reinforcement portion 342 to transmit the axial force of the steel column 31 and bear the stress of the steel column 31. A cross-shaped reinforcement portion 341 is joined to the inside of the column skin plate reinforcement portion 342, and a peripheral reinforcement portion 343 is joined to the outside of the column skin plate reinforcement portion 342. This allows the axial force of the steel column 31, transmitted to the column skin plate reinforcement portion 342, to be transmitted to the slider 44 of the spherical sliding bearing 4 via the rib plate reinforcement portion 34 and the lower end diaphragm 331. Furthermore, since the web 32c of the steel beam 32 is joined to the outer periphery reinforcement portion 343, the rib plate reinforcement portion 34 can bear the shear force of the column-beam joint portion 33.

[0041] As described above, the rib plate reinforcement 34 has a structure in which three plates, the first center plate 51 and first outer plates 52, 53, each with their plate surfaces facing the X direction and aligned in the X direction, and three plates, the second center plate 61 and second outer plates 62, 63, each with their plate surfaces facing the Y direction and aligned in the Y direction, are assembled in a lattice pattern. Therefore, in the beam-column joint 33 of this embodiment, these plates can distribute stress.

[0042] The cross-shaped reinforcement portion 341 of the rib plate reinforcement portion 34 is welded to the lower end diaphragm 331, the upper end diaphragm 332, and the column skin plate reinforcement portion 342. This gives the cross-shaped reinforcement portion 341 a rigid structure that is resistant to buckling, thereby preventing buckling of the column-beam joint 33.

[0043] The rib plate reinforcement portion 34 is provided beyond the width and depth dimensions of the steel column 31, up to the edge of the lower end diaphragm 331 which serves as the base plate. This allows the bearing stress received by the lower end diaphragm 331 to be transmitted to the steel column 31 even if the slider 44 of the spherical sliding bearing 4 deforms horizontally and moves to the outside of the steel column 31 in plan view.

[0044] Conventionally, rib plates installed on the outer periphery of beam-column joints are joined to the skin plate of the steel column by fillet welding, but there is generally no stiffening plate on the back side of the skin plate, and the design is based on the expectation of the plate bending strength of the column skin plate.In contrast, in this embodiment, a cross-shaped reinforcement part 341 is installed inside the outer periphery reinforcement part 343 via the column skin plate reinforcement part 342, so that the outer periphery reinforcement part 343, cross-shaped reinforcement part 341, and column skin plate reinforcement part 342 are integrated, enabling reliable stress transmission.

[0045] By devising an assembly process for the beam-column joint 33, the lower end diaphragm 331 can be butt-welded to the multiple rib plates 333, making the beam-column joint 33 structure suitable for ultrasonic testing. The quality of the beam-column joint 33 can be controlled by ultrasonic testing.

[0046] The above describes embodiments of the seismic isolation structure and the construction method for the seismic isolation structure according to the present invention, but the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the spirit of the present invention. For example, the number and arrangement of the rib plate reinforcing portion 34 may be set appropriately as long as the plurality of rib plates 333 are arranged in a lattice pattern. In the above embodiment, when the first divided body 621 of the second outer plate 62 and the first divided body 631 of the second outer plate 63 are joined to one side of the first outer plate 52 in the X direction and the fourth divided body 624 of the second outer plate 62 and the fourth divided body 634 of the second outer plate 63 are joined to the other side of the first outer plate 53 in the X direction, the first outer plate 52 and the first outer plate 53 are joined to the lower end diaphragm 331 and the upper end diaphragm 332. The timing for joining the first outer plate 52 and the first outer plate 53 to the lower end diaphragm 331 and the upper end diaphragm 332 may be set as appropriate. [Explanation of symbols]

[0047] 1. Seismic isolation structure 2. Lower structure 3 Superstructure 4. Spherical sliding bearing 6 Second center plate 31 Steel column 32 Steel beam 33 Column beam joint 34 Rib plate reinforcement 41 Seismic isolation layer 51 First Center Plate 52,53 First outer plate 61 Second center plate 62,63 Second outer plate 333 Rib Plate 341 Cross-shaped reinforcement 342 Column skin plate reinforcement 343 Periphery reinforcement 611-614, 621-624, 631-634 Divisions (Second Plate Divisions) 611, 621, 631 First division (Second plate division) 612, 622, 632 Second division body (second plate division body) 613,623,633 Third division (Second plate division) 614,624,634 4th division (2nd plate division)

Claims

1. A substructure; an upper structure provided above the lower structure; a spherical sliding bearing provided between the lower structure and the upper structure, The upper structure has a column-beam joint where a steel column and a steel beam are joined, The spherical sliding bearing is connected below the column-beam joint, The column-beam joint is a lower end diaphragm provided at the lower end and joined to the spherical sliding bearing; an upper end diaphragm provided at the upper end; a rib plate reinforcing portion provided between the lower end diaphragm and the upper end diaphragm, The steel column is joined onto the upper end diaphragm, The steel beam is joined to the lower end diaphragm, the upper end diaphragm, and the side of the rib plate reinforcing portion, the lower end diaphragm, the upper end diaphragm, and the rib plate reinforcing portion are arranged coaxially with the steel column, the rib plate reinforcing portion includes a plurality of rib plates joined to the lower end diaphragm and the upper end diaphragm, A seismic isolation structure in which the plurality of rib plates are arranged in a lattice pattern when viewed in a plan view from the vertical direction.

2. The steel column is a square steel pipe, The rib plate reinforcing portion is a square tube-shaped column skin plate reinforcing portion located vertically below the skin plate of the square steel pipe; A cross-shaped reinforcement portion located inside the column skin plate reinforcement portion in a plan view, and in which the rib plate intersects on the axis of the steel column; The seismic isolation structure according to claim 1 , further comprising: an outer peripheral reinforcement portion positioned outside the column skin plate reinforcement portion in a plan view.

3. The lower end diaphragm is designed to be larger than the steel column in a plan view seen from the vertical direction, The seismic isolation structure according to claim 2 , wherein the rib plates constituting the outer peripheral reinforcing portion are arranged up to the edge of the lower end diaphragm.

4. A construction method for the seismic isolation structure according to claim 1, The plurality of rib plates include: a plurality of first plates whose plate surfaces face a first horizontal direction and are arranged at intervals in the first horizontal direction; a plurality of second plates whose plate surfaces face a second horizontal direction intersecting the first horizontal direction and are arranged at intervals in the second horizontal direction; the plurality of first plates and the plurality of second plates are arranged in a grid pattern, the plurality of second plates are each composed of a plurality of second plate segments whose plate surfaces face the second horizontal direction and are arranged in the first horizontal direction, the second plate segments are disposed between the first plates adjacent to each other in the first horizontal direction and on the outside of the first plates disposed at both ends of the array, a first center plate disposed at a middle portion of the arrangement of the plurality of first plates is joined to the lower end diaphragm; a second center plate segment adjacent to the first center plate in a second center plate arranged in a middle portion of the second plates is joined to the lower end diaphragm and the first center plate; the first center plate and the second plate segment joined to the lower end diaphragm are joined to the upper end diaphragm; a first outer plate arranged on the outside of the arrangement of the plurality of first plates is joined to the lower end diaphragm and the second plate segment already joined to the lower end diaphragm; a second plate segment disposed between the first center plate and the first outer plate of a second outer plate disposed on the outside of the arrangement of the second plates, the second plate segment being joined to the lower end diaphragm, the upper end diaphragm, the first center plate, and the first outer plate; The first outer plate is joined to the lower end diaphragm and the lower end diaphragm; the second plate segment, which is disposed on the outside of the first outer plate in the second outer plate, is joined to the lower end diaphragm and the first outer plate; the second plate segment disposed on the second center plate outside the first outer plate is joined to the steel beam, and joined to the first outer plate; A construction method for a seismic isolation structure in which the steel column is joined to the upper end diaphragm.

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