With the advancement of technology and construction techniques, newly built structures fully comply with regulatory requirements, including seismic safety standards. However, many existing buildings were designed without seismic criteria, making them particularly vulnerable to earthquake effects. In response to the need to safeguard and protect existing structures, many technologies are being developed. However, these strategies are often invasive, not maintaining the original configuration of the structure. In this context, the need for more sophisticated technologies such as the ones involving the use of mechanical metamaterials (i.e., engineered materials with mechanical properties not existing in nature), arises. This thesis investigates a seismic improvement solution, whose dissipative capabilities are primarily based on the properties of metamaterials, which allow for optimizing the response of structures subjected to seismic excitations.