All-steel external frame for the non-disruptive seismic retrofit of existing reinforced concrete buildings

The state-of-the-art review in seismic retrofit of existing reinforced-concrete (RC) buildings indicates that a technology that isnon-disruptive and easy to implement, achieves simultaneous control of drifts and accelerations, and overcomes majorissues related to low concrete strength, poor reinforcement details, and vulnerable RC columns, has never been described inthe literature or in seismic design codes (e.g.

Eurocode 8).

The ambitious main objective against the background of thestate-of-the-art of the project is to develop such a retrofit technology.

In particular, the project will develop a non-disruptiveretrofit scheme using an external, modular, steel frame as a facade close and in parallel connected to frames of the existingRC building.

The external steel frame will have chevron braces to support energy dissipation devices, and, connectors toachieve horizontal coupling with the existing RC building.

Strategically, the energy dissipation devices will be visco-plasticdampers, i.e. novel devices that will offer visco-elastic damping output under low-to-moderate earthquake intensities andfriction damping output with a predefined limit on their peak force under high seismic intensities.

The project will developsophisticated yet practical structural details and a simplified seismic design procedure for the external steel frame.

All thesewill be achieved through a carefully planned integrated experimental and numerical research program involving constitutivemodelling, nonlinear finite element analysis, and shaking table tests.

The proposed retrofit scheme constitutes a solidcontribution to earthquake engineering that is expected to raise major international scientific and industrial interest.