JP3885549B2 - Pendulum type base isolation structure for structures - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pendulum type seismic isolation bearing structure for a structure applied to artificial ground, bridges, buildings, and other structures.
[0002]
[Prior art]
FIG. 3 shows an example of an artificial ground using buoyancy installed on a soft ground. The artificial ground 1 can be regarded as a bridge, and is composed of a platform 2 such as a steel pontoon type. For example, the artificial ground 1 includes four bridge piers 3, a footing pile foundation 4 and a seismic isolation device 5. This is a structure type in which most of the mounted load is canceled by using buoyancy, the horizontal load is reduced by the seismic isolation device 5, and the platform 2 is grounded and supported on the four piers 3 and the foundation 4. A building 6 is provided on the platform 2, and the platform 2 and the abutment 7 at both landfill sites are connected via a connecting bridge 8.
[0003]
For example, a structure as shown in FIG. 4 is considered as the seismic isolation device 5. FIG. 4 (a) is a seismic isolation rubber bearing structure under the surface of the water (pressure structure). A bottom of the platform 2 is formed with a supporting recess 50 under the surface where the upper part of the pier 3 is inserted, and on the upper surface of the pier 3. A seismic isolation rubber (laminated rubber) support 51 is installed via a liner 52, and air is supplied to the support recess 50 to ensure an airborne state. This structure has an advantage that the support portion does not protrude to the first floor level of the platform 2.
[0004]
FIG. 4 (b) shows a seismic isolation rubber bearing structure on the surface of the water. A gate-shaped bearing portion 53 into which the upper part of the pier 3 penetrating the platform 2 is inserted is projected on the upper surface of the platform 2, and the upper surface of the pier 3 is shown. In addition, a seismic isolation rubber (laminated rubber) support 51 is installed via a liner 52. Since this structure is usually under atmospheric pressure, the working environment is good, and since the work is performed on the upper part of the platform 2, workability is good.
[0005]
When the foundation ground sinks, in any case, the superstructure is provisionally received by the jack 54 and the liner 52 is adjusted.
[0006]
[Problems to be solved by the invention]
In the case of the conventional seismic isolation rubber bearing (laminated rubber) structure, since the compression spring coefficient is large, the vertical deformation is small, and the shear spring coefficient is small. Although there is an advantage that the effect can be increased, there are the following problems.
[0007]
(1) For the settlement of the foundation that occurs when the foundation ground is soft, the height is adjusted by inserting and removing the liner while the superstructure is temporarily received with a jack, so it is a laborious and time-consuming work. It becomes.
[0008]
(2) When the foundation ground is soft, uneven settlement often occurs between the foundations. When this uneven settlement occurs, tensile force may be generated on the support installed between the superstructure and the pier. Since ordinary seismic isolation rubber bearings have a low resistance to a tensile force, it is necessary to devise a method that does not generate a tensile force.
[0009]
(3) When the foundation ground is soft and lateral movement of the ground due to ground subsidence occurs, control is performed for the amount of shear deformation of the seismic isolation rubber bearing. Need to do.
[0010]
The present invention has been made in order to solve such problems. The purpose of the present invention is to obtain a desired seismic isolation effect with a relatively simple support structure and to subsidize the foundation when the foundation ground is soft. It is to provide a pendulum-type seismic isolation structure for a structure that can easily cope with non-uniform settlement, lateral movement of the ground, and the like.
[0011]
[Means for Solving the Problems]
Claim 1 of the present invention is a seismic isolation bearing structure provided between a structure and its support leg, and a lower part of the structure is provided with a penetrating portion through which the upper part of the support leg penetrates with a space around the support leg. The upper and lower ends of the suspension members arranged on both sides of the penetrating portion are respectively connected to the upper end of the support leg and the lower portion of the structure via a universal joint, and the structure is suspended and supported so as to be swingable in the horizontal direction. It is a pendulum-type seismic isolation structure of a structure characterized by The suspension member can be a suspension rod or suspension wire, and the upper and lower ends of the suspension member via a universal joint such as a pin or ball, respectively, and a supporting leg (such as a bridge pier) and a structure (artificial ground, bridge, building, etc.) ), And the structure is a pendulum structure that can swing horizontally with respect to the support leg.
[0012]
A second aspect of the present invention is the pendulum type seismic isolation structure for a structure according to the first aspect, wherein the length of the suspension member is adjustable. For example, by providing a male thread on the suspension rod and fixing the spherical member of the universal joint to the suspension rod with a nut, or by providing a turnbuckle in the middle of the suspension rod and rotating the nut or turnbuckle, Allow the length to be adjusted.
[0013]
According to a third aspect of the present invention, the structure is fixed to the support leg by a shaking prevention device that is released during an earthquake. Seismic support structure. During normal conditions and storms, the structure and bridge pier are fixed with a shake prevention device to prevent the structure from shaking due to wind and waves, etc. Separate from the support leg to allow pendulum movement.
[0014]
According to a fourth aspect of the present invention, the structure connected to the support leg is a floating structure utilizing buoyancy, and the pendulum type relief of the structure according to claim 1, 2, or 3 is provided. Seismic support structure. For example, when applying to artificial ground using buoyancy, the pier constructed on the footing pile foundation protrudes from the deck surface of the artificial ground to a sufficient height, and the artificial ground is supported by hanging from the upper part of the pier with a suspension member To do.
[0015]
In the configuration as described above, the structure and the support leg are fixed by the vibration preventing device during normal times or during storms, and the structure is prevented from being shaken by wind or the like. In the event of an earthquake, the anti-sway device is released, the structure is separated from the support legs, the structure becomes a pendulum structure, the natural period of the structure is prolonged, the seismic motion transmitted from the foundation ground is reduced, and seismic isolation An effect is obtained.
[0016]
When the foundation ground is soft and the foundation sinks in the future, the height of the structure can be easily adjusted only by adjusting the length of the suspension member. Also, even if the foundation ground is soft and uneven settlement occurs between the foundations in the future, the length of the suspension members on each foundation can be adjusted to level the structure, and each suspension member The load can be borne evenly. Furthermore, even if the foundation ground is soft and lateral movement occurs in the future due to ground subsidence, the universal joint of the suspension member can absorb the relative displacement of the support leg / foundation and structure, and the burden on the suspension member is also reduced. It can be eliminated and can easily cope with the lateral movement of the ground.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiment. This embodiment is an example of an artificial ground using buoyancy installed on soft ground. FIG. 1 is a partial side view of a structure showing an example of the pendulum type seismic isolation bearing structure of the present invention. FIG. 2 is a cross-sectional view showing an example of a suspension member having a pendulum type seismic isolation bearing structure.
[0018]
The artificial ground 1 is made up of a platform 2 such as a steel pontoon type as in the prior art, and has, for example, a total of four bridge piers 3 and footing pile foundations 4 arranged at two locations on both sides of the platform 2, respectively. 1 (see Fig. 3), as shown in Fig. 1, a pendulum-type seismic isolation structure 11 is provided on the pier 3 and most of the overload is offset by using the buoyancy of the platform 2 to The structure 11 reduces the horizontal load, and the platform 2 is suspended and supported on the four piers 3 and the foundation 4.
[0019]
The pendulum-type seismic isolation structure 11 mainly supports and supports the platform 2 so that it can swing in the horizontal direction by connecting the support beam 12 formed on the upper part of the pier 3 and the upper surface of the support beam 12 and the platform 2. The suspension rod 13, the platform 2, and the bridge pier 3 are fixed, and the wind sway prevention device 14 is released in the event of an earthquake.
[0020]
The platform 2 is provided with a penetrating portion (notch or through-hole whose outer surface opens) 15 of the pier 3 by boxing or the like so that the upper portion of the pier 3 protrudes from the upper surface of the platform 2 at a predetermined height. A support beam portion 12 protruding in the horizontal direction is integrally formed at the upper end portion of the pier 3.
[0021]
The suspension rods 13 are arranged in a pair in the X direction with the pier 3 interposed therebetween, or in pairs in the X direction and the Y direction, and the upper ends of the suspension rods 13 are connected to the support beam portion 12 by a universal joint (pin joint or ball). Connected via a universal joint (such as a joint) 16, and the lower end of the platform 2 is connected to the platform 2 via a universal joint (a universal joint such as a pin joint or a ball joint) 17, and the length can be adjusted by appropriate means. And
[0022]
For example, as shown in FIG. 2 (a), the upper universal joint 16 is composed of a spherical member 20 attached to the suspension rod 13 and a spherical receiving seat 21 provided on the upper surface of the support beam portion 12. The suspension rod 13 is inserted into the through-hole 12 a provided in 12, the spherical member 20 is penetrated by the male screw 13 a provided in the suspension rod 13, and the spherical member 20 is fixed by the nut 22. If the nut 22 is rotated, the length of the suspension rod 13 can be arbitrarily adjusted. The through hole 12a has a shape that expands downward so that the swinging of the suspension rod 13 is not hindered.
[0023]
Alternatively, as shown in FIG. 2 (b), a universal joint 16 made of pins or balls is fixed to the lower surface of the support beam portion 12, a turnbuckle 23 is provided in the middle portion of the suspension rod 13, and the suspension is suspended by operating the turnbuckle 23. The length of the rod 13 is arbitrarily adjusted. Also, FIG. 2 (a) and FIG. 2 (b) can be used in combination.
[0024]
The wind sway prevention device 14 is for fixing the platform 2 and the pier 3 so as to integrate the displacements in a normal state and a storm, and releasing the fixation so that the platform 2 can perform a pendulum movement in an earthquake. Yes, the sensor will detect earthquakes and remove the stopper. The wind sway prevention device 14 is installed between the rising member 30 and the upper portion of the pier 3 that integrally rise so as to surround the upper portion of the pier 3 from the upper surface of the platform 2.
[0025]
The artificial ground pendulum type seismic isolation structure 11 having the above-described structure operates as follows.
[0026]
(1) The platform 2 floating on the water surface is suspended and supported by the bridge pier 3 via a pendulum type seismic isolation structure 11. The load on the pier 3 and the foundation 4 is reduced by the buoyancy of the platform 2.
[0027]
(2) The platform 2 and the pier 3 are fixed by the wind sway prevention device 14 during normal times or during storms, and the platform 2 is prevented from shaking due to wind or waves.
[0028]
(3) In the event of an earthquake, fixing by the wind sway prevention device 14 is released, the platform 2 is disconnected from the pier 3, the superstructure such as the platform 2 becomes a pendulum structure, and the natural period of the superstructure becomes longer and is transmitted from the foundation ground. Seismic motion is reduced and seismic isolation effect is obtained. Since the natural period is determined by the length of the pendulum, the length of the suspension rod 13 is appropriately determined within the range of the long period.
[0029]
(4) When the foundation ground is soft and the foundation 4 sinks in the future, the height of the platform 2 can be easily adjusted by adjusting the length of the suspension rod 13.
[0030]
(5) Even if the foundation ground is soft and uneven settlement occurs between the foundations 4 and 4, the platform 2 can be leveled by adjusting the length of the suspension rod 13 of each foundation 4 respectively. At the same time, the load can be evenly applied to each suspension rod 13.
[0031]
(6) Even when the foundation ground is soft and lateral movement due to future land subsidence occurs, the universal joints 16 and 17 of the suspension rod 13 can absorb the relative displacement of the pier 3 and foundation 4 and the platform 2; The burden on the suspension rod 13 can be eliminated, and it is possible to easily cope with lateral movement.
[0032]
The suspension member and the length adjusting mechanism of the pendulum type seismic isolation structure 11 of the present invention are not limited to the illustrated example, and may be a winch, a wire rope, or the like. Moreover, the pendulum type seismic isolation structure of the present invention can be applied to seismic isolation of normal artificial ground, bridges, buildings, and other structures as well as artificial ground using buoyancy as described above. .
[0033]
【The invention's effect】
(1) Since the structure is suspended and supported on the support legs via the suspension members, the structure is made a pendulum structure, the natural period is lengthened, and the seismic motion transmitted from the foundation ground is reduced. A desired seismic isolation effect can be obtained with a relatively simple support structure. Since the structure and the support leg are fixed by the vibration preventing device during normal times and storms, the structure can be prevented from being shaken by wind or the like.
[0034]
(2) If the foundation ground is soft and the foundation sinks in the future, the height of the structure can be easily adjusted just by adjusting the length of the suspension member. Can respond.
[0035]
(3) Even if the foundation ground is soft and uneven settlement occurs between the foundations in the future, the length of the suspension members on each foundation can be adjusted to level the structure and each suspension member It is possible to load the load evenly and easily cope with the uneven settlement between the foundations.
[0036]
(4) Even if the foundation ground is soft and lateral movement due to future ground subsidence occurs, the universal joint of the suspension member can absorb the relative displacement of the support legs / foundation and structure, and the burden on the suspension member Can be eliminated, and it is possible to easily cope with the lateral movement of the ground.
[Brief description of the drawings]
FIG. 1 is a partial side view of a structure showing an example of a pendulum-type seismic isolation bearing structure of the present invention.
FIG. 2 is a cross-sectional view showing a specific example of a suspension rod having a pendulum-type seismic isolation bearing structure according to the present invention.
FIG. 3 is a side view showing an example of artificial ground using buoyancy to which the present invention is applied.
4 is a partial side view showing a conventional seismic isolation bearing structure in the artificial ground of FIG. 3. FIG.
[Explanation of symbols]
1 ... Artificial ground 2 ... Platform 3 ... Pier 4 ... Footing pile foundation 5 ... Seismic isolation device 6 ... Building 7 ... Abutment 8 ... Connecting bridge 11 ... Pendulum type base isolation structure 12 ... Support beam portion 12a ... through hole 13 ... suspending rod 13a ... male screw 14 ... wind vibration prevention device 15 ... through portion 16 ... universal joint 17 ... universal joint 20 ... spherical member 21 ... spherical receiving seat 22 ... ... Nut 23 ... Turnbuckle 30 ... Rising member

Claims (4)

It is a seismic isolation structure provided between a structure and its support legs. A penetration part is provided in the lower part of the structure, with the upper part of the support leg penetrating with a space around the support leg. The upper and lower ends of the suspended members are connected to the upper ends of the support legs and the lower part of the structure through universal joints, and the structure is suspended and supported so as to be swingable in the horizontal direction. A pendulum-type seismic isolation structure for objects.   2. The pendulum-type seismic isolation bearing structure according to claim 1, wherein the length of the suspension member is adjustable.   The pendulum-type seismic isolation structure for a structure according to claim 1 or 2, wherein the structure is fixed to the support leg by a shake prevention device that is released during an earthquake.   4. A pendulum type seismic isolation structure for a structure according to claim 1, wherein the structure connected to the support leg is a floating structure utilizing buoyancy.

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