A new swift algorithm for bi-objective optimum design of steel moment frames

Abstract

In this paper, a new algorithm is proposed to multi-objective optimum seismic design of steel moment frames. This algorithm is based on the uniform damage (also known as uniform deformation) theory and so-called multi-objective uniform damage optimization (MUDO). MUDO is a swift algorithm formulated according to a bi-objective approach. Structural weight and maximum interstory drift ratio (IDR) are treated as two conflicting objectives representing economy and safety measures, respectively, and they are minimized simultaneously subject to a set of design constraints. To achieve the optimal Pareto front, MUDO tries to create a uniform distribution of story drifts in the structure and bring it to a target value that gradually varies from the low (minimum damage) to high (maximum damage). In this way, the algorithm obtains a set of optimal solutions in terms of structural weight at different damage levels, which is the Pareto front. To demonstrate the efficiency and robustness of the proposed algorithm, its results for 3-, 6- and 9-story steel moment frames are compared with those of two well-known multi-objective optimization algorithms, NSGA-II and MOPSO. Results indicate that MUDO can achieve better optimal solutions set in a much less computational time than the other two methods.