The Application Of Multi-objective Fuzzy Optimization In Bridge Design

A complex system is often consist of diversity,multidimensionality,multiple criteria and uncertainty in the real world.Multi-objective fuzzy optimization is a very effective mathematical tool to tackle these kinds of problems.Under the background of bridge design,we studied a multi-objective fuzzy optimization model which use the minimum of project cost and the maximum of total cross-section rigidity(the maximum of section modulus)as the objective function in this paper.In addition,we give two practical instances and solve their models by genetic algorithm.The results obtained show a better advantage than the traditional design method.Starting with the research background and significance of multi-objective fuzzy optimization,this paper first introduces the basic concept and characteristics of the fuzzy optimization,then summarize the overseas and domestic research status and the theory of multi-objective fuzzy optimization which is usually applied in bridge design optimization.Next,we construct the steps of solving the multi-objective fuzzy optimization in bridge design.For an instance of the uniform ordinary reinforced concrete simply supported T beam and the steel box girder in bridge design,we analyzes three key elements which consist of the design variable,the objective function and the constraint conditions,and then establish the multi-objective fuzzy optimization model of the uniform ordinary reinforced concrete simply supported T beam and small steel box girder.Finally for the instance of uniform the ordinary reinforced concrete simply supported T beam and the steel box girder,we solve the optimal level cut set by using two-level comprehensive fuzzy evaluation method,and construct the fuzzy goal set,membership function.Moreover,we solve the problem by genetic algorithm to get the global optimal solution,and compare the results of multi-objective fuzzy optimization with the results of traditional experience.