Seismic improvement and retrofitting of existing Italian buildings cannot always be an easy problem to solve. In fact, several traditional intervention techniques exist but each one of them is related to practical difficulties in its implementation, since they often involve invasive building activities and inconvenience to the occupants.

With the aim of proposing an innovative solution to the problem, ISAAC has developed, patented and tested an active control technology, already introduced by the ISO 3010:2017 standard as Active Mass Damper (AMD). It consists in the use of inertial forces, generated by the active movement of mobile masses installed on the roof of the building, to counteract its oscillations during the seismic event and to limit the expected damage to structural and non-structural elements. This type of intervention gives the possibility of increasing the seismic and dynamic performance of the building acting only externally, quickly and without causing disturbance to residents.

The system was tested with experimental tests on a shaking table at the EUCENTRE laboratories in Pavia, which allowed the validation of the technology and the development of software and best practices for FEM modelling techniques of the structural behavior considering the AMD system.  

The paper also presents the case of application of the active control system on a 14-storey residential building with precast reinforced concrete load-bearing wall structure. After a brief description of the construction system of the building, the material investigation campaign and the dynamic identification tests carried out are illustrated. Afterwards, the design and analysis method for the retrofit intervention with AMD technology is described, highlighting the achievable seismic performance improvement.