移動漸近線法的原理是將一個函數利用倒數近似法加上中介變數轉換為近似原問題的函數。因移動漸近線法可以處理各種設計參數並因應各式目標函數與限制條件，本研究應用移動漸近線法之特性得到函數之近似式並利用對偶法對最佳化問題求解。對偶法為將原本的最小化問題以與之有關的最大化對偶函數取代。也就是將原設計問題轉換為凸性且為可分離的子問題，這有助於結構最佳化問題能夠快速地求解。因此本研究應用移動漸近線法得到結構行為之近似函數，再採用對偶法執行結構之最佳化設計。 Method of Moving Asymptotes (MMA) is used by reciprocal approximate and moving asymptotes to approximate an original function. Because MMA can deal with various kinds of design parameters and handle all kinds of objective and constraint functions, this study applies the characteristics of MMA to obtain the approximation function and then uses dual method to solve the problem. Dual method is that the original minimization problem is replaced by the maximization of dual function relating to it. That is, the dual method was used to solve design problem by a subproblem, which is convex and separable. Therefore, this study applies MMA to obtain the approximate function of structural behavior, and then adopts dual method to obtain the optimum design of structures.