INODIS – A Novel Decoupling System to Improve the Earthquake Resistance of Masonry Infills

Masonry infills are widely used as internal and external partitions in reinforced concrete frame structures. However, recent earthquakes have revealed that the interaction between masonry infills and RC frames often leads to severe, uncontrolled damage, highlighting their high seismic vulnerability. Such damage not only results in significant economic losses but also poses serious risks to human safety. The poor seismic performance of masonry infills underscores the urgent need for effective mitigation strategies. This contribution introduces the innovative decoupling system INODIS designed to isolate masonry infills from the surrounding RC frame. The proposed solution involves inserting recycled elastomeric strips between the infills and the frame, thereby delaying the activation of the infills under in-plane seismic loading while still offering support against out-of-plane forces. Cyclic static experimental tests were conducted on RC frames with both rigidly connected and decoupled infills, including configurations with and without openings. The results demonstrate a significant improvement in the seismic performance of masonry infills when the decoupling system is applied. Furthermore, the system was validated by shaking table tests under real earthquake excitation. Finally, a simple and safe design concept based implemented in the second generation of Eurocode 8 is presented and applied to a typical RC frame structure.