Seismic protection of frame structures via semi-active control: modeling and implementation issues

Vincenzo Gattulli, Marco Lepidi and Francesco Potenza

Dipartimento di Ingegneria delle Strutture, delle Acque e del Terreno, Universitš€ dell¡¯Aquila, Italy

Abstract: Theoretical and practical issues concerning the multi-faceted task of mitigating the latero-torsional seismic
response of a prototypal frame structure with asymmetric mass distribution are approached. Chevron braces with embedded
magnetorheological dampers acting on the interstory drift are used to ensure additional energy dissipation. The semi-active
control strategy employed to govern the modification of the damper characteristics via feedback is based on the selection of
optimal forces according to a H2/LQG criterion, with respect to which the actual forces are regulated by a clipped-optimal
logic. A dynamic observer is used to estimate the state through a non-collocated placement of the acceleration sensors. Several
aspects to be addressed throughout the complex process including the design, modelization, and implementation phases of
semi-active protection systems are discussed. Finally, experimental results obtained to mitigate the motion induced by ground
excitation in a large-scale laboratory prototype, simulating the seismic response of a two-story building, are summarized.

Keywords: seismic protection; frame structures; semi-active control; magnetorheological damper


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