Algorithm for design of controlled motion of adjacent structures

This paper presents a versatile and robust algorithm for the optimal design of adjacent structural systems linked by passive energy dissipation devices. The algorithm works both with stationary and nonstationary force input. It is a two-stage design procedure that (i) determines an active control law, and then (ii) adds damper and stiffness coefficients that are computed based on the minimization of the difference between the response of the actively controlled system and an equivalent passive control system. The algorithm is an iterative procedure that leads to a close form global optimal solution for the damping and stiffness coefficients in such a way to obtain a response as close as possible to the active control. The method is tested for two adjacent ten-degree-of-freedom spring-dashpot-mass systems. Sensitivity analysis is carried out studying the effects of period variation, the number of DOFs variation and link location using a stationary band-limited white noise input as ground acceleration. Results show that the same performance can be achieved with less amount of damping when the linear damper is located at the last mass of the system. When dampers are located in one of the node of the mode shape, the total amount of damping is higher to achieve the same performance. Copyright r 2009 John Wiley & Sons, Ltd.