EP0056258A2 - Device for damping oscillations and energy absorption - Google Patents

Abstract

The patent is a vibration damping insert designed to reduce seismic forces and stresses on buildings. It is installed between the foundation and the wall construction to prevent the forwarding of floor movements. It is characteristic of them that the insert construction is formed by an elastic-plastic spring system to increase the durability. The spring system contains a part for movement damping with great ability to change shape and a part for energy absorption with great effectiveness. The part for movement damping consists of a layered structure, which is composed of rubber plates placed on top of one another and steel plates surrounding them. The energy absorption part consists of a series of steel mandrels that extend into the opposing surfaces of the foundation and the wall construction and can absorb stresses greater than those resulting from the maximum wind load.

Description

The patent is a vibration damping insert designed to reduce seismic forces and stresses that occur in buildings. The insert construction serves to eliminate, or at least to reduce, the transmission of ground movements, and it is installed between the foundation and the wall construction.

Buildings have to endure seismic forces in such cases if they perform accelerated movements contrary to the original idle state due to earthquakes. According to Newton and D'Alembert's theorem, the magnitude of the seismic forces is directly proportional to the mass of the structure and the acceleration that occurs. From the point of view of the reduction in seismic forces, any effort that is aimed at reducing the mass of structures is important.

With the development of architecture, the mass of buildings has also decreased significantly to date, and this process is likely to continue in the future. In this way you can only reduce the weight of buildings, because the payload is related to the function of the building, so their reduction can only be achieved in certain cases,

There is another possible method for at least partially eliminating accelerated movements due to earthquakes, whereby the foundation and wall construction of the building an intermediate construction is installed which is suitable for consuming energy. Such a solution has been worked out in Yugoslavia, for example.

According to the proposal, about 1 m high walls are installed between the foundation and the wall structure, which burst during earthquakes. Due to the changes in shape, some of the energy is really used up. After the earthquake, the damaged walls can be replaced in sections. The ability of the wall to consume energy is achieved by using such mortar which is capable of withstanding large changes in shape when the wall is walled.

In order to achieve a similar goal and to absorb energy, a solution has been developed in the USA in which inserts for absorbing energy are installed between the foundation and the wall construction and between the foundation and the floor. In the first place, the inserts are rolls with limited movement, in the latter place they are plastic sliding plates.

In the United States, such a type of energy absorption has been proposed, in which steel plates would be placed between the floor and the structure, which can also withstand torsion and longitudinal shape change. The idea that rubber springs were installed between the foundation and the wall structure was also published in the USA. The installation of the rubber blocks between the foundation and the wall construction has also been implemented in practice in Yugoslavia. Such a school was built in Skopje after the 1963 earthquake - based on plans from Switzerland - and it actually stands on rubber blocks.

Both in Japan and in the Soviet Union, such methods have been developed for damping vibrations, in which the absorption of energy takes place with the help of the continuous modification of reinforced concrete columns. According to the Japanese proposal, there are approximately 1.5 m high reinforced concrete columns between the foundation and the wall structure to accommodate. They will be designed in such a way that their energy of plastic shape change is in balance with the kinetic energy that occurs during earthquakes.

Similarly, according to the Soviet proposal, the building was erected on one floor with high columns; its elastic-plastic change in shape causes a reduction in the kinetic energy conducted upwards. Such a solution has also been worked out in the Soviet Union, in which so-called "triggerable" connections are also installed on the ground floor. Their peculiarity is that they perish when forces exceed a certain limit. It is prevented that accelerations in the horizontal direction occur to an excessive extent and are passed on to the wall construction. Lattice brackets and partly vertical columns are proposed for this purpose.

Swiss Patent No. 584,333 contains a peculiar solution for reducing the effects of seismic forces. This is the support of spherical tanks for the storage of liquid. The tanks are placed on articulated supports that emanate from their plane of symmetry. The bottom tangent of the tank is approximately one meter above the ground. A rigid ring is welded to the tank from below, which is connected to the foundation by three horizontal steel bars that enclose 120 ° with each other. The ends of the bars are connected to the ring as well as to the foundation by ball joints. Pistons for vibration damping are located approximately in the middle of the rods. The proposal in the Swiss description contains good ideas, but in reality it can only be used in very limited areas, it cannot be used in buildings. The complexity and cost of the structure are also disadvantageous, and their maintenance requires a significant amount of living work.

The solution, which contains patent No. 3,940,895 in the USA, was developed according to other principles, but with the use of known sets of technical vibration theory. The essential thing is that to a vibrating mass - e.g. to the building or part of it - with the help of a rigid rod and a support, a smaller mass is connected so that when the larger mass is accelerated, the smaller mass is accelerated in the opposite direction. The degree of damping can be set with the aid of the geometric relationships of the rigid connection between the two masses. The physical background of the solution is real and obvious, on the one hand the real solution is costly, on the other hand the damping is only effective in one level, in the level of the support, to expand in other directions is complicated and difficult, e.g. through the use of ball joints and multi-directional support.

The most convenient of the known solutions appears to be that found in U.S. Patent Specification No. 4,121,393. In this, elastic elements are installed between the foundation and the wall construction, which reduces the transmission of earth movements. Some parts of the elements consist of bronze, copper, titanium and other plates, between which friction occurs due to the vertical load. The frictional force serves to dampen the vibration, despite the originality it is not to be expected that the solution will widen widely, since the friction cannot be regarded as constant with repeated quakes. In addition, the degree of damping cannot be followed mathematically, on the one hand because of the change in shape of the individual elements, and on the other hand because of the change in the properties of the roughness on the surfaces that touch.

None of the methods set out in the above is able to solve the problem satisfactorily. your The most important deficiency is that the structural elements, if damaged, are unable to carry the vertical load with certainty. Because of the large changes in shape, mainly because of the horizontal direction, serious stability problems arise. Therefore, even if the upper parts of the structure are not damaged due to the seismic stress, the buildings often collapse due to the inadequacies of the stability of the pillars.

The fact that the direction of the earthquakes and the resulting seismic forces are completely arbitrary is a major concern - and it has not yet been resolved - with the known constructions. The design solutions do not allow adaptation to arbitrariness, which means that the rigidity in the horizontal plane is almost the same in every direction. Attempts have been made to help with springs made from rubber blocks, but the method has not been shown to absorb enough energy due to the merely elastic shape change.

In the known solutions, the difficulties that have arisen are of an economic nature. The cost of the load bearing. Constructions in average buildings account for around 40% of the full investment costs, while the remaining 60% is used for other constructions such as doors, windows, room partition walls, coverings, installation equipment and other systems that are related to the building in general stand. A significant proportion of them become unusable in quakes of greater intensity even if the load-bearing structures do not break. However, the greater concern is caused by the repair and reinforcement of load-bearing structures, but in most cases it is impossible to ensure that the damaged load-bearing structure has the original load-bearing properties when the earthquakes are repeated.

The basis of the patent is the knowledge that such a liner construction should be used while maintaining the advantages of the most advanced, but the shortcomings must be remedied. It should then be installed between the foundation and the wall structure. The foundation "lives" together with the ground as a result of the seismic forces, so the same movement characteristics - speed, acceleration, amplitude - are valid as for the ground itself, while only those movements occur in the wall construction, the formation of which is intermediate Allow elastic-plastic insert constructions.

In other words, by choosing the insert construction for damping, we can control the maximum horizontal load that the wall construction should receive. This can be achieved by installing such a spring system between the foundation and the wall construction, which allows at most those seismic forces that would arise horizontally from the wind load, while the system "flows" when higher forces occur, and therefore because of its plastic Shape change is automatically unsuitable for the transmission of larger forces.

It is also part of the patent concept that the insert construction for the damping is to be put together from a damping part with a great ability to change the elastic shape, and from an energy absorption part (plastic part) with great effectiveness. The part for the movement damping can be constructed easily and well as a construction consisting of alternating rubber layers and steel plates. The energy absorption part can consist of such, expediently vertical steel mandrels or of a set of steel mandrels which extend both into the foundation and into the wall construction. The dimensions of the mandrels are chosen so that they come into the flow area at horizontal loads greater than the wind load.

According to the goal set, the insert construction for damping according to the patent serves to reduce seismic forces and stresses on buildings - which prevents or at least reduces the movement of ground movements and is installed between the foundation and the wall construction - in such a way that the insert construction increases the rigidity of one elastic-plastic spring system is formed, the spring system contains a part of the movement damping with high ability of elastic shape change, as well as an energy absorption part (plastic part) with great effectiveness, the part for movement damping consists of superimposed rubber layers, which are surrounded by steel plates , the part for energy absorption consists of rows of steel mandrels that extend into the opposing planes of the foundation and the wall construction, and with greater loads than the one that results from the maximum wind load res are ultimately unsuitable for absorbing the stress.

Another characteristic of the insert construction for damping according to the patent can be that the part for movement damping is composed of at least two layers of hard rubber plates and at least three layers of steel plates, the layer construction developed in this way advantageously has both on the side of the base body and on the side of the wall construction one base for the load distribution. Both the base body and the wall construction are suitable for holding the steel mandrels for energy absorption, and they usually have sleeves made of steel pipes. The sleeves are embedded in the base body as well as in the wall construction without any possibility of movement, advantageous, they are concreted in.

The buohsen reach into the interior of the base body and the wall construction at a depth that is at least four times, but advantageously at least six times the diameter of the make up their diameter. The steel mandrels extend into the interior of the bushes at a depth that is at least three times, but advantageously at least five times their diameter. An air cushion is left between the ends of the steel mandrels and the lower part of the bushings.

The steel mandrels are advantageously loosely traversed by the layered structures, which are composed of rubber plates and steel plates, when an air cushion is released. Between the outer lateral surface of the steel mandrels and the inner lateral surface of the bushes, a lubricant is expediently applied in film-like thin layers to reduce the friction. Both the base body and the wall construction near the bushes expediently have reinforcement cells in the form of spatial brackets.

In the expedient embodiment of the insert construction for damping, the elastic-plastic spring system is installed in sections between the base body and the wall construction, and each section contains both a part for movement damping and a part for energy absorption.

The entire spring system, or possibly some of its parts, have bushes with less stiffness along the edges instead of the steel mandrels. The additional bushings are embedded in an elastic filler.

The greatest advantage of the insert construction for damping according to the patent is that in the event of an earthquake, the energy absorption part comes into the flow area as a result of forces which exceed the stress from the wind load, so that it can come from the foundation which is together with the ground moved, no further, larger forces on the wall construction, forward.

The stratified motion damping part is able to ask vertical forces, further that it is due to repeated quakes in a vertical plane behaves as an elastic support, the horizontal movements are dampened by it. The energy absorption part of the insert construction, which contains the vertical steel mandrels, can - due to its character - only absorb forces in the horizontal direction, at the expense of the plastic shape change of the mandrels it can absorb the energies that were generated during the quake.

The insert construction works according to the calculations based on the so-called "progressive suspension". It can therefore be determined with great accuracy that new spring elements only come into play to a certain extent after the change in shape has occurred, which can only undergo elastic changes in shape. As a result, those elastic reaction forces arise in the parts that have only undergone elastic shape changes, which prevent the wall structure of the building from being displaced horizontally beyond a certain limit.

It is also favorable that, due to the geometrical and structural design of the energy absorption part, it works in the same way in the horizontal plane in every direction. In this way, no matter in which direction the quake occurs, the building always behaves in the same way. Thanks to the insert construction according to the patent, the investment costs of the construction are also lower, since the load-bearing construction can only be dimensioned for the quake with the prescribed intensity for the wind load, the foundation and the basement. Due to the exclusion of the transmission of a force greater than the wind load, in the event of an earthquake, neither the load-bearing structure, nor the other furnishings and additional structures of the structure are damaged.

• Bild 1 schematische Anordnung der Einlagekonstruktion in nenkrechtem Schnitt,
• Bild 2 die Anordnung laut Bild 1 in Daraufsicht,
• Bild 3 der Stahldorn und seine Umgebung in vergrößertem Maßstab im Vergleich zu Bild 1
• Bild 4 Ausbildung kleinerer Steifdornen an den Rändern der Einlagekonstruktion.

The patent is explained in more detail in the context of an example with reference to drawings. The attached attachments are on

• Figure 1 schematic arrangement of the insert construction in a vertical section,
• Figure 2 shows the arrangement according to Figure 1,
• Fig. 3 the steel mandrel and its surroundings on an enlarged scale compared to Fig. 1
• Fig. 4 Formation of smaller stiff mandrels at the edges of the insert construction.

Figure 1 shows a section of the floor plan A, above the wall construction B. Between them is built in insert structure for damping, which consists of the plastic part for energy absorption and the elastic part for movement damping. The latter is such a layer structure, which is composed of the 5 rubber plates arranged one above the other and the 6 steel plates lying between and surrounding them.

The 5 rubber plates made of hard rubber and the 6 steel plates can be assembled in a thickness that meets the needs. For the steel mandrels (3), which form the part for energy absorption, there are openings according to the division shown in Figure 2 through which the three mandrels can pass.

In Figure 1 it can be seen that below and above the layer construction that forms the part of the movement damping, there is a 4 base for load distribution, on which the wall construction B is supported on the part for movement damping, the latter on the base body. The 3 steel mandrels do not get directly into the openings formed for them between the base body A and the wall construction B, but they extend into the interior of the bushings 1, which are expediently made of steel tube.

The bushings 1 are surrounded by strong, spatial brackets 7 in at least 2 grooves, by means of which their position is stabilized greater strength. The sockets 1 are therefore now rigidly embedded in the base body A and in the wall construction B.

According to our experimental experience, it is expedient if the bushings 1 extend at least 6 times as deep into the concrete body of the base body A and the wall construction B as their own diameter. Figure 3 shows that the steel mandrels 3 do not extend along the inner part of the bushings 1, but they reach into them at least in a length that is at least five times their diameter.

In this way, an air cushion is created between the lower part 1a of the bushing 1 and the ends 3a of the steel mandrels 3, which can close to a smaller or greater extent as a result of the vertical loads and / or tremors, but also the possibility for locomotion in the axial direction between the steel mandrel 3 and the bushing 1.

Likewise, the possibility of bowage between the part for movement damping and the part for energy absorption is served by the fact that the steel mandrels 3 are loosely traversed by the rubber plates 5, by the steel plates 6 surrounding them, so that the air gaps 8 remain free between their lateral surfaces. Finally, but not least, the slight, telescopic movement of the steel mandrels 3 within the bushes 1 can be facilitated if such a ski material 9 is introduced between the outer lateral surface of the steel mandrels 3 and the inner lateral surface of the bushing 1, which reduces the friction between serves them.

Figure 4 shows the possibility that the steel mandrels 3 along the edges of the insert construction for damping can be replaced by the additional mandrels 10 with less rigidity. In this case, of course, the air gap 8 and the application of the lubricant 9 are not required, but it is expedient to embed the additional mandrel 10 with a smaller diameter in some filler material. The latter can for example made of rubber.

The bushings 1 are expediently prayed in advance both into the base body A and into the turning structure B, and at the same time the spatial reinforcement brackets 7 are finished in the vicinity of the bushings 1. Both in Figure 3 and in Figure 4 it can be seen that the rubber plates 5 and the steel plates 6 are expediently connected to one another by means of adhesive.

In Figure 3, the steel mandrel 3, as well as a thin-walled casing tube 2 for the steel mandrel are housed in the layer construction consisting of the rubber plates 5 and the steel plates 6.

The casing 2 prevents that harmful cuts in the part for energy absorption due to the movements can occur.

Of course, not only one, but also several at Bodarf can be accommodated between the basic body A and the wall construction B from the insert construction for damping shown in Figure 1. The groups of inlay constructions for damping complement their effects with one another, respectively, both their effects of movement damping and their effect on energy absorption are superposed, which means that they function as parallel spring systems.

The inlay construction for damping according to the patent serves to protect buildings in any location that is exposed to seismic movements. It can also be used for special structures such as power plants, smelters, reactors, etc., but there is no need to take into account the horizontal forces that correspond to the wind load or the acceleration values that correspond to these horizontal forces.

Today, the structures are generally planned and calculated based on the stresses of horizontal wind and earthquake forces.

Taking into account the great probability of the maximum wind load, structures are planned and calculated in such a way that all structural elements remain undamaged during the entire service life of the structures in the event of wind load.

Buildings are planned and dimensioned against excessive earthquake forces in such a way that the construction elements cannot be destroyed under seismic loads. However, severe structural damage must be expected.

The main cause of the damage is the process of energy absorption, which ensures the balance of kinetic and potential energy in the construction system throughout the duration of the earthquake.

The cost of avoiding structural damage is around 4-6% of the total construction costs on a global average.

In contrast, the costs after seismic damage multiply when restoring the building or reinforcing it. In severe cases this can amount to 40-60% of the total construction costs.

• 1. Die horizontale Federsteifigkeit des Federsystems muß man so planen und bemessen, daß die bei einem Erdbeben auftretenden horizontalen Kräften und Beanspruchungen, an den Konstruktionen keine größeren Werte als die, die bei maxi- malen Windeffektentauftretenden, erreichen. Das kann ereicht werden, daß bei grösseren Windlasten die horizontalen Kräfte die Federelemente im plastischen Zustand belasten, wodurch an den Konstruktionen nur solche Beschläunigungen entstehen, zu welchem nach Newtonsches Gesetz und d'Alembert's Prizipgleiche seismische Kräfte und Beanspruchungen von Windkräften und Beanspruchungen gehören.
• 2. So ist der ganze Vorgang von Energieabsorbtioneh des Konstruktionssystems unabhängig, da sich die Belastung der Baukörper in den Federelementen verläuft.
• 3. Entsprechende Versuche haben erwiesen, daß die Federelemente zwei aufeinander folgenden Erdbeben der Intensität MSK VIII - IX standhielten, das heißt, die Federelemente besaßen nach einer ersten Belastung noch genügend Festigkeit um bei einem zweiten Belastungsfall die auftretende Energie zu absorptieren. Selbstverständlich ist es ebenfalls möglich, Federelemente für Erdbebenstärke MKS IX - X einzusetzen.
• 4. Im Bauguerschnitt werden die Federelemente so verteilt, daß der Massen- und Steifigkeitsschwerpunkt sowie die Hauptinertia und Hauptsteifigkeitsachse zusammenfallen. So können die Torsionsschwingungen ausgeschlossen werden.
• 5. In speziellen Fällen, wie z.B. bei Kernkraftwerken etc., kann die Federsteifigkeit so bemessen werden, daß keine über dem zugelassenen Maß hinausgehenden seismischen Beanspruchungen auftreten können.
• 6. Allgemein zu den Kosten: Die Kosten,die beim Einsatz der Federelemente zu verzeichnen sind, erreichen in keinem Falle die Kosten für die mit den bisher bekannten Methoden durchgeführten Verhütungsmaßnahmen.

The elastic spring system considered here, which is installed between the foundation and the basement of buildings, is characterized by the following properties:

• 1. The horizontal spring stiffness of the spring system must be planned and dimensioned so that the horizontal forces and stresses that occur during an earthquake on the structures do not reach greater values than those that occur with maximum wind effects. This can be achieved by the fact that with larger wind loads the horizontal forces load the spring elements in the plastic state, which only causes the structures to be slowed down, which, according to Newton's law and d'Alembert's principle, include seismic forces and stresses from wind forces and stresses.
• 2. So the whole process of energy absorption of the construction system is independent, since the load on the structure runs in the spring elements.
• 3. Corresponding tests have shown that the spring elements withstood two successive earthquakes of the intensity MSK VIII - IX, which means that after a first load the spring elements still had sufficient strength to absorb the energy occurring in a second load case. Of course, it is also possible to use spring elements for MKS IX - X earthquake strength.
• 4. In the construction section, the spring elements are distributed in such a way that the center of mass and stiffness as well as the main inertia and main stiffness axis coincide. In this way, the torsional vibrations can be excluded.
• 5. In special cases, such as in nuclear power plants, etc., the spring stiffness can be dimensioned so that no seismic stresses exceeding the permitted level can occur.
• 6. General information about the costs: The costs that can be recorded when using the spring elements never reach the costs for the contraceptive measures carried out with the previously known methods.

When using spring elements, there is no need for a calculation with any restoration or renovation costs, since the forces acting on the structure cannot reach the load values of a maximum wind load.

System definition

• The system consists of: a) sandwich elements to be inserted between the foundation and the structure, which in turn are composed of steel plates and rubber layers glued or vulcanized in between.
• b) steel mandrels inserted perpendicular to the surface of the sandwich elements.

The latter are aukörpergrundplatte by the _B and inserted through the bores of the sandwich elements in the foundation. The guidance of the steel mandrels is guaranteed with the help of the inserted pipe bushings.

The steel mandrels can be replaced if necessary.

In summary it can be explained that the vertical loads are absorbed by the sandwich elements and the horizontal loads by the steel spring elements and also by the sandwich elements.

Claims (13)

1 Inlay construction for vibration damping to reduce seismic forces and stresses that arise in buildings, but it serves to prevent but at least to reduce the transmission of floor movement guards, and it is installed between the foundation and the wall construction, characterized in that the inlay construction increases the resistance of one elastic-plastic spring system is formed, the spring system contains a part for movement damping with great ability of elastic shape change, and a plastic part for energy absorption with great effectiveness, the part for movement damping consists of superimposed rubber plates (5) made of steel plates (6) are surrounded and form a layered structure, the part for energy absorption extends into the opposing surfaces of the foundation (A) and the wall structure (B), it is constructed as a series of steel mandrels (3) that are used for the absorption loads that are greater than the loads resulting from the maximum wind load are unsuitable. 2 Auaführungsform the insert construction according to claim 1, characterized in that the part for movement damping is composed of at least two hard rubber plates (5) and at least three layers of steel plates (6), both on the side of the foundation (A) from the side of the Wall structure (B) of the layer structure formed in this way has a base for load distribution (4). 3 embodiment of the insert construction according to claim 1, characterized in that the foundation (A) as well as the wall construction (B) are now suitable for receiving the steel mandrels (3) of the part for energy absorption, they expediently have bushings (1) which are made of tubular steel. 4 embodiment of the insert construction according to claim 3, characterized in that the bushings (1) are both in the foundation (A) and in the wall structure (B) framed motionless, they are advantageously concreted. 5 embodiment of the insert construction according to claim 3 or 4, characterized in that the bays (1) extend into the foundation (A) and into the wall construction (B) at a depth that is at least four times, advantageously at least six times their diameter. 6 embodiment of the insert construction according to contact points 3 or 4 or 5 - any - characterized in that the steel mandrels (3) reach into the interior of the bushes (1) at a depth that is at least three times, advantageously five times their own diameter . 7 embodiment of the insert construction according to claim 5 or 6, characterized in that an air cushion (12) is left between the ends of the steel mandrels (3) and the lower part (1a) of the bushes (1). 8 embodiment of the insert construction arbitrarily according to one of the claims 1-7, characterized in that the steel mandrels (3) by releasing an advantageous air gap (8) in the layer structure, consisting of Gunmi plates (5) and steel plates (6), loosely pulled through are. 9 embodiment of the insert construction arbitrarily according to one of the contact points 1-8, characterized in that a lubricant (9) is advantageously applied in a thin film to reduce the friction between the outer surface of the steel mandrels and the inner surface of the bushes (1). 10 embodiment of the insert construction arbitrarily according to one of the claims 1-9, characterized in that both the foundation (A) and the wall construction (B) in the vicinity of the concreted sockets (1) in the form of a spatial Bägels (7) has reinforcing inserts. 11 embodiment of the insert construction arbitrarily according to one of the claims 1-10, characterized in that the elastic-plastic spring system swisch foundation (A) and wall construction (B) is installed in sections, and each section contains a part for movement damping and a part for energy absorption . 12 embodiment of the insert construction boliebig according to one of the claims 1-11, characterized in that the steel mandrels (3) are replaced by additional bushings (1a) with lower rigidity at the edges of the entire spring system or, if necessary, at its parts. 13 embodiment of the insert construction according to claim 12, characterized in that the additional bushings (1a) are embedded in an elastic filler material (11).

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