Optimal distribution of viscous dampers(VDs) in direct displacement-based design (DDBD) of controlled structures

Abstract

In this paper to increase the efficiency of direct displacement based design (DDBD) in designing structures equipped with viscous dampers (VDs), a method has been proposed to determine optimal distribution of VDs. The proposed method has been based on defining an optimization problem which minimizes the sum of damper coefficients to achieve the required equivalent viscous damper. To solve the optimization problem the distributed genetic algorithm (DGA) has been applied. To illustrate the method, three 2, 5 and 20 story steel frames equipped with linear VDs and designed using DDBD, have been considered and optimal placement of VDs has been determined. The controlled structures using uniform distribution (UD) and optimal distribution (OD) of VDs subjected to ten artificial earthquakes compatible with design spectrum and nonlinear time history analysis has been conducted. Results show that to achieve the same equivalent viscous damping for both uniform and optimal distributed VDs distribution, using OD has reduced significantly the sum of dampers coefficient (up to 30%) as well as the maximum damping force(up to 24%). Also evaluating the performance of controlled structures under different artificial records has shown that using OD has led to less control system cost while both distributions has similar performance.

Keywords

• performance-based design
• direct displacement-based design
• fluid viscous damper
• optimization
• distributed genetic algorithm