Cushioning device for protecting objects from seismic effects

 

(57) Abstract:

The invention relates to a seismic-resistant construction. Its use helps to ensure effective protection of the object in the horizontal direction by reducing any value or complete shutdown of the dry friction force between the Foundation and base plate due to the fact that their adjacent surfaces are in the form in which some parts of the contact plate, and the other made with a backlash in the form of cavities filled with fluid, for example water under excessive hydrostatic pressure, which is kept connecting plate compensator, allowing their relative horizontal movement. In vertical direction the asset protection provided by increasing the period of natural oscillations on the plates of the support structure depreciable object, made in the form of partially floating in the liquid and partially resting on a layer of compressed air caisson, consisting of at least two concentric spaced glasses, in which the annular gap between the outer and its nearest domestic cups covered bottom waterproof bottom, connected at its outer is ivyshim in decompression cavity pressure of compressed air, and fluid-filled cavity between the plates and the lower part of the caisson cavity are connected by pipelines with the reserve tanks located above the respective cavities. 9 C. p. F.-ly, 2 Il.

The invention relates to earthquake-resistant construction, namely the construction of buildings and structures, which provides a device or system of seismic isolation. It can be used for protection from earthquakes particularly important and unique structures, in particular units of ground and underground nuclear power plants, high-rise buildings, radio stations, observatories, stores of ammunition and special equipment with low seismogeological.

Known shock-absorbing device for protecting objects from seismic effects, including lower and upper bearing zone with the adjacent surfaces of the polygonal shape, having the form of protrusions and recesses. Some of them has an angled slip pad with anti-friction pads to restore the original position due to gravitational forces, the part has a horizontal platform and a vertical wall for supporting columns of the building frame (SU, N 1206398,CL E 02 D 27/34, 1986).

Uh what dostoinstva is the use of inclined platforms slip to prevent residual displacements. However, the proposed scheme slip on mutually parallel faces justified only when plane-parallel movement of the support belts and impossible when their azimuthal spreads. The latter can occur when exposed to a shear wave at an oblique approach of waves to extensive buildings and structures that do not possess axial symmetry of the mass distribution.

Closest to the described invention is a cushioning device for protecting objects from seismic effects, including the base plate, on which is located the base plate with the support structure depreciable object, and the Foundation and base plate are located relative to each other with a horizontal gap and is connected to the outer side of the toroidal wall with formation of a chamber of the hardened flexible material filled with a special liquid. Depreciation is due to compression or expansion (deformation) of a toroidal section of the camera in action at her across the plates of the external load (PCT 88/04710, CL E 02 D 27/34, 1988).

When implementing the known device is not ensured stability of the vertical position of amortis the second gas chamber of the shock absorber cannot occur restoring force, preventing the rotation (tilt) of the upper support plate with an asymmetric distribution of mass of the object and a horizontal impact. In addition, almost unreal is a solid toroidal shell with a diameter of 50 m in factory conditions, as well as to ensure the required tightness during installation of separate sections at the construction site of the object, and execute it with the necessary flexibility, strength, gas impermeability and durability.

To eliminate the above disadvantages of the known device requires to solve the following problems:

to minimize the critical shock-absorbing device for amplitude-frequency spectrum of the seismic action, i.e. the dependence of its dynamic efficiency from nature (shape changes over time) and intensity of the vibrations by using the power relations between depreciable object and the base, allowing to realize provocative characteristics, neutral to the type of seismic effects; this can be achieved using the device, which reduces to the desired values or completely excluded from the process of interaction of the object with the base force of dry friction, awsume the IMO also increase the period of vertical oscillations of the object to the values several times greater than the period of the main destructive phase of the earthquake;

to increase the value of the free motion of the device in horizontal and vertical directions to values higher than the moving base;

to provide the desired damping and a guaranteed return of depreciable object in the original design position after impact;

to exclude the possibility of disengagement of the base plates from the base;

to increase the capacity of the device and the resistance of the object, and also to reduce the dangerous consequences of emergency situations on the basis of applications distributed over the area of power relations;

to improve technical and economic performance of the device and installation, allowing the system to implement the seismic protection directly at the construction site means available;

to simplify the conditions of daily operation, limiting their usual requirements of construction norms and rules, while maintaining high reliability and efficiency of the system of seismic protection for a long period;

to ensure ease of installation, inspection, preventive maintenance and repairs.

To achieve obespechivaushyi, contains the base plate where the base plate with the support structure depreciable object adjacent the surface of the plates have the form, in which some parts of the contact plate, and the other made with a backlash in the form of planes filled with liquid, for example water under excessive hydrostatic pressure, which is kept connecting plate expansion joint allowing relative horizontal movement, and on the bearing plate design shock absorbing object made in the form of partially floating in the liquid and partially resting on a layer of compressed air caisson, consisting of at least two concentric spaced cups, moreover, the annular gap between the outer and its nearest domestic cups covered bottom waterproof bottom, connected at its outer perimeter with base plate compensator, allowing their relative vertical movement and uderjivauschiy in decompression cavity pressure compressed air and fluid-filled cavity between the plates and the lower part of the caisson cavity are connected by pipelines with the reserve tanks located you the working of protrusions and recesses of the same height, the horizontal gap between the walls of which exceeds the maximum expected relative movements of the plates. In addition to the main pipeline connecting the cavity between the plates with the reserve capacity may be connected to additional tubing reservoir above the reserve tanks; primary and secondary pipelines it is reasonable to provide valves that allow fluid only in the direction of the cavities. The glasses of the caisson can be divided by partitions into compartments, which are filled with compressed air and connected holes in the walls of the cups above the fluid level in the caisson; the inner cups of the caisson can be blocked by a perforated diaphragm located below the liquid level in the caisson; the base plate may be a glass, telescopically entering the Central glass caisson; plate may have a circular or oval shape, and the joints can be made in the form of a flexible toroidal shell, forming a semicircle, and the guide line, the horizontal projection of the external circuit connected elements, which is fixed to the shell, moreover, in this case, the shell of the compensator may be the covered on their outer perimeter; the shell of the compensator can be made from blanks of sheet material, having the shape of an isosceles trapezoid.

The presence between the plates of cavities filled with fluid under pressure, reduces friction between the plates. The base plate has a partially suspended, "floating" on the fluid layer in the gap. On moistened friction surfaces is reduced and simultaneously the friction coefficient. When executing the adjacent surfaces of the plates in the form of alternating protrusions and recesses at the same time provides additional damping of the horizontal oscillations due to viscous friction of the fluid as it moves in the gaps between the projections and recesses of the plates.

The connection to the main pipeline cavities between the plates with the reserve tanks creates cavities excessive hydrostatic pressure. When the total value of the vertical component of hydrostatic pressure greater than the weight of the support plate with the object, the force of friction will stop at zero. In this case, when the relative horizontal movement of plates on the object affected by the forces of hydrodynamic pressure and viscous friction of the fluid and the elastic response is Ino of plate motion (which does not exceed 0.5 m/sec) and high flexibility of the thin shell. Their value can be adjusted within wide limits by means of constructive activities, changes, for example, shape, height, arrangement of protrusions and recesses, the gap between them and the flexibility of the compensator, thereby achieving the optimum performance of the device. The connection of the main pipeline an additional pipeline from the reservoir allows you to completely disable the force of friction from the process of interaction of the plates. When this tank is located above the reserve capacity on the altitude at which excess fluid pressure in the cavities balances the weight of the support plate with embedded structures, thereby reducing to zero the normal force and hence the friction force at the contact sites of the projections and recesses of the plates. Valves and valves enable the system to work. At the moment of impact, or before him, or manually, by a sensor, connected to the cavity between the plates of the tank and disconnected from her back capacity on the period of exposure. Existing methods and apparatus allow you to register earlier phenomena preceding the main destructive phase of the earthquake, which include: parish primary (longitudinal) waves of low intensity (parshakov) granted the power of nsimemory fluid pressure is transmitted almost instantly, and the response time of the valve is small compared to the interval between the precursor of the earthquake and its destructive phase, it is possible to ensure timely inclusion in the work of the Executive mechanisms of seismic protection. This scheme allows, depending on the specific conditions and needs to implement multiple modes of seismic protection.

The return of the object in the original design position after seismic excitation is provided facing toward the center of the fundamental slab the elastic forces of the expansion joint and unbalanced hydrostatic pressure resulting from its non-symmetry of the distribution on the inner surface of the shell of the compensator when smeshannom the location of the plates. Such a return is guaranteed because the friction force can be reduced to any value using hydrostatic pressure and force the viscous resistance at low speed bias is negligible.

The number of glasses of the support structure depends on the designs and dimensions of the caisson, in particular the diameter and span of supporting elements overlap decompression cavity.

Division of glasses caisson on interconnected compartment is thereby lowering the natural frequency of vertical oscillation of depreciable object on the pneumatic spring to the desired values, which depends only on this volume and, secondly, to increase the stability of the caisson at asymmetric mass distribution and the influence of wind loads, because of the overlapping bottom waterproof bottom ring cavity plays the role of floating in the liquid ship pontoon, allowing a wide range to change the position of metacentre, depends on the stability of the pontoon.

The presence in the cavity of the inner cups of the caisson perforated diaphragm located below the level they are on fluid provides the required damping vertical oscillations of the caisson by throttling fluid through the openings in the diaphragm, and the implementation of the support plate in some cases with glass, telescopically within the Central Cup of the caisson, it is necessary to exclude the possibility of the appearance of the rolls of the caisson and to ensure strict stability of its vertical position.

Running boards and caisson round or oval in plan, and expansion joints in the form of a flexible membrane avoids abrupt changes in the shape of the compensator and thereby ensure the desired flexibility of the shell, to reduce turbulence hydraulic flow is convex upward in the annular gap between the vertical cantilever walls, framing anchor plates on their outer perimeter. This allows you to share the load from radial hydrostatic pressure and thereby reduce tensile stresses in the shell. If necessary, it can be supported with the outer side of the radial lengths of rope or curved rods having a cross-sectional shape of the shell and secured by their ends to the circuit connected support elements. In cases when the shell expansion joint capable of withstanding radial hydrostatic pressure without passing effort at framing the wall (at low hydrostatic pressure or a small diameter expansion joints), it can be a bulge in the radial direction, and the need for cantilever walls disappears.

When executing shell compensator from blanks of sheet material as the latter can be used, for example a thin sheet stainless steel, rubber or synthetic fabric, and others, including composite materials having the necessary strength and flexibility. Trapezoidal shape of the workpiece material greatly simplifies the manufacturing technology of the shell and pozvolyaet radial seams, reinforced metal banding. In the manufacture of expansion joints of large diameter, which can reach tens of meters, such technology is the installation does not require the involvement of specialized industry and is almost the only option. The joints of small diameter can be produced according to the technology companies of rubber, in particular a width of industries.

Connecting a fluid-filled cavities to the reserve tank and through them to the water supply network allows not only to constantly maintain the desired hydrostatic pressure of the liquid, but also in a timely manner to compensate for the leak in the case of poor workmanship or damage to the shell. This increases the reliability of the device without being particularly stringent requirements for sealing joints and waterproofing of cavities filled with fluid. Fall with dangerous consequences of unforeseen damage to the joints, which in contrast to the high-pressure cylinders can be in the worst case, only local damage in the form of punctures shell or breach seals in place of its contiguity to the plates. Since the compartments of the casing and the surrounding area will occur with the same gradient. Moreover, it will be smooth and slow due to the fact that the shell expansion joints separated from the cavities filled with compressed air, a fluid layer, which due to its higher viscosity has a low fluidity. This factor also reduces and its diffusion through the reflecting structure. In this regard, the violation of the geometry in the caisson can only lead to a gradual lowering of the object on the support plate, and in the cavities between the plates to increase the friction force is determined by the friction coefficient wetted surfaces of the plates.

In Fig. 1 shows in section the construction of the cushioning device to protect nuclear power plant unit; Fig. 2, this plan And As shown in Fig. 1.

The device consists of located on soil Foundation base plate 1 on which the base plate 2 placed on it support structure depreciable 3 object 4. Adjacent surfaces of the plates are in the form of alternating protrusions and recesses, gaps 5 between the walls are of the same height exceeds the maximum horizontal displacement calculated seismic effects. The protrusions and recesses in contact with their horizontal square excessive hydrostatic pressure, held a connecting plate compensator 7, located around their perimeter and allowing relative horizontal movement of the plates. If you need to increase the force of viscous friction instead of water may be used a liquid having a higher viscous properties.

To create in the cavity 5 of the excess hydrostatic pressure provided connected with her main pipe 8 and is constantly filled with liquid reserve tank 9, which is connected to the water mains to maintain the capacity required level of liquid in case of leakage, damage compensator 7. The main pipe 8 may be connected to additional tubing 10 with the tank 11 above reserve capacity.

For extra pipeline 10 includes a valve 12 and the main pipeline 8 valve 13, which allow simultaneous opening and closing of the second to increase the pressure in the cavity 5 to the value at which the friction force on the contact areas 6 of the base plate 1 and the support 2 will be equal to zero.

On the plate 2 supporting structure 3 made in the form of partially floating in the liquid, partially hopefullie vertical movement and keeps the pressure in the decompression cavity. The caisson consists of concentric spaced cups 15, 16 and 17 separated by partitions into compartments 18. The annular gap between the outer 15 and its nearest inner Cup 16 is overlapped with the bottom plate 19, precluding the flow of fluid into the cavity between them, and filled with compressed air compartments communicate through radial holes 20 located in the walls of the cups at levels above the maximum liquid level in the caisson. The cavity between the inner cups covered the bottom of the perforated aperture 21, thereby providing the throttling of fluid through its holes damping vertical oscillations. The base plate 2 may be provided, if necessary, the glass 22, telescopically within the Central cavity of the Cup 17 caisson. The joints 7 and 14 are convex upward in the annular gap between the outer glass 15 and the vertical cantilever walls 23 and 24, the frame plates 1 and 2 at their outer perimeter.

The device operates as follows.

When horizontal vibrations of a base plate 1, caused by seismic impact, based on her base plate 2 moves as a result of its slippage relative to setelem the movement of plates, the more intense the reduction of these parameters.

There are two basic modes of operation cushioning device. First it is advisable to use to protect objects that have valid under the terms of their seismogeological friction force exceeds the force of wind influence, is able to move the object from the initial design position. In this case, the reserve tank 9 is located at a height at which the hydrostatic pressure of the fluid in the cavity between the plates 5 provides a reduction of the friction force to a value smaller than the maximum allowable for object inertial load, and greater than the force of wind influence. Hydrostatic pressure in the cavity remains the same as during the daily operation of the facility, and in the process of seismic effects. This mode can also be used for amortization of objects that are not exposed to wind loads, for example for equipment located in confined spaces. The second mode is used to protect objects with low seismogeological and exposed at the same time, the influence of intensive wind loads. In this scenario, the backup capacity of 9 RA which has been created reducing friction during seismic excitation is provided by the simultaneous operation with a valve 12 of the tank 11, located above the reserve tank 9, and disconnecting the latter from the cavity 5 through the valve 13 of the main pipe 9. As a result, the cavity 5 is created hydrostatic pressure, which balances the weight of the support plate 2 located here design 3 and depreciable object 4, thereby reducing to zero the force of friction or turn it off from the process of interaction between plates 1 and 2.

The reduction of the vertical components of the seismic action is provided by a low frequency (longer period) of oscillations of the depreciable object resting on a layer of compressed air, performed in this case the role of the pneumatic springs low rigidity. Vertical oscillations of a base plate 1 and located it on the support plate 2 is (more static) compression or rarefaction of the air in the cavities of the casing 3. At small relative changes of air volume stiffness of the air spring will be small, which allows us to provide the required reduction efficiency of seismic impact. The relative volume change depends on the initial value and the increment in the process fluctuations. The necessary balance between the decomposition great difficulties and is carried out by selection of the appropriate altitude decompression cavity.

The assessment of social significance and feasibility of the effectiveness of the device should, apparently, to produce considering the fact that

annually in the world, there are dozens of intense earthquake, which killed thousands of people and applied economic damages calculated in many billions of dollars (for example, in 1976, only three earthquakes killed about 700,000 people);

currently, there are no ways to predict earthquakes and to make a precise estimation of their parameters necessary for the application of deterministic methods of calculation of constructions, remedies and expected impacts of seismic effects, probabilistic methods has not yet received much attention because of the devastating earthquake belong to the category of unique events that have not yet gained the necessary static material;

guaranteed effective protection from earthquakes, especially with low seismogeological, is possible only on the basis of shock-absorbing devices, neutral to the amplitude-frequency spectrum of influences, which when earthquakes are random in nature, katyayini qualities to ensure protection during the experimental values and the most unfavorable combinations of parameters of seismic effects, which occur when a catastrophic, destructive earthquakes.

Such devices may include and claimed, because the transfer of the protected object, the horizontal component of the seismic action through regulatory force of dry friction and the vertical through the elastic reaction of the compressed air, allowing the low frequency of natural oscillations of depreciable object.

The force of dry friction, which in this case is the main cause of transmission of the horizontal component of the impact depends on the friction coefficient and the normal pressure between the friction surfaces. It does not depend on the amplitude-frequency characteristics of the impact. The device allows to reduce this effect to any value or to completely eliminate it from the process of interaction of the base with the object during the earthquake, thereby ensuring its effective protection. The device also allows you to increase the period of vertical oscillations of the object to values several times accepts the m for oscillation, possessing higher compared with frequencies, it does not transmit them to the protected object.

The possibility of practical realization of the claimed device, having the qualities mentioned above, is confirmed by the results of elementary estimates, which are made for the most unfavorable (limiting) conditions. As an example, below is data related to depreciable device used to protect against the most intense earthquake nuclear power plant unit, which is a cylindrical structure with a diameter of 50 m, a height of 60 m and a weight of 70000 so In this case, the maximum hydrostatic pressure in the cavities between the plates and in the caisson is about 35 t/m2and the force per linear inch of cross-section of the shell expansion joints, retaining its pressure and located the bulge upward in the annular gap width of 0.5 between cantilever walls, framing plate, not more than 100 kg/see this effort stretching stresses in the material of the shell thickness, for example 2 mm, is about 500 kg/cm2that is several times lower valid for steels and quite applicable to the seismic effects, contains the base plate where the base plate with the support structure depreciable object, characterized in that the adjacent surfaces of the plates are in the form in which some parts of the contact plate, and the other made with a backlash in the form of cavities filled with fluid, for example water under excessive hydrostatic pressure, which is kept connecting plate compensator, allowing their relative horizontal movement, and on the bearing plate design depreciable object made in the form of partially floating in the liquid and partially resting on a layer of compressed air caisson, consisting of at least two concentrically arranged the glasses, and the annular gap between the outer and its nearest domestic cups covered bottom waterproof bottom, connected at its outer perimeter with base plate compensator, allowing their relative vertical movement and restraint in decompression cavity pressure compressed air and fluid-filled cavity between the plates and the lower part of the caisson cavity are connected by pipelines from the backup capacity is s the surface of the plates are in the form of alternating protrusions and recesses of the same height, the horizontal gap between the walls of which exceeds the maximum expected relative movements of the plates.

3. The device under item 1, characterized in that the main pipeline connecting the cavity between the plates with the reserve capacity of the connected additional pipeline reservoir above reserve capacity.

4. The device according to p. 3, characterized in that the main and auxiliary piping fitted with valves that allow fluid only in the direction of the cavities.

5. The device under item 1, characterized in that the glasses of the casing divided by partitions into compartments, which are filled with compressed air and connected through holes in the walls of the cups above the fluid level in the caisson.

6. The device under item 1, characterized in that the inner cups of the caisson overlapped perforated diaphragm located below the liquid level in the caisson.

7. The device under item 1, characterized in that the base plate is a glass, telescopically entering the Central glass caisson.

8. The device according to p. 1, wherein the base and support plate, and located on the last caisson kazuomi forming a semicircle and the guide lines of horizontal projection of the external circuit connected to each other by joints, respectively, the base and bearing plates, as well as the support plate and caisson.

9. The device under item 8, characterized in that the shell expansion joints are convex upward in the gaps between the vertical cantilever walls, framing on the outer perimeter, respectively, the base and the support plate and the support plate and the caisson.

10. The device according to PP. 1 and 8, characterized in that the shell of the compensator is made from blanks of sheet material, having the shape of an isosceles trapezoid.

 

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9 cl, 5 dwg

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