Vol. 2, No. 8, 2007

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A new variable damping semiactive device for seismic response reduction of civil structures

Orlando Cundumi and Luis E Suárez

Vol. 2 (2007), No. 8, 1639–1656

A semiactive mechanism, called a VDSA (variable damping semiactive device), is proposed to reduce the seismic response of structures. It is composed of two fixed-orifice viscous fluid dampers installed in the form of a V whose top ends are attached to a floor and their lower ends to a collar that moves along a vertical rod. By varying the VDSA position one obtains an optimal instantaneous damping added to the structure. The position of the moving end is calculated with an algorithm based on a variation of the instantaneous optimal control theory which includes a generalized LQR (linear quadratic regulator) scheme. This modified algorithm, referred to as Qv, is based on the minimization of a performance index J quadratic in the state vector, the control force vector, and an absolute velocity vector. Two variants of the algorithm are used to present numerical simulations of the controlled seismic response of a single and a MDOF (multi-degree-of-freedom) structure.

semiactive systems, control algorithms, earthquake engineering, seismic response, added damping
Received: 22 May 2007
Accepted: 23 May 2007
Published: 1 October 2007
Orlando Cundumi
Department of Engineering
Caribbean University
Bayamon Campus
P.O. Box 493
Bayamon, PR 00960
United States
Luis E Suárez
Civil Engineering Department
University of Puerto Rico
P.O. Box 9041
Mayaguez, PR 00681-9041
United States