A new integrated approach on the seismic strengthening of existing RC buildings with external cross-laminated timber panels

In this study a timber-based integrated solution is presented to solve at once common issues affecting typical reinforced concrete (RC) existing buildings, such as seismic and energy performances, providing an eco-friendly alternative to steel external bracing systems. Cross-laminated timber (CLT) walls are provided perpendicularly to the external façades as strengthening elements while interposed CLT slabs are foreseen at each floor level to host new architectural units together with a new envelope. While the connections to the foundations and to the existing RC frames are provided respectively with steel brackets and simple axial-connectors distributed along the height of the building, a post-tensioned connection, between CLT panels (PT-CLT connection), is implemented in the system to guarantee resistance to horizontal actions acting parallel to existing façades with consequent structural independence and architectural freedom. A numerical model is developed with finite element software and non-linear static analyses with target displacement checks are performed to assess the seismic improvement obtained. Finally, the preassembled architectural components that allow to renovate the envelope and the provided assembly procedure are revealed.