JP2022062510A - Friction damper and base isolation building - Google Patents

Abstract

To provide a friction damper which eliminates a need of high manufacturing accuracy to enable easy manufacturing, installation and construction, achieves effective reduction of shaking of small, medium, and large earthquakes with frictional force which follows displacement, and can suppress excessive displacement with a constant resistance force during a large earthquake while inhibiting increase of an acceleration rate of a base isolation building during a small or medium earthquake.SOLUTION: A friction damper includes: an intermediate steel plate 51 attached to a building; a pair of outer steel plates 52 attached to a basement and disposed so as to overlap with the intermediate steel plate 51 in a plate thickness direction; friction plates 53 which are provided on an inner surface 52a of the outer steel plates 52 and set to multiple friction coefficients along an axial direction; and a slide part 51B which is provided at the intermediate steel plate 51 and contacts with the friction plates 53 to generate frictional force therebetween by axis displacement of the intermediate steel plate 51. The frictional force generated between the friction plates 53 and the slide part 51B during the axis displacement of the intermediate steel plate 51 is set to obtain a first frictional force that increases generally in proportion to the axis displacement and a second frictional force that becomes constant when the axis displacement exceeds a certain level.SELECTED DRAWING: Figure 3

Description

The present invention relates to friction dampers and seismic isolated buildings.

Conventionally, in a general friction damper 100 as shown in FIG. 20, a tightening force (reference numeral T in the figure) is applied from the outer cylinder 101 to the inner cylinder 102, and the relative displacement between the outer cylinder 101 and the inner cylinder 102 is applied. Seismic energy is absorbed by the historical absorption energy due to the frictional force of the contact surface (reference numeral M in the figure). In this case, if the tightening force is constant and the coefficient of friction between the inner cylinder and the outer cylinder is also constant, the restoring force characteristic depends on the increase or decrease in displacement as shown in FIG. 21 (a). The frictional force becomes a constant rectangle.

On the other hand, as a conventional technique, a displacement-dependent friction damper has also been proposed (see, for example, Patent Document 1). As shown in FIG. 21 (b), the restoring force characteristic of the displacement-dependent friction damper is characterized in that the frictional force increases as the displacement increases, and the frictional force becomes small during small and medium-sized earthquakes with small displacement, and the displacement is large. In that case, a large frictional force will be generated. That is, at the time of a small and medium-sized earthquake, the response acceleration of the structure in which the displacement-dependent friction damper is installed in the seismic isolation layer is smaller than the response acceleration of the structure in which the conventional displacement-independent friction damper having the same maximum frictional force is installed. .. On the other hand, in the event of a large earthquake, the response displacement and response acceleration of the structure equipped with the displacement-dependent friction damper become equivalent to the response displacement and response acceleration of the conventional structure equipped with the displacement-independent friction damper.
As such a displacement-dependent friction damper, an inclined sliding bearing and a vertical displacement-dependent friction damper 110 as shown in FIG. 22 are installed in the seismic isolation layer, and the amount of damping is adjusted according to the magnitude of the displacement of the seismic isolation layer. A variable seismic isolation system has been proposed. This seismic isolation system is based on the principle that the vertical displacement increases as the horizontal displacement of the inclined sliding bearing increases.

Jitsukaisho 63-178642 Gazette

However, the conventional seismic isolation system equipped with a tilt bearing and a vertical displacement-dependent friction damper in the seismic isolation layer has the following problems.
That is, for example, when the inclined slope of the inclined sliding bearing is about 0.026 (= tan1.5 °) and the horizontal displacement is 500 mm, the vertical displacement is only 13 mm, and the vertical displacement (0 mm to 13 mm) is small. High followability with high damping force is required during changes. Therefore, in the manufacture of vertical displacement-dependent friction dampers, it is required to suppress material variations with high accuracy, and in construction, it is required to install horizontally with high accuracy, and there is room for improvement in that respect. rice field.

In addition, regarding the installation position of the vertical displacement dependent friction damper, when installing it between the upper part of the seismic isolation structure and the non-seismic isolation structure, it is sufficiently horizontal for the upper structure and the lower structure where the damper is installed. Rigidity is required. If this horizontal rigidity is insufficient, a vertical displacement proportional to the horizontal displacement of the seismic isolation layer cannot be obtained, and there is a problem that the effect of the displacement-dependent friction damper cannot be exhibited.
In addition, when installing at the bottom of the seismic isolation structure, the friction damper is supported by a member extended from the structure in a cantilever form, so the seismic isolation structure is more than when it is installed at the top of the seismic isolation structure. Due to the lack of vertical rigidity and elastic displacement of the installation position member, it is difficult to demonstrate the effect of the vertical displacement-dependent friction damper. Therefore, it was necessary to provide a seismic isolation clearance about twice the clearance required for horizontal movement.

Further, the displacement-dependent friction damper described in Patent Document 1 described above is intended to change the frictional resistance force according to the distance from the neutral axis by attaching a friction material on the inner surface of the cylinder. .. However, when the contact plate is cylindrical, the contact plate cannot be pressed against the inner surface of the cylinder by a wedge, so that the contact plate is divided in the circumferential direction. However, when the contact plate is divided, the contact plate rotates due to frictional force, so that the contact surface pressure with the inner surface of the cylinder cannot be kept constant. Therefore, the frictional resistance force is not exhibited as planned, and the friction material may be damaged in a place where the surface pressure becomes excessive.
Further, in Patent Document 1, since the wedge is pressed by a spring, it is necessary to apply a preload equal to or greater than the frictional force of the damper to the spring. That is, when it is not possible to apply a preload to the spring that exceeds the frictional force of the damper, the force acting on the wedge changes depending on whether a tensile force is applied to the rod of the friction damper or a compressive force is applied, resulting in friction. The surface pressure of the material changes and the frictional force also differs depending on the positive and negative axial forces. Since the preload is given by compressing the spring in advance, it cannot be adjusted after assembly, and high dimensional accuracy including wedges and contact plates is required, and it is necessary to control the inner diameter of the friction material attached to the inner surface of the cylinder with high accuracy. There is. Therefore, there is a problem that it is difficult to adopt this form because the cost increases.

The present invention has been made in view of the above-mentioned problems, does not require high manufacturing accuracy, is easy to manufacture and install, and is effective in shaking with frictional force that follows displacement from small to medium-sized earthquakes to large earthquakes. The purpose is to provide friction dampers and seismic isolated buildings that can suppress the increase in acceleration of seismic isolated buildings during small and medium-sized earthquakes, while suppressing excessive displacement by a certain resistance force during large earthquakes. And.

In order to achieve the above object, the friction damper according to the present invention is connected to a lower structure and an upper structure that is relatively movable with respect to the lower structure, and the axial direction is directed to the horizontal direction. An axial displacement-dependent friction damper to be arranged, the first steel plate attached to the upper structure and the first steel plate attached to the lower structure in the plate thickness direction orthogonal to the axial direction. Friction set to a plurality of friction coefficients along the axial direction by providing the second steel plate arranged so as to overlap and one of the first steel plate and the second steel plate on the surface facing the other side. The material is provided with a sliding portion provided on the other side and in contact with the friction material by generating a frictional force due to the relative displacement of the first steel plate and the second steel plate in the horizontal direction. The frictional force generated between the friction material and the sliding portion when the 1st steel plate and the 2nd steel plate are axially displaced in the axial direction is the first frictional force that increases substantially in proportion to the axial displacement. It is characterized in that it is set to obtain a second frictional force that becomes constant when a certain axial displacement is exceeded.

Further, the seismic isolated building according to the present invention is a seismic isolated building provided with the above-mentioned friction damper, and is an upper structure that is attached to the friction damper and is relatively movable with respect to the lower structure. It is characterized by being provided with an inclined sliding support that supports the superstructure so that the amount of movement in the vertical direction increases as the amount of displacement in the horizontal direction increases.

In the present invention, the frictional force generated between the friction material and the sliding portion when the first steel plate and the second steel plate are axially displaced in the axial direction (horizontal direction) increases substantially in proportion to the axial displacement. Since it is set to obtain one friction force and a second friction force that becomes constant when a certain shaft displacement is exceeded, a shaft displacement-dependent friction damper that increases the friction force as the shaft displacement increases is realized. can do. That is, the friction damper of the present invention can have a displacement-dependent historical characteristic by using a friction material in which a plurality of friction coefficients are combined instead of a physical gradient or the like.
Therefore, when a large earthquake occurs, the resistance is kept constant when a certain displacement is exceeded, so that it becomes fail-safe, and not only excessive displacement but also damage due to acceleration can be suppressed. Further, since the residual displacement of the inclined sliding bearing hardly occurs even in the long-period ground motion, it can be continuously used immediately even after the earthquake.

Further, in the present invention, since the friction damper is a horizontal axis displacement resistance type damper member, it is not necessary to suppress high manufacturing accuracy and variation in manufacturing materials as in the case of a vertical displacement dependent friction damper, and it is easy to manufacture. There is. Since the bolt that applies the compressive force to the friction material is tightened from the outside of the steel plate, it is easy to adjust the frictional force after assembling the friction damper.

Since the friction damper according to the present invention is a shaft resistance type damper, the friction resistance force does not change due to its own weight unlike the sliding bearing. Therefore, the frictional resistance force can be arbitrarily set in each of the two directions, the horizontal axial direction and the direction orthogonal to the axial direction.
Furthermore, since the friction damper is a horizontal axis displacement resistance type damper, it can be installed in the seismic isolation layer at the bottom of the seismic isolation structure, and there is no need to install it at the top of the seismic isolation structure, resulting in a simple structure. can.

Further, in the present invention, by combining a friction damper that does not depend on the vertical displacement of the superstructure and a tilted sliding bearing, it is possible to realize a seismic isolated building that is not affected by the type of seismic wave and can obtain a high seismic isolation effect. In particular, for long-period ground motion, both response acceleration and response displacement can be reduced compared to conventional natural rubber (laminated rubber) bearings, which is more effective than conventional seismic isolation.

Further, in the seismic isolated building according to the present invention, the friction material is set so that the friction coefficient increases as the friction material moves away from the central portion in the axial direction on both sides in the axial direction, and the axial displacement on which no seismic force acts. It is preferable that the sliding portion when becomes 0 is arranged so as to be the central portion of the friction material.

According to the friction damper and the seismic isolated building of the present invention, high manufacturing accuracy is not required, manufacturing and installation work are easy, and shaking is effectively reduced by the frictional force that follows the displacement from small and medium-sized earthquakes to large earthquakes. In the case of a small and medium-sized earthquake, it is possible to suppress the increase in acceleration of the seismic isolated building, and in the case of a large earthquake, it is possible to suppress the excessive displacement by a certain resistance force.

It is a schematic diagram which shows the structure of the seismic isolation building provided with the friction damper and the inclined sliding bearing by embodiment of this invention. It is a figure which shows the structure of the inclined sliding bearing, (a) is an enlarged view of the inclined sliding bearing shown in FIG. 1, and (b) is a view seen from the axial direction. It is a side view which shows the structure of the friction damper shown in FIG. It is a top view of the outer steel plate. FIG. 3 is a view taken along the line AA shown in FIG. 3 and is a plan view of the friction damper as viewed from the friction material side. It is a figure which shows the end processing state of a friction damper, (a) is a figure of a friction plate, (b) is a figure of a sliding part of a middle plate. (A) to (f) are side views showing each stage of the friction damper. It is a figure which shows the restoring force characteristic of a friction damper, and is the figure which shows the relationship between the tightening force and the shaft displacement. It is a figure which shows the restoring force characteristic of a friction damper, and is the figure which shows the relationship between the friction coefficient and the shaft displacement. It is a figure which shows the restoring force characteristic of a friction damper, and is the figure which shows the relationship between the tightening force and the shaft displacement (showing each stage). (A) and (b) are diagrams showing an analysis model according to an example. It is a restoring force figure of the friction damper by an Example. (A) to (c) are diagrams showing a seismic wave diagram according to an embodiment. (A) to (c) are diagrams showing the analysis results of the example cases in the notification Kobe wave. (A) to (c) are diagrams showing the analysis results of the comparative example cases in the notification Kobe wave. (A) to (c) are diagrams showing the analysis results of the example cases in the notification Kanto wave. (A) to (c) are diagrams showing the analysis results of the comparative example cases in the notification Kanto wave. (A) to (c) are diagrams showing the analysis results of the example cases in the notification Hachinohe wave. (A) to (c) are diagrams showing the analysis results of the comparative example cases in the notification Hachinohe wave. It is a figure which shows the structure of the conventional friction damper. It is a figure which shows the conventional restoring force characteristic, (a) is a figure of a friction damper, (b) is a figure of a displacement dependent damper. It is a figure which shows the structure of the conventional vertical displacement dependent type friction damper.

Hereinafter, the friction damper and the seismic isolated building according to the embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the seismic isolated building 1 according to the present embodiment includes a building 20 (superstructure) to be seismically isolated and a seismic isolation system 3 for seismically isolating the building 20.
The building 20 includes a structure to be seismically isolated and a foundation 21 (substructure) that supports the structure. The seismic isolation system 3 includes an inclined sliding bearing 4 that supports the lower part of the building 20 and a shaft displacement type friction damper 5.

The building 20 is formed in a box shape. The building 20 is an upper structure formed separately from the foundation 21 which is a lower structure. The building 20 may be a floor for one floor, or may have a plurality of floors inside. The building 20 is movably supported with respect to the foundation 21 via an inclined sliding bearing 4 and a shaft displacement type friction damper 5.

The foundation 21 is a substructure made of, for example, reinforced concrete, which is constructed on the ground side. The foundation 21 is displaced in conjunction with the ground during an earthquake. The foundation 21 is formed with a base that supports the building 20 from below.

Next, the configuration of the inclined sliding bearing 4 of the seismic isolation system 3 will be described.
As shown in FIG. 1, the inclined sliding bearing 4 is a seismic isolation mechanism that can flexibly displace the building 20 in the horizontal direction while supporting the building 20 in the vertical direction. The inclined sliding bearing 4 supports the building 20 so that the amount of movement in the vertical direction increases as the amount of movement in the horizontal direction of the building 20 that is relatively movable with respect to the foundation 21 provided on the ground increases. do.
The inclined sliding bearing 4 is provided between the foundation 21 and the building 20. Between the foundation 21 and the building 20, for example, four inclined sliding bearings 4 (only one is shown in FIG. 1) are provided to support the four corners of the building 20. In addition, four or more inclined sliding bearings 4 may be provided.

As shown in FIGS. 1 and 2 (a) and 2 (b), the inclined sliding bearing 4 includes, for example, a lower inclined support member 4A provided on the foundation 21 via a support portion 24 and a bottom surface of the building 20. It includes an upper inclined support member 4B fixed to 20a, and a moving member 4C provided between the lower inclined support member 4A and the upper inclined support member 4B.
The lower inclined support member 4A and the upper inclined support member 4B are each formed in a rod shape having a rectangular cross section, and are arranged so that the longitudinal directions are orthogonal to each other in a plan view. The foundation 21 and the building 20 are constructed so as to be relatively movable in the horizontal direction via the inclined sliding bearing 4. The foundation 21 and the bottom surface 20a of the building 20 are displaced upward in the vertical direction according to the amount of displacement of the relative displacement in the horizontal direction.

The lower inclined support member 4A is arranged in the longitudinal direction along one side of the building 20. The lower inclined support member 4A is formed with V-shaped first inclined surfaces 4a and 4a that are inclined so as to jump upward from the center of the upper surface toward both ends when viewed from the side orthogonal to the longitudinal direction. ing. The inclination angle θ of the first inclined surface 4a with respect to the horizontal plane is formed so that the absolute value becomes a predetermined value. The surface of the first inclined surface 4a is coated with a resin-made sliding material such as Polytetrafluoroethylene (PTFE), so-called Teflon (registered trademark), for reducing the coefficient of friction. A sliding material such as a stainless steel plate may be attached to the surface of the first inclined surface 4a.

A moving member 4C is placed on the first inclined surface 4a. The moving member 4C is formed in a block shape. As shown in FIG. 2A, the moving member 4C is formed so as to have a wider width than the lower inclined support member 4A when viewed from the lateral direction of the lower inclined support member 4A. A step is formed below the moving member 4C so that the lower inclined support member 4A is sandwiched and fitted in the width direction when viewed from the lateral direction of the lower inclined support member 4A.

As shown in FIG. 2B, the moving member 4C is formed with V-shaped third inclined surfaces 4c and 4c so as to project downward toward the center in the step. A sliding material such as Teflon for reducing the coefficient of friction is attached to the surface of the third inclined surface 4c. The inclination angle θ of the third inclined surface 4c with respect to the horizontal plane is formed so that the absolute value becomes a predetermined value. The third inclined surface 4c is in contact with the first inclined surface 4a.

The moving member 4C is formed so as to have a wider width than the upper inclined support member 4B when viewed from the lateral side of the upper inclined support member 4B. A step is formed above the moving member 4C so that the upper inclined support member 4B is sandwiched and fitted in the width direction when viewed from the lateral direction of the upper inclined support member 4B.
As shown in FIG. 2A, the moving member 4C is formed with inverted V-shaped fourth inclined surfaces 4d and 4d so as to project upward toward the center in the step. A sliding material such as Teflon for reducing the coefficient of friction is attached to the surface of the fourth inclined surface 4d. The inclination angle θ of the fourth inclined surface 4d with respect to the horizontal plane is formed so that the absolute value becomes a predetermined value. The fourth inclined surface 4d is in contact with the second inclined surface 4b.

As shown in FIG. 2A, the upper inclined support member 4B has an inverted V shape that is inclined so as to be inclined downward from the center of the lower surface toward both ends when viewed from the side in a direction orthogonal to the longitudinal direction. The second inclined surfaces 4b and 4b are formed. The inclination angles θ of the second inclined surface 4b and the fourth inclined surface 4d with respect to the horizontal plane are formed so that their absolute values are predetermined values.

The surface of the second inclined surface 4b is coated with a sliding material such as Teflon to reduce the coefficient of friction. In addition to the coating process, a sliding material such as a stainless steel plate may be attached to the surface of the second inclined surface 4b. A moving member 4C is arranged below the second inclined surface 4b, and the moving member 4C is in contact with the second inclined surface 4b.

Next, the configuration of the shaft displacement type friction damper 5 will be described in detail with reference to the drawings.
As shown in FIG. 1, the friction damper 5 has a frictional force that increases substantially in proportion to the displacement by setting a plurality of friction coefficients in the axial direction X with the building 20, and a constant frictional force that exceeds a constant displacement. It has a function of obtaining a force, and constitutes a restoring force shown in FIG. 8 described later.

As shown in FIGS. 3 to 5, the friction damper 5 includes an intermediate steel plate 51 (first steel plate) and a pair of outer steel plates 52 and 52 (second steel plate) provided so as to sandwich the intermediate steel plate 51 from both sides. A friction plate 53 (friction material) provided on the inner surface 52a of the pair of outer steel plates 52 and 52 facing the intermediate steel plate 51 side is provided. The pair of outer steel plates 52, 52 and the intermediate steel plate 51 are steel plates whose thickness does not change in the axial direction X, and are arranged in a state where their respective plate surfaces are parallel to each other in the horizontal direction.
As shown in FIG. 1, the intermediate steel plate 51 is fixed to the bottom surface 20a of the building 20 via the first support portion 22. The pair of outer steel plates 52, 52 are fixed to the foundation 21 via the second support portion 23.

As shown in FIG. 3, a plurality of bolt holes 52c (see FIG. 4) penetrating in the plate thickness direction Z are provided on both sides in the width direction Y and one of the axial directions X in the outer peripheral portion of the outer steel plate 52. .. The pair of outer steel plates 52, 52 are fixed by a plurality of high-strength bolts 54. Each bolt hole 52c of the pair of outer steel plates 52 is penetrated from one side, and the other is screwed with a nut to be tightened. Further, a plurality of disc springs 56 are inserted through the high-strength bolt 54 so as to be coaxial with the bolt shaft. By this disc spring 56, the friction plate 53 and the sliding portion 51B (described later) of the intermediate steel plate 51 can be set to have a predetermined frictional force. The high-strength bolt 54 and the disc spring 56 can apply a tightening load in the plate thickness direction Z in the friction damper 5.
The pair of outer steel plates 52, 52 has a friction plate 53 having a plurality of friction coefficients installed on the inner surface 52a of each.

The intermediate steel plate 51 is slidably provided in the axial direction X (horizontal direction) in the gap S between the pair of outer steel plates 52, 52. The intermediate steel plate 51 has a steel plate portion 51A extending in the axial direction X and a sliding portion 51B provided at one end of the steel plate portion 51A in the length direction.
The thickness of the steel plate portion 51A is set smaller than the height dimension of the gap S so that a gap is formed between the steel plate portion 51A and the upper and lower friction plates 53. The intermediate steel plate 51 slides in the horizontal direction relative to the pair of outer steel plates 52, 52 in conjunction with the horizontal movement of the building 20.

The sliding portion 51B is formed in a protruding shape protruding outward in the plate thickness direction Z from the steel plate portion 51A, and is a contact portion between the intermediate steel plate 51 and the outer steel plate 52, and is a portion where frictional force is generated.
In the gap S, the sliding portion 51B is provided in contact with the friction plate 53 provided on the outer steel plate 52. That is, the intermediate steel plate 51 slides relatively parallel to the pair of outer steel plates 52, 52 in the axial direction X, so that the upper and lower friction surfaces 51a of the sliding portion 51B are in contact with the friction plate 53. Sliding.

The intermediate steel plate 51 may be slid within the range of the long holes by forming an elongated hole (not shown) at the through portion of each high-strength bolt 54 in the intermediate steel plate 51.

As shown in FIG. 6B, the sliding portion 51B of the intermediate steel plate 51 is chamfered and R-processed on the four corner portions 51b viewed from the side. That is, the chamfered corner portion 51b is a corner portion at a position orthogonal to the sliding direction (axial direction X) when viewed from above. In this way, by forming the corner portion 51b of the sliding portion 51B into a chamfered cross-sectional shape, the sliding portion 51B is displaced due to friction with the friction surface 53a (see FIG. 6A) of the friction plate 53. It is also possible to prevent the surface pressure from changing.

As shown in FIG. 3, between the pair of outer steel plates 52, 52, a high-strength bolt 54 (this high-strength bolt is referred to as an axial movement restricting bolt 54A) for fixing one end in the axial direction X is inserted. A restraint steel plate 55 that restricts the movement of the outer steel plates 52 and 52 in the axial direction X is fixed. The restraint steel plate 55 is formed in a plate shape and is arranged in a gap S between the pair of outer steel plates 52, 52. As shown in FIG. 1, one end 55a of the restraint steel plate 55 is fixed to the shaft movement restricting bolt 54A, and the other end 55b is fixed to the second support portion 23.

As the material of the friction plate 53, for example, a stainless steel plate can be adopted.

As shown in FIG. 6A, the friction plate 53 is chamfered and rounded at a corner portion 53b orthogonal to the axial direction X of the friction surface 53a when viewed from the side. By forming the corner portion 53b of the friction plate 53 into a chamfered cross-sectional shape in this way, it is set so that the surface pressure does not change even if the friction plate 53 is displaced due to friction with the sliding portion 51B of the intermediate steel plate 51. Has been done.

As shown in FIG. 5, in the friction plate 53, a plurality of friction plates 53A to 53F (11 in the present embodiment) having different friction coefficients along the axial direction X are arranged. These friction plates 53A to 53F are manufactured so as to have a predetermined friction coefficient μ (μ0, μ1, μ2, μ3, μ4, μm) by different surface treatment methods. For example, as an example of the friction coefficient μ by surface treatment, it becomes 0.2 (μ1) in the processing by mirror finishing, 0.3 (μ2) in the blasting by small spheres, and 0.4 (μ3) in the blasting by medium spheres. The value is 0.5 (μ4) for blasting with a large ball and 0.6 (μm) for processing with aluminum spraying. The coefficient of friction μ0 is in a state where the surface has not been treated.

In the arrangement of these friction plates 53A to 53K, a first friction plate 53A having a friction coefficient μ0 is arranged in the center in the axial direction X, and the friction coefficient increases as the first friction plate 53A is separated from both sides in the axial direction X. The second friction plate 53B of μ1, the third friction plate 53C of friction coefficient μ2, the fourth friction plate 53D of friction coefficient μ3, the fifth friction plate 53E of friction coefficient μ4, and the sixth friction plate 53F of friction coefficient μ5 are in that order. It is arranged in.
The sliding portion 51B of the intermediate steel plate 51 is located at a position where the axial displacement on which no seismic force acts is 0 (initial position P1 shown in FIG. 7A), and is located at the center of the axial direction X where the first friction plate 53A is arranged. positioned.

The width dimension h0 (see FIG. 5) of the first friction plate 53A to the fifth friction plate 53E in the axial direction X is equal to the effective width dimension H0 extending in the axial direction X of the sliding portion 51B (see FIG. 6B). I am doing it. Further, the width dimension of the sixth friction plate 53F is set to be equal to or larger than the effective width dimension H0 (same for the width dimension h0) of the sliding portion 51B (≧ h0). The width dimension of the second friction plate 53B to the fifth friction plate 53E may be set smaller than h0.

7 (a) to 7 (f) show changes in the frictional force F (friction coefficient μ).
As shown in FIG. 7A, the axial displacement δ of the sliding portion 51B is 0, which is the initial position P1, and the position P2, which is the maximum displacement of the sliding portion 51B shown in FIG. 7D, has an axial displacement δ of μm. It becomes. FIG. 7A shows a stage in which the friction coefficient is μ0 and there is no initial displacement such that the friction force is F0 = μ0 × N (tightening force). FIG. 7B shows a stage where displacement occurs (0 <axial displacement δ <δd). FIG. 7 (c) shows the stage where the displacement occurs (δd <axial displacement δ <δm). FIG. 7D shows a stage (δm <axial displacement δ <δu) in which a large displacement occurs. FIG. 7 (e) shows a stage (−δd <axial displacement δ <0) at which a displacement occurs on the negative side. FIG. 7 (f) shows the stage of maximum displacement (−δu <axial displacement δ <−δm) on the negative side.
Here, δd is a design displacement and is a target value of the axial displacement. δm is the maximum response displacement of the axial displacement. δu is the limit displacement.

From the above, the optimum design method using the shaft displacement-dependent friction damper 5 is as follows.
FIG. 8 shows the restoring force of the axial displacement type friction damper 5 having the above-described configuration.
FIG. 8 shows the relationship between the tightening force N and the axial displacement δ. Here, the tightening force N is constant regardless of the magnitude of the axial displacement δ.
FIG. 9 shows the relationship between the friction coefficient μ and the axial displacement δ. The axial displacement δ is approximately proportional to the friction coefficient μ from 0 to δm. When it exceeds δm, the coefficient of friction μ is kept constant.
FIG. 10 shows the relationship between the frictional force F and the axial displacement δ. Here, (1) to (6) shown in the graph of FIG. 10 show the respective states (1) to (6) of FIGS. 7 (a) to 7 (f).
Due to the relationship between the tightening force N and the shaft displacement δ shown in FIG. 8 and the relationship between the friction coefficient μ and the shaft displacement δ shown in FIG. 9, when the shaft displacement δ is 0 to δm, it is roughly proportional to the increase in the shaft displacement δ. As a result, the frictional force F (hereinafter referred to as the first frictional force) increases. When the axial displacement exceeds δm, the frictional force (hereinafter referred to as the second frictional force) is made constant as a fail-safe of the device. Further, when the frictional force becomes a constant value, the exciting force also reaches a plateau, and the increase in acceleration of the structure is suppressed.

The frictional force F can be expressed by the equation of frictional force F = friction coefficient μ × tightening force N. Since the tightening force N is constant, the relationship between the friction force F and the shaft displacement δ has the same shape as the relationship diagram between the friction coefficient μ and the shaft displacement δ.
In FIGS. 8 to 10, δd is a design displacement and is a target value of the axial displacement. δm is the maximum response displacement of the axial displacement, and is δd × 1.1. δu is the limit displacement, and the design displacement δd × 1.2. However, δu ≧ δm + h0. F0 is the initial frictional force, which is 4 to 6% of the frictional force having the maximum response displacement δm. The initial frictional force Fi is 25% of the frictional force F50 at a shaft displacement of ₅₀ cm.

Next, the operation of the seismic isolated building 1 and the friction damper 5 described above will be described in detail with reference to the drawings.
First, the operation of the inclined sliding bearing 4 of the seismic isolated building 1 will be described.
In the following description, the direction along the axial direction X shown in FIG. 1 is referred to as the x-axis direction, and the direction along the width direction Y shown in FIG. 1 is referred to as the y-axis direction.

As shown in FIG. 1, when an earthquake occurs, the foundation 21 moves horizontally, the building 20 tries to stay in place due to inertia, and the relative horizontal direction between the building 20 and the foundation 21. Displacement occurs. At this time, when the upper inclined support member 4B is displaced in the y-axis direction in conjunction with the displacement of the building 20 in the y-axis direction, the upper inclined support member 4B is hooked on the step and the moving member 4C is y with the upper inclined support member 4B. Move in the axial direction. At this time, as shown in FIG. 2B, in the moving member 4C, the third inclined surface 4c slides with respect to the first inclined surface 4a of the lower inclined support member 4A and moves in the direction of climbing the ascending slope. do.

When the horizontal displacement is in the opposite direction, the moving member 4C moves in the direction in which the third inclined surface 4c slides with respect to the first inclined surface 4a of the lower inclined support member 4A and goes up the ascending slope. Along with this, the upper inclined support member 4B mounted on the moving member 4C is displaced upward in the vertical direction.

Further, when the upper inclined support member 4B is displaced in the x-axis direction in conjunction with the displacement of the building 20 in the x-axis direction, the second inclined surface 4b of the upper inclined support member 4B moves as shown in FIG. 2A. It slides on the fourth inclined surface 4d of the member 4C and moves in the x-axis direction in the direction of climbing the ascending slope.

When the horizontal displacement is in the opposite direction and the upper inclined support member 4B is displaced in the x-axis direction in conjunction with the displacement of the building 20 in the x-axis direction, the second inclined surface 4b of the upper inclined support member 4B becomes the first moving member 4C. 4 Slides the inclined surface 4d and moves in the x-axis direction in the direction of climbing the ascending slope. In the moving member 4C, the lower inclined support member 4A is hooked on the step and moves relative to the upper inclined support member 4B together with the lower inclined support member 4A.

When the building 20 moves in the horizontal direction, the operation of the inclined sliding bearing 4 causes a vertical displacement upward according to the amount of movement in the horizontal direction. The potential energy of the building 20 increases according to the amount of vertical displacement of the building 20. A restoring force that tries to return to the original position by the action of gravity acting on the building 20 displaced upward in the vertical direction acts on the building 20 in the vertical direction.

Then, a force acts on the moving member 4C to slide on the first inclined surface 4a of the lower inclined support member 4A and return to the central portion of the lower inclined support member 4A. Similarly, a force acts on the moving member 4C to slide on the second inclined surface 4b of the upper inclined support member 4B and return to the central portion of the lower inclined support member 4A. Due to the operation of the inclined sliding bearing 4 described above, when a horizontal displacement occurs, a restoring force is generated and the building 20 returns to the original position.

Next, the operation of the friction damper 5 will be described.
As shown in FIGS. 1, 3 to 5, when the building 20 moves in the horizontal direction, the intermediate steel plate 51 of the friction damper 5 moves in conjunction with the building 20. The sliding portion 51B of the intermediate steel plate 51 slides on the surface of the friction plate 53 (friction surface 53a) in conjunction with the horizontal movement of the building 20. As a result, the intermediate steel plate 51 causes frictional resistance generated between the sliding portion 51B and the friction plate 53 according to the amount of movement of the building 20 in the horizontal direction.

At this time, in the friction plate 53 of the friction damper 5, a plurality of friction coefficients μ are arranged so that the friction coefficient μ increases in the direction in which the displacement amount of the sliding portion 51B increases. Therefore, as the axial displacement increases, the frictional resistance between the sliding portion 51B and the friction plate 53 increases. As a result, the friction damper 5 functions as a seismic isolation damper in which the damping force increases as the displacement between the building 20 and the foundation 21 increases.

Next, the actions of the friction damper 5 and the seismic isolated building 1 described above will be described in detail with reference to the drawings.
In the present embodiment, as shown in FIGS. 3 and 5, the friction plate 53 and the sliding portion 51B when the intermediate steel plate 51 and the pair of outer steel plates 52 and 52 are axially displaced in the axial direction X (horizontal direction). Since the frictional force generated between the two is set to obtain a first frictional force that increases substantially in proportion to the shaft displacement and a second frictional force that becomes constant when a certain shaft displacement is exceeded, the shaft is set. It is possible to realize a shaft displacement-dependent friction damper 5 in which the frictional force increases as the displacement increases. That is, the friction damper 5 of the present embodiment can have a displacement-dependent history characteristic by using a friction plate 53 in which a plurality of friction coefficients are combined instead of a physical gradient or the like.
Therefore, when a large earthquake occurs, the resistance is kept constant when a certain displacement is exceeded, so that it becomes fail-safe, and not only excessive displacement but also damage due to acceleration can be suppressed. Further, since the residual displacement of the inclined sliding bearing hardly occurs even in the long-period ground motion, it can be continuously used immediately even after the earthquake.

Further, in the present embodiment, since the friction damper 5 is a horizontal axis displacement resistance type damper member, it is easy to manufacture without the need for high manufacturing accuracy and suppression of variation in manufacturing materials unlike the vertical displacement dependent type friction damper. There is an effect.

Since the friction damper 5 according to the present embodiment is a shaft resistance type damper, it has a structure in which the friction resistance force does not change due to its own weight unlike the sliding bearing. Therefore, the frictional resistance force can be arbitrarily set in each of the two directions, the horizontal axial direction and the direction orthogonal to the axial direction.
Further, since the friction damper 5 is a horizontal axis displacement resistance type damper, it can be installed in the seismic isolation layer at the lower part of the seismic isolation structure, and there is no need to install it on the upper part of the seismic isolation structure, which is a simple structure. Can be done.

Further, in the seismic isolated building 1 according to the present embodiment, by combining the friction damper 5 which does not depend on the vertical displacement of the superstructure (building 20) and the inclined sliding bearing, the seismic isolation effect is high without being affected by the type of seismic wave. It is possible to realize a seismic isolated building 1 that can be obtained. In particular, for long-period ground motion, both response acceleration and response displacement can be reduced compared to conventional natural rubber (laminated rubber) bearings, which is more effective than conventional seismic isolation.

As described above, the friction damper 5 and the seismic isolated building 1 according to the present embodiment do not require high manufacturing accuracy, are easy to manufacture and install, and shake with the frictional force that follows the displacement from small to medium-sized earthquakes to large earthquakes. It can be effectively reduced, and while suppressing the increase in acceleration of the seismic isolated building during a small and medium-sized earthquake, it is possible to suppress the excessive displacement by a certain resistance force during a large earthquake.

(Example)
Next, the results of analysis for verifying the effects of the friction damper 5 and the seismic isolated building 1 according to the present embodiment will be described in detail.
In the seismic response analysis of this example, the seismic isolated building of the above-described embodiment was simulated, and the analysis was performed using the analysis model of the one-mass point system shown in FIGS. 11 (a) and 11 (b). The condition of the structure in the analysis model was that the mass W was 4240 × 10 ³ kg.

In the analysis, the displacement-dependent friction damper 5 and the inclined sliding bearing 4 of the above-described embodiment are arranged between the building 20 and the foundation 21, and the friction damper 5 and the sliding rubber bearing are arranged between the building 20 and the foundation 21. Time history response analysis was performed using the following parameters in the comparative example case placed between and in the two analysis cases using.

The displacement-dependent friction damper 5 is the restoring force diagram shown in FIG. 12 in the above-described embodiment.
The frictional force when the axial displacement δ is 50 cm is expressed by F ₅₀ = R ₅₀ × W × g. g is the gravitational acceleration (9.8 m / sec ² ). Here, R ₅₀ = 3%, 4%, 5%, 6%, and 7%. The initial frictional force Fi is 25%, ₅₀ %, and 75% of F50.

The seismic waves shown in Table 1 and FIGS. 13 (a) to 13 (c) were used as analysis parameters for performing time history response analysis. As shown in Table 1, there are three patterns of seismic waves: Notification Kobe, Notification Kanto, and Notification Hachinohe. In Table 1, each notification wave has a long period, and shows the strong motion record, level, and maximum acceleration (cm / sec ² ), respectively. Level L2 indicates an extremely rare seismic motion. The seismic wave diagrams shown in FIGS. 13 (a) to 13 (c) show waveforms of time (sec) on the horizontal axis and acceleration (cm / sec ² ) on the vertical axis.

The embodiment case is a combination of a displacement dependent friction damper and an inclined sliding bearing. The tilt bearing at this time had a friction coefficient of 0.012 and a tilt angle of 1.5 °.
The comparative example case is a combination of a displacement-dependent friction damper and a natural rubber bearing. The natural rubber at this time had a horizontal rigidity k of 5.8 × 10 ³ kN / m and a damping constant h of 2%.

14 to 19 show the analysis results. As a result of these analyzes, the response values of the three seismic waves (Notification Kobe, Notification Kanto, Notification Hachinohe) are compared for each analysis case (Example case, Comparative example case). The response values shown in FIGS. 14 to 19 are graphs showing the relationship between the ratio of frictional force (damping force) F ₅₀ / weight Wg and acceleration (cm / sec ² ), the ratio and the seismic isolation response displacement (mm). It is a graph which shows the relationship, and the graph which shows the relationship between the said ratio and a residual displacement (mm). 14 (a) to 14 (c) are the analysis results of the example cases in the notification Kobe wave. 15 (a) to 15 (c) are the analysis results of the comparative example case in the notification Kobe wave. 16 (a) to 16 (c) are the analysis results of the example cases in the notification Kanto wave. 17 (a) to 17 (c) are the analysis results of the comparative example case in the notification Kanto wave. 18 (a) to 18 (c) are the analysis results of the Example case in the notification Hachinohe wave. 19 (a) to 19 (c) are the analysis results of the comparative example case in the notification Hachinohe wave.

From the above analysis results, the response acceleration increases as the ratio of the frictional force F ₅₀ / weight Wg increases. The response displacement decreases as the ratio of frictional force F ₅₀ / weight Wg increases.
It was also found that if the ratio of the frictional force F ₅₀ / weight Wg is the same for the response acceleration, the smaller the ratio of the initial frictional force Fi to F ₅₀ , the smaller the response acceleration.
For long-period ground motion (Notification Kobe, Notification Kanto, Notification Hachinohe), the example case (combination of displacement-dependent friction damper and tilt sliding bearing) is a comparative example case (combination of displacement-dependent friction damper and natural rubber bearing). It was confirmed that the response acceleration and response displacement were smaller than those of the above.

Further, when comparing the residual displacement, regardless of the type of seismic wave, the ratio of frictional force _F50 / weight Wg, and the ratio of initial frictional force, it is only 5 mm or less in the example case, and it is related to the seismic wave in the comparative example case. It will be several mm to 30 mm. As a result, it was found that the residual displacement can be kept smaller in the Example case than in the Comparative Example case.

From the analysis results of this example, it was confirmed that the displacement-dependent friction damper can obtain a high seismic isolation effect when combined with the inclined sliding bearing. In particular, it was found that the response acceleration and response displacement can be reduced compared to the conventional natural rubber bearings for long-period ground motion, which is more effective than the conventional seismic isolation.

Although the embodiment of the friction damper and the seismic isolated building according to the present invention has been described above, the present invention is not limited to the above embodiment and can be appropriately changed without departing from the spirit of the present invention.

For example, in the present embodiment, the friction damper 5 is configured by providing one intermediate steel plate 51 and a pair of outer steel plates 52, 52 so as to sandwich the intermediate steel plate 51, but these are the quantities. It is not limited to that. For example, it may be configured so as to be sandwiched between two intermediate steel plates 51 by three steel plates (corresponding to outer steel plates).

Further, in the present embodiment, the intermediate steel plate 51 is attached to the building 20 side and the outer steel plate 52 is attached to the foundation 21 side, but the intermediate steel plate 51 which is inverted in the axial direction X and has the sliding portion 51B is used as the foundation. It may be attached to 21 and the outer steel plate 52 may be provided on the building 20 side.
Further, the set values of the plurality of friction coefficients μ in the friction plate 53 are not limited to the above-described embodiment, and different quantities of friction coefficients μ can be appropriately set.

In addition, it is possible to replace the components in the above-described embodiment with well-known components as appropriate without departing from the spirit of the present invention.

1 Seismic isolation building 3 Seismic isolation system 4 Inclined sliding bearings 5 Friction damper 20 Building (superstructure)
21 Foundation (substructure)
51 Intermediate steel plate (first steel plate)
51A Steel plate part 51B Sliding part 52 Outer steel plate (second steel plate)
53 Friction plate (friction material)
52a Inner surface 54 High-strength bolt 55 Restraint steel plate

Claims (3)

An axial displacement-dependent friction damper connected to a substructure and a superstructure that is relatively mobile relative to the substructure and is arranged with the axial direction oriented horizontally.
The first steel plate attached to the superstructure and
A second steel plate attached to the lower structure and arranged so as to overlap the first steel plate in the plate thickness direction orthogonal to the axial direction, and
A friction material in which one of the first steel plate and the second steel plate is provided on a surface facing the other side and is set to a plurality of friction coefficients along the axial direction.
The other side is provided with a sliding portion provided on the other side and in contact with the friction material by generating a frictional force due to the relative displacement of the first steel plate and the second steel plate in the horizontal direction.
The frictional force generated between the friction material and the sliding portion when the first steel plate and the second steel plate are axially displaced in the axial direction is a first frictional force that increases substantially in proportion to the axial displacement. A friction damper that is set to obtain a second frictional force that becomes constant when a certain axial displacement is exceeded. The friction material is set so that the friction coefficient increases as the distance from the central portion in the axial direction increases on both sides in the axial direction.
The friction damper according to claim 1, wherein the sliding portion when the axial displacement on which no seismic force acts becomes 0 is arranged so as to be the central portion of the friction material. A seismic isolated building equipped with the friction damper according to claim 1 or 2.
The superstructure is attached to the friction damper and is relatively movable with respect to the substructure so that the amount of movement in the vertical direction increases in accordance with the increase in the amount of horizontal displacement of the superstructure. A seismic isolated building characterized by being equipped with a slanted sliding support to support.

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