The specifications for seismic design of structures were significantly revised after the Hyogokenn-Nanbu Earthquake, and the performance-based design method is being introduced. In this seismic design, it has been mainstream to verify the seismic performance by time history response analysis. Structural optimization has been developed with the approximation concept and approximation concept also has been improved in these years. The RBF approximation method was applied to approximate the constraints of seismic design problem. In this paper, not only the seismic performance but also the repair cost is considered. Both of the constraints and objective function must be approximated. So, the convolute approximation technique is tied to apply to this seismic design problem with several numerical examples.
