The seismic design requirements in Building Standard Law of Japan revised in June 2000 toward a performance-based design framework,a new seismic design method called "Response and Limit Strength Calculation (RLSC)" has developed.The features of RLSC are summarized as follows;(1)The regulation of the design earthquake motion as an acceleration response spectrum at outcropped engineering bedrock, (2)Incorporation of nonlinear amplification effect of surface strata, (3)Incorporation of the effects of soil-structure interaction(SSI), and (4)Modeling of multi-stories building into an equivalent single-degree-of-freedom system.Focusing on above items (2)and (3),this paper describes to some tries of incorporation of SSI using response spectrum method in structural design practice.