Diagrid structures as innovative retrofit solutions for existing Reinforced Concrete buildings

In recent years the redevelopment of the post-World War II reinforced concrete heritage has become an essential action to meet energy-saving and to foster safety and resilience of European communities. In order to overcome the major barriers to the renovation, new solutions should follow a holistic approach, thus solving the structural, energy and architectural deficiency at the same time. The interventions should be carried out from outside the building, so as to leave the building use unaltered, with no need of user relocation, and Life Cycle Thinking (LCT) principles should be addressed. In this paper, these main pillars are translated into an innovative technology, the steel diagrid exoskeleton, for which a proportioning criterion is proposed, besides the assessment of its effectiveness as a seismic risk mitigation measure. Among possible structural typologies, diagrids are particularly interesting for their remarkable architectural potential and for the possible standardization of the components.