Optimal control of linear and nonlinear asymmetric structures by means of passive energy dampers

Asymmetric structures experience uneven deformation demand among different resisting planes and stories when subjected to earthquake excitation. Damage is focused in some elements jeopardizing structural integrity. These structures are common in professional practice because of architectural and functionality constraints. In this scenario the use of energy dissipation devices (EDD) has arisen as an advisable solution to balance and minimize structural damage. Procedures for the design of linear structures equipped with EDD have been widely proposed in the literature, few of them deal with the optimum spatial distribution of nonlinear systems. This paper evaluates and compares the optimized spatial damper distribution of linear and nonlinear systems. An optimization technique is presented based on control indexes called minmax algorithm. Then, this technique is compared with two simple methodologies: (i) the fully stressed design, which is an analysis-redesign procedure, and (ii) the simplified sequential search algorithm (SSSA), which is a sequential method. It is pointed out that the SSSA is a fixed step coordinate descent type method. The examples considered show that the SSSA is a discrete approximation of the minmax algorithm, not only for linear but also for nonlinear structures equipped with linear and nonlinear EDD. Furthermore, it is found that the distribution of EDD obtained from a linear analysis is a good approximation of the nonlinear optimal solution. The SSSA is a reliable method that can be applied to achieve drift and torsional balance for design purposes; moreover, it can be implemented with conventional tools available in professional practice. Copyright (c) 2012 John Wiley & Sons, Ltd.