ITMI982839A1 - DISSIPATOR AND LOAD LIMITER DEVICE FOR THE PROTECTION, RESTORATION AND REALIZATION OF HIGH-CIVIL AND INDUSTRIAL WORKS - Google Patents

Description

Description of the Patent for Industrial Invention entitled: "DISSIPATOR AND LOAD LIMITER DEVICE FOR THE PROTECTION, RESTORATION AND CONSTRUCTION OF CIVIL AND INDUSTRIAL WORKS WITH HIGH RESISTANCE AGAINST UNDESIRABLE STATIC EFFECTS, SEISMIC, WIND AND DYNAMIC EFFECTS IN GENERAL"

DESCRIPTION

The present invention relates to a heat sink and load limiter device for the protection, restoration and construction of civil and industrial works with high resistance against undesirable static effects, seismic, wind and dynamic effects in general.

As is known, in the civil and industrial construction sector and in the historical monuments sector, more and more attention is paid to the protection of structures from infrequent but predictable events, such as earthquakes, wind storms and any other dynamic effect that induces vibrations.

These structures must safely resist the aforementioned load conditions, possibly without appreciable structural damage.

Furthermore, all those phenomena of non-dynamic origin which impose undesired deformations to the structures should not be neglected.

Currently, unfortunately, almost all of the structures already built, both of historical and civil and economic interest, have not been designed and built to withstand these events and have shown their inadequacy in the past.

The aim of the invention is to eliminate the aforementioned drawbacks, realizing a heat sink and load limiter device, which gives the possibility of improving stability and increasing the damping of vibrations, with the possibility of connecting two or more structural elements. in possible relative motion to dampen the motion itself and limit its displacement.

Within the scope of the above aim, a particular object of the invention is to provide a technology that is easy to apply, since the devices used can be extremely compact and / or easy to conceal, thus also obviating the architectural limits imposed by the designer. .

In addition, the material used has excellent resistance to atmospheric aggression.

Another object of the present invention is to provide a dissipator which allows to limit the load transmitted to its ends, if a deformation is imposed, and which, moreover, can limit the displacement exceeding the maximum design value, with the possibility of orienting according to the direction required by the structure by means of anchoring joints and / or its flexibility.

The present dissipating device has a characteristic operating stability even when the temperature and frequency of application of the load vary.

The aforementioned task, as well as the aforementioned and other purposes, which will appear better highlighted later, are achieved by a heat sink and load limiter device for the protection, restoration and construction of civil and industrial works, with high resistance against static effects. undesirable, seismic, wind and dynamic effects in general, according to the invention, characterized by the fact of comprising a plurality of shape memory alloy wires exploiting the super-elastic effect and interconnected, at the ends, to elements for connection to the structure to be protected .

Further characteristics and advantages will be better highlighted through an examination of the description of a preferred, but not exclusive, embodiment of a heat sink and load limiter device, illustrated as an indication, but not limited to, with the aid of the attached drawings, in which:

Figure 1 is a schematic view of the load dissipating device, seen in section;

Figure 2 is a graph showing the axial tension as a function of the percentage deformation;

Figure 3 is a graph of the force as a function of the displacement;

figure 4 represents a device with a bellows for containing the fluid;

Figures 5a, 5b and 5c represent characteristic curves obtainable with the device in question and with a further arrangement of the wires in S.M.A. with super elastic effect;

figure 6 represents a configuration in which the wires, being pretended, for any relative displacement imposed on the anchoring ends, are always deformed under traction and react according to the characteristic curve already illustrated in figure 2.

With particular reference to the aforementioned figures, the dissipating and load limiting device for the protection, restoration and construction of high-resistance civil and industrial works with three undesirable static effects, seismic, wind and dynamic effects in general, according to the invention, which is indicated in figure 1 as a whole with the reference number 1, comprises a plurality of wires 2 made of shape memory alloy exploiting the super-elastic effect, which are arranged side by side, so that the individual wires work in parallel to exercise the reaction envisaged by the project; the length of the wires is determined on the basis of the design displacement.

At the ends, the wires 2 are connected to locking elements, globally indicated with the reference number 3, which are connected to joints or connection elements 4, to allow the system to be applied to the structures and to perform the possible stringing.

The locking elements consist of a conical locking wedge 10, which is inserted in a jacket 11 with a conical internal surface, between which the ends of the threads 2 are interposed; the wedge and the jacket are made of a material having a surface hardness lower than that of the threads, so that the internal conical wedge, having a lower hardness, is forced into the seat, locking the threads.

Furthermore, a cup-shaped element 12 is provided which contains the jacket and the wedge and is fixed to the connection elements which can, for example, consist of a hooking rod.

If it is necessary to withstand very high frequencies, the wires 2 are immersed in a liquid, in a grease or gel, having high thermal transmissibility characteristics and in particular having thermal transmissibility equal to or better than ethylene glycol.

For this purpose, a bellows 20 is provided for containing the liquid or fluid, identified with 21.

The behavior of the device depends on the thermo-mechanical characteristics of the shape memory alloy, used and installed in the form of wires.

Figure 2 shows a typical graph concerning the mechanical characteristics of the wires used and describing the superelastic effect obtained by subjecting a sample of wire to an axial deformation.

The material, initially in the austenitic phase, shows an elastic phase, which corresponds to a proportionality between stress and deformation.

Once a critical deformation ∈A has been reached, the transformation of austenite into martensite begins, which corresponds to an almost constant tension until the transformation that occurs at a critical deformation ∈M is completed.

This deformation field ∈A - ∈M, in which the phase transformation takes place, can be used for the intended purposes.

In fact, in this characteristic interval, if the applied load is removed, the material tends to return to its undeformed position, exerting an elastic return due to the martensite-austenite transformation according to the lower curve of the pseudohysteretic cycle, illustrated in figure 2.

The cycle in Figure 2 represents the energy dissipated per unit of volume by the material used and can easily be transformed into the characteristic curve of the complete limiting device, knowing the number, diameter and length of the wires used, as illustrated in Figure 3.

The device in question is commonly designed to work in the range of movement SA ÷ SM at a force level included in the range F1 ÷ F2.

The device can be claimed at the design strength level by imposing a displacement S <*> corresponding to the predetermined deformation ∈ <*> in the interval ∈A ÷ ∈M.

This pretension allows immediate activation of the dissipative effect of the device according to the characteristic curve of Figure 3, for any displacement imposed on the structure.

If the deformation of the wires exceeds the value ∈M, the wire, completely in the martensitic phase, would show a sudden stiffening up to the deformation corresponding to the yielding of the martensite ∈Y, which would be followed by plasticization with a partial hardening of the material until failure ∈R .

The stress corresponding to the deformation ∈Y, much greater than the austenite-martensite transformation stress, thus provides a safety factor that is always very high both on yield and on failure.

The progressive stiffening effect corresponding to deformations greater than ∈M, can be used to limit the displacements of the structure in which the device is applied, thus preventing unexpected deformations of the structure.

As previously mentioned, in case of vibrations with frequencies higher than or equal to 1 Hertz, it is convenient to immerse the wires in shape memory material in a fluid (grease or gel) such as ethylene glycol, which has the function of disposing of external heat that is produced.

The invention, thus conceived, is susceptible of numerous modifications and variations, all falling within the scope of the inventive concept.

Furthermore, all the details can be replaced by other technically equivalent elements.

Thus, for example, even if a conical wedge has been expressly mentioned in the locking elements, it is possible, using the same principle, to use a prismatic wedge configuration.

A further arrangement of the super-elastic effect SMA wires can provide a characteristic curve of the device among those illustrated in Figure 5 (Figures 5a, 5b and 5c).

In fact, according to this configuration (see figure 6), the wires, being expected to have a deformation level ε <*> with 0≤ε <*> <εΜ, for any relative displacement imposed on the anchoring ends will always be deformed under tension and they will react according to the characteristic curve already illustrated in figure 2.

In the latter case, the wires (figure 6 - type 1 elements) are wound during assembly on spools (figure 6 - type 2 elements) which are threaded onto the respective pins (figure 6 - type 3 elements).

The assembly of the spools, whose center-to-center distance will be suitably equal to or less than that between the respective pins, on the latter can only take place by stretching the wires and therefore deforming them to increase the center-to-center distance to the size existing between the pins.

A deformation ε <*> of the wires in question will correspond to this dimensional difference between the center distances.

If it is convenient, the pin-spool system can also consist of a single monolithic element, in order to allow simple assembly.

The anchoring carpentry (figure 6 - elements type 4 and 5) must be suitably slotted, in order to allow both the mechanical contrast stop on a pin, and the dragging movement imposed on the other pin.

This device will allow the wires to always be stressed by traction, for any relative movement imposed on the ends of the device.

This system, like the previous one, may provide, for operation at frequencies higher than 1 Hz, the immersion of the wires in an appropriate medium (Figure 6 - element type 6).

Furthermore, the anchoring of the wires shown in figure 6 can be replaced by the type described above using the wedge system. The anchoring details of the system to the structure can be defined from time to time, to better adapt to the structural type considered.

What makes this invention interesting is that, unlike the first system, it does not need to be required on site or in any case when it is applied to the structure, since the wires are required during assembly.

It is necessary to emphasize that the device does not impose any effort on the structure, being internally self-balanced.

The same reacts only when a relative shift is imposed.

Claims (16)

R I V E N D I C A Z I O N I 1. Heatsink and load limiter device for the protection, restoration and construction of civil and industrial works with high resistance against undesirable static effects, seismic, wind and dynamic effects in general, characterized by the fact that it comprises a plurality of alloy wires shape memory exploiting the super-elastic effect and interconnected, at the ends, to connection elements to the structure to be protected. 2. Heatsink and load limiter device, according to the preceding claim, characterized in that it comprises, at the ends of the aforesaid wires, locking elements for connection to said connection elements. 3. Heatsink and load limiting device, according to the preceding claims, characterized in that the aforesaid locking elements have a conical locking wedge introduced into a jacket with a conical internal surface, said wedge and said jacket being made of material with surface hardness lower than that of said wires. 4. Heat sink and load limiter device, according to one or more preceding claims, characterized in that it comprises a socket for containing said jacket and said wedge, said socket being associated with said connection elements. 5. Heatsink and load limiter device, according to one or more preceding claims, characterized in that it comprises a delimited space around the wires for containing a fluid, grease or gel with thermal transmissibility characteristics equal to or greater than ethylene glycol, for operation at frequencies greater than or equal to 1 Hertz. 6. Heatsink and load limiter device, according to one or more preceding claims, characterized in that it comprises a bellows connected, at its ends, to the locking elements and containing said fluid. 7. Heatsink and load limiter device, according to one or more preceding claims, characterized in that in it the wires are wound in the assembly phase on spools, which are inserted on the respective pins. 8. Heatsink and load limiter device, according to one or more preceding claims, characterized by the fact that it is provided with spools, the center distance of which is equal to or less than that of the respective pins, whose assembly on the pins can take place by stretching the wires and therefore deforming them until the distance between centers is increased to the dimension existing between the pins. 9. Heatsink and load limiter device, according to the preceding claim, characterized in that a deformation of the aforementioned wires corresponds to this dimensional difference between the center distances. 10. Heatsink and load limiter device, according to one or more preceding claims, characterized in that the pin-spool system can also consist of a single monolithic element. 11. Heatsink and load limiter device, according to one or more preceding claims, characterized in that the anchoring structures are suitably slotted in it, so as to allow both the mechanical contrast stop on a pin and the dragging movement imposed on the other pivot. 12. Heatsink and load limiting device, according to one or more preceding claims, characterized by the fact that the same provides that the wires are subjected to traction for any relative displacement imposed on the ends of the device itself. 13. Heatsink and load limiter device, according to one or more preceding claims, characterized in that the same, for operation at frequencies higher than one Hz, provides for the immersion of the wires in an appropriate medium. 14. Heatsink and load limiter device, according to one or more previous claims, characterized in that the anchoring of the wires in it consists of a wedge system. 15. Heatsink and load limiter device, according to one or more preceding claims, characterized by the fact that it is structurally structured so that the wires are required during assembly and that the same device does not impose any effort on the structure, being internally self-balanced, so as to react only when a relative shift is imposed. 16. Heatsink and load limiter device for the protection, restoration and construction of civil and industrial works with high resistance against undesirable static effects, seismic, wind and dynamic effects in general, according to the preceding claims, all as more fully described and illustrated and for the specified purposes.