Application of Crescent-Shaped Brace passive resisting system as a retrofitting system in existing multi-storey frame structures

Generally, existing structures do not satisfy the current design codes, nor do they fulfil the performance objectives under rare ground motion levels. This poses the necessity of controlling such structures, as the risk they impose is high. Among different solutions, we present an application of an innovative energy dissipation device, namely Crescent-Shaped Brace (CSB), in existing multi-storey shear-type structures. CSB can be a superior retrofitting system for existing buildings in order to ensure they are compatible with the modern design norms. CSBs have a unique geometric configuration that allows controlling the behavior of the structure to satisfy predefined seismic performances under different ground motion levels. In this paper, we propose an exhaustive procedure for the seismic design of the CSB devices within the Performance-Based Seismic Design (PBSD) framework. The seismic behavior of an existing three-storey reinforced concrete structure equipped with the CSB devices is studied and verified by means of static pushover and dynamic time-history analyses. The results obtained confirm the validity of the proposed design method and the efficiency of the new hysteretic device. The actual behavior of the controlled structure matches the predefined behavior, thus fulfilling of the prescribed multi-seismic performances.