AN INNOVATIVE CONNECTION FOR SEISMIC DESIGN OF STEEL EXOSKELETONS

Since the 1980s, the use of steel exoskeletons for seismic retrofit of existing buildings has become widely popular. They are designed to increase global lateral stiffness and to bear the horizontal seismic action in an existing structure, also frequently equipped with energy dissipation systems permitting to reduce the seismic design actions. To date many studies have been conducted on steel exoskeletons, both in terms of design methodologies and construction details. Among these, a central role is played by the steel connection, that can be either elastic or dissipative, because in this element seismic forces transmitted by the existing structure to the exoskeleton system are concentrate. In this work an innovative steel connection for exoskeleton is examined, having also a modest dissipative capacity. At first, the connection is characterized through detailed finite elements analyses, performed by varying some of its fundamental characteristics. Then, numerical investigations are conducted on a case study, represented by an existing reinforced concrete structure connected to the exoskeleton through the innovative connection. Investigations are conducted with the aim of evaluating the influence of the connection considered on the combined system global response, represented by the existing structure plus the exoskeleton.