JP6635327B2 - Seismic isolation structure of building and seismic isolation method - Google Patents

Description

  The present invention relates to a seismic isolation structure that reduces the seismic force transmitted to the building side by allowing relative movement between the foundation of the building and the ground during an earthquake. The present invention relates to an origin return means and an origin return method for returning the original position to the original position after the fact, and an improved ground provided with the origin return means.

  With respect to the foundation of a small-scale building such as a detached house, various seismic base structures that are relatively inexpensive and have excellent seismic isolation effects are being studied, and various seismic isolation structures are used at that time. In such a seismic isolation structure, a mechanism is adopted to allow relative movement in the horizontal plane between the building foundation and the ground. (Hereinafter referred to as "sliding seismic isolation mechanism"; see, for example, Patent Documents 1 and 2) and a mechanism using a rotating object such as a ball and a roller (hereinafter referred to as a "rolling seismic isolation mechanism"). For example, refer to Patent Document 3.). In such a seismic isolation structure, after the quake due to the earthquake has settled, in general, the base of the building may be left misaligned with the ground, and it is necessary to provide an origin return means to return this to the original position. preferable. In addition, as a seismic isolation structure, a means for absorbing vibration by using an elastic member such as rubber or a spring directly as a support member is also used. In this case, the elastic member also has a restoration function. In general, it is not necessary to provide the origin return means again.

FIG. 5 is a cross-sectional view showing a part of an improved ground structure provided with a sliding seismic isolation mechanism according to the related art disclosed in Patent Document 1. The improved ground is a ground for laying a foundation 8 of a light-weight building (not shown) such as a detached house made of a wooden structure or a lightweight steel frame, for example. Specifically, the improved ground supporting a vertical load of about 50 kN / m ² or less including the building and the foundation 8 is constructed to reduce seismic force on the foundation 8. In FIG. 5, the improved ground is formed inside the ground 1 that is sectioned by the root cutting portion 11 and excavated according to the desired planar shape of the building. The adjusted ground 2 having a thickness of about 50 to 250 mm is cast on the excavated portion, and the ground portion supporting the building is formed.

  Vibration damping means 4 is provided between the adjustment ground 2 and the foundation 8 as a sliding seismic isolation mechanism, and the relative ground (sliding) between the adjustment ground 2 and the foundation 8 enables vibration. It is to be absorbed. In order to absorb the vibration by sliding, the vibration damping means 4 is composed of a combination of a first sliding member 41 and a second sliding member 42 from below, and the base adjustment sheet 3 disposed below and the upper It is configured to be sandwiched between the vibration isolating rubbers 5 to be arranged. The vibration damping means 4 basically extends over the entire planar projection shape of the building. The seismic force transmitted from the ground 1 to the adjustment ground 2 is absorbed by the sliding between the pair of sliding members 41 and 42 facing each other, and the vibration is transmitted to the foundation 8 and a building (not shown) constructed thereon. To reduce.

  In addition to being able to secure the flatness of the surface, the groundwork adjustment sheet 3 is laid under a building and used for a long time, so that it has high durability and also comes into contact with concrete. A material having high alkali resistance is desired, and as the material, an asphalt sheet, a rubber sheet, a rubber mat and the like can be considered. As an example, as the base adjustment sheet 3, an asphalt sheet having a thickness of 2 to 10 mm is used. The asphalt sheet has a track record as a waterproof sheet on a roof or the like, is excellent in waterproofness, and has an excellent effect of preventing water from entering through the ground 1 and the adjustment ground 2. The loss coefficient (tan δ), which is one of the indexes for evaluating the vibration damping characteristics, is as large as 0.35, and is adopted because it is a preferable material as a vibration-proof material. Alternatively, a rubber-based waterproof sheet may be used.

  A first sliding member 41 is laid on the upper layer of the base adjustment sheet 3. Since the sliding member 41 slides mutually for absorbing vibration between the opposing second sliding member 42, it is indispensable that the sliding member 41 be a material that minimizes the static friction resistance between the two. Condition. Specifically, the coefficient of static friction between the first and second sliding members 41 and 42 is preferably about 0.2, and more preferably 0.15. As a material that can realize this, a fluororesin-based sheet or a superpolymer resin-based sheet can be used.

  As a material of the first sliding member 41, in addition to the material having a low static friction coefficient as described above, a material having heat resistance, chemical resistance, and alkali resistance is preferable. As an example of the first sliding member 41, a fluororesin sheet having a thickness of 0.05 to 2.0 mm, preferably 0.075 to 0.5 mm is used. Since the base adjustment sheet 3 made of an asphalt sheet located in the lower layer has adhesiveness, the fluororesin sheet is adhesively fixed to the base adjustment sheet 3 only by extending on the surface thereof. When a rubber-based waterproof sheet is used as the base adjustment sheet 3, it may be fixed to the first sliding member 41 by being entirely or partially adhered with a double-sided adhesive tape.

  The layer above the first sliding member 41 is basically the reverse of the structure up to now, that is, the second sliding member 42 is opposed to and on the first sliding member 41. In order to ensure a flatness between the base and the foundation 8 constructed of concrete, an anti-vibration rubber 5 is further covered thereon. The concrete of the foundation 8 is cast on the vibration-proof rubber 5, but the procedure thereafter is the same as that of the conventional building. Here, since the vibration is absorbed by the relative sliding between the adjustment ground 2 and the foundation 8, it is preferable that both of them are opposed to each other on the entire surface. "Or a" continuous foundation (cloth foundation) ".

  The second sliding member 42 is developed so as to cover the first sliding member 41. As in the case of the first sliding member 41, as an example of the second sliding member 42, a fluorine resin sheet having a low friction coefficient and a thickness of 0.075 mm is used. As the vibration damping means 4, the arrangement of the fluororesin sheets 41 and 42 is the most preferable combination that can be considered at present from the viewpoint of frictional force. However, there is a problem in terms of cost. It is also possible to replace with a resin sheet. Specifically, an ultrahigh molecular weight polyethylene sheet is considered, and the molecular weight at this time is preferably 1,000,000 or more. By being composed of the above-mentioned materials, the coefficient of static friction between the first sliding member (41) and the second sliding member (42) is set in the range of 0.15 to 0.4. Can be.

Next, on the upper layer of the second sliding member 42, a flat load for supporting a vertical load of a building (not shown) including the foundation 8 and further attenuating the shaking of the vertical and horizontal earthquakes. The vibration rubber 5 is arranged. The material of the vibration-proof rubber 5 may be the same asphalt sheet as the base adjustment sheet 3, but other examples include acid resistance, alkali resistance, water resistance, microbial resistance, oil resistance, and organic solvent resistance. Excellent rubber can be obtained. As an example, it is possible to use a rubber mat (ballast mat) that has a track record of being used as a maintenance-free device under a ballast of a Shinkansen track. This ballast mat is 25 mm thick, 100 mm × 100 mm, and has a vertical panel constant of 4,500 kg / cm. Thus vertical panel constant in ^{m 2} per becomes 450,000kg / cm. Since the load of a standard two-story wooden house is 1 t per m ² , the amount of distortion of 25 mm thickness is about 1/450 = 0.002 cm = 0.02 mm. Therefore, it is preferable to slice a 25 mm ballast mat and adjust the thickness to 2 mm to 10 mm before use.

  Finally, the concrete of the foundation 8 is cast on the rubber cushion 5. When concrete is poured, a special tool for removing air holes inside is vibrated to push or agitate the concrete. Also in such a case, unlike the asphalt sheet, if the rubber mat 5 is pierced, the situation in which the special tool is pierced and collides with the sliding members 41 and 42 is avoided, which is convenient.

  Returning to FIG. 5, a side wall 61 formed by arranging concrete blocks or land blocks or placing concrete is provided on the inner peripheral portion of the root cutting portion 11 in order to prevent collapse of the inner peripheral portion. It may be. Between the base 8 and the side wall 61, a buffer space of about 35 cm to 50 cm is provided as a movement allowance when the base 8 relatively moves, and in this space, the swing of the base 8 in the horizontal direction is buffered. For example, the cushioning material 62 made of a rubber chip having a large particle diameter, preferably 10 to 50 mm is filled. When a rubber chip is filled as the cushioning member 62, the outer peripheral portion of the vibration-proof rubber 5 and the outer peripheral portion of the vibration-proof rubber 5 are prevented so that the rubber chip does not enter between the first sliding member 41 and the second sliding member 42 of the vibration damping means 4. A protective sheet 63 covering the outer peripheral portion of the first sliding member 41 is laid.

  When the cushioning material 62 is filled as described above, the entire layer of the cushioning material 62 is deformed following the horizontal movement and deformation of the vibration isolating rubber 5 and the foundation 8 due to the seismic motion. Since the deformation is not limited, the damping characteristics of the vibration isolating rubber 5 against the shaking can be sufficiently exhibited. The above-described cushioning material 62 is filled up to the height (ground level) corresponding to the ground surface, and the upper ends of the side wall 61 and the cushioning material 62 are made of butyl rubber or the like in order to prevent penetration of rainwater or the like into the ground. It is covered with a waterproof sheet 7 made of rubber or resin such as polyethylene.

  As described above, the improved ground disclosed in Patent Document 1 has a layer in which the adjustment ground 2, the ground adjustment sheet 3, the sheet-shaped vibration damping means 4, and the vibration-proof rubber 5 are sequentially laminated on the root cutting portion 11. Since the structure is provided, and the vibration damping means 4 is disposed so as to correspond to the entire lower surface of the vibration isolating rubber 5, the construction is considered to be simple. Further, in the improved ground, the vibration damping means 4 and the vibration damping rubber 5 are laminated, and the first sliding member 41 and the second sliding member are each made of a fluororesin sheet or an ultra-high-molecular polyethylene sheet. Since the vibration damping means 4 is formed by superimposing 42, the seismic force transmitted from the ground 1 to the foundation 8 during an earthquake can be reduced, and in particular, the horizontal impact force of the earthquake can be significantly reduced.

  As an operation at the time of occurrence of an earthquake, when a horizontal earthquake motion is transmitted from the ground 1 to the adjustment ground 2, the vibration damping means 4 on the upper surface of the ground adjustment sheet 3 causes the acceleration (impact force) to have a predetermined magnitude (for example, For relatively weak shaking that does not reach about 200 gal), both follow the adjustment ground 2 and the ground adjustment sheet 3 and behave together. However, when the acceleration (impact force) of the seismic motion exceeds a predetermined magnitude, the mutual frictional force between the first sliding member 41 and the second sliding member 42 in the vibration damping means 4 is extremely low. The second sliding member 42 to which the load of 8 is applied does not follow the first sliding member 41 which vibrates together with the adjustment ground 2 and the ground adjustment sheet 3 due to its inertia force, and does not vibrate. Move slightly to the center. Furthermore, the vibration-proof rubber 5 to which the load of the foundation 8 is applied reduces the vertical vibration transmitted to the foundation 8 by its own elastic deformation. As a result, it is possible to reduce the impact force of the vertical earthquake on the foundation 8 as described above. In addition, the improved ground is formed by laminating sheet-like and plate-like members, and has no mechanical structure, so that excellent durability can be exhibited.

  Patent Literature 4 discloses an origin return means that can be used for an improved ground as disclosed in Patent Literature 1 described above. The origin return means manually returns the origin of a building in which a displacement has occurred during an earthquake to an origin. It is configured to be. FIG. 6 shows the structure. The origin returning means 30 is composed of a reference mandrel 31 fixed to the ground side and protruding upward, and an adjustment hole 32 formed in the foundation of the building so as to surround it. ing. When the foundation of the building is displaced by the action of the sliding seismic isolation mechanism (reference numeral 10 in FIG. 6), the gap is adjusted by operating a jack (not shown) between the reference mandrel 31 and the adjustment hole 32. Can be made manually. By using the origin return means 30, it is also possible to arrange an elastic member such as a spring between the reference mandrel 31 and the adjustment hole 32 to perform automatic origin return.

  Next, FIG. 7 shows a seismic isolation structure shown in Patent Document 2, which is also configured to allow relative movement of the foundation of the building with respect to the ground by a sliding seismic isolation mechanism. In the figure, a sliding seismic isolation mechanism (reference numeral 5 in FIG. 7; referred to as "sliding means" in the document) is a cement-based hardened material formed with a ceramic coating film as a member constituting a sliding surface. Steel plates, ceramic plates, FRP plates and the like coated with a low friction material such as fluororesin are used. In order to adjust the displacement of the foundation of the building after the earthquake, the seismic isolation structure is a return-to-origin means made of an elastic material such as rubber or thermoplastic elastomer (reference numeral 16 in FIG. 7; referred to as "elastic restoration device" in the document). )). In the event that the base side is displaced, it is intended to return to the original position by the elastic force of the origin return means (16).

  Further, FIG. 8 shows an outline of the rolling seismic isolation structure disclosed in Patent Literature 3. In this case, the X-axis perpendicular to the figure provided separately on the front and back surfaces of a plurality of steel plates (reference numerals 2, 3, and 4) is shown. A large number of rollers (reference numeral 5 in FIG. 8) are arranged in a plurality of grooves in the direction and the Y direction, and the vibration caused by the earthquake is absorbed by the rotation of the rollers in both the X and Y directions to allow movement of the foundation of the building with respect to the ground. are doing. Since the grooves into which the rollers fit are curved, the foundation of the building (reference numeral 6 in FIG. 8; referred to as “seismically isolated structure” in the text) is returned to the original position by the action of gravity. I have.

Japanese Patent No. 4983326 JP 2008-150870 A JP-A-11-351319 JP 2010-059690 A

  However, each of the above-mentioned origin return means has room for improvement. The return means described in Patent Literatures 1 and 4 require manual origin return operation, and the installation of the mechanism is large-scale, which is disadvantageous in cost. In the restoring mechanism described in Patent Literature 2, since the mechanism is installed at least at one location substantially at the center of the building, there is difficulty in handling such as mounting, removing, and maintenance. In the origin return means described in Patent Literature 3, since the relative movement is performed while supporting the load of the entire foundation of the building, high strength is inevitable, and high precision is required for processing and assembling a steel plate having a groove into which a roller fits. However, there were disadvantages in terms of cost, such as the requirement for

  As described above, the present invention solves these problems in the prior art, and facilitates installation, removal, and maintenance, and is also advantageous in terms of cost. It is intended to provide an improved ground with

  The present invention is easy to attach / detach by disposing an origin return means for applying a pulling force or a pressing force between a foundation of a building and a root cutting portion of the ground disposed around the foundation, thereby facilitating attachment and detachment. The present invention solves the above-mentioned problems by providing an origin return means which is also advantageous in terms of the present invention, and specifically includes the following contents.

  That is, one aspect according to the present invention is origin returning means for returning a displacement of a foundation of a building relatively moved to the ground during an earthquake by a seismic isolation structure to an original position, wherein the ground side and the foundation side of the building are provided. Are arranged in a buffer space around the foundation of the building so as to directly or indirectly connect them, and either or both of the pulling force and the pressing force generated in the origin return means due to the displacement are used for the displacement. The present invention relates to an origin returning means characterized by eliminating the above.

  The return-to-origin means can be made of either an elastic material that provides a tensile force or a pressing member that provides a pressing force. In the case of an elastic material, any form of an annular, rod-like, or plate-like rubber material can be used. The rubber material may be a durable rubber material, preferably an ultra-low hardness rubber material. Further, the elastic material may be a plate-like rubber material which covers the periphery of the side surface between the ground side and the foundation side and also serves as a waterproof mechanism.

  Another aspect according to the present invention is an improved ground having a seismic isolation structure that reduces a seismic force by allowing horizontal relative movement between the ground and a foundation of a building during an earthquake. Further comprises origin return means for returning the displacement of the foundation of the building caused by the relative movement to the original position, wherein the origin return means is any of the above-mentioned origin return means. About. The buffer space around the foundation of the building on the improved ground may be filled with a so-called "drainage pipe" formed by cutting a small-diameter pipe material recovered from plastic waste material into a short length as a buffer material.

  Still another aspect according to the present invention is to displace the foundation of a building caused by a base-isolated structure that allows horizontal relative movement between the foundation of the building and the ground during an earthquake to reduce seismic force. A method of returning to the original position, wherein an origin returning means made of an elastic material or a pressing member is provided around the foundation of the building so as to directly or indirectly connect the ground side and the foundation side of the building. The present invention relates to a method of returning to the origin, characterized in that a plurality of the arrangements are arranged in a buffer gap, and the deviation is eliminated by using one or both of a pulling force and a pressing force generated in the origin returning means by the deviation. The origin returning means may use the tensile force of the ultra-low hardness rubber generated by the deviation.

  According to the origin return means according to the present invention, since the buffer space necessary for securing a movement allowance when the base 8 is relatively moved with respect to the ground 1 can be arranged as it is, for example, Japanese Patent Application Laid-Open No. H10-163,089 is disclosed. As compared with the means described in item 4, no additional equipment is required, which is advantageous in cost. In addition, compared to the means described in Patent Document 2, access to the buffer gap is easy, and attachment / detachment of the home position return means becomes easy, so that maintenance can be performed easily. Further, the means described in Patent Document 3 does not require highly accurate groove processing on a curved surface, which is advantageous in cost. These factors make it possible to provide a simpler and less expensive origin return function for the origin return means found in the prior art.

It is the top view (a) and side view sectional view (b) of the improved ground provided with the origin return means concerning an embodiment of the invention. FIG. 2 is a perspective view illustrating a mounting state of the home position return unit illustrated in FIG. 1. FIG. 3 is a perspective view showing an elastic member used in the origin returning means shown in FIG. 2 and an alternative thereof. It is a perspective view of the improved ground provided with the origin return means concerning other embodiments of the present invention. It is a side sectional view showing the improved ground provided with the sliding seismic isolation mechanism concerning a conventional technology. It is a side sectional view (a) and a schematic plan view (b) showing an origin returning means applicable to the improved ground shown in FIG. It is a side sectional view showing other improved ground provided with a sliding seismic isolation mechanism concerning a conventional technology. It is a sectional side view which shows the other improved ground provided with the rolling seismic isolation mechanism which concerns on a prior art.

  With reference to the drawings, a description will be given of an origin returning unit according to a first embodiment of the present invention and an improved ground provided with the origin returning unit. FIGS. 1A and 1B show an outline of an improved ground provided with an origin returning means according to the present embodiment, wherein FIG. 1A is a plan view and FIG. 1B is a side sectional view. In both figures, the improved ground according to the present embodiment basically follows the structure of the improved ground using the sliding seismic isolation mechanism disclosed in Patent Document 1 described in the section of the prior art. In addition to the above, an origin return means 20 described below is further provided. However, the application of the present invention is not limited to the sliding seismic isolation mechanism shown in the drawing, and other seismic isolation that allows relative movement of the foundation with respect to the ground It is also applicable to structures.

  1 (a) and 1 (b), the improved ground is provided with a flat adjusting ground 2 surrounded by a side wall 61 in a root cut portion 11 of the ground 1, on which a foundation is provided via vibration damping means 4. 8 are provided. The foundation 8 is also preferably a flat solid foundation, and a building (not shown) is constructed on the foundation 8. Although the illustration of the base adjustment sheet 3 and the anti-vibration rubber 5 is omitted in the figure for simplicity of explanation, it is of course possible to provide them as in Patent Document 1. The vibration damping means 4 is composed of a first sliding member 41 on the adjustment ground 2 side and a second sliding member 42 on the base 8 which are arranged to face each other. By wrapping it, foreign matter and moisture are prevented from being mixed between the sliding members 41 and 42. The protection sheet 71 is required to have flexibility and elasticity that can follow relative movement between the sliding members 41 and 42 during an earthquake, and in this embodiment, a polyethylene sheet having a thickness of 0.2 mm is used. Another sheet material such as a rubber material may be used. The vibration at the time of the earthquake is absorbed by the sliding (slipping) between the sliding members 41 and 42, and attenuates the vibration transmitted from the ground side to the foundation 8. This structure is the same as that described with reference to Patent Document 1 in the prior art.

  The buffer gap 70, which is a gap between the side wall 61 and the foundation 8, is designed to allow for the movement allowance of the foundation 8 which moves relative to the adjustment ground 2 by sliding during an earthquake, and is generally about 35 cm to 50 cm. Have a width. In the prior art shown in FIG. 5, a buffer material 62 (see FIG. 5) is filled in the buffer space 70, and sand or the like can be used as the buffer material 62 in addition to a rubber chip. Drainage pipes are preferred. Alternatively, the buffer material 62 may be unfilled. In the present embodiment, the origin return means 20 is provided using the buffer gap 70, and a plurality of origin return means 20 are arranged around the foundation 8. By utilizing the space of the buffer gap 70 as it is, the present embodiment has an advantage that special equipment for returning to the origin is not required. The origin returning means 20 connects and connects the base 8 side and the side wall 61 with an elastic material 23 such as rubber. For this reason, mounting tools 21 and 22 are provided on the base 8 side and the side wall 61 side, respectively. In the example shown in the figure, two such home position return means 20 are arranged on each of the four sides of the plane quadrilateral foundation 8, but the number and arrangement thereof will be described later. It can be set appropriately according to the specifications of the vibration damping means 4 and the shape of the foundation 8. For example, if the base 8 is a quadrilateral, it is preferable to arrange at least one or two origin return means 20 on each side in order to restore the displacement of the plane in the two axial directions. Even in such a case, it is preferable that an arrangement according to this is performed. Although the side wall 61 is provided inside the root cutting portion 11 in FIG. 1, the side wall 61 may not be provided in some cases. In such a case, the attachment 22 may be raised vertically from the adjustment ground 2 and the elastic member 23 may be attached thereto.

  FIG. 2 is a perspective view showing a state where the origin returning means 20 is disposed between the foundation 8 and the side wall 61 (the ground 1). In FIG. 2, the origin returning means 20 includes an annular elastic member 23 (hereinafter also referred to as “annular rubber member 23”) and an attachment 21 provided on the base 8 side and an attachment 22 provided on the side wall 61 side. Are fixed by fitting them into the respective parts. For this reason, the attachment and detachment of the annular rubber material 23 becomes extremely easy, and the attachment and detachment of the origin return means 20 and the maintenance are not required. As can be seen from the side sectional view of FIG. 1B, the upper surface of the buffer space 70 is covered with a waterproof cover 73 having appropriate strength, so that access to the origin return means 20 is easy. During an earthquake, the waterproof cover 73 moves integrally with the foundation 8 and does not restrict the relative movement of the foundation 8. Alternatively, as in the prior art shown in FIG. 5, the cushioning space 70 may be filled with a cushioning material 62, in which case the cushioning material 62 may be made of a material that does not hinder access to the origin return means 20, It is preferable to select a material that does not hinder the relative movement of the foundation 8 at the time, for example, a drain pipe. This will be described later.

  FIG. 3 shows a specific example of the shape of the elastic member 23, and FIG. 3A shows an example of the annular rubber member 23 having a predetermined width shown in FIG. FIG. 3B shows an alternative elastic member 23 made of a rod-shaped (or plate-shaped) rubber. In this case, mounting flange members 23a, 23a are attached to both ends in the longitudinal direction by baking or the like, and these portions are inserted and fixed into attachments 21a, 22b provided on the foundation 8 and the side wall 61. These forms are merely examples, and the form of the elastic member 23 and the attaching means can be applied to other forms and countermeasures known in the related art.

  As the rubber material of the elastic member 23, it is desired to select a rubber material having excellent flexibility and shock absorption, and also having excellent strength and weather resistance. Specifically, it is preferable to use an ultra-low hardness rubber, but other rubber materials may be used as long as the conditions are satisfied. Ultra-low hardness rubbers include EPDM, silicone rubber, and butyl rubber, and can be selected depending on the application. As an example, the physical properties of the ultra-low hardness rubber subjected to the test are as follows: hardness (JIS-A): 26, tensile strength: 5.6 MPa, elongation at break: 872%, tensile strength at 100% elongation: 0 .29 MPa, tensile strength at 200% elongation: 0.39 MPa. By appropriately arranging and mounting such elastic members 23 via the mounting members 21 and 22 on both sides facing each other in the buffer space 70 around the foundation 8, when the foundation 8 moves in either direction. At least the elastic member 23 of the home position return means 20 disposed on the pulled side is stretched, and provides a restoring force (pulling force) for returning the base 8 to the home position when it contracts.

As an example in the case of using the elastic material 23 having predetermined dimensions, the required quantity of the origin returning means 20 can be calculated as follows. For example, assuming a two-story building having a building area of 8 m × 8 m, the building load is about 64 tons (1 ton / m ² ) and the mass is 65.3 kg · sec ² / cm (64,000). {980 cm / sec ² ), and this mass is defined as M. At the time of an earthquake, the natural frequency around 0.5 Hz is a killer pulse region (a dangerous frequency region that causes resonance). The aim is to make the frequency about 0.1 Hz. Assuming that the spring constant of the origin return means 20 at that time is K (kg / cm) and the vibration frequency is fr,
fr = 1 / 2π · (K / M) ^1/2
From the relationship, the spring multiplier K is
K = fr ² × 4 × π ² × M = 25.7 kg / cm
Becomes

On the other hand, with reference to FIG. 3A, a ring rubber in the case of using a ring rubber material made of ultra-low hardness rubber having a thickness W = 20 mm, a width S = 100 mm, and a half-fold length L = 300 mm as the elastic member 23. When the tensile spring constant K per material is calculated, the 100% modulus of the ultra-low hardness rubber is 0.29 megapascal (2.9 kg / cm ² ), and the 200% modulus is 3.9 megapascal, as described above. (3.9 kg / cm ² ), the difference in tensile strength at 100% elongation between them is 1.0 kg / cm ² . The tensile force when 100% elongation changes during this period is 2 (cm) × 10 (cm) × 1.0 kg / cm ² × 2 (both sides of the annular rubber material) = 40 kg
Becomes From this, if the tension spring constant K per elastic member 23 made of the annular rubber material when the variation is 300 mm is calculated,
K = 40kg / 30cm ≒ 1.3kg / cm
Becomes

Next, as shown in FIG. 1A, it is assumed that the same number of elastic members 23 (only two are shown on each side in the illustrated example) are arranged on each side around the base 8 having a rectangular shape on a plane. Assuming that the required number A of the elastic members 23 arranged on each side is calculated. Now, assuming that the foundation 8 relatively moves to the left side of the figure during an earthquake, a tensile force is applied to the A elastic members 23 located on the right side of the figure, but the elastic members 23 located on the left side of the figure. Does not act at all because it moves in the loosening direction. On the other hand, a tensile force is obliquely applied to each of the A elastic members 23 located on the two sides of the upper and lower surfaces, and the tensile force at this time is temporarily assumed to be 1/3 of the tensile force acting on the right side. . Thus, the total number of elastic members 23 acting as a tensile force around the foundation 8 is calculated as A + 2 × A ×× = 5/3 · A. Since the above-mentioned spring constant K per one is 1.3 kg / cm,
A = K / K · 3/5 = 25.7 kg / cm / 1.3 kg / cm · 3/5 = 11.9, and the required number A per side is about 12. That is, if twelve annular rubber elastic members 23 are arranged on each side of the rectangular shape of the base 8, the natural frequency of the base 8 (including the building) can be set to 0.1 Hz.

  However, the specifications of the annular rubber and the shape, mass, and the like of the base 8 are merely examples, and the required number of the elastic members 23 naturally differs under different conditions. For example, a rubber-based waterproof sheet such as EPDM is used as the elastic member 23, and the dimensions shown in FIG. 3A are set as follows: thickness W = 1.5 mm, width S = 100 mm, and half-fold length L = 300 mm. Assuming that a set of two annular rubber materials is used, a tensile force at the time of 100% elongation change is 78 kg, and a tensile spring constant per one is 2.6 kg / cm. The required number of elastic members 23 per hit is calculated as 6 sets (12 sheets).

  Returning to FIGS. 1 and 2, in order to avoid an unexpected resonance and to attenuate the continuation of the vibration of the building due to the expansion and contraction of the elastic member 23 at an early stage, the improved ground is moved along the origin returning means 20 as shown in the drawing. Preferably, a damping means 25 such as a damper is provided. In the illustrated example, one damping means 25 is provided in each of two axial directions. However, in order to attenuate vibration in a horizontal plane, at least one damping means 25 is provided along two axes on a plane as described above. However, the number is not limited to this. The damping means 25 may be bolted to the side surface of the base 8 and the side wall 61 via a joint, or may be plugged and fixed as shown in FIG. It may be. The installation of the damping means 25 is similarly applicable to the following embodiment.

  In the example shown in FIG. 1, the origin return means 20 is disposed with the buffer space 70 remaining hollow, but for example, as shown in FIG. Alternatively, the cushioning material 62 may be filled in other portions by dividing only the portion of the origin returning means 20 into a cavity. In the present embodiment, as the cushioning material 62, a large number of small-diameter plastic hollow cylindrical materials called “drainage pipes”, which are used by packing in a nonwoven bag as a material of a “drainage mat”, are used. I have. "Drainage pipe" is a material made by recycling plastic waste materials such as polyethylene into pellets, and by special processing, reclaimed into a hollow cylindrical shape with an outer diameter of about 8 mm, a wall thickness of about 1.5 mm, and a length of about 10 mm. Niigata, Niigata Prefecture Available from Oris Co., Ltd. in the city, Fuji Kasei Kogyo Co., Ltd. in Yonago, Tottori.

  The advantages of using this “drainage pipe” as the cushioning material 62 are that it is advantageous in terms of resources and cost due to the use of waste materials, and when soil, sand and gravel are used as fillers, May act as a brake to hinder the sliding performance of the vibration damping means 10 during an earthquake, whereas the "drainage pipe" does not show this, and a good interference characteristic can be obtained. Also, especially in cold regions, when soil, sand, or gravel is used as a cushioning material, when water enters the interior, it freezes and has a further adverse effect on the slip performance of the damping means. The drainage pipe is excellent in water permeability, so that such adverse effects hardly occur, and even if the drainage pipe itself freezes, it is crushed by a slight shock, so that the buffer characteristics are not significantly impaired. In addition, unlike the soil and the like, the “drainage pipe” itself is an elastic material, so that it is possible to absorb the shock of vibration and to expect a certain degree of return to origin. Compared to the cushioning material 62 made of a rubber chip used in the prior art, since it is a hollow material, flexibility and drainage are enhanced, and particularly, the cushioning property at the time of freezing is excellent. If a waterproof sheet is put on the cushioning material 62 and crushed stones or gravel are further laid thereon, there is no strange feeling in appearance. For example, by setting the thickness (depth) of the cushioning material 62 to 10 cm and the thickness of the crushed stone to 5 cm, it becomes possible to walk normally without a feeling of stepping and fluffy, and at first glance a general building And cannot be distinguished.

As described above, the origin return means 20 according to the first embodiment of the present invention has been described. However, according to the origin return means 20, it is easy to mount, and by selecting the material and the specifications, the foundation by the earthquake can be obtained. 8 and the adjustment ground 2 (ground 1) can be eliminated and the origin can be automatically returned. According to the test results obtained by using the ultra-low hardness rubber having the above-described physical properties and applying an input acceleration of 800 gal and vibrations at frequencies of 5 Hz and 3 Hz, the response acceleration of the base 8 side is reduced to 230 gal in all cases. , And the residual displacement (deviation) was 0 mm. Even if it is not possible to completely return to the original position immediately after the earthquake, the elastic member 23 restores the position even when the sliding member 41 and 42 do not slip between the sliding members 41 and 42 at an acceleration of 200 gal or less. The force acts to return to the origin. In addition to this, it is assumed that a pulling force in the direction of returning to the origin will work as long as the base 8 remains displaced by the intrusion of the living environment caused by a microearthquake that does not feel to the body, a railway running, a large vehicle running, etc. It is possible to achieve the origin return capability by these actions.

  Next, an origin returning unit according to a second embodiment of the present invention and an improved ground provided with the origin returning unit will be described with reference to the drawings. FIG. 4 is a perspective view showing an outline of an improved ground provided with the origin return means 20a according to the present embodiment. In the figure, the improved ground according to the present embodiment basically follows the configuration of the improved ground using the sliding seismic isolation mechanism disclosed in Patent Document 1 or Patent Document 4 described in the section of the prior art. , Which is provided with origin return means 20a. However, the application of the present invention is not limited to the sliding seismic isolation mechanism shown in the drawing, and even if the seismic isolation structure is based on the rolling seismic isolation mechanism, other seismic isolation that allows relative movement of the foundation with respect to the ground It is also applicable to structures.

  In FIG. 4, similarly to the structure disclosed in Patent Literature 1, the improved ground has an adjustment ground 2 placed on the ground 1, and a foundation 8 is further placed thereon via a vibration damping means 4. Is provided. The foundation 8 is also preferably a flat solid foundation, and a building (not shown) is constructed on the foundation 8. Here, the vibration damping means 4 is composed of a first sliding member 41 on the adjustment ground 2 side and a second sliding member 42 on the base 8 side, which are arranged to face each other. Although not shown in FIG. 4 for simplicity of description, these sliding members 41 and 42 may be wrapped in a protective sheet 71 shown in FIG. Further, although not shown in FIG. 4, as in the case of FIG. 1B, the sliding members 41 and 42 may be arranged so as to sandwich the base adjustment sheet 3 and the vibration isolating rubber 5 (see FIG. 5). Of course it is possible.

  In the improved ground shown in the present embodiment, a plate-like elastic material 23a is arranged over both sides of the adjustment ground 2 and the foundation 8 so as to connect the two sides, and the mounting tools 21a, 22b (appropriately arranged in the illustrated example) Are fixed to the foundation 8 side and the adjustment ground 2 side, respectively. If necessary for fixing, a fixing steel plate or the like may be baked on the fixing portion of the elastic member 23a. As the rubber material of the elastic material 23a, it is preferable to use an ultra-low hardness rubber as in the above embodiment, but other rubber materials may be used as long as the conditions are satisfied. In the illustrated example, one such origin return means 20 is disposed on each of the four sides of the flat quadrilateral base 8. However, this quantity and arrangement can be appropriately set according to the weight of the foundation 8 including the building, the specifications of the vibration damping means 4, and the shape of the foundation 8, as described later. For example, if the base 8 is a quadrilateral, it is preferable to arrange at least one or two origin return means 20 on each side in order to restore the displacement of the plane in the two axial directions. Even in such a case, it is preferable that an arrangement according to this is performed.

  Although not shown in FIG. 4, the surroundings of the adjustment ground 2 and the foundation 8 are surrounded by a root cut portion of the ground 1, and the relative position of the base 8 at the time of the earthquake is between the ground cut portion and the root cut portion. As in the previous embodiment, a buffer space 70 (see FIG. 1B) for allowing movement is provided, and the buffer material 62 can be filled in the buffer space 70. However, it is not always necessary to install the side wall 61 provided inside the root cutting portion 11 (refer to FIG. 1).

  The vibration at the time of the earthquake is absorbed by the sliding (slipping) between the sliding members 41 and 42, and attenuates the vibration transmitted from the ground side to the foundation 8. This structure is similar to that described in the prior art. FIG. 4 shows a state in which the improved ground 2 and the foundation 8 have relatively moved in the X direction due to the earthquake, and in this case, the elastic members 23a of the origin returning means 20a arranged on both sides in the X direction have first In contrast to the embodiment, a tensile force is generated on both sides, and a shear force is applied to the elastic member 23a of the origin return means 20a disposed on both sides in the Y direction. Each of the origin return means 20a is disposed in the buffer gap between the root return part, so that attachment / detachment and maintenance can be easily performed as in the previous embodiment.

  As the rubber material of the elastic material 23a, it is desired to select a rubber material having excellent flexibility and shock absorbing properties, and also having excellent strength and weather resistance. It is preferable to use, but other rubber materials may be used as long as the conditions are satisfied. As an example in the case of using the elastic material 23a having predetermined dimensions, the required quantity of the origin returning means 20 can be calculated in the same manner as in the above embodiment. If the conditions such as the building area are the same as those in the previous embodiment (8 m × 8 m, 2 stories, building load is about 64 tons), the killer pulse region near the natural frequency of 0.5 Hz during an earthquake is avoided. If the natural frequency is set to 0.1 Hz, the spring constant K is also set to 25.7 kg / cm.

On the other hand, in FIG. 4, the elastic material 23a is made of ultra-low hardness rubber, the thickness is 5 mm, the width in the vertical direction is 100 mm (movable area), and the length is 1 m. The tensile force when the% elongation changes is 50 kg, and the tensile spring constant per elastic member 23a is about 5 kg / cm. Assuming that the number of elastic members 23a arranged around each of the foundations 8 is A, a tensile force is generated in the elastic members 23a on both sides in the X direction, and the shear force applied to both sides in the Y direction is reduced to 1/3 of the tensile force. Thus, the total number of the elastic members 23a involved when converted to tension is 2A + 2A / 3 = 8/3 · A. From the spring constant K required to avoid the resonance, the spring constant of the elastic member 23a, and the number of the elastic members 23a involved, the required number A of the elastic members 23a required on one side of the foundation 8 is as follows:
A = K / K · 3/8 = 25.7 kg / cm / 5 kg / cm · 3/8 ≒ 2, that is, two plate-like rubber elastic members 23 a are arranged on each side of the rectangular shape of the foundation 8. Then, the natural frequency of the base 8 (including the building) can be set to 0.1 Hz. However, the specifications of the plate-like rubber and the shape and size of the base 8 described above are merely examples, and the number of required rubbers will naturally differ according to different conditions. For example, when a plate-shaped rubber-based waterproof sheet having a thickness of 1.5 mm, a width of 100 mm, and a length of 0.5 m is used as the elastic member 23a, the required quantity for each side of the base 8 is one.

  The processing of the buffer space 70 (see FIG. 1) provided around the adjustment ground 2 and the foundation 8 in the present embodiment may be the same as in the previous embodiment. In addition, the origin return means 20a according to the present embodiment is easy to mount, eliminates the displacement between the foundation 8 and the adjusted ground 2 (ground 1) due to the earthquake by selecting the material and the specifications, and automatically performs the operation. The same effect can be obtained in that it can be returned to the original point, but in addition, it also has the effect of functioning as a waterproof sheet (reference numeral 21 in the document) as shown in Patent Document 4. Can be. That is, from the characteristic that the elastic member 23a is disposed across the adjustment ground 2 and the foundation 8, the elastic member 23a surrounds the periphery of both of them, and the elastic member 23a provides a space between the adjustment ground 2 and the foundation 8. By covering the sliding members 41 and 42, foreign matter and moisture are prevented from being mixed between the two sliding members 41 and 42, and an effect of eliminating a factor that deteriorates sliding resistance for vibration absorption is produced. Becomes

  A number of variations are conceivable for the origin return means according to the present invention. In the examples shown in the above embodiments, rubber (ultra-low hardness rubber) is used as the elastic material 23, but another elastic material such as a coil spring may be used. When rubber is used as the elastic member 23, the restoring force is basically only on the pulling side, but when a spring is used, the restoring force is dispersed because it acts on both the compressing side and the pulling side. be able to. However, this is considered to be disadvantageous for damping the vibration, and it is preferable to additionally provide damping means 25 such as a damper.

  As another modification, a gas-filled damper may be used instead of the elastic member 23. In this case, the restoring force is different from the tensile force in the case of rubber, and the pressing force by the gas-filled damper on the compressed side is used. The gas-filled damper can be easily attached and detached by providing brackets 23a at both ends, such as the elastic member 23 in FIG. 3B, and inserting the brackets 23a and 22a into the fittings 21a, 22a. When the pressing force decreases due to leakage, maintenance is easy. In the present specification, a member that generates a pressing force, such as a gas-filled damper, is referred to as a “pressing member”, while rubber, a spring, and the like are referred to as “elastic materials”. The pressing member is not limited to a telescopic type (telescopic type) such as a gas-filled damper, but may be a bending type (manipulator type) that generates a pressing force by being compressed. Further, the origin returning means 20 made of the elastic material 23 and the origin returning means made of the pressing member may be arranged in a mixture around the base 8.

  Further, in the examples shown in FIG. 2 and other figures, the origin return means 20 is directly fixed to the foundation 8 and the side wall 61 (or the adjustment ground 2), but another method of indirectly fixing may be used. For example, a pantograph-shaped member or an arm-shaped bent member may be arranged between the foundation 8 and the side wall 61, and the displacement may be restored by using the elastic material attached to the elements of these members and the expansion and contraction of the pressing member. Good. This makes it possible to adjust the restoring force and restoring stroke amount of the origin returning means with respect to the magnitude of the amplitude.

  As another application example of the origin returning means 20 according to the first embodiment, in the above description, the displacement caused by the relative movement between the base 8 and the adjustment ground 2 is changed to the origin returning means 20 arranged around the base 8. It was something to use. Using the same origin return means 20, a reference mandrel 31 provided on the adjustment ground side (reference numeral 4 in FIG. 6) and an adjustment hole 32 provided on the foundation (reference numeral 5) as shown in FIG. May be provided between them so that the deviation on the base side is returned to the origin. Around the mandrel 31, return-to-origin means 20 for fitting and fixing the above-mentioned elastic material 23 to a mounting tool provided on the adjustment hole 32 side (foundation side) and a mounting tool provided on the mandrel 31 side (adjustment ground side) are provided. At least three, preferably four or more are arranged, and the displacement is restored by the tensile force of the elastic member 23. In such an example, since the arrangement of the origin return means 20 is indoors, the requirement for weatherability of the elastic member 23 is relaxed, and attachment / detachment is further facilitated. As such an origin return means 20, another elastic adjustment means such as a coil spring as shown in Patent Document 4 may be used.

  INDUSTRIAL APPLICABILITY The origin returning means and the origin returning method according to the present invention, and the improved ground provided with the origin returning means can be widely used in the industrial field for developing, manufacturing, selling, and utilizing a building having a seismic isolation structure. .

1. Ground, 2. 2. adjusting ground; 3. ground adjustment sheet; 4. vibration damping means; 6. Anti-vibration rubber, 7. tarpaulin, Basics, 11. Root cutting, 20, 20a. Origin return means, 21, 22. Fittings, 23. Elastic material (annular rubber material), 23a. 25. Flange member, plate-like elastic material, 30. damping means; Origin return means, 41. 42. first sliding material; 62. second sliding material; Sidewalls, 62. Cushioning material, 70. Buffer void.
73. Waterproof cover,

Claims (7)

Ground, the foundation of the building, a seismic isolation mechanism for reducing seismic force by relative movement between the ground and the foundation of the building during an earthquake, and a displacement of the foundation of the building relative to the ground caused by the relative movement. In the seismic isolation structure of the building including the origin returning means for returning to
The origin return means connects the ground side and the foundation side of the building so that a tensile force is generated along with the relative movement between the two at the time of the earthquake during an earthquake, so that both sides of the ground side and the foundation side are attached via a fixture. seismic isolation structure, characterized in that attached Ri straight set is plural arranged around the foundation of the building, causing a displacement by the relative movement erased solutions using the resulting tensile force to the neutral position restoration means.   The seismic isolation structure according to claim 1, wherein the origin returning means is made of an elastic material, and the elastic material is one of a ring-shaped, a rod-shaped, and a plate-shaped rubber material.   3. The seismic isolation structure according to claim 2, wherein the elastic material is a plate-like rubber material that covers the side surfaces around the ground side and the foundation side and also serves as a waterproof mechanism. 4.   The seismic isolation structure according to claim 2 or 3, wherein the rubber material is an ultra-low hardness rubber material.   In a buffer space provided between the side wall of the ground around the foundation of the building and the foundation of the building, a so-called "drain pipe" formed by cutting a small-diameter pipe material recovered from plastic waste material into a short length is buffered. The seismic isolation structure according to claim 1, wherein the structure is filled as a material. The seismic force is reduced by a seismic isolation mechanism configured to allow horizontal relative movement between the foundation of the building and the ground during an earthquake, and the origin of the displacement of the foundation of the building relative to the ground caused by the relative movement after the earthquake In the seismic isolation method of returning to the original position by the return means,
In order to connect the ground side and the foundation side of the building and generate a tensile force due to the relative movement between the two at the time of an earthquake, the origin returning means made of an elastic material is attached to both the side surfaces of the ground side and the foundation side. seismic isolation method characterized by wearing Ri straight set plurality placed around the building foundation, the erased solutions by utilizing a tensile force generated in the raw position return means a shift by the relative movement through.   The seismic isolation method according to claim 6, wherein the origin returning means uses a tensile force of the ultra-low hardness rubber generated by the displacement.

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