Wind-Resistant Optimization Design Of Guyed Mast Structure By Genetic Algorithm

With the increasing development in communication industry in our country, the guyed masts are constructed more and more widely. As its characteristics in high flexibility, light weight and small damping, the guyed masts are more sensitive to lateral load such as wind loading. The cables and structural elements with large slendness ratio induced the geometric nonlinear effect in the guyed mast. Therefore it is necessary to consider the geometric nonlinear effect in the wind-induced response analysis for this kind of structure. Meanwhile with the development in computer science and structural optimization theory, the intelligent optimization algorithms has been widely used in the optimization design of engineering structures in recent years.A 288m-height guyed mast structure with four levels in cable arrangement is selected as a research example in this study. The wind-resistance optimization design procedure based on the genetic algorithm is proposed in this study for the guyed mast under the equivalent static wind load.1. The wind loading characteristics and along-wind induced response of the guyed masts are introduced briefly in Chapter 1. The developing history of structural optimization method on space truss are described in detail. Finally the main features of intelligent optimization algorithm such as genetic algorithm is introduced.2. Under the MATLAB environment of SAP2000 API, the finite element model of guyed mast is constructed by parametric modeling method. The geometry nonlinear effect on the dynamic characteristics of the guyed masts is considered. Modal analysis was conducted for the guyed mast to obtain its natural frequencies and mode shapes. By random vibration theory, the along-wind response and the corresponding equivalent static wind load for the guyed mast was obtained for the following optimization procedure.3. In Chapter 3, the basic operations and implementation procedure for Simple Genetic Algorithm(SGA) have been analyzed in detail. The disadvantage of SGA algorithm was described in this section. An Improved Adaptive Genetic Algorithm(IAGA) is proposed by adjusting the crossover and mutation probability with the variation of fitness value. In the evolution process, the static penalty function is also introduced in the IAGA for dealing with the constraint condition.4. Wind-resistant optimization design of the guyed mast is conducted by the IAGA method in Chapter 5. The total weight of the structure is selected as the objective function. The size of the structural elements, the pretension force in cables and the anchor location of cables at the ground are selected as optimized design variables. The element stress and the wind-induced displacement atop of the guyed mast are adopted as the constraint conditions for the structural optimization design. By introducing the static penalty and fitness function, the modified objective function are established. Through seeking the maximum value of the fitness function, the minimum value in the total weight of the guyed masts would be obtained through the wind-resistant optimization design procedure. In the end, the optimization results by GA are analyzed and discussed.