Seismic isolation

Seismic isolation of buildings

Upgrade to seismic standards an existing building is undoubtedly more complex than designing a new type of anti-seismic building and involves a cost that makes often more convenient the demolition and reconstruction of the structure.

One of the ways to intervene on existing assets is to implement seismic isolation devices, which allow buildings to withstand earthquakes also destructive.
In this case, the intervention is confined almost exclusively to the plane of the foundations and it is not necessary to carry out particular interventions for elevated structures.

It is a passive isolation technology by earthquakes relatively new but very popular in countries like Japan, while in Italy are still a few isolated buildings, despite the seismic classification of the territory.
A significant example is the construction of the CASE project, started in L'Aquila for the post-earthquake reconstruction.

Of course the technology is applicable, and indeed it is desirable to use, even in new buildings.

But how does the seismic isolation work? The ideal condition would be to be able to realize a sort of air cushion so as to completely isolate the building from the ground and its movement during the earthquake. Where this is not possible, the technology plan to isolate the structure from entering the building and its foundations of seismic isolators, which are used as platforms for the CASE project also apply to historic buildings.

Seismic isolators

There are three basic types of seismic isolators:
-rubber bearings;
-sliding isolators;
- insulator metal rolling.

They are essentially constituted by a series of steel plates immersed in an elastic matrix with high sliding, with or without lead core or sliding.

Their presence ensures that the isolated structure behaves during an earthquake, almost like a rigid body, thus remaining independent from the movements of the surrounding terrain.

The interesting thing is that, if the phases of the work are properly designed, in the case of existing buildings can still be used during the intervention.

For those interested to intervene on the structure of their building to improve safety it is advisable to turn to designers and construction companies capable of providing complete support for the choice of the most suitable system (in fact there are other systems of protection from the earthquake, as the energy dissipating devices and dynamic constraint).

De.La.Be.Ch. Construction Ltd., for example, is able to follow the intervention from the calculation of the structure under the action of the earthquake, the design of the most suitable system for seismic protection, until of course the final design of the seismic devices chosen for their provision and installation.

The SAP Studio Engineering srl is instead a company specialized in structural design, which from the beginning has been dedicated to interventions of seismic retrofitting of considerable complexity with the application of innovative methods such as seismic isolation.

Benefits of seismic isolation

With the seismic isolation building you get a dual purpose: on the one hand the building does not collapse, and then you save lives, the other will also preserve the same components of the building (structures, systems, curtain walls, etc.).

In fact, a common seismic structure preserves the building from collapse, but will not let it immune to damage also considerable. Instead, with a seismically isolated building, the damage is greatly limited, so it retains its full usability. That's why the technology is very interesting for public utility buildings.

How much seismic isolation of a building?

The cost of seismic isolation of a new building not primarily affect the overall costs. It is equal to about 5% of the total cost (in practice the same incidence of the price of an electrical installation).

In the case of retrofitting an existing building, however, it can be estimated incidence of costs between 50 and 150 euro per square meter of floor area of the building.

In any case, the additional costs compared to a building not isolated, we saw at least have a minimum percentage, are largely offset from getting real protection from the risk of earthquakes.

Incidentally, in recent times, were built in China seismically isolated buildings, where the higher cost spent to insulate the foundation works, was compensated by the lowest one that was necessary to spend for those in elevation.
It is, therefore, to a future of isolated buildings from the earthquake and also convenient from an economic standpoint.