"DEVICE FOR REACTIVE INSULATION FROM ALTERNATE HORIZONTAL DYNAMIC STRESSES"

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FIELD OF THE INVENTION The device according to the present invention adopts the principle of mechanical reactivity and is conceived to attenuate the vibratory energy that is propagated in a horizontal direction. The most common sources of horizontal vibrations comprise, apart from earthquakes, weaving looms, mechanical presses, rolling mills and centrifuges. BACKGROUND OF THE INVENTION

The chapter in Physics that deals with the use of the device according to the present invention is: Dynamics of mechanical vibrations, which also deals with phenomena connected with the propagation of vibratory energy, that is, elastic waves. This chapter develops two topics, which are: a) how to promote the vibratory state, when it is desired to use its action in the technological field; b) how to defend oneself from the action of the vibratory state when damage derives for the health of people, or the integrity of their goods. From this second point of view, the attenuation of vibratory energy always requires, functioning as a protective barrier, the use of those mechanical devices called vibration-dampers. The great morphological variety available on the market meets the specific uses for which they are adopted: in some cases the physical principle of dissipatability, which converts mechanical energy into thermal energy, or, in other cases, the physical principle of mechanical reactivity, by means of which reflection of the wave front is produced, in the same way as happens for images put in front of a semi-reflecting surface.

Applicants are not aware that there exists another type of reactive vibration-damper for horizontal vibratory fields, to protect building structures that are built on ground passed through by seismic waves, or, in subordination, by wave fronts generated by machines having great masses subject to alternate horizontal movements.

In the building field, techniques for constructing a building are known. The buildings are usually constructed so as to be solid with the ground, so that when they are hit by alternate horizontal dynamic stresses produced by an earthquake, they oscillate, with the relative consequences. Moreover, in every other case too where energy is propagated through alternate horizontal dynamic stresses, the ground transmits them entirely to the building.

A building made with traditional techniques cannot be considered protected when it is entrusted to traditional techniques alone, so that all the structures that make up such a building are subject to the risk of collapse.

The absence of insulation between a building and the ground on which it stands causes the same disadvantages, but directed in the opposite direction, when the vibratory stresses produced by machinery as per the previous paragraph, tend to spread in the surrounding environment. It is obvious that in cases like these it is much more simple and economical to adopt insulation of the sources of the vibration stresses, that is, the machinery, with respect to the bearing structures. The Applicants believe that the invention here proposed is the most effective insulator of stresses propagated horizontally.

The idea of the device according to the present invention proposed by the Applicants originates in the impression caused by catastrophes produced by earthquakes and in particular earthquakes of an undulatory nature, which are the most destructive. The concept of the invention proposed by Applicants finds no correspondence or connection in any other device intended for the limited variety of anti-seismic devices existing and used until now.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the main claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

For the reasons set forth above, the operating efficiency of the present invention is suitable both for the condition that sees the structure

threatened by the vibrations transmitted by an earthquake or similar phenomenon, and also the condition that puts the surrounding environment exempt from the vibrations produced inside a structure where the sources of the vibrations are installed. The suitable configuration in any case provides that the plane of the ground and the plane of the structure base are parallel. The distance between these planes corresponds to the vertical bulk of the vibration- damper device or devices according to the present invention installed, which perform their task by keeping the distance between the parallel planes substantially unvaried.

According to a characteristic of the present invention, each individual device comprises a first element (upper face) to be attached to the structure, a second element (lower face) associated with the supporting base and also tie rod elements which connect the two elements to each other.

The tie rods here and hereafter shall be understood as elements intended for connection functions and stressed under traction.

Each device according to the present invention is structured to support a certain maximum load and the structuring of the various components described above will be characterized by its own frequency connected to the length of the tie rods used. The characteristic frequency remains constant, irrespective of the load, provided it is maintained within the maximum load capacity of each individual device. This frequency must be chosen lower than that of the forcing vibrations and, to put it better, much lower, in observance of the principle of mechanical reactivity. Also in those cases where the forcing frequency is in the range of 10 c/sec (as for the strongest undulatory waves of earthquakes, which we are dealing with here), the device according to the present invention is able to ensure attenuations of more than 90%. To give an example, an earthquake classified as the maximum degree of the Richter scale would produce effects lower than those of the first degree.

BRIEF DESCRIPTION OF THE DRAWINGS These and other characteristics of the present invention will become

apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a plane view of a device according to the present invention for reactive insulation from alternate horizontal dynamic stresses;

- fig. 2 is a section of the device from Il to Il of fig. 1.

DETAILED DESCRIPTION OF A PREFERENTIAL

FORM OF EMBODIMENT

With reference to the attached figs. 1 and 2, each device or support 10 according to the present invention will be made with the characteristics relating to its maximum load capacity and its own characteristic frequency.

In the case of loads higher than that supported by an individual element, several identical elements will have to be used, disposed parallel, in a position established by the design engineer. The attachment of the faces of the device 10 and the surfaces of the base and of the structure can be achieved by means of clamping or friction.

There are generally three tie rods 12 which connect the two elements

14 and 16 of the insulating device 10, equidistant from each other, along a circumference, or along several concentric circumferences, given that the number of tie rods 12 can be as many as desired. Alternatively, a single tie rod 12 can be provided, disposed at the center of the device 10.

In any case, the individual tie rod or tie rods 12, in quiet conditions, will have a vertical position. The quantity of tie rods 12 adopted must be related to the constructional characteristics of the device 10, and also the positioning thereof, which will be along a circumference whose diameter will be equal for the two elements 14 and 16 of the device 10. The tie rods

12 can be made with a rectilinear development of formed by rings connected in a chain. Their length determines the frequency of the device 10. At the two ends they are connected to the elements 14 and 16 of the device 10 by means of punctiform-contact articulated joints, so as to allow the two elements 14 and 16 of the device 10 full freedom of movement in any horizontal direction. With this choice, in its anti-seismic function, the

lower element 16 remains subject to the forcing stress, while the upper element 14 will remain substantially still.

The overall load of the structure to be insulated will be shared on an adequate number of supports by adopting a rigid platform, while the vibration-damper supports must be positioned on a rigid bed, able to allow the structure to float on the ground beneath.

Moreover, according to a variant, not shown in the drawings, the device

10 can be an integral part of the structure to be protected, so that the same structure is directly connected to the tie rods 12, which are fixed to holding elements, or pivots, connected to the ground affected by the stresses.

It is clear that modifications and/or additions of parts may be made to the device 10 as described heretofore, without departing from the field and scope of the present invention. For example, buffer elements and/or shock-absorber elements may be provided.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of devices suitable for reactive insulation from alternate horizontal dynamic stresses, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.