Genetic algorithm in locating the optimum mid-connection of Off-Centre braced system

Abstract

In this article, a particular Off-Centre braced system is examined. This bracing system consists of three members, where the diagonal member is not straight and it is connected to the corner of the frame by a third member. The out-of-straightness of the diagonal member introduces eccentricity to the system. This system improves the energy dissipation due to earthquake as well as its eccentricity allows architects to have more openings in the panel areas. In this regard, the location of brace elements connection point has significant effect on the stiffness of the system. In order to assess the influence of the connection position and other parameters such as cross section of brace elements and span/height ratio of the braced frame on the stiffness of the system, analytical equations have been developed. A new method based on Genetic algorithm (GA) to obtain the connection point is also proposed. The importance of elite individuals together with selection, mutation and crossover operator between populations are also examined. In order to achieve the best and practical location of the connection point, two equations for boundary conditions with regards to the opening dimensions are set in a computer model developed in MATLAB program. The results indicate that the stiffness decreases as the connection point moves closer to the corner of the frame. Additionally, the proposed method is proven to be efficient in determining the connection point due to its accuracy and minimal computational time required compare to conventional trial and error method.