The near field method: a modified equivalent linear method for dynamic soil structure interaction analysis. Part II: verification and example application
Usually for modeling of soil in a direct soil structure interaction (SSI) problem, the equivalent linear soil properties are used. However, this approach is not valid in the vicinity of a foundation, where the soil experiences large strains and a high level of nonlinearity because of structural vibrations. The near field method was developed and described in a companion paper to overcome this limitation. This method considers the effects of large strains and suggests a shear modulus and a damping ratio further modified in the near field of a foundation. Validity and performance of this approach are evaluated, application examples are explained and the results of a parametric study about the role of soil and structure parameters in the extent of SSI effects on the nonlinear seismic response of structures are presented in this paper. One real existing and five, ten, fifteen and twenty story moment resisting frame steel buildings with two different site conditions corresponding to firm and soft soils are considered and the responses obtained from the near field method are compared with the recorded and rigorous responses. Moreover, various SSI modeling techniques are employed to investigate the accuracy and performance of each approach. The results show that the near field method is a simple yet accurate enough approach for analysis of direct SSI problems.
Bulletin of Earthquake Engineering