FAQ · FREQUENTLY ASKED QUESTIONS

ISAAC systems are an active control system that exerts forces on the building, according to instructions received from a central computer; the latter constantly detects the accelerations felt by the structure, thanks to the sensor system, and processes them through a control algorithm. If an earthquake strikes, the system starts operating independently, to prevent damage to the building.

Machines are installed on the roof of the building (or on the uppermost flat surface) to obtain the maximum improvement in the structural performance of the construction in the event of an earthquake. After installing the machines and connecting them to the motion sensors and the central control computer, the system becomes operational. If an earthquake strikes, the central computer detects the movement through the sensors and, thanks to the control algorithms, defines the movement and the force delivered to the building from each installed machine, so as to minimize the displacements of the structure and maximize dissipation of the energy introduced by the earthquake.

The number of machines to be installed to obtain the desired earthquake-resistant improvement is defined based on the building’s size and the number of floors. This allows for obtaining improved performance in all reference limit states for the building (SLO, SLD, SLV, SLC).

If the roof slab cannot withstand the vertical load of the devices, and in any case to ensure proper distribution of horizontal forces on vertical structural elements (such as walls or columns), it is recommended to design a small metal structure to support and distribute the load.

The benefits of adopting ISAAC systems for the end user are:

• Minimum invasiveness of the earthquake protection intervention.
• Reduced intervention times on the structure.
• No downtime for the building or its occupants, since systems are installed on the roof, by intervening only from the outside rather than the inside.
• The greater the extension and performance to provide to the building, the higher the savings on the total cost of the intervention compared to using traditional reinforcement techniques.

Yes, the systems can be applied in all earthquake zones. Obviously, at other sites with varying earthquake risk, it is necessary to vary the number of devices installed, depending on the risk protection you want to achieve.

The AMDs proposed by ISAAC are composed of longitudinal guides along which the moving mass can oscillate horizontally. For this reason, the systems are able to withstand the effects of only transverse waves on the structure that propagate in the ground. Unlike transverse waves, vertical waves produce much smaller effects on buildings and are almost always negligible to the safety checks on structural elements. These types of waves produce significant earthquake stresses only in certain types of structures (bridges, long spans, unstable structures) and must be taken into account in the project, as established by the Technical Regulations for Construction.

No, TMDs (Tuned Mass Dampers) are passive type tuned mass devices. On the other hand, ISAAC systems are active control systems (AMD, Active Mass Dampers).