Speaker
Description
Seismic isolation and/or supplemental energy dissipation is used in Italy since the 1970s in new structures. However, the applications of these technologies in existing buildings became relatively common after the destructive 2009 L'Aquila earthquake.
Seismic isolation, when feasible, is the most effective retrofit technique, thanks to strong reduction of accelerations and interstorey drifts, and the removal of torsional problems. Seismic isolation was applied in many buildings damaged by recent earthquakes, but not so damaged to make more affordable demolition and rebuilding. The Italian reconstruction law imposes that the retrofit of buildings strongly damaged by an earthquake improves the seismic behaviour at least at a level of 60% of the performance of a new building on the same site. It is not easy to reach this level with conventional techniques, while seismic isolation allows to reach even higher levels without works on the superstructure. This makes seismic isolation ideal to retrofit undamaged buildings as well, without interrupting their use, apart in a small portion (usually basement or ground floor).
Supplemental energy dissipation devices are also very useful to retrofit existing buildings. They reduce the request of ductility to existing structural elements, and thus reduces their damage. The structures that benefit most from supplemental energy dissipation are framed buildings that are too flexible as well as to weak under seismic actions. Energy dissipation devices are often used in braces, to exploit the excessive interstorey drifts of said buildings. However, there could be other positions for the installation of energy dissipation devices. The lecture presents many practical examples of use of seismic isolation and energy dissipation devices in existing buildings in Italy.
