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An attempt has been made to explore the general trends in the seismic response of planasymmetric structures when subjected to near-fault and far-fault ground motions. Systems with structural wall elements in both orthogonal directions considering actual and common nonlinear behavior under bi-directional excitation were studied. Idealized single-storey models with uni-axial eccentricity were employed. The main findings are: The rotational response trend considering actual behavior method would be different from common behavior method assumption, when the system subjected to near-fault motions. In the former case, the minimum rotational response could be achieved, when stiffness and strength centers are located on opposite side of the mass center. In the latter case, stiffness eccentricity determines the minimum and maximum rotational response. General trends in the rotational demand for far-fault motions, considering two type behavior assumptions, are similar to the last case. Moreover, in near-fault motions, when stiffness and strength centers are located on opposite side of the mass center, stiff side displacement demand would be greater than that soft side which is contrary to the conventional guidelines. While, in farfault motions similar to near-fault motions which stiffness and strength centers are located on one side of the mass center, displacement demand would be according to conventional guidelines.

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An approach was formulated for the nonlinear analysis of three-dimensional dynamic soil-structure interaction (SSI) of asymmetric buildings in time domain in order to evaluate the seismic response behavior of torsionally coupled wall-type buildings. The asymmetric building was idealized as a single-storey three-dimensional system resting on different soil conditions. The soil beneath the superstructure was modeled as nonlinear solid element. As the stiffness of the reinforced concrete flexural wall is a strength dependent parameter, a method for strength distribution among the lateral force resisting elements was considered. The response of soil-structure interaction of the system under the lateral component of El Centro 1940 earthquake record was evaluated and the effect of base flexibility on the response behavior of the system was verified. The results indicated that the base flexibility decreased the torsional response of asymmetric building so that this effect for soft soil was maximum. On the other hand, the torsional effects can be minimized by using a strength distribution, when the centre of both strength CV and rigidity CR is located on the opposite side of the centre of mass CM, and SSI has no effect on this criterion.