Dissipative exoskeletons for seismic rehabilitation of RC buildings

Relevant buildings like schools, public offices, assembly halls, and so on, should retain their structural integrity since their collapse could cause major human losses and significant economic impact. Moreover, such buildings should remain operational even during seismic retrofit work. This has stimulated the development of seismic retrofit solutions based on rapid, low-impact, and reversible interventions that can be done while the building is in use, removed and rapidly replaced if damaged due to earthquake, and integrated with energy efficiency measures. This situation has encouraged the use of external additive structures, commonly called exoskeletons, as a feasible solution for seismic retrofit. Typically, the research and applications deal with non-dissipative steel exoskeletons based on diagonal grids (diagrids) or external braces. This paper outlines the design and evaluation of dissipative exoskeletons. It focuses on a real school building case study, where both parallel and orthogonal exoskeleton configurations are employed. The dissipative exoskeletons are designed using a displacement-based design procedure. The effectiveness of the retrofit strategy is finally demonstrated by nonlinear time-history analyses under different sets of earthquake-strong ground motions.