For the design of structural systems, it is often of interest to determine the general geometric layout of the system that most efficiently supports the expected design actions. Such a design can be done by optimizing the overall layout of the structural system as well as the topology of the structure. Layout optimization is probably the most difficult class of problems in structural optimization. It is also a very important one, because it results in much higher material savings than sizing optimization of cross sections (Rozvany, 1992). In a comprehensive structural optimization process, selecting an appropriate preliminary geometric layout is of enormous importance, as it influences all the succeeding stages of the design procedure.
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