The invention is a mechanical device that strongly reduces the magnitude of vibrations when it is installed on civil and industrial structures exposed to dynamic loading, thereby improving both the safety level and the serviceability conditions. The device belongs to the class of tuned-mass dampers and consists of a small oscillating mass connected to the structure by steel or shape memory wire ropes with super-elastic behaviour. When the structure to be protected is excited, the kinetic energy is transferred to the mass of the device that oscillate with respect to the structure and applies on it a restoring forces able to reduce its motion.
Patent Status
GRANTED
Priority Number
102015902332343
Priority Date
20/02/2015
License
INTERNATIONAL
Market
The technology specialized for civil constructions is targeted to a very wide market. A recent survey shows that about 80% of the housing stock in Italy dates to 1975 or earlier. About 1 million buildings in the country is exposed to seismic hazard and require significant structural retrofitting according to current safety standards. Within this framework, the use of conventional retrofitting techniques is not always feasible because of economic reasons and/or architectural constraints, especially in historic centres and in urban aggregates with high population density.
Problem
Earthquakes release huge amounts of energy that transfer to bridges, buildings and other structures, which respond in an oscillatory and complex way. The first cycles of movement are generally higher and are often amplified by the phenomenon of resonance. In the cyclic response phase, structures can be severely damaged or even collapse due to the inability of the structural system to sustain the transferred energy, which is transformed into excessive levels of irrecoverable strain energy. Therefore, if such structures are resilient enough and capable of dissipating the input energy in an proper way, then they may continue to oscillate until the quietness condition or, if the action lasts for a long time, they achieve the condition of stationary resonance characterized by a periodic balance between the input energy and the dissipated energy. A suitable approach towards the problem of controlling the seismic response requires that the structure is designed to be able to dissipate the input seismic energy. The classic approach is to size the structure in such a way that it can internally dissipate the energy received by transforming only a part of it into kinetic energy. This implies a significant oversizing that is not compatible with the minimum cost criterion and the need of reducing the environmental impact of the building sector. The proposed technology allows to retrofit some types of existing buildings as well as to build new high-performance slender structures.
Technological limits/ Solutions
A technique for the reduction of the seismic risk consists in the base isolation where the structure is made free to move with respect to the ground in such a way that all the components move of the same quantity and therefore are not subject to internal deformation. In any case, the kinetic energy transferred to the structure must be limited to avoid reaching the limit displacement of the isolation devices, and the structure is subject to extreme stresses. This methodology is expensive because it requires a double foundation and can be easily applied only to new buildings. The isolation devices, in addition to allowing relative displacements, must also guarantee a suitable level of energy dissipation while ensuring that the structure reaches a quiet condition in the position in which it was originally. Another technique consists in the introduction of internal dampers able to dissipate the excess energy. The dampers internally concentrate the dissipation of the kinetic energy transmitted to the structure. However, the application of this technique in existing buildings presents considerable installation costs and poses architectonic issues along with high costs in the post-earthquake phase due to dampers replacement.
Killer Application
The main applications of the technology are:
In particular, the implementation form of the technology under development is designed to reduce the seismic risk of multi-storey reinforced concrete and steel buildings.
Technology and our solution
The targeted application aims at reducing the seismic risk of public and private buildings that have structural features such as to make the intervention effective and sustainable from an economic standpoint. Special attention will be paid on reinforced concrete buildings built before 2000 with a number of floors higher than 5 and which have a small tower floor reached by the reinforced concrete core that contains the elevator. On the latter it is possible to place two devices, each with a mass equal to only 1% of the building, that can reduce by more than 60% the oscillations induced by earthquakes. The intervention is implemented by installing auxiliary structures for the connection and eventual reinforcements only on the structural elements of the last floor, thus, the usability of residential units is not compromised. Economic commitment is strongly competitive because of the components that make up the technology and the production process as well as its passive nature (does not require electricity energy) and especially if you make the comparison with invasive techniques that intervene on all the structural elements of the building.
Advantages
The main advantages are the followings.
Roadmap
A Start Up is being set up in order to reach the mark. The following activities are planned for the next 3 years:
TRL
Team
