Application of low-invasive techniques and incremental seismic rehabilitation to increase the feasibility and cost-effectiveness of seismic interventions

The high seismic risk connected to the existing construction heritage requires a wide-scale renovation action to ensure structural resilience and avoid future human and economic losses. Given the urgency and the scale of the problem and the lack of available resources, a new strategy for the renovation of the obsolete European building stock should be envisioned, accounting for both safety and environmental, social and economic sustainability. This research aims at exploring new cost-effective seismic retrofit solutions based on the principles of low-invasiveness and incremental seismic rehabilitation, as envisioned by FEMA P-420 (2009). The incremental rehabilitation approach allows to plan repair and retrofit actions along with the maintenance works expected during the building's lifetime, thereby spreading them in time and reducing costs. In addition, low-invasiveness of the solutions is required to reduce the impacts on the functionality of the building, thus cutting the costs connected to downtime. A possible solution is represented by the introduction of an exoskeleton entirely carried out from outside. In this paper, a new sustainable technique is proposed, where the existing structure is connected to a self-supporting exoskeleton adopting demountable dry techniques, which may be assembled and activated in different phases of the building lifetime. As a proof of concept, the approach is then applied to a school building.