Seismic response of structure under soil-structure interaction effect (SSI) is an impressive topic in earthquake engineering domain. Many analytical models and methods have been utilized for research and practical work. These methods can be categorized as direct and substructure (indirect) approach. Due to the simplicity requirement, substructure approach is often used in practical work and research field. In this approach, the procedure is distinguished into three steps: foundation input motion, dynamic impedances, and dynamic response of structure. However, the state of problem in dynamic impedance step is found and need more improvement.

The objective of this paper is to propose a new analytical model base on substructure approach considering nonlinear response of soil properties, in each time step, in dynamic impedance determination step. This proposed model brings the whole analysis of structure into the fully nonlinear response which can represent the actual response of structure, under SSI effect, subjected to earthquake loading.

In order to obtain the objective of this paper, the nonlinear response of RC frame structure is performed. This structure was assumed to rest on rigid surface foundation and soil deposit in depth 17m subjected to vertically incident S wave. The comparison between current and new analytical model of substructure approach is performed to clarify the nonlinear response of structure under both models.