seismic isolation building

Abstract

To provide a rational and economical method for constructing and building a seismic isolation layer and a seismic isolation layer foundation structure in a seismic isolation structure building. [Solution] In the seismic isolation layer, sliding bearings with rotation mechanisms that can absorb the tilt angle of the support points during an earthquake are used at all load support points that support the weight of the upper structure, and seismic isolation devices for horizontal restoring force (restoring materials) are placed in positions that do not support the weight of the building. The beams that restrain the rotational bending deformation caused by the horizontal deformation of the restoring material are placed in the form of an inverted beam above the seismic isolation layer slab, and their ends are not connected to the foundation structure directly below the sliding support. Only a seismic isolation layer slab is placed on the floor below the seismic isolation layer, and no underground beams are placed to connect the foundation structure directly below the sliding bearings that support the building weight.

Description

[Technical Field]

[0001] The present invention relates to a method for constructing a seismically isolated building. [Background technology]

[0002] Seismic isolation structures are a structural method for increasing the safety of buildings against earthquakes. A seismic isolation building (hereafter referred to as a "seismic isolation building") consists of three parts: a substructure such as a foundation, an upper structure which is the intended building, and a seismic isolation layer installed between the substructure and the upper structure.

[0003] The general understanding is that the seismic isolation layer is composed of isolators (seismic isolation bearings) that deform horizontally while supporting the weight of the upper structure, and dampers that do not support the weight but are intended to absorb vibration energy (earthquake input energy) during an earthquake. There are also seismic isolation bearings that combine both functions. Known types of isolators include various laminated rubber bearings, sliding bearings, and rolling bearings.

[0004] To give a concrete example of a seismic isolation device, first of all, natural rubber laminated rubber bearings are the basic type. High-damping laminated rubber bearings, lead plugs, and Plug-insertion type laminated rubber bearings, such as tin plugs, have been developed. In addition, the rubber material does not support weight and is not laminated, and is intended only for horizontal restoring force. There are also other systems. As for sliding bearings, there are "elastic sliding bearings" (Patent Document 1) that use relatively thin laminated rubber bodies, There is a "rigid sliding bearing" (Patent Document 2) that does not use laminated rubber bodies.

[0005] On the other hand, when looking at the "mounting and installation conditions" of seismic isolation devices, the following points must be considered: Generally, seismic isolation devices control the horizontal resistance force against the horizontal relative displacement between the ground foundation and the superstructure. Any seismic isolation device is based on the premise that horizontal shear deformation occurs between the upper and lower structures, and if the support point on the foundation side below the device tilts, the horizontal performance of the device will be affected.

[0006] In order for a seismic isolation device to exhibit stable horizontal performance, it is generally required that the support point inclination angle of laminated rubber bearings be kept to 1 / 100 (rad) or less, and in the case of elastic sliding bearings with a thin rubber layer in the laminated rubber body, the inclination angle during an earthquake must be limited to 1 / 200 (rad) or less. In sliding bearings, the contact surface between the sliding material and the sliding plate is in full contact condition during sliding movement. It is a necessary and important condition to be able to maintain this. As sliding bearings that can exhibit stable sliding performance without being affected by the inclination angle of the ground-side support point during an earthquake, the "sliding bearing with rotation mechanism" (Patent Document 3) and its advanced version, the "two-stage sliding type sliding bearing with rotation mechanism" (Patent Document 4), have been realized, which have built-in pin supports that can absorb support point inclination angles in all directions, 360°, relative to the vertical axis of the seismic isolation device. In Japan, the construction method of seismically isolated buildings that utilize these various seismic isolation devices began with the placement of various laminated rubber bearings under each column, and the use of laminated rubber bearings that also function as dampers, or the combination of these with separate dampers that do not support the weight of the building.

[0007] After that, as seismic isolation devices such as sliding bearings came into practical use, the following methods of constructing seismic isolated buildings were adopted: The number of cases where the "construction method combining laminated rubber bearings and sliding bearings" (Patent Documents 5 and 6) is adopted has increased.

[0008] Furthermore, as a method for maintaining the resistance of the laminated rubber at that position even if the support point rises up during an earthquake, a method has been proposed in which a seismic isolation device is used in which a sliding bearing is connected in series to the top of the laminated rubber, and the upper flanges of the adjacent laminated rubber are connected together.This method allows the laminated rubber below to generate the same horizontal displacement as the adjacent laminated rubber, even if the sliding bearing above rises up, so that the seismic isolation device at the point where the rise occurs can also exert horizontal resistance (Patent Document 7).

[0009] Furthermore, if a base-isolated building is lifted, rocking vibrations will occur throughout the building, causing tilting deformation of the building. A base-isolated building has been proposed (Patent Document 8) that aims to restrain and suppress the tilting deformation of the building caused by this rocking. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2005-54447 A (elastic sliding bearing) [Patent Document 2] JP 2003-301625 A (rigid sliding bearing) [Patent Document 3] Patent Publication No. 2023-103898 (BSL) [Patent Document 4] Patent Application No. 2024-126058 (BSL-WS) [Patent Document 5] Patent Publication No. 2018-84100 (Laminated rubber + two types of sliding bearings) [Patent Document 6] JP 2022-014608 A (Laminated rubber + elastic sliding bearing) [Patent Document 7] Patent Application No. 2012-129337 (Series connection of laminated rubber and sliding bearing) [Patent Document 8] Patent Application No. Hei 10-311162 (rocking prevention seismic isolation) Summary of the Invention [Problem to be solved by the invention]

[0011] As described above, various proposals have been made regarding the construction of seismically isolated buildings, utilizing the various seismic isolation devices that have been realized to date. However, in any case, for a seismic isolation device to perform normally, regardless of the type of device, it must be able to shear horizontally. Therefore, it is usually necessary to have superstructure beams above the seismic isolation layer where the seismic isolation device is located, and to place underground beams on the seismic isolation layer floor below the seismic isolation layer that connect the foundations that support the seismic isolation devices. Therefore, floor slabs and beams exist above and below the seismic isolation device, and constructing a seismic isolation layer adds one more floor to the structure of a seismically isolated building. The increase in the structural frame by one floor due to the construction of this seismic isolation layer is the main factor in increasing the cost of seismically isolated buildings and is the main obstacle to their widespread adoption.

[0012] To solve this problem, a sliding bearing with a rotation mechanism, BSL (hereafter referred to as BSL seismic isolation device, or simply BSL), has been developed, which has a built-in pin support that can absorb the tilt angle of support points such as pile heads during an earthquake.The "BSL pile head seismic isolation method" has been developed, in which this is placed in the seismic isolation layer.

[0013] However, the seismic isolation device BSL is a sliding bearing and does not have horizontal restoring force, so in order to construct a seismically isolated building, it must be combined with a restoring material such as laminated rubber, and this has been realized as a combined (hybrid) seismic isolation method of ``restoring material (laminated rubber) + BSL.'' In this case, the support points of the BSL, which have a rotation mechanism, can tolerate the tilt angle of the pile head during an earthquake, so underground beams are not required at the locations connecting the support points of the BSL. On the other hand, at the support points where laminated rubber bearings that provide the restoring force are placed, the tilt angle of the pile head during an earthquake must be kept below approximately 1 / 100 (rad), so the placement of underground beams is essential.

[0014] As can be seen in the example of large logistics warehouses that have been attracting attention in recent years, in seismically isolated buildings with very large planar shapes, with one side exceeding 100 meters in length, there are many fulcrums for placing the seismic isolation device BSL, and there are many locations where the underground beams connecting the BSLs can be omitted, so this BSL pile top seismic isolation method can be very effective economically.

[0015] On the other hand, if the size of the seismically isolated building is small, the effect of being able to omit underground beams using this pile-head seismic isolation method is not very pronounced. For example, in the case of a L-shaped building (four columns) with only four columns, priority must be given to placing laminated rubber at the support points, so sliding bearing BSL cannot be placed, and there will be no BSL membrane. Next, if the planar shape is a Japanese-style building (six columns), laminated rubber is used at the four corners, and BSL is placed in only two locations. There is only one underground beam with BSL at both ends, and the reduction effect of the total seven underground beams is only 1 / 7.

[0016] Next, if the planar shape is an eye-shaped building (8 columns), the four corners will be laminated rubber and the rest will be 4 BSLs, so there will be 4 underground beams connecting the BSLs, and the reduction effect of the total 10 underground beams will be 4 / 10 = 2 / 5. Next, if the planar shape is a rice field-shaped building (9 columns), the four corners will be laminated rubber and the rest will be 5 BSLs, so there will be 4 underground beams connecting the BSLs, and the reduction effect of the total 12 underground beams will be 4 / 12 = 1 / 3.

[0017] As described above, in the BSL pile top isolation method, which uses sliding bearings BSL with a rotation mechanism, great economic benefits can be expected from omitting the pile top underground beams on the seismic isolation layer floor surface in the case of buildings with large planar shapes, but in ordinary buildings such as the many small apartment buildings in society, the economic benefits of omitting the underground beams are not very pronounced, and the reality is that the pile top isolation method has not yet become a breakthrough in the spread of seismic isolation structures in ordinary small to medium-sized seismic isolated buildings. [Means for solving the problem]

[0018] The present invention has been made to solve the above problems, and the following configurations are means for solving the above problems and achieving the object. <Configuration 1> (BSL + seismic isolation layer slab at all supports, no underground beams) Multiple seismic isolation devices between the lower structure and upper structure The seismic isolation layer in which A seismically isolated building that has the following characteristics: (a) The upper structure, at least on the lowest floor, is composed of a framework having columns and girders, and directly below the columns are vertical load support points that support the weight of the upper structure, and there are no other vertical load support points that support the weight of the upper structure other than directly below the columns. (b) The seismic isolation device is equipped with two types of devices: a sliding support that can support the vertical load of the upper structure and move horizontally, and a horizontal restoring force device that exerts a horizontal restoring force that returns the upper structure to its original position in response to relative horizontal displacement of the upper structure with respect to the lower structure. (c) The sliding support is composed of two parts: a sliding plate and a slider. The sliding plate is a flat plate and is fixed to the upper structure. (d) The slider disposed below the sliding plate has a sliding material disposed on its upper surface or has an upper surface that is treated to have a sliding surface. The slider body located below it is designed to absorb the tilt angle of the lower structure during an earthquake, and is separated into two or three parts above and below, with each contact surface being a combination of a concave spherical surface and a convex spherical surface with different radii of curvature. (e) The sliding bearings are arranged at all of the vertical load support points on which the weight of the upper structure acts. (f) The horizontal restoring force device is arranged at a position other than the vertical load support point and at a position relative to the center of gravity of the upper structure such that the sum of the rotational moments around the vertical axis of the center of gravity due to the horizontal restoring forces is approximately zero. (g) The lower structure includes: The base isolation layer has a base isolation layer slab on the entire lower surface of the base isolation layer, and a foundation frame that supports the sliding bearing directly below the sliding bearing. There are no underground beams connecting the foundation structures.

[0019] <Configuration 2> (BSL for sliding bearing + rubber bearing for restoring material) In the base-isolated building according to configuration 1, A seismically isolated building, characterized in that the sliding bearing and the horizontal restoring force device are as follows. (a) The sliding bearing is a sliding bearing with a rotation mechanism for absorbing the tilt angle of the lower structure during an earthquake, and the slider that constitutes the sliding bearing is composed of two members, from top to bottom, a convex member with a convex spherical surface on the contact surface and a concave member with a concave spherical surface on the contact surface, or is composed of three members, a concave member, a convex member and a concave member, and the radius of curvature r of the convex spherical surface and the radius of curvature R of the concave spherical surface satisfy the relationship r<<R. (b) The horizontal restoring force device is a rubber bearing including either a laminated rubber bearing or a non-laminated rubber body, or both. (c) The laminated rubber bearing is any one of or a combination of a natural rubber laminated rubber bearing, a high-damping rubber laminated rubber bearing, and a plug-insertion type laminated rubber bearing containing lead, tin, or other plugs. (d) The upper surface of the rubber bearing is fixed to an upper mounting body that is integrated with the main beam, sub-beam or slab of the upper structure, and the lower surface of the rubber bearing is fixed to a lower mounting body, which is integrated with an inverted beam-type mounting beam configured in an inverted beam shape above the seismic isolation layer slab or the seismic isolation layer slab. (e) The inverted beam-type attachment beam is integrated with the seismic isolation layer slab but is not connected to the foundation body.

[0020] <Configuration 3> (Different foundation structure methods and their mixture) In the base-isolated building according to the configuration 1 or 2, A seismically isolated building characterized in that the foundation foundation work, pile foundation work, etc. (hereinafter referred to as the "foundation structure method") that supports the foundation structure directly below the sliding support, which is integrated with the seismic isolation layer slab, is one of the following. (a) A foundation structure method using a direct foundation in which the foundation body is in direct contact with the supporting ground. (b) A short pile support foundation structure in which the foundation body is supported by one or more short piles. (c) A long pile supported foundation structure in which the foundation body is supported by one or more long piles. (d) A foundation structure method that employs any of the following pile types for the piles described in (b) and (c) above: cast-in-place concrete piles, various precast concrete piles, various steel pipe piles, steel pipe concrete piles, or connected steel pipe piles and precast concrete piles. (e) A foundation structure method in which different types of piles as described in (d) above are used in different foundation structures. (f) A mixed foundation structure method that combines the different foundation structure methods described in (a) to (e) above.

[0021] <Configuration 4> (without seismic isolation slab) In the seismically isolated building according to configuration 3, , A seismically isolated building characterized in that a portion of the seismic isolation layer slab in the substructure has been removed, or the seismic isolation layer slab has been completely removed. <Configuration 5> In the base-isolated building according to the configuration 1 or 2, A seismically isolated building characterized in that a portion of the seismic isolation layer slab in the substructure has been removed, or the seismic isolation layer slab has been completely removed. [Effects of the Invention]

[0022] (Effects of Configurations 1 and 2) First, the effect of configuration 1 in which all supports are sliding bearings with rotation mechanisms will be described. (Effect 1: No need for underground beams even in small buildings → Cost reduction and shortened construction period) The present invention is a hybrid seismic isolation method that combines a sliding bearing with a rotation mechanism, represented by the seismic isolation device BSL, with laminated rubber. As described in paragraphs 0014 to 0016, the economic effect of being able to omit underground beams in the seismic isolation layer pit due to the effect of the sliding bearing with a rotation mechanism (seismic isolation device BSL) was previously hardly realized in small-scale seismic isolated buildings, but with the present invention, it is possible to omit all underground beams connecting the fulcrums of all seismic isolation devices, regardless of the size of the seismic isolated building. In other words, the effect of the present invention can be succinctly expressed as "eliminating the need for underground beams on the seismic isolation layer floor surface, regardless of the size of the seismic isolation building."

[0023] In the seismic isolation layer pit, if sliding bearings with rotation mechanisms are placed on both ends of the underground beam, then the underground beam is not necessary, but if there are restoring laminated rubber at both ends or one end, then an underground beam must be placed to suppress the pile head inclination angle during an earthquake at the support point where the laminated rubber is placed. Even a small-scale seismically isolated building requires a minimum of four restoring laminated rubber bearings, so they are placed at the support points at at least the four corners of the building. This has been the conventional wisdom, and as long as attention is focused on the cost of seismic isolation devices, placing restoring laminated rubber bearings at the four corners of the building and sliding bearings with rotation mechanisms at the remaining support points has been considered economically rational from the perspective of seismic isolation device costs, and this placement policy and plan is fully adopted in the design of actual seismically isolated buildings.

[0024] However, in this invention, rather than just considering the cost of the seismic isolation device, we take a comprehensive view that includes the seismic isolation device, the seismic isolation layer pit, and the entire foundation structure.By placing sliding bearings with rotation mechanisms at all support points, although the cost of the device alone increases, by "eliminating the need for underground beams for the entire building," we have realized that we can produce far greater benefits in many ways, not just in terms of economy.

[0025] Generally, the pillars at the four corners of a building only have a commanding area of ​​about 1 / 4 of the central pillars of the building, so their long-term support weight is relatively small. However, since the restoring laminated rubber must ensure horizontal deformation performance in the event of a large earthquake, it is not possible to use small laminated rubber even if the support load is small. In contrast, with sliding bearing BSLs with rotation mechanisms, the device size can be selected according to the magnitude of the support load. Smaller size devices can be selected for BSLs at the four corners of a building, where the long-term support load is small, so the additional cost of BSLs at the four corners is relatively small. On the other hand, the cost reduction effect of not needing underground beams for the entire building is very large, and because there are no underground beams, the base of the foundation of the seismic isolation pit is flat, so the amount of soil excavated for the foundation is reduced and excavation efficiency is extremely high, which has a significant effect in shortening the construction period.

[0026] (Effect 2: Rationalization of restoration equipment possible → cost reduction and shortened construction period) By using sliding bearings with rotation mechanisms at all supports, the position of the laminated rubber as a restoring material is removed from the support points for the building weight, which produces another major effect. In other words, the horizontal deformation performance of laminated rubber is mainly governed by two factors: 1) the amount of horizontal shear deformation of the rubber layers, and 2) the buckling phenomenon that accompanies horizontal deformation, but eliminating the need for load support performance in the restoring device laminated rubber means that the laminated rubber is freed from the constraints of the buckling phenomenon mentioned above.As a result, the deformation performance of the laminated rubber is improved, and at the same time, the degree of freedom in its shape and specification conditions is greatly increased, allowing for economically advantageous selection. In other words, since there is no risk of buckling in laminated rubber, if the building weight is small, it becomes possible to select laminated rubber with a small diameter or laminated rubber with a large thickness per layer and a small number of layers, and in the extreme case, it becomes possible to select a single rubber as a restoring material, which has a great economic effect.

[0027] (Effect 3: Streamlined fixing method for restoration devices, reverse beam method → ​​cost reduction, shortened construction period) The position of the restoring device that does not support the load will be any position other than the support point of the building. Because there is only a slab below the seismic isolation pit, the lower mounting body of the restoring material (laminated restoring rubber) is placed on the slab of the seismic isolation pit, and its bending deformation is restrained by placing an inverted beam-type mounting beam on the top surface of the slab. Reinforcement can be placed above the pit slab surface, and formwork work involves installing beam-type side formwork on the slab surface, and concrete pouring is also done on the slab, making work extremely easy and efficient. Furthermore, since the ends of the inverted beams are not connected to the foundation frame at the device support points (connections are not permitted in order to avoid bending and restraining the foundation frame at support points such as pile heads), there is no need to bend and fix the beam reinforcement ends, and the reinforcement shape is extremely simple, making reinforcement work easy.

[0028] (Effect 4: Increased freedom of placement of restoring materials, improved eccentricity and torsion control) This also significantly increases the degree of freedom in the placement of the restoring materials on the building floor plan. Two important points are that the resistance force of the restoring materials is not eccentric to the center of gravity of the building (i.e., the eccentricity rate is as close to zero as possible), and at the same time, the torsional resistance of the restoring materials is as large as possible. The placement position of the restoration material is not restricted by the position of the building's columns, so any position can be freely selected. Therefore, a position where the resistance force of the restoration material is symmetrical with respect to the center of gravity of the building and as far away from the center of gravity as possible is advantageous.

[0029] (Effect of Configuration 3) (Effect 5: It is now possible to adopt and mix different types of foundations) In the design of building foundation structures, the traditional earthquake-resistant design principle was that the use of different types of foundations in the same building should be avoided. In other words, a design in which, depending on the position of the columns, spread foundations, short pile foundations, and long pile foundations are mixed within the same building is not recognized as a conventional structural design judgment. This is because it is not easy to determine the seismic force that will be borne at each foundation position, and there are many unknowns in the seismic design, which may be dangerous from an engineering perspective.

[0030] However, in the present invention, which employs sliding bearings with rotation mechanisms at all column support points and does not restrict the rotation performance of the foundation structure during an earthquake, even if different rotation angles (tilt angles) occur at each column support point during an earthquake, the sliding bearings with rotation mechanisms at each support point can absorb the respective tilt angles during an earthquake, preventing any impact on the sliding performance at each position, so the occurrence of different tilt angles during an earthquake at each support point does not pose an obstacle to earthquake-resistant design.

[0031] In actual building design, the ground conditions at construction sites vary widely, and depending on the column position, there may be a mixture of cases where the supporting layer is shallow and a spread foundation is appropriate, or conversely, where the supporting ground is deep and long piles are required. In such cases, it has been required to avoid mixing different types of foundations, so it has been very difficult to design a unified foundation method for all column positions, and in some locations it has been necessary to mix foundation methods that are not suitable for the ground conditions.

[0032] In contrast, with the present invention, there is no need to uniformly control the inclination angle of the support points at each column position during an earthquake, so it is possible to freely select and adopt a foundation structure method that suits the ground conditions at each column position, allowing for extremely rational design of the foundation structure to suit the ground conditions. Compared to the conventional design method that prohibited the mixing of different types of foundations in the design of foundation structures, the design that allows the free mixing of different types of foundations is a breakthrough in the design of foundation structures.

[0033] (Effect of Configuration 4) (Effect 6: No longer requires a rigid foundation → Allows for input of different earthquake motions) In the earthquake-resistant design of buildings up to now, the principle has been that the earthquake motion input to the building should be the same at all column positions and foundation input positions. There is no guarantee that the earthquake motion input to an actual building will satisfy this condition, but in previous earthquake-resistant designs, the earthquake-resistant design technology for actual buildings could only handle the simplified condition of the same earthquake motion being input at the foundation position of each column support point. For this reason, at the foundation level of the building, a strong RC foundation slab is poured across the entire building, and the seismic design is carried out on the assumption that a rigid floor condition (the horizontal displacement of each column position moves in the same way) exists for the entire building. In the design of the building, the seismic design system is constructed on the assumption that a rigid floor condition exists for each floor of the superstructure as well, and in the design of the foundation structure, the seismic design system for the foundation structure is constructed on the assumption that this rigid floor condition exists at the foundation level and at the input point of earthquake motion.

[0034] However, in recent years, examples have emerged of designs for extremely large buildings with side lengths well exceeding 100 meters, which raise serious doubts about the validity of the assumptions that a rigid floor condition exists at the foundation level and that the same seismic motion is input at each column position. For example, because the side length is very large, the depth of the supporting layer of the ground may vary greatly depending on the location, and when inputting seismic motion, there is a practical issue of time lag in the input seismic motion over a long plane depending on the direction from which the seismic motion is transmitted, the so-called phase difference input problem.

[0035] To address these complex issues in earthquake-resistant design, in recent years it has become possible to construct a 3D FEM analysis model of the ground over a fairly wide area centered on the building location, and perform a 3D nonlinear propagation analysis of earthquake motion to determine the input earthquake motion depending on the planar position within the building. In addition, when analyzing the earthquake response of buildings, it is also possible to perform ``simultaneous multi-point input'' time history earthquake response analysis, which inputs seismic motion that varies depending on the planar position of the foundation. These special seismic design methods are currently extremely cutting-edge technologies, and the reality is that they have not yet been adopted as general design methods. However, the applicant has gained new insight into this issue through his experience in design and analysis.

[0036] To summarize briefly, in simultaneous multi-point input analysis of a building, when different earthquake motions are input depending on the location, the impact on the building due to the differences in earthquake motion at each location cancels out the input effect of the earthquake motion, and it has been found that in most cases the most severe conditions for earthquake motion input to a building are when the same earthquake motion with the same phase is input to the entire building. Furthermore, many analytical results have been obtained showing that even in cases of phase difference input problems involving time lags in long buildings, severe torsional vibrations are not induced.

[0037] Taking these analysis results into consideration, the conventional rigid floor assumption, which states that "the movement of each column position in the horizontal plane is controlled uniformly" at the building foundation, is a conservative assumption when evaluating the seismic performance of a building, but it can be determined that "it is not necessarily an absolute requirement in seismic design." In other words, Configuration 4 of the present invention incorporates this cutting-edge knowledge that "rigid floor conditions at the foundation input position can be made unnecessary in earthquake-resistant design," thereby increasing the degree of freedom in foundation design and opening the way to rational, economical design. However, this knowledge is currently considered to be special knowledge that is held by only a very small number of engineers, including the applicant, and therefore we believe that we should avoid carelessly expanding its application to people who do not fully understand the issue. [Brief explanation of the drawings]

[0038] [Figure 1] This is a conventional seismically isolated building that uses both a restoring device and a sliding bearing. (1) is a floor plan (top view) of the lowest floor (first floor) of the superstructure, and (2) is a plan (top view) of the seismic isolation device layout in the seismic isolation layer. [Figure 2] This is a seismically isolated building of the present invention that uses both a restoring device and a sliding bearing. (1) is a floor plan (top view) of the lowest floor (first floor) of the superstructure, and (2) is a plan (top view) of the seismic isolation device layout in the seismic isolation layer. [Figure 3] (1) is a cross-sectional view of a conventional seismically isolated building. (2) is a cross-sectional view of the seismically isolated building of the present invention, showing the column alignment. (3) is a cross-sectional view of the seismically isolated building of the present invention, showing the alignment of the restoration material. [Figure 4] An explanatory diagram of the slider configuration of a sliding support bearing with a rotation mechanism. (A) is for a three-component configuration, where (1) is a plan view of the upper concave member, (2) is a cross-sectional view, and (3) is a plan view of the lower concave member. (B) is for a two-component configuration, where (1) is a plan view of the upper convex member, (2) is a cross-sectional view, and (3) is a plan view of the lower concave member. (B') is the same as (B) for a two-component configuration, but rotated 45°. (1) is a plan view of the upper convex member, (2) is a cross-sectional view in the diagonal direction, and (3) is a plan view of the lower concave member. [Figure 5] Results of a demonstration test using a full-scale device that confirmed that the tilt angle of the support point (pile head) does not affect the sliding performance of sliding bearings with a rotation mechanism [Figure 6] The layout of seismic isolation devices and the foundation structure plan for a large-scale seismic isolation building (1) is the layout plan of the seismic isolation devices (top view) (2) is the cross-sectional configuration diagram of the seismic isolation layer and foundation DETAILED DESCRIPTION OF THE INVENTION

[0039] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (Figure 1: Conventional seismic isolation device layout plan) Figure 1 shows the arrangement of devices in a conventional seismically isolated building and the construction method of the structures above and below it, for comparison with Figure 2, which explains the features of the present invention. Figure 1(1) is a top-down view showing the floor plan of the lowest floor (first floor) of the upper structure, and Figure 1(2) is a top-down view showing the arrangement of seismic isolation devices in the seismic isolation layer. When a seismic isolation device is "composed of a combination of sliding bearings and horizontal restoring force devices (abbreviated as restoring materials)," as shown in Figure 1 (2), in a relatively small seismically isolated building, the restoring materials are placed at the four corners of the building, and sliding bearings are placed at the other column positions.

[0040] In this case, as shown in Figure 1 (1), large girders are placed on the floor of the superstructure to connect all of the columns. On the seismic isolation layer pit floor in Figure 1 (2), in order to suppress the tilt angle during an earthquake at the support points (pile heads) of the restoring materials (laminated rubber bearings are a typical example) placed at the four corners, underground beams must be placed at the locations shown by dashed lines, and if "sliding bearings with rotation mechanisms" are used for the sliding bearings, the underground beams can be omitted if both ends are sliding bearings with rotation mechanisms. However, when looking at the entire base isolation layer, as long as there is restoring material, it is not possible to omit all of the underground beams. In this example, of the total 12 underground beams, only the four cross-shaped ones in the center can be omitted.

[0041] (Figure 2: Layout of the seismic isolation device of the present invention and plans for the upper structure and lower structure) FIG. 2 shows the layout method of the seismic isolation device of the present invention and the structural plan of the upper structure and lower structure in the same building plan as FIG. A feature of the present invention is that "sliding bearings with rotation mechanisms" are placed at all nine of the column positions (support points) that support the weight of the superstructure. That is, in Figure 2 (2), sliding bearings with rotation mechanisms 21 are placed under all of the column positions. As a result, no underground beams are placed on the floor slab of the seismic isolation layer pit, and only floor slab 41 exists on the seismic isolation layer pit floor.

[0042] On the other hand, the horizontal restoring force device (restoring member) 30 is placed at a position other than the support point of the column, and this restoring member (laminated rubber) does not bear vertical load. Therefore, if this restoring member is a laminated rubber bearing or a rubber bearing consisting only of rubber, buckling due to horizontal deformation does not occur, and horizontal shear deformation due to elongation deformation of the rubber material is exerted.

[0043] (Figure 3: Cross-sectional structure of the seismic isolation layer, (1) Conventional seismic isolation, (2) (3) This invention) The method of mounting the seismic isolation devices 20, 30 is shown in the plan view of FIG. 2(2) and the cross-sectional view of FIG. 3(3). That is, the upper surface of the restoring material 30 is fixed to an upper mounting body 31 that is integrated with the upper structure 1, and the lower surface of the device 30 is fixed to a lower mounting body 32 that is integrated with the floor slab 41 of the seismic isolation layer pit. The upper mounting body 31 is integrated with the floor slab 11 and the superstructure 1 by the joists 14 of the superstructure. The lower mounting body 32 has its bending deformation (rotation) restrained by an inverted beam-type mounting beam 43 configured in an inverted beam shape above the seismic isolation layer slab 41, and this inverted beam-type mounting beam 43 is not connected to the sliding-bearing foundation body 44 or piles 45 located at the load-bearing points. Therefore, the inverted beam-type mounting beam 43, which restrains the bending deformation of the restoring member 30 during an earthquake, is not subjected to rotational deformation of the pile head during an earthquake, and no seismic stress is generated from the pile head. This inverted beam-type mounting beam 43 is positioned to restrain the rotational deformation of the restoring member 30 during an earthquake, and bears bending stress at the end connected to the restoring member 30, but the opposite end of this beam 43 stops at the slab position, so the bending stress at that end during an earthquake is zero and it only transmits shear force to the slab 41.

[0044] With the above-described configuration, the structure of the seismic isolation layer of the present invention requires only the floor slab 41, and a configuration is realized in which there are no underground beams at all in the seismic isolation layer. In other words, in the cross-sectional view of conventional seismic isolation, Figure 3(1), there is an underground beam 42 below the seismic isolation layer slab 41, and it is integrated with the foundation body 44 of the lower structure below the seismic isolation device and the piles 45, so during an earthquake, large seismic stresses are generated due to rotational deformation of the pile heads.In contrast, in the present invention, as shown in the cross-sectional views of Figures 3(2) and (3), there is no underground beam in the seismic isolation layer pit, and the structure is such that pile head stresses are not generated due to the pile head tilting during an earthquake.

[0045] As shown in the cross-sectional views of the present invention, Figures 3(2) and (3), the underside of the seismic isolation layer floor slab 41 has no beams and is a simple flat plate shape, so excavation work for the foundation is simple and easy, and along with reducing the amount of excavated soil, there is no need for retaining walls or underground formwork work to form underground beams, which greatly increases the efficiency of excavation work and makes earthwork and foundation work extremely economical.

[0046] As shown in Figure 3 (3), the inverted beam type mounting beam 43 that restrains the rotational deformation of the restoring material 30 in this invention is located above the seismic isolation layer pit floor slab 41, so that the reinforcing bar arrangement work for the cross section of this beam and the formwork work for the side of the beam can be carried out on this floor slab 41, and the concrete pouring work is also extremely easy.

[0047] (Figure 4: How to configure the slider rotation mechanism to create a "sliding bearing with rotation mechanism") If the support points, such as the pile heads that support the sliding bearing, tilt during an earthquake, the sliding performance of the sliding bearing, which is based on full-surface contact conditions, can be significantly affected.To avoid the effects of the tilt angle of the sliding support point during an earthquake, a sliding material located on the top surface of the sliding bearing slider or a rotation mechanism that can absorb the support point tilt angle between the sliding surface and the lower support point is required. Figure 4 shows how to introduce a rotation absorption mechanism into the slider of a sliding bearing. In either case, the slider must be divided into two or three components. Figure 4(A) shows a three-component configuration, Figure 4(B) shows a two-component configuration, and (B') is (B) rotated 45 degrees.

[0048] The left side of Figure 4 (A) shows a slider configuration consisting of three components, with an intermediate double-sided convex component placed between an upper concave component and a lower concave component. In both cases, the contact surfaces of the concave component are concave spherical and the convex spherical, with the radius of curvature r of the convex spherical surface and the radius of curvature R of the concave component satisfying the relationship r<<R. The two right columns (B) and (B') in Figure 4 show cases where the slider is made up of two components: a convex component on the top and a concave component on the bottom, and the radii of curvature of the contact spherical surfaces of the two components are similarly in the relationship r<<R.

[0049] The positional deviation limiting bolt (guide pin) 244, which is fixed to the lower concave member shown at the planar corner of Figure 4(B)(B') and inserted into a loose hole 246 with ample space in the upper convex member, is a safety guide measure that prevents excessive lateral deviation in the planar positions of the upper and lower members while allowing for relative inclination.

[0050] 4(B')(2) shows a positioning hanging eyebolt 245 that fits almost perfectly into the inner diameter of the upper loose hole 246 of the guide pin 244 provided at the corner of the upper convex member. This eyebolt 245 makes it easy to hang and handle the device during assembly work in the factory, and also makes it possible to accurately position the relative horizontal positions of the lower concave member and the upper convex member when installing the device on site. Furthermore, this eyebolt will be removed once the slider installation work on site is completed.

[0051] (Figure 5: Effect of "sliding bearing with rotation mechanism": Demonstration data showing that the inclination angle of the support point does not affect sliding performance) Figure 5 shows the results of measuring the change in the coefficient of sliding friction when a sliding performance test was conducted using an actual sliding bearing BSL with a rotation mechanism, with the maximum tilt angle at the support point set to 0 (no tilt), 1 / 50, 1 / 33, and 1 / 20 (rad) and variable tilt (the tilt angle also fluctuates in response to the horizontal sliding displacement). As shown in this figure, the test results showed that when the maximum inclination angle at the support point was ±1 / 50 (rad), the sliding friction coefficient ratio was 1.006 (a variation of 0.6%) compared to no inclination, when the maximum inclination angle at the support point was ±1 / 33 (rad), the sliding friction coefficient ratio was 0.997 (a variation of -0.3%), and when the maximum inclination angle at the rotating support point was ±1 / 20 (rad), the sliding friction coefficient ratio was 0.995 (a variation of -0.5%).It has been confirmed that with the BSL sliding bearing with a rotating mechanism, the sliding performance does not vary by even 1% even when an inclination angle of 1 / 20 (rad) occurs at the support point during an earthquake. Furthermore, the maximum inclination angle of the pile head during an earthquake is approximately 1 / 50 to 1 / 40 (rad), and BSL has an allowable inclination angle that is twice that.

[0052] In this invention, sliding bearings with rotation mechanisms are used at all column support points, and the rotation performance of the foundation frame at those support points during an earthquake is not restricted. Therefore, if the ground conditions vary, such as the depth of the bearing layer of the ground varying depending on the support point, it is expected that the tilt angle of the support point (pile head) during an earthquake will vary depending on the support point location. However, even if the tilt angle of such support points during an earthquake varies depending on the position, the sliding bearings with rotation mechanisms can avoid the influence of the support point tilt angle, so stable sliding performance can always be demonstrated. To put it another way, if sliding bearings with rotation mechanisms are used at all support points, there is no need to worry about differences in the tilt angle of each support point during a major earthquake.

[0053] (Figure 6: Design example of a seismically isolated building that combines various types of foundations) In actual building design, the ground conditions at construction sites vary widely, and depending on the location, there may be a mixture of locations where the bearing layer is shallow and a spread foundation is appropriate, and conversely, locations where the bearing layer is deep and long piles are required. In particular, when the floor plan of a building is long, the ground conditions may vary greatly depending on the position of the columns even within a single building. Under these conditions, the present invention does not require uniform control of the support point inclination angle during an earthquake that occurs at each column position, making it possible to freely adopt different foundation structure methods that suit the ground conditions at each column position, and to select and design an appropriate foundation structure to suit the ground conditions.

[0054] Figure 6 shows an example of a design for a large-scale seismically isolated building that uses a mixture of different foundation types to suit different ground conditions at different locations. Figure 6(1) is a plan view (top-down view) of the seismic isolation layer pit, showing the layout of the seismic isolation devices, a plan view of the seismic isolation layer pit floor, and the shape of the top surface of the foundation body using dashed lines. Figure 6(2) shows the cross-sectional configuration from the seismic isolation layer pit to the supporting layer of the ground below.

[0055] First, as a seismic isolation device, sliding bearings 21 with rotation mechanisms are placed at all column support points, and laminated rubber bearings 30 are placed as restoring materials at positions that do not support the weight of the building. The restoring members 30 are arranged in sets of four in a square shape near both ends of the building. This is to efficiently arrange small beams on the upper structure side and fixed beams in the reverse beam format in the seismic isolation pit on the lower structure side. This square arrangement makes it possible to restrain the bending (rotational) deformation of the restoring members with a minimum number of beams in both the X and Y directions.

[0056] Next, looking at the type of foundation structure that supports the seismic isolation devices (sliding bearings) 21 at the load-bearing points of the columns that support the weight of the building, a direct foundation type 51 is adopted for the two columns at both ends of the building, as the supporting ground is shallow. Next, in the third and fourth columns from the left of the building, the supporting ground is a little too deep for direct foundations, so cast-in-place concrete piles 52 are used, and near the center of the building where the supporting layer is even deeper, pile foundations 53 using prefabricated piles are used. As described above, a major feature of the present invention is that it allows for the free mixing and adoption of foundation types that are considered to be the most appropriate and rational in response to the ground conditions at the support points. This is because by using sliding bearings with rotation mechanisms at all support points, the effects of the degree of occurrence and differences in the tilt angle of the support points (pile heads) during an earthquake are completely eliminated.

[0057] Another major feature of the present invention is that there are no underground beams connecting each foundation structure, i.e., the direct foundation footings and the foundation structures at the pile heads, and the only structural member that constitutes the seismic isolation layer pit floor is the floor slab 41. Furthermore, the beams for the restoration materials 30, which are arranged in groups of four, are fitted with inverted restraint beams 43, but are not connected to the foundation structure at the support points of the columns, the direct foundation footing, or the foundation structure above the pile foundation.

[0058] Next, let us look at the floor slab 41 of the seismic isolation pit shown in Figure 6(1). In this design example, the floor slab 41 is placed across almost the entire plane of the floor surface of the seismic isolation layer pit, but there is a section 40 near the center of the plane where the floor slab 41 does not exist. In conventional foundation structural design, the basic condition is that the assumption of a rigid floor (each support point undergoes the same horizontal displacement during an earthquake) is valid across the entire floor plan of the building. However, in the case of a large building, it is thought that the condition that all support points undergo the same horizontal displacement during an earthquake is difficult to achieve in reality, and when the depth of the supporting layer varies greatly depending on the position, as in the ground shown in Figure 6 (2) here, the input earthquake motion is thought to be different depending on the position.

[0059] In a recent analytical study conducted by the inventor, a nonlinear propagation analysis of earthquake motion was carried out using a 3D FEM model of the ground in a complex ground where the ground structure is not layered but the depth of the bearing layer varies greatly depending on the position. The results confirmed that even when earthquake motion of the same phase is applied to the basement position, the earthquake motion acceleration waveform on the ground surface varies greatly depending on the position. Furthermore, when conducting an earthquake response analysis of simultaneous multi-point input, in which different earthquake motions are input depending on the position at many support points of seismic isolation devices, it has been confirmed that the maximum earthquake response of the upper building is actually easier (lower) than when earthquake motion input of the same phase is given to all support points. This can be understood to mean that the input earthquake motions that differ depending on the position cancel each other out, resulting in favorable (safe) input conditions for the upper structure.

[0060] Based on these results, it is not necessary to deliberately align the input earthquake motion to the same phase at all input positions of all supports of a long building in a horizontal plane, and simultaneous input of different earthquake motions is acceptable. This invention is based on the results of the latest analytical studies on the simultaneous multi-point input of different earthquake motions as described above and the latest knowledge based on them regarding their effects on building response, and adopts and introduces into building design an advanced engineering judgment (which deviates from conventional common sense in earthquake-resistant design) that "for buildings that are long in plan, the assumption of a rigid floor as an earthquake input condition is unnecessary." According to the present invention, in a long, planar, seismically isolated building, by introducing sliding bearings with rotation mechanisms to all supports, it is possible to eliminate all of the underground beams in the seismic isolation layer that connect all supports in a long, large seismic isolation layer pit, and it is also possible to partially or completely eliminate the floor slab itself in a long, large seismic isolation layer pit. [Explanation of symbols]

[0061] 1: Upper structure of seismically isolated building (general term) 11: Floor slab of superstructure 12: Superstructure pillar 13: Superstructure girder 14: Superstructure beam 2: Seismic isolation device (general term) 20: Sliding bearing 21: Sliding bearing with rotation mechanism 22: Slide plate of sliding bearing 23: Foundation frame to fix the sliding plate 24: Slider of sliding bearing 241: Sliding material (or sliding surface) 242: Convex part of slider 243: Slider recess material 244: Bolt (guide pin) for limiting positional deviation of uneven parts 245: Hanging eyebolt for positioning uneven parts 246: Loose Hole 3: Horizontal restoring force device (restoring material) 30: Laminated rubber bearing (or rubber body) as a restoring material 31: Upper mounting body for restoration material 32: Lower mounting body for restoration material 4: Lower structure (general term) 40: Omitted seismic isolation pit floor slab (area without floor slab) 41: Floor slab of the lower structure (seismic isolation pit floor slab) 42: Substructure girder (earthquake-resistant pit girder, underground pile cap beam) 43: Inverted beam type mounting beam for fixing restoration material 44: Substructure foundation 45:Pile 46: Retaining wall around the seismic isolation layer pit of the lower structure 5: Basics 51:Direct foundation 52: Cast-in-place concrete foundation 53: Pile foundation (prefabricated pile) 6: Ground 61: Surface ground 62:Support layer

Claims

1. A seismically isolated building having a seismic isolation layer with multiple seismic isolation devices arranged between the lower structure and the upper structure, and having the following characteristics: (a) At least the lowest floor of the superstructure is composed of a framework having columns and girders, and directly below the columns are vertical load support points that support the weight of the superstructure, and there are no other vertical load support points that support the weight of the superstructure other than directly below the columns. (b) The seismic isolation device is equipped with two types of devices: a sliding support that can support the vertical load of the upper structure and move horizontally, and a horizontal restoring force device that exerts a horizontal restoring force that returns the upper structure to its original position in response to relative horizontal displacement of the upper structure with respect to the lower structure. (c) The sliding support is composed of two parts: a sliding plate and a slider, and the sliding plate is a flat plate and is fixed to the upper structure. (d) The slider disposed below the sliding plate has a sliding material disposed on the upper surface thereof or the upper surface thereof is treated to have a sliding surface. The slider body located below it is designed to absorb the tilt angle of the lower structure during an earthquake, and is separated into two or three members above and below, with each contact surface being a combination of a concave spherical surface and a convex spherical surface with different radii of curvature. (e) The sliding bearings are arranged at all vertical load support points where the weight of the upper structure acts. (f) The horizontal restoring force device is disposed at a position other than the vertical load support point and at a position where the sum of the rotational moments around the vertical axis of the center of gravity due to the horizontal restoring forces is approximately zero relative to the center of gravity of the upper structure. (g) The substructure has a seismic isolation layer slab on the entire lower surface of the seismic isolation layer, and a foundation body directly below the sliding bearing that supports the sliding bearing, but does not have underground beams connecting the foundation body.

2. The base-isolated building according to claim 1, A seismically isolated building, characterized in that the sliding bearing and the horizontal restoring force device are as follows. (a) The sliding bearing is a sliding bearing with a rotation mechanism for absorbing the tilt angle of the lower structure during an earthquake, and the slider that constitutes the sliding bearing is composed of two members, from top to bottom, a convex member with a convex spherical surface on the contact surface and a concave member with a concave spherical surface on the contact surface, or is composed of three members, a concave member, a convex member and a concave member, and the radius of curvature r of the convex spherical surface and the radius of curvature R of the concave spherical surface satisfy the relationship r<<R. (b) The horizontal restoring force device is a rubber bearing including either a laminated rubber bearing or a non-laminated rubber body, or both. (c) The laminated rubber bearing is any one of a natural rubber laminated rubber bearing, a high-damping rubber laminated rubber bearing, and a plug-insertion type laminated rubber bearing containing a lead plug or a tin plug, or a combination thereof. (d) The upper surface of the rubber bearing is fixed to an upper mounting body that is integrated with the main beam, sub-beam or slab of the upper structure, and the lower surface of the rubber bearing is fixed to a lower mounting body, which is integrated with an inverted beam-type mounting beam configured in an inverted beam shape above the seismic isolation layer slab or the seismic isolation layer slab. (e) The inverted beam type attachment beam is integrated with the seismic isolation layer slab but is not connected to the foundation body.

3. The base-isolated building according to claim 1 or 2, A seismically isolated building characterized in that the foundation foundation work and pile foundation work (hereinafter referred to as the "foundation structure method") supporting the foundation structure directly below the sliding support, which is integrated with the seismic isolation layer slab, are one of the following. (a) A foundation structure method using a direct foundation in which the foundation body is in direct contact with the supporting ground. (b) A foundation structure method using short pile support in which the foundation body is supported by one or more short piles. (c) A foundation structure method using long pile support in which the foundation body is supported by one or more long piles. (d) A foundation structure method in which the pile types described in (b) and (c) above are cast-in-place concrete piles, various precast concrete piles, various steel pipe piles, steel pipe concrete piles, or connected piles of steel pipe piles and precast concrete piles. (e) A foundation structure method in which, among the foundation structures that employ the pile foundation work, one foundation structure employs one of the pile types described in (d) above, and another foundation structure with a different planar position employs a different pile type described in (d) above. (f) A mixed foundation structure system that combines the different foundation structure systems described in (a) to (e) above.

4. In the seismically isolated building according to claim 3, A seismically isolated building characterized in that a portion of the seismic isolation layer slab in the substructure has been removed, or the seismic isolation layer slab has been completely removed.

5. In the seismically isolated building according to claim 1 or 2, A seismically isolated building characterized in that a portion of the seismic isolation layer slab in the substructure has been removed, or the seismic isolation layer slab has been completely removed.

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