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

Abstract

Asymmetric structures experience uneven deformation demand among different resisting planes and storieswhen subjected to earthquake excitation. Damage is focused in some elements jeopardizing structuralintegrity. These structures are common in professional practice because of architectural and functionalityconstraints. In this scenario the use of energy dissipation devices (EDD) has arisen as an advisable solutionto balance and minimize structural damage. Procedures for the design of linear structures equipped withEDD have been widely proposed in the literature, few of them deal with the optimum spatial distributionof nonlinear systems. This paper evaluates and compares the optimized spatial damper distribution of linearand nonlinear systems. An optimization technique is presented based on control indexes called min–maxalgorithm. 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), whichis a sequential method. It is pointed out that the SSSA is a fixed step coordinate descent type method. Theexamples considered show that the SSSA is a discrete approximation of the min–max algorithm, not only forlinear but also for nonlinear structures equipped with linear and nonlinear EDD. Furthermore, it is found thatthe distribution of EDD obtained from a linear analysis is a good approximation of the nonlinear optimalsolution. The SSSA is a reliable method that can be applied to achieve drift and torsional balance fordesign purposes; moreover, it can be implemented with conventional tools available in professional practice.