V. Plevris, Postgraduate Thesis "Multi-objective Optimum Design of Structures with use of Evolution Strategies", Institute of Structural Analysis and Seismic Research, School of Civil Engineering, National Technical University of Athens (NTUA), 2001.

Abstract
The Postgraduate Thesis deals with the problem of Multi-Objective optimum design of structures with use of Evolution Strategies (ES). It consists of 6 chapters, the first five dealing with the theoretical background; Optimum design of structures in general, Multi-Objective optimization, the Evolution Strategies method, dynamics of structures and the Direct Time Integration method. The sixth chapter deals with the practical part, the application of the methods and the corresponding results.
The structure that is examined is a six-storey steel space frame. The applied optimization method is a multi-membered ES scheme (M-ES). The objective in every case is finding the Pareto optimal solution of the multi-objective optimization problem, which in the special case of two objective functions can be represented in a diagram as a curve. The design variables of the optimization problem concern the geometry of the cross sections of the columns and beams and specifically the height and width of the W-shape cross sections. The two objective functions are the weight and the maximum horizontal displacement of the structure. The constraints concern the allowable stresses of the members and the maximum allowable inter-storey drift. The applied ES scheme is a scheme of 5 parents and 5 offsprings (5+5 ES). The dynamic analyses are performed with the Direct Time Integration method, using three artificial accelerogramms compatible with the response spectrum of the Greek seismic code EAK 2000. The loads applied are both static and static + dynamic. The examined Multi-Objective Optimization methods are the Linear Weighting Method, the Constraints Method and the Distance Method.