Energy-based method to design hysteretic bracings for the seismic rehabilitation of low-to-medium rise RC frames

In this study an energy-based method for the design of passive Energy Dissipative Bracing (EDB) systems is presented, as a retrofit technique for existing reinforced concrete buildings. A comprehensive literature overview concerning the design of hysteretic bracing systems based on various design philosophies, such as force-, displacement- or energy-based, is provided. The proposed method is suitable for low to medium height buildings which exhibit shear-type behaviour. The procedure is based on the principle of optimum strength distribution that enables the distribution of damage/energy and avoids its concentration at a single storey. Initially the design strength of EDB system at the base is determined and subsequently the strength of storeys above is evaluated through a shear coefficient obtained from numerical analysis. The efficiency of the proposed method is verified by performing non-linear static and non-linear dynamic analysis of three reinforced concrete frames designed with obsolete codes of pre-1980s. Furthermore, the results of the proposed method are compared with two other procedures selected in the literature. The validity of each procedure is discussed based on the results of non-linear static and non-linear dynamic analyses.