OPTIMUM DESIGN METHODS FOR STEEL FRAMES CONSIDERING TRANSIENT DYNAMIC ELASTO-PLASTIC RESPONSES USING PARTLY AVAILABLE SENSITIVITY INFORMATION

Transactions of AIJ. Journal of structural and construction engineeringDesign problems with transient dynamic elasto-plastic analysis exhibit noisy and nonsmooth responses with respect to their design parameters. This leads to situations in which some derivatives may be inaccurate and/or computationally expensive to obtain, whereas others may be readily available. For such problems, derivative-free approaches seem to be more appropriate than conventional derivative-based methods because some derivatives do not exist and/or are noisy. High cost for derivative evaluation is also frequently encountered in real-world design problems. This paper presents a new optimization method which is essentially derivative-free. However, the proposed method can reflect the geometry of some smooth and inexpensive response functions. This enables enhancement of the derivative-free method by including the derivative information on some constraints. The approach can be interpreted as a practical compromise between derivative-based and derivative-free methods. Furthermore, the proposed method can also be interpreted as a meta-modeling framework, ensuring global convergence in nonsmooth optimization. The efficiency of the proposed method is studied through a numerical example of steel frame with transient analysis. The numerical result illustrates that the proposed method finds better solutions than typical derivative-based and derivative-free methods and shows reasonable convergence in all cases