Seismic response of yielding structures equipped with inerters

Abstract

This paper investigates the seismic response of one- and two-degree-of-freedom yielding structures equipped with inerters at the first story. Inerters are mechanical devices that their resisting force is proportional to the relative acceleration at their end-nodes. This class of response modification devices complements the traditional supplemental damping devices that their resisting force is proportional to the relative velocity at their end-nodes, also examined in this study for comparison. The paper develops a stable nonlinear response analysis methodology that implements a state-space formulation. Given that the engagement with an inerter lengthens the apparent preyielding period of the inelastic structure, the paper shows that when a yielding structure is equipped with supplemental rotational inertia, the equal-displacement rule is valid starting from lower values of the preyielding period. The effectiveness of a single inerter versus the use of a pair of clutching inerters that can only resist the motion of the yielding structure is examined, and the paper concludes that a single inerter suppresses effectively the displacement response of inelastic structures by outperforming the response modification with supplemental damping in particular when the supporting frame of the response modification devices is compliant.