A Study on the Optimization for the Arrangement of Two Types of Supporting Columns for VLFS Using GA

Abstract

In the recent years, there are many researches about hydroelastic responses of Very Large Floating Structure (VLFS). As a result, we are now in a position to say that VLFSs can be used as airport, city base, energy facilities and so on. There are several supporting structures of VLFS. In this paper, we shall focus only on the column type and the pontoon type. These two types of supporting structures have different hydroelastic behavior. For example, wave-induced elastic responses of column type are usually smaller than the response of the pontoon type. On the other hand, large amplitude responses at both ends of the column type VLFS are expected in certain frequencies. Then we thought that combining the two types of supporting structures could increase or decrease the VLFS hydroelastic response. Because there is uncountable number of combinations, we could not evaluate the hydroelastic responses of all combinations. In order to achieve the optimum combination in realistic calculation load, the Genetic Algorithm (GA) is applied. In this research, we discuss the combination of the two types of supporting structures in order to achieve smaller hydroelastic response of the VLFS in regular and irregular waves. GA is implemented as a computer simulation in which a population of abstract representations for the supporting structures are generated (in this case, the representations are the combination of pontoons and columns), then these abstract representations are recombined creating a new generation. At each generation, the best individual (the VLFS with the minimum hydroelastic response) is chosen. After run several generations, the optimum solution is reached.