Proposal of energy-based method for the design of passive energy dissipative braces

Earthquake-prone regions of the world are usually characterized by a high number of Reinforced Concrete (RC) buildings designed before seismic building codes were enforced. As a result, the amount of existing RC buildings requiring seismic assessment and likely retrofitting is large. The use of innovative techniques for the seismic amelioration of existing RC buildings has been attracting the attention of both academic and technical communities since the second half of the previous century. Among these techniques there is the employment of passive energy dissipating devices that are mounted in series to metallic braces installed within the existing RC frames. Such energy dissipating devices can be 1) fluid-viscous, 2) viscoelastic, 3) elasto-plastic, 4) frictional or 5) based on shape-memory alloys. The large number of devices available on the market is not accompanied yet, at least within the Italian Building Code, by a mature and detailed description of the design procedure, so that the practicing engineer who would like to adopt this technique is often referred to scientific publications. With the aim to contribute to fill this gap, an energy-based methodology is proposed and applied and compared with some of the most innovative design procedures available in the scientific literature to date. The validity of each procedure is appraised on the basis of non-linear static and non-linear dynamic analysis results.