COMPUTATIONAL MORPHOGENESIS OF DISCRETE STRUCTURES BASED ON FUZZY THEORY

摘要

Present paper proposes a structural optimization method for truss and frame structures having some uncertain factors in its constitutive materials, configurations or design loads by using fuzzy theory as well as genetic algorithm techniques. Genetic algorithm has been already recognized as a strong and a useful tool for optimization problems including discrete variables and has been applied for topology optimization problems of trusses and frames. On the other hand, uncertainties existing in structural problems such as those of the design loads, the structural configurations and the constitutive materials should be dealt with especially from the viewpoint of the practical structural design. Probability statistics theory has been considered as the only technique for reliability analysis that can treat the uncertainties inevitably existing in structures. Probability theory can be used only when sufficient numbers of random data exist in the problem to define the probability density function. However, in actual structural design, such cases can be said to occur very rarely. Furthermore, although various factors such as human error, etc. must also be taken into consideration in order to consider the safety of real structures, they cannot be defined within a framework of the traditional probability theory. In this paper, inclusion of such factors are reasonably realized through the usage of the fuzzy theory and the topology optimization problem of frame structures having uncertainties in their materials or configurations is shown to be rationally solved